MANUFACTURE OF IMPREGNATION TYPE CATHODE

摘要

PROBLEM TO BE SOLVED: To easily remove excess emitter and lower the dispersion of electron emitting capabilities by heating an electron radiating substance formed into a prescribed shape and a porous metal substrate while keeping them in mutual contact and impregnating the substrate with molten electron radiating substance. SOLUTION: A porous tungsten substrate 7 and a formed emitter 12 are mounted on a Mo board 11 of a jig for impregnation. The resultant substrate and the emitter on the Mo board are heated in hydrogen furnace or vacuum furnace to melt and liquefy the formed emitter 12 and the tungsten substrate 7 is impregnated with the emitter by capillary phenomenon of the molten and liquefied emitter in all of the surface. The formed emitter 12 and the tungsten substrate 7 may be mounted on the Mo board 11 in this order. In the case excess emitter adheres to the tungsten substrate 7, the excess emitter is removed by washing, polishing, or other method to give a completed cathode pellet. The cathode pellet, a Ta sleeve, a Ta cup, a Mo thin film, a Sc2 O3 thin film, a W core wire, and an alumina coated-heater are assembled one another to provide an impregnated cathode.