Experimentally Determined Structure of the Shock Reflection Process in Ionizing Xenon

Abstract

The results of an experimental investigation of the reflection of strong shocks in xenon from the end wall of a shock tube are presented. The reflection of the incident shock structure, consisting of a frozen shock front, a region of relatively uniform frozen flow, and an ionization front, was observed with a fast‐rise (0.3 μsec) pressure gauge mounted in the shock‐tube end wall. The incident shock Mach number was varied from 11‐20, and the initial pressure was varied from 0.1‐1.5mmHg. The interaction between the reflecting shock and the ionizing gas in the incident shock structure produces a complicated series of shock and rarefaction waves; those waves that propagate back to the end wall were observed with the pressure gauge. A simple model which includes the gross features of the shock reflection process is used to calculate end wall pressures. The calculated pressures agree well with the experimental observations. In addition, ionization relaxation times for xenon behind the incident and reflected shocks are presented. The relaxation time data yield a better understanding of the ionization relaxation process in monatomic gases and provide an estimate for the electron‐atom, inelastic cross section for xenon.