| 摘要 |
PURPOSE:To obtain an oxide coated cathode suitable for a low current range action generating no change in the cut-off voltage by precisely forming the surface part of an oxide layer compared with the oxide layer part on the part of the cathode base. CONSTITUTION:An oxide layer 5 attached to the terminal of the cathode base 3 has the relatively precise face part 5a, in which a fall h between a valley and a mountain of the unevenness on the surface part 5a shall be about 3-5mum. Further, the oxide layer part 5b on the cathode base side 3 is roughly formed compared with the surface part 5a. The oxide layer part 5b of the cathode base is roughly formed under the same condition as before while reducing the interval between the nozzle of a spray gun and the cathode base for forming the oxide layer part 5a on the thin surface side. Thereby, the oxide coated cathode, which is suitable for the low current range action while giving no change in cut-off voltage and generating no disorder in the direction of electron emission or no falling-off in the oxide layer, can be obtained at a low price. |
