First wall member of thermonuclear device and its making method

This invention concerns a first wall member used for a tokamak type thermonuclear device, free from peeling or abrasion even when exposed to high temperature plasmas. Silicon carbide is coated to the surface of a molybdenum substrate at a substrate temperature of lower than 900degC by means of plasma CVD. The thickness of silicon carbide formed on the molybdenum substrate is preferably within such a range of less than 300 μm as enabaling formation at a reduced cost, giving no undersired effect on the molybdenum substrate per se and obtaining sufficient close bondability with the substrate. Since the coating suffers from erosion of thermonuclear plasmas if it is too thin, by which the underlying molybdenum substrate is exposed, a thickness of not less than 5 μm is required. (H.T.)