Persistent current HTS magnet cooled by cryocooler (2) - Magnet configuration and persistent current operation test

An high temperature superconducting (HTS) magnet, consisting of an HTS coil, a persistent current switch, a GM type two-stage pulse tube cryocooler, and YBCO current leads was developed. Detachable current leads were adopted to reduce heat leakage during persistent current operation. The HTS coil was cooled to approximately 10 K and persistent current mode operation tests were carried out at various currents up to 532 A, which is the rated current. Current decay at each persistent current mode operation was investigated by measuring the magnetic field at the center of the coil. The current decay rate at the 532 A operation was found to be approximately 0.44%/day.