11t hybrid assembly 1. disassembly and post mortem analysis … · 2019. 8. 7. · part 1:...

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11T Hybrid Assembly

1. Disassembly and Post Mortem Analysis

2. Revised Project Plan

78th Meeting of the HL-LHC Technical Coordination Committee

T.A. Bampton, M. Bernardini, S.E. Bustamante, A.P. Foussat, O. Housiaux, F. Lackner, M. Michels, J. Petrik, H. Prin, D. Pulikowski, J.L. RudeirosFernandez, F. Savary, D. Schoerling, E. Tsolakis, G. Willering

CERN – Room 30/7-010 – 2019-07-04 – https://indico.cern.ch/event/829607/

https://indico.cern.ch/event/829607/

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Content

Introduction – corrigendum

Part 1: Disassembly and Post Mortem Analysis Quality control plan

Inspection of the cold mass assembly

Inspection of the collared coils / coils (visual, and metrology)

Paschen tests

Thermo-mechanical FEA model

Part 2: Revised Project Plan WUCD process

Revised plan & schedule

F. Savary @ 78th Meeting of the HL-LHC TCC 2

logo

areaF. Savary @ 78th Meeting of the HL-LHC TCC

S0: LMBHP001

Ap1CC01

UpC02

DownC03

Ap2CCR2

UpCR5

DownCR4

Cold Mass Assembly

Collared Coils

CoilsAperture 1 Aperture 2

Hybrid magnet, S0

Schematic view from CS– Corrigendum

3QUICK

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Prototype and Hybrid – Corrigendum

F. Savary @ 78th Meeting of the HL-LHC TCC

LMBHB001

Aperture 1CCR2

UpCR5

DownCR4

Aperture 2CCR3

UpCR7

DownCR6

S0: LMBHP001

Aperture 1CC01

UpC02

DownC03

Aperture 2CCR2

UpCR5

DownCR4

PROTOTYPE – from CS HYBRID – from CS

Tested summer 2018

Outcome of development program

Tested Feb./Mar. 2019

With 1st CC of the series production,

and CCR2 of the prototype as Ap2 4QUICK

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Content





Paschen tests





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QC Steps and description


WBS Step, and description of the QC check

1 After removal of end covers

1.1 Take pictures of CS with focus on leads, and also of NCS

1.2 Record signals of the collar nose strain gauges (CC01 only)

1.3 Check tightening torque of the axial bolts (“bullets”) prior they are unscrewed

2 After removal of the end plates (shells are still welded)

2.1 Take pictures of CS with focus on leads, and also of NCS

2.2 Measure the yoke gap along the assembly with sufficient Nb of points in ends

2.3 Inspect the ends of the coils (visible face of the saddle) on both CS and NCS

2.4

Carry out electrical tests, coil to ground, and coil to QH, only coil C03, and only one QH circuit, as

per assembly conditions prior to cold tests (3.3 kV QH / coil, progressively, in case of breakdown, stop

there)

Carry out other standard electrical tests, inductance, resistance, splices, …6QUICK

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3 After cutting of the shrinking cylinder (at central workshops, bldg. 72)

3.1 Measure the yoke gap along the assembly with sufficient Nr of points in ends, when back in bldg. 180?

4 After return to 180 prior to start further disassembly operations


5 On CC01, once on a bench


5.2

Carry out metrology measurements (outside dimensions of the collars, and length with laser tracker).

Inspect the ends of the collared coils (focus on relative position of the saddle wrt the last collar), on

both CS and NCS

5.3

Depending on the results of the electrical tests carried out at 2.4, repeat them, exact test conditions to

be discussed, only one QH circuit of C03

Carry out other standard electrical tests, inductance, resistance, splices, …

7QUICK

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6 During de-collaring


6.2 Electrical monitoring during the whole process

7 On the coils, C03 first, then C02

7.1Thorough visual inspection, on both sides (inner and outer radii), look for cracks and other surface

defects, take pictures

7.2 Carry out metrology measurements (azimuthal dimension, radius, length key to key, total length)

7.3

Depending on the results of the electrical tests carried out at 2.4 and 5.3, repeat them on the same QH

circuit, exact test conditions to be discussed. Carry out the tests on the other QH circuit of C03 (think

of using IR camera)

Carry out other standard electrical tests, inductance, resistance, splices, …

X.X To be continued …

8QUICK

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Content





Paschen tests





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Cold mass assembly

Axial preload on coil heads Screws still loaded as at construction (30 Nm,

checked with torque key)

Yoke gap (measured prior to cutting of the shells) Nearly closed (comprised between 10 and 160 𝜇m

between the 2 holes, and along the entire length of the assembly)

Collar nose stress (strain gauges), comparison with stress prior to cold tests, see slide #17

Cracks in anti-torsion bars (bed of the bus bar housing), see slide #12

Large amount of information and pictures here: https://edms.cern.ch/document/2150670/1


Yoke gap measurement

Courtesy H. Prin et al.

https://edms.cern.ch/document/2150670/1

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Cutting of the shrinking cylinder


Done at the central workshops on a CNC milling machine (EN-MME, thank you!)

Milling in progress Crack appearing at the root (when cutting is

well advanced) after plastic deformation

has occurred

11

Courtesy H. Prin et al.

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Disassembly

Side Up, cracks were noticed on the

anti-torsion bars. This was never seen

before!

Side Down, no crack, nonetheless the

anti-torsion bars show waves (out-of-

plane defromation)


More information included in EMDS: 2150670

Prepared by O. Housiaux

bed of bus bar housing

The cracks are attributed to the sudden shear

off and rupture of the shrinking cylinder at

the root side at the end of the cutting. It is

accompanied by a small and rapid movement

upwards of the top shell and ½-yoke, as if it

were resulting from a shock

https://edms.cern.ch/ui/#!master/navigator/document?D:100368142:100368142:subDocs

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Content


Part 1: Disassembly and Post Mortem Analysis

Quality control plan



Paschen tests


Investigations on resin system

Part 2: Revised Project Plan

WUCD process



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Collared coils measurements


CC dimensions and tool description

Diameter RightDiameter Left

The tool is assembled around the collared coil (using hinge and screws)

There are 8 LVDT distance sensors (L1 to L8) that measure 6 dimensions:

Diameter: Horizontal, Vertical, Left 37deg, Right 37deg;

Height: Left, Right

Sensor head features flat round cross-section of 4.75 mm diameter

Each measurement starts (and finishes) with the calibration

Collared coil is measured in at least two runs (due to supports)

Repeatability is very good, average deviation between two measurements below 10 𝜇m

Large amount of information on collared coils assembly here: https://edms.cern.ch/document/2153881/1

Courtesy D. Pulikowski and J.L. Rudeiros Fernandez


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Dimensions are given before and after magnet testing (* size of collars, as

manufactured, unassembled)

188.15

188.25

188.35

188.45

0 1000 2000 3000 4000 5000 6000

Dim

ensi

on (

mm

)

Collar pack position (mm)

Diameter HorizontalDiameter Horizontal

181.9

182.1

182.3

182.5

0 1000 2000 3000 4000 5000 6000

Dim

ensi

on (

mm

)


Diameter Vertical, Left, and Right Diameter Vertical

Diameter 37deg Left

Diameter 37deg Right

69.9

70

70.1

70.2

0 1000 2000 3000 4000 5000 6000

Dim

ensi

on (

mm

)


Height Height Left

Height Right

188.15

188.25

188.35

188.45

0 1000 2000 3000 4000 5000 6000

Dim

ensi

on (

mm

)


Diameter HorizontalDiameter Horizontal

181.9

182.1

182.3

182.5

0 1000 2000 3000 4000 5000 6000

Dim

ensi

on (

mm

)


Diameter Vertical, Left, and Right Diameter Vertical

Diameter 37deg Left


69.9

70

70.1

70.2

0 1000 2000 3000 4000 5000 6000

Dim

ensi

on (

mm

)


Height Height Left

Height Right

Before magnet testing After magnet testing

Nominal* = 188.24 mm – Measured* = 188.295 mm Nominal* = 188.24 mm – Measured* = 188.295 mm

Nominal* = 182 mm – Measured* = 181.916 mm Nominal* = 182 mm – Measured* = 181.916 mm


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CC dimensions before and after magnet testing

-0.150

-0.100

-0.050

0.000

0.050

0.100

0 1000 2000 3000 4000 5000 6000

Dim

ensi

on

(m

m)


Diameter Horizontal and VerticalDiameter Vertical

Diameter Horizontal

-0.150

-0.100

-0.050

0.000

0.050

0 1000 2000 3000 4000 5000 6000

Dim

ensi

on

(m

m)


Diameter Left, and Right Diameter 37deg Left


-0.100

-0.050

0.000

0.050

0 1000 2000 3000 4000 5000 6000

Dim

ensi

on

(m

m)


Height Left and Right Height Left

Height Right

Deviation after-before of CC

dimensions (positive values indicate

enlargement)

After cold tests

Before cold tests,

i.e. after collaring


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De-collaring


De-collaring of GE-CC01 – Summary of mechanical measurements

3 x Instrumented collar packs:

2 x Strain gauge per instrumented collar

Collar nose

Shimming plan & estimated max stress (mock-ups)

Courtesy J.L. Rudeiros Fernandez

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De-collaring


De-collaring of GE-CC01 – Summary of mechanical measurements

-160

-140

-120

-100

-80

-60

-40

-20

0

Aftercollaring

Aftershell

welding

Aftermagnettesting

Aftercutting of

theshells

Colla

r nose

str

ess (

MP

a) CCS1

CCS2

CM2

CNCS2

The stress values computed from the

collar nose strain gauges increased

after shell welding

With the exception of one strain gauge,

and while the magnet remained

assembled, no significant variation was

observed in terms of strain before and

after magnet testing

A relative decrease of the collar nose

stress values between the respective

free-state collared coils (i.e. outside the

magnet yoke) might indicate plastic

deformation within the system during

assembly and/or magnet testing

Magnet testing

Two sets of measurements

(CM1 and CNCS1) were lost

at some stageCourtesy J.L. Rudeiros Fernandez

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Calculated Midplane Excess before collaring and after de-collaringGE02


-0.050

0.000

0.050

0.100

0.150

0.200

0.250

-300 700 1700 2700 3700 4700

Azi

muth

al e

xce

ss (

mm

)

Coil length (mm)

MPL Before collaring

MPR Before collaring

MPL After decollaring

MPR After decollaring

-0.150

-0.100

-0.050

0.000

0.050

0.100

0.150

0.200

-300 700 1700 2700 3700 4700

Azi

muth

al e

xce

ss (

mm

)

Coil length (mm)

MPL After decollaring - Before collaring

MPR After decollaring - Before collaring

L+R After decollaring - Before collaring

-0.200

-0.100

0.000

0.100

0.200

0.300

-300 700 1700 2700 3700 4700

Azi

muth

al e

xce

ss (

mm

)

Coil length (mm)

MPL Before collaring

MPR Before collaring

MPL After decollaring

MPR After decollaring

-0.100

-0.050

0.000

0.050

0.100

0.150

0.200

-300 700 1700 2700 3700 4700

Azi

muth

al e

xce

ss (

mm

)

Coil length (mm)

MPL After decollaring - Before collaring

MPR After decollaring - Before collaring

L+R After decollaring - Before collaring

19QUICK

GE03Courtesy D. Pulikowski

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Interpolated Outer Radius before collaring and after de-collaring


-0.050

0.000

0.050

0.100

0.150

-300 700 1700 2700 3700 4700

Inte

rpo

late

d O

ute

r R

adiu

s

(mm

)

Coil length (mm)

ORLeft After decollaring - Before collaring

60.600

60.700

60.800

60.900

61.000

61.100

-300 700 1700 2700 3700 4700

Azi

muth

al e

xce

ss (

mm

)

Coil length (mm)

ORRight Before collaringORLeft Before collaringORLeft After decollaringORRight After decollaring

-0.050

0.000

0.050

0.100

0.150

-300 700 1700 2700 3700 4700

Inte

rpo

late

d O

ute

r R

adiu

s

(mm

)

Coil length (mm)

ORLeft After decollaring - Before collaring

ORRight After decollaring - Before collaring

60.750

60.800

60.850

60.900

60.950

61.000

61.050

-300 700 1700 2700 3700 4700

Azi

muth

al e

xce

ss (

mm

)

Coil length (mm)

ORLeft Before collaring

ORRight Before collaring

ORLeft After decollaring

ORRight After decollaring

QUICK

GE02 GE03Courtesy D. Pulikowski

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Conclusions on coil and collared coil metrology

1. The deformations measured on the collared coil assembly (negative in

horizontal, and positive in vertical directions) are interpreted as plastic

deformation of the assembly (“small”)

2. The increased outer radius (coherent with the collar deformation) and

midplane excess are interpreted as plastic deformation of the coil

(“small”)

3. The midplane excess is calculated as a function of the outer radius

and surface of the loading plate, and therefore deviates due to varying

arc curvature

4. The observed deviations in coil geometry are small in comparison with

tool error of ±41𝜇m


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Coil visual inspection – G03 (“good”)

F. Savary @ 78th Meeting of the HL-LHC TCC 22Magnet testing

After impregnation After de-collaring

Straight section

Interfacial crack

initiation?

Wedge Wedge*

Interfaces

Poor bonding ↔ Low interfacial strength

Straight section – Inner radius

Courtesy J.L. Rudeiros Fernandez et al.

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In general terms, superficial delamination and crack propagation are observed all around the surface of the coils.

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CS

Top picture coil orientation

Interface

Interface

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CS


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CS


Crack initiation

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After de-collaring

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Coil visual inspection – G02 (“quench limitation”)



Superficial delamination and crack

propagation are observed.

Courtesy J.L. Rudeiros Fernandez et al.

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CS


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NCS


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Coil visual inspection – CR07 (“prototype”)


After de-collaring

Straight section

NCS

CS

Inner radius

Less (visible) damages, i.e. surface defects, than GE02/03Courtesy J.L. Rudeiros Fernandez et al.

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Coil visual inspection – Coils 120 & 121 of SP107

33

More (visible) damages (endoscope), i.e. surface defects, than GE02/03

Magnet testing

After impregnation After cold testing

Straight section

C 120

C 120

C 121

Coil 121 – NCR EDMS: 1967292:https://edms.cern.ch/document/1967292/1

Delamination

Delamination

Crack

propagation



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Magnet testing


Straight section

C 120

C 120

C 121


Delamination

Crack

propagation

Crack

propagation


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35


Magnet testing


C 117


Delamination



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Conclusions on coil visual inspection


1. Superficial delamination and cracks seem to be a general feature of

CTD-101K impregnated coils

2. Interfaces are crack initiation features, possibly due to shear and

differential thermal contraction, higher probability of voids, or presence

of poorly wetted regions

3. There is no evidence of superficial delamination or crack propagation

influencing the performance of the magnet

4. The behaviour of SP107 during the next test campaign, will be

informative, as severe cracking and delamination were observed

through the analysis of the inner radius surfaces

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Crack formation in pure CTD-101K vs cooling rate

Slow cool down vs. thermal shock (play video with sound to hear crack formation)


Courtesy M. Michels

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Left sample:

slow cool down (~ 15 min)

no crack

Right sample:

Immediate immersion in LN2

many cracks

Vertical sample:

No crack formation after partial immersion in

LN2 following slow cool down

Crack formation in pure CTD-101K vs cooling rate


A very simple experiment, which however, is telling us a lot: it is possible to

preserve material integrity by simply applying a slow cool down process

It is a worst case scenario, as we have tested pure resin (reinforced resin

should be tested, also with reacted fiber)

Courtesy M. Michels

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Content


Part 1: Disassembly and Post Mortem Analysis

Quality control plan



Paschen tests


Investigations on resin system

Part 2: Revised Project Plan

WUCD process



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Goal Understand how QH to coil insulation can affect breakdown voltage, in particular in presence of partial air (or

helium) pressure, and possibly demonstrate infiltration/percolation of helium in the impregnated coil

Plan Test a virgin coil (CR02, produced at the beginning of the development programme, it has never been tested at

cold, and therefore has never seen helium)

Then, test a coil of the hybrid assembly (« rapidly », after it has seen helium in SM18)

Test protocol Put the coil in a vessel, and create pressure excursion from 0.01 Pa ( 10-4 mbar) to 50000 Pa ( 500 mbar)

Apply a test voltage over 30 s with a ramp of circa 1 kV/min, with MEGGER1025

The two quench heaters are tested independently in pressure range [5.10-3 mb – 200 mb].


Paschen test on QH to coil insulation

Courtesy A. Foussat & J. Petrik

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DOI: 10.1109/TASC.2011.2179393


Test results for CR-02 (proto) [5.10-3 – 200 mbar]

41

Courtesy A. Foussat & J. Petrik

https://doi.org/10.1109/TASC.2011.2179393

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Test results for GE-02 (hybrid) [5.10-3 – 800 mbar]

QH Left: Paschen minima at 2 mbar, indicating a defect size of 0.4 mm. Multiple Paschen regimes were not observed CR-02 (not cold-tested), which may indicate progressive degradation of the insulation system in the case of GE-02

QH right: do not show a full Paschen curve. It seems that the minima is shifted towards higher pressure, 90 mbar, indicating a defect size of 80 𝜇m (that is radial, through insulation thickness)

F. Savary @ 78th Meeting of the HL-LHC TCC 42Courtesy A. Foussat & J. Petrik

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Conclusion of Paschen tests

For CR-02:

A breakdown voltage minima was found at 575 V @ 0.4 mbar

for a QH-Right, and 675 V @ 0.5 mbar for the QH-Left

Considering the minimum of the product P・d, as invariant in

air at 8 mbar ・ mm, then the minimum defect involved in the

breakdown in CR02 would be around 14 mm

For GE-02:

The breakdown voltage minima was found at 680 V for both

QHs, indicating the same gas conditions as for CR02, i.e.

presence of air, not helium!

F. Savary @ 78th Meeting of the HL-LHC TCC 43Courtesy A. Foussat & J. Petrik

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Content





Paschen tests





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1. 11T FE thermo-mechanical model

Objective: Investigate the impact of large delta temperature during the magnet cool down

and warm up, on coil stress


CoilsShell

Top

Bottom

Top splice

Coil head

Temperature measurements during testing

MBHSP109

Sta

tion

Lon

g

SP109 – 3rd Cool down

(i.e. 2nd thermal cycle)

Vertical ΔT

Shell

Radial

ΔT


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The FE models

Sta

tion

Lon

g

2in11in1

Geometries

Temperature is

imposed, for each

step, based on

experimental

measurements, in

the coil and the

shell. Thermal Model (Temperature Field)

ANSYS Steady-State Thermal

Mechanical Model

(Stress – Strain) ANSYS

Static Structural

Body Temperature


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Preliminary results

Sta

tion

Lon

gMeasurement

0

50

100

150

200

250

300

350

-1.5

-1.4

-1.3

-1.2

-1.1

-1

-0.9

-0.8

-0.7

3 8

Te

mp

era

ture

(K

)

Colla

r n

ose

str

ain

(S

ca

led

)

Cool Down - Simulation Steps

Collar nose strain

ΔT (Tcoil-Tshell)

Shell Temperature

Simulation

SP109 – 3rd Cool down (i.e. 2nd thermal cycle) 1. In terms of the global mechanical

response, the relative increase of the measured strain in the collar nose, can be replicated by the thermo-mechanical model

2. The model doesn’t account for dynamic and fracture behaviour (e.g. high thermal strain rates, crazing, cracking and debonding), potentially present within the coil due to thermal shocks or high rates of temperature variation, during the cooling down or warming up of the magnet

Considerations

The scaling was considered because of (1) uncertainty in material parameters (like thermal contraction and

variation of stiffness vs. temperature, and (2) unexplained stress variation , as measured for SP109 between

end of collaring and beginning of cool down) Courtesy J.L. Rudeiros Fernandez

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Content





Paschen tests





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Connection sideCFB

300 K (for CD)

or 80 K (for

WU) helium

gas inlet

through N-line

(TT 161)

300 K or 80 K helium gas injected

in cold mass on connection sideHelium gas

exits the

cold mass

by a M-line

(TT 150)

The helium gas flows

through holes in the cold

mass (but not in the

beam tube, nor in the

heat exchanger tube)

The head on the connection side has

seen the largest thermal gradient

This is also the part that limited the

quench current in the coil after the first

thermal cycle

Standard Warm Up and Cool Down process in SM18

Horizontal test benches

F. Savary @ 78th Meeting of the HL-LHC TCC 49Courtesy G. Willering

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Large thermal

gradient during

first warm up

Controlled thermal

gradient during warm up

Nb-Ti magnet warm up cycle using mainly

300 K He gas, also used for the 11T

prototype, and 11T hybrid magnet

New: manually controlled warm up cycle

using a blend of 300 K and 80 K gas

This delta T control has been implemented in

automated process by TE-CRG and is ready for the

cool down of the 1st series magnet, LMBHB002 (cool

down expected next week), see next slide

Note that the TT821 probe in the middle of the magnet

shows that the temperature gradient is entirely on the first

half of the magnet, and possibly an even a shorter part of it

The local gradient may be much higher than 150 K / 5.5 m

Cool down and warm up process improvement

F. Savary @ 78th Meeting of the HL-LHC TCC 50Courtesy G. Willering

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CERNOX

Temperature

probe on cold

mass

Maximum delta T regulated between 3 probes: TT150 – gas inlet temperature (in CFB)

TT161 – gas outlet temperature (in CFB)

New CERNOX placed on the cold mass on the CFB side

Control For the first cool down/warm up a delta T of 30 K will be requested

Technical difficulty / risk Mixing of 80 K + 300 K gas happens just before the magnet

Restarting the cool down or warm up phase can only be done with

80 K or 300 K gas, so if the cool down/warm up is interrupted

(accidentally) in the middle of the process (for example at 200 K), it

leaves little options than temporary exceeding the requested delta T,

even at minimum gas flow which is rather high (~ 30 g/s)

Details of the process explained in EDMS 2136536

TT161TT150


New cool down & warm up process

Courtesy G. Willering

Warm thanks to TE-CRG (N. Guillotin, J-P. Lamboy et al.) for the implementation


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Content





Paschen tests





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Dates of availability for tunnel

S3: LMBHA0022020-02-24

CC06

C10 C14

CC07

C15 C16


S1: LMBHB0022019-08-22

CC02

C01 C05

CC03

C06 C07

S4: LMBHB0032020-04-15

CC08

C17 C18

CC09

C19 C20

S5: LMBHB0042020-07-20

CC10

C21 C22

CC11

C23 C24

S6: LMBHA0032020-09-28

CC12

C25 C26

CC13

C27 C28

S2: LMBHA0012019-12-16

CC04

C08 C09

CC05

C12 C13

Magnets equipped with impregnated QH

Magnets equipped with external QH

In replacement of CC0153

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Detailed schedule


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Detailed schedule – Last step prior to installation


The end of stripping date of Series 4 is later than in the baseline schedule, by 8

weeks (is 15.04.2020, was 20.02.2020)

An analysis was made with the LS2 team in order to determine the impact of this,

see next slide

55

Ok

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Outcome of the analysis by LS2 team

• Scenario 2 is preferred

• The installation of a 11T dipole full assembly after LS2 would require about 41 weeks, broken down as follows:

• 6 weeks for sector warm-up + ELQA @ warm

• 25 weeks for 11T installation (MB removal + preparation works + 11T installation + TCLD installation)

• About 10 weeks for sector cool down + ELQA + powering tests (and this does not take into account the part commissioning)


Delay in S 6-7 Delay in S 7-8

Scenario 1: First in S 6-7 -8 Weeks +14 Weeks

Scenario 2: First in S 7-8 +8 Weeks -2.5 Weeks

56Courtesy M. Bernardini, S.E. Bustamante

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A few concluding words

It is not obvious to establish clear relationship between the

observations collected during the dismounting activities and the

degraded performance of the limiting coil (head on the connection

side of coil GE-02)

It is clear that a rapid cool down is not good, and that a slow cool

down instead allows preserving materials (resin experiment)

Work is ongoing with

Resin experiment (aiming at quantitative results, not only qualitative)

Investigations on resin and impregnation process


Non destructive examination of coils (dye penetrant test)

See action items in additional slides


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Thank you for your attention!


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Action item 2

SP107

1. Thermal cycling of collared coils

in liquid nitrogen finished at the

cryo-lab. (10 cycles + 1), in

controlled WUCD conditions with

ΔMAX = 60 K

2. To re-assemble the CC in a model

structure for a new cold tests

campaign. We would like to have it

on the test bench in early June

(schedule to be developed). With

controlled WUCD conditions

Goal

1. Understand impact (if any) of

thermal stresses, which are adding

to mechanical compression

stresses, applied to the QH-to-coil

insulation system

2. Check for possible degradation of

the conductor performance (as

observed in SP109, due to high

MIITs and thermal cycles)


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Action item 3

SP109

Carry out electrical tests at cold (around 200K) under He gas at 1 bar, at a test voltage to be confirmed in the range of 1.5 – 2 kV

Tests on SP109 expected to bedone in 2019-Q3. Detailed plan to be developed

Adaptation of a vertical test stand needed (HFM?)

Goal

Check

QH-to-coil insulation system

Coil-to-ground insulation system

Determine an electrical test to be applied as final acceptance test at the end of the cold tests campaign of the series magnets


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Action item 4SP108

1. Will be made with 2 new coils with(impregnated QH). We need to plan the fabrication of 2 coils (coil #124 isdone/finished)

Goal1. The objective is to reproduce the

fabrication and assembly conditions of SP107

For SP108, SP201, and SP202, verify Possible degradation of the conductor

performance due to high MIITs quenches(High T hot spots), and thermal cycles, as observed in SP109

Electrical integrity at cold, coil to ground, coil to QH

And why not introducing the capacitive gauges (to be checked with Arnaud F.)

2.c For exploration purpose


2.a Will be made with PIT conductor, and

external quench heaters

2.b SP201 with nominal coil stress

conditions (<150 MPa @ mid plane,

i.e. <300 m azimuthal excess)

2.c SP202 with lower coil stress

conditions, between -30 and -50 MPa

SP201 and SP202

Detail plan for SP108, SP201, and SP202 still to be developed (by mid May), the goal being to

complete the 3 models, and their testing, by end 2019 (this is likely too optimistic)61

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Action item 5 – conductor & cable characterization

Determine irreversibility limits of conductors and fatigue behavior under thermal (≈10 WUCD) and electromagnetic (≈1000 EM cycles) conditions

Carry out comprehensive characterizations of the behavior under transverse stress of final strands and cables, including:

Assessment of maximum allowable stress at warm on cables (at FRESCA)

Assessment of reversible and irreversible degradation vs. stress at cold on strand (University of Geneva setup) and cables (at FRESCA and Twente University)

Assessment of thermal cycling on cables (TBD)

Assessment of stress cycling at cold on cables (at Twente University)

Assessment to be accompanied by micrographic examination to determine the onset and extent of filament cracking on the final strands (at FSU/ASC and CERN/EN/MME)


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Action item 6 – Numerical modeling & analysis

Establish coherence and reference numerical models for the single, and two-in-one structure (for MQXFB also) Material properties (mechanical, physical)

Level of detail (coil bloc, cable, …), meshing

Boudary conditions

Mechanical and thermal stresses

Format for the outputs (strain/stress, average vs local stress, @ pole/mid plane, radial direction, assembly to operation conditions, …)

Make sure the link with the mechanical measurements will be possible and relevant

Develop an understanding and analyze thermal stresses that arise in magnetcoils during various phases of testing and operation (WUCD, …) Develop an instrumentation plan such that comparison and validation will be possible

Assess in-coil performance of conductors, i.e. understand the degradationsobserved after Thermal cycles

High MIITs quenches resulting in high hot spot temperature


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MBH-hybrid second, and third cooldown

Performance

- After thermal cycle, the magnet

performance was limited by a

single point in the magnet

- Strong ramp rate dependency

- All observations, and magnet

behavior, point to local damage

to the Nb3Sn cable

- At 4.5 K, the quench current is

still @ 12.2 kA

Retraining memory

- Quench 22 is seen as a

training quench, in the other

head (NCS) of coil C03

- All the other quenches were in

the weak spot. Otherwise, up to

12.5 kA the mechanical training

memory seems to be good

Localisation of degradation

- In the head of the upper coil

(C03) on the connection side.

In segments 2 to 3 of the

quench antennas

- From quench 10 to 30, all but

one started in this location


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LMBHP001 – Hybrid – first cool down

Significantly better training in first cool

down than all earlier model magnets

Higher coil limit at 4.5 K, 300 A higher

than for the best model magnet

“Clean” training curve

No detraining

Single quench to nominal current

Even at 4.5 K reaching almost ultimate current level,

showing good temperature margin for nominal operation

94% of the conductor short sample was reached @ 4.5 K

Significantly better than the prototype, which had a

limitation at 8 kA


11t hybrid assembly 1. disassembly and post mortem analysis … · 2019. 8. 7. · part 1:...

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