| 摘要 |
PURPOSE:To form simple structure, and to adjust the distribution of a magnetic field easily by movable mounting a subpermanent magnet, in which a magnetic pole having the same polarity as a magnetic pole near to a pole piece in magnetic poles for a permanent magnet is magnetized so as to be directed to a space, outside each pole piece. CONSTITUTION:Subpermanent magnets 7, 7' are magnetized in the direction orthogonal to the direction of magnetization of permanent magnets 2, 2', and magnetic poles on the space 5 side are magnetized so as to be brought to the same polarity as the inner circumferential side magnetic poles of the permanent magnets 2, 2'. A magnet having large magnetomotive force such as a rare earth-iron-boron magnet is desirable in the same manner as the permanent magnets as the quality of materials of the subpermanent magnets. The subpermanent magnets 7, 7' are housed in grooves 9, 9' shaped to guide members 8, 8' consisting of a non-magnetic substance, bolts 10, 10' are fixed to the end surfaces of the subpermanent magnets, and the bolts are screwed into arms 11, 11' fastened to the guide members 8, 8'. When the bolts 10, 10' are turned, the subpermanent magnets 7, 7' are moved in the direction of the arrow (a). Accordingly, the quantity of the flux of pole pieces 3, 3' changes, thus adjusting the distribution of a magnetic field in the Z direction.
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