Simultaneous temperature and relative O-2-N-2 concentration measurements by single-shot pure rotational coherent anti-Stokes Raman scattering for pressures as great as 5 MPa

Dual-broadband pure rotational coherent anti-Stokes Raman scattering is a v aluable nonintrusive tool for gas diagnosis that provides simultaneous and time-resolved information about temperature and relative species concentrat ion. A systematic investigation of single-shot precision and accuracy of si multaneous measurement of temperature and O-2/N-2 concentration is presente d. Various O-2 concentrations (1.0-15.6%) in binary mixtures with N-2 have been investigated in a temperature range from 300 to 773 K and for pressure s of 1-50 bars (0.1-5 MPa). A comparison of two least-sum-squared differenc es fit evaluation procedures for the spectral shape, weighted constantly or inversely with respect to the relative signal intensity, is given. The res ults yielded good accuracy and precision for measuring temperature as well as concentration. The influence of temperature, O-2, concentration, pressur e, and evaluation techniques on both accuracy and precision is discussed. ( C) 2000 Optical Society of America OCIS codes: 120.0120, 120.6780, 300.6230 , 300.6420, 290.5860.