Glow discharge in low pressure plasma PVD: mathematical model and numerical simulations

In this paper we analyze the problem of glow discharge in low pressure plasma in industrial plant, for chambers of different shapes and various working parameters, like pressure and electric potential. The model described is based upon a static approximation of the AC configuration with two electrodes and a drift diffusion approximation for the current density of positive ions and electrons. A detailed discussion of the boundary conditions imposed is given, as well as the full description of the mathematical model. Numerical simulations were performed for a simple 1D model and two different 2D models, corresponding to two different settings of the industrial plant. The simpler case consists of a radially symmetric chamber, with one central electrode (cathode), based upon a DC generator. In this case, the steel chamber acts as the anode. The second model concerns a two dimensional horizontal cut of the most common plant configuration, with two electrodes connected to an AC generator. The case is treated in a "quasi-static" approximation. The three models show some common behaviours, particularly including the main expected features, such as dark spaces, glow regions and a wide "plasma region". Furthermore, the three shown models show some similarities with previously published results concerning 1D and simplified 2D models, as well as with some preliminary results of the full 3D case.Comment: 16 pages, 11 figures, in pres

Thermodynamics of equilibria in the model development the phase and reaction system nh3-co2-h2o and parameter evaluation through optimization methods

Urea is produced industrially through the reaction of ammonia and carbon dioxide. The synthesis, carried out at high pressures of around 140-250 bar and at temperatures ranging from 180 C-200 C₁can best be described as a two stage process, with ammonium carbamate being an intermediate product…Applied SciencesChemical Engineerin