Performance test of a CuNb reinforced (Nb,Ti)3Sn coil fabricated by the react and wind method

In order to investigate the stress-strain and superconducting properties for a react and wind method under large electromagnetic stress states, a test coil with a large bore was fabricated using the highly strengthened CuNb/(Nb,Ti)₃Sn wire. We found that the analysis on the basis of the bending and tensile strains successfully explains the obtained mechanical properties. The operation currents could be applied, until the electromagnetic stress and strain became about 340 MPa and 0.34%, respectively. This is mainly due to not only the strong mechanical property of CuNb/(Nb,Ti)₃Sn wire but also the compression stress induced by the thermal contraction. As a result of the bending and tensile strain analysis for the critical current, the ratio of the quench current to the critical current was about 86% at 11 T and then decreased with decreasing magnetic fields.