THE ANALYSIS OF THE PRECISION OF SINGLE-SHOT 2-LAMBDA-CARS TEMPERATURE-MEASUREMENTS IN HYDROGEN

The results of the experiments on the precision of two-wavelength rota tional CARS thermometry (2 lambda-CARS thermometry) of hydrogen are pr esented. The temperature was determined in a heatable sample cell in t he range 300-1100 K and at pressures 1-25 bar was determined by using the measured values of single-shot and averaged CARS energies for the rotational transitions of the S branch. CARS beams were generated by u sing in turn three types of Stokes laser, with different spectral prop erties. A second cell, also filled with hydrogen, was established to o btain the reference signals. Relative standard deviations similar to 1 .5% at 296 K and similar to 8% at 1000 K were achieved for temperature values measured in single laser shots. The precision of the measureme nts at different spectral characteristics of the pump lasers, linewidt hs of the probed Raman transitions, and referencing conditions, with v ariations in pressure and temperature in the sample volume, is analyze d and possibilities for its enhancement are discussed.