Shock-Tube Investigation of the Ionization of Cesium Vapor

Abstract

A conventional pressure‐driven shock tube was used to produce ionizing shocks in a uniformly heated test section containing argon and vaporized cesium. The radiation from the shock‐heated cesium vapor was used to measure the thermal ionization rate of the cesium vapor as a function of temperature and density. A number of significant differences are noted between the results obtained here and those obtained in similar experiments with inert gases. In particular, unlike the inert gases, the luminosity profile of the ionizing cesium shows a delayed radiation overshoot. The overshoot apparently arises from the two‐stage nature of the ionization process, and on the basis of a qualitative model for the ionization, permits an experimental evaluation of the temperature and density dependence of both the first‐stage atom‐atom process and the second‐stage electron‐atom reaction. The results are discussed in terms of the present theories of the ionization kinetics.