| 摘要 |
PURPOSE:To make it possible to use a hot cathode stably without receiving effects of sputtering while using by providing a cover of insulating matter around a terminal part of conductive ceramic. CONSTITUTION:A terminal part refers to a part around two terminals of a heating body including a part of insulating matter for energizing the heating body. To prevent deposition of metal on the surface of the part 6 of insulating matter which may cause shortcircuit between the terminals, the part 6 of insulating matter composing a hot cathode is completely covered. In addition, for preventing deterioration in thermoelectron emission characteristics because of deposition of metal on the heating body, all the metal parts composing the hot cathode are covered. |
