Experimental progress on chemical erosion of graphite bombarded by deuterium ion beam

A development study, based on the basic study of chemical sputtering of graphite bombarded by a deuterium ion beam, was carried out with fresh SMF-800 graphite, G3 graphite, SiC and boronized graphite, etc. The SMF-800 graphite boronized in situ in the HL-1M tokamak with carborane (C2B10H12) by helium glow discharge was selected as the best one for anti-chemical-erosion. It possesses a releasing rate of CD4 which is one order of magnitude lower than that of SMF-800 graphite and a releasing peak temperature of CD4 shifts to 650 K. By rotating the graphite sample with a small angle, a profile of CD4 releasing from the sample bombarded by a deuterium ion beam of 1.3 μA/3 keV was observed. With 45 degree incidence of the beam from left side, the releasing CD4 peak was positioned at the right side 1 degree from the sample's normal. The releasing rate of CD4 at a 5 degree deviation from the normal was decreased by 7% approximately, a change one order of magnitude faster than the cosine law