The electron impact surface of an anode/collector is coated with a carbon nanotube coating to reduce the production of secondary electrons and, concomitantly, to suppress the formation of neutral gases and plasma. A carbonizable resin is first applied to the electron impact surface, followed by a coating comprised of carbon nanotubes. The coating is pyro-bonded to the surface by heating the anode/collector to over 700.degree. C. in a non-oxidizing atmosphere. Next, the anode/collector is heated to over 1000.degree. C. while a low-pressure hydrocarbon gas, for example, methane, is flowed over the carbon nanotube coating. The gas decomposes and creates a smooth, non-porous, rigid surface on the carbon nanotube coating. The anode/collector is then heated in a vacuum to evaporate any residual water in the carbon nanotube coating.