Linewise Raman-Stokes/anti-Stokes temperature measurements in flames using an unintensified charge-coupled device

Abstract

One-dimensional, spatially resolved (linewise), temporally averaged Stokes/anti-Stokes temperature measurements with 200 μm spatial resolution and 6% precision uncertainty are demonstrated in an opposed-jet-diffusion flame of air vs N2-diluted H2 using the Raman-Stokes/anti-Stokes technique. The Stokes/anti-Stokes temperature profile is compared to temperature measurements obtained using all major species'Q-branches and differences between the two sets of results are discussed. In addition, single-pulse, linewise measurements with 710 μm spatial resolution and 19% precision uncertainty are also demonstrated. To the authors' knowledge this is the first report of linewise Stokes/anti-Stokes temperature measurements in flames. Simultaneous measurements of the N2 Stokes and anti-Stokes vibrationalQ-branches are obtained by using an unintensified Charge-Coupled Device (CCD) that is gated by a ferro-electric liquid crystal light valve and/or a low duty cycle optical chopper to suppress detected flame luminosity. This detection system provides increased detection efficiency, dynamic range, and imaged spectral range over an intensified CCD, allowing spatially resolved Stokes and anti-Stokes signals to be imaged onto one detector.