Superconducting properties and thermal stability of high-strength Nb3Sn wire with Ta-reinforced filaments

Superconducting properties of high-strength Nb₃Sn wires with Ta-reinforced filaments were evaluated at various temperatures and magnetic fields. Mechanical properties were also investigated at 4.2 K. The critical current was measured at temperatures up to 14 K and in magnetic fields up to 15 T. The data were well scaled by using empirical scaling laws. The stress-strain curve showed that the stress corresponding to 0.5% strain was 284 MPa. The value is twice as large as that of conventional Nb₃Sn wires, indicating that the high-strength Ta reinforcement enhances the mechanical property of the wire. Furthermore, the wire was sufficiently ductile. To evaluate the thermal stability, minimum quench energy and normal zone propagation velocity were measured under a cryocooled condition. The Ta reinforced Nb₃Sn wire shows relatively high stability and large propagation velocity. The results suggest that the Ta reinforced Nb₃Sn wire has sufficient applicability for cryocooled superconducting magnet windings.