LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh1 LARP DOE Review July , 2009 FNAL 2.4 Materials – Conductor Support Arup K. Ghosh (BNL) BNL -FNAL - LBNL - SLAC Dan Dietderich (LBNL) Emanuela Barzi (FNAL)

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh2 Outline 1.Introduction 2.OST strand production 3.Cable Production and R&D 1.Extracted strand test 2.HQ-Cable R&D 4.Electro-mechanical studies – NIST 5.Instability in superfluid helium 6.Production Plan for FY09 and FY10 7.Inventory of strand 8.Summary

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh3 Nomenclature RRP ® Re-Stack Rod Process IcCritical current usually quoted at 12 T, 4.2 K, A JcCritical current density over the non-Cu area, A/mm 2 Is/JsLow-field Stability current/ current density, A/mm 2 dfilament diameter ~ sub-element diameter,  m RRRResidual Resistance Ratio of the Cu-matrix R(295K)/R(18K) IqQuench current, can be > = or < than Ic, A CVolumetric Heat Capacity, J/m 3 -K V-I Set field then ramp current till wire quenches V-HSet current at zero field then ramp field ULLength of cable required for a magnet coil  max applied strain for maximum Ic in Ic-strain measurements  irr applied strain when Ic degrades irreversibly

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh4 1. Introduction The first long quad-magnet LQS01 use RRP - 0.7mm strand  27-strand cable with 1.0 o keystone angle Strand is of the 54/61 design with d ~ 70  m and Jc >2400 A/mm 2 at 12T Flux-jump instability at low field d

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh5 d~ 70  m d~ 50  m Observed in Magnetization measurements  Persistent current collapses periodically at low fields

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh6 Magnetization Instability at Low Fields  Is V-H V-I IsIs 0.7 mm RRP 54/61 d ~ 70 µm J c (12T)~ 2700 A/mm 2 RRR ~ 5

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh7 Impact on LQ Magnet Performance LQ-Magnet with this Load-Line will Quench at 8T Un-Stable Stable

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh8 Low-field instability does not impact magnet performance Using an “optimized” heat treatment Extracted strands from LQ cable have –  Jc (12T,4.2K) is > 2400 A/mm 2, –RRR >100 –stability current I s >800A, well above magnet operating current I op 210C/72h + 400C/48h + 640C/48h For high Jc RRP ® 54/61 wires of 0.7 mm, flux-jumps are inevitable in low-field regions of magnets. Will “flux jump” initiate a quench as Magnet approaches I op of 500 A (per strand)? Not if: local copper stabilizer RRR is “high” > 100

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh9 2.OST Strand Production Oxford Superconducting Technology, OST High J c production wire Rod Re-Stack Process, RRP ® 54/61 Design “Baseline Strand”- Specs.

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh10 RRP 54/61 LARP Production Long lengths  sign of Excellent process control and Stable production. 17 Billets 650 kg of wire produced in the FY06-FY08, single billet yield is ~ 35kg (~10 km) 93 % in lengths >1Km, 73% in lengths >3 km, 29% >10 km

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh11 3.Cable Production LQ- Cable unit length (UL) is 225 m LQ Specifications: Same as TQ Cable Specifications Six unit lengths of LQ cable were made in FY08 and six more cabled in FY09

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh12 LQ- Cable Acceptance Optical Microscopy of cable React round and extracted strands using the following heat-treat schedule:  210 o C/72h o C/48h o C/48h Extracted strand measurements of Ic, Is and RRR – Check for Minimum Ic requirement – Check for strand stability

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh Ic(12T, 4.2K) of Extracted Strands I c-Min

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh14 Is of Strands Extracted from Cables I ss

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh15 Optical microscopy used to detect early cabling problems Acceptable Reject

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh16 LQ-Cable Production of 27-strand Keystone Cable at LBNL is very stable

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh17 3.2HQ 15 mm wide Cable Development Cabling degradation 8% HQ prototype Cable B0977R

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh18 HQ cable development 0% 17% 6% 2% Cabling degradation sensitive to cable width Mechanical stability sensitive to cable mid- thickness Cabling was done using several lots of RRP 0.8 mm wire 986 and 987 used 54/61 with standard Cu-spacing 991 used 108/127 with increased Cu-spacing 992 used 54/61 with increased Cu-spacing

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh19 Latest HQ cable parameters Strand Diameter 0.8mm No. Strands 35 Thickness 1.44 mm Width mm Keystone angle 0.75 o 5 unit lengths of HQ cable made from 54/61 strand 1 unit length made from 108/127 strand (4 additional unit lengths are scheduled for cabling) 210C/72h + 400C/48h + 665C/48h Jc > 2900 A/mm 2, RRR>100

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh20 4.Electro-mechanical Measurements of 0.7 mm RRP strand Collaboration with NIST Najib Cheggour

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh21 E L E C T R O M A G N E T I C S D I V I S I O N B O U L D E R, C O L O R A D O In tension, irreversible damage for 54/61 sets in at a strain just above  max. Loading Sample Unloading

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh22 In Tensile strain very little difference between 54/61 and 108/127  =  irr -  max (54/61)=0.04% (108/127)= 0.05%

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh23 E L E C T R O M A G N E T I C S D I V I S I O N B O U L D E R, C O L O R A D O In compression Ic is reversible-no permanent damage for both types of wire

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh24 5.Strand Stability at 1.9 K Erratic quenching and no increase in quench current of TQ02 magnets in superfluid helium –Detailed measurements of the quench performance of LARP strands in superfluid helium. –Measurements on round and extracted RRP 54/61 and 108/127 strands in 4.2 K pool-boiling helium and in sub- pressure superfluid helium at 2K –Besides the “flux-jump” instability mediated by collapsing persistent currents at low fields, –Strands also exhibit “Self-Field” Instability due to transport current. This is usually established by looking at the quench performance of strands in fixed external fields. V-I Measurements

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh25 Extracted Strand from LQ Cable, RRP 54/61, Jc ~ 2550 A/mm 2, (BNL data)  4.2 K  2.0 K LQ-Load lines Outer Inner

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh26 In superfluid, stability threshold lower than at 4.2 K  4.2 K  2.0 K

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh27 Comparison of 54/61 and 108/127 Extracted Strands at 4.2 K (FNAL Data) LQ-Load lines

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh28 Quench Currents at 1.9 K (FNAL data)

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh29 Strand Stability at 1.9 K Instability more pronounced in superfluid helium at 1.9 –2.1 K than at 4.2 K –At 4.2 K strand instability dominated by magnetization flux-jumps at low fields < 3T –At K, instability is dominated by “self-field” instability at intermediate fields of 5T – 9T. –Stability threshold is higher for the smaller sub-element strand (108/127). – Minimum quench currents of strand in liquid helium still higher than that observed in magnets

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh30 Cu-spacing between Sub-elements improves sub-element deformation under rolling Based on work at FNAL: Comparison of rolled strands from a standard 54/61 billet and a 60/61 billet with larger spacing Comparison of a 108/127 standard billet with a 114/127 billet with larger spacing FEM calculations both at FNAL and CERN show that sub-element deformation under rolling is reduced by increasing the Cu- spacing and having a large central Cu-core. Therefore we have increased the Cu- spacing in our recent orders –Wire has higher Cu content Sub-elements

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh31 Stability can be improved by reducing filament diameter, d –Smaller sub-elements can minimize flux jumps and improve stability. –Main driver has been DOE- HEP Conductor Development Program –And FNAL R&D Program Smaller Filament Size 70  m35  m

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh32 6.Wire Production Plan RRP 108/127 Strand for LARP In FY08 LARP looked at strands with the 127-stack design – High Jc ~ 3000 A/mm 2 has been achieved – 30% reduction in Ds  Stability improves with decreasing sub-element diameter – lower magnetization – Option to increase strand diameter  wider cable  OST delivered a fixed price contract for 180kg of 108/127 strand, S/d~0.13, 0.7mm, Nb-Ta-Sn  This production went well – good piece lengths  Cu fraction is 53% compared 47% in standard 54/61

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh33 Procurement Strategy Based on strand/cable characterization, we selected the 54/61 as the baseline strand for LQ. Accordingly, we followed a 54/61 procurement plan that covers the needs of LQ01, LQ02, spare coils, HQ models. Although the 54/61 strand is adequate for LQ and HQ, a conductor with smaller filament diameter would be better for any accelerator magnet RRP 108/127 with increased Cu-spacing is the most promising option. Our current plan allows us to further develop and qualify the 127-design strand and, to procure this strand consistently for use in magnets

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh34 Qualification of 127-design strand  Repeat Roll strand measurements using “127-strand optimized HT”  no surprises  Extracted strands from TQ cable (B0982R)using 108/127 strand  Very low Ic degradation and Is > 1200 A  Fabricate TQ coils from B0982R  TQS03 magnet test at CERN  underway  Extracted strands from HQ 15 mm wide cable with 0.75° keystone and using 0.8 mm strand  Low cabling degradation.  TQM03 mirror magnet test  Good performance at 4.2 K and at 1.9 K

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh35 Procurement – Planning for QA Strand Lead time is 12 months LARP 1310 kg FY kg 0.7 mm FY kg 54/ mm 200 kg 54/61 5/31/07, 9/31/ kg 108/127- RRP 02/28/08 FY kg 88 kg 54/61or 108/127 01/30/10 70 kg 54/61 or 108/127 4/31/10 FY kg QA FY’06 price $1063/ kg FY’09 price $1247/ kg 0.7 mm  295 m/kg 0.8 mm  225 m/kg

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh36 7.Conductor Inventory Status 26 kg required for UL of LQ –12 UL’s have been made –Present 54/ mm strand inventory is 78 kg 60 kg of 54/ mm wire from five billets available for practice coils 180 kg of RRP 108/127 (increased Cu-spacing) –37 kg at 0.7 mm  used to make TQS03 –117 kg at 0.8 mm  can be used to make 6 UL of HQ –24 kg at 1.00 mm 85 kg of 54/61 at 0.8 mm with increased Cu-spacing delivered in Dec’08  5 UL of HQ (1UL HQ = 18kg) 75 kg of similar wire TBD in Aug’09 and 88 kg of wire TBD in Jan’10 –Strand design 54/61 at 0.8 mm 70 kg order in process TBD in July’10

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh37 R&D to address stress-strain and stability issues for cable conductors in magnets Collaboration with NIST –Completed, deals only with longitudinal strain Cable tests –Effect of transverse pressure on Ic What is the tolerance of the cable in the magnet ? First series of tests done in May ‘09 (NHMFL, LBNL) –Commissioned 25 KA low noise SC-Transformer –Active strain gauge measurement –Test was limited by cable damage probably during assembly –Strand/Cable stability at 4.2K and 1.9K (FNAL, CERN) Bridging the understanding from strand to impregnated cable to magnet performance Samples have been reacted, being assembled in test fixture.Test at FRESCA facility (CERN) Sep’09

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh38 8.Summary LARP funded: The Materials Group has focused on strand procurement, cable production, strand and cable qualification, coil reaction schedules and witness sample testing CDP and core program funded: R&D towards developing the “next generation” conductor Conductor issues requiring more R&D is in –Transverse stress effects in cables –Instability in superfluid helium The 108/127-stack design has matured significantly at OST so that it is considered a “production” wire There is adequate inventory of 54/61 for LQ01/ LQ02 and HQ01 magnets Beyond the first LQ and the HQ magnets the 108/127 strand could be considered for these and for QA magnets

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh39 End of Presentation

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh40 Additional Slides 1.Cable Test at NHMFL 2.Strand inventory and usage

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh41 1.Cable Test at NHMFL New system at NHMFL: SC transformer & strain measurements

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh42 VI-results first sample

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh43 Displacement metering test Load test to 220 MPa Initial uneven loading with large jumps (friction / sticking?) More uniform loading above 75 MPa pressure and during unloading Uneven loading could require future automatic alignment features

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh44 Summary of Cable Test New superconducting transformer –Successfully commissioned –Less noise, cheaper and faster to operate, self-protecting New mechanical instrumentation –Successfully commissioned: Verifies local sample loads –Indicates asymmetric load issues that require correction Two samples tested –Both unsuccessful: 10.8 kA and 6 kA quenches, 16 kA expected –Sample preparation most probable cause and requires improvements To be continued…

LARP DOE Review July 13-14, 2009Materials – Conductor Support - A. Ghosh45 2.Strand inventory and Usage