Numerical Simulation of Chemical Reactions on Rarefied Plasma Plume by DSMC Method

Chemical reactions in a rarefied plasma plume greatly influence the spatiotemporal distribution and transport characteristics of the flow field. In this article, such chemical reactions are studied using a direct simulation Monte Carlo method. Five particles, including molecular hydrogen H ₂ , atomic hydrogen H , atomic metal X , H ₂ ⁺ ions, and H ⁺ ions, are injected from the sidewall of a cylinder. The chemical reaction network includes H ₂ dissociation/recombination in the bulk and on the solid boundaries, and ion recombination on the wall. First, H ₂ dissociation and H recombination are studied—the rate of H ₂ dissociation is faster than the rate of H recombination. Second, chemical reactions involving H ₂ ⁺ , H ⁺ , and H , on the wall, are studied based on the foregoing study—the number densities of H ₂ ⁺ and H ⁺ are significantly reduced after the chemical reactions on the wall, otherwise the number densities of H ₂ and H are increased. This variation greatly influences the spatiotemporal distribution of the flow field.