| 摘要 |
PURPOSE: A fresnel plate structure and a method are provided to allow for a uniformity of magnetic field distribution by arranging plates, bars, or nets in a predetermined direction and removing localized magnetic disturbances. CONSTITUTION: A fresnel plate structure comprises two or more magnetic field focusing members which are processed from a magnetic material having characteristics of magnetic permeability 2.0 or higher in the temperature of -269 to +200 Deg.C, magnetic field resistance 1.0Oerstde or lower, saturated magnetization 10 gauss or higher, and curie temperature -269 Deg.C or higher. The magnetic material is processed into a shape of a plate, thin film, net, bar, pipe, or powder. The magnetic field focusing members are arranged at the interval of 1 to 100mm.
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