Improvement in Stability and Operating Characteristics of HTS Coil Using MIT Material

This paper proposes a new method of achieving electrical stability and controllability of a high-temperature superconductor (HTS) coil. The proposed method applied a material with a metal-insulator transition (MIT) property to the turn-to-turn resistance of an HTS coil. As a result, the turn-to-turn resistance remained at the insulator level in the normal state, thus removing delay during charging and discharging. During transient state, the turn-to-turn resistance dropped to the metal level, and current bypass occurs similar to that in a noinsulation coil, thus preventing the coil from burning out. The validity of the MIT characteristic and the proposed method were verified through experiments.