Butt jointing performance for remountable HTS magnet by improving contact surface condition

The remountable HTS magnet, which can facilitate the fabrication of the magnet itself and the replacement of failed parts and of inner structural component, was proposed by the authors, especially for helical reactors and Spherical Tokamak. Through the previous researches, it has been clarified that the butt joint of HTS cable is a suitable joint method for the remountable magnet. In this study, the butt jointing performance of BSCCO 2223 cable is evaluated when the contact surface is metal-electroplated or coated with nano-carbon particles. The results show that electroplating of silver can reduce the joint resistance. The joint resistance obtained by this experiment is small enough to prevent significant resistance increase below 500 A. It is proved that the HTS cable has enough robustness against heat generation in the butt joint under liquid nitrogen temperature below 500 A, which shows future feasibility of the remountable HTS magnet.