| 摘要 |
An electron beam generating device, wherein a high-resistance film is formed on the outer surface of an insulator provided with a cathode for emitting thermal electrons and a grid for collecting thermal electrons and forming an electron beam to allow a feeble current to flow to the high-resistance film, thereby preventing the accumulation of thermal electrons on the insulator and discharging. The upper portion of the high-resistance film connected to a chamber supplies an approximate reference potential to the upper portion of the film, and the lower portion of the high-resistance film connected to the grid supplies almost the same potential as that of the grid to the lower portion of the film to allow a feeble current to flow to the film. The prevention of accumulation of thermal electrons on the insulator can prevent discharging, accurately control the current capacity of an electron beam, and give the electron beam generating device a longer service life.
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