Simulation of the layer of non-equilibrium ionization in a high-pressure argon plasma with multiply-charged ions

Deviations from ionization equilibrium caused by diffusion in the near-cathode region of an atmospheric-pressure argon arc discharge are studied. The model comprises the continuity and transport equations for electrons, atoms, and singly-, doubly- and triply-charged ions. A numerical solution of these equations is obtained in a wide range of electron temperatures in the layer. Distributions of densities of the species across the layer and the ion currents to the cathode are presented. It is shown that in the whole range of the electron temperatures the major contribution to the total ion current to the cathode is due to singly-charged ions. A comparison is presented of the obtained numerical results with those given by a model with only singly-charged ions.