On the Stability of Ionizing Shocks in Monatomic Gases

Prior work by our group demonstrates the use of a collisional-radiative model in reproducing the correct steady-state shock structure of ionizing shocks in monatomic gases.\footnote{Le, H. P., et al., Bull. Am. Phys. Soc. \textbf{57}, 17 (2012)} In this presentation, we report on time dependent calculations of ionizing shock flows, which reveal additional physical phenomena arising from the unsteadiness and non-linear wave coupling between convection and kinetics. The observed phenomena are similar to instabilities often seen in gaseous detonations.\footnote{Cole, L. K., et al., Combust. Sci. Technol. \textbf{184}, 1502-1525 (2012)} The present model also takes into account radiative heat losses and radiation transport, which result in a reduction in the shock velocity and precursor effects. The latter phenomena may be important at high shock velocities, and are being investigated in detail.