JPS6422008A - Magnetic yoke - Google Patents

Abstract

PURPOSE:To broaden the width of the uniform section of the distribution of magnetic flux density formed between gaps further, and to obtain a magnetic yoke, magnetic flux density of which is increased, by installing a yoke consisting of a ferromagnetic substance and having a surface through which magnetic flux must be passed, and of a diamagnetic substance covering surface except the surface through which magnetic flux must be passed. CONSTITUTION:A magnetic yoke 10 has yokes 11 and 12 composed of a pair of columnar ferromagnetic substances centering around an axis 21, and flat edge faces 15 and 16 at the noses of tapered sections 13 and 14 are opposed and separated mutually and a gap 17 is determined between these edge faces. Superconductors 20 and 22 are mounted to each yoke 11 and 12 so as to surround the side faces of the nose sections of yokes including at least the tapered sections 13 and 14. An reaching a critical temperature or less, the semiconductor zeroes in electric resistance and becomes impermeable to magnetic flux. Consequently, the superconductor 20 does not form a closed circuit in the periphery of the yoke 11, and currents are induced in the superconductor 20 under the state of the closed circuit, thus preventing the generation of an undesired magnetic field. Accordingly, leakage flux passing through the insulator section of the superconductor can be minimized.