High flux 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 under particle bombardment are of special interest in fusion research. Fundamental research on erosion and hydrogen retention in low flux beam experiments is briefly reviewed. In large tokamak experiments, chemical erosion and radiation enhanced sublimation are not well understood from fundamental experiments using low flux beams. In high flux beam experiments which are carried out at the same order bombardment flux as in tokamak experiments, sputtering yields are shown to have a strong dependence 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 level under high flux bombardment are useful for understanding the dynamic retention related to fueling control and divertor behavior.