Non-equilibrium electronic and vibrational kinetics in H2-N 2 and H2 discharges

Abstract

In the first section of this paper, the results from a systematic theoretical study describing the electron kinetics and the heavy particle kinetics of H2 in glow discharges through H2-N2 mixtures are presented. The results show that the collisional interactions between the vibronic states of H2, N2 are highly nonlinear, and that they strongly affect the dissociation, ionization, gas heating, discharge impedance and power loading. It is shown that at low discharge currents (<80 mA), medium gas pressures (>1 Torr), and approximately=10-80%H2-N2 gas mixture composition, quenching of the excited electronic states of N2 by H2 is the dominant dissociation channel of H2 in %H2-%N 2 discharges. The results further demonstrate that the dissociation balance and the electronic/ionization balance in these molecular glow discharges are strongly coupled and that neither can be studied independently of the other. In the second section of this study, a revised kinetic analysis of the formation of atomic H- negative ions in volume sources is presented. A new process for the production of H- is introduced in the analyses. Using data derived from recent experiments, it is shown that the contribution to H- formation from dissociative attachment to the high Rydberg states of H2 is comparable to (or greater than) that from H 2(X1 Sigma g+,V). This additional source term for H- production may resolve some of the problems in understanding the H- densities in low-pressure H2 plasmas.