A novel kinetic model for chemical energy accommodation on silica surface

¹ CIRA, Italian Aerospace Research Center Via Maiorise, Capua 81043, Italy
² UTRC 411 Silver Lane, MS 129-29, East Hartford, CT 06118-1127, USA

Abstract

A new phenomenological catalysis model for silica surface has been developed, the main feature of which is the capability of accounting for chemical energy accommodation (CEA), i. e., the effective transfer of chemical energy to the catalyst surface by catalytically formed molecules. In this new model the interaction time between a just-formed molecule and the surface is compared with the time of other processes, and the efficiency of the interaction depends on the coupling between the molecules interaction time before desorption and the phonon frequency distribution (a characteristic period of surface vibration). These two quantities have been evaluated for the case of oxygen atoms impacting a silica surface. To this aim, a new three dimensional model of the interaction potential between the surface atoms and the impacting atom has been built and utilized inside the bulk structure of crystalline silica. Finally, the model has been validated using data collected during a test campaign in the CIRA SCIROCCO Plasma Wind Tunnel (PWT) on a full-scale aerodynamic spacecraft component.