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

(Received 26 May 1992, revised 13 January 1993, accepted 20 January 1993)

Abstract
This work deals with the setting up of a collisional-radiative model concerning low pressure mercury-argon discharge operating under different power supplies (dc and ac). This model allows determination of various characteristic quantities of the discharge using the population and electronic energy conservation equations. In view of optimisation of the consuming computer time, some simplifying but still realistic hypotheses have been assumed. A first study in the frame of the steady state (dc), allows us to evaluate the "weight" of certain physical phenomena 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 discarded by many authors, has however a quite appreciable influence on the different discharge parameters. Besides, the determination of the escape factors for the Hg resonance lines at 254 nm and 185 nm are not for the least insignificant.