Nanosecond Resolved CO₂/N₂ Vibrational Kinetics in a Pulsed Discharge Investigated Experimentally and by Modeling

The vibrational kinetics of CO₂ and CO₂/N₂ mixtures are crucial for the efficient CO₂ dissociation, a key step in CO₂ conversion. A thorough understanding of the vibrational kinetics is required to enable an efficient dissociation but is challenging due to the numerous states and reactions involved. In this study, a ns-pulsed atmospheric pressure plasma jet in CO₂/N₂ mixtures is studied, allowing a temporal separation and thus independent study of the different energy transfer processes. The densities of rovibrationally excited states of CO₂ are measured with ns-resolution using quantum-cascade-laser absorption spectroscopy (QCLAS). The experimental results are compared to a state-of-the-art kinetic model developed in the LisbOn KInetics (LoKI) simulation tool. The comparisons partially validate the model but also reveal that some excitation and energy transfer processes are not reproduced well by commonly used scaling laws. Further, there may be a need to include additional processes and effects.