Cryogen-free superconducting magnet fabricated by a react-and-wind method employing Nb_3Sn wires with CuNbTi reinforcement

摘要

Practical multifilamentary Nb_3Sn wires with CuNbTi reinforcement (CuNbTi/Nb_3Sn) exhibit the splendid mechanical tolerance of 340 MPa proof stress. We intended to develop a Nb_3Sn coil by a react-and-wind method for a wide bore cryogen-free superconducting magnet, and made a react & wind coil employing CuNbTi/Nb_3Sn wires. The performance test for the CuNbTi/Nb_3Sn coil was carried out, and the coil generated 2.2 T at 180 A as the individual test. In the combination test in a background field of 5.6 T, the react & wind processed CuNbTi/Nb_3Sn coil generated 7.5 T in a 220 mm room temperature bore. The wide bore cryogen-free superconducting magnet wound with highly strengthened CuNbTi/Nb_3Sn wires is now being used for a high field heat-treatment equipment at 7 T. This wide bore furnace provides special heat-treatment conditions of high temperature 1500℃ in fields up to 7.0 T in a 40 mm sample bore.