Influence of a random nature of light on a possibility of realization of single-shot high-resolution lineshape spectroscopy
is discussed. Non-linear interaction of light with matter in CARS process could change initial light statistics. Broad band
CARS with use of conventional dye lasers as a source of Stokes waves conserves the initial <<exponential>> light statistics
peculiar to broadband radiation with modes structure. Dual Broad Band CARS-approach can change light statistics from
<<exponential>> in Stokes wave to <<normal>> in anti-Stokes radiation providing the possibility to realize the single-shot high-resolution lineshape spectroscopy.
By means CARS interferometric lineshape spectroscopy the temperature dependences of broadening coefficients for
several Q-branch transitions of hydrogen molecules under collisions with water molecules were determined at
temperature range 2100
We demonstrate the feasibility of the proposed new approach to CARS thermometry of hydrogen-containing mixtures
with simultaneous measurement of the intensities of a hydrogen spectrum Q-branch lines and their linewidths in a single
laser shot by means of a spectrograph combined with an interferometer, that have orthogonal directions of dispersions.
This provides correct temperature evaluation that takes into account the linewidths, measured directly. The experiments
were carried out in a H2:N2 = 1:10 mixture in a heated cell at a temperature of 1050 K. The values of gas mixture
temperature, that were defined in a pressure range of 2-9 MPa from DBB CARS spectra taking into account linewidth
corrections, coincide with a thermocouple measurements within ~ 2 %. Without these corrections the discrepancies
increase up to 5 %. The proposed approach can be applied to CARS thermometry in the course of investigations of H2
and hydrocarbon combustion without the necessity to measure species concentrations, and does not require the
knowledge of the line-broadening coefficients.
The possibility is considered of restoring the electron energy distribution function (EEDF) in the interval of electron energies 0 < e < 5 eV from measurements of translational and vibrational temperatures by the coherent anti-Stokes Raman scattering (CARS) method in a positive column of a glow discharge in molecular nitrogen at 20
Diagnostics of gas mixtures with fluctuating temperature, density and concentration composition requires simultaneous detection of spectra of all species of a mixture with subsequent its joint treatment. Strategy of processing of experimental data, obtained at diagnostics by methods of a spectroscopy of Coherent Anti-Stokes Raman Scattering, is considered. An experimental approach to a performance of density numbers measurements in three-component mixture of O2, H2, H2O in a flame of oxygen-hydrogen burner is presented.
Dual-broadband coherent anti-Stokes Raman spectroscopy (CARS) of the Q-branch of H2 has been employed for thermometry in a laboratory atmospheric pressure hydrogen-oxygen flame. The aim was to investigate the applicability of the technique for single-shot temperature evaluation, to estimate its sensitivity and to analyze the accuracy of the measurements. The results are presented of single-shot temperature mapping of the flame in the temperature range of 700 - 3200 K. The achieved accuracy of single-shot measurements was 3 - 5%.
In this work we present the results of two-wavelength rotational CARS thermometry (2(lambda) -CARS thermometry) of hydrogen at temperatures from 300 K to 1100 K. Experimentally, temperature was measured in a heated cell using single-shot and averaged CARS intensities in the rotational S-branch. Relative standard deviation for single-shot temperature values was approximately 1.5% at 296 K and approximately 8% at 1000 K. The accuracy achieved, its dependence on measured temperature, and possibility of their improvement were analyzed.
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