CATHODE FOR ELECTRON DISCHARGE DEVICE HAVING HIGHLY ADHERENT EMISSIVE COATING OF NICKEL AND NICKEL COATED CARBONATES

摘要

An application of metal particles comprised substantially of nickel to a nickel containing cathode substrate is followed by the application of potentially emissive materials comprised of nickel coated carbonates of barium and/or strontium and/or calcium. The particles and nickel coated carbonates are diffusion bonded or welded to the substrate and to each other after the cathode is mounted in a tube, simultaneously with activation of the cathode. The coating thus provided is very adherent and reduces arcing during high voltage applications. An alternate embodiment for further increasing adherence of the emissive material comprises adding a nickel etching agent, such as barium nitrate, to the potentially emissive material suspension. During the temperature increase noted above to activate the cathode, the etching material first melts and densifies the carbonates and then decomposes to etch the nickel particles and the substrate. Further heating changes the etching material and stops the reaction.