Comprehensive study on plasma chemistry and products in [formula omitted] pulsed discharges under Martian pressure

Abstract

With the development of Mars exploration, the In-Situ resource utilization on Mars has been drawn significant attention in recent years. The abundant CO2 in the Martian atmosphere makes it possible to decompose CO2 to produce high-value platform chemicals by plasma technology. In this comprehensive study, the discharge characteristics, products distribution, and reaction pathways in CO2 pulsed discharges under Martian pressure are investigated, and the effects of pulsed waveforms on discharge characteristics and produced species are also discussed. The simulation results show that electrons and CO2+ ions are the main components of charged particles in the discharge region; CO and O are mainly produced by the electron impact dissociation and electron impact attachment reactions with ground state and vibrationally excited state of CO2 during the power-on phase and consumed by the ion–neutral reactions. The recombination reaction of electrons and CO2+ ions is very important for the formation of O2. The simulation data also give the main generation and consumption pathways of vibrationally excited CO2 molecules, and indicate that the vibrational energy of excited CO2 molecules can lower the energy barrier of the reaction and facilitate the decomposition of CO2. In addition, the experimental and computational data also suggest that the pulsed waveforms could affect the discharge characteristics and plasma chemistry in CO2 pulsed discharges under Martian pressure, the densities of product species in CO2 plasma increase with the pulse rise rate and pulse rise duration of pulsed voltage. This study provides an enhanced understanding of discharge characteristics and plasma chemistry in the CO2 pulsed discharges under Martian pressure, and suggests optimized ways to utilize the CO2 on Mars.