Critical Current Characterization under Pure Bending Strains of Prebent Cu-Nb/Nb3Sn Strands for Practical React-and-Wind Process

M. Sugimoto, H. Tsubouchi, S. Endoh, A. Takagi, K. Katayama, K. Watanabe, S. Awaji, H. Oguro

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Nb-rod-method Cu-Nb reinforced Nb3Sn (Cu-Nb/Nb3Sn) wires have been successfully developed for commercialization of the react-and-wind (RW) processed Nb3Sn coils. Superconducting performance of the Cu-Nb/Nb3Sn wires is improved by applying the prebending treatment at room temperature, because of releasing the residual stress of Nb3Sn filaments (prebending strain effects). The purpose of this study is to confirm the efficient use of the prebending strain effects for optimizing critical current (Ic) characteristics under pure bending strain on the RW coil design. The Cu-Nb/Nb3Sn strands of 0.8-mm diameter were heat treated at 670 °C for 96 h on stainless steel grooved cylindrical holders of different radii of 10.1-32.1 mm. After half of the reacted strands were applied repeating prebending strain of ±0.5%, each of the prebent strands and the as-reacted (without prebending) strands was transferred to a Ti-6Al-4V alloy grooved cylindrical holder of 15.6-mm radius. Then, those Ic measurements were carried out under applied pure bending strains ranging from-0.9% to +0.84% at 11-17 T, 4.2 K. As a result, the prebent strand showed no deterioration of Ic in the applied pure bending strain ranging from-0.5% to +0.5% and had larger Ic than that of the as-reacted strand at no pure bending strain. In this paper, the Ic enhancements of the prebent Cu-Nb/Nb3Sn strands under pure bending strains are analyzed by using the Ic characteristics under axial strains.

Original languageEnglish
Article number7405316
JournalIEEE Transactions on Applied Superconductivity
Volume26
Issue number3
DOIs
Publication statusPublished - 2016 Apr

Keywords

  • Bronze-processed NbSn wire
  • Nb-rod-method Cu-Nb
  • Pure-bending strain
  • React-and-Wind
  • pre-bending effect

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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