TEMPERATURE-MEASUREMENT BY UV-DEGENERATE 4-WAVE-MIXING

The derivation of temperatures of gas phase media from spectra generat ed by DFWM, induced by frequency scanned narrow linewidth lasers, is b riefly reviewed. The technique of multiplex or broadband DFWM is descr ibed, by which spectra, and hence temperatures, may be obtained by a s ingle shot of a novel broadband ''modeless'' laser. Experimental measu rements of broadband DFWM lineshapes from OH are briefly described and compared with theoretical predictions. Results of temperature measure ments in premixed methane/air flames using broadband DFWM spectra are reported. Systematic errors arising from the effect of absorption are discussed, improvements to and applications of the technique to turbul ent media are briefly considered.