Gas heating and plasma chemistry in low-pressure CO2 plasmas

We develop a self-consistent kinetic model to simulate the evolution of species and energy transfers in low-pressure CO 2 plasmas. This model couples the electron, vibrational and chemical kinetics with the gas thermal balance equation, providing a comprehensive framework for understanding CO 2 plasmas. The kinetic model is thoroughly benchmarked and validated by comparison its predictions with reported simulation and experimental data on CO 2 DC glow discharges, operating at pressures 1–5 Torr, discharge currents of tenths of mA, and tube radius of 1 cm. The results show that the energy released from electronic and vibrational excitation of CO 2 dominates the gas heating at the early stage of the discharge. However, as the discharge progresses and reaches steady-state, following CO 2 dissociation, the de-excitation of electronically excited states of the products and the vibrational-translational exchanges of the CO vibrational state significantly contributes to the gas heating. Additionally, the quenching of excited states at the wall is both a major destruction pathway for these species and a contributor to the gas heating. This study provides a comprehensive perspective to the microscopic reactions and macroscopic parameters in CO 2 plasmas, which can inform optimization strategies for industrial applications. • Benchmarked and validated self-consistent kinetic model for low-pressure CO 2 plasmas. • Updated electron impact cross-sections, plasma chemistry and gas thermal balance. • Energy transfers are mediated by vibrationally and electronically excited states. • CO 2 excited states dominate gas heating at the early instants of the discharge. • CO, O 2 and O excited states contribute significantly to the kinetics at steady-state.