Enhancement of high-temperature superconducting coil stability using doped smart insulation materials for superconducting magnet applications

This study reports a high-temperature superconducting (HTS) coil containing molybdenum doped vanadium trioxide (V2O3:Mo) as turn-to-turn insulation material to ameliorate the electrical properties of both insulated and non-insulated (NI) coils. The electrical characteristics and thermal stability of the V2O3:Mo insulated coil against NI and V2O3 insulated coils were investigated through charge-discharge, over-current, and quench tests. The findings revealed that the V2O3:Mo and V2O3 insulated coils demonstrated a faster charge/discharge rate than the NI coil due to the high resistance of the V2O3: Mo or V2O3 insulator which obstructed the current to flow away from the azimuthal current path. In the over-current test at 160A, the V2O3:Mo insulated and NI coils exhibited higher electrical stability than the V2O3 insulated coil because the excessive currents above their critical values bypassed between the turn-to-turn contact. Moreover, the V2O3:Mo insulated coil demonstrated a 2.1times improvement in the minimum quench energy compared to the V2O3 insulated coil at 70 % of the coil's current-carrying capacity, which is an essential performance parameter for the operation of superconducting magnets.