A Collisional and Radiative Model of Argon Plasma for Application to Ionization Phenomena Behind a Shock Wave

Abstract

A formulation has been performed for the description of excited-level population-densities and gasdynamic properties in nonequilibrium ionizing argon gas. The energy-level structure of an argon atom is assumed to be composed of six actual levels and higher hydrogenic levels. The ionization and excitation due to atom-atom and atom-electron inelastic collisions, as well as radiative transition including the self-absorption effect, are considered in the model. Applying the collisional and radiative model, calculations have been made for the ionization phenomena of shock-heated argon gas. The results show that the ionization relaxation region behind a shock consists of initial ionization, induction, rapid ionizing and equilibrium parts. Also there are sharp peaks of lower excited-level population-densities in the initial ionization region. The simulations, carried out for line-intensity, show that the self-absorption in lines has a significant influence on line-intensity measurements.