Overview of fundamental study on remountable HTS magnet

A remountable HTS (high temperature superconducting) magnet was proposed for one of the future designs of fusion reactors. It can facilitate the fabrication of the magnet itself and the replacement of failed parts and of the inner structural material components in the maintenance phase. The butt joint of HTS cable was investigated for the concept. At first, performance of the butt joint of BSCCO 2223 tape was evaluated by experiments and numerical analyses to clarify the basic property of the butt joint. Then experimental evaluation of the butt joint of laminated BSCCO 2223 cable was carried out to prove robustness against heat generation at jointing parts at liquid nitrogen temperature and several hundred amperes. Based on the proof, the prototype of the remountable HTS magnet by using the butt joint was fabricated and the performance was evaluated to suggest some issues for the future development. The above fundamental studies on the remountable HTS magnet are summarized in this paper.