Mechanical and superconducting properties of Bi-2223 tape for 19 T cryogen-free superconducting magnet

We have started a new project to develop a cryogen-free 19 T superconducting magnet with a 52-mm room temperature bore. The magnet is designed to be consisting of three sections, i.e., the innermost high-T_c superconducting coil section, the middle Nb₃Sn section and the outer NbTi section. The electromagnetic hoop stress is applied to the superconducting wire due to the magnetic field generation. It is described to the products of magnetic field, transport current density, and winding radius. The maximum electromagnetic stress is estimated to exceed 200 MPa in the middle Nb₃Sn section and 50 Pa in the high-T_c section. It is important to explore the mechanical characteristics to design the magnet. In this study, mechanical properties, i.e., stress-strain characteristics and stress dependence of the critical current, were investigated for oxide superconducting tapes.