JPS6233759B

PURPOSE:To largely reduce a danger of introducing the trouble at a liquid refrigerator and a pump directly to the damage of a superconductor internally cooled by containing a superconductive wiring wound on the superconductor in a container filled with liquid helium. CONSTITUTION:A container 24 is provided within a vacuum heat insulating container 3, and liquid helium 14 is fully filled in the container 24. Superconductive winding 1 and valves 5a-5d are arranged in the container 24, and a pump 16 and a heat exchanger 17, etc. are also contained therein. Since the divided superconductive windings 1a-1c are dipped in the liquid helium 14 in this construction, the liquid helium 14 is impregnated into the periphery and the gap among the windings. Even if a liquid refrigerator 13, and the pump 16 are stopped, the cooling capacity while the stopped unit is recovered can be supplemented by the evaporation of the liquid helium 14 filled at the periphery. Thus, no problem occurs as long as the liquid helium 14 is existed.