Quantitative effects of ionic excitation and radiation

Abstract. We study the quantitative effects of excitation, ionization, radiation energy and pressure, on the jump conditions in hypersonic shocks in a real gas. The ionization structure and excitation energies are calculated from the local temperature and density, using the Screened Hydrogenic Model. We assume an optically thick medium and no radiation flux through the shock front. We investigate the jump conditions in different gases and propose a phenomenological description of compression for different shock velocities. We find that the excitation energy term is the dominant term in ionized gases at low velocities. Consequently, higher shock velocities than the values predicted by standard calculations in a perfect gas must be reached in order to observe the effects of radiation in the compression ratio. Our results provide constraints for the design of future radiative shock experiments on the next generation of powerful nanosecond lasers or on Z-pinches. PACS. 52.35.Tc Shock waves and discontinuities – 95.30.Dr Atomic processes and interactions