Two-temperatures modelling of the high pressure Hg discharge lamp: application to determination of the thermodynamic equilibrium state of the plasma

Summary from only given. In the electric discharge plasma the electrons pick up energy from the electric field and partially transfer it to the heavy particles by collisions. Due to the relatively large difference between electron and heavy species mass, the energy exchange between them is rather inefficient. Thus, the electron temperature may be substantially higher than the heavy particle temperature. This paper deals with a two-temperature, 2 D time dependent modelling of a mercury high pressure plasma in a discharge lamp vessel. We consider a plasma composed of neutral particles, singly ionized positive ions and electrons. Both electrons and heavy particles energies are supposed to follow Maxwell distribution function at T/sub e/ and T/sub h/ respectively. We also suppose that the occupation of the internal energy states of the heavy particles is governed by Boltzmann´s law with electron temperature T/sub e/. We neglect the viscous dissipation and we suppose that the electric field is purely axial. We assume that the contribution of magnetic force is negligible. Moreover, the electrons were supposed to be carried by the heavy particles in their convection movement, and that the plasma flow is laminar. It is also assumed that are is axially symmetric, and that electrodes have cylindrical shape. Hydrodynamic conservation equations are then solved by using a 2-D semi-implicit finite element scheme. Furthermore, the determination of a 2-T plasma composition, requires the resolution of the following equation set: the generalized mass action laws, Dalton´s law, and the quasi-neutrality condition of the plasma. After validation the model is used in order to discuss the deviations from thermal equilibrium state due to external are parameters such as are current and pressure. These deviations are expressed as differences between electron and heavy particle temperatures.