| 摘要 |
PURPOSE:To facilitate the setting of an effective magnetic field boundary and rotating angle so as to accurately adjust them by providing a sector-shaped electromagnet with a magnetic pole comprising the main body thereof the bow/ wedge-like magnetic pole pieces capable of moving freely along the main body. CONSTITUTION:A sector-shaped electromagnet 3A comprises a magnetic pole main body 6, bow-like magnetic pole pieces 7a, 7b arranged on both sides of the main body 6 and wedge-like magnetic pole pieces 8a, 8b arranged on the respective outer sides of the bow-like magnetic pole pieces 7a, 7b. As the starting point in a beam trajectory is shifted to G by changing the operating condition of an ion source 1, in order to change the ion beam current, the beam focus is shifted to H and the beam permeability is reduced. Thereby, in order to return the beam focus to F, it is necessary that the intensity of the magnetic flux in the electromagnet 3A is changed. For this purpose, the piece 7a is rotated in the direction of the arrow L so as to change the edge rotating angle U12 on the outgoing side to U2. When an effective magnetic field boundary position is shifted from K1 to k2, it is possible to make the position K, coincide with the position K2 by moving the piece 8a in the direction of the arrow M.
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