CATHODE FOR CATHODE RAY TUBE WITH IMPROVED LIFETIME

摘要

Impregnated cathode for a vacuum tube comprising an emissive part in the form of a porous pellet 11 impregnated with a compound of alkaline earth metals; the pellet is placed in a dish 12 made of a refractory material and covered with a porous metal foil 13 forming the emissive surface of the cathode. Moreover, the pellet has a separation surface 18 between a heavily impregnated zone and a zone 10 which is not impregnated or weakly impregnated so that the said separation surface comprises at least a hollow part facing the emissive surface. By virtue of the shape of this separation surface, the lifetime of the cathode is improved.