Design and Electromechanical Properties of Round HTS Strand With Soldered Multilayer Copper Tapes as Filler and Tube

Design and feasible verification of the round high-temperature superconducting (HTS) strand with REBCO tapes is the key technology for future fusion magnet application such as China Fusion Engineering Test Reactor (CFETR). Flat tape configuration of REBCO tapes and incompatibility with cable design based on round low-temperature superconducting (LTS) strand lead to the development of new cable technology. In this article, a HTS strand variant with soldered multilayer copper tapes as filler and tube called SaMiT is developed following the technology path of twisted stacked-tape cable (TSTC). Due to the use of a milling process to form the round strand, the probability of REBCO tapes damage is reduced greatly in the manufacturing process. Meanwhile, the tapes delamination problem and solution is also discussed. The bending and twisting test of the samples are performed to verify the electromechanical characteristics. The measurement result shows the SaMiT has great potential in HTS cable application. Future tests at transverse load and high field are needed for fusion magnet application.