PURPOSE: To shield magnetism effectively by mutually overlapping and laminating a plurality of oxide superconductor blocks.
CONSTITUTION: A large number of blocks (small pieces) consisting of an oxide superconductor such as the oxide ceramics of yttrium-barium-copper are mutually superposed and laminated so that magnetism is not leaked, thus composing a magnetic shielding body. The blocks of the superconductors show the action of complete diamagnetism (a Meissner effect) in a first critical magnetic field or less to magnetism, magnetism cannot intrude completely into the magnetic shielding body constituted of the block 9 of the superconductor in the first critical magnetic field or less, and considerable shielding action is acquired even in the first critical magnetic field or more. Since the oxide ceramics of yttrium-barium-copper utilized as the superconductor begin to display a superconductive state at approximately 90 K, magnetic shielding action is also conducted at a liquid nitrogen temperature (approximately 80 K) level.
SHIRAKU YOSHINORI
OGATA HISANAO
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