A general setup for gas-temperature measurement by spectrum-line reversal

A general scheme of gas-temperature measurement by spectrum-line reversal, where the angular apertures of the radiation fluxes from the heated gas and the reference source need not be equal, is described. The method of calculating the corresponding apertures is described. The apertures can be altered by means of plane slits. The method was tested in experiments in which the temperature of a gas mixture (0.15 CO2 + 0.85 N2), heated in an incident shock wave, was measured. Chopping of the light flux of the standard source was used to measure all the required parameters in the same experiment. The gas temperatures measured by this method, whose accuracy was estimated as 5%, agreed with the values obtained by calculation from the shock-wave velocity on the basis of the laws of conservation of the flux densities of mass, momentum, and energy.