Modeling Nonlinear Coupling between Plasma, Electrodes and Walls for High-Pressure Hg Arc Discharge Lamps

Abstract

This paper presents a model able to give a global description of the functioning of high‐pressure Hg arc discharge lamps, with operation in the diffuse cathode mode. For computational simplicity reasons the lamp is fed on d.c. voltage. The nonlinear interactions between different zones (positive column, electrodes and walls of the discharge tube) is considered through Neumann‐Dirichlet mixed boundary conditions at interfaces. We take into account the nonlinearity of physical characteristics of the electrode material and of the silica envelope. Waymouth's measurements are used for the ratio between electron and ion currents. The temperature profile index as function of the z‐coordinate is determined in the vicinity of the cathode.