Influence of vibrational nonequilibrium on electron creation and loss kinetics in high pressure molecular plasmas

Ohio State University Research Foundation -Do Not Use, Columbus OH

Investigators

Abstract

This project focuses on the study of basic kinetic processes in strongly non-equilibrium, high-pressure molecular plasmas. Unlike ordinary thermal plasmas, which are formed by simply heating a gas to high temperature, non-equilibrium plasmas are formed by the input of energy into specific internal energy states, in this case, molecular vibrations. This provides a unique plasma environment in which the degree of ionization is significant, yet the temperature is quite low (order room temperature). This low temperature enables a wide variety of practical engineering devices and processes including, to name only a few, plasma chemical reactors, pollution control systems, and molecular lasers. However, achieving the full commercial and/or military potential of such high pressure non-equilibrium plasma-based systems requires that the overall input power be reduced by at least one to two orders of magnitude below that presently required. Fundamentally, the power requirements are high because the rate at which electrons are dissipated in the plasma, by recombination with positive ions and/or attachment to neutrals is quite rapid, particularly in the presence of oxygen. The traditional approach for overcoming this rapid loss of electrons is to increase the input power, in order to increase the rate at which electrons are produced. The goal of this study, however, is to explore kinetic mechanisms for reducing the rate of loss. Specifically, experimental measurements will be performed in an crossed electron-beam / CO laser non-equilibrium plasma generation apparatus, and will feature utilization of a full suite of diagnostic and computational tools, including a high sensitivity spectrally filtered Thomson scattering instrument for determination of spatially and temporally resolved electron density and temperature. This project is jointly funded by the Physics Division in the Mathematical and Physical Sciences Directorate and by the Chemical and Transport Systems Division in the Directorate for Engineering.