Kinetics of a recombination nonequilibrium He–H2 plasma in a beam-type discharge

Calculations were made of the kinetics of a transient He–H₂ plasma excited by an electron beam formed in a discharge. The kinetic plasma relaxation model took into account 155 plasma-chemical reactions. An analysis was made of the time dependences of the plasma parameters, the concentrations of the 3 ³S and 2 ³P active levels, and the specific output power due to the λ = 706.5 nm He transition at pressures of 8 and 15 Torr in an He:H₂ = 2:1 mixture and pump frequencies of 100 and 200 s ^– 1. The main mechanisms determining the population of the active levels and their temporal dynamics were identified. A comparison between the results of the calculations and the experimental data showed that the population inversion and lasing conditions agree with the model of a plasma recombination laser with the Penning depopulation of the lower active levels.