| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a reliable cathode support structure which prevent generation of unnecessary thermionic emission due to evaporation of an emitter deposited at the top end of a cathode cylinder. SOLUTION: A cathode holding cylinder of the cathode support structure is composed of an upper cathode holding cylinder 2a and a lower cathode holding cylinder 2b separated from each other to electrically insulate. An impregnated cathode structure 6 is multi-point laser welded to the lower cathode holding cylinder 2b. In this structure, no potential difference is generated between the cathodes because no drive voltage is applied to the upper cathode holding cylinder 2a. Therefore, even if the emitter deposited at top of the upper holding cylinder evaporates in the producing process or a life test, no unnecessary thermonic emission is generated and no insulation failure occurs between the cathodes.</p> |
