Development Progress and Future Prospects of Cu-Nb Reinforced Nb₃Sn Wires

Abstract

The Cu-Nb/Nb 3 Sn wires have much higher superconducting properties under large mechanical stresses compared to conventional Cu/Nb 3 Sn wires. In the developments of the Cu-Nb/Nb 3 Sn Rutherford cables for 25 T cryogen-free superconducting magnet with Tohoku University, we succeeded in improving both superconducting performance and mechanical properties by prebending treatment using the React-and-Wind (R&W) method. Subsequently, we have made many prototypes of Cu-Nb/Nb 3 Sn wires that satisfy the properties required for various Nb 3 Sn coil applications. As a result, we established technologies related to Cu-Nb/Nb 3 Sn wires such as higher strength, higher critical current density, rectangular shape, enamel coating, thinner wires for small radius bending, and stranded cables. We also confirmed the effectiveness of Cu-Nb/Nb 3 Sn wires not only in the R&W method but also in the W&R method. This paper describes the development progress and future prospects of Cu-Nb/Nb 3 Sn wires.