Erosion and surface morphology of graphite materials under high flux beam irradiation

Surface morphology and its relation to the erosion mechanism of graphite ma terials (pyrolytic graphite (PG) and isotropic graphite) irradiated by high flux beams were studied. The irradiation was made by a 5 keV Ar beam with a maximum flux of 1.3 x 10(21) Ar/m(2) s with irradiation angles and fluenc es, and sample temperatures as experimental parameters. In the case of PG, the surface morphology was different between irradiation at RT (physical sp uttering) and at elevated temperatures (1980 K, radiation enhanced sublimat ion (RES)). In addition, irradiation at oblique incidence (60 degrees) tend ed to Batten the surface at RT, while at 1980 It the surface roughness deve loped to some extent. No clear flux dependence of the surface morphology wa s observed at 1980 K as long as the mean eroded depth was similar, though t he RES yield was flux-dependent(decrease with flux). Tn the case of isotrop ic graphite, the distinctive surface morphology observed for PG was not fou nd. (C) 1998 Elsevier Science B.V. All rights reserved.