Mitigation of carbon erosion in beryllium seeded deuterium plasma under bombardment by argon and helium ions in PISCES-B

The influence of argon and helium impurities on chemical erosion of carbon by deuterium and on the mitigation of erosion by the beryllium seeding has been studied in the PISCES-B linear plasma device. Optical spectroscopy has been used to quantify the amounts of Be, Ar and He in the deuterium plasma and to monitor the reduction of the CD band as a measure of carbon chemical erosion of the fine-grain graphite target. The addition of Ar and He has not resulted in an increase of the carbon erosion rate. Moreover, the characteristic time for the Be layer formation was in agreement with the reference exposures. It can be concluded, that for the covered range of experimental parameters the addition of Ar and He to plasma does not affect the formation of the protective Be carbide layer and the associated mitigation of carbon erosion.