Evaluation of various Nb-rod-method Cu-Nb/Nb3Sn wires designed for practical React-and-Wind coils

Bronze-processed Cu-Nb/Nb3Sn wires, composed of the Nb-rod-method Cu-Nb reinforcing stabilizer around the Nb3Sn filament bundle, have superior mechanical strength after Nb3Sn reaction heat-treatment at both low temperature and room temperature. The Cu-Nb/Nb3Sn wires are able to be applied to the react-and-wind (R&W) process. Moreover, the non-Cu- J c values of Cu-Nb/Nb3Sn wires are remarkably increased by using both the high-tin-bronze and appropriate pre-bending treatments. In this study, we developed Cu-Nb/Nb3Sn wires with various cross-sectional structures which were improved the I c values under tensile stress and transvers compression stress. Also, we confirmed I c improvements by pre-bending treatments of a Cu-Nb/Nb3Sn triplet cable and small size Rutherford cables. Cu-Nb/Nb3Sn wires and cables can be designed on requirements of Nb3Sn coils.