Mechanical characteristics of Bi-2223 tape with a low matrix ratio

A 19 T cryocooled superconducting magnet with a 52 mm room temperature bore is currently under construction. The magnet consists of an outer NbTi section, middle Nb₃Sn section and innermost high-T_c section. The coils are exposed to an electromagnetic hoop stress following the magnetic field generation. In this 19 T cryocooled superconducting magnet, the high-T_c coil windings are Bi-2223 tapes with a low matrix ratio. Because of this, the mechanical characteristics, i.e., stress-strain characteristics, stress/strain dependence of the critical current and bending strain dependence of the critical current, were explored for the Bi-2223 tape. Furthermore, the small coil was wound with the superconducting tape. It was tested under magnetic fields to examine the stress-strain characteristics caused by the electromagnetic hoop stress.