Superconducting Characteristics of Nb₃Sn Cables Stranded with Ultra-fine Wires

Abstract

We are developing A15 cables made of ultra-fine wires for react-and-wind （R&W） magnet technology. Recently, we fabricated a bronze processed multifilament Nb₃Sn wire with a diameter of 50 µm. We also made a prototype Nb₃Sn cable by stranding 19 wires for testing. In this study, the transport critical current（I_c） of the cable was measured at 4.2 K and under an external field up to 18 T. The Non-Cu critical current density（J_c） was also calculated from the I_c results. For the I_c measurements, the cable was wound on glass fiber reinforced plastic（GFRP） cylinder bobbins after the heat treatment in straight geometry to replicate the R&W process. Four GFRP bobbins with different diameters were prepared to investigate the bending limit of the cable. The critical temperature（T_c） and magnetization properties of the cable were also measured by a magnetic property measurement system of Quantum Design.