1. F. Borgnolutti November 14 th 2012 2 nd HiLumi Collaboration Meeting Frascati HQ coils: History & Performance

2. Outline HQ Coil Design Main issues met during HQ coils fabrication HQ Coil production summary (coil 1 to coil 20) Tests results Next generation of HQ coils (starting from coil 21) Summary 11/14/2012HQ Coils: History & Performance2

3. HQ Coil Design 11/14/2012HQ Coils: History & Performance3 Coil main parameters: 120 mm aperture diameter 1 m long 20 turns in L1 / 25 turns in L2 87 m of cable/coil Cable: o 35 strands o Width = 14.75 mm o Mid-thickness = 1.375 mm o Keystone angle = 0.75 º o Insulation thickness = 100 um Magnet Expected Performance: Short Sample gradient of 214 T/m @ 1.9 K “ “ 195 T/m @ 4.4 K Nominal Ramp rate 20 A/s H. Felice et al., “Design of HQ – A High Field Large Bore Nb3Sn Quadrupole Magnet for LARP”, IEEE trans. On Applied Supercond. VOL. 19, NO. 3, JUNE 2009

4. Status of the HQ coil production From May 2009, 20 HQ Coils have been fabricated 5 tests involving 9 coils (coil 1 to coil 9) have been performed in a quadrupole structure at 4.4 K (HQ01a-b-c-d-e ) o HQ01e has been tested a second time (HQ01e-2) at CERN at both 4.4 K and 1.9 K. 3 tests involving 3 coils (coil 12, 13 and 15) have been performed at 4.4 K in the mirror structure (individual coil test, HQM01-02-04) 11/14/2012HQ Coils: History & Performance4

5. Main issues met during the coils fabrication 11/14/2012HQ Coils: History & Performance5 Broken strands in coil 10 (post reaction) Implementation of an axial gap (0.76 mm for coil 3 to 13, 3.2 mm from coil 14) Coil springing out of the reaction fixture  Coil expansion/contraction Some concern Sign of high radial compression Coil 3 in the reaction fixture, after reaction Reduction of the strand diameter from 0.8 mm to 0.778 mm (Starting coil 14) Cable reduced by: 3.8 % azimuthally 2.6 % radially The coils still spring out from the reaction fixture (~2mm, half of what before making room for cable expansion)  Is the room left for expansion suitable? The pole gap in coil 17 stayed open  Effect of the braided insulation?  Problem during winding (winding tension)? Corrective actions Coil 20 COIL 13

6. Main issues met during the coils fabrication 11/14/2012HQ Coils: History & Performance6  Pole gap in the coils before and after reaction The pole gap seems optimum since it is at the limit of closing totally after reaction

7.  Weak electrical insulation between the coil and the coil parts (saddles, spacer,…) Main issues met during the coils fabrication 11/14/2012HQ Coils: History & Performance7 Recurrent insulation issues between the coil and the parts within the coil Weak insulation between the coil and the trace (arcing between the trace and the coil) Decrease coil compaction and increase insulation thickness under the trace Starting coil 17: Coating of the coil splice block and saddles parts ( 5 mils coating thickness) Some concern From coil 21: All the parts are fully coated with 10 mils ALO3 coating (10 mils coating thickness, voltage breakdown > 1 kV) Corrective actions The tolerance we ask for the flat surface of the pole pieces is 9 mils ±1 mil (0.23 mm ± 0.024 mm), but the tolerance for the pole piece of coil 21 was found between 6 and 9 mils (0.15 - 0.23 mm) what is acceptable for the field quality? What happen when the coil is energized and pulls on the coating (debonding?)? Coil 20 could give an answer..

8. Main issues met during the coils fabrication 11/14/2012HQ Coils: History & Performance8 It seems that only the second generation of cable was affected (starting coil 14): o Smaller strand diameter (from 0.8 mm to 0.778 mm) o Introduction of a core (8 mm*25 um) o 2 pass cable (cable fabrication, annealing, re-rolling) to 1 pass cable (strand annealing, cable fabrication)  Cable mechanically unstable (new issue?) Strands popping out when winding the L2 (unfavorable winding direction) Popped strands may cause strand and insulation damages: o For instance, coil 18 had a lot of inter-turn shorts because of popped strands Which of these modification contributes to make the cable mechanically less stable? Maybe a combination of the three…

9. HQ Coil production summary 11/14/2012HQ Coils: History & Performance9 Coil Number 1234567891011121314151617181920 RRP 54/61RRP 108/127RRP 54/61 108/127 (Ti) RRP 54/61RRP 108/127 (Ta doped) 108/27 (Ti) 108/127 (Ta) 0.8 mm diameter strand (cable width = 15.15 mm, cable mid-thickness = 1.437mm) 0.778 mm diameter strand (cable width = 14.75, cable mid-thickness = 1.375 mm, keystone = 0.75º No axial pole gap 0.76 mm axial pole gap3.2-3.3 mm axial pole gap Cable without a coreCable with stainless steel core (8 mm*25 um) Original ends designRevised end design Cable fabrication  annealing (200ºC)  re-rolling (2 pass cable) Wire annealed (185ºC)  cable fabrication (1 pass cable) All the parts (end saddles, poles pieces, spacers) are left uncoated End saddles are coated with ALO3 Tested in HQ01 Not tested Tested in mirror Structure Not tested Will be tested in HQ02 Will not be used H. Felice et al., “Impact of coil compaction on Nb3Sn LARP HQ Magnet”, IEEE trans. On Applied Supercond. VOL. 22, NO. 3, JUNE 2012 1 turn less in L1 & L2 to provide room for cable expansion Gap did not close Weak electrical insulation Broken strands Turn to turn short Wrong twist applied to L2 L1-RE key fully coated (10 mil) Good but not used matrimidCyanate- ester

10. Magnet test results 11/14/2012HQ Coils: History & Performance10 S. Caspi et al., “Test results of 15 T Nb3Sn quad. Magnet HQ01 with 120 mm bore for the LHC lumi. upgrade”, IEEE trans. On Applied Supercond. VOL. 22, NO. 3, JUNE 2012 M. Marchevsky et al., “Quench performance of HQ01, a 120 mm bore Larp quad. For the LHC upgrade”, IEEE trans. On Applied Supercond. VOL. 22, NO. 3, JUNE 2012 R. Bossert et al., “Optimization and test of 120 mm LARP Nb3Sn quad. Coils using magnetic mirror structure”, IEEE trans. On Applied Supercond. VOL. 22, NO. 3, JUNE 2012 G. Chlachidze et al., “Test of optimized 120mm Larp Nb3Sn quad. Coil using magnetic mirror structure”, IEEE trans. On Applied Supercond. VOL. 22, NO. 3, JUNE 2012 Coil Number Tested at Max gradient @ 4.4 K [T/m] % IssComment HQ01 a 1-2- 3 -4 LBNL15779Coil 2 damaged (arcing) b 1-4-5- 6 LBNL15377First quench, then c 1 -5-7-8 LBNL13870No training, Intrinsic damage in coil 1 d 5-7- 8 -9 LBNL17086 (4.5 K) e 5-7- 8 -9 LBNL17086 (4.5 K)Pre-load increased wrt HQ01-d e-2 5- 7 -8-9 CERN184 (2.2 K)85 (4.5 and 1.9 K)Tested at Cern HQM 0112FNAL 82 (4.6 K) 77 (2.2 K) Increased azimuthal space made for coil azimuthal expansion (5.4% / 4.6%) 0213FNAL 91 (4.6 K) 89 (2.2 K) The coil has one turn less in each layer Azimuthal space (7.6% / 6.3%) 0415FNAL 98 (4.6 K) 94 (2.2 K) Reduced coil compaction (new strand) Azimuthal space (6.8%/6.8%) RRP 54/61 RRP 108/127 Limiting coil is underlined

11. Next generation of HQ coils 11/14/2012HQ Coils: History & Performance11 Coil Number 1234567891011121314151617181920212223242526 RRP 54/61 RRP 108/127RRP 54/61Ti RRP 54/61 RRP 108/127 (Ta doped) Ti 108/127 (Ta) (Ta)????? 0.8 mm diameter strand0.778 mm diameter strand Delivery January 2013 Delivery mid-March 2013 Delivery may 2013 Delivery July 2013 ?? No axial pole gap 0.76 mm axial pole gap3.2-3.3 mm axial pole gap Cable without a coreCable with stainless steel core Original ends designRevised end design Cable fabrication  annealing (200ºC)  re- rolling (2 pass cable) Wire annealed (185ºC)  cable fabrication (1 pass cable) All the parts (end saddles, poles pieces, spacers, are left uncoated End saddles are coated with AlO3 All the parts are fully coated (10 mils / 254 um) HQ01HQ02 HQ03 Goal: to have a consistent set of coils for HQ03 and to have LHQ coils consistent with HQ03 coils

12. Summary 11/14/2012HQ Coils: History & Performance12 The pole gap in the coils allowing longitudinal contraction seems optimized (~3.2 mm) o The issue of coil 17 (pole gap which did not close) seems to be related to a mistake made during winding Next generation of HQ coils (starting from coil 21) will implement most of the features of HQ02 coils. In additon they will have: o All the part fully coated with 10 mils of ALO3 coating o The coil will be made in a consistent way (the goal is to have all the coils identical) o We are putting effort in order to get fabrication constitency between HQ and LHQ coils We are constantly trying to improve the coil fabrication process: o Constant evolution of the coil fabrication travelers (tight collaboration between BNL, LBL and FNAL) o Upgrading and improving the winding tooling (thigh collaboration with FNAL) Are the radial and azimuthal room left for expansion suitable? There are still unanswered question regarding the coating of the coil parts: o Acceptable tolerance for the coating thickness to ensure good field quality? o Unkown regarding the coating to coil interface. Cable mechanically unstable: o Second generation cable is less mechanically stable – several possible causes, need to understand also also in support of QXF cable

13. Back Up Slide 1 11/14/2012HQ Coils: History & Performance13  Coil 17 : a mistake made during winding?

14. Back up slides: Presentation made by H. Felice at the 1 st HiLumi collaboration meeting

15. HQ01 series Overview 11/16/201115H. Felice - 1st HiLumi/ LARP Collaboration Meeting HQ01aHQ01bHQ01cHQ01dHQ01e Coils Test 1-2-3-4 April 2010 1- 4 -5-6 June 2010 1 -5-7-8 Oct. 2010 5-7-8-9 April 2011 5-7-8-9 July 2011 HQ01a – 157 T/m – 79 % I ss – unusual ramp-rate HQ01b – 153 T/m – 77 % I ss – electrical failure HQ01c – 138 T/m – 70 % I ss – unusual ramp-rate HQ01d – 170 T/m – 86 % I ss - mechanical limit HQ01e – 170 T/m – 86 % I ss  9 coils (54/61 or 108/127 RRP)  5 tests at 4.4 K at LBNL

16. Overview of HQ01 coil fabrication 11/16/2011 H. Felice - 1st HiLumi/ LARP Collaboration Meeting 16 CoilStrandCableCoreMagnetNote 154/61992RNoHQ01 a-b-c (LBL)Limiting coil 254/61992RNoHQ01 a (LBL)Electrical failure 3108/127991RNoHQ01 a (LBL)Limiting coil 4108/1271000RNoHQ01 a-b (LBL) 5108/1271000RNoHQ01 b-c-d-e (LBL) 6108/1271000RNoHQ01 b (LBL)Electrical failure 7108/1271000RNoHQ01 c-d-e (LBL) 854/61996RNoHQ01 c-d-e (LBL) 954/61996RNoHQ01 d-e (LBL) 1054/61996RNoNot impregnatedBroken strands 11108/127 (Ti)1010RNoNot tested 1254/611012 SS - 25  m HQM01 FNALSpecial coil 1354/611008NoHQM02 FNALSpecial coil

17. HQ01b Electrical breakdown possible causes 11/16/201117 H. Felice - 1st HiLumi/ LARP Collaboration Meeting Extensive mechanical analysis performed  ruled out the participation of the support structure Autopsy of coil #6  revealed origin of the short in the interlayer  pointed out end design weakness both Lead end and Return end Review of the coil fabrication process: high compaction Combination of these effects => electrical failure in HQ01b Lead end View of the return end

18. High compaction: a common symptom of HQ01 coils 11/16/2011 H. Felice - 1st HiLumi/ LARP Collaboration Meeting 18 9 coils tested in HQ01 : same observations during fabrication  very high compaction after reaction  tendency to spring out of the reaction fixture (unlike TQ/LQ) Broken strands in coil 10 observed post-reaction Coil 3 Coil 7 Coil 10 Some corrective actions taken to reduce the compaction  reduction of the radial build-up of material in the cavity Coil / cavity size mismatch post reaction? Nb 3 Sn formation? Not seen in TQ/LQ

19. Dimensional changes during heat treatment Study on unconfined cables Study on sections of LQ - TQ and HQ coils Thickness LQ and TQ: 5.6 and 6% of increase HQ: only 1 to 2 % of increase Width LQ and TQ => 1 to 2 % of increase HQ => 1 % of increase Meas. Performed at FNAL D. Bocian, M. Bossert 11/16/201119 H. Felice - 1st HiLumi/ LARP Collaboration Meeting width Meas. performed at LBNL by J. Krishnan  axial contraction: 0.1 to 0.3 %  thickness increase: 1.4 to 4 %  width increase: 1.5 to 2 %

20. What is different in HQ? 11/16/201120 H. Felice - 1st HiLumi/ LARP Collaboration Meeting Comparison of the coil fabrication tooling between TQ/LQ and HQ  consistency with a constant cavity size at each step of the fabrication Comparison of the coil cross-sections  difference in the nominal design insulation  125  m in LQ  100  m in HQ Creating a buffer of 80  m per turn in LQ ~ 6% of LQ cable thickness Creating a buffer of 30  m per turn in HQ ~ 2% of HQ cable thickness Effective insulation: 86  m thick More room in the cavity required for radial and azimuthal expansion

21. Accounting for axial dimensional changes 11/16/201121 H. Felice - 1st HiLumi/ LARP Collaboration Meeting Axial tension in the conductor ~ 5MPa => Relaxation due to winding tension Contraction during reaction Axial gaps in the pole pieces during winding Axial contraction due to reaction estimated to be 2 to 3 mm/m Total gap size 3 to 4 mm/m Winding relaxation estimated to 1mm/m Stress (MPa) Modulus (MPa) Measured by Brett Collins Young modulus measured on various HQ unreacted cables:

22. Test Coils 11/16/201122 H. Felice - 1st HiLumi/ LARP Collaboration Meeting Coil 12 – 54/61 – cored cable By adjusting mid-plane shimming  ~3 % per turn of additional space Assembled and tested in FNAL HQM01  Limited by mid-plane turn  Improved performance at 150 A/s => 82 % Iss “Compaction theory” tested with test coils Increase of the azimuthal space in the cavity Still radial compaction Unusual coil size => FNAL mirror test Rodger Bossert & Guram Chlachidze Coil 13 – 54/61 – no core By removing the mid-plane turn in both layers  ~5 % per turn of additional space  Axial gap increased from 0.8 mm to 2 mm  closed after reaction  contraction of ~ 3mm/m Assembled in HQM02 tested at FNAL  91 % of Iss at 4.6 K  89 % of Iss at 2.2 K

23. HQ02 coils: reduced compaction 11/16/201123 H. Felice - 1st HiLumi/ LARP Collaboration Meeting A new series of HQ magnets: HQ02 Main requirement: using the same tooling as HQ01 Interlayer insulation increased to 500  m Accounting for dimensional changes and interlayer insulation  Smaller cable with smaller strand => 0.778 mm => 14.8 mm x 1.375 mm  Axial gap size 4 mm/m All coils made with 108/127 conductor Revision of the end parts design New approach for the magnetic cross-section  Reacted cable dimension based on some assumptions on cable dimensional changes  Conductor alignment on the OD of the pole piece

24. Overview of HQ02 coil fabrication 11/16/201124 H. Felice - 1st HiLumi/ LARP Collaboration Meeting CoilStrandCableCoreStatusMagnet 14108/1271017NoCompletedTo be tested in mirror 15108/1271020B SS / 8 mm / 25  m Wound & curedTo be tested in mirror / HQ02 16108/1271020D SS / 8 mm / 25  m To be tested in HQ02 Coil 14 post-reaction: limited protrusion ~1.5 / 2 mm Total axial contraction: 3.5 mm/m Gap: ~4 mm/m 0.5 mm/m post curing Coil 15 post-curing: Total axial contraction: NA Gap: 4 mm/m 1 mm/m post curing Ongoing cored cable measurement to get reference numbers for cored cable dimensional changes

25. HQ persisting electrical weaknesses CoilCoil to islandCoil to endshoeIL endshoe to OL endshoeMagnet 5 LE – 290 VHQ01 b-c-d-e 7 12.5 k  LE 700-800 VLE – high leakage currentHQ01 c-d-e 8 RE – 7.6 k  HQ01 c-d-e 9 RE - 340 VHQ01 d-e 11 Not tested 12 20 k  LE 700-900 V LE – 500 M  HQM01 13Dead short HQM02 14 LE IL(35 V) / OL (0.5  ) LE – 35 VNot tested Despite increased interlayer insulation Despite outer layer end-shoe revision Despite reduced compaction  Task force set up to address this issue  Possible revision in HQ and LHQ 11/16/201125 H. Felice - 1st HiLumi/ LARP Collaboration Meeting

26. Damaged insulation post-reaction 11/16/201126 H. Felice - 1st HiLumi/ LARP Collaboration Meeting Insulation fragmentation after reaction Possibly caused by the use of CTD binder Decision to stop using “precured” glass or Nextel ceramic for the interlayer insulation in the new generation of coils S-glass placed on the OD of the coil during reaction (combination of the brittleness and high compaction) Nextel ceramic interlayer insulation, not treated with binder

27. Summary 11 coils fabricated with the HQ01 design  Observations: coil high compaction, electrical breakdown, somewhat limited performance  Possible cause of limitations  initial coil design – fabrication process: high compaction 2 test coils with reduced compaction tested in FNAL mirror HQ02 design implemented in coils 14 and 15  108/127 conductor, smaller cable, OL end-shoe revision  Introduction of SS cored cable in all coils starting with coil 15 11/16/201127 H. Felice - 1st HiLumi/ LARP Collaboration Meeting

28. Some open questions Electrical weaknesses observed in almost all the coils  Failure of the hipot coil to metallic components Some insulation issues – compatibility with binder Some uncertainties about the coil dimensional changes Need to understand if the HQ somewhat limited performance come only from the coil high compaction  urgency to get HQ02 coils ready for test Ongoing investigation  Dimensional changes in cored cables  Task force for end-shoe redesign and improvement 11/16/201128 H. Felice - 1st HiLumi/ LARP Collaboration Meeting