Laser Light Scattering from Equilibrium, High Temperature Gases: Limitations on Rayleigh Scattering Thermometry

摘要

The influence of high temperature chemistry on the accuracy of Rayleigh scattering thermometry of air, carbon dioxide, hydrogen and argon is investigated. Temperature dependent mean elastic scattering cross-sections and intensities are calculated by combining Rayleigh cross-section data for molecules, atoms and ions with equilibrium species molar fractions calculated with the NASA CEA equilibrium chemistry code. Results are presented for the temperature range between 250 K and 15,000 K and pressures from 0.1 bar to 100 bar. The density and temperature measurement errors introduced by dissociation and Thomson scattering are discussed.