A Method for Calculating the Composition of a Heterophase Low-Temperature Plasma with Analysis of CO2 Conversion under the Effect of Gyrotron Radiation

Abstract

Known calculational implementations of the extremum principle of chemical thermodynamics, which are used to analyze equilibrium plasmas, are extended to description of nonequilibrium steady states of a low-temperature plasma (LTP) with the use of a physical model for the excess of energy in partially independent subsystems (electronic and vibrational) with temperatures T_e and T_v relative to T. At a statistical level, we introduce “multitemperature” functions of LTP components, which make it possible, in the framework of the Gibbs energy minimization method, to predict conditions of formation of condensed substances (materials) from the LTP. The simulation results on the composition of a nonisothermal microwave gyrotron plasma in a CO₂ + Ar mixture, with the use of an experimentally determined electron temperature, T_e = 0.7 eV = 8120 K, confirm the 30% CO₂ conversion reached in practice at T = 1900 K; that is, the CO₂ splitting temperature is approximately 700 K lower than that calculated for a thermal plasma. The calculated plasma composition agrees with experimental data, and Ar plasma gas is shown to influence characteristics of the plasma and CO₂ splitting conditions. In addition, the simulation results predict that the CO₂ splitting products contain no condensed carbon.