A fluid-plasma model of diffusion-controlled hydrogen discharges sustained in the field of propagating surface waves is presented in this study. The self-consistent description of the discharge structure achieved provides results for the inter-related variations of the discharge characteristics: the electron concentration n e , the concentrations of the three ionic species (H + , H + 2 and H + 3 ), the concentrations of the two neutral gas components (H and H 2 ), the electron temperature, the power absorbed on average by an electron, the gas temperature, the wavenumber and the space damping rate α of the wave. Wave behaviour in radially inhomogeneous collisional plasmas is taken into account because it provides the proper description of diffusion-controlled discharges. The general mechanism of nonlocal heating of the electrons in the wave field is considered. The model is extended to comparatively low gas pressures (p 0.2 Torr) by introducing effective mobilities of the ions in which, besides the ion-neutral elastic collisions, the production and destruction of ions by collisions are included. Based on these effective mobilities, the ambipolar diffusion coefficients of the charged particles are specified. The most important reactions that contribute-under the gas-discharge conditions considered-to the production of charged particles and hydrogen atoms as well as to the electron-energy and gas-energy balances are involved in the model. It is shown that in hydrogen discharges, the ( -n e )-relation, which besides the (α-n e )-relation ensures a self-consistent description of the axial structure of surface-wave-sustained plasmas, in general, stems from the dependence of on the concentrations of the neutral gas components (H, H 2 ) and their relation to the concentrations of the ions (H + , H + 2 and H + 3 ). The results obtained using the model are discussed in the context of experiments showing a peculiar behaviour of the axial structure of hydrogen discharges compared to discharges in other gases.

A review on recent development in self-consistent description of high-frequency discharges is presented. The discussions are based on fluid models of travelling-wave-sustained plasmas and results for the axial structure of discharges in different gases.

This article presents a fluid-plasma model of the free-fall regime of maintenance of high-frequency discharges in hydrogen. The obtained results are for the radial profiles of the concentrations and the velocities of electrons, positive H+, H2+, and H3+ ions, negative H− ions, potential of the radial dc electric field, and electron temperature. The importance of the directed motion of the charged particles in the radial dc electric field, the negative ion behavior in the discharge, and the description of the discharge characteristics by continuous radial profiles, which smoothly cover the total cross section of discharge, are stresses. A strong impact of the negative ions on the formation of the self-consistent discharge structure is shown. The discussions are in terms of changing gas pressure and electron concentration at the discharge axis.

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In this work we study the effect of an external magnetic field and gas flow on the properties of a low current DC (gliding) arc discharge in argon at atmospheric pressure. We consider a cross flow configuration, in which argon gas flows perpendicularly to the arc current, while the external magnetic field is perpendicular to both the arc current and the gas flow. The study is based on a 2D numerical fluid plasma model of the discharge, coupled with a gas flow model based on the Navier-Stokes equations and a gas thermal balance equation. In the examined configuration, a stabilized arc is achieved by having the E × B drift acting in opposite direction to the gas flow, i.e. the Lorentz force pushing the arc against the gas flow. The numerical model was implemented into a finite element simulation, using the Comsol Multiphysics R (version 5.3) package. The results proved that a magnetically stabilized arc can be sustained and that the examined configuration can be used for effective gas treatment. The analysis of the simulation data helped to answer multiple questions, related to arc stability, the energy density distribution in the arc, and the macroscopic properties of the system as a whole. The results show a significant influence of the walls on the arc stabilization, while in the case of walls positioned very far from the arc, i.e. unbounded channel, the arc becomes a source of a fluid instability, causing vortex shedding. In general, this study provides insight on the interaction between the gas flow and the arc in a strong magnetic field. The model presented here has the potential to further the understanding of magnetically stabilized discharges and to become a basis for developing similar studies of more complex gases.