Removal of carbon layers by oxygen glow discharges in TEXTOR

Glow discharge cleaning (GDC) in mixtures of O2 and He was applied in TEXTOR for about 4 h to study the removal of redeposited carbon layers. The behaviour of the formation of volatile carbon oxides (CO and CO2) and its dependence on the O2 injection rate and on the addition of He into the O2 GDC are described. Carbon (5.22 g) was removed from TEXTOR in about 4 h GDC corresponding to a carbon removal rate of ∼2.1 × 1019 C/s. Plasma recovery was obtained after wall cleaning in H2 GDC and finally by boronisation.