This paper deals with a two-temperature, two-dimensional modelling of a mercury high-pressure plasma stabilized by walls. We consider here a plasma composed of neutral particles, singly ionized positive ions and electrons. Both electron and heavy particle energies are supposed to follow Maxwell distribution functions at different temperatures. Moreover, the electrons were supposed to be carried by the heavy particles in their laminar convection movement. Hydrodynamic conservation equations are then solved by using a 2D semi-implicit finite element scheme. After validation the model is used to discuss deviations from thermal equilibrium due to external arc parameters such as arc current and pressure. These deviations are expressed as differences between electron and heavy particle temperatures. Our results confirm quantitatively for the first time the existence of thermal equilibrium deviations in such types of discharge. These deviations could be significant in many cases, especially when current or pressure is relatively low. Furthermore, we show that, in such types of discharge, the hot core is always closer to thermal equilibrium than the outer discharge jacket.

The variation of the principal characteristics of the mercury visible triplet self-reversed lines is studied as a function of radial and temporal profiles of the temperature and of the species densities in high pressure mercury discharges (∼2 and ∼3 atm) operating on 50 Hz ac. An investigation is made into the effect of different theoretical and experimental parameters on the shape of calculated self-reversed lines. By comparison between experimental and theoretical results an estimation is made of the broadening constants and of the transition probabilities of the lines.

In this work the broadening of the red wing of the 253.7 nm resonance mercury line is used to determine the radial distribution of the neutral atom density in a high-pressure mercury discharge. Abel inversion allows resolution of the integral relation between the wavelength at the maximum intensity of the red-wing resonance line and the square of the neutral atom density. This method, which does not require the assumption of local thermodynamic equilibrium, is applied to the pressure range 0.2 - 5 bar. Results are compared with those obtained from the broadening of the 491.6 nm mercury line.

The broadening and shift of the optically thin Hg 577 and 491.6 nm lines emitted in high-pressure mercury discharges operating at 50 Hz ac frequency are studied. An investigation is carried out in order to appreciate the influence of different factors on the broadening and shift of the local line profile. Comparison between computed and experimental apparent line shapes permits the determination of a set of broadening and shift parameters which leads to a satisfactory representation of the line shapes. Furthermore, applications to mercury discharge diagnosis are proposed.