Abstract: A discharge pipe is connected to a refrigerant container from outside of a vacuum container, and discharges a vaporized refrigerant. A pair of external leads are electrically connected respectively to opposite ends of a superconducting coil from a position outside of the vacuum container, so as to cause a current to flow through the superconducting coil. A protection circuit is electrically connected to the superconducting coil, and consumes energy stored in the superconducting coil during quenching. The protection circuit is in contact with the discharge pipe outside of the vacuum container.

Abstract: A permanent current switch apparatus according to an embodiment is a permanent current switch apparatus electrically connected to a superconducting coil via a superconducting wire, the permanent current switch apparatus including a plurality of parallel structures with thermal permanent current switches connected in parallel, the thermal permanent current switches being capable of switching between conducting and interrupting an electric current flowing through the superconducting wire. The parallel structures are connected in series.

Abstract: A discharge pipe is connected to a refrigerant container from outside of a vacuum container, and discharges a vaporized refrigerant. A pair of external leads are electrically connected respectively to opposite ends of a superconducting coil from a position outside of the vacuum container, so as to cause a current to flow through the superconducting coil. A protection circuit is electrically connected to the superconducting coil, and consumes energy stored in the superconducting coil during quenching. The protection circuit is in contact with the discharge pipe outside of the vacuum container.