Simultaneous temperature and relative nitrogen-oxygen concentration measurements in air with pure rotational coherent anti-Stokes Raman scattering for temperatures to as high as 2050 K

The accuracy of temperature and simultaneous relative N(2) -O(2) concentration measurements of accumulated as well as of single-pulse rotational coherent anti-Stokes Raman spectra has been investigated in air in the temperature range from 300 to 2050 K. The experimental spectra were taken in a high-temperature oven at atmospheric pressure for a constant oxygen concentration of 20.9% (air). The evaluation procedure is based on the energy-corrected sudden-power scaling law. The agreement of the thermocouple readings with the mean values of the evaluated coherent anti-Stokes Raman spectroscopy temperatures is higher than 50 K and independent of the temperature. The evaluated oxygen concentration is found to be in the range from 20.0 to 21.7% and is also independent of the temperature.