Instrumentation for Raman/Rayleigh light scattering measurements of gas densities and temperatures in aerospace test facilities

Instrumentation systems have been developed for the measurement of gas species densities and temperatures in a variety of flow situations in aerospace test facilities. These are nonperturbing, time-resolved measurements and utilize the Raman/Rayleigh light scattering technique. The system has been used in both laboratory and test facility environments, including such complex flow situations as radiating rocket plumes immersed in supersonic air flow. The paper presents a brief description of the technique, the details of the instrumentation systems, the application requirements and the interconnection of the respective components. Depending upon the experimental measurements, both conventional and Q-switched laser modes are used. In all cases the minicomputer serves as a media for data input and control functions for lasers, spectrometers, photon counters, etc., and data monitor and display devices. The experimental results have agreed well with theory and other diagnostic measurements. Some anticipated future applications, proposed system improvements and new instrumentation techniques are discussed for various gas dynamic applications.