| 摘要 |
<p>PURPOSE:To arrange a metallic base and a filament in good parallelism and to stabilize current characteristic and cathode temperature by combining the metallic base and the filament with a projection formed either on the filament or the metallic base. CONSTITUTION:A disk cathode 24 comprises a metallic base 22 and a layer of an oxide 23. A cylindrical projection 26 having sufficient size, such as within double the width of the filament 25, is provided at the center part of the disk cathode 24. The disk cathode 24 and the filament 25 are suitably joined and fastened together by continuous welding 27 substantially around the projection 26 or by intermittent welding at 28 and 29, thus the filament 25 and the metallic base 22 being fixed together only at the projection 26 and the rest part of the filament 25 and the metallic base 22 being separated in parallel relationship, the current characteristic and the temperature of the cathode are stabilized.</p> |
