Experimental Measurements and Mechanism Optimization Research on Dissociation of High-Temperature CO2

Carbon dioxide undergoes rapid dissociation during high-speed entry into the Mars atmosphere. This process is closely related to the heat transfer on the surface of a spacecraft. A precise quantitative characterization of this nonequilibrium process is critical for accurate aerodynamic heating predictions. A [Formula: see text] tunable diode laser absorption spectroscopy ([Formula: see text]-TDLAS) was developed and coupled to the previous CO-TDLAS system for simultaneous temperature, CO concentration, and [Formula: see text] concentration measurements during the [Formula: see text] dissociation process. The R(0, 88) line in the [Formula: see text] fundamental vibrational band was selected, and its absorption cross section was calibrated over 3030–5990 K. The new setup was then applied to studies of [Formula: see text] dissociation behaviors. Evident deviations were found between measurements and model predictions. Sensitivity analysis was performed to find out the key reaction impacting [Formula: see text] dissociation and to suppress the impacts of secondary reactions. The reaction rate coefficient of [Formula: see text] was updated as an Arrhenius equation over 2980–6030 K. The revised mechanism with updated rate coefficient predicts more accurate [Formula: see text] dissociation behaviors over 3000–6000 K. In addition, this study provides a functional methodology to determine the rate coefficient of a specific elementary reaction over a wide temperature range with low uncertainty.