The electron impact surface (19) of an anode (13) is coated with a carbon nanotube coating (21) 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 (19), followed by a coating (21) comprised of carbon nanotubes. The coating (21) is pyro-bonded to the surface (19) by heating the anode (13) to over 700° C in a non-oxidizing atmosphere. Next, the anode (13) is heated to over 1000° C while a low-pressure hydrocarbon gas, e. g., methane, is followed over the carbon nanotube coating (21). The gas decomposes and creates a smooth, non-porous, rigid surface on the carbon nanotube coating (21). The anode (13) is then heated in a vacuum to evaporate any residual water in the carbon nanotube coating (21).