Low energy (10 to 700 eV) angularly resolved sputtering yields for D+ on beryllium

The phenomenon of ion induced sputtering is integral to many applications. In magnetically confined fusion, this sputtering is important for both the lifetime of the plasma facing components and the contamination of the plasma. A method has been developed to obtain both the angular distribution and the total sputtering yield. The total yield is determined by collecting the sputtered material on a quartz crystal microbalance. The sputtered material is also collected on a pyrolytic graphite collector plate. By mapping the concentrations of the sputtered material on this plate, both the polar and the azimuthal angular distribution can be determined. Utilizing this set-up, data have been obtained for 10 to 700 eV D+ on beryllium at a 45 degrees angle of incidence to the normal. Subthreshold sputtering (0.004 +/- 0.003 at 10 eV) has been observed. These data are some of the first to become available, especially at the lower energies.