The effects of a glow discharge on glass and organic materials

Abstract

The effects are described of exposing glass and organic materials to a glow discharge operated at 5 kV. Bombardment of high velocity electrons from the cathode dark space produces contaminant films if hydrocarbon vapours are present. Positive ions accelerated on to a glass surface may remove constituents of the glass and superimposed metal oxide films. The selective removal of material from the glass surface lowers its refractive index. Ion bombardment also removes hydrocarbon decomposition products from surfaces previously exposed to electron bombardment. Polymerized films are not readily formed in the positive column of a high pressure glow discharge because the electrons have insufficient energy to dissociate the hydrocarbon molecules. Plastic materials exposed to a glow discharge are invariable degraded. Damage arising from electron bombardment increases with bombardment time, whereas that due to ion bombardment tends to reach a constant value. It is believed that ion bombardment partially damages the polymer and sputters carbon and unsaturated molecules so that the remaining damaged surface material is an equilibrium quantity.