Applicability of React-and-Wind Method in JA-DEMO TF Conductors With Cu-Nb Reinforced $\text{Nb}_{3}\text{Sn}$ Strands

Abstract

$\text{Nb}_{3}\text{Sn}$ conductors for JA-DEMO-TF coils require both higher current capacity under larger electromagnetic stress and lower manufacturing costs than ITER-TF $\text{Nb}_{3}\text{Sn}$ conductors. Cu-Nb reinforced $\text{Nb}_{3}\text{Sn}$ (Cu-Nb/$\text{Nb}_{3}\text{Sn}$) strands produced by Nb rod method have superior mechanical strength properties at room temperature (RT) than conventional non-reinforced Cu/$\text{Nb}_{3}\text{Sn}$ strands, even after the $\text{Nb}_{3}\text{Sn}$ reaction heat-treatment. The React-and-Wind (R&W) processes not only minimize the compressive residual strain of the $\text{Nb}_{3}\text{Sn}$ filaments, but also actively introduce the appropriate pre-stresses, which can improve both the superconducting properties and the mechanical properties. The $I_\text{c}$ performance under transverse compression stress of the pre-bent and pre-tensioned Cu-Nb/$\text{Nb}_{3}\text{Sn}$ strands was higher than that of Cu/$\text{Nb}_{3}\text{Sn}$ strands. Furthermore, a significant suppression of $I_\text{c}$ degradation under transverse compression stress was also observed in the pre-bent Cu-Nb reinforced triplex. Therefore, the effective use of the Cu-Nb/$\text{Nb}_{3}\text{Sn}$ strands is expected to allow the manufacturing of cable-in-conduit (CIC) conductors by using React-and-Wind (R&W) method.