| 摘要 |
<p>PURPOSE:To prevent the occurrence of heat deformation and noise in a grid, by making it consist of a cathode sleeve, a cathode having a small outer diameter as compared with an inner diameter of this barrel part, and a setting device installing this cathode in an opening end of the cathode sleeve. CONSTITUTION:After a cathode 12 is inserted into a cathode inserting port 14a, a lower surface inclusive of this cathode 12 is brazed, and the cathode 12 and a spacer 14 are unitized in one. Afterward, this spacer 14 holding the cathode 12 is fitted in an opening end of a cathode sleeve 10, and the opening end is fixed by means of welding or brazing. Since a cathode surface of the cathode 12 comes to one-fifth or sixth as compared with an opening area of the cathode sleeve 10, beam flux of radiation electrons becomes narrowed. With this constitution, when a grid 4 having fine aperture 4a is set up, unwanted electrons flowing into this grid 4 are sharply reduced, thus heating of the grid, the occurrence of noise, etc., are all preventable.</p> |
