Plasma-induced morphology of beryllium targets exposed in PISCES-B

The surface morphology that results from exposure of beryllium targets in the PISCES-B linear plasma device to light-ion (D or He) plasma is investigated as a function of the incident ion energy distribution, the incident ion angle with respect to the surface and the temperature of the surface. Nearly identical cone-like surface structures result regardless of the ion energy distribution or the incident angle of the ions. Increasing the target temperature on the other hand decreases the resultant surface roughness. Differences in the shape of the cones that develop on the surface due to either deuterium or helium plasma exposure agree with models of ion surface interactions. Ion trenching at the base of the cones has been observed and may explain the resulting dense array of cones across the surface following high-fluence plasma exposure.