Abstract:
The effects related to the effect of an external constant magnetic field on weak and strong discontinuities in gaseous media with finite electrical conductivity are discussed. The effect of an external magnetic field on the stability of a plane ionizing shock wave is analyzed in detail. It is shown that there may be two independent mechanisms leading to instability. One, related to the features of the Hugoniot adiabat, can lead to structural instability. In these cases, even at small values of the interaction parameter, the region of stability expands due to the entry into it of the region of neutral oscillations. For a strong shock wave $($Mach number $\rm M_1 \ge 1)$, the region of neutral oscillations of the shock wave, which exists in a medium without a magnetic field, narrows with the increasing magnetic field and degenerates into a point. If the interaction parameter exceeds the critical value, then the stability region narrows. The second type of instability, not related to the features of the Hugoniot adiabat, is caused by the perturbation of the Ampere force and the temperature dependence of the electrical conductivity $\sigma_2(T_2)$. This is a well-known plasma instability that can develop at large values of the interaction parameter in strong shock waves and lead to the generation of a secondary shock wave in a heated gas. The effect of a magnetic field on the structure of a plane ionizing shock wave is demonstrated, including a medium with infinite electrical conductivity, when the intrinsic magnetic field must be taken into account. The derivation of the boundary condition for the electric current in the problem of shock wave stability in a transverse magnetic field is given.
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