| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem wherein, although the electron beam orbit in an interaction part of an electron beam 10 emitted from a cathode electrode 1 is kept by a cyclic magnetic circuit comprising a permanent magnet 6 and a pole piece 7, then the beam is excessively narrowed down to increase repulsive force between electrons because generation of the magnetic field by the cyclic magnetic circuit is rapid, and the beam orbit is not stabilized, whereby the electron beam is resultantly increased in waving compared to a desired electron beam orbit and in beam diameter. SOLUTION: An anode electrode is integrated with a pole piece to form an anode pole piece electrode 3, and the outer peripheral side and the inner peripheral side of the anode pole piece are formed of a magnetic material and a nonmagnetic material, respectively, whereby an immersion magnetic field to the side of an electron gun is intensified to smoothly focus the electron beam. COPYRIGHT: (C)2008,JPO&INPIT
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