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This content will become publicly available on August 3, 2018

Title: A review and prospects for Nb 3Sn superconductor development

Nb 3Sn superconductors have significant applications in constructing high-field (> 10 T) magnets. This article briefly reviews development of Nb 3Sn superconductor and proposes prospects for further improvement. It is shown that significant improvement of critical current density (J c) is needed for future accelerator magnets. After a brief review of the development of Nb 3Sn superconductors, the factors controlling J c are summarized and correlated with their microstructure and chemistry. The non-matrix J c of Nb 3Sn conductors is mainly determined by three factors: the fraction of current-carrying Nb 3Sn phase in the non-matrix area, the upper critical field B c2, and the flux-line pinning capacity. Then prospects to improve the three factors are discussed respectively. An analytic model was developed to show how the ratios of precursors determine the phase fractions after heat treatment, based on which it is predicted that the limit of current-carrying Nb 3Sn fraction in subelements is ~65%. Then, since B c2 is largely determined by the Nb 3Sn stoichiometry, a thermodynamic/kinetic theory was presented to show what essentially determines the Sn content of Nb 3Sn conductors. This theory explains the influences of Sn sources and Ti addition on stoichiometry and growth rate ofmore » Nb 3Sn layers. Next, to improve flux pinning, previous efforts in this community to introduce additional pinning centers (APC) to Nb 3Sn wires are reviewed, and an internal oxidation technique is described. Lastly, prospects for further improvement of non-matrix J c of Nb 3Sn conductors are discussed, and it is seen that the only opportunity for further significantly improving J c lies in improving the flux pinning.« less
Authors:
 [1]
  1. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Publication Date:
Report Number(s):
arXiv:1706.10253; FERMILAB-PUB-17-086-TD
Journal ID: ISSN 0953-2048; 1608205
Grant/Contract Number:
AC02-07CH11359
Type:
Accepted Manuscript
Journal Name:
Superconductor Science and Technology
Additional Journal Information:
Journal Volume: 30; Journal Issue: 9; Journal ID: ISSN 0953-2048
Publisher:
IOP Publishing
Research Org:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Nb3Sn; critical current density Jc; stoichiometry; area fraction; flux pinning; APC
OSTI Identifier:
1409076