| 摘要 |
PURPOSE:To increase leakage magnetism into a collector and focus an electron beam by means of an intense reversal magnetic field by making an end nearest the collector consist of only magnets and removing a pole piece in a periodic permanent magnet focussing device. CONSTITUTION:A two-stage collector section supports the primary collector 10 that is adjacent to a high frequency circuit section and the secondary collector 11 that is far from it in a collector vacuum enclosure 13 using an insulator 12. Suppose that the voltage applied to a helix 3 is V, 0.5V and 0.25V voltages are applied to the primary and secondary collectors 10 and 11, respectively. In this case, a permanent magnet 7 is located nearest the primary collector 10 and a pole piece 8 is removed. Thus leakage magnetism is increased toward the collectors from the permanent magnet 7 and an intense reversal magnetic field is generated within the primary collector 10. This intense reversal magnetic field prevents the sudden divergence of the electron beam which flows into the collector, guides the electron beam to the lower potential secondary collector 11, and improves overall efficiency. |
