Study of Electron Energy in the Chemistry of the Glow Discharge Plasma in the Novillo Tokamak

The evaluation of the electron temperature, density, and plasma potential in a glow cleaning discharge hydrogen plasma in the Novillo tokamak is presented. The objective was to investigate the plasma conditions allowing the removal of impurities from the vacuum vessel, thus avoiding the formation of other chemical compounds that could remain adhered to its inner walls. The discharges were accomplished through two anodes and one cathode within the 0.07 to 0.2-mbar-pressure interval at a power density in the range of 100 to 900 W/m{sup 2}. The plasma parameters were obtained using Langmuir probes. The results indicated that the electron temperature lay between 3 and 10 eV, the electron density was approximately 10{sup 8} to 10{sup 9} cm{sup -3}, and the plasma potential was in the 10- to 18-V range. The electron energy was in the range of the dissociation energy for most impurities found in the Novillo tokamak.