The removal of co-deposited carbon/deuterium films from stainless steel and tungsten by transferred-arc cleaning

Deuterium and carbon were co-deposited onto tungsten and stainless steel samples using a deuterium plasma seeded with varying amounts of deuterated methane to simulate carbon-based deposited layers in magnetic-confinement fusion devices. Cathodic arc, or transferred-arc (TA) cleaning was employed to remove the deposits from the samples. The samples were characterized by ion beam analysis both before and after cleaning to determine deuterium and carbon concentrations present. The extent of TA cleaning was varied to determine the deuterium and carbon removal efficiency and sample erosion rate. The deuterium content was greatly reduced by the cleaning, thus demonstrating the possibility of using the TA cleaning technique for removing deuterium and/or tritium from components exposed to D–T fuels. The TA removal of carbon, tantalum and molybdenum contaminants from the same samples was also quantified. Removal of surface layers and significant reduction of subsurface concentrations of these contaminants were observed.