Passage of a plane shock wave through the region of a glow gas discharge

The interaction of a plane shock wave (M = 5) with an ionized plasma region formed before the arrival of a shock wave by a low-current glow gas discharge is considered experimentally and numerically. In the experiment, schlieren images of a moving shock-wave structure resulting from the interaction and consisting of two discontinuities, convex in the direction of motion of the initial wave, are obtained. The propagation of a shock wave over the region of energetic impact is simulated on the basis of the two-dimensional Riemann problem of decay of an arbitrary discontinuity with allowance for the influence of horizontal walls. The systems of Euler and Navier–Stokes equations are solved numerically. The non-equilibrium of the processes in the gas-discharge region was simulated by an effective adiabatic index $\gamma$. Based on the calculations performed for equilibrium air ($\gamma$ = 1.4) and for an ionized nonequilibrium gas medium ($\gamma$ = 1.2), it is shown that the experimentally observed discontinuities can be interpreted as elements of the solution of the two-dimensional problem of decay of a discontinuity: a shock wave followed by a contact discontinuity. It is shown that a variation in $\gamma$ affects the shape of the fronts and velocities of the discontinuities obtained. Good agreement is obtained between the experimental and calculated images of density and velocities of the discontinuities at a residual gas temperature in the gas discharge region of 373 K.