Modelling dc glow discharges in a wide range of currents with Comsol Multiphysics. New results, fortes and weaknesses

Modelling of a DC glow discharge in a wide current range is performed by means of a steady-state solver of commercial software Comsol Multiphysics. Two discharge models are treated: the basic model of glow discharges and a detailed model which takes into account atomic and molecular ions, atomic excited states, excimers, and non-locality of electron energy. Complex behaviour of the discharge was found in two different situations: in the framework of the detailed model in a parallel-plane discharge and in the framework of the basic model in a cathode boundary layer discharge. This behaviour is manifested through a retrograde section limited by two turning points. Being very interesting by themselves, the results illustrate suitability of Comsol Multiphysics for modelling DC glow discharges in a wide current range, but also reveal unfortunate limitations of this powerful tool. 1