Negative ion formations and their effects on the electron temperature in CO₂-N₂-He mixture gas discharges

Formation of negative ions and their influence on the electron temperature of a CO₂-N₂-He mixture gas discharge have been studied both theoretically and experimentally. The results show that (i) CO₃^- and O₂^- increase with increasing gas pressure P, while O^- decreases as P increases, (ii) all negative ion densities increase with increasing electron density n_e; (iii) the relation between the electron temperature T_e and the CO concentration in the discharge has been measured and T_e decreases with increasing CO concentration. This implies that T_e, increased by the electron attachment processes, is decreased by the electron detachment processes involving CO molecules. (iv) Experimentally observed T_e agree well with those obtained from present theoretical calculations.