Numerical simulation of axisymmetric anode spot formation in glow discharge at elevated pressure

A two-dimensional nonstationary fluid model is used to simulate dc elevated pressure glow discharges to describe the growth of the instability near an anode inside a cylindrically symmetric parallel plane surface geometry. This model is based on a fluid description of electron and ion transport coupled with Poisson´s equation. Numerical results for the case of a glow discharge in nitrogen gas are presented. The transition of a radially uniform glow discharge into a state with spots or ring structures is obtained from the two-dimensional simulations without any special initiating perturbation. The influence of diffusion, full current through spot, and volume recombination on the normal current density effect in the near-anode region of the glow discharge has been investigated. The applicability of the similarity principle to the anode spot development processes is analyzed. Prerequisites to the existence of the complex shape current structure in the form of a ring with a central spot are discussed