| 摘要 |
PURPOSE:To reduce the intrusion of heat to a cryogenic refrigerant tank largely by installing a communicating hole closed when a power lead is retreated and a valve body capable of being abutted against and sealing the periphery of the communicating hole to the cryogenic refrigerant tank. CONSTITUTION:When power leads 5A, 5B are engaged with connectors 10A, 10B in order to complete the permanent current mode of a superconducting magnet 3, a valve body 19 is separated from the peripheral section of the communicating hole 22 of a cryogenic refrigerant tank 1 and the communicating hole 22 is opened, the gas of a cryogenic refriderant is flowed into a piping 4 for the power leads from the inside of the cryogenic refrigerant tank 1, and the power leads 5A, 5B are cooled. When the permanent current mode of the superconducting magnet 3 is completed and the power leads 5A, 5B are detached from the connectors 10A, 10B, the valve body 19 is abutted against and seals the peripheral section of the communicating hole 22 of the cryogenic refrigerant tank 1 and the communicating hole 22 is closed, the inflow of the cryogenic refrigerant gas from the inside of the cryogenic refrigerant tank 1 is stopped, and the inside of the piping 4 for the power leads is closed. The cryogenic refrigerant gas in the piping 4 is removed, and the inside of the piping is held under a vacuum or low pressure. Accordingly, heat loss due to a convection is prevented. |
