Bombardment of Plastics in a Glow Discharge

Abstract

THE cathodic sputtering of metals in a glow discharge has been studied by many workers, but the sputtering of non-metallic substances has received limited attention. I have shown that inorganic materials such as metal oxides and glass may be sputtered from a glass target exposed to positive ion bombardment¹ and have recently extended my investigation to include plastic materials. The bombardment apparatus consisted of two opposing electrodes made from aluminium sheet, 4 in. × 3 in., spaced 4 in. apart with an aperture 0.5 in. square in the centre of both electrodes. The plastic specimens were mounted behind each aperture and bombarded by electrons or positive ions according to the polarity of the electrodes. The current densities of the particles bombarding the specimens were not known but it was assumed that they were similar to those flowing to the metal electrodes, because surface tracking and internal breakdown did not occur with either specimen. Also, a stable discharge was obtained with a continuous cathode dark space in the region of the electrode aperture.