1ST-WALL AND LIMITER CONDITIONING IN TFTR

A progress report on the experimental studies of vacuum vessel conditioning during the first year of TFTR operation is presented. A quantitative comparison is given on the effectiveness of vessel bakeout, glow discharge cleaning, and pulse discharge cleaning in terms of total quantity of removed carbon and oxygen, residual gas base pressures and the resulting plasma impurity levels as measured by visible, UV and soft X-ray spectroscopy. The initial experience with hydrogen isotope changeover in TFTR is presented including the results of the attempt to hasten the changeover-time by using a glow discharge to precondition the vessel with the new isotope.