Thermal plasmas in gas mixtures

The calculation and measurement of the properties of thermal plasmas in mix tures of different gases are reviewed. The calculation of composition, ther modynamic properties and transport coefficients is described. Particular at tention is given to the calculation of diffusion coefficients, which is a s ignificant problem in mixed-gas plasmas. The combined diffusion coefficient formulation is shown to be a useful method for the treatment of diffusion. Computational fluid dynamic modelling of thermal plasmas in gas mixtures i s considered, using the examples of demixing in welding arcs, the turbulent mixing of atmospheric air into a plasma jet and a plasma waste destruction process. Diagnostic techniques for mixed-gas plasmas, in particular emissi on spectroscopy, laser scattering and laser-induced fluorescence, are discu ssed.