An updated set of electron-impact cross sections for CO2: untangling dissociation and application to CO2 with Ar and N2 admixtures

Abstract

This work proposes an updated set of electron-impact cross sections (CSs) for carbon dioxide (CO2) by quantitatively identifying CO2 dissociation within the two electronic excitation channels proposed by Phelps. In particular, the CS with energy threshold at 7 eV is considered with a 15% dissociation branching ratio and is associated with dissociation into O(1D) + CO(X), while the one with threshold at 10.5 eV is used entirely for dissociation into O(3P) + CO(a3Πr). Experimental data on CO2 dissociation rate coefficients at moderate reduced electric field (E/N), CO2 conversion efficiencies at high E/N, and electron transport coefficients for E/N∈[10−2, 103] Td are used to validate the updated set and demonstrate its completeness and consistency over a wide range of E/N. Notably, the updated CS set enables the full coupling between the electron and chemical kinetics, a feature lacking in most existing CS sets. The updated set is applied to study electron kinetics in CO2-Ar and CO2-N2 mixtures, revealing significant modifications in the electron energy distribution function and CO2 dissociation rate coefficient due to mixture composition. The updated CS set is made available at the IST-Lisbon database within LXCat.