Spectroscopic data for the prediction of radiative transfer in CO2-N2 plasmas

The spectroscopic data required for radiative transfer calculations in CO2-N2 plasmas are investigated. For diatomic electronic systems, we extend the systematic approach previously developed in Chauveau et al. [Contributions of diatomic molecular electronic systems to heated air radiation. JQSRT 2002;72:503-30], to the carbonaceous molecules C2, CN, CO, and CO+. The calculated vibrational transition moments are systematically compared to experimental data or other calculations when available. The positions and intensities of the rotational lines have been determined in intermediate a/b Hund's coupling case with up-to-date molecular constants. The other important mechanisms include triatomic (CO2) rovibrational transitions, atomic and ion lines, and continuum radiation. The analysis of the optically thin emission of pure CO2 and CO2(97%)-N2(3%) mixture plasmas at chemical and thermal equilibrium in the temperature range 2000-15 000 K shows a persistence of CO2 IR radiation predominance up to about 3800 K in spite of its small molar fraction. The analysis confirmed the importance of the CO fourth positive system for temperatures between 5000 and 7000 K and of atomic lines above. The contribution of continuum radiation to the optically thin emission is found to be weak. Vibrational Einstein coefficients and Franck-Condon factors of the investigated diatomic molecules are provided as supplementary material and the corresponding rotational line lists are available under request.