GLOW-DISCHARGE WALL CONDITIONING OF TOKAMAK ADITYA

The dc glow discharge wall conditioning (GDC) in hydrogen is an effici ent technique to reduce carbon and oxygen impurities residing on the w all of the vacuum vessel. The efficiency of this scheme depends on the glow discharge plasma parameters and their spatial distribution in th e vacuum vessel. In this paper we present the analysis of the de glow discharge plasma parameters during the wall conditioning of the tokama k ADITYA. We found that the floating potential of the glow discharge p lasma drops with time during GDC indicating the reduction in the effec tive ion mass in the plasma. We also found that the efficiency of GDC is mainly influenced by the electron energy distribution function (EED F) of the glow discharge plasma. Probe analysis revealed that the EEDF is Maxwellian for the anode placed in the center of the vessel while it is non-Maxwellian for the anode placed away from the center.