Contribution to the study of properties of two-temperature plasmas - Application to Argon and Air

In the field of thermal plasmas, numerous industrial processes are characterized by assuming thermal equilibrium. However, these equilibrium conditions are not fulfilled near the boundary of plasmas created by electric arcs or plasma jets. The deviations from the equilibrium change then considerably the kinetics of the chemical environment and can affect the process being studied. Understanding, analysis and prediction of these processes require a modeling of two temperature plasma physics (2T). This model is based on the prior calculation of 2T plasma properties calculation which is the subject of this thesis. The first part of this work is devoted to calculate the two temperatures plasma composition of argon plasma and air plasma. The challenge is to determine the electronic temperature, vibrational and rotational excitation, which are then used to choose the physical laws governing the population of species. While the electron temperature Te can be sufficient to characterize the high temperature plasma, the temperature Tg of the 'heavy' for the low temperatures is needed. There are several theories in the literature to calculate the densities of species for non-equilibrium plasma but the originality of this work is in the establishment of a 'pseudo-kinetic' law governing the settlement of species for the intermediate temperatures. The different methods studied are validated in the case of argon plasma at equilibrium before being applied to a non-equilibrium argon plasma and air plasma. Several results are proposed in order to identify and analyze the differences obtained by the methods applied. The second part concerns the calculation of thermodynamic properties. It is based on a literature review of existing methodologies and data necessary to obtain such properties (enthalpy of formation, energies, and vibrational levels and rotational...). A special effort is made to separate the contributions of those electrons and heavy particles in exchanges of energy. The results (ρ mass density, enthalpy H and heat capacity at constant pressure Cp) are validated by comparison with plasma equilibrium and compared them according to the methods used to calculate composition. The last part of this thesis is dedicated to the calculation of transport coefficients: electrical conductivity σ, thermal conductivity κ and viscosity η for argon plasma at two temperatures. We discuss the outline of calculations intermediate properties (enthalpy of formation, collision cross section, collision integrals) before introducing the different theories available in literature. A calculation at equilibrium is presented to validate the consistency of the expressions chosen before concluding with a presentation of the transport coefficients of thermal non-equilibrium argon plasma. (author)