Removing of Mixed Coatings by Plasma Discharges

Next generation tokamaks offer the possibility of highly efficient energy generation from the fusion reaction of hydrogen isotopes. In tokamak operation, the core plasma interaction with the wall materials could produce tiles erosion. Redeposition of the eroded materials (C-W-Be) leads to an increase in the allowable tritium load if the coatings are not periodically removed. Amongst removal methods, plasma based techniques employing Ar, H-2 gas have been investigated. Plasma cleaning has been carried out on hydrogenated carbon and carbon-tungsten coatings. It has been shown that at a RF power density of 1.3 W/cm(2) (pressure of 1 Pa), the plasma cleaning was effective in removing the coatings. Details of further work in this research activity will be presented.