| 摘要 |
PURPOSE:To reduce the consumption of liquid helium and facilitate continuous operation with a low cost with a simple structure by cooling a radiation shield and a superconductive coil directly by a freezer with heat transmission. CONSTITUTION:A radiation shield 5 is protected from heat penetration from external radiation by a vacuum heat insulating layer 4 between a vacuum container 7 and itself. The radiation shield 5 is also cooled directly by contact with the 1st heat absorbing member of the temperature of 80K or below with heat transmission and keeps the inside at the temperature of 80K or below. A superconductive coil 3 in the radiation shield 5 is directly and uniformly cooled by contact with the 2nd heat absorbing member 13 of the temperature of 4.2K or below with heat transmission through a temperature distribution equalizing member 14 to keep the superconductive condition. The 1st and the 2nd heat absorbing members 12, 13 are cooled by circulated gaseous nitrogen and gaseous helium cooled down to 80K or below and 4.2K or below respectively by adiabatic expansion by a freezer 11. Therefore, a large scale cooling apparatus such as a liquid helium continuous supply equipment or a gaseous helium exhaust and liquidizing and circulating equipment is not necessary so that the structure is simplified and the size and the weight are reduced and continuous operation is realized. |
