An exit window for an electron beam emitter through which electrons pass in an electron beam includes an exit window foil having an interior and an exterior surface with a series of holes formed therethrough. A corrosion resistant layer having high thermal conductivity extends over the exterior surface and the holes of the exit window foil for resisting corrosion and increasing thermal conductivity. The layer extending over the holes of the exit window foil provide thinner window regions which allow easier passage of the electrons through the exit window.