Pressure-Broadened Linewidths for N2 Coherent Anti-Stokes Raman Spectroscopy Thermometry

Abstract

Coherent anti-Stokes Raman Spectroscopy (CARS) is a nonlinear, optical mixing technique that is being successfully applied as a diagnostic tool in a number of different fields. CARS is particularly well suited for combustion diagnostics because its coherence and high conversion efficiency make it capable of probing the high interference environments characteristic of practical devices. Because N2 is the dominant constituent of air-fed combustion, it has received the most attention for CARS thermometry. The usefulness of CARS has been demonstrated by N2 temperature measurements in a highly sooting diffusion flame, an internal combustion engine, and in liquid-fueled combustors. Single pulse CARS spectra have also been obtained successfully in combustion environments.