| 摘要 |
A cryogenic apparatus comprises a refrigerant vessel containing a superconducting magnet and a refrigerant, a vacuum casing containing the vessel, a radiation shield disposed between the vessel and the casing such as to enclose the vessel, a refrigerator for cooling at least one of the shield and the vessel, and a thermal conductive coupling disposed between the refrigerator and at the least one of the shield and the vessel, and turning on and off the heat transfer therebetween. The coupling includes, a first member having high thermal conductivity and connected to the refrigerator, and a second member having high thermal conductivity and connected to at the least one of the shield and the vessel, satisfactory heat transfer being obtained between the first and second members by supplying a heat conductive medium in the form of a fluid between the first and second members, only slight heat transfer caused by only a heat radiation being obtained between the first and second members by evacuating between the first and second members.
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