2G HTS Racetrack Coil Protection Using Smart Switching Feature of V₂O₃

Abstract

A smart switching feature was investigated in this paper by applying V2O3 to a second-generation high-temperature superconductor racetrack coil in an experiment. V2O3 is a material with metal-insulator transition characteristics and is currently being studied for use in smart insulation. If the insulation film in an existing superconducting coil is replaced by V2O3, the coil operates normally under steady-state conditions, like an insulation coil. In the event of a quench, a turn-to-turn current bypass occurs. Such a highly transient state causes a current sharing phenomenon, as in a no-insulation coil, which results in a drastic decrease in the magnetic field. In this paper, this phenomenon is referred to as smart switching. We conducted an experiment to verify the effectiveness of smart switching in protecting superconducting coils. In addition, we performed experiments to verify that smart insulation, as proposed in this paper, is stable and controllable. Unlike the conventional single pancake experiment applied for a few turns, our experiment fabricated a racetrack coil with more than 100 turns.