| 摘要 |
PURPOSE:To improve the withstand voltage treatment between electrodes by properly specifying the mutual assignment of an electrode to which forcussing voltage is applied and that to which anode voltage is applied. CONSTITUTION:The electrode gaps b1 and b2 opposed to a G4 electrode 24 which becomes a high potential electrode and is inserted from both sides by a G3 electrode 23 and a G5 electrode 25 which are set to be a ground-potential at high voltage treatment are equalized to the conventional opposed electrode gap or increased. The electrode gap b3 between the G5 electrode 25 which is made ground-potential and a G6 electrode 26 which is only onesidedly high potential electrode is specified so as to become smaller than the electrode gaps b1 and b2. However, the mutual electrode gaps b1 and b2 must prevent an electron beam from being undesirably bent due to the effect of an external magnetic field and the mutual electrode gap b3 from degrading the withstand voltage characteristics between the electrodes. |
