Abstract:The possibility of the unified description of kinetic, hydrodynamic and reaction cliffusion processes is considered. The generalized kinetic equation consists of three dissipati ve "collision integrals" :
Low-pressure planar microwave plasmas exhibit a pronounced spatial structure. If the discharge vessels are wide enough, they have a thin, plane homogeneous excitation region adjacent to a microwave coupling window, and they strongly decay in the direction normal to the window. The decay length of plasma parameters and activated neutrals differ by about one order of magnitude. This suggests a two-region approach for modeling of neutral particle kinetics assuming spatial homogeneity inside these two regions. The gaseous reactor volume is subdivided by a virtual interface on which mass exchange by directed gas flow, local microconvective mixing or diffusion, and exchange of enthalpy between the two different regions can be balanced. The main differences between the two regions are that electron-induced generation of activated neutrals is restricted to the excitation region (1) and that basic loss processes for activated neutrals due to the substrate surface and volume reactions are considered to occur in the second, chemical reaction region (2). Processes of loss of active neutral atoms by recombination at inert surfaces of the vessel are considered in both regions. Effectively, the model represents a system of two-coupled continuous flow stirred tank reactors given by a set of differential equations including unsteady-state Bernoulli equations. For the case of an example process concerning an oxygen plasma surface treatment, numerical solutions for initial values at the startup of the reactor are computed. The results for the dynamical behavior and the steady states of the concentrations, the temperatures, and the mass loss are in qualitative agreement with the experimental behavior of a real reactor arrangement.
Low-pressure planar microwave plasmas exhibit a pronounced spatial structure. If the discharge vessels are wide enough, they have a thin, plane homogeneous excitation region adjacent to a microwave coupling window, and they strongly decay in the direction normal to the window. The decay length of plasma parameters and activated neutrals differ by about one order of magnitude. This suggests a two-region approach for modeling of neutral particle kinetics assuming spatial homogeneity inside these two regions. The gaseous reactor volume is subdivided by a virtual interface on which mass exchange by directed gas flow, local microconvective mixing or diffusion, and exchange of enthalpy between the two different regions can be balanced. The main differences between the two regions are that electron-induced generation of activated neutrals is restricted to the excitation region (1) and that basic loss processes for activated neutrals due to the substrate surface and volume reactions are considered to occur in the second, chemical reaction region (2). Processes of loss of active neutral atoms by recombination at inert surfaces of the vessel are considered in both regions. Effectively, the model represents a system of two-coupled continuous flow stirred tank reactors given by a set of differential equations including unsteady-state Bernoulli equations. For the case of an example process concerning an oxygen plasma surface treatment, numerical solutions for initial values at the startup of the reactor are computed. The results for the dynamical behavior and the steady states of the concentrations, the temperatures, and the mass loss are in qualitative agreement with the experimental behavior of a real reactor arrangement.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.