Sputtering-erosion estimates for NBETF beam dumps

To stop multi-second high-energy hydrogen or deuterium beams in neutral injection systems, thin-skin actively cooled dumps made of Cu, Mo, or W are contemplated. For the Neutral Beam Engineering Test Facility (NBETF), the design goal for the life of the beam dumps is 25,000 thirty-second pulses, with a fluence of 10/sup 23/ deuterons/cm/sup 2/. From a review of the literature on sputtering and blistering, we estimate that an erosion allowance of 0.13 cm for Cu, 0.02 cm for Mo, and 0.004 cm for W has to be incorporated in the beam-dump design