CALCULATION OF THE POPULATION-DENSITY IN THE LOW-PRESSURE MERCURY-ARGON DISCHARGE - ANALYSIS OF THE STEADY-STATE AND SINUSOIDAL OPERATING MODES OF THE POSITIVE-COLUMN

This work deals with the setting up of a collisional-radiative model c oncerning low pressure mercury-argon discharge operating under differe nt power supplies (dc and ac). This model allows determination of vari ous characteristic quantities of the discharge using the population an d electronic energy conservation equations. In view of optimisation of the consuming computer time, some simplifying but still realistic hyp otheses have been assumed. A first study in the frame of the steady st ate (dc), allows us to evaluate the << weight >> of certain physical p henomena in this type of modelling. We assess how much it is of prime importance to consider Hg-Hg collisions as well as the excitation and ionization of argon in discharge plasmas. The first point, often disca rded by many authors, has however a quite appreciable influence on the different discharge parameters. Besides, the determination of the esc ape factors for the Hg resonance lines at 254 nm and 185 nm are not fo r the least insignificant.