HIGHLY EXOTHERMIC SURFACE PROCESSES RELEVANT TO THE TPS TILES: OXYGEN ATOM ADSORPTION ON BETA-CRISTOBALITE AND BETA-QUARTZ

The paper focuses on the dynamics and energetic of the adsorption and adsorption/desorption processes of O atoms on two silica polymorphs, beta-cristobalite and beta-quartz at high temperature. Interestingly, we clearly report for the first time that the energy transferred to the two silica surfaces is high, particularly in multi-step adsorption collisions. These heterogeneous processes can be considered of great relevance for the heat shield of space shuttles used in planetary exploration missions.