Critical Current Characteristics of HTS Round Strand Using REBCO Tapes Under Transverse and Cyclic Load

Various strand concept for high-temperature superconductor (HTS) flat tapes have been developed in the past few years for fusion magnet applications. We developed a round HTS strand with soldered multilayer copper tapes as filler and support called SaMiT following the technic path of twisted stacked-tape cable. DC tests performed under bending and twisting condition demonstrated that the proposed design of the HTS strand is promising in the high current cable and magnet application, but the study on electromechanical properties against the transverse and cyclic load is still needed. A press device was designed to measure the critical current of SaMiT sample at 77 K and self-field as a function of transverse and cyclic load to simulate the electromagnetic force load during the magnet operation. Transverse load amplitudes have been applied up to 40 MPa and cyclic load up to 1000 cycles at certain load amplitude. The experimental results are presented and structural optimization suggestions are discussed with visual inspection and analysis.