人体サイズ縦置き円筒型両端開口磁気シールドの製作及び評価

概要

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We developed a human-size, open-structure, vertical cylindrical magnetic shield consisting of four shells. The inside diameters of the four shells are 0.67m, 0.72m, 0.82m and 0.97m, respectively. The lengths of the shells are 1.80m, 2.20m, 2.43m and 2.75m, respectively. The first shell is made of Permalloy (2.1mm thick). Other three shells, made of amorphous ribbons (approximately 50mm wide, approximately 22 μm thick), employ magnetic shaking. The second shell consists of four subdivided helical shells with internal space of about 10mm. Each subdivided helical shell comprises of 12 layers, with the amorphous ribbons wound helically. The outer two shells have an axial stucture, in which the ribbons are placed along the axial direction of the cylinder. The third shell has 26 layers and the fourth shell has 30 layers of the amorphous ribbons. The shielding factor measured at the center was approximately 100, 000 for the transverse magnetic field and approximately 380 for the axial magnetic field, the amplitude of the magnetic field being in both cases 10, 000 nT. The leakage field from the shaking coils at the center of the shield was below 1 nT permitting operation of highly sensitive SQUID magnetometers.
社団法人日本磁気学会の論文
2000-04-15