| 摘要 |
PURPOSE:To shield a magnetic field from the exterior to interior or in reverse direction thereto by burying a liquid nitrogen container in a member for forming an insulation vessel, arranging a superconducting material at least on the whole inner or outer surface, and forming a liquid nitrogen inlet in the container. CONSTITUTION:When liquid nitrogen is filled in a nitrogen container 2 arranged in a member for forming an insulation vessel 1, the container 2 and the periphery of the container 2 are cooled to the vicinity of the liquid nitrogen temperature. Accordingly, a superconducting material 3 arranged in the container 2 or on at least one of the inner and outer surfaces is cooled to the vicinity of the temperature, and the material 3 is superconducted. Thus, the material 3 shields magnetism by Meissner effect.
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