Effect of leading radiation on the stability of strong shock waves in gases with an arbitrary equation of state

The effect of leading radiation on the stability of a strong shock wave in an ideal gas with an arbitrary equation of state is investigated. The ionization ahead of and behind the shock front and the radiation are assumed to be in equilibrium. The investigation is carried out in the linear approximation with respect to amplitude for disturbances with a wavelength much greater than the width of the relaxation zones ahead of and behind the shock. The conditions under which the leading radiation has a destabilizing effect on the shock wave are established. It is shown, in particular, that neutrally stable shock waves become unstable. The conditions under which the onset of instability is of the threshold type with respect to the radiation intensity are determined. It is found that the radiation also has a destabilizing effect on stable shock waves, including shock waves in a perfect gas. However, in this case instability can develop only when the disturbances have a wavelength comparable with the width of the relaxation zone. A simple physical mechanism of the onset of instability under the influence of leading radiation is proposed.