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Interpretation of the spectral structure of Rayleigh scattered light from combustion gases

Conference ·
OSTI ID:7355029
The determination of the temperature of combustion gases from Rayleigh scattered laser light can be greatly simplified if the effect of Brillouin scattering is assumed to be negligible. To define precisely the regimes in which this assumption is applicable, measurements of the broadening effect of Brillouin scattering on the R ayleigh spectra from nitrogen, oxygen, air and argon have been made with a Fabry-Perot spectrometer. These spectra were analyzed using a trimodal Gaussian model convoluted with the instrument function for the spectrometer. The results of this investigation indicate that if the value of a parameter y, the ratio of the wavelength of the fluctuations producing the scattering divided by 2..pi.. to the collision mean free path, is less than 0.1, Brillouin scattering is negligible. This criterion is shown to be satisfied in the post flame zone of an atmospheric pressure premixed hydrogen air flame.
Research Organization:
Sandia Labs., Albuquerque, N.Mex. (USA); California Univ., Berkeley (USA). Lawrence Berkeley Lab.; California Univ., Berkeley (USA)
DOE Contract Number:
AT(29-1)-789
OSTI ID:
7355029
Report Number(s):
SAND-75-8704; CONF-760102-5
Country of Publication:
United States
Language:
English