| 摘要 |
PURPOSE:To cause radiant heat to be absorbed well by radiation shields for decreasing excessive current loss, by forming the radiation shields of a good heat conductor into a cylindrical shape while providing them with rail-shaped insulation sections extending axially in angular regions different from each other in the circumferential direction. CONSTITUTION:A magnetic shield 23 is provided between a lowtemperature radiation shield 23 and a helium container 12 storing liquid helium 18 and a magnetostatic coil 11, the magnetic shield 23 being formed so as to surround the helium container 12 closely thereto. A high-temperature radiation shield 27 is provided between the low-temperature radiation shield 23 and a vacuum container 14 such that it is coupled to a nitrogen container 16 storing liquid nitrogen 19 in a heat conducting relation. The bore tube 25B of the magnetic shield 25 is formed of a good heat conductor into a cylindrical shape. The bore tubes 27B and 23B of the high-and low-temperature radiation shields 27 and 23 are also formed of a good heat conductor into a cylindrical shape, and they are provided with rail-shaped insulation sections 28 extending axially in angular regions different from each other by 180 deg.C in the circumferential direction. |
