Numerical study of the ionization process and radiation transport in the channel of plasma accelerator

•The sharp increase in the ionization degree and temperature is observed at the ionization front simultaneously with decrease in density and magnetic field.•The sharp acceleration of plasma takes place behind the ionization front due to the Ampere force.•The transonic flow is formed in the accelerator channel.•The radiation coming from the ionization front for the recombination part of spectrum can penetrate deeply in the incoming flow of weakly ionized gas.•The Lyman alpha line brings an essential contribution to the density of the radiation energy and the radiation energy flux in hydrogen plasma. The study of the axisymmetric ionizing gas flows in a channel of the quasi-steady plasma accelerator is presented. Model is based on the MHD and radiation transport equations. The MHD model for a three-component medium consisting of atoms, ions and electrons takes into account the basic mechanisms of the electrical conductivity and heat transport. The model of the radiation transport includes the basic mechanisms of emission and absorption for the different parts of the spectrum. Results of the numerical studies of ionization process and radiation transport are obtained in the approximation of the local thermodynamic equilibrium.