| 摘要 |
PURPOSE:To provide an impregnated cathode structure which has not only its initial current property but also favorable electron discharge property even if used for a long time under high-density current by specifying the quantity of potassium in an alloy cover film constituting a cathode carpet, in the above cathode structure which has respectively specified cathode pellet and heater. CONSTITUTION:A cathode pellet 12 is equipped with a high temperature fusing metal porous substrate 12A impregnated with electron emission matter 12B consisting of polyoxides containing BaO and an alloy cover film 12C consisting of one or more metal (alloy) selected from Ru, Os, Ir, and W, staying on the electron emission face of this substrate 12A, and the high temperature fusing point metal porous substrate 12A by thermal diffusion. In the above cathode structure having this cathode pellet 12 and the heater 19 for heating the cathode pellet 12 and contained in a high temperature fusing point metal sleeve 15, the total content of potassium contained in the alloy cover 12C overlaid on the electron emission face of the cathode pellet 12 is limited to a value within 0.5wt.%. |
