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WBS 2.4.2 STRAND PROCUREMENT

WBS 2.4.2 STRAND PROCUREMENT. Arup K. Ghosh BNL. Outline. Present status of strand procurement Future strand for LARP Smaller Filament D eff PIT strand Tolerance of RRP conductors to cabling degradation Filament Spacing Rolled strand Revisit strand specification.

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WBS 2.4.2 STRAND PROCUREMENT

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  1. WBS 2.4.2 STRAND PROCUREMENT Arup K. Ghosh BNL

  2. Outline • Present status of strand procurement • Future strand for LARP • Smaller Filament Deff • PIT strand • Tolerance of RRP conductors to cabling degradation • Filament Spacing • Rolled strand • Revisit strand specification

  3. Procurement PlanNov-05

  4. Nb3Sn Strand SpecificationRRP-54/61 Spec. No.: LARP-MAG-M-8001-RevB

  5. Procurement Status3-30-06

  6. Strand Purchase and Inventory as of 4-20-06

  7. RRP 54/61 –Piece Length • 250 kg of wire produced for LARP and CDP in the last 12 months, single billet yield is ~ 35kg • 93 % in lengths >1Km, 57% in lengths >3 km • With the following HT 665C/50 hrs • Average Jc(12T)=2880 A/mm2 • Average RRR= 189

  8. Procurement Plan For FY07 3-30-06

  9. Projected Inventory

  10. Towards a more “flux-jump” stable conductor • Why ? • Intrinsic (Adiabatic) stability of wire • Field quality in magnets • Reduce Effective Filament Diameter Deff • Deff< 30 mm (adiabatic limit not established experimentally for high Jc wire ) • For Deff > 35 mm, maintain high RRR after reaction  prevent Sn-leakage • OST-RRP- 91 and 127 sun-element billet design • Cabling Effects • Shearing of sub-elements RRR degradation • SMI-PIT- 288 • 50 mm at 1.25 mm wire • 32 mm at 0.8 mm wire

  11. Decreasing the sub-element size • Pack increasing number of sub-elements into Re-stack • Increasing number of bundles  packing more difficult • More cold work increases the hardness of non-Sn parts • Additional Cu-Cu surfaces  worse bonding  yield ?

  12. 91-127-217 series made with Nb-Ta for CDP R&D • High Jc design (3000 A/mm2): • Objective was to only vary the sub-element size • same sub element billet for all restacks • all restacks ~53% non-Cu, 0.7 mm strand • Significant wire breakage for all, 217-stack the worst • For a reaction at 665 C/50hrs (Jc, RRR) • 91-stack 2920, 134 • 127-stack 2720, 110 • 217-stack 2660, 7 (Many broken barriers) • Suggests there is some size effect controlling the maximum Jc

  13. Future RRP Strand • Is OST ready to produce 91 and 127 sub-element billets ? “Further to our discussions today about 61  127 stack designs for LARP, this year we are producing 91-stack material for the EFDA dipole. The sub-element design is for lower Jc and uses Nb-Ti (Jc ~2400 @ 12 T), but the work will give us some yield data on our way to 127 stacks.” Based on CDP R&D billet 8079 (90/91) and FNAL billet 8195 (108/127) both of which uses the same sub-elements of Nb/Nb-47Ti

  14. EFDA Dipole Project E. Salpietro Strand based on 90/91-stack design using Nb/ Nb-47Ti rods Due dates Delivery One (30 kg strand): delivered Delivery Two (120 kg strand): 9 months Delivery Three (280 kg strand): 15 months

  15. Future RRP Strand • Is OST ready to produce 91 and 127 sub-element billets ? • At present the lower Jc ( > 2000 A/mm2) 91-design billet is moving into production  EFDA Order of 400 kg • Under CDP R&D this year, a high Jc 108/127 billet is being processed (Nov-06) • FNAL has OST fabricating a R&D billet using 120/127 design (Dec-06)

  16. Powder-in-Tube (NbTa)3Sn (PIT)Shape Metal Innovation (SMI) J. Lindenhovious B179

  17. PIT -Strand Luc Oberli (CERN) WAMDO-06 • NED is pushing SMI-VAC to develop strand. • Latest billet B207 is 288 filament, similar to B179 • Strand Diameter 1.25 mm • Cu/Non-Cu= 0.96 • Jc > 2400 A/mm2 At 12 T B179 B 207

  18. SMI – 288 filament Luc Oberli (CERN) WAMDO-06 Jc = 2077 A/mm2 at 12 T Jc = 1118 A/mm2 at 15 T HT = 84 hours at 675 0C Jc non Cu lower than B179 by ~ 10 - 15 % due to powder preparation which underwent by mistake an additional HT. • Stability measurements performed by LASA : Field rate ~ 15 mT/s • At 1591 A, no quench in the field range : 0 - 5 T

  19. SMI-PIT B-207 Wire drawn to 0.8 mm Jc(12T) : 2145 A/mm2 , Js > 4500 A/mm2 (Is >1200A) Filament size : 32 mm (No flux-jump observed in magnetization)

  20. Cabling Degradation • Strand Deformation at the cable edges • Filament Distortion • Simulate by rolling strands • E. Barzi (FNAL) • Filament Merging • Microscopy, Ic and Is measurements

  21. Rolled Strands RRP 54/61 Def=28% Def=14%

  22. SMI : Strand deformation by rolling Luc Oberli (CERN) WAMDO-06 B 179 B 201 Deformation of 25 %, i.e. d0 - t = 0.25 mm. “Distribution of Cu within the strand important in order the strand can sustain heavy mechanical deformation as in cabling.”

  23. SMI – Deformation by rolling on B207 Luc Oberli (CERN) WAMDO-06 Ic Degradation of 15 – 17 % on samples with a deformation level of 28% RRR value dropped to 80 indicating Sn diffusion in the Cu matrix Def = 28 % No HT Def = 28 % after 84 h at 675 0C With HT 2.8 at. % Sn

  24. Re-visit Strand Specification

  25. Summary • There is sufficient RRP 54/61 strand for the magnets in the near term • 91-filament is moving into production • 127 filament can be in production within 12 months. • PIT strand with 288 filaments is “flux-jump” stable at 0.8 mm wire diameter with Jc ~ 2100 A/mm2 at 12 T • Cabling Degradation from filament shearing • Optimization of cabling parameters • Optimization of strand design • Increase filament spacing ? (FNAL has already ordered a 60/61 billet with larger Cu-spacing, evaluation in progress)

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