Nb3Sn Cable and Insulation for LARP High-Gradient Quadrupole Magnets US LHC Accelerator Research Program bnl - fnal- lbnl - slac Nb3Sn Cable and Insulation for LARP High-Gradient Quadrupole Magnets D.R. Dietderich Lawrence Berkeley National Laboratory

Outline of the Presentation Cabling Philosophy for Rutherford Cables 1 Pass and 2 Pass cables Cored cables R&D to reduce HQ cable dimensions With wire diameters of 0.778 mm and 0.800 mm Insulation development LARP TQ cable Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

LARP Cable Fabrication – 2 Pass 2 pass process was developed to reduce dimensional changes of a cable during coil processing and reaction A cable is fabricated oversize in thickness, annealed (200C for 2-4 hrs), and re-rolling to final thickness. The anneal reduces the residual stress in the cable and the cable typically shortens by 0.20 – 0.25%. Very important -- Cable is permitted to get wider during the second pass – 2nd pass roll are~ 50-100 microns wider If a cable is too narrow -- Strain localized to 3 strands at the edge of a cable due to friction between rolls and strand Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

LARP Cable Fabrication – 1 Pass 1 pass process has been developed for adding stainless steel (SS) cores to cables Strand is annealed (190C for 4 hrs) prior to cabling Cable is made in 1 pass to final dimensions Due to mechanical differences between the strand and the SS core a 2 pass process is not possible. However, other core materials such as S-glass tape or MgO paper tape could be made in 2-pass. Un-reacted Reacted wire Ductility check Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

2 Pass Cable with MgO Paper & S-glass Cores Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

Cored Cables (HQ-1012) Used in HQ Coil 12 HQ cable 1012 (old cable parameters) 35 strands with diameter of 0.80 mm 1.44 mm mid-thickness, Did not increase mid-thickness with of core addition 15.1 mm wide 0.75 deg. Keystone angle 8 mm wide, 0.025 mm thick stainless steel core Biased to thick edge of cable Core biased toward thick edge of the cable No fabrication issue with the addition of a SS core Addition of the core did not degrade the Ic Measurements show a reduction of 3-5 % which is typical for an HQ cable without a core Mandrel with slot for adding a core Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

Objective of Cable R&D To permit the use of existing HQ tooling The cable dimensions needed to be reduced to: Provide more space azimuthally (i.e. thinner cable) Provide more radial space (i.e. narrower cable) Cable R&D targets dimensions: Reduce HQ cable thickness by 65-100 microns To 1.375 mm - 1.340mm Width target is < 15mm (14.7mm -15mm) Accommodates dimensional changes of cable during reaction Thicker insulation or more insulation between layers and tooling Keystone angle un-changed at 0.75 deg. Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

HQ Cable R&D to Reduce Cable Size The next slide shows the thickness and width of several cable samples Cable 1014 34 strands with a diameter of 0.80 mm Cable 1015 35 strands with a diameter of 0.778 mm “Blue Box” denotes the target parameters needed to accommodate the cable dimensional changes in the present tooling. The box with dashed lines are the parameters deduced from R&D on TQ and LQ coils “Red Circle” denotes the new HQ parameters with the 0.778 mm diameter strand Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

HQ Cable Parameters of R&D Cables TQ LQ Old HQ cable HQ Box New HQ cable Zone with Too much damage Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

Critical Current Cable 1014 with 34 strands and wire diameter 0.80 mm Un-deformed Round Wire Extracted Strands Gosh (BNL) A. Godeke (LBNL) Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

RRR 1014 – 0.80 mm wire Un-deformed Round Wire Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

Critical Current Cable 1015 & 1017 with 35 strands and wire diameter 0 Critical Current Cable 1015 & 1017 with 35 strands and wire diameter 0.778 mm 36 strands Un-deformed Round Wire 1st Production cable 1017 Extracted strands Un-deformed round wire 665C for 48h 650C for 72h Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

RRR 1015 – 0.778 mm wire Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

Cable 1015 Sections I & L 1015-L 1015-I No significant sub-element damage is observed in the wire cross-sectional images Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

Cable -- Summary A stainless steel core can be added to the standard HQ cable without significant loss of critical current Standard HQ cable with 0.80 mm diameter wire could have be decreased in thickness and width to meet the target parameters (HQ box) However, the risk of damaging to the strand was considered to great with addition of a corfe – i.e. reduced processing margin. New HQ cable uses a 0.778 mm diameter strand to achieve the new cable parameter The critical current variation in cable 1015 is not understood but could be due to: Sample handling while preparing for Jc testing. Or localized damage in some strands during cabling. Suggests that a cable testing facility is needed for accurate cable critical current measurements. RRR was reduced slightly by cabling Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

Insulation Braided onto Cables New England Wire S-glass with 636 sizing TQ/LQ Cable 10 mm wide Braid angle 64 deg. New England Wire S-glass with 933 sizing HQ Cable 15 mm wide Braid angle 55, 60, 64 deg. Pitch Angle Thickness 55o 0.103 mm 60o 0.109 mm 64o 0.114 mm A. Ghosh - BNL Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

Tape Winding LBNL having vendor fabricate tape winding machine Demo video FNAL has an established process with E-glass 2 layers Thickness ~0.100mm Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

Summary – Insulation Options Braided insulation onto cable – Primary option New England Wire S2-glass with 636 and 933 sizing – Requires cleaning of insulated cable thickness of 0.103-0.114 mm Plan to develop process for fibers with Silane sizing Revolution Composites S2-glass – Also makes sleeve New company but with staff from EDO Fiber Innovations Tape options – Second option E-glass 2 layers can produce 0.100 mm Contains boron – could be an issue. S2-glass tape Two layers of tape is > 0.100mm (0.125-0.150 mm) Consider making braided insulation thicker to match Consider single layer of tape 0.100 mm thick Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

Extra slides

R&D to Reduce HQ Cable Dimensions New cable parameters: Mid-thickness 1.375 mm from 1.44 mm Width 14.80 mm from 15.10 mm Keystone angle 0.75 deg. Unchanged New cable designs will provide more space in tool for cable dimensional changes Have made the first production cable 1017 with new parameters HQ coil 14 has been fabricated and is ready to test in a mirror. Have just made a cored cable with the new cable parameters with a strand diameter of 0.778mm. Coil winding with the cored cable was OK However, popped strands were produced going around the pole They are pushed back into position and winding continues Planning to cut HQ coil 12 into sections for inspection. Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN

1 Pass Cable with Stainless Steel Core Nov. 16, 2011 D.R. Dietderich Hi Lumi/LARP CM17 CERN