ARS'I'RACT:Shielding laclor of a BSCCO 22 12 phase HTc superconducting cylinder had a maxiinurn or 10~" .evcn though the cylinder had a large length/diameter ratio enough to be expected that shielding factor exceeded IO'. In this paper two models are proposed to discuss the leakage of the magnetic field in the superconducting cylinder under experimental results of the shielding properties.

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The Biomagnetism measurement is required shielding effect 1/S≦1/10 −7 for using SQUID magnetometer. The superconducting shield is possible to realize ideal low magnetic noise space. But it is required to attenuate every external field inside the superconducting hollow cylinder equally. Especially, radial external field decreases gently comparison to axial field. At this time the length of cylinder needs 4.4 m for diameter 1 m to realize shielding effect 1/S≦1/10 −7 . On the other hand, it is only 2.1 m for axial field. For that reason, we devised two methods to attenuate radial field rapidly coupled with permalloy. K E Y W O R D Sbiomagnetism, magnetic shield, permalloy, permeability, SQUID, superconductor Electr Eng Jpn. 2019;207:3-14.

A magnetically shielded room (MSR) is constructed by combing superconducting panels with normal conductive junctions. The MSR is composed by vacuum insulation panels, a tank for liquid nitrogen for superconducting panels and a ferromagnetic door. Thermally insulating vacuum panels, a reservoir of liquid. nitrogen to cool the superconducting panels and ferromagnetic door make up the MSR.