Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh1 Conductor R&D Plan Arup K. Ghosh BNL

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh2 Introduction The first TQ magnets, TQC01 and TQS01 and SQ-02 use –0.7mm Modified Jelly-Roll strands “borrowed” from FNAL’s inventory 27-strand cable with 1.0 Deg keystone angle Strand is of the 54/61 design with large effective filament diameter ~  m Using “Nominal” heat treatment  Jc > 2000 A/mm 2 but the strand has a low stability current Is We now understand that Is in unstable strands is strongly influenced by “dynamic” effects –Improve thermal environment  Increase RRR of stabilizing copper –Achieve this by preventing excessive reaction of Nb- barrier –Optimize Reaction Time/Temp to increase the stability current to be well above magnet operating current

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh3 Heat-Treat Optimization J c (12T-15T) RRR B c2 HT-Temp 635C-695C & Time Higher Bc2 at higher T Strand Stability for large D eff

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh4 Ic and Is of virgin and of Strands Extracted from LARP Proto-type Cables

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh5 Commercial sources of high Jc Nb 3 Sn With the exception of ShapeMetal Innovation, Netherlands, (SMI), which uses Powder-in-tube technology (PIT) and has delivered strand to FNAL in the past, there is only one reliable source of high-Jc strand in the US. Oxford Superconducting Technology (OST) –MJR Conductor has been phased out –Present technique is RRP (Rod-Restack Process) Uses a distributed barrier approach Jc (12T) ~ 3000 A/mm 2 Effective Filament Diameter D eff ~ Sub-element Diameter –D eff scales inversely with increasing number of Sub-elements

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh6 RRP strand Long-lead item ~ 6-9 months after placing order SC vendor planning ~12-13 months Under the direction of the Conductor Development Program, OST has developed strands with increasing number of sub-elements to reduce D eff Billet /61 Billet /127 Billet /91

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh7 RRP Strand for LARP –OST has the most experience in fabricating strands of 54/61-stack design. This is considered a “production” wire used in the NMR business –Very limited experience with the 91 or the 127 stack design. These billets are presently considered by OST to be R&D billets. For FY06 LARP would like to use strands with the 84/91- stack design Why? Why not use the “production” 54/61 strand ? –Stability will improve with decreasing sub-element diameter Question is how to move from R&D to “production” at OST

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh8 Nb 3 Sn Strand Specification 84/91 Design

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh9 Nb 3 Sn Strand Specification 54/61 Design

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh10 Conductor Development Program CDP has been the main driver in OST’s high-Jc strand R&D. –It continues to fund this development in FY06 –Main Goals  reduce Deff, billet “scale-up”, (NbTi) 3 Sn LARP can take advantage of the strand that is in the CDP inventory to conduct strand characterization for use in TQ-type cable LARP can also “borrow” from the CDP inventory At present OST is fabricating strand for CDP that is similar to strand being considered for LARP purchase

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh11 CDP-R&D Inventory Compiled with D.R Dietderich Yield of billet 8502 is ~ 50% due to wire breakage Billet 8521 is in process, yield not known

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh12 Comments 30 kg can be fabricated into 5 UL’s each 65m long. Each UL is for a TQ- coil With the exception of billet 8079, all the strand in CDP inventory is the high Sn-content capable of a Jc of 3000 A/mm2. The most recent billet 8220 (54/61-design) has this Jc and a RRR ~ 200. With this RRR the stability current is ~ A. Most of the RRP strand at 0.7mm have yet to be cabled as a TQ-cable with 1.0 deg keystone. LBL has recently made a short (17m) trial piece of 27-strand TQ cable using strand from This is being evaluated for Ic, Is and RRR. A short length ~ 4m of cable has also been fabricated using strand from 8079 (90/91-design), this too is under evaluation. Strands from this billet show stability currents > 1200A. For strands with either the 61, 91 or 127 stack, the key parameter that ensures a high stability current is the RRR of the copper stabilizer. –Provided the copper remains clean, strand stability increases as the stack number is increased i.e. sub-element size is decreased

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh13 Recent OST Billets

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh14 Target Program

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh15 Total Conductor Estimate Total Total 936 kg Plan for 1100 kg

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh16 Procurement Plan 1100 kg FY kg 85 kg FNAL 95 kg 3/31/06 Plan A 54/61 Plan B 84/91 60 kg 7/31/06 60 kg 10/31/06 FY kg FY kg Low- Risk Low Risk Higher Risk

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh17 Procurement Strategy CDP has two billets on order which uses the same sub-element with the potential for Jc(12T) ~ 3000 A/mm 2 –One uses 54/61 design –The other 84/91 design –Delivery 11/31/05 CDP is also placing an order for 90 kg for high Jc wire using the 84/91 designDelivery 3/31/06 LARP will place an initial order for 95 kg (this is the yield from one sub-element extrusion billet) –54/61 designDelivery 3/31/06 This allows for material to be in the pipeline that we are certain to have in hand for the magnets being fabricated in FY06. If the 84/91 billets for CDP are successful then LARP could “swap” that with the 54/61 wire delivered under its order

Collaboration Mtg, St Charles, IL 10/5-6, 2005 A. Ghosh18 Summary Present Status –Draft specification sent to OST –Wire from Billet 8502 (84/91) arriving LBL 10/10/30 –This wire needs to be characterized for Ic, Is and RRR –Cable using billet 8220 (54/61) under investigation LARP order needs to be placed soon