Nb₃Sn Superconductors Made by an Economical Tubular Process

E. Gregory, M. Tomsic, X. Peng, M. D. Sumption and A. Ghosh

Abstract - The tubular technique for economical production of Nb3Sn material with large numbers of subelements is being explored further by Supergenics I LLC and Hyper Tech Research Inc. The number of subelements has been raised to 271 (246+25) by increasing the size at which the restacking is carried out. The product exhibited no fabrication problems and was drawn down and tested at a wire diameter of 0.42 mm, where the subelements are 18 µm in diameter. Heat treatment of a 271 subelement restack has been varied and a pre heat treatment of 48 h at 575 °C followed by long times at 635 °C has been shown to be advantageous. Restacks with 217 subelements have been subjected to both compositional and heat treatment changes and the best results, closely approaching those found on PIT materials, have been found on samples given 500 h at 625 °C.

Index Terms - Copper, Niobium, Tantalum, Tin, Tubular superconductors

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Manuscript received August 18th 2008. This work was supported in part by the U.S. Department of Energy under a Phase I SBIR Grant DE-FG02-07ER84860.
E. Gregory is with Supergenics I LLC, 336 Sterling Rd., Jefferson MA, 01522-1333 USA. (phone 508-829-9041: e-mail: ericgregory@charter.net).
M. Tomsic is with Hyper Tech Research Inc., 1275 Kinnear Rd., Columbus OH 43212-1155, USA. (phone 937-524-6297: fax 614-481-4080; e-mail: tomsic@voyager.net).
X. Peng is with Hyper Tech Research Inc., 1275 Kinnear Rd. Columbus OH 43212-1155, USA (phone 614-481-8050: fax 614-481-4080; e-mail: xpeng@hypertechresearch.com).
M.D. Sumption is with LASM, Ohio State University, Columbus OH, 43210 USA. (phone 614 688 3684: fax 614 688 3677; e-mail: sumption@matsceng.ohio-state.edu).
A. Ghosh is with Brookhaven National Laboratory, Upton, NY, 11973-5000, USA. (phone; 631-344-3974: fax 631-344-2190: e–mail: aghosh@bnl.gov).