Theoretical Simulation of Positive Corona Discharge in Atmospheric-pressure Air
Corona discharge in atmospheric-pressure air has been the subject of a vast number of theoretical studies for many years. However, a theoretical description of gas breakdown development still has some difficulties due to both a wide range of initial conditions, under which gas breakdown occurs, and the physical mechanisms that are extremely complex for experimental diagnostics and theoretical description. It ts also necessary to note a large number of species and plasma-chemical reactions in the air discharge plasma, which more complicates the numerical calculation of the gas discharge. All described above indicates that the numerical simulation of gas discharge is a very complex problem. The paper presents the results of time-dependent two-dimensional numerical simulation of a positive corona discharge in the tip-to-plane diode configuration filled with atmospheric-pressure air. The simulation was carried out on the basis of the hydrodynamic model of the discharge performed using COMSOL Multiphysics® Plasma Module. The simulation uses a simplified plasma-chemical species and reactions set for an atmospheric-pressure air, considering the process of electron ionization, impact dissociation, attachment and photoionization of the gas. Additionally the photoionization rate coefficient was calculated using the Coefficient Form PDE Interface. Preliminary results shown that the discharge plasma distribution has non-trivial spatial structure at constant applied voltage (Fig. 1). The structure consists of two main areas: the ionization area (“corona glow”) in form of the thin (0.02 – 0.1 mm) jet, and streamer with width of 0.1 – 0.25 mm. Such structure is indirectly confirmed by experimental studies.
