Secondary Electron Emission Yields of Carbon Coated Copper and Niobium Real Surfaces

Real copper and niobium surfaces, that is surfaces which have been in contact with the air and cleaning agents, and in consequence are covered with a thin layer of adsorbed molecules, have a total secondary electron yield (SEY) greater than one. To reduce SEY, various carbon coatings, deposited on real surfaces have been studied: thin evaporated graphite films, implanted C+ ions, sprayed carbon and carbonsoot layers. In all cases, SEY decreases, but always remains above one in a primary electron energy domain except for soot, giving SEY values as low as O.5.