The theory of ionizing shock waves in a magnetic field. Part 2. Transverse, normal and switch-off shock waves and the piston problem

Abstract

Solutions for transverse, normal and switch-off ionizing shock waves have been obtained on the basis of the general theory of ionizing shock waves in a magnetic field presented in part 1. Some details of the shock structure were considered at Pm → 0. In particular, the transition from the gasdynamic to the magnetohydrodynamic regime, while increasing the shock velocity, is traced in detail. The additional relationship, obtained in part 1, determines the value of a transverse electric field ahead of the front for the case of a transverse shock wave and for normal and switch-off shock waves, if the latter are shock waves of type 3. In the case of normal and switch-off shock waves of type 4, basic relationship obtained in part 1 is not a boundary condition, but determines the position of a viscous isomagnetic jump in the shock structure. The transition of ionizing shock waves from the GD to the MHD regime, while increasing the shock velocity, was considered. The width of such a transition on shock velocity scale depends significantly on the intensity of precursor photo-ionization. In particular, this transition occurs slowly at zero precursor photo-ionization: the electric field ahead of the front tends to zero as l/vxo when vxo increases. The problem of formation of ionizing shock waves ahead of a magnetic piston and a conducting piston with a magnetic field directed along the normal to the piston surface has been solved. We indicate the set of flow parameters, for which Chapman-Jouguet's model of ionizing front motion ahead of the piston is inapplicable. A transition from the Chapman-Jouguet regime to the MHD one is considered.