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

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(a³Π_r). 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.