| 摘要 |
PURPOSE:To prevent breakdown of a glass envelope due to the secondary electrons or the like by making a gap between a cathode holding plate and a metal envelope an insulation marginal distance and disposing the holding part by bending the outer peripheral part thereof giving roundness toward the glass envelope on the cathode side. CONSTITUTION:An X-ray tube is composed by oppositely arranging a rotary anode 1 and a cathode 2 inside an envelope whose middle part 4 is made of a metal while both ends are made of glass. Thereby, a cathode holding plate 3 is enlarged so far as the gap between the metal envelope 4 and itself reaches the insulation marginal distance and its outer peripheral part is given roundness while fixing a bent opening end toward the glass envelope 6 on the cathode side. Further, the opposite surface of the holding plate 3 to the anode 1 is formed while being given blackening treatment. Accordingly, stray electrons inside the tube and the secondary electrons from the anode 1 are prevented from flying to the glass envelope 6 on the cathode side while making the holding plate 3 to efficiently absorb infrared rays of the anode 1 thus simplifying degassing of the holding plate 3. |
