Performance of Thin Cu-Nb/Nb3Sn Round Wires and Tapes Pre-Bent for R&W Process

• Published in: IEEE transactions on applied superconductivity Vol. 32; no. 4; pp. 1 - 6
• Main Authors: Sugimoto, Masahiro, Asami, Daisuke, Fukushima, Hiroyuki, Hirose, Kiyoshige, Kato, Tomoya, Tsubouchi, Hirokazu, Awaji, Satoshi
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aspect ratio; Bending; Coils; Compressive properties; Compressive strength; Copper; Critical current (superconductivity); Cu-Nb/Nb<named-content xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" content-type="math" xlink:type="simple"> <inline-formula> <tex-math notation="LaTeX"> _3</tex-math> </inline-formula> </named-content>Sn wire; Diameters; Diffusion barriers; Filaments; Heating systems; Integrated circuits; Nb-rod-method Cu-Nb; Niobium; pre-bending effect; react-and-wind; Spirals; Strain; Thickness; Windings; Wires
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2022.3151311

Cu-Nb/Nb 3 Sn wires have high mechanical strength and large compressive residual strain. In this study, we successfully developed thin Cu-Nb/Nb 3 Sn round wires and tapes to avoid the critical current ( I c ) degradation caused by damage of brittle Nb 3 Sn filaments in React-and-Wind (R&W) process with small bending diameters. Both the Cu-Nb/Nb 3 Sn round wires of 0.45 mm diameter and the tapes of 0.40 mm thickness had I c increase by pre-bending treatments up to bending strains of ±0.6% in the Nb 3 Sn filamentary area including the tin-diffusion barrier. The pre-bent tapes of thicknesses 0.9-0.25 mm (aspect ratio 1.5-10.2) showed higher I c characteristics than as-reacted tapes independently of magnetic field directions. The R&W spiral coils of 39 mm diameter, which were wound with the pre-bent round wire of 0.45 mm diameter and the pre-bent tape of 0.48 mm thickness, retained higher I c - B characteristics than those of the W&R spiral ones.