HIGH HWR DEPENDENCE OF EROSION AND RETENTION IN-BEAM EXPERIMENTS AND ITS SIGNIFICANCE TO FUSION SYSTEMS

The erosion of low-Z graphite material and the hydrogen retention unde r particle bombardment are of special interest in fusion research. Fun damental research on erosion and hydrogen retention in low flux beam e xperiments is briefly reviewed. In large tokamak experiments, chemical erosion and radiation enhanced sublimation are not well understood fr om fundamental experiments using low flux beams. In high flux beam exp eriments which are carried out at the same order bombardment flux as i n tokamak experiments, sputtering yields are shown to have a strong de pendence with flux. The reduction dependence of this enhanced erosion serves as important information in the design of fusion reactors. The characteristics of retention and desorption in the supersaturation lev el under high flux bombardment are useful for understanding the dynami c retention related to fueling control and divertor behavior. (C) 1998 Elsevier Science S.A. All rights reserved.