Deposition/erosion and H/D retention characteristics in gaps of PFCs in KSTAR studied by cavity technique

Abstract Stainless steel coupons with cavity structure were installed at different poloidal locations in KSTAR during 2009 campaign to study deposition and H/D retention inside the gap of PFCs. The deposition profiles at different poloidal locations indicate that the incoming species have high surface loss probability ( β ) and they are probably charge exchange neutral particles. The (H + D)/C ratios of layers inside the coupons were in a range from 0.04 to 0.37 at different poloidal locations which might be caused by different contribution of different hydrocarbon species. Campaign integrated, time averaged net C, H/D atom flux density towards outer walls are in the similar range with other carbon dominated machines.