Experimental study of plasma decay in pulsed microwave discharges of H-2, CH4 and their mixtures

摘要

The results of the experimental investigations of the plasma decay in X-band pulsed microwave discharges produced by surface waves in hydrogen and hydrogen-methane mixtures under pressures of 0.5-5 Torr are presented. The electron density in the decaying plasma was measured by the resonator method using a high-Q quasioptical resonator. These investigations demonstrated a significant influence of ion conversion processes on the composition of ions in a hydrogen-methane plasma. Such conversion processes result in a change in ionization-recombination balance, which, in turn, influences the parameters of the discharge plasma. Ion recharging processes quickly convert the 'primary' H-2(+) ions in hydrogen into H-3(+) ions. It was found that the addition of even a few percent of CH4 to hydrogen, after a sequence of ion-molecular reactions, leads to the formation of complex ions CxHy+. Recombination coefficients and the dominant type of ions in hydrogen and hydrogen-methane plasma are reported.