Erosion of Be as plasma-facing material

The knowledge of the erosion of Be, BeO, Be2C, and Be4B due to ion bombardment is reviewed. The sputtering yield values obtained experimentally and by computer simulation are given for H, D, T, He, Be, C, O, Ne, and Ar bombardment. The dependence of the yield on ion energy and angle of incidence is discussed as well as the influence of the target temperature and surface roughness. For the case of C and O bombardment the result of surface composition changes due to accumulation of incident ions in the surface layer is discussed and effects due to simultaneous bombardment of hydrogen and C impurity ions are described. Finally, Be is compared to other potential plasma facing materials, such as graphite or tungsten, on the basis of the ratio of the tolerable plasma impurity concentration to the sputtering yield. The effects of a Maxwellian incident energy distribution of deuterium ions or the energy distribution typical for charge exchange neutral deuterium atoms are taken into account. Consequences for the use of Be in future fusion plasma experiments are regarded.