Plasma-surface interaction: Heterogeneous processes of atmospheric gases
Résumé
Surface kinetics plays a central role in many plasma applications ranging from low pressure technological plasmas to plasma-catalyst systems and thermal protection for space re-entry. From the microscopic perspective, heterogeneous reactions in plasmas involve multiple elementary steps (adsorption, desorption, diffusion, recombination) that usually take place on poorly characterized disordered surfaces. Regardless of the great number of works devoted to the study of plasma-surface interactions, the underlying reaction mechanisms are still not fully understood and a lot of uncertainty still remains. In this paper, we summarize our recent experimental studies of the kinetics of adsorption, desorption and recombination of oxygen and nitrogen atoms on dielectric surfaces in contact with low pressure plasmas. Obtained results challenge existing models of atomic recombination on surfaces and stimulate the development of new models. For example, it is found that adsorbed atoms exhibit a distribution of reactivity which has to be taken into account in simulations. We demonstrate that Dynamic Monte Carlo techniques are particularly suited for simulation of heterogeneous processes on realistic disordered surfaces.