Magnet protection studies and heater design

Susana Izquierdo Bermudez

2Susana Izquierdo Bermudez

OUTLINE1 Margin and MIITs overview2 Quench study based on FNAL 11T tests results

1 Longitudinal quench propagation2 Heaters delay3 Quench Integral (QI)4 Time budget

3 Minimize heaters delay1 Inter-layer heaters2 Reduce kapton thickness from heater to coil3 Quench heater design optimization

4 Quench performance under accelerator conditions5 Additional remarks6 Baseline design7 ConclusionsFuture actions

3Susana Izquierdo Bermudez

1 Margin and MIITs overview

11 T 1122 T central field

145 K

5 K

Temperature Margin T(MIITs) 11T cable

Parameter MB 11TMIITs to reach 400 K 8T MA2s 52 18

Temperature margin LF 4 8-9

Temperature margin HF 3-4 5-9

Differential Inductance mHm 69 117

Stored energy kJm 567 897

4Susana Izquierdo Bermudez

Longitudinal quench propagation2D+1 thermal network Study the propagation of an initial resistive zone of 3 cm length in different turnsI = 11850 A Tbath=19KElement size in the longitudinal direction = 1 mmAdaptive time stepping (min = 10-7s max = 10-5s]

2 3 4 5 6 7 8 9 10 11 120

5

10

15

20

25

30

35ROXIE

Experimental

Average field in the conductor (T)lo

ngitu

dina

l pro

paga

tion

ve-

loci

ty (m

s)

Pole turn IL (high field) v asymp 30 msMid-plane turn OL (low field) v asymp 65 ms

The longitudinal quench propagation velocity in MBHSP01 was measured in one of the quenches in the inner-layer pole turn at 45 K using the time-of-flight method as ~27 ms at 73 of SSL at 45 K

2Quench study based on FNAL 11T tests longitudinal quench propagation

Block 572 ms

Block 6134 ms

Experimental data courtesy of Guram Chlachidze

5Susana Izquierdo Bermudez

Insulation heater2coil = 114 microm kapton + 125 microm G10Insulation heater2bath = 508 microm kapton

2Quench study based on FNAL 11T tests Quench Heaters Delay

40 45 50 55 60 65 70 75 800

102030405060708090

measured MBSHP02 roxie MBSHP02measured MBSHP01 roxie MBSHP01

IIss ()

PH d

elay

(ms)

HFU voltage of 400 V ~ 65 Wcm2 peak power density

MBSHP02 Po LF = 65 Wcm2 Po HF=39 Wcm2 =31 ms

Experimental data courtesy of Guram ChlachidzeROXIE quench heater model

heater

Tuning factor (k) on GijTheater2coilbath to fit

experimental and computed heater delays

k=042

6Susana Izquierdo Bermudez

2Quench study based on FNAL 11T tests QI study

I0 = 11850 A Tbath = 19 K

MIITs after heater effective [MA2s]

MIITs from heater fired until effective [MA2s]

OL-IL delay[ms]

PH delay[ms]

Experimental data 108 37 134 asymp27CASE1 OL heaters fired t=0(computed heat transfer from heater to coil) 123 29 425 21

CASE2 OL quenched PH measured delay(OL fully quenched at PH measured delay) 114 38 338 27

Max Temperature [K]

Heaters fired t=0

OL quenched measured delay

Manual trips with the two operating protection heatersDump delay 1000 ms Self-dump Experimental data courtesy of Guram Chlachidze

7Susana Izquierdo Bermudez

Manual trips with the two operating protection heatersDump delay 1000 ms Self-dump

2Quench study based on FNAL 11T tests QI study

Remark MATPRO database material properties MIITs 6 lower for CUDICryocomp database (mainly due to Copper Thermal Conductivity)

httpsespacecernchroxieDocumentationMaterialspdf

084 MIITs difference

Additional time budget 6 ms

Experimental data courtesy of Guram Chlachidze

QI after heaters effective

8Susana Izquierdo Bermudez

2Quench study based on FNAL 11T tests Time budget

120591119887119906119889119892119890119905=119876119868119898119886119909minus119876119868119889119890119888119886119910

119868 02

QImax = 18 MA2s

QIdecay = 108 MA2s

I0 = 11850 A

(experimental)

120591119887119906119889119892119890119905=51119898119904

Detection timebull Time to get over the threshold 3-6 msbull Validation time 10 ms

Heating firing delay 5 ms Heater delay (experimental) 27 ms

Time needed to quench45-48 ms

Non-redundant (all quench heaters fired)

Redundant (half of the quench heaters fired)

QIdecay = 116 MA2s(experimental)

120591119887119906119889119892119890119905=46119898119904

We are tight We need to minimize heaters delayactual value in RB circuits 30 ms

9Susana Izquierdo Bermudez

3 Minimize heaters delay inter-layer heaters

Parameter Case 1

(only OL)Case 6(OL+IL)

OL HF heater delay ms 146 101OL LF heater delay ms 277 195

IL delay ms 565 70MIITs total MA2s 182 152

MIITs after heater effective MA2s 136 117MIITs heater fired until effective MA2s 21 10

Peak temperature in coil K 440 322Peak temperature in heater K 292 260

Δ OL HF QHdelay = - 31 Δ IL Qhdelay = - 88 ΔTmax = - 27

RemarksThermal contact resistances (eg between insulation layers) not included the same scaling factor as the one used to fit the FNAL test data is kept for this simulationThe insulation is a combination of glass fiber and Mica At the moment in the model we use G10

CASE 1 Only Outer Layer Heaters

Heater parameters

bull Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulation

bull Insulation heater2bath = 508 microm kaptonbull Po = 70 Wcm2 =74 ms ΔtQHdelay=5 msbull Non-redundant configuration

Some technical development required before inter-layer heaters become a feasible option

CASE 2 Outer Layer + Inter Layer Heaters

10Susana Izquierdo Bermudez

3 Minimize heaters delay reduce kapton thickness

Parameter Case 1114microm k

Case 250microm k

OL HF heater delay ms 21 14OL LF heater delay ms 335 24

IL delay ms 71 63MIITs total MA2s 176 163

MIITs after heater effective MA2s 122 12MIITs heater fired until effective MA2s 46 4

Peak temperature in coil K 422 367Peak temperature in heater K 208 196

Δ OL HF QHdelay = - 33 ΔTmax = - 13

CASE 1Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kaptonCASE 2Insulation heater2coil = 50 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kapton

Po = 64 Wcm2 (LF) 39 Wcm2 (HF) =31 ms ΔtQHdelay =5ms Non-redundant configurationQuench validation 100mV 10ms

11Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

DESIGN GUIDELINESbull Heaters should cover as many turns as possiblebull Design should be suitable for a 55 m length magnet heating stationsbull Aiming to heater delays lt 20 ms bull Two independent circuits (for redundancy)bull Higher power density in the LF region

Circuit 1Circuit 2

12Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

For long magnets the total heater resistance becomes too high Heating stations2 possible options

Heating stations LARPLQ example wide section = 23 mm narrow section 9 mm

distance between stations 100mm

LHC copper plated solutionMB example 15 mm width 400 mm plated 120 mm un-plated

Qualitative tests at CERN to understand how smooth the transition between narrow and wide section should be in order to avoid high spot temperaturesMore development required to find a solution which combines smooth transition enough coverage and distance in between heater stations small enough to allow fast quench propagation in the longitudinal direction

BASELINE SOLUTION FOR THE FIRST MODEL = COPPER PLATED SOLUTION Thanks to Vladimir Datskov amp Glyn Kirby

13Susana Izquierdo Bermudez

50 60 70 80 90 100 110 120 130 140 15000

200

400

600

800

1000

1200

1400

Low Field Region High Field Region

Heater Current (A)

Pow

er d

ensi

ty (W

cm

2)

Operation area

3 Minimize heaters delay heater design optimization

bull Width -gt Cover as many turns as possible

bull LF 20 mm bull HF 24 mm

bull Power densitybull LF asymp 75 Wcm2

bull HFasymp 55 Wcm2

Even if the operational current is expected to be in the range 100-120 A it would be good to have the possibility to go up to 150 A during short model tests to check the saturation of the system in terms of heater delays

119875119889=1198682119877119908119871

119877=120588 119871119908119905

119875119889=1198682 1205881199082119905

Heater width20 mm LF 24 mm HFρss=7810-7Ωm RRR=134

bull Distance between heater stations -gt quench propagation in between stations asymp 5 msbull LF 90 mmbull HF 130 mm

bull Coverage maximum coverage keeping the resistance within the allowable limits for a 55m magnet (depends on the number of power suppliesheater circuits)

Coverage Distance between stations

wid

th

14Susana Izquierdo Bermudez

OBJECTIVE Stay within LHC standard quench heater supply limits(V = 450 V C=705 mF Ip asymp 85 A but it can safely operate up to 300 A)

V (V)

I (A)

C (mF)

Tau(ms)

Max Energy (kJ)

Power density(Wcm2)

900 120705 55

28 84 (LF)58 (HF)

850 113 25 75 (LF)52 (HF)

For a 55 m magnet and 50 mm coverage

During first short model test Higher currents (up to 150) to check the saturation of the system in terms of heater delay

3 Minimize heaters delay heater design optimization

15Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

Baseline solution

+-+-

-

+

-

+--+

+

50 90130

202

4

Heater strip Heater circuit

If heater delays becomes too high andor current decay too slowhellipwe still canDuplicate the heater coverage (50mm100mm) + parallel circuit

Duplicate the heater coverage (50mm100mm) + independent circuits

We need 2 times more current from the power supply

We duplicate the number of power supplies

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

2Susana Izquierdo Bermudez

OUTLINE1 Margin and MIITs overview2 Quench study based on FNAL 11T tests results

1 Longitudinal quench propagation2 Heaters delay3 Quench Integral (QI)4 Time budget

3 Minimize heaters delay1 Inter-layer heaters2 Reduce kapton thickness from heater to coil3 Quench heater design optimization

4 Quench performance under accelerator conditions5 Additional remarks6 Baseline design7 ConclusionsFuture actions

3Susana Izquierdo Bermudez

1 Margin and MIITs overview

11 T 1122 T central field

145 K

5 K

Temperature Margin T(MIITs) 11T cable

Parameter MB 11TMIITs to reach 400 K 8T MA2s 52 18

Temperature margin LF 4 8-9

Temperature margin HF 3-4 5-9

Differential Inductance mHm 69 117

Stored energy kJm 567 897

4Susana Izquierdo Bermudez

Longitudinal quench propagation2D+1 thermal network Study the propagation of an initial resistive zone of 3 cm length in different turnsI = 11850 A Tbath=19KElement size in the longitudinal direction = 1 mmAdaptive time stepping (min = 10-7s max = 10-5s]

2 3 4 5 6 7 8 9 10 11 120

5

10

15

20

25

30

35ROXIE

Experimental

Average field in the conductor (T)lo

ngitu

dina

l pro

paga

tion

ve-

loci

ty (m

s)

Pole turn IL (high field) v asymp 30 msMid-plane turn OL (low field) v asymp 65 ms

The longitudinal quench propagation velocity in MBHSP01 was measured in one of the quenches in the inner-layer pole turn at 45 K using the time-of-flight method as ~27 ms at 73 of SSL at 45 K

2Quench study based on FNAL 11T tests longitudinal quench propagation

Block 572 ms

Block 6134 ms

Experimental data courtesy of Guram Chlachidze

5Susana Izquierdo Bermudez

Insulation heater2coil = 114 microm kapton + 125 microm G10Insulation heater2bath = 508 microm kapton

2Quench study based on FNAL 11T tests Quench Heaters Delay

40 45 50 55 60 65 70 75 800

102030405060708090

measured MBSHP02 roxie MBSHP02measured MBSHP01 roxie MBSHP01

IIss ()

PH d

elay

(ms)

HFU voltage of 400 V ~ 65 Wcm2 peak power density

MBSHP02 Po LF = 65 Wcm2 Po HF=39 Wcm2 =31 ms

Experimental data courtesy of Guram ChlachidzeROXIE quench heater model

heater

Tuning factor (k) on GijTheater2coilbath to fit

experimental and computed heater delays

k=042

6Susana Izquierdo Bermudez

2Quench study based on FNAL 11T tests QI study

I0 = 11850 A Tbath = 19 K

MIITs after heater effective [MA2s]

MIITs from heater fired until effective [MA2s]

OL-IL delay[ms]

PH delay[ms]

Experimental data 108 37 134 asymp27CASE1 OL heaters fired t=0(computed heat transfer from heater to coil) 123 29 425 21

CASE2 OL quenched PH measured delay(OL fully quenched at PH measured delay) 114 38 338 27

Max Temperature [K]

Heaters fired t=0

OL quenched measured delay

Manual trips with the two operating protection heatersDump delay 1000 ms Self-dump Experimental data courtesy of Guram Chlachidze

7Susana Izquierdo Bermudez

Manual trips with the two operating protection heatersDump delay 1000 ms Self-dump

2Quench study based on FNAL 11T tests QI study

Remark MATPRO database material properties MIITs 6 lower for CUDICryocomp database (mainly due to Copper Thermal Conductivity)

httpsespacecernchroxieDocumentationMaterialspdf

084 MIITs difference

Additional time budget 6 ms

Experimental data courtesy of Guram Chlachidze

QI after heaters effective

8Susana Izquierdo Bermudez

2Quench study based on FNAL 11T tests Time budget

120591119887119906119889119892119890119905=119876119868119898119886119909minus119876119868119889119890119888119886119910

119868 02

QImax = 18 MA2s

QIdecay = 108 MA2s

I0 = 11850 A

(experimental)

120591119887119906119889119892119890119905=51119898119904

Detection timebull Time to get over the threshold 3-6 msbull Validation time 10 ms

Heating firing delay 5 ms Heater delay (experimental) 27 ms

Time needed to quench45-48 ms

Non-redundant (all quench heaters fired)

Redundant (half of the quench heaters fired)

QIdecay = 116 MA2s(experimental)

120591119887119906119889119892119890119905=46119898119904

We are tight We need to minimize heaters delayactual value in RB circuits 30 ms

9Susana Izquierdo Bermudez

3 Minimize heaters delay inter-layer heaters

Parameter Case 1

(only OL)Case 6(OL+IL)

OL HF heater delay ms 146 101OL LF heater delay ms 277 195

IL delay ms 565 70MIITs total MA2s 182 152

MIITs after heater effective MA2s 136 117MIITs heater fired until effective MA2s 21 10

Peak temperature in coil K 440 322Peak temperature in heater K 292 260

Δ OL HF QHdelay = - 31 Δ IL Qhdelay = - 88 ΔTmax = - 27

RemarksThermal contact resistances (eg between insulation layers) not included the same scaling factor as the one used to fit the FNAL test data is kept for this simulationThe insulation is a combination of glass fiber and Mica At the moment in the model we use G10

CASE 1 Only Outer Layer Heaters

Heater parameters

bull Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulation

bull Insulation heater2bath = 508 microm kaptonbull Po = 70 Wcm2 =74 ms ΔtQHdelay=5 msbull Non-redundant configuration

Some technical development required before inter-layer heaters become a feasible option

CASE 2 Outer Layer + Inter Layer Heaters

10Susana Izquierdo Bermudez

3 Minimize heaters delay reduce kapton thickness

Parameter Case 1114microm k

Case 250microm k

OL HF heater delay ms 21 14OL LF heater delay ms 335 24

IL delay ms 71 63MIITs total MA2s 176 163

MIITs after heater effective MA2s 122 12MIITs heater fired until effective MA2s 46 4

Peak temperature in coil K 422 367Peak temperature in heater K 208 196

Δ OL HF QHdelay = - 33 ΔTmax = - 13

CASE 1Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kaptonCASE 2Insulation heater2coil = 50 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kapton

Po = 64 Wcm2 (LF) 39 Wcm2 (HF) =31 ms ΔtQHdelay =5ms Non-redundant configurationQuench validation 100mV 10ms

11Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

DESIGN GUIDELINESbull Heaters should cover as many turns as possiblebull Design should be suitable for a 55 m length magnet heating stationsbull Aiming to heater delays lt 20 ms bull Two independent circuits (for redundancy)bull Higher power density in the LF region

Circuit 1Circuit 2

12Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

For long magnets the total heater resistance becomes too high Heating stations2 possible options

Heating stations LARPLQ example wide section = 23 mm narrow section 9 mm

distance between stations 100mm

LHC copper plated solutionMB example 15 mm width 400 mm plated 120 mm un-plated

Qualitative tests at CERN to understand how smooth the transition between narrow and wide section should be in order to avoid high spot temperaturesMore development required to find a solution which combines smooth transition enough coverage and distance in between heater stations small enough to allow fast quench propagation in the longitudinal direction

BASELINE SOLUTION FOR THE FIRST MODEL = COPPER PLATED SOLUTION Thanks to Vladimir Datskov amp Glyn Kirby

13Susana Izquierdo Bermudez

50 60 70 80 90 100 110 120 130 140 15000

200

400

600

800

1000

1200

1400

Low Field Region High Field Region

Heater Current (A)

Pow

er d

ensi

ty (W

cm

2)

Operation area

3 Minimize heaters delay heater design optimization

bull Width -gt Cover as many turns as possible

bull LF 20 mm bull HF 24 mm

bull Power densitybull LF asymp 75 Wcm2

bull HFasymp 55 Wcm2

Even if the operational current is expected to be in the range 100-120 A it would be good to have the possibility to go up to 150 A during short model tests to check the saturation of the system in terms of heater delays

119875119889=1198682119877119908119871

119877=120588 119871119908119905

119875119889=1198682 1205881199082119905

Heater width20 mm LF 24 mm HFρss=7810-7Ωm RRR=134

bull Distance between heater stations -gt quench propagation in between stations asymp 5 msbull LF 90 mmbull HF 130 mm

bull Coverage maximum coverage keeping the resistance within the allowable limits for a 55m magnet (depends on the number of power suppliesheater circuits)

Coverage Distance between stations

wid

th

14Susana Izquierdo Bermudez

OBJECTIVE Stay within LHC standard quench heater supply limits(V = 450 V C=705 mF Ip asymp 85 A but it can safely operate up to 300 A)

V (V)

I (A)

C (mF)

Tau(ms)

Max Energy (kJ)

Power density(Wcm2)

900 120705 55

28 84 (LF)58 (HF)

850 113 25 75 (LF)52 (HF)

For a 55 m magnet and 50 mm coverage

During first short model test Higher currents (up to 150) to check the saturation of the system in terms of heater delay

3 Minimize heaters delay heater design optimization

15Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

Baseline solution

+-+-

-

+

-

+--+

+

50 90130

202

4

Heater strip Heater circuit

If heater delays becomes too high andor current decay too slowhellipwe still canDuplicate the heater coverage (50mm100mm) + parallel circuit

Duplicate the heater coverage (50mm100mm) + independent circuits

We need 2 times more current from the power supply

We duplicate the number of power supplies

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

3Susana Izquierdo Bermudez

1 Margin and MIITs overview

11 T 1122 T central field

145 K

5 K

Temperature Margin T(MIITs) 11T cable

Parameter MB 11TMIITs to reach 400 K 8T MA2s 52 18

Temperature margin LF 4 8-9

Temperature margin HF 3-4 5-9

Differential Inductance mHm 69 117

Stored energy kJm 567 897

4Susana Izquierdo Bermudez

Longitudinal quench propagation2D+1 thermal network Study the propagation of an initial resistive zone of 3 cm length in different turnsI = 11850 A Tbath=19KElement size in the longitudinal direction = 1 mmAdaptive time stepping (min = 10-7s max = 10-5s]

2 3 4 5 6 7 8 9 10 11 120

5

10

15

20

25

30

35ROXIE

Experimental

Average field in the conductor (T)lo

ngitu

dina

l pro

paga

tion

ve-

loci

ty (m

s)

Pole turn IL (high field) v asymp 30 msMid-plane turn OL (low field) v asymp 65 ms

The longitudinal quench propagation velocity in MBHSP01 was measured in one of the quenches in the inner-layer pole turn at 45 K using the time-of-flight method as ~27 ms at 73 of SSL at 45 K

2Quench study based on FNAL 11T tests longitudinal quench propagation

Block 572 ms

Block 6134 ms

Experimental data courtesy of Guram Chlachidze

5Susana Izquierdo Bermudez

Insulation heater2coil = 114 microm kapton + 125 microm G10Insulation heater2bath = 508 microm kapton

2Quench study based on FNAL 11T tests Quench Heaters Delay

40 45 50 55 60 65 70 75 800

102030405060708090

measured MBSHP02 roxie MBSHP02measured MBSHP01 roxie MBSHP01

IIss ()

PH d

elay

(ms)

HFU voltage of 400 V ~ 65 Wcm2 peak power density

MBSHP02 Po LF = 65 Wcm2 Po HF=39 Wcm2 =31 ms

Experimental data courtesy of Guram ChlachidzeROXIE quench heater model

heater

Tuning factor (k) on GijTheater2coilbath to fit

experimental and computed heater delays

k=042

6Susana Izquierdo Bermudez

2Quench study based on FNAL 11T tests QI study

I0 = 11850 A Tbath = 19 K

MIITs after heater effective [MA2s]

MIITs from heater fired until effective [MA2s]

OL-IL delay[ms]

PH delay[ms]

Experimental data 108 37 134 asymp27CASE1 OL heaters fired t=0(computed heat transfer from heater to coil) 123 29 425 21

CASE2 OL quenched PH measured delay(OL fully quenched at PH measured delay) 114 38 338 27

Max Temperature [K]

Heaters fired t=0

OL quenched measured delay

Manual trips with the two operating protection heatersDump delay 1000 ms Self-dump Experimental data courtesy of Guram Chlachidze

7Susana Izquierdo Bermudez

Manual trips with the two operating protection heatersDump delay 1000 ms Self-dump

2Quench study based on FNAL 11T tests QI study

Remark MATPRO database material properties MIITs 6 lower for CUDICryocomp database (mainly due to Copper Thermal Conductivity)

httpsespacecernchroxieDocumentationMaterialspdf

084 MIITs difference

Additional time budget 6 ms

Experimental data courtesy of Guram Chlachidze

QI after heaters effective

8Susana Izquierdo Bermudez

2Quench study based on FNAL 11T tests Time budget

120591119887119906119889119892119890119905=119876119868119898119886119909minus119876119868119889119890119888119886119910

119868 02

QImax = 18 MA2s

QIdecay = 108 MA2s

I0 = 11850 A

(experimental)

120591119887119906119889119892119890119905=51119898119904

Detection timebull Time to get over the threshold 3-6 msbull Validation time 10 ms

Heating firing delay 5 ms Heater delay (experimental) 27 ms

Time needed to quench45-48 ms

Non-redundant (all quench heaters fired)

Redundant (half of the quench heaters fired)

QIdecay = 116 MA2s(experimental)

120591119887119906119889119892119890119905=46119898119904

We are tight We need to minimize heaters delayactual value in RB circuits 30 ms

9Susana Izquierdo Bermudez

3 Minimize heaters delay inter-layer heaters

Parameter Case 1

(only OL)Case 6(OL+IL)

OL HF heater delay ms 146 101OL LF heater delay ms 277 195

IL delay ms 565 70MIITs total MA2s 182 152

MIITs after heater effective MA2s 136 117MIITs heater fired until effective MA2s 21 10

Peak temperature in coil K 440 322Peak temperature in heater K 292 260

Δ OL HF QHdelay = - 31 Δ IL Qhdelay = - 88 ΔTmax = - 27

RemarksThermal contact resistances (eg between insulation layers) not included the same scaling factor as the one used to fit the FNAL test data is kept for this simulationThe insulation is a combination of glass fiber and Mica At the moment in the model we use G10

CASE 1 Only Outer Layer Heaters

Heater parameters

bull Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulation

bull Insulation heater2bath = 508 microm kaptonbull Po = 70 Wcm2 =74 ms ΔtQHdelay=5 msbull Non-redundant configuration

Some technical development required before inter-layer heaters become a feasible option

CASE 2 Outer Layer + Inter Layer Heaters

10Susana Izquierdo Bermudez

3 Minimize heaters delay reduce kapton thickness

Parameter Case 1114microm k

Case 250microm k

OL HF heater delay ms 21 14OL LF heater delay ms 335 24

IL delay ms 71 63MIITs total MA2s 176 163

MIITs after heater effective MA2s 122 12MIITs heater fired until effective MA2s 46 4

Peak temperature in coil K 422 367Peak temperature in heater K 208 196

Δ OL HF QHdelay = - 33 ΔTmax = - 13

CASE 1Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kaptonCASE 2Insulation heater2coil = 50 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kapton

Po = 64 Wcm2 (LF) 39 Wcm2 (HF) =31 ms ΔtQHdelay =5ms Non-redundant configurationQuench validation 100mV 10ms

11Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

DESIGN GUIDELINESbull Heaters should cover as many turns as possiblebull Design should be suitable for a 55 m length magnet heating stationsbull Aiming to heater delays lt 20 ms bull Two independent circuits (for redundancy)bull Higher power density in the LF region

Circuit 1Circuit 2

12Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

For long magnets the total heater resistance becomes too high Heating stations2 possible options

Heating stations LARPLQ example wide section = 23 mm narrow section 9 mm

distance between stations 100mm

LHC copper plated solutionMB example 15 mm width 400 mm plated 120 mm un-plated

Qualitative tests at CERN to understand how smooth the transition between narrow and wide section should be in order to avoid high spot temperaturesMore development required to find a solution which combines smooth transition enough coverage and distance in between heater stations small enough to allow fast quench propagation in the longitudinal direction

BASELINE SOLUTION FOR THE FIRST MODEL = COPPER PLATED SOLUTION Thanks to Vladimir Datskov amp Glyn Kirby

13Susana Izquierdo Bermudez

50 60 70 80 90 100 110 120 130 140 15000

200

400

600

800

1000

1200

1400

Low Field Region High Field Region

Heater Current (A)

Pow

er d

ensi

ty (W

cm

2)

Operation area

3 Minimize heaters delay heater design optimization

bull Width -gt Cover as many turns as possible

bull LF 20 mm bull HF 24 mm

bull Power densitybull LF asymp 75 Wcm2

bull HFasymp 55 Wcm2

Even if the operational current is expected to be in the range 100-120 A it would be good to have the possibility to go up to 150 A during short model tests to check the saturation of the system in terms of heater delays

119875119889=1198682119877119908119871

119877=120588 119871119908119905

119875119889=1198682 1205881199082119905

Heater width20 mm LF 24 mm HFρss=7810-7Ωm RRR=134

bull Distance between heater stations -gt quench propagation in between stations asymp 5 msbull LF 90 mmbull HF 130 mm

bull Coverage maximum coverage keeping the resistance within the allowable limits for a 55m magnet (depends on the number of power suppliesheater circuits)

Coverage Distance between stations

wid

th

14Susana Izquierdo Bermudez

OBJECTIVE Stay within LHC standard quench heater supply limits(V = 450 V C=705 mF Ip asymp 85 A but it can safely operate up to 300 A)

V (V)

I (A)

C (mF)

Tau(ms)

Max Energy (kJ)

Power density(Wcm2)

900 120705 55

28 84 (LF)58 (HF)

850 113 25 75 (LF)52 (HF)

For a 55 m magnet and 50 mm coverage

During first short model test Higher currents (up to 150) to check the saturation of the system in terms of heater delay

3 Minimize heaters delay heater design optimization

15Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

Baseline solution

+-+-

-

+

-

+--+

+

50 90130

202

4

Heater strip Heater circuit

If heater delays becomes too high andor current decay too slowhellipwe still canDuplicate the heater coverage (50mm100mm) + parallel circuit

Duplicate the heater coverage (50mm100mm) + independent circuits

We need 2 times more current from the power supply

We duplicate the number of power supplies

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

4Susana Izquierdo Bermudez

Longitudinal quench propagation2D+1 thermal network Study the propagation of an initial resistive zone of 3 cm length in different turnsI = 11850 A Tbath=19KElement size in the longitudinal direction = 1 mmAdaptive time stepping (min = 10-7s max = 10-5s]

2 3 4 5 6 7 8 9 10 11 120

5

10

15

20

25

30

35ROXIE

Experimental

Average field in the conductor (T)lo

ngitu

dina

l pro

paga

tion

ve-

loci

ty (m

s)

Pole turn IL (high field) v asymp 30 msMid-plane turn OL (low field) v asymp 65 ms

The longitudinal quench propagation velocity in MBHSP01 was measured in one of the quenches in the inner-layer pole turn at 45 K using the time-of-flight method as ~27 ms at 73 of SSL at 45 K

2Quench study based on FNAL 11T tests longitudinal quench propagation

Block 572 ms

Block 6134 ms

Experimental data courtesy of Guram Chlachidze

5Susana Izquierdo Bermudez

Insulation heater2coil = 114 microm kapton + 125 microm G10Insulation heater2bath = 508 microm kapton

2Quench study based on FNAL 11T tests Quench Heaters Delay

40 45 50 55 60 65 70 75 800

102030405060708090

measured MBSHP02 roxie MBSHP02measured MBSHP01 roxie MBSHP01

IIss ()

PH d

elay

(ms)

HFU voltage of 400 V ~ 65 Wcm2 peak power density

MBSHP02 Po LF = 65 Wcm2 Po HF=39 Wcm2 =31 ms

Experimental data courtesy of Guram ChlachidzeROXIE quench heater model

heater

Tuning factor (k) on GijTheater2coilbath to fit

experimental and computed heater delays

k=042

6Susana Izquierdo Bermudez

2Quench study based on FNAL 11T tests QI study

I0 = 11850 A Tbath = 19 K

MIITs after heater effective [MA2s]

MIITs from heater fired until effective [MA2s]

OL-IL delay[ms]

PH delay[ms]

Experimental data 108 37 134 asymp27CASE1 OL heaters fired t=0(computed heat transfer from heater to coil) 123 29 425 21

CASE2 OL quenched PH measured delay(OL fully quenched at PH measured delay) 114 38 338 27

Max Temperature [K]

Heaters fired t=0

OL quenched measured delay

Manual trips with the two operating protection heatersDump delay 1000 ms Self-dump Experimental data courtesy of Guram Chlachidze

7Susana Izquierdo Bermudez

Manual trips with the two operating protection heatersDump delay 1000 ms Self-dump

2Quench study based on FNAL 11T tests QI study

Remark MATPRO database material properties MIITs 6 lower for CUDICryocomp database (mainly due to Copper Thermal Conductivity)

httpsespacecernchroxieDocumentationMaterialspdf

084 MIITs difference

Additional time budget 6 ms

Experimental data courtesy of Guram Chlachidze

QI after heaters effective

8Susana Izquierdo Bermudez

2Quench study based on FNAL 11T tests Time budget

120591119887119906119889119892119890119905=119876119868119898119886119909minus119876119868119889119890119888119886119910

119868 02

QImax = 18 MA2s

QIdecay = 108 MA2s

I0 = 11850 A

(experimental)

120591119887119906119889119892119890119905=51119898119904

Detection timebull Time to get over the threshold 3-6 msbull Validation time 10 ms

Heating firing delay 5 ms Heater delay (experimental) 27 ms

Time needed to quench45-48 ms

Non-redundant (all quench heaters fired)

Redundant (half of the quench heaters fired)

QIdecay = 116 MA2s(experimental)

120591119887119906119889119892119890119905=46119898119904

We are tight We need to minimize heaters delayactual value in RB circuits 30 ms

9Susana Izquierdo Bermudez

3 Minimize heaters delay inter-layer heaters

Parameter Case 1

(only OL)Case 6(OL+IL)

OL HF heater delay ms 146 101OL LF heater delay ms 277 195

IL delay ms 565 70MIITs total MA2s 182 152

MIITs after heater effective MA2s 136 117MIITs heater fired until effective MA2s 21 10

Peak temperature in coil K 440 322Peak temperature in heater K 292 260

Δ OL HF QHdelay = - 31 Δ IL Qhdelay = - 88 ΔTmax = - 27

RemarksThermal contact resistances (eg between insulation layers) not included the same scaling factor as the one used to fit the FNAL test data is kept for this simulationThe insulation is a combination of glass fiber and Mica At the moment in the model we use G10

CASE 1 Only Outer Layer Heaters

Heater parameters

bull Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulation

bull Insulation heater2bath = 508 microm kaptonbull Po = 70 Wcm2 =74 ms ΔtQHdelay=5 msbull Non-redundant configuration

Some technical development required before inter-layer heaters become a feasible option

CASE 2 Outer Layer + Inter Layer Heaters

10Susana Izquierdo Bermudez

3 Minimize heaters delay reduce kapton thickness

Parameter Case 1114microm k

Case 250microm k

OL HF heater delay ms 21 14OL LF heater delay ms 335 24

IL delay ms 71 63MIITs total MA2s 176 163

MIITs after heater effective MA2s 122 12MIITs heater fired until effective MA2s 46 4

Peak temperature in coil K 422 367Peak temperature in heater K 208 196

Δ OL HF QHdelay = - 33 ΔTmax = - 13

CASE 1Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kaptonCASE 2Insulation heater2coil = 50 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kapton

Po = 64 Wcm2 (LF) 39 Wcm2 (HF) =31 ms ΔtQHdelay =5ms Non-redundant configurationQuench validation 100mV 10ms

11Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

DESIGN GUIDELINESbull Heaters should cover as many turns as possiblebull Design should be suitable for a 55 m length magnet heating stationsbull Aiming to heater delays lt 20 ms bull Two independent circuits (for redundancy)bull Higher power density in the LF region

Circuit 1Circuit 2

12Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

For long magnets the total heater resistance becomes too high Heating stations2 possible options

Heating stations LARPLQ example wide section = 23 mm narrow section 9 mm

distance between stations 100mm

LHC copper plated solutionMB example 15 mm width 400 mm plated 120 mm un-plated

Qualitative tests at CERN to understand how smooth the transition between narrow and wide section should be in order to avoid high spot temperaturesMore development required to find a solution which combines smooth transition enough coverage and distance in between heater stations small enough to allow fast quench propagation in the longitudinal direction

BASELINE SOLUTION FOR THE FIRST MODEL = COPPER PLATED SOLUTION Thanks to Vladimir Datskov amp Glyn Kirby

13Susana Izquierdo Bermudez

50 60 70 80 90 100 110 120 130 140 15000

200

400

600

800

1000

1200

1400

Low Field Region High Field Region

Heater Current (A)

Pow

er d

ensi

ty (W

cm

2)

Operation area

3 Minimize heaters delay heater design optimization

bull Width -gt Cover as many turns as possible

bull LF 20 mm bull HF 24 mm

bull Power densitybull LF asymp 75 Wcm2

bull HFasymp 55 Wcm2

Even if the operational current is expected to be in the range 100-120 A it would be good to have the possibility to go up to 150 A during short model tests to check the saturation of the system in terms of heater delays

119875119889=1198682119877119908119871

119877=120588 119871119908119905

119875119889=1198682 1205881199082119905

Heater width20 mm LF 24 mm HFρss=7810-7Ωm RRR=134

bull Distance between heater stations -gt quench propagation in between stations asymp 5 msbull LF 90 mmbull HF 130 mm

bull Coverage maximum coverage keeping the resistance within the allowable limits for a 55m magnet (depends on the number of power suppliesheater circuits)

Coverage Distance between stations

wid

th

14Susana Izquierdo Bermudez

OBJECTIVE Stay within LHC standard quench heater supply limits(V = 450 V C=705 mF Ip asymp 85 A but it can safely operate up to 300 A)

V (V)

I (A)

C (mF)

Tau(ms)

Max Energy (kJ)

Power density(Wcm2)

900 120705 55

28 84 (LF)58 (HF)

850 113 25 75 (LF)52 (HF)

For a 55 m magnet and 50 mm coverage

During first short model test Higher currents (up to 150) to check the saturation of the system in terms of heater delay

3 Minimize heaters delay heater design optimization

15Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

Baseline solution

+-+-

-

+

-

+--+

+

50 90130

202

4

Heater strip Heater circuit

If heater delays becomes too high andor current decay too slowhellipwe still canDuplicate the heater coverage (50mm100mm) + parallel circuit

Duplicate the heater coverage (50mm100mm) + independent circuits

We need 2 times more current from the power supply

We duplicate the number of power supplies

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

5Susana Izquierdo Bermudez

Insulation heater2coil = 114 microm kapton + 125 microm G10Insulation heater2bath = 508 microm kapton

2Quench study based on FNAL 11T tests Quench Heaters Delay

40 45 50 55 60 65 70 75 800

102030405060708090

measured MBSHP02 roxie MBSHP02measured MBSHP01 roxie MBSHP01

IIss ()

PH d

elay

(ms)

HFU voltage of 400 V ~ 65 Wcm2 peak power density

MBSHP02 Po LF = 65 Wcm2 Po HF=39 Wcm2 =31 ms

Experimental data courtesy of Guram ChlachidzeROXIE quench heater model

heater

Tuning factor (k) on GijTheater2coilbath to fit

experimental and computed heater delays

k=042

6Susana Izquierdo Bermudez

2Quench study based on FNAL 11T tests QI study

I0 = 11850 A Tbath = 19 K

MIITs after heater effective [MA2s]

MIITs from heater fired until effective [MA2s]

OL-IL delay[ms]

PH delay[ms]

Experimental data 108 37 134 asymp27CASE1 OL heaters fired t=0(computed heat transfer from heater to coil) 123 29 425 21

CASE2 OL quenched PH measured delay(OL fully quenched at PH measured delay) 114 38 338 27

Max Temperature [K]

Heaters fired t=0

OL quenched measured delay

Manual trips with the two operating protection heatersDump delay 1000 ms Self-dump Experimental data courtesy of Guram Chlachidze

7Susana Izquierdo Bermudez

Manual trips with the two operating protection heatersDump delay 1000 ms Self-dump

2Quench study based on FNAL 11T tests QI study

Remark MATPRO database material properties MIITs 6 lower for CUDICryocomp database (mainly due to Copper Thermal Conductivity)

httpsespacecernchroxieDocumentationMaterialspdf

084 MIITs difference

Additional time budget 6 ms

Experimental data courtesy of Guram Chlachidze

QI after heaters effective

8Susana Izquierdo Bermudez

2Quench study based on FNAL 11T tests Time budget

120591119887119906119889119892119890119905=119876119868119898119886119909minus119876119868119889119890119888119886119910

119868 02

QImax = 18 MA2s

QIdecay = 108 MA2s

I0 = 11850 A

(experimental)

120591119887119906119889119892119890119905=51119898119904

Detection timebull Time to get over the threshold 3-6 msbull Validation time 10 ms

Heating firing delay 5 ms Heater delay (experimental) 27 ms

Time needed to quench45-48 ms

Non-redundant (all quench heaters fired)

Redundant (half of the quench heaters fired)

QIdecay = 116 MA2s(experimental)

120591119887119906119889119892119890119905=46119898119904

We are tight We need to minimize heaters delayactual value in RB circuits 30 ms

9Susana Izquierdo Bermudez

3 Minimize heaters delay inter-layer heaters

Parameter Case 1

(only OL)Case 6(OL+IL)

OL HF heater delay ms 146 101OL LF heater delay ms 277 195

IL delay ms 565 70MIITs total MA2s 182 152

MIITs after heater effective MA2s 136 117MIITs heater fired until effective MA2s 21 10

Peak temperature in coil K 440 322Peak temperature in heater K 292 260

Δ OL HF QHdelay = - 31 Δ IL Qhdelay = - 88 ΔTmax = - 27

RemarksThermal contact resistances (eg between insulation layers) not included the same scaling factor as the one used to fit the FNAL test data is kept for this simulationThe insulation is a combination of glass fiber and Mica At the moment in the model we use G10

CASE 1 Only Outer Layer Heaters

Heater parameters

bull Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulation

bull Insulation heater2bath = 508 microm kaptonbull Po = 70 Wcm2 =74 ms ΔtQHdelay=5 msbull Non-redundant configuration

Some technical development required before inter-layer heaters become a feasible option

CASE 2 Outer Layer + Inter Layer Heaters

10Susana Izquierdo Bermudez

3 Minimize heaters delay reduce kapton thickness

Parameter Case 1114microm k

Case 250microm k

OL HF heater delay ms 21 14OL LF heater delay ms 335 24

IL delay ms 71 63MIITs total MA2s 176 163

MIITs after heater effective MA2s 122 12MIITs heater fired until effective MA2s 46 4

Peak temperature in coil K 422 367Peak temperature in heater K 208 196

Δ OL HF QHdelay = - 33 ΔTmax = - 13

CASE 1Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kaptonCASE 2Insulation heater2coil = 50 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kapton

Po = 64 Wcm2 (LF) 39 Wcm2 (HF) =31 ms ΔtQHdelay =5ms Non-redundant configurationQuench validation 100mV 10ms

11Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

DESIGN GUIDELINESbull Heaters should cover as many turns as possiblebull Design should be suitable for a 55 m length magnet heating stationsbull Aiming to heater delays lt 20 ms bull Two independent circuits (for redundancy)bull Higher power density in the LF region

Circuit 1Circuit 2

12Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

For long magnets the total heater resistance becomes too high Heating stations2 possible options

Heating stations LARPLQ example wide section = 23 mm narrow section 9 mm

distance between stations 100mm

LHC copper plated solutionMB example 15 mm width 400 mm plated 120 mm un-plated

Qualitative tests at CERN to understand how smooth the transition between narrow and wide section should be in order to avoid high spot temperaturesMore development required to find a solution which combines smooth transition enough coverage and distance in between heater stations small enough to allow fast quench propagation in the longitudinal direction

BASELINE SOLUTION FOR THE FIRST MODEL = COPPER PLATED SOLUTION Thanks to Vladimir Datskov amp Glyn Kirby

13Susana Izquierdo Bermudez

50 60 70 80 90 100 110 120 130 140 15000

200

400

600

800

1000

1200

1400

Low Field Region High Field Region

Heater Current (A)

Pow

er d

ensi

ty (W

cm

2)

Operation area

3 Minimize heaters delay heater design optimization

bull Width -gt Cover as many turns as possible

bull LF 20 mm bull HF 24 mm

bull Power densitybull LF asymp 75 Wcm2

bull HFasymp 55 Wcm2

Even if the operational current is expected to be in the range 100-120 A it would be good to have the possibility to go up to 150 A during short model tests to check the saturation of the system in terms of heater delays

119875119889=1198682119877119908119871

119877=120588 119871119908119905

119875119889=1198682 1205881199082119905

Heater width20 mm LF 24 mm HFρss=7810-7Ωm RRR=134

bull Distance between heater stations -gt quench propagation in between stations asymp 5 msbull LF 90 mmbull HF 130 mm

bull Coverage maximum coverage keeping the resistance within the allowable limits for a 55m magnet (depends on the number of power suppliesheater circuits)

Coverage Distance between stations

wid

th

14Susana Izquierdo Bermudez

OBJECTIVE Stay within LHC standard quench heater supply limits(V = 450 V C=705 mF Ip asymp 85 A but it can safely operate up to 300 A)

V (V)

I (A)

C (mF)

Tau(ms)

Max Energy (kJ)

Power density(Wcm2)

900 120705 55

28 84 (LF)58 (HF)

850 113 25 75 (LF)52 (HF)

For a 55 m magnet and 50 mm coverage

During first short model test Higher currents (up to 150) to check the saturation of the system in terms of heater delay

3 Minimize heaters delay heater design optimization

15Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

Baseline solution

+-+-

-

+

-

+--+

+

50 90130

202

4

Heater strip Heater circuit

If heater delays becomes too high andor current decay too slowhellipwe still canDuplicate the heater coverage (50mm100mm) + parallel circuit

Duplicate the heater coverage (50mm100mm) + independent circuits

We need 2 times more current from the power supply

We duplicate the number of power supplies

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

6Susana Izquierdo Bermudez

2Quench study based on FNAL 11T tests QI study

I0 = 11850 A Tbath = 19 K

MIITs after heater effective [MA2s]

MIITs from heater fired until effective [MA2s]

OL-IL delay[ms]

PH delay[ms]

Experimental data 108 37 134 asymp27CASE1 OL heaters fired t=0(computed heat transfer from heater to coil) 123 29 425 21

CASE2 OL quenched PH measured delay(OL fully quenched at PH measured delay) 114 38 338 27

Max Temperature [K]

Heaters fired t=0

OL quenched measured delay

Manual trips with the two operating protection heatersDump delay 1000 ms Self-dump Experimental data courtesy of Guram Chlachidze

7Susana Izquierdo Bermudez

Manual trips with the two operating protection heatersDump delay 1000 ms Self-dump

2Quench study based on FNAL 11T tests QI study

Remark MATPRO database material properties MIITs 6 lower for CUDICryocomp database (mainly due to Copper Thermal Conductivity)

httpsespacecernchroxieDocumentationMaterialspdf

084 MIITs difference

Additional time budget 6 ms

Experimental data courtesy of Guram Chlachidze

QI after heaters effective

8Susana Izquierdo Bermudez

2Quench study based on FNAL 11T tests Time budget

120591119887119906119889119892119890119905=119876119868119898119886119909minus119876119868119889119890119888119886119910

119868 02

QImax = 18 MA2s

QIdecay = 108 MA2s

I0 = 11850 A

(experimental)

120591119887119906119889119892119890119905=51119898119904

Detection timebull Time to get over the threshold 3-6 msbull Validation time 10 ms

Heating firing delay 5 ms Heater delay (experimental) 27 ms

Time needed to quench45-48 ms

Non-redundant (all quench heaters fired)

Redundant (half of the quench heaters fired)

QIdecay = 116 MA2s(experimental)

120591119887119906119889119892119890119905=46119898119904

We are tight We need to minimize heaters delayactual value in RB circuits 30 ms

9Susana Izquierdo Bermudez

3 Minimize heaters delay inter-layer heaters

Parameter Case 1

(only OL)Case 6(OL+IL)

OL HF heater delay ms 146 101OL LF heater delay ms 277 195

IL delay ms 565 70MIITs total MA2s 182 152

MIITs after heater effective MA2s 136 117MIITs heater fired until effective MA2s 21 10

Peak temperature in coil K 440 322Peak temperature in heater K 292 260

Δ OL HF QHdelay = - 31 Δ IL Qhdelay = - 88 ΔTmax = - 27

RemarksThermal contact resistances (eg between insulation layers) not included the same scaling factor as the one used to fit the FNAL test data is kept for this simulationThe insulation is a combination of glass fiber and Mica At the moment in the model we use G10

CASE 1 Only Outer Layer Heaters

Heater parameters

bull Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulation

bull Insulation heater2bath = 508 microm kaptonbull Po = 70 Wcm2 =74 ms ΔtQHdelay=5 msbull Non-redundant configuration

Some technical development required before inter-layer heaters become a feasible option

CASE 2 Outer Layer + Inter Layer Heaters

10Susana Izquierdo Bermudez

3 Minimize heaters delay reduce kapton thickness

Parameter Case 1114microm k

Case 250microm k

OL HF heater delay ms 21 14OL LF heater delay ms 335 24

IL delay ms 71 63MIITs total MA2s 176 163

MIITs after heater effective MA2s 122 12MIITs heater fired until effective MA2s 46 4

Peak temperature in coil K 422 367Peak temperature in heater K 208 196

Δ OL HF QHdelay = - 33 ΔTmax = - 13

CASE 1Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kaptonCASE 2Insulation heater2coil = 50 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kapton

Po = 64 Wcm2 (LF) 39 Wcm2 (HF) =31 ms ΔtQHdelay =5ms Non-redundant configurationQuench validation 100mV 10ms

11Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

DESIGN GUIDELINESbull Heaters should cover as many turns as possiblebull Design should be suitable for a 55 m length magnet heating stationsbull Aiming to heater delays lt 20 ms bull Two independent circuits (for redundancy)bull Higher power density in the LF region

Circuit 1Circuit 2

12Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

For long magnets the total heater resistance becomes too high Heating stations2 possible options

Heating stations LARPLQ example wide section = 23 mm narrow section 9 mm

distance between stations 100mm

LHC copper plated solutionMB example 15 mm width 400 mm plated 120 mm un-plated

Qualitative tests at CERN to understand how smooth the transition between narrow and wide section should be in order to avoid high spot temperaturesMore development required to find a solution which combines smooth transition enough coverage and distance in between heater stations small enough to allow fast quench propagation in the longitudinal direction

BASELINE SOLUTION FOR THE FIRST MODEL = COPPER PLATED SOLUTION Thanks to Vladimir Datskov amp Glyn Kirby

13Susana Izquierdo Bermudez

50 60 70 80 90 100 110 120 130 140 15000

200

400

600

800

1000

1200

1400

Low Field Region High Field Region

Heater Current (A)

Pow

er d

ensi

ty (W

cm

2)

Operation area

3 Minimize heaters delay heater design optimization

bull Width -gt Cover as many turns as possible

bull LF 20 mm bull HF 24 mm

bull Power densitybull LF asymp 75 Wcm2

bull HFasymp 55 Wcm2

Even if the operational current is expected to be in the range 100-120 A it would be good to have the possibility to go up to 150 A during short model tests to check the saturation of the system in terms of heater delays

119875119889=1198682119877119908119871

119877=120588 119871119908119905

119875119889=1198682 1205881199082119905

Heater width20 mm LF 24 mm HFρss=7810-7Ωm RRR=134

bull Distance between heater stations -gt quench propagation in between stations asymp 5 msbull LF 90 mmbull HF 130 mm

bull Coverage maximum coverage keeping the resistance within the allowable limits for a 55m magnet (depends on the number of power suppliesheater circuits)

Coverage Distance between stations

wid

th

14Susana Izquierdo Bermudez

OBJECTIVE Stay within LHC standard quench heater supply limits(V = 450 V C=705 mF Ip asymp 85 A but it can safely operate up to 300 A)

V (V)

I (A)

C (mF)

Tau(ms)

Max Energy (kJ)

Power density(Wcm2)

900 120705 55

28 84 (LF)58 (HF)

850 113 25 75 (LF)52 (HF)

For a 55 m magnet and 50 mm coverage

During first short model test Higher currents (up to 150) to check the saturation of the system in terms of heater delay

3 Minimize heaters delay heater design optimization

15Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

Baseline solution

+-+-

-

+

-

+--+

+

50 90130

202

4

Heater strip Heater circuit

If heater delays becomes too high andor current decay too slowhellipwe still canDuplicate the heater coverage (50mm100mm) + parallel circuit

Duplicate the heater coverage (50mm100mm) + independent circuits

We need 2 times more current from the power supply

We duplicate the number of power supplies

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

7Susana Izquierdo Bermudez

Manual trips with the two operating protection heatersDump delay 1000 ms Self-dump

2Quench study based on FNAL 11T tests QI study

Remark MATPRO database material properties MIITs 6 lower for CUDICryocomp database (mainly due to Copper Thermal Conductivity)

httpsespacecernchroxieDocumentationMaterialspdf

084 MIITs difference

Additional time budget 6 ms

Experimental data courtesy of Guram Chlachidze

QI after heaters effective

8Susana Izquierdo Bermudez

2Quench study based on FNAL 11T tests Time budget

120591119887119906119889119892119890119905=119876119868119898119886119909minus119876119868119889119890119888119886119910

119868 02

QImax = 18 MA2s

QIdecay = 108 MA2s

I0 = 11850 A

(experimental)

120591119887119906119889119892119890119905=51119898119904

Detection timebull Time to get over the threshold 3-6 msbull Validation time 10 ms

Heating firing delay 5 ms Heater delay (experimental) 27 ms

Time needed to quench45-48 ms

Non-redundant (all quench heaters fired)

Redundant (half of the quench heaters fired)

QIdecay = 116 MA2s(experimental)

120591119887119906119889119892119890119905=46119898119904

We are tight We need to minimize heaters delayactual value in RB circuits 30 ms

9Susana Izquierdo Bermudez

3 Minimize heaters delay inter-layer heaters

Parameter Case 1

(only OL)Case 6(OL+IL)

OL HF heater delay ms 146 101OL LF heater delay ms 277 195

IL delay ms 565 70MIITs total MA2s 182 152

MIITs after heater effective MA2s 136 117MIITs heater fired until effective MA2s 21 10

Peak temperature in coil K 440 322Peak temperature in heater K 292 260

Δ OL HF QHdelay = - 31 Δ IL Qhdelay = - 88 ΔTmax = - 27

RemarksThermal contact resistances (eg between insulation layers) not included the same scaling factor as the one used to fit the FNAL test data is kept for this simulationThe insulation is a combination of glass fiber and Mica At the moment in the model we use G10

CASE 1 Only Outer Layer Heaters

Heater parameters

bull Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulation

bull Insulation heater2bath = 508 microm kaptonbull Po = 70 Wcm2 =74 ms ΔtQHdelay=5 msbull Non-redundant configuration

Some technical development required before inter-layer heaters become a feasible option

CASE 2 Outer Layer + Inter Layer Heaters

10Susana Izquierdo Bermudez

3 Minimize heaters delay reduce kapton thickness

Parameter Case 1114microm k

Case 250microm k

OL HF heater delay ms 21 14OL LF heater delay ms 335 24

IL delay ms 71 63MIITs total MA2s 176 163

MIITs after heater effective MA2s 122 12MIITs heater fired until effective MA2s 46 4

Peak temperature in coil K 422 367Peak temperature in heater K 208 196

Δ OL HF QHdelay = - 33 ΔTmax = - 13

CASE 1Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kaptonCASE 2Insulation heater2coil = 50 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kapton

Po = 64 Wcm2 (LF) 39 Wcm2 (HF) =31 ms ΔtQHdelay =5ms Non-redundant configurationQuench validation 100mV 10ms

11Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

DESIGN GUIDELINESbull Heaters should cover as many turns as possiblebull Design should be suitable for a 55 m length magnet heating stationsbull Aiming to heater delays lt 20 ms bull Two independent circuits (for redundancy)bull Higher power density in the LF region

Circuit 1Circuit 2

12Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

For long magnets the total heater resistance becomes too high Heating stations2 possible options

Heating stations LARPLQ example wide section = 23 mm narrow section 9 mm

distance between stations 100mm

LHC copper plated solutionMB example 15 mm width 400 mm plated 120 mm un-plated

Qualitative tests at CERN to understand how smooth the transition between narrow and wide section should be in order to avoid high spot temperaturesMore development required to find a solution which combines smooth transition enough coverage and distance in between heater stations small enough to allow fast quench propagation in the longitudinal direction

BASELINE SOLUTION FOR THE FIRST MODEL = COPPER PLATED SOLUTION Thanks to Vladimir Datskov amp Glyn Kirby

13Susana Izquierdo Bermudez

50 60 70 80 90 100 110 120 130 140 15000

200

400

600

800

1000

1200

1400

Low Field Region High Field Region

Heater Current (A)

Pow

er d

ensi

ty (W

cm

2)

Operation area

3 Minimize heaters delay heater design optimization

bull Width -gt Cover as many turns as possible

bull LF 20 mm bull HF 24 mm

bull Power densitybull LF asymp 75 Wcm2

bull HFasymp 55 Wcm2

Even if the operational current is expected to be in the range 100-120 A it would be good to have the possibility to go up to 150 A during short model tests to check the saturation of the system in terms of heater delays

119875119889=1198682119877119908119871

119877=120588 119871119908119905

119875119889=1198682 1205881199082119905

Heater width20 mm LF 24 mm HFρss=7810-7Ωm RRR=134

bull Distance between heater stations -gt quench propagation in between stations asymp 5 msbull LF 90 mmbull HF 130 mm

bull Coverage maximum coverage keeping the resistance within the allowable limits for a 55m magnet (depends on the number of power suppliesheater circuits)

Coverage Distance between stations

wid

th

14Susana Izquierdo Bermudez

OBJECTIVE Stay within LHC standard quench heater supply limits(V = 450 V C=705 mF Ip asymp 85 A but it can safely operate up to 300 A)

V (V)

I (A)

C (mF)

Tau(ms)

Max Energy (kJ)

Power density(Wcm2)

900 120705 55

28 84 (LF)58 (HF)

850 113 25 75 (LF)52 (HF)

For a 55 m magnet and 50 mm coverage

During first short model test Higher currents (up to 150) to check the saturation of the system in terms of heater delay

3 Minimize heaters delay heater design optimization

15Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

Baseline solution

+-+-

-

+

-

+--+

+

50 90130

202

4

Heater strip Heater circuit

If heater delays becomes too high andor current decay too slowhellipwe still canDuplicate the heater coverage (50mm100mm) + parallel circuit

Duplicate the heater coverage (50mm100mm) + independent circuits

We need 2 times more current from the power supply

We duplicate the number of power supplies

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

8Susana Izquierdo Bermudez

2Quench study based on FNAL 11T tests Time budget

120591119887119906119889119892119890119905=119876119868119898119886119909minus119876119868119889119890119888119886119910

119868 02

QImax = 18 MA2s

QIdecay = 108 MA2s

I0 = 11850 A

(experimental)

120591119887119906119889119892119890119905=51119898119904

Detection timebull Time to get over the threshold 3-6 msbull Validation time 10 ms

Heating firing delay 5 ms Heater delay (experimental) 27 ms

Time needed to quench45-48 ms

Non-redundant (all quench heaters fired)

Redundant (half of the quench heaters fired)

QIdecay = 116 MA2s(experimental)

120591119887119906119889119892119890119905=46119898119904

We are tight We need to minimize heaters delayactual value in RB circuits 30 ms

9Susana Izquierdo Bermudez

3 Minimize heaters delay inter-layer heaters

Parameter Case 1

(only OL)Case 6(OL+IL)

OL HF heater delay ms 146 101OL LF heater delay ms 277 195

IL delay ms 565 70MIITs total MA2s 182 152

MIITs after heater effective MA2s 136 117MIITs heater fired until effective MA2s 21 10

Peak temperature in coil K 440 322Peak temperature in heater K 292 260

Δ OL HF QHdelay = - 31 Δ IL Qhdelay = - 88 ΔTmax = - 27

RemarksThermal contact resistances (eg between insulation layers) not included the same scaling factor as the one used to fit the FNAL test data is kept for this simulationThe insulation is a combination of glass fiber and Mica At the moment in the model we use G10

CASE 1 Only Outer Layer Heaters

Heater parameters

bull Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulation

bull Insulation heater2bath = 508 microm kaptonbull Po = 70 Wcm2 =74 ms ΔtQHdelay=5 msbull Non-redundant configuration

Some technical development required before inter-layer heaters become a feasible option

CASE 2 Outer Layer + Inter Layer Heaters

10Susana Izquierdo Bermudez

3 Minimize heaters delay reduce kapton thickness

Parameter Case 1114microm k

Case 250microm k

OL HF heater delay ms 21 14OL LF heater delay ms 335 24

IL delay ms 71 63MIITs total MA2s 176 163

MIITs after heater effective MA2s 122 12MIITs heater fired until effective MA2s 46 4

Peak temperature in coil K 422 367Peak temperature in heater K 208 196

Δ OL HF QHdelay = - 33 ΔTmax = - 13

CASE 1Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kaptonCASE 2Insulation heater2coil = 50 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kapton

Po = 64 Wcm2 (LF) 39 Wcm2 (HF) =31 ms ΔtQHdelay =5ms Non-redundant configurationQuench validation 100mV 10ms

11Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

DESIGN GUIDELINESbull Heaters should cover as many turns as possiblebull Design should be suitable for a 55 m length magnet heating stationsbull Aiming to heater delays lt 20 ms bull Two independent circuits (for redundancy)bull Higher power density in the LF region

Circuit 1Circuit 2

12Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

For long magnets the total heater resistance becomes too high Heating stations2 possible options

Heating stations LARPLQ example wide section = 23 mm narrow section 9 mm

distance between stations 100mm

LHC copper plated solutionMB example 15 mm width 400 mm plated 120 mm un-plated

Qualitative tests at CERN to understand how smooth the transition between narrow and wide section should be in order to avoid high spot temperaturesMore development required to find a solution which combines smooth transition enough coverage and distance in between heater stations small enough to allow fast quench propagation in the longitudinal direction

BASELINE SOLUTION FOR THE FIRST MODEL = COPPER PLATED SOLUTION Thanks to Vladimir Datskov amp Glyn Kirby

13Susana Izquierdo Bermudez

50 60 70 80 90 100 110 120 130 140 15000

200

400

600

800

1000

1200

1400

Low Field Region High Field Region

Heater Current (A)

Pow

er d

ensi

ty (W

cm

2)

Operation area

3 Minimize heaters delay heater design optimization

bull Width -gt Cover as many turns as possible

bull LF 20 mm bull HF 24 mm

bull Power densitybull LF asymp 75 Wcm2

bull HFasymp 55 Wcm2

Even if the operational current is expected to be in the range 100-120 A it would be good to have the possibility to go up to 150 A during short model tests to check the saturation of the system in terms of heater delays

119875119889=1198682119877119908119871

119877=120588 119871119908119905

119875119889=1198682 1205881199082119905

Heater width20 mm LF 24 mm HFρss=7810-7Ωm RRR=134

bull Distance between heater stations -gt quench propagation in between stations asymp 5 msbull LF 90 mmbull HF 130 mm

bull Coverage maximum coverage keeping the resistance within the allowable limits for a 55m magnet (depends on the number of power suppliesheater circuits)

Coverage Distance between stations

wid

th

14Susana Izquierdo Bermudez

OBJECTIVE Stay within LHC standard quench heater supply limits(V = 450 V C=705 mF Ip asymp 85 A but it can safely operate up to 300 A)

V (V)

I (A)

C (mF)

Tau(ms)

Max Energy (kJ)

Power density(Wcm2)

900 120705 55

28 84 (LF)58 (HF)

850 113 25 75 (LF)52 (HF)

For a 55 m magnet and 50 mm coverage

During first short model test Higher currents (up to 150) to check the saturation of the system in terms of heater delay

3 Minimize heaters delay heater design optimization

15Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

Baseline solution

+-+-

-

+

-

+--+

+

50 90130

202

4

Heater strip Heater circuit

If heater delays becomes too high andor current decay too slowhellipwe still canDuplicate the heater coverage (50mm100mm) + parallel circuit

Duplicate the heater coverage (50mm100mm) + independent circuits

We need 2 times more current from the power supply

We duplicate the number of power supplies

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

9Susana Izquierdo Bermudez

3 Minimize heaters delay inter-layer heaters

Parameter Case 1

(only OL)Case 6(OL+IL)

OL HF heater delay ms 146 101OL LF heater delay ms 277 195

IL delay ms 565 70MIITs total MA2s 182 152

MIITs after heater effective MA2s 136 117MIITs heater fired until effective MA2s 21 10

Peak temperature in coil K 440 322Peak temperature in heater K 292 260

Δ OL HF QHdelay = - 31 Δ IL Qhdelay = - 88 ΔTmax = - 27

RemarksThermal contact resistances (eg between insulation layers) not included the same scaling factor as the one used to fit the FNAL test data is kept for this simulationThe insulation is a combination of glass fiber and Mica At the moment in the model we use G10

CASE 1 Only Outer Layer Heaters

Heater parameters

bull Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulation

bull Insulation heater2bath = 508 microm kaptonbull Po = 70 Wcm2 =74 ms ΔtQHdelay=5 msbull Non-redundant configuration

Some technical development required before inter-layer heaters become a feasible option

CASE 2 Outer Layer + Inter Layer Heaters

10Susana Izquierdo Bermudez

3 Minimize heaters delay reduce kapton thickness

Parameter Case 1114microm k

Case 250microm k

OL HF heater delay ms 21 14OL LF heater delay ms 335 24

IL delay ms 71 63MIITs total MA2s 176 163

MIITs after heater effective MA2s 122 12MIITs heater fired until effective MA2s 46 4

Peak temperature in coil K 422 367Peak temperature in heater K 208 196

Δ OL HF QHdelay = - 33 ΔTmax = - 13

CASE 1Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kaptonCASE 2Insulation heater2coil = 50 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kapton

Po = 64 Wcm2 (LF) 39 Wcm2 (HF) =31 ms ΔtQHdelay =5ms Non-redundant configurationQuench validation 100mV 10ms

11Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

DESIGN GUIDELINESbull Heaters should cover as many turns as possiblebull Design should be suitable for a 55 m length magnet heating stationsbull Aiming to heater delays lt 20 ms bull Two independent circuits (for redundancy)bull Higher power density in the LF region

Circuit 1Circuit 2

12Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

For long magnets the total heater resistance becomes too high Heating stations2 possible options

Heating stations LARPLQ example wide section = 23 mm narrow section 9 mm

distance between stations 100mm

LHC copper plated solutionMB example 15 mm width 400 mm plated 120 mm un-plated

Qualitative tests at CERN to understand how smooth the transition between narrow and wide section should be in order to avoid high spot temperaturesMore development required to find a solution which combines smooth transition enough coverage and distance in between heater stations small enough to allow fast quench propagation in the longitudinal direction

BASELINE SOLUTION FOR THE FIRST MODEL = COPPER PLATED SOLUTION Thanks to Vladimir Datskov amp Glyn Kirby

13Susana Izquierdo Bermudez

50 60 70 80 90 100 110 120 130 140 15000

200

400

600

800

1000

1200

1400

Low Field Region High Field Region

Heater Current (A)

Pow

er d

ensi

ty (W

cm

2)

Operation area

3 Minimize heaters delay heater design optimization

bull Width -gt Cover as many turns as possible

bull LF 20 mm bull HF 24 mm

bull Power densitybull LF asymp 75 Wcm2

bull HFasymp 55 Wcm2

Even if the operational current is expected to be in the range 100-120 A it would be good to have the possibility to go up to 150 A during short model tests to check the saturation of the system in terms of heater delays

119875119889=1198682119877119908119871

119877=120588 119871119908119905

119875119889=1198682 1205881199082119905

Heater width20 mm LF 24 mm HFρss=7810-7Ωm RRR=134

bull Distance between heater stations -gt quench propagation in between stations asymp 5 msbull LF 90 mmbull HF 130 mm

bull Coverage maximum coverage keeping the resistance within the allowable limits for a 55m magnet (depends on the number of power suppliesheater circuits)

Coverage Distance between stations

wid

th

14Susana Izquierdo Bermudez

OBJECTIVE Stay within LHC standard quench heater supply limits(V = 450 V C=705 mF Ip asymp 85 A but it can safely operate up to 300 A)

V (V)

I (A)

C (mF)

Tau(ms)

Max Energy (kJ)

Power density(Wcm2)

900 120705 55

28 84 (LF)58 (HF)

850 113 25 75 (LF)52 (HF)

For a 55 m magnet and 50 mm coverage

During first short model test Higher currents (up to 150) to check the saturation of the system in terms of heater delay

3 Minimize heaters delay heater design optimization

15Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

Baseline solution

+-+-

-

+

-

+--+

+

50 90130

202

4

Heater strip Heater circuit

If heater delays becomes too high andor current decay too slowhellipwe still canDuplicate the heater coverage (50mm100mm) + parallel circuit

Duplicate the heater coverage (50mm100mm) + independent circuits

We need 2 times more current from the power supply

We duplicate the number of power supplies

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

10Susana Izquierdo Bermudez

3 Minimize heaters delay reduce kapton thickness

Parameter Case 1114microm k

Case 250microm k

OL HF heater delay ms 21 14OL LF heater delay ms 335 24

IL delay ms 71 63MIITs total MA2s 176 163

MIITs after heater effective MA2s 122 12MIITs heater fired until effective MA2s 46 4

Peak temperature in coil K 422 367Peak temperature in heater K 208 196

Δ OL HF QHdelay = - 33 ΔTmax = - 13

CASE 1Insulation heater2coil = 114 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kaptonCASE 2Insulation heater2coil = 50 microm kapton + 125 microm G10 + conductor insulationInsulation heater2bath = 508 microm kapton

Po = 64 Wcm2 (LF) 39 Wcm2 (HF) =31 ms ΔtQHdelay =5ms Non-redundant configurationQuench validation 100mV 10ms

11Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

DESIGN GUIDELINESbull Heaters should cover as many turns as possiblebull Design should be suitable for a 55 m length magnet heating stationsbull Aiming to heater delays lt 20 ms bull Two independent circuits (for redundancy)bull Higher power density in the LF region

Circuit 1Circuit 2

12Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

For long magnets the total heater resistance becomes too high Heating stations2 possible options

Heating stations LARPLQ example wide section = 23 mm narrow section 9 mm

distance between stations 100mm

LHC copper plated solutionMB example 15 mm width 400 mm plated 120 mm un-plated

Qualitative tests at CERN to understand how smooth the transition between narrow and wide section should be in order to avoid high spot temperaturesMore development required to find a solution which combines smooth transition enough coverage and distance in between heater stations small enough to allow fast quench propagation in the longitudinal direction

BASELINE SOLUTION FOR THE FIRST MODEL = COPPER PLATED SOLUTION Thanks to Vladimir Datskov amp Glyn Kirby

13Susana Izquierdo Bermudez

50 60 70 80 90 100 110 120 130 140 15000

200

400

600

800

1000

1200

1400

Low Field Region High Field Region

Heater Current (A)

Pow

er d

ensi

ty (W

cm

2)

Operation area

3 Minimize heaters delay heater design optimization

bull Width -gt Cover as many turns as possible

bull LF 20 mm bull HF 24 mm

bull Power densitybull LF asymp 75 Wcm2

bull HFasymp 55 Wcm2

Even if the operational current is expected to be in the range 100-120 A it would be good to have the possibility to go up to 150 A during short model tests to check the saturation of the system in terms of heater delays

119875119889=1198682119877119908119871

119877=120588 119871119908119905

119875119889=1198682 1205881199082119905

Heater width20 mm LF 24 mm HFρss=7810-7Ωm RRR=134

bull Distance between heater stations -gt quench propagation in between stations asymp 5 msbull LF 90 mmbull HF 130 mm

bull Coverage maximum coverage keeping the resistance within the allowable limits for a 55m magnet (depends on the number of power suppliesheater circuits)

Coverage Distance between stations

wid

th

14Susana Izquierdo Bermudez

OBJECTIVE Stay within LHC standard quench heater supply limits(V = 450 V C=705 mF Ip asymp 85 A but it can safely operate up to 300 A)

V (V)

I (A)

C (mF)

Tau(ms)

Max Energy (kJ)

Power density(Wcm2)

900 120705 55

28 84 (LF)58 (HF)

850 113 25 75 (LF)52 (HF)

For a 55 m magnet and 50 mm coverage

During first short model test Higher currents (up to 150) to check the saturation of the system in terms of heater delay

3 Minimize heaters delay heater design optimization

15Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

Baseline solution

+-+-

-

+

-

+--+

+

50 90130

202

4

Heater strip Heater circuit

If heater delays becomes too high andor current decay too slowhellipwe still canDuplicate the heater coverage (50mm100mm) + parallel circuit

Duplicate the heater coverage (50mm100mm) + independent circuits

We need 2 times more current from the power supply

We duplicate the number of power supplies

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

11Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

DESIGN GUIDELINESbull Heaters should cover as many turns as possiblebull Design should be suitable for a 55 m length magnet heating stationsbull Aiming to heater delays lt 20 ms bull Two independent circuits (for redundancy)bull Higher power density in the LF region

Circuit 1Circuit 2

12Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

For long magnets the total heater resistance becomes too high Heating stations2 possible options

Heating stations LARPLQ example wide section = 23 mm narrow section 9 mm

distance between stations 100mm

LHC copper plated solutionMB example 15 mm width 400 mm plated 120 mm un-plated

Qualitative tests at CERN to understand how smooth the transition between narrow and wide section should be in order to avoid high spot temperaturesMore development required to find a solution which combines smooth transition enough coverage and distance in between heater stations small enough to allow fast quench propagation in the longitudinal direction

BASELINE SOLUTION FOR THE FIRST MODEL = COPPER PLATED SOLUTION Thanks to Vladimir Datskov amp Glyn Kirby

13Susana Izquierdo Bermudez

50 60 70 80 90 100 110 120 130 140 15000

200

400

600

800

1000

1200

1400

Low Field Region High Field Region

Heater Current (A)

Pow

er d

ensi

ty (W

cm

2)

Operation area

3 Minimize heaters delay heater design optimization

bull Width -gt Cover as many turns as possible

bull LF 20 mm bull HF 24 mm

bull Power densitybull LF asymp 75 Wcm2

bull HFasymp 55 Wcm2

Even if the operational current is expected to be in the range 100-120 A it would be good to have the possibility to go up to 150 A during short model tests to check the saturation of the system in terms of heater delays

119875119889=1198682119877119908119871

119877=120588 119871119908119905

119875119889=1198682 1205881199082119905

Heater width20 mm LF 24 mm HFρss=7810-7Ωm RRR=134

bull Distance between heater stations -gt quench propagation in between stations asymp 5 msbull LF 90 mmbull HF 130 mm

bull Coverage maximum coverage keeping the resistance within the allowable limits for a 55m magnet (depends on the number of power suppliesheater circuits)

Coverage Distance between stations

wid

th

14Susana Izquierdo Bermudez

OBJECTIVE Stay within LHC standard quench heater supply limits(V = 450 V C=705 mF Ip asymp 85 A but it can safely operate up to 300 A)

V (V)

I (A)

C (mF)

Tau(ms)

Max Energy (kJ)

Power density(Wcm2)

900 120705 55

28 84 (LF)58 (HF)

850 113 25 75 (LF)52 (HF)

For a 55 m magnet and 50 mm coverage

During first short model test Higher currents (up to 150) to check the saturation of the system in terms of heater delay

3 Minimize heaters delay heater design optimization

15Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

Baseline solution

+-+-

-

+

-

+--+

+

50 90130

202

4

Heater strip Heater circuit

If heater delays becomes too high andor current decay too slowhellipwe still canDuplicate the heater coverage (50mm100mm) + parallel circuit

Duplicate the heater coverage (50mm100mm) + independent circuits

We need 2 times more current from the power supply

We duplicate the number of power supplies

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

12Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

For long magnets the total heater resistance becomes too high Heating stations2 possible options

Heating stations LARPLQ example wide section = 23 mm narrow section 9 mm

distance between stations 100mm

LHC copper plated solutionMB example 15 mm width 400 mm plated 120 mm un-plated

Qualitative tests at CERN to understand how smooth the transition between narrow and wide section should be in order to avoid high spot temperaturesMore development required to find a solution which combines smooth transition enough coverage and distance in between heater stations small enough to allow fast quench propagation in the longitudinal direction

BASELINE SOLUTION FOR THE FIRST MODEL = COPPER PLATED SOLUTION Thanks to Vladimir Datskov amp Glyn Kirby

13Susana Izquierdo Bermudez

50 60 70 80 90 100 110 120 130 140 15000

200

400

600

800

1000

1200

1400

Low Field Region High Field Region

Heater Current (A)

Pow

er d

ensi

ty (W

cm

2)

Operation area

3 Minimize heaters delay heater design optimization

bull Width -gt Cover as many turns as possible

bull LF 20 mm bull HF 24 mm

bull Power densitybull LF asymp 75 Wcm2

bull HFasymp 55 Wcm2

Even if the operational current is expected to be in the range 100-120 A it would be good to have the possibility to go up to 150 A during short model tests to check the saturation of the system in terms of heater delays

119875119889=1198682119877119908119871

119877=120588 119871119908119905

119875119889=1198682 1205881199082119905

Heater width20 mm LF 24 mm HFρss=7810-7Ωm RRR=134

bull Distance between heater stations -gt quench propagation in between stations asymp 5 msbull LF 90 mmbull HF 130 mm

bull Coverage maximum coverage keeping the resistance within the allowable limits for a 55m magnet (depends on the number of power suppliesheater circuits)

Coverage Distance between stations

wid

th

14Susana Izquierdo Bermudez

OBJECTIVE Stay within LHC standard quench heater supply limits(V = 450 V C=705 mF Ip asymp 85 A but it can safely operate up to 300 A)

V (V)

I (A)

C (mF)

Tau(ms)

Max Energy (kJ)

Power density(Wcm2)

900 120705 55

28 84 (LF)58 (HF)

850 113 25 75 (LF)52 (HF)

For a 55 m magnet and 50 mm coverage

During first short model test Higher currents (up to 150) to check the saturation of the system in terms of heater delay

3 Minimize heaters delay heater design optimization

15Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

Baseline solution

+-+-

-

+

-

+--+

+

50 90130

202

4

Heater strip Heater circuit

If heater delays becomes too high andor current decay too slowhellipwe still canDuplicate the heater coverage (50mm100mm) + parallel circuit

Duplicate the heater coverage (50mm100mm) + independent circuits

We need 2 times more current from the power supply

We duplicate the number of power supplies

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

13Susana Izquierdo Bermudez

50 60 70 80 90 100 110 120 130 140 15000

200

400

600

800

1000

1200

1400

Low Field Region High Field Region

Heater Current (A)

Pow

er d

ensi

ty (W

cm

2)

Operation area

3 Minimize heaters delay heater design optimization

bull Width -gt Cover as many turns as possible

bull LF 20 mm bull HF 24 mm

bull Power densitybull LF asymp 75 Wcm2

bull HFasymp 55 Wcm2

Even if the operational current is expected to be in the range 100-120 A it would be good to have the possibility to go up to 150 A during short model tests to check the saturation of the system in terms of heater delays

119875119889=1198682119877119908119871

119877=120588 119871119908119905

119875119889=1198682 1205881199082119905

Heater width20 mm LF 24 mm HFρss=7810-7Ωm RRR=134

bull Distance between heater stations -gt quench propagation in between stations asymp 5 msbull LF 90 mmbull HF 130 mm

bull Coverage maximum coverage keeping the resistance within the allowable limits for a 55m magnet (depends on the number of power suppliesheater circuits)

Coverage Distance between stations

wid

th

14Susana Izquierdo Bermudez

OBJECTIVE Stay within LHC standard quench heater supply limits(V = 450 V C=705 mF Ip asymp 85 A but it can safely operate up to 300 A)

V (V)

I (A)

C (mF)

Tau(ms)

Max Energy (kJ)

Power density(Wcm2)

900 120705 55

28 84 (LF)58 (HF)

850 113 25 75 (LF)52 (HF)

For a 55 m magnet and 50 mm coverage

During first short model test Higher currents (up to 150) to check the saturation of the system in terms of heater delay

3 Minimize heaters delay heater design optimization

15Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

Baseline solution

+-+-

-

+

-

+--+

+

50 90130

202

4

Heater strip Heater circuit

If heater delays becomes too high andor current decay too slowhellipwe still canDuplicate the heater coverage (50mm100mm) + parallel circuit

Duplicate the heater coverage (50mm100mm) + independent circuits

We need 2 times more current from the power supply

We duplicate the number of power supplies

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

14Susana Izquierdo Bermudez

OBJECTIVE Stay within LHC standard quench heater supply limits(V = 450 V C=705 mF Ip asymp 85 A but it can safely operate up to 300 A)

V (V)

I (A)

C (mF)

Tau(ms)

Max Energy (kJ)

Power density(Wcm2)

900 120705 55

28 84 (LF)58 (HF)

850 113 25 75 (LF)52 (HF)

For a 55 m magnet and 50 mm coverage

During first short model test Higher currents (up to 150) to check the saturation of the system in terms of heater delay

3 Minimize heaters delay heater design optimization

15Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

Baseline solution

+-+-

-

+

-

+--+

+

50 90130

202

4

Heater strip Heater circuit

If heater delays becomes too high andor current decay too slowhellipwe still canDuplicate the heater coverage (50mm100mm) + parallel circuit

Duplicate the heater coverage (50mm100mm) + independent circuits

We need 2 times more current from the power supply

We duplicate the number of power supplies

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

15Susana Izquierdo Bermudez

3 Minimize heaters delay heater design optimization

Baseline solution

+-+-

-

+

-

+--+

+

50 90130

202

4

Heater strip Heater circuit

If heater delays becomes too high andor current decay too slowhellipwe still canDuplicate the heater coverage (50mm100mm) + parallel circuit

Duplicate the heater coverage (50mm100mm) + independent circuits

We need 2 times more current from the power supply

We duplicate the number of power supplies

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

16Susana Izquierdo Bermudez

3D simulation with heater stations

1 MIITs difference

Time budget 7 ms higher in case of full coverage

Full coverage vs heating stations

3 Minimize heaters delay heater design optimization

50 90130

202

4

Remark ROXIE does not have adaptive mesh tracking (which is a must for practical quench simulation)

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

17Susana Izquierdo Bermudez

4 Quench performance under accelerator conditions (I)

bull Quench initiation and protectionbull INZ in the pole turn inner layer (high field) 3 cm length bull Quench detection at 100 mV (time required to reach this threshold from quench initiation = 3 ms) 1

bull Validation time = 10 msbull Quench heaters (only outer layer heaters)

bull Heater-firing delay = 5 ms (time from firing the heaters to heaters effective)bull Po = 84 Wcm2 (LF) 58 Wcm2 (HF) tau = 55 ms bull Insulation heater2coil = 50 microm kapton + 125 microm G10 Insulation heater2bath = 508 microm kaptonbull Redundant configuration (only half of the heaters fired)

bull Cable eddy-currents are considered using Rc = 30 μΩ for the cross-over resistance in a cored cable and 03 μΩ for Ra

bull Electrical network

1 The results presented later on correspond to a 2D simulation (X-Sec) 2D+1 thermal network is used only for the computation of the longitudinal propagation velocity Simulation yields to v = 30 ms in the pole turn and 3 ms are needed to reach 100 mV for an INZ of 3 cm length

Rdu

mp =

15 m

ΩCold diode

Uthr=6V Rdiff=01 microΩ

L = 159 HQuenching magnet

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

18Susana Izquierdo Bermudez

Que

nch

initi

atio

n

Que

nch

dete

ctio

n

Valid

atio

n an

d po

wer

su

pply

off

Que

nch

heat

er

effe

ctiv

e

Que

nch

heat

er

prov

oked

qu

ench

t=0 t=3 ms t=13 ms t=18 ms t=31 ms

25 MA2sMIITs 18 MA2s 131 MA2s

4 Quench performance under accelerator conditions (II)

450

0

TOTAL MIITs = 174 MA2s

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

19Susana Izquierdo Bermudez

5 Final Remarksbull The model is a mix of optimistic and pessimistic assumptions

bull PESSIMISTICbull There is no cooling in the coil except through the heaters once the heater temperature

is lower than the coil temperaturebull OPTIMISTIC

bull The detection threshold is 01 V with 10 ms validation delaybull Delay between quench detection and heater firing is 5 ms (actual value in LHC RB

circuits up to 50 ms)bull ROXIE thermal network has limitations that we try to overcome via fitting

factorsbull More detailed quench heaters model show better agreement with experimental

results without any free parameters [Tiina Salmi]bull Inter-layer quench propagation computed in ROXIE is much slower than

experimental resultsbull Adaptive mesh tracking is a must for efficient quench simulation [Luca Bottura

MT23]bull CERN uses mica-glass insulation (lower thermal conductivity than G10)

bull REF Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator Magnets Andries den Ouden and Herman HJ ten Kate

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

20Susana Izquierdo Bermudez

6 Baseline designbull Only outer layer heaters not potted with the coilbull Copper cladded heating stations 50 mm coverage 90 mm in between

heater stations for the low field region and 130 mm for the high fieldbull Heater to coil insulation = 50 microm kapton + 125 microm G10 bull Voltage tap location

x x x

x x x

x x xx x x

x

x

xNb3Sn-NbTi

x x x

x x x

x x xx x x

xxx

xxx

xLayer jump

xNb3Sn-NbTi

Outer Layer Inner Layer

(full monitoring of the mid-plane and pole turns)

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

21Susana Izquierdo Bermudez

7 ConclusionsFuture workbull The low CuSC ratio combined with the larger temperature margins

make the protection of the 11T dipole a non-trivial problembull Efficient heat transfer from quench heaters to coil is a must

bull Minimize insulation thickness assuring electrical integritybull High power density and coverage require high currents andor big

number of heating firing unitsbull Efficient configuration in terms of heating stations

bull Inter-layer heaters are an interesting bull Lower margin in the inner layer faster heater provoked quenchbull More uniform heat propagation within the coilbull Simplify the requirement of having a redundant system

bull Could AC losses trigger a quench (discharge of capacitance) How would it impact the rest of the RB circuit

bull Quench-back modeling needs to be improved

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

22Susana Izquierdo Bermudez

Referencesbull Quench heater experiments on the lhc main superconducting magnets F Rodriguez-Mateos P

PugnatS Sanfilippo R Schmidt A Siemko F Sonnemannbull LQ Protection Heater Test at Liquid Nitrogen Temperature G Chlachidze G Ambrosio H Felice1 F

Lewis FNobrega D Orris TD-09-007bull Experimental Results and Analysis from the 11T Nb3Sn DS Dipole G Chlachidze I Novitski AV Zlobin

(Fermilab) B Auchmann M Karppinen (CERN)bull EDMS1257407 11-T protection studies at CERN B Auchmannbull Challenges in the Thermal Modeling of Quenches with ROXIE Nikolai Schwerg Bernhard Auchmann

and Stephan Russenschuckbull Quench Simulation in an Integrated Design Environment for Superconducting Magnets Nikolai

Schwerg Bernhard Auchmann and Stephan Russenschuckbull Numerical Calculation of Transient Field Effects in Quenching Superconducting Magnets PhD Thesis

Juljan Nikolai Schwergbull Thermal Conductivity of Micaglass Insulation for Impregnated Nb3Sn Windings in Accelerator

Magnets Andries den Ouden and Herman HJ ten Katebull Electrodynamics of superconducting cables in accelerator magnets Arjan Peter Verweijbull Rossi L et al MATPRO a computer library of material property at cryogenic temperature Tech

Report INFN 2006bull httpte-epc-lpcwebcernchte-epc-lpcconvertersqhpsgeneralstm

Additional slides

24Susana Izquierdo Bermudez

Impact of copper RRR

RRRtotal MITTS

Peak temperature (K)

Δ MITTS ()

ΔTmax ()

50 156 378 -69 -23

100 171 397 00 00

150 177 406 27 12

200 181 412 43 22

0 005 01 015 02 0250

5

10

15

20

time (ms)

MIIT

s

RRR=50RRR=100RRR=150RRR=200

0 5 10 150

100

200

300

400

MIITs [MA2s]P

eat T

empe

ratu

re [K

]

RRR=50RRR=100RRR=150RRR=200

when RRR when RRR (for a fixed Tmax)

25Susana Izquierdo Bermudez

MB vs 11TParameter MB 11T

Magnet

MIITs to reach 400 K 8T MA2s 52 18

Temperature margin LF 4 8-9

Temperature margin HF 3-4 5-9

Differential Inductance mHm 69 117

Stored energy kJm 567 897

Quench heater

circuit

Operational voltage V 450 450

Peak Current A 85 110-120

Maximum stored energy kJ 286 25 - 35

Time constant ms 75 55-72

Quench Heater Pattern 400 mm plated120 mm un-plated

90-140 mm plated50 mm un-plated

26Susana Izquierdo Bermudez

Cable Parameters

Parameter Value Cable width mm 14847 Cable mid thickness mm 1307 Strand diameter mm 07 No of strands 40 CuSc ratio 1106 Insulation thicknessmm 01 Total cable area mm2 22676 Total strand area mm2 15394 Cu area mm2 8084 SC area Nb3Sn mm2 7310 Insulation area G10 mm2 3271 Void area filled with epoxy mm2 4011 Cu RRR 100

27Susana Izquierdo Bermudez

Impact of conductor coverage

Δ Heater Delay () for a

constant QH power densityCASE 1 adjacent conductors covered by QH 0CASE 2 only one of the adjacent conductors covered by QH + 18CASE 2 none of the adjacent conductors covered by QH + 36

Pole turn

5556 54 53 52

Simulated turn to turn propagation time 3 ms in the pole turn 22 ms in the outer layer mid-plane

Increase in QH delay in conductor 53

Case 1 adjacent conductors covered by QH

Case 2 only one of the adjacent conductors is covered by QH

QH case 1

QH case 2

QH case 3

Case 3 none of the adjacent conductors is covered by QH

28Susana Izquierdo Bermudez

Protection System LHC Magnets

The Protection System for the Superconducting Elements of the Large Hadron Collider at CERNK Dahlerup-Petersen1 R Denz1 JL Gomez-Costa1 D Hagedorn1 P Proudlock1 F Rodriguez-Mateos1 R Schmidt1 and F Sonnemann2

29Susana Izquierdo Bermudez

STANDARD LHC HEATER POWER SUPPLIESbull Supply based on the thyristor-triggered discharge of aluminium electrolytic capacitorsbull Each power supply contains a bank with 6 capacitors (47 mF500V) where two sets of 3

parallel capacitors are connected in series total capacitance 705 mF

bull Nominal operating voltage 450 V (90 of the maximum voltage)bull OPERATION Peak current about 85 A giving a maximum stored energy of 286 kJ

Actual limitations in terms of current bull Power supply equipped with two SKT8018E type thyristors rated for 80 A at 85 ˚C bull Maximum current for continuous operation = 135 Abull Peak current at 25 ˚C for 10 ms =1700 A (it will probably destroy the PCB of the power supply)bull Can be safely operated up to 300 A (resistive load in LHC from 12Ω in most of the circuits to

31 Ω in some systems such as D1 protection )

QUENCH HEATER EXPERIMENTS ON THE LHC MAIN SUPERCONDUCTING MAGNETSF Rodriguez-Mateos P PugnatS Sanfilippo R Schmidt A Siemko F Sonnemann

30Susana Izquierdo Bermudez

Impact of insulation materialthicknesskapton

thicknessG10

thicknessOL HF heater

delay (ms) ∆ OL HF heater

delay (ms) ∆ OL HF heater

delay ()0075 0 11 0 000075 02 135 25 2270275 0 26 15 1364

Kapton G10

Ther

mal

con

duct

ivity

Hea

t cap

acity

httpsespacecernchroxieDocumentationMaterialspdf

31Susana Izquierdo Bermudez

Impact of insulation materialthickness

0 5 10 15 200

05

1

15

2

25x 10-5

T (K)

Ther

mal

diff

usiv

ity (m

2 s)

Thermal diffusivity

KaptonG10

32Susana Izquierdo Bermudez

ROXIE Thermal Network

TbathGij

Theater2bath

GijTheater2coil

GijTheater2coil

Lumped thermal network model in comparison to the coilconductor geometry

33Susana Izquierdo Bermudez

Tmax vs MIITsExperimental Results and Analysis from the 11T Nb3Sn DS Dipole

0 5 10 15 20 250

100

200

300

400

Av_1122-0

Av_2-0

Quench Integral (106 A2s)Tm

ax (K

)

ldquoTo keep the cable temperature during a quench below 400 K the quench integral has to be less than 19-21 MIITsldquo

G Chlachidze I Novitski AV Zlobin (Fermilab)B Auchmann M Karppinen (CERN)

• Magnet protection studies and heater design
• OUTLINE
• 1 Margin and MIITs overview
• Longitudinal quench propagation
• Slide 5
• 2Quench study based on FNAL 11T tests QI study
• Slide 7
• Slide 8
• 3 Minimize heaters delay inter-layer heaters
• 3 Minimize heaters delay reduce kapton thickness
• 3 Minimize heaters delay heater design optimization
• 3 Minimize heaters delay heater design optimization (2)
• 3 Minimize heaters delay heater design optimization (3)
• 3 Minimize heaters delay heater design optimization (4)
• 3 Minimize heaters delay heater design optimization (5)
• Slide 16
• 4 Quench performance under accelerator conditions (I)
• Slide 18
• 5 Final Remarks
• 6 Baseline design
• 7 ConclusionsFuture work
• References
• Additional slides
• Impact of copper RRR
• MB vs 11T
• Cable Parameters
• Impact of conductor coverage
• Protection System LHC Magnets
• STANDARD LHC HEATER POWER SUPPLIES
• Impact of insulation materialthickness
• Impact of insulation materialthickness (2)
• ROXIE Thermal Network
• Tmax vs MIITs

24Susana Izquierdo Bermudez

Impact of copper RRR

RRRtotal MITTS

Peak temperature (K)

Δ MITTS ()

ΔTmax ()

50 156 378 -69 -23

100 171 397 00 00

150 177 406 27 12

200 181 412 43 22

0 005 01 015 02 0250

5

10

15

20

time (ms)

MIIT

s

RRR=50RRR=100RRR=150RRR=200

0 5 10 150

100

200

300

400

MIITs [MA2s]P

eat T

empe

ratu

re [K

]

RRR=50RRR=100RRR=150RRR=200

when RRR when RRR (for a fixed Tmax)

25Susana Izquierdo Bermudez

MB vs 11TParameter MB 11T

Magnet

MIITs to reach 400 K 8T MA2s 52 18

Temperature margin LF 4 8-9

Temperature margin HF 3-4 5-9

Differential Inductance mHm 69 117

Stored energy kJm 567 897

Quench heater

circuit

Operational voltage V 450 450

Peak Current A 85 110-120

Maximum stored energy kJ 286 25 - 35

Time constant ms 75 55-72

Quench Heater Pattern 400 mm plated120 mm un-plated

90-140 mm plated50 mm un-plated

26Susana Izquierdo Bermudez

Cable Parameters

Parameter Value Cable width mm 14847 Cable mid thickness mm 1307 Strand diameter mm 07 No of strands 40 CuSc ratio 1106 Insulation thicknessmm 01 Total cable area mm2 22676 Total strand area mm2 15394 Cu area mm2 8084 SC area Nb3Sn mm2 7310 Insulation area G10 mm2 3271 Void area filled with epoxy mm2 4011 Cu RRR 100

27Susana Izquierdo Bermudez

Impact of conductor coverage

Δ Heater Delay () for a

constant QH power densityCASE 1 adjacent conductors covered by QH 0CASE 2 only one of the adjacent conductors covered by QH + 18CASE 2 none of the adjacent conductors covered by QH + 36

Pole turn

5556 54 53 52

Simulated turn to turn propagation time 3 ms in the pole turn 22 ms in the outer layer mid-plane

Increase in QH delay in conductor 53

Case 1 adjacent conductors covered by QH

Case 2 only one of the adjacent conductors is covered by QH

QH case 1

QH case 2

QH case 3

Case 3 none of the adjacent conductors is covered by QH

28Susana Izquierdo Bermudez

Protection System LHC Magnets

The Protection System for the Superconducting Elements of the Large Hadron Collider at CERNK Dahlerup-Petersen1 R Denz1 JL Gomez-Costa1 D Hagedorn1 P Proudlock1 F Rodriguez-Mateos1 R Schmidt1 and F Sonnemann2

29Susana Izquierdo Bermudez

STANDARD LHC HEATER POWER SUPPLIESbull Supply based on the thyristor-triggered discharge of aluminium electrolytic capacitorsbull Each power supply contains a bank with 6 capacitors (47 mF500V) where two sets of 3

parallel capacitors are connected in series total capacitance 705 mF

bull Nominal operating voltage 450 V (90 of the maximum voltage)bull OPERATION Peak current about 85 A giving a maximum stored energy of 286 kJ

Actual limitations in terms of current bull Power supply equipped with two SKT8018E type thyristors rated for 80 A at 85 ˚C bull Maximum current for continuous operation = 135 Abull Peak current at 25 ˚C for 10 ms =1700 A (it will probably destroy the PCB of the power supply)bull Can be safely operated up to 300 A (resistive load in LHC from 12Ω in most of the circuits to

31 Ω in some systems such as D1 protection )

QUENCH HEATER EXPERIMENTS ON THE LHC MAIN SUPERCONDUCTING MAGNETSF Rodriguez-Mateos P PugnatS Sanfilippo R Schmidt A Siemko F Sonnemann

30Susana Izquierdo Bermudez

Impact of insulation materialthicknesskapton

thicknessG10

thicknessOL HF heater

delay (ms) ∆ OL HF heater

delay (ms) ∆ OL HF heater

delay ()0075 0 11 0 000075 02 135 25 2270275 0 26 15 1364

Kapton G10

Ther

mal

con

duct

ivity

Hea

t cap

acity

httpsespacecernchroxieDocumentationMaterialspdf

31Susana Izquierdo Bermudez

Impact of insulation materialthickness

0 5 10 15 200

05

1

15

2

25x 10-5

T (K)

Ther

mal

diff

usiv

ity (m

2 s)

Thermal diffusivity

KaptonG10

32Susana Izquierdo Bermudez

ROXIE Thermal Network

TbathGij

Theater2bath

GijTheater2coil

GijTheater2coil

Lumped thermal network model in comparison to the coilconductor geometry

33Susana Izquierdo Bermudez

Tmax vs MIITsExperimental Results and Analysis from the 11T Nb3Sn DS Dipole

0 5 10 15 20 250

100

200

300

400

Av_1122-0

Av_2-0

Quench Integral (106 A2s)Tm

ax (K

)

ldquoTo keep the cable temperature during a quench below 400 K the quench integral has to be less than 19-21 MIITsldquo

G Chlachidze I Novitski AV Zlobin (Fermilab)B Auchmann M Karppinen (CERN)

• Magnet protection studies and heater design
• OUTLINE
• 1 Margin and MIITs overview
• Longitudinal quench propagation
• Slide 5
• 2Quench study based on FNAL 11T tests QI study
• Slide 7
• Slide 8
• 3 Minimize heaters delay inter-layer heaters
• 3 Minimize heaters delay reduce kapton thickness
• 3 Minimize heaters delay heater design optimization
• 3 Minimize heaters delay heater design optimization (2)
• 3 Minimize heaters delay heater design optimization (3)
• 3 Minimize heaters delay heater design optimization (4)
• 3 Minimize heaters delay heater design optimization (5)
• Slide 16
• 4 Quench performance under accelerator conditions (I)
• Slide 18
• 5 Final Remarks
• 6 Baseline design
• 7 ConclusionsFuture work
• References
• Additional slides
• Impact of copper RRR
• MB vs 11T
• Cable Parameters
• Impact of conductor coverage
• Protection System LHC Magnets
• STANDARD LHC HEATER POWER SUPPLIES
• Impact of insulation materialthickness
• Impact of insulation materialthickness (2)
• ROXIE Thermal Network
• Tmax vs MIITs

25Susana Izquierdo Bermudez

MB vs 11TParameter MB 11T

Magnet

MIITs to reach 400 K 8T MA2s 52 18

Temperature margin LF 4 8-9

Temperature margin HF 3-4 5-9

Differential Inductance mHm 69 117

Stored energy kJm 567 897

Quench heater

circuit

Operational voltage V 450 450

Peak Current A 85 110-120

Maximum stored energy kJ 286 25 - 35

Time constant ms 75 55-72

Quench Heater Pattern 400 mm plated120 mm un-plated

90-140 mm plated50 mm un-plated

26Susana Izquierdo Bermudez

Cable Parameters

Parameter Value Cable width mm 14847 Cable mid thickness mm 1307 Strand diameter mm 07 No of strands 40 CuSc ratio 1106 Insulation thicknessmm 01 Total cable area mm2 22676 Total strand area mm2 15394 Cu area mm2 8084 SC area Nb3Sn mm2 7310 Insulation area G10 mm2 3271 Void area filled with epoxy mm2 4011 Cu RRR 100

27Susana Izquierdo Bermudez

Impact of conductor coverage

Δ Heater Delay () for a

constant QH power densityCASE 1 adjacent conductors covered by QH 0CASE 2 only one of the adjacent conductors covered by QH + 18CASE 2 none of the adjacent conductors covered by QH + 36

Pole turn

5556 54 53 52

Simulated turn to turn propagation time 3 ms in the pole turn 22 ms in the outer layer mid-plane

Increase in QH delay in conductor 53

Case 1 adjacent conductors covered by QH

Case 2 only one of the adjacent conductors is covered by QH

QH case 1

QH case 2

QH case 3

Case 3 none of the adjacent conductors is covered by QH

28Susana Izquierdo Bermudez

Protection System LHC Magnets

The Protection System for the Superconducting Elements of the Large Hadron Collider at CERNK Dahlerup-Petersen1 R Denz1 JL Gomez-Costa1 D Hagedorn1 P Proudlock1 F Rodriguez-Mateos1 R Schmidt1 and F Sonnemann2

29Susana Izquierdo Bermudez

STANDARD LHC HEATER POWER SUPPLIESbull Supply based on the thyristor-triggered discharge of aluminium electrolytic capacitorsbull Each power supply contains a bank with 6 capacitors (47 mF500V) where two sets of 3

parallel capacitors are connected in series total capacitance 705 mF

bull Nominal operating voltage 450 V (90 of the maximum voltage)bull OPERATION Peak current about 85 A giving a maximum stored energy of 286 kJ

Actual limitations in terms of current bull Power supply equipped with two SKT8018E type thyristors rated for 80 A at 85 ˚C bull Maximum current for continuous operation = 135 Abull Peak current at 25 ˚C for 10 ms =1700 A (it will probably destroy the PCB of the power supply)bull Can be safely operated up to 300 A (resistive load in LHC from 12Ω in most of the circuits to

31 Ω in some systems such as D1 protection )

QUENCH HEATER EXPERIMENTS ON THE LHC MAIN SUPERCONDUCTING MAGNETSF Rodriguez-Mateos P PugnatS Sanfilippo R Schmidt A Siemko F Sonnemann

30Susana Izquierdo Bermudez

Impact of insulation materialthicknesskapton

thicknessG10

thicknessOL HF heater

delay (ms) ∆ OL HF heater

delay (ms) ∆ OL HF heater

delay ()0075 0 11 0 000075 02 135 25 2270275 0 26 15 1364

Kapton G10

Ther

mal

con

duct

ivity

Hea

t cap

acity

httpsespacecernchroxieDocumentationMaterialspdf

31Susana Izquierdo Bermudez

Impact of insulation materialthickness

0 5 10 15 200

05

1

15

2

25x 10-5

T (K)

Ther

mal

diff

usiv

ity (m

2 s)

Thermal diffusivity

KaptonG10

32Susana Izquierdo Bermudez

ROXIE Thermal Network

TbathGij

Theater2bath

GijTheater2coil

GijTheater2coil

Lumped thermal network model in comparison to the coilconductor geometry

33Susana Izquierdo Bermudez

Tmax vs MIITsExperimental Results and Analysis from the 11T Nb3Sn DS Dipole

0 5 10 15 20 250

100

200

300

400

Av_1122-0

Av_2-0

Quench Integral (106 A2s)Tm

ax (K

)

ldquoTo keep the cable temperature during a quench below 400 K the quench integral has to be less than 19-21 MIITsldquo

G Chlachidze I Novitski AV Zlobin (Fermilab)B Auchmann M Karppinen (CERN)

• Magnet protection studies and heater design
• OUTLINE
• 1 Margin and MIITs overview
• Longitudinal quench propagation
• Slide 5
• 2Quench study based on FNAL 11T tests QI study
• Slide 7
• Slide 8
• 3 Minimize heaters delay inter-layer heaters
• 3 Minimize heaters delay reduce kapton thickness
• 3 Minimize heaters delay heater design optimization
• 3 Minimize heaters delay heater design optimization (2)
• 3 Minimize heaters delay heater design optimization (3)
• 3 Minimize heaters delay heater design optimization (4)
• 3 Minimize heaters delay heater design optimization (5)
• Slide 16
• 4 Quench performance under accelerator conditions (I)
• Slide 18
• 5 Final Remarks
• 6 Baseline design
• 7 ConclusionsFuture work
• References
• Additional slides
• Impact of copper RRR
• MB vs 11T
• Cable Parameters
• Impact of conductor coverage
• Protection System LHC Magnets
• STANDARD LHC HEATER POWER SUPPLIES
• Impact of insulation materialthickness
• Impact of insulation materialthickness (2)
• ROXIE Thermal Network
• Tmax vs MIITs

26Susana Izquierdo Bermudez

Cable Parameters

Parameter Value Cable width mm 14847 Cable mid thickness mm 1307 Strand diameter mm 07 No of strands 40 CuSc ratio 1106 Insulation thicknessmm 01 Total cable area mm2 22676 Total strand area mm2 15394 Cu area mm2 8084 SC area Nb3Sn mm2 7310 Insulation area G10 mm2 3271 Void area filled with epoxy mm2 4011 Cu RRR 100

27Susana Izquierdo Bermudez

Impact of conductor coverage

Δ Heater Delay () for a

constant QH power densityCASE 1 adjacent conductors covered by QH 0CASE 2 only one of the adjacent conductors covered by QH + 18CASE 2 none of the adjacent conductors covered by QH + 36

Pole turn

5556 54 53 52

Simulated turn to turn propagation time 3 ms in the pole turn 22 ms in the outer layer mid-plane

Increase in QH delay in conductor 53

Case 1 adjacent conductors covered by QH

Case 2 only one of the adjacent conductors is covered by QH

QH case 1

QH case 2

QH case 3

Case 3 none of the adjacent conductors is covered by QH

28Susana Izquierdo Bermudez

Protection System LHC Magnets

The Protection System for the Superconducting Elements of the Large Hadron Collider at CERNK Dahlerup-Petersen1 R Denz1 JL Gomez-Costa1 D Hagedorn1 P Proudlock1 F Rodriguez-Mateos1 R Schmidt1 and F Sonnemann2

29Susana Izquierdo Bermudez

STANDARD LHC HEATER POWER SUPPLIESbull Supply based on the thyristor-triggered discharge of aluminium electrolytic capacitorsbull Each power supply contains a bank with 6 capacitors (47 mF500V) where two sets of 3

parallel capacitors are connected in series total capacitance 705 mF

bull Nominal operating voltage 450 V (90 of the maximum voltage)bull OPERATION Peak current about 85 A giving a maximum stored energy of 286 kJ

Actual limitations in terms of current bull Power supply equipped with two SKT8018E type thyristors rated for 80 A at 85 ˚C bull Maximum current for continuous operation = 135 Abull Peak current at 25 ˚C for 10 ms =1700 A (it will probably destroy the PCB of the power supply)bull Can be safely operated up to 300 A (resistive load in LHC from 12Ω in most of the circuits to

31 Ω in some systems such as D1 protection )

QUENCH HEATER EXPERIMENTS ON THE LHC MAIN SUPERCONDUCTING MAGNETSF Rodriguez-Mateos P PugnatS Sanfilippo R Schmidt A Siemko F Sonnemann

30Susana Izquierdo Bermudez

Impact of insulation materialthicknesskapton

thicknessG10

thicknessOL HF heater

delay (ms) ∆ OL HF heater

delay (ms) ∆ OL HF heater

delay ()0075 0 11 0 000075 02 135 25 2270275 0 26 15 1364

Kapton G10

Ther

mal

con

duct

ivity

Hea

t cap

acity

httpsespacecernchroxieDocumentationMaterialspdf

31Susana Izquierdo Bermudez

Impact of insulation materialthickness

0 5 10 15 200

05

1

15

2

25x 10-5

T (K)

Ther

mal

diff

usiv

ity (m

2 s)

Thermal diffusivity

KaptonG10

32Susana Izquierdo Bermudez

ROXIE Thermal Network

TbathGij

Theater2bath

GijTheater2coil

GijTheater2coil

Lumped thermal network model in comparison to the coilconductor geometry

33Susana Izquierdo Bermudez

Tmax vs MIITsExperimental Results and Analysis from the 11T Nb3Sn DS Dipole

0 5 10 15 20 250

100

200

300

400

Av_1122-0

Av_2-0

Quench Integral (106 A2s)Tm

ax (K

)

ldquoTo keep the cable temperature during a quench below 400 K the quench integral has to be less than 19-21 MIITsldquo

G Chlachidze I Novitski AV Zlobin (Fermilab)B Auchmann M Karppinen (CERN)

• Magnet protection studies and heater design
• OUTLINE
• 1 Margin and MIITs overview
• Longitudinal quench propagation
• Slide 5
• 2Quench study based on FNAL 11T tests QI study
• Slide 7
• Slide 8
• 3 Minimize heaters delay inter-layer heaters
• 3 Minimize heaters delay reduce kapton thickness
• 3 Minimize heaters delay heater design optimization
• 3 Minimize heaters delay heater design optimization (2)
• 3 Minimize heaters delay heater design optimization (3)
• 3 Minimize heaters delay heater design optimization (4)
• 3 Minimize heaters delay heater design optimization (5)
• Slide 16
• 4 Quench performance under accelerator conditions (I)
• Slide 18
• 5 Final Remarks
• 6 Baseline design
• 7 ConclusionsFuture work
• References
• Additional slides
• Impact of copper RRR
• MB vs 11T
• Cable Parameters
• Impact of conductor coverage
• Protection System LHC Magnets
• STANDARD LHC HEATER POWER SUPPLIES
• Impact of insulation materialthickness
• Impact of insulation materialthickness (2)
• ROXIE Thermal Network
• Tmax vs MIITs

27Susana Izquierdo Bermudez

Impact of conductor coverage

Δ Heater Delay () for a

constant QH power densityCASE 1 adjacent conductors covered by QH 0CASE 2 only one of the adjacent conductors covered by QH + 18CASE 2 none of the adjacent conductors covered by QH + 36

Pole turn

5556 54 53 52

Simulated turn to turn propagation time 3 ms in the pole turn 22 ms in the outer layer mid-plane

Increase in QH delay in conductor 53

Case 1 adjacent conductors covered by QH

Case 2 only one of the adjacent conductors is covered by QH

QH case 1

QH case 2

QH case 3

Case 3 none of the adjacent conductors is covered by QH

28Susana Izquierdo Bermudez

Protection System LHC Magnets

The Protection System for the Superconducting Elements of the Large Hadron Collider at CERNK Dahlerup-Petersen1 R Denz1 JL Gomez-Costa1 D Hagedorn1 P Proudlock1 F Rodriguez-Mateos1 R Schmidt1 and F Sonnemann2

29Susana Izquierdo Bermudez

STANDARD LHC HEATER POWER SUPPLIESbull Supply based on the thyristor-triggered discharge of aluminium electrolytic capacitorsbull Each power supply contains a bank with 6 capacitors (47 mF500V) where two sets of 3

parallel capacitors are connected in series total capacitance 705 mF

bull Nominal operating voltage 450 V (90 of the maximum voltage)bull OPERATION Peak current about 85 A giving a maximum stored energy of 286 kJ

Actual limitations in terms of current bull Power supply equipped with two SKT8018E type thyristors rated for 80 A at 85 ˚C bull Maximum current for continuous operation = 135 Abull Peak current at 25 ˚C for 10 ms =1700 A (it will probably destroy the PCB of the power supply)bull Can be safely operated up to 300 A (resistive load in LHC from 12Ω in most of the circuits to

31 Ω in some systems such as D1 protection )

QUENCH HEATER EXPERIMENTS ON THE LHC MAIN SUPERCONDUCTING MAGNETSF Rodriguez-Mateos P PugnatS Sanfilippo R Schmidt A Siemko F Sonnemann

30Susana Izquierdo Bermudez

Impact of insulation materialthicknesskapton

thicknessG10

thicknessOL HF heater

delay (ms) ∆ OL HF heater

delay (ms) ∆ OL HF heater

delay ()0075 0 11 0 000075 02 135 25 2270275 0 26 15 1364

Kapton G10

Ther

mal

con

duct

ivity

Hea

t cap

acity

httpsespacecernchroxieDocumentationMaterialspdf

31Susana Izquierdo Bermudez

Impact of insulation materialthickness

0 5 10 15 200

05

1

15

2

25x 10-5

T (K)

Ther

mal

diff

usiv

ity (m

2 s)

Thermal diffusivity

KaptonG10

32Susana Izquierdo Bermudez

ROXIE Thermal Network

TbathGij

Theater2bath

GijTheater2coil

GijTheater2coil

Lumped thermal network model in comparison to the coilconductor geometry

33Susana Izquierdo Bermudez

Tmax vs MIITsExperimental Results and Analysis from the 11T Nb3Sn DS Dipole

0 5 10 15 20 250

100

200

300

400

Av_1122-0

Av_2-0

Quench Integral (106 A2s)Tm

ax (K

)

ldquoTo keep the cable temperature during a quench below 400 K the quench integral has to be less than 19-21 MIITsldquo

G Chlachidze I Novitski AV Zlobin (Fermilab)B Auchmann M Karppinen (CERN)

• Magnet protection studies and heater design
• OUTLINE
• 1 Margin and MIITs overview
• Longitudinal quench propagation
• Slide 5
• 2Quench study based on FNAL 11T tests QI study
• Slide 7
• Slide 8
• 3 Minimize heaters delay inter-layer heaters
• 3 Minimize heaters delay reduce kapton thickness
• 3 Minimize heaters delay heater design optimization
• 3 Minimize heaters delay heater design optimization (2)
• 3 Minimize heaters delay heater design optimization (3)
• 3 Minimize heaters delay heater design optimization (4)
• 3 Minimize heaters delay heater design optimization (5)
• Slide 16
• 4 Quench performance under accelerator conditions (I)
• Slide 18
• 5 Final Remarks
• 6 Baseline design
• 7 ConclusionsFuture work
• References
• Additional slides
• Impact of copper RRR
• MB vs 11T
• Cable Parameters
• Impact of conductor coverage
• Protection System LHC Magnets
• STANDARD LHC HEATER POWER SUPPLIES
• Impact of insulation materialthickness
• Impact of insulation materialthickness (2)
• ROXIE Thermal Network
• Tmax vs MIITs

28Susana Izquierdo Bermudez

Protection System LHC Magnets

The Protection System for the Superconducting Elements of the Large Hadron Collider at CERNK Dahlerup-Petersen1 R Denz1 JL Gomez-Costa1 D Hagedorn1 P Proudlock1 F Rodriguez-Mateos1 R Schmidt1 and F Sonnemann2

29Susana Izquierdo Bermudez

STANDARD LHC HEATER POWER SUPPLIESbull Supply based on the thyristor-triggered discharge of aluminium electrolytic capacitorsbull Each power supply contains a bank with 6 capacitors (47 mF500V) where two sets of 3

parallel capacitors are connected in series total capacitance 705 mF

bull Nominal operating voltage 450 V (90 of the maximum voltage)bull OPERATION Peak current about 85 A giving a maximum stored energy of 286 kJ

Actual limitations in terms of current bull Power supply equipped with two SKT8018E type thyristors rated for 80 A at 85 ˚C bull Maximum current for continuous operation = 135 Abull Peak current at 25 ˚C for 10 ms =1700 A (it will probably destroy the PCB of the power supply)bull Can be safely operated up to 300 A (resistive load in LHC from 12Ω in most of the circuits to

31 Ω in some systems such as D1 protection )

QUENCH HEATER EXPERIMENTS ON THE LHC MAIN SUPERCONDUCTING MAGNETSF Rodriguez-Mateos P PugnatS Sanfilippo R Schmidt A Siemko F Sonnemann

30Susana Izquierdo Bermudez

Impact of insulation materialthicknesskapton

thicknessG10

thicknessOL HF heater

delay (ms) ∆ OL HF heater

delay (ms) ∆ OL HF heater

delay ()0075 0 11 0 000075 02 135 25 2270275 0 26 15 1364

Kapton G10

Ther

mal

con

duct

ivity

Hea

t cap

acity

httpsespacecernchroxieDocumentationMaterialspdf

31Susana Izquierdo Bermudez

Impact of insulation materialthickness

0 5 10 15 200

05

1

15

2

25x 10-5

T (K)

Ther

mal

diff

usiv

ity (m

2 s)

Thermal diffusivity

KaptonG10

32Susana Izquierdo Bermudez

ROXIE Thermal Network

TbathGij

Theater2bath

GijTheater2coil

GijTheater2coil

Lumped thermal network model in comparison to the coilconductor geometry

33Susana Izquierdo Bermudez

Tmax vs MIITsExperimental Results and Analysis from the 11T Nb3Sn DS Dipole

0 5 10 15 20 250

100

200

300

400

Av_1122-0

Av_2-0

Quench Integral (106 A2s)Tm

ax (K

)

ldquoTo keep the cable temperature during a quench below 400 K the quench integral has to be less than 19-21 MIITsldquo

G Chlachidze I Novitski AV Zlobin (Fermilab)B Auchmann M Karppinen (CERN)

• Magnet protection studies and heater design
• OUTLINE
• 1 Margin and MIITs overview
• Longitudinal quench propagation
• Slide 5
• 2Quench study based on FNAL 11T tests QI study
• Slide 7
• Slide 8
• 3 Minimize heaters delay inter-layer heaters
• 3 Minimize heaters delay reduce kapton thickness
• 3 Minimize heaters delay heater design optimization
• 3 Minimize heaters delay heater design optimization (2)
• 3 Minimize heaters delay heater design optimization (3)
• 3 Minimize heaters delay heater design optimization (4)
• 3 Minimize heaters delay heater design optimization (5)
• Slide 16
• 4 Quench performance under accelerator conditions (I)
• Slide 18
• 5 Final Remarks
• 6 Baseline design
• 7 ConclusionsFuture work
• References
• Additional slides
• Impact of copper RRR
• MB vs 11T
• Cable Parameters
• Impact of conductor coverage
• Protection System LHC Magnets
• STANDARD LHC HEATER POWER SUPPLIES
• Impact of insulation materialthickness
• Impact of insulation materialthickness (2)
• ROXIE Thermal Network
• Tmax vs MIITs

29Susana Izquierdo Bermudez

STANDARD LHC HEATER POWER SUPPLIESbull Supply based on the thyristor-triggered discharge of aluminium electrolytic capacitorsbull Each power supply contains a bank with 6 capacitors (47 mF500V) where two sets of 3

parallel capacitors are connected in series total capacitance 705 mF

bull Nominal operating voltage 450 V (90 of the maximum voltage)bull OPERATION Peak current about 85 A giving a maximum stored energy of 286 kJ

Actual limitations in terms of current bull Power supply equipped with two SKT8018E type thyristors rated for 80 A at 85 ˚C bull Maximum current for continuous operation = 135 Abull Peak current at 25 ˚C for 10 ms =1700 A (it will probably destroy the PCB of the power supply)bull Can be safely operated up to 300 A (resistive load in LHC from 12Ω in most of the circuits to

31 Ω in some systems such as D1 protection )

QUENCH HEATER EXPERIMENTS ON THE LHC MAIN SUPERCONDUCTING MAGNETSF Rodriguez-Mateos P PugnatS Sanfilippo R Schmidt A Siemko F Sonnemann

30Susana Izquierdo Bermudez

Impact of insulation materialthicknesskapton

thicknessG10

thicknessOL HF heater

delay (ms) ∆ OL HF heater

delay (ms) ∆ OL HF heater

delay ()0075 0 11 0 000075 02 135 25 2270275 0 26 15 1364

Kapton G10

Ther

mal

con

duct

ivity

Hea

t cap

acity

httpsespacecernchroxieDocumentationMaterialspdf

31Susana Izquierdo Bermudez

Impact of insulation materialthickness

0 5 10 15 200

05

1

15

2

25x 10-5

T (K)

Ther

mal

diff

usiv

ity (m

2 s)

Thermal diffusivity

KaptonG10

32Susana Izquierdo Bermudez

ROXIE Thermal Network

TbathGij

Theater2bath

GijTheater2coil

GijTheater2coil

Lumped thermal network model in comparison to the coilconductor geometry

33Susana Izquierdo Bermudez

Tmax vs MIITsExperimental Results and Analysis from the 11T Nb3Sn DS Dipole

0 5 10 15 20 250

100

200

300

400

Av_1122-0

Av_2-0

Quench Integral (106 A2s)Tm

ax (K

)

ldquoTo keep the cable temperature during a quench below 400 K the quench integral has to be less than 19-21 MIITsldquo

G Chlachidze I Novitski AV Zlobin (Fermilab)B Auchmann M Karppinen (CERN)

• Magnet protection studies and heater design
• OUTLINE
• 1 Margin and MIITs overview
• Longitudinal quench propagation
• Slide 5
• 2Quench study based on FNAL 11T tests QI study
• Slide 7
• Slide 8
• 3 Minimize heaters delay inter-layer heaters
• 3 Minimize heaters delay reduce kapton thickness
• 3 Minimize heaters delay heater design optimization
• 3 Minimize heaters delay heater design optimization (2)
• 3 Minimize heaters delay heater design optimization (3)
• 3 Minimize heaters delay heater design optimization (4)
• 3 Minimize heaters delay heater design optimization (5)
• Slide 16
• 4 Quench performance under accelerator conditions (I)
• Slide 18
• 5 Final Remarks
• 6 Baseline design
• 7 ConclusionsFuture work
• References
• Additional slides
• Impact of copper RRR
• MB vs 11T
• Cable Parameters
• Impact of conductor coverage
• Protection System LHC Magnets
• STANDARD LHC HEATER POWER SUPPLIES
• Impact of insulation materialthickness
• Impact of insulation materialthickness (2)
• ROXIE Thermal Network
• Tmax vs MIITs

30Susana Izquierdo Bermudez

Impact of insulation materialthicknesskapton

thicknessG10

thicknessOL HF heater

delay (ms) ∆ OL HF heater

delay (ms) ∆ OL HF heater

delay ()0075 0 11 0 000075 02 135 25 2270275 0 26 15 1364

Kapton G10

Ther

mal

con

duct

ivity

Hea

t cap

acity

httpsespacecernchroxieDocumentationMaterialspdf

31Susana Izquierdo Bermudez

Impact of insulation materialthickness

0 5 10 15 200

05

1

15

2

25x 10-5

T (K)

Ther

mal

diff

usiv

ity (m

2 s)

Thermal diffusivity

KaptonG10

32Susana Izquierdo Bermudez

ROXIE Thermal Network

TbathGij

Theater2bath

GijTheater2coil

GijTheater2coil

Lumped thermal network model in comparison to the coilconductor geometry

33Susana Izquierdo Bermudez

Tmax vs MIITsExperimental Results and Analysis from the 11T Nb3Sn DS Dipole

0 5 10 15 20 250

100

200

300

400

Av_1122-0

Av_2-0

Quench Integral (106 A2s)Tm

ax (K

)

ldquoTo keep the cable temperature during a quench below 400 K the quench integral has to be less than 19-21 MIITsldquo

G Chlachidze I Novitski AV Zlobin (Fermilab)B Auchmann M Karppinen (CERN)

• Magnet protection studies and heater design
• OUTLINE
• 1 Margin and MIITs overview
• Longitudinal quench propagation
• Slide 5
• 2Quench study based on FNAL 11T tests QI study
• Slide 7
• Slide 8
• 3 Minimize heaters delay inter-layer heaters
• 3 Minimize heaters delay reduce kapton thickness
• 3 Minimize heaters delay heater design optimization
• 3 Minimize heaters delay heater design optimization (2)
• 3 Minimize heaters delay heater design optimization (3)
• 3 Minimize heaters delay heater design optimization (4)
• 3 Minimize heaters delay heater design optimization (5)
• Slide 16
• 4 Quench performance under accelerator conditions (I)
• Slide 18
• 5 Final Remarks
• 6 Baseline design
• 7 ConclusionsFuture work
• References
• Additional slides
• Impact of copper RRR
• MB vs 11T
• Cable Parameters
• Impact of conductor coverage
• Protection System LHC Magnets
• STANDARD LHC HEATER POWER SUPPLIES
• Impact of insulation materialthickness
• Impact of insulation materialthickness (2)
• ROXIE Thermal Network
• Tmax vs MIITs

31Susana Izquierdo Bermudez

Impact of insulation materialthickness

0 5 10 15 200

05

1

15

2

25x 10-5

T (K)

Ther

mal

diff

usiv

ity (m

2 s)

Thermal diffusivity

KaptonG10

32Susana Izquierdo Bermudez

ROXIE Thermal Network

TbathGij

Theater2bath

GijTheater2coil

GijTheater2coil

Lumped thermal network model in comparison to the coilconductor geometry

33Susana Izquierdo Bermudez

Tmax vs MIITsExperimental Results and Analysis from the 11T Nb3Sn DS Dipole

0 5 10 15 20 250

100

200

300

400

Av_1122-0

Av_2-0

Quench Integral (106 A2s)Tm

ax (K

)

ldquoTo keep the cable temperature during a quench below 400 K the quench integral has to be less than 19-21 MIITsldquo

G Chlachidze I Novitski AV Zlobin (Fermilab)B Auchmann M Karppinen (CERN)

• Magnet protection studies and heater design
• OUTLINE
• 1 Margin and MIITs overview
• Longitudinal quench propagation
• Slide 5
• 2Quench study based on FNAL 11T tests QI study
• Slide 7
• Slide 8
• 3 Minimize heaters delay inter-layer heaters
• 3 Minimize heaters delay reduce kapton thickness
• 3 Minimize heaters delay heater design optimization
• 3 Minimize heaters delay heater design optimization (2)
• 3 Minimize heaters delay heater design optimization (3)
• 3 Minimize heaters delay heater design optimization (4)
• 3 Minimize heaters delay heater design optimization (5)
• Slide 16
• 4 Quench performance under accelerator conditions (I)
• Slide 18
• 5 Final Remarks
• 6 Baseline design
• 7 ConclusionsFuture work
• References
• Additional slides
• Impact of copper RRR
• MB vs 11T
• Cable Parameters
• Impact of conductor coverage
• Protection System LHC Magnets
• STANDARD LHC HEATER POWER SUPPLIES
• Impact of insulation materialthickness
• Impact of insulation materialthickness (2)
• ROXIE Thermal Network
• Tmax vs MIITs

32Susana Izquierdo Bermudez

ROXIE Thermal Network

TbathGij

Theater2bath

GijTheater2coil

GijTheater2coil

Lumped thermal network model in comparison to the coilconductor geometry

33Susana Izquierdo Bermudez

Tmax vs MIITsExperimental Results and Analysis from the 11T Nb3Sn DS Dipole

0 5 10 15 20 250

100

200

300

400

Av_1122-0

Av_2-0

Quench Integral (106 A2s)Tm

ax (K

)

ldquoTo keep the cable temperature during a quench below 400 K the quench integral has to be less than 19-21 MIITsldquo

G Chlachidze I Novitski AV Zlobin (Fermilab)B Auchmann M Karppinen (CERN)

• Magnet protection studies and heater design
• OUTLINE
• 1 Margin and MIITs overview
• Longitudinal quench propagation
• Slide 5
• 2Quench study based on FNAL 11T tests QI study
• Slide 7
• Slide 8
• 3 Minimize heaters delay inter-layer heaters
• 3 Minimize heaters delay reduce kapton thickness
• 3 Minimize heaters delay heater design optimization
• 3 Minimize heaters delay heater design optimization (2)
• 3 Minimize heaters delay heater design optimization (3)
• 3 Minimize heaters delay heater design optimization (4)
• 3 Minimize heaters delay heater design optimization (5)
• Slide 16
• 4 Quench performance under accelerator conditions (I)
• Slide 18
• 5 Final Remarks
• 6 Baseline design
• 7 ConclusionsFuture work
• References
• Additional slides
• Impact of copper RRR
• MB vs 11T
• Cable Parameters
• Impact of conductor coverage
• Protection System LHC Magnets
• STANDARD LHC HEATER POWER SUPPLIES
• Impact of insulation materialthickness
• Impact of insulation materialthickness (2)
• ROXIE Thermal Network
• Tmax vs MIITs

33Susana Izquierdo Bermudez

Tmax vs MIITsExperimental Results and Analysis from the 11T Nb3Sn DS Dipole

0 5 10 15 20 250

100

200

300

400

Av_1122-0

Av_2-0

Quench Integral (106 A2s)Tm

ax (K

)

ldquoTo keep the cable temperature during a quench below 400 K the quench integral has to be less than 19-21 MIITsldquo

G Chlachidze I Novitski AV Zlobin (Fermilab)B Auchmann M Karppinen (CERN)

• Magnet protection studies and heater design
• OUTLINE
• 1 Margin and MIITs overview
• Longitudinal quench propagation
• Slide 5
• 2Quench study based on FNAL 11T tests QI study
• Slide 7
• Slide 8
• 3 Minimize heaters delay inter-layer heaters
• 3 Minimize heaters delay reduce kapton thickness
• 3 Minimize heaters delay heater design optimization
• 3 Minimize heaters delay heater design optimization (2)
• 3 Minimize heaters delay heater design optimization (3)
• 3 Minimize heaters delay heater design optimization (4)
• 3 Minimize heaters delay heater design optimization (5)
• Slide 16
• 4 Quench performance under accelerator conditions (I)
• Slide 18
• 5 Final Remarks
• 6 Baseline design
• 7 ConclusionsFuture work
• References
• Additional slides
• Impact of copper RRR
• MB vs 11T
• Cable Parameters
• Impact of conductor coverage
• Protection System LHC Magnets
• STANDARD LHC HEATER POWER SUPPLIES
• Impact of insulation materialthickness
• Impact of insulation materialthickness (2)
• ROXIE Thermal Network
• Tmax vs MIITs