Compressive Prestrain in High-Niobium-Fraction Nb3Sn Superconductors

Published

June 1, 2005

Author(s)

John (Jack) W. Ekin, Najib Cheggour, Mike Abrecht, Cameron C. Clickner, Michael Field, Seungok Hong, Jeffrey Parrell, Y. Zhang

Abstract

Multifilamentary Nb₃Sn superconducting strands fabricated with high niobium fractions have exceptionally high critical-current densities but are sometimes marginally stable during testing. We report a technique for determining the pre-strain in such conductors, in which additional stabilizing copper is electroplated onto the conductor and the pre-strain is determined by extrapolation to the as-fabricated niobium fraction. This technique is used to measure the pre-strain in conductors with high niobium fractions of 20% to 30%. Values of the pre-strain, ε_max in these conductors are reduced to the range 0.1% to 0.2%, which is significantly less than the ε_max values of 0.2% to 0.4% in traditional bronze-process Nb₃Sn conductors (where niobium fractions are typically about 10% to 15%). However, including about 20% dispersion-strengthened copper into the conductor matrix restores ε_max to the range 0.25% to 0.35%, thus providing practical levels of ε_max for magnet design in high-niobium-fraction strands.

Citation

IEEE Transactions on Applied Superconductivity

Volume

15

Issue

2

Pub Type

Journals

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Keywords

axial strain, copper-alloy, critical current, niobium-tin, thermal contraction

Citation

Ekin, J. , Cheggour, N. , Abrecht, M. , Clickner, C. , Field, M. , Hong, S. , Parrell, J. and Zhang, Y. (2005), Compressive Prestrain in High-Niobium-Fraction Nb₃Sn Superconductors, IEEE Transactions on Applied Superconductivity, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=31825 (Accessed October 10, 2025)