Two-Dimensional Model of a Direct Current Glow Discharge:  Description of the Electrons, Argon Ions, and Fast Argon Atoms

To improve the analytical results of techniques that use the glow discharge as spectroscopic source, a good insight into the glow discharge is desirable. This can be obtained by mathematical modeling. In this work, a two-dimensional model is developed to describe the electrons, argon ions, and fast argon atoms in a direct current glow discharge in argon. The model consists of a Monte Carlo model for the fast electrons, a Monte Carlo model for the argon ions and fast argon atoms in the cathode dark space, and a fluid model for the argon ions and slow electrons. Results in two dimensions are presented for a standard flat cell of the VG 9000 glow discharge mass spectrometer (VG Elemental, Fisons); they include the densities, mean energies, and collision rates of the plasma species, the potential distribution, and the axial and radial electric fields.