Kinetic processes in dusty plasmas produced by shock wave

Summary form only given: Upper and middle atmosphere contains different kinds of ions, clusters, and nanoparticles. Shock waves forming in the air over the vehicles crossing the upper and middle layers of the atmosphere with a hypersonic velocity or produced by atmospheric electrical discharges and explosions induce the fast nonequilibrium processes in high temperature plasma behind the shock front. In the most cases the processes in such high temperature plasma are far from being equilibrium. However, up to now in modern studies there is no quantitative information about possible effects of the abundance of clusters and nanoparticles in plasma behind the shock and plasma surrounding the hypersonic vehicle. This paper is focused on the analysis of the influence of cluster and nanoparticle abundance in a flow behind the shock on the plasma properties. The comprehensive analysis of nonequilibrium processes involving formation of excited atoms and molecules, ions and electrons as well as charging of clusters and particles in dusty plasma produced by air shock wave is conducted. The different modes of charged particle formation behind shock wave are considered. The analysis based on the novel physicochemical model, which was validated against the experimental data on the concentration of electrons behind strong shock wave, showed that clusters and nanoparticles which are present in the ambient atmosphere or form due to ablation and erosion of vehicle surface protection may acquire a significant negative charge in a shock layer due to attachment of electrons and ions to particles. There exist two principally dividing regimes of dusty plasma appearance. At relatively low temperature in the post shock region (Tles2000 K), when the particle thermal relaxation time is significantly smaller than the characteristic time of chemiionization reactions, the thermoemission of electrons is responsible for charged species production. At high temperature in the post shock region (Tges- - 2500 K) the particle thermal relaxation time is markedly larger the time of ion formation chemiionization reactions. In this case, particle charging occurs due to particle-ion (electron) interaction. The quantity of the charge accumulated by particles strongly depends on the particle size, particle number density, and shock wave intensity. Particle-electron (ion) interaction may considerably influence the concentration of electrons and ions and consequently electroconductivity of dusty plasma forming in the post shock region.