Deposits removal and hydrogen release on co-deposited films exposed to O-ICR and O-GDC plasmas in HT-7

A few new results of oxidation wall conditionings for deposits removal and hydrogen release were directly obtained on exposure of co-deposited films to O-ICR or O-GDC plasmas in HT-7. After the O-ICR or O-GDC treatments, the deposits were partially removed and deuterium retention was reduced. D ₂ release from samples was reduced by a factor of 2-3, and the ratio of D/C decreased whereas that of O/C increased. The removal rates of C in various oxidation wall conditionings were about 10¹⁸-10¹⁹C m^-2 min^-1, which approached the estimated carbon deposited rates, of about 5.2 × 10¹⁸C m^-2 min ^-1, on the tested samples. The He/O-ICR was more effective on the deposits removal and hydrogen (deuterium) release than O-GDC. And O-ICR was more effective on the surface facing main plasma than on that facing SOL plasma, whereas O-GDC possibly has uniform effectivity on both tested surfaces.