MEASUREMENT AND MODELING OF N-ATOM BEHAVIOR IN THE AFTERGLOW OF A MICROWAVE PLASMA

Nitrogen-atom behavior in a low-pressure, nonisothermal microwave-gene rated nitrogen afterglow was studied. N-atom flux was measured by chem ical titration. It was found that an increase in power or flow rate, o r a decrease in pressure resulted ill larger productions of N atoms. A one-dimensional mass-continuity equation was used to model N atoms' c oncentration field in the afterglow. The model, with no adjustable par ameters, agreed closely with experimental measurements. The model show s that convection, diffusion, and wall recombination play important ro les in the afterglow. In contrast, N-atom generation and homogeneous r ecombination are of marginal importance. The model was manipulated to assess the impact of the measuring technique, chemical titration, on t he N-atom flux. It was found that the N-atom flux profile is only slig htly impacted, although the concentration profile is strongly modified .