Fuel removal from castellated structures by plasma discharges in hydrogen and oxygen

Abstract Removal of a-C:H layers from castellated structures of the ITER-like geometry by glow discharge and electron-cyclotron resonance plasmas in hydrogen and oxygen has been studied. The removal efficiency has been determined for gap widths of 1 and 2.5 mm and sample temperatures of 470 and 620 K. In general, the cleaning is more efficient (i) in oxygen- than in hydrogen-GDC, (ii) in ECR than in GDC, in terms of removal per unit time, (iii) for wider gaps, (iv) at higher sample temperatures, which is more pronounced for hydrogen, (v) at the upper edge of the gap side wall than deeper inside, (vi) at the bottom than at the adjacent side wall of a gap.