Measurements of erosion mechanisms from solid and liquid materials in PISCES-B

PISCES-B is a steady-state linear-plasma simulator facility dedicated to the study of plasma–material interactions. This paper will summarize recent experiments conducted in PISCES in the areas of: plasma–liquid-metal interactions, the flux dependence of the chemical erosion of graphite, and surface modification to tungsten samples exposed to high-fluence plasmas. Enhanced erosion of liquid-metal samples exposed to plasma is observed for both lithium and gallium samples. The surface stratification of liquid-metals is discussed as a possible explanation. The importance of correction terms in the interpretation of the chemical erosion measurements from graphite samples is then emphasized. And finally, surface analysis of tungsten samples, after deuterium plasma bombardment, has revealed microscopic damage in the surface at ion energies below the sputtering threshold energy. This damage appears to be due to pockets of deuterium gas forming within the tungsten and subsequently rupturing.