Evaluation of Raman Scattering as a Sensor of Temperature and Molecular Density

Abstract
The performance of the Raman scattering technique for the remote monitoring of temperature and molecular number density in various wind tunnel and engine testing facilities has been experimentally evaluated. Temperature measurements were made by monitoring the pure rotational spectrum of nitrogen and the rotational branch separations of ν2 of CF4 for temperatures in the range 300 to 1000°K. These measurements yielded an average error of 2.6 and 7.6%, respectively, for temperature measurements at pressures near 1 atm. Molecular number density measurements with 20% error could be made at densities as low as 3.5 × 10+22 m−3 by monitoring the 8 ← 6 rotational transition of nitrogen, 3.5 × 10+23 m−3 by monitoring the Q-branch of the fundamental vibrational transition of nitrogen, and 7 × 10+22 m−3 by monitoring the n fundamental vibrational transition of CF4.

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