Plasma chemistry of RF discharges in CO2laser gas mixtures

Abstract

The authors have used mass spectrometry to investigate the changes in the composition of the molecular species in radio frequency excited discharges in typical waveguide laser CO₂-N₂-He(H₂O) mixtures and discharge conditions. The initial rate of dissociation of CO₂ is approximately 10-90% in approximately 1 s: final dissociation levels are determined by back reactions with water vapour. The dissociation increases with power but is independent of frequency (29-200 MHz). Comparison of the flowing discharge and afterglow environments shows considerable differences with large amounts of the oxides of nitrogen and radical species present in the former.