A Tightly Coupled Non-Equilibrium Magneto-Hydrodynamic Model for Inductively Coupled RF Plasmas
Journal Article,01 Jan 0001,01 Jan 0001
AFRL/RQRS Edwards AFB United States
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The objective of the present work is the development a tightly coupled magneto hydrodynamic model for Inductively Coupled Radio-Frequency RF Plasmas. Non Local Thermodynamic Equilibrium NLTE effects are described based on a hybrid State-to-State StS approach. A multi-temperature formulation is used to account for thermal non-equilibrium between translation of heavy-particles and vibration of molecules. Excited electronic states of atoms are instead treated as separate pseudo-species, allowing for non-Boltzmann distributions of their populations. Free-electrons are assumed Maxwellian at their own temperature. The governing equations for the electromagnetic field and the gas properties e.g. chemical composition and temperatures are written as a coupled system of time-dependent conservation laws. Steady-state solutions are obtained by means of an implicit Finite Volume method. The results obtained in both LTE and NLTE conditions over a broad spectrum of operating conditions demonstrate the robustness of the proposed coupled numerical method. The analysis of chemical composition and temperature distributions along the torch radius shows that i the use of the LTE assumption may lead to an inaccurate prediction of the thermo-chemical state of the gas, and ii non-equilibrium phenomena play a significant role close the walls, due to the combined effects of Ohmic heating and macroscopic gradients.