| 摘要 |
PURPOSE:To secure such a stable ion source as having no dielectric breakdown due to discharge at a range where gas pressure is high and current density is large, by constituting an insulator, holding two electrodes, so as not to expose a metal supporter to an ionization chamber constituting the ion source. CONSTITUTION:An insulator 11 holding an emitter electrode 2 and a drawer electrode 3 is formed there so as not to expose a metal supporter to an ionization chamber 8 constituting an ion source. That is to say, the insulator 11 composed of unizied quartz is used. With this constitution, a surface of the metal supporter 7 to the ion source is completely isolated by an insulating material, so that such a route that causes dielectric breakdown is interposed.
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