The structure of radiative shock waves

We consider the structure of steady–state radiative shock waves propagating in partially ionized hydrogen gas with density $\rho_1 = 10^{-10}~{\rm gm}~{\rm cm}^{-3}$ and temperature $3000~{\rm K}\le T_1\le 8000~{\rm K}$. The radiative shock wave models with electron thermal conduction in the vicinity of the viscous jump are compared with pure radiative models. The threshold shock wave velocity above which effects of electron thermal conduction become perceptible is found to be $U_1^*\approx 70~{\rm km}~{\rm s}^{-1}$ and corresponds to the upstream Mach numbers from $M_1\approx 6$ at $T_1=8000~{\rm K}$ to $M_1\approx 11$ at $T_1=3000~{\rm K}$. In shocks with efficient electron heat conduction more than a half of the hydrogen atoms are ionized in the radiative precursor, whereas behind the viscous jump the hydrogen gas undergoes the full ionization. The existence of the electron heat conduction precursor leads to the enhancement of the Lyman continuum flux trapped in the surroundings of the discontinuous jump. As a result, the partially ionized hydrogen gas of the radiative precursor undergoes an additional ionization ($\delta x_{\rm H}\lesssim 5\%$), whereas the total radiave flux emerging from the shock wave increases by $10\%\le\delta(\vec{F}_{\rm R})\le 25\%$ for $70~{\rm km}~{\rm s}^{-1}\le U_1 \le 85~{\rm km}~{\rm s}^{-1}$