Utilizing the Master Equation Model for Non-Thermal Recombination Reactions on a Silica Surface

Catalytic reactions on thermal protection system (TPS) surfaces can contribute significantly to the total surface heat flux, making gas–surface interaction modeling a key aspect of vehicle design. Of particular importance are interactions with atomic oxygen and nitrogen. Oxide surfaces and coatings such as SiO$_2$ enable heterogeneous recombination with incomplete thermal accommodation, producing vibrationally and electronically excited species. Accurately capturing the kinetics and transport of these non-thermal products is critical near sharp leading edges and for the characterization of material catalytic properties in ground-testing facilities. Although significant advances in state-resolved aerothermochemistry have been made over the past decade, these models remain limited to gas-phase processes away from surfaces. This work aims to improve understanding of high-enthalpy air–silica interactions involving surface-catalyzed recombination with incomplete thermalization. We develop a vibrationally resolved master-equation model for gas–surface interactions, informed by molecular-dynamics trajectory simulations, providing capabilities beyond conventional multi-temperature, gas-phase-only approaches.