from 3.5 tev to 7 tev: solution for the interconnect consolidation francesco bertinelli cern –...

From 3.5 TeV to 7 TeV:Solution for the interconnect

consolidationFrancesco Bertinelli

CERN – Technology Department – MSC Group

20 minutes presentation, 10 minutes discussion: 26 slides

CERN Machine Advisory Committee2nd Meeting – 26 April, 2010

Who is studying the solution and how? What does the new design look like? How will it be implemented?

http://doc.cern.ch/archive/electronic/cern/others/PHO/photo-bul/bul-pho-2007-046_01.jpg

26 April, 2010 2nd MAC – From 3.5 TeV to 7 TeV- Francesco Bertinelli

2

Splices Task Force

Mandate November 2009 (35th LMC, 4 Nov. 2009)To review the status of all superconducting splices in the LHC machine and prepare the necessary consolidation actions for 7 TeV operation.

Time frame:6-8 months starting November 2009. Originally to prepare for a shutdown 2010-2011: plans for the main IC splices maintained after Chamonix2010 (→ shutdown 2012).

Participation: 12 members from different CERN groups and departments. P. Limon (Tevatron), K.-H. Mess (Hera), RHIC this week

www.cern.ch/splicesF. Bertinelli, N. Catalan Lasheras, P. Fessia, C. Garion, S. Mathot, A. Perin, C. Scheuerlein, S. Sgobba, H. ten Kate, J.-P. Tock, A. Verweij, G.

Willering

https://espace.cern.ch/lhcsplices/default.aspx


3

Reminder from Chamonix2010Energy tRB [s] Max. Raddit,RB [mW] tRQ [s] Max. Raddit,RQ [mW]

3.5 TeV 50 76 10 80

5 TeV 75 43 15 41

7 TeV 100 11 20 14

by considering unbiased data, ~15% splices would need redoing from R16 ( = copper stabiliser continuity) alone;

but segment measurements cannot identify them precisely enough (for MQ in particular), plus need to open all M sleeves for a given segment, estimate ~90% of sleeves;

if in addition we consider repairs from visual and preference towards systematically adding a shunt/clamp, we conclude:

Open all W interconnects and cut open all M sleeves, make local R16 measurement, redo ~20% splices, add shunt to 100% splices

from

A. V

erwe

ij


4

Insulation and transversal restraint: injection molding in RYTON (PPS)

Sn-Pb solder for

shunt

Mechanical clamping (not

present in Tevatron and Hera …)

but same Sn-Ag solder where we

redo splices

For latest update see Splices Task Force

meeting no.17:https://espace.cern.ch/lhcsplices/Meeting%2017/default.aspx

The consolidated main IC splice

https://espace.cern.ch/lhcsplices/Meeting%2017/default.aspx

https://espace.cern.ch/lhcsplices/Meeting%2017/default.aspx


5

Rationale behind the design i/ii “Flexible” shunts

• e.g. Braids or lamellar construction (EMS-DE)• Should adapt to existing defects• Avoid in-situ machining and copper swarf• Stress-free (or as low as possible) Sn-Pb interface: limit risk of

potential degradation• Designed for 13 kA. Critical parameters are thickness and

unsoldered length (→ difficult to achieve flexibility with 10 mm ...)

Solder 60Sn-40Pb• Lower melting point than Sn-Ag• “classic” solution (Tevatron, Hera)• ... but additional safety requirements: Safety Commission

already involved


6

Rationale behind the design ii/ii Mechanical clamp

• Shall not depend on solder strength• Designed to survive ramp-down time

Insulation• Combines electrical function and mechanical restraint to

bending• Allows efficient cooling from LHe• Ease of assembly• Current question: Include additional insulation?

nQPS• Build-in monitoring of segment resistances in time• Dedicated resistance measurement campaigns scheduled in

Operations General approach: seek redundancy and safety, do not want to

intervene again (but no paranoia ...)

2nd MAC – From 3.5 TeV to 7 TeV- Francesco Bertinelli

716 March, 2010

13 kA IC: 3 directions for development

13 kA coordination

P. Fessia

13 kA interconnect

re-development

Shunt development

Insulation development

~500 splices redone in 2008-09

Improved process and QC Further improvements:

• loss of solder• avoid cutting spools• Process speed

Shunt geometry Solder options Soldering process

• Inductive (as for splice)• Resistive oven (“classic”)• “Fast” resistive

Mechanical clamp

FEA computations Materials, availability, costs Design insulation test


8

13 kA splice and process improvements

Optimise temperature profile• Thermocouples• Optimise geometry of inductive

coils

Simplify mechanics for easier use• verify the minimum force to get a

good joint (samples at 3 level of force 50%, 25%, 15%) → avoid cutting spools

• Include external water cooling after soldering → faster process


9

Eight measurement points located on the upper surface of the bus-bar.

Temperature sensors: Thermocouples type K with Inconel sleeve. Tester: Data logger by ATP Messtechnik (Sampling Time = 10s). Standard inductive soldering procedure. Kapton stripes around the interconnection to avoid Sn flow off.

Precise measurement of temperature profile


10

A simplified 3D magneto-static model of the inductor and of the bus-bar has been done.

The aim of the model is to understand the relationship between the field and temperature profiles along the interconnection, during the soldering plateau.

Optimisation of temperature profile


11

Shunt soldering process

Slow process, resistive oven

Fast process development.

Resistive micro welding

Room temperature tensile testing [kN]

6.1 ± 0.9 6.5 ± 0.2

Liquid nitrogen tensile testing [kN]

7.1 ± 0.9 7.9 ± 0.1

Liquid He tensile testing [kN]

Resistive oven “Fast” resistive process Inductive soldering

(possibly several shunts in parallel)

Note: 550 N required


12

Baseline is 60Sn-40Pb, will be fully developed first Other studies will be performed later, same temperature as

60Sn-40Pb Verification of theoretical mechanical properties still to be

checked

Other alloys that we will study

Alloy Melting temp. rangeSn77.2-In20-Ag2.8 175-187 C

In96.8-Ag3.2 157 CIn90-Ag10 157-210 C

Sn62-Pb34-Sb0.5-Ag3 180-187 CIn80-Ag5-Pb15 142-149 C

2nd MAC – From 3.5 TeV to 7 TeV- Francesco Bertinelli

13

Insulation studies

Max displacement reduced from 0.25 mm to 0.06 mm

and displaced out of the connection and far from the

shunt

26 April, 2010


14

13 kA IC Quality Control Progressing in parallel to IC work First tests of electrical resistance

at warm Launching feasibility studies with

EMPA (CH) and BAM (DE)

Defect type 3

A B

Defect type 2

Defect type 1

Ultrasonics test

Shunt contact resistance


0 2 4 6 8 10 12 14 16 18 200

10

20

30

40

50

60

Current (kA)R

unaw

ay t

ime

(s)

Quadrupole busbar, constant current 2 shunted defects measured (3 mm thick, 6 –

10 mm non-soldered length)

No shunt

Shunted

Shunts show a large improvement of stability However, results are not directly applicable to the LHC

machine situation: → simulation work

FRESCA results and “proof of principle” test See L. Bottura 27 April

15


16

In SM18 two special SSS cold masses in series (MQM for Q8 and Q9)

the M1 and M3 busbars are not connected to the magnet, hence no inductance during splice testing

in preparation for July 2010

Final Validation Test


17

Review

Formal reviews will be organised:• for the main IC splice design and process• two stages: before Validation Test and end 2010• Composition?


18

Scenario for implementation Series experience = real data

• Average 30 IC activities per week• Capacity designed for 40 IC activities per week

Plan 2012 intervention to 50 IC activities per week (ambitious goal)• repair ≠ new • once work starts there will be huge pressure, many intervenants,

little possibility for adaptations → do not count on learning curve• So many aleas at this stage → resist temptation to “squeeze”

planning too much already now Organise work as a train

• Proceed to adjacent sector (→ do not jump), extend over 2-3 sectors

• keep General Access mode as long as possible (→ cooldown and power as late as possible)

• there will be additional work and surely unexpected work (→ Special Interventions Team)

See K. Foraz 27 April


19

Sector 1-2 production

0

5

10

15

20

25

30

35

1-M

ar-0

7

15-M

ar-0

7

29-M

ar-0

7

12-A

pr-0

7

26-A

pr-0

7

10-M

ay-0

7

24-M

ay-0

7

7-Ju

n-07

21-J

un-0

7

5-Ju

l-07

19-J

ul-0

7

2-A

ug-0

7

16-A

ug-0

7

30-A

ug-0

7

13-S

ep-0

7

27-S

ep-0

7

11-O

ct-0

7

25-O

ct-0

7

8-N

ov-0

7

Num

ber o

f IC

per

wee

k

Solder main splices

Weld M sleeves90% work in 11 wks …

… but last 10% work in 9 wks

Series experience: soldering busbars

from P. Fessia


20

Length of shutdown: estimate @50 IC/week

Closing W

VAC sector leak test

Holes and NC

wk 9 wk 10 wk 11

Holes and NC

wk 13 wk 14

Welding M sleeves

wk 12

Repairs

wk 7

ELQA

Opening W

Cutting M sleeves

QC, R16, segment resistance

wk 6

Sect

or 7

-8

wk 3 wk 4 wk 5wk 1 wk 2

VAC QC bellows and protection

Spools and insulation

Solder shunt

Desolder/resolder/shunt splices

QC Welding

wk 8

QC splices/shunts

The next sector ends 5 weeks later and so on ...


21

Activity QuantityExisting at

CERNTo come in

additionComments

Opening W 100% 1 20 FSUs as in 2008-09 (15 openings or closing per day)

VAC QC bellows and protection 100% 2 3 Project Associates?

Cutting & deburring M sleeves 100% 6 5 1 Team Leader, 7 mechanics cutting, 3 helpers

QC, R16, segment resistance 100% 2 4 Project Associates?

Solder shunt 100% 5 5 Project Associates?

Desolder/resolder/shunt splices 20% 2 4 Project Associates?

Spools and insulation 10% 2 4 Project Associates?

QC splices/shunts 100% incl. incl.

ELQA 100% 4 10 Project Associates?

Welding M sleeves 100% 5 5 EN-MME

QC Welding 100% 2 3 EN-MME "Institut de Soudure" visual control

Closing W 100% incl. incl.

Other 15 5 VAC (40-30), thermometers, IC QC, logistics, coordination …

Totals 46 68

DN200 4 sectors 2 15 Organise DUBNA and FSU

Resources for splices consolidation

Need to maintain a balance between “existing/experienced” resources and “newcomers”


22

Cost estimate of splices consolidationOnly material costs: FSU and Project Associates included, EN-MME jobs for weldingAssume all 8 sectors consolidated (start IC work in January 2012, scenario 49 weeks)

NOT included: splices development work in 2010 and 2011 "other" shutdown activities (e.g. DN200, etc.): note important implications on availability of CERN personnel VAC, ELQA, Cryo costs unknown complications/costs (at this stage) due to radioprotection constraints

kCHF %

Main components 2080 14%

Production tooling 1890 13%

Interconnection workOpening and closing W bellows, repair screens 2300 16%FSU and EN-MME welding 5100 35%

Quality Controlsplices and welding 1200 8%Project Associates Team (10 people) 880 6%

Logistics 995 7%

Vacuum activities … my first guess: 6 FSU - 1 year, 700 kCHF

ELQA activites … my first guess: 10 Proj Ass., 880 kCHF

Cryogenic activities …He for pressure tests 250 2%

Total 14695 100%

21.4 MCHF plus preparation in 2010-11


23

DN200 (arc pressure relief nozzles) 7-8, 8-1, 2-3, 4-5 (partly)Connection cryostats 7-8, 8-1, 2-3, 4-5Vacuum leaks 3-4, others?N line connections to check 7-86kA praying hands to check 7-8Spool connections to investigate/repair 8-1, others?Replace magnets? (damaged nested bellows, SC cable, quench heaters, IFS box …)

~2-4 cases (e.g. QBBI.10R7, QBQI.10L5 araldite repair)

Early dipole Busbars 1 to 10 in SSS Mainly 7-8Y-lines 7-8, 8-1, others?DFBA flexibles (and some splices?)Inner triplets copper braids Points 1, 2, 5 and 8Prepare and replace Q5L8 (SC corrector)

4-5

Stand Alone Magnets He guards 7-8, 2-3Damaged radiation/thermal screens All sectorsPIMs RF ball test, a few preventive

replacements, no global replacements?… 35 NCR, “closed with warning”, HWC cases

Additional magnets/splices work

a considerable amount of non-standard work !!!


24

Shutdown and resources issues Moving magnets at Point 3 for collimators?

• Same resources involved → there will be an inevitable time impact in the 2012 shutdown

• Surface preparation work (busbar area setup and work, ….) New Collaboration Agreement for Project Associates

• we will first use all available resources on site, …• … but some resources will need to continue other critical

activities• looking to set up a new Collaboration Agreement (“a la” Krakow

Institutes for series production)• otherwise FSUs• and integrate first persons with existing resources already in

2010 Xmas 2010 “Technical Stop”:

• Could we consolidate 1 sector? → power and test the consolidated solution (and magnets), learning could allow optimization of 2012 shutdown

• … or (not “and”) some of the “additional magnets/splices work”• If so needs to be decided by June 2010 (advice?)


25

Analysis of circuits 13 kA: inside DFBAs in particular 6 kA analysis started:

• inventory of splices present: Points 2 and 4 done

• Study failure mechanisms (multiple failures), quench detection, energy extraction → risk analysis

Slow progress (resources taken on LHC startup)Praying

hands too!


26

Conclusions

13 kA IC: we have a candidate design, first test evidence is promising, Final Validation results by August

Scenario for 2012 Shutdown for 13 kA IC exists

Highlighted issues and current questions where advice is welcome

from 3.5 tev to 7 tev: solution for the interconnect consolidation francesco bertinelli cern –...

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