Infrared emission spectroscopy of CO2 at high temperature. Part I: Experimental setup and source characterization

An experimental setup is developed to analyze infrared emission of CO2 plasmas at atmospheric pressure and temperatures up to 5000 K. A microwave discharge is used to produce the hot gas mixture and emission is recorded by a Fourier transform spectrometer with a spectral resolution between 0.01 and 0.1 cm−1. The plasma is confined inside quartz or sapphire tubes which perturb the measurements through refraction, reflection, absorption and emission. We present in this part the experimental setup, an analysis of tube effects, and the characterization of the plasma in terms of temperature and molar fraction distributions using CO emission in the overtone vibrational bands Δv=2. Analysis of the measurements of CO2 emission in the 2.7μm and 4.3μm regions, and comparisons with calculations using different spectroscopic databases are given in the companion paper (Depraz et al., in press) [1].

► A microwave plasma torch is associated with a FTIR spectrometer to measure CO2 emission up to 5000 K. ► The local temperature is deduced from measured CO overtone emission spectra and Abel inversion. ► Refraction, reflection, absorption and emission by confinement tubes are analyzed. ► Mixture composition is confirmed by comparisons of absolute CO emission levels.