Helene Felice 11/16/2011 LARP Collaboration Meeting 17 1 st HiLumi Collaboration Meeting CERN Status on HQ Coil Design and Fabrication

HQ01 series Overview 11/16/20112H. Felice - 1st HiLumi/ LARP Collaboration Meeting HQ01aHQ01bHQ01cHQ01dHQ01e Coils Test April June Oct April 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

Overview of HQ01 coil fabrication 11/16/2011H. Felice - 1st HiLumi/ LARP Collaboration Meeting3 CoilStrandCableCoreMagnetNote 154/61992RNoHQ01 a-b-c (LBL)Limiting coil 254/61992RNoHQ01 a (LBL)Electrical failure 3108/127991RNoHQ01 a (LBL)Limiting coil 4108/ RNoHQ01 a-b (LBL) 5108/ RNoHQ01 b-c-d-e (LBL) 6108/ RNoHQ01 b (LBL)Electrical failure 7108/ RNoHQ01 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/ SS - 25  m HQM01 FNALSpecial coil 1354/611008NoHQM02 FNALSpecial coil

HQ01b Electrical breakdown possible causes 11/16/20114H. 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

High compaction: a common symptom of HQ01 coils 11/16/2011H. Felice - 1st HiLumi/ LARP Collaboration Meeting5 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

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 11/16/20116H. 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 %

What is different in HQ? 11/16/20117H. 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

Accounting for axial dimensional changes 11/16/20118H. 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:

Test Coils 11/16/20119H. 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

HQ02 coils: reduced compaction 11/16/201110H. 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 => mm => 14.8 mm x 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

Overview of HQ02 coil fabrication 11/16/201111H. Felice - 1st HiLumi/ LARP Collaboration Meeting CoilStrandCableCoreStatusMagnet 14108/ NoCompletedTo be tested in mirror 15108/ B SS / 8 mm / 25  m Wound & curedTo be tested in mirror / HQ / D 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

HQ persisting electrical weaknesses CoilCoil to islandCoil to endshoeIL endshoe to OL endshoeMagnet 5 LE – 290 VHQ01 b-c-d-e k  LE VLE – high leakage currentHQ01 c-d-e 8 RE – 7.6 k  HQ01 c-d-e 9 RE VHQ01 d-e 11 Not tested k  LE 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 11/16/201112H. Felice - 1st HiLumi/ LARP Collaboration Meeting

Damaged insulation post-reaction 11/16/201113H. 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

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 11/16/201114H. Felice - 1st HiLumi/ LARP Collaboration Meeting

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 11/16/201115H. Felice - 1st HiLumi/ LARP Collaboration Meeting