Proceedings of 17th International Symposium on Plasma Chemistry, Toronto, Canada, August 7-12, 2005 Two-Temperature Chemically Non-Equilibrium Modeling of Argon Induction Plasmas with Diatomic Gas Takayuki Watanabe 1 , Nobuhiko Atsuchi 2 , and Masaya Shigeta 1 1 Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, Yokohama, Japan 2 Department of Nuclear Engineering, Tokyo Institute of Technology, Tokyo, Japan Abstract A non-equilibrium modeling of argon-oxygen and argon-hydrogen induction thermal plasmas was performed without thermal and chemical equilibrium assumptions. Reaction rates of dissociation and recombination of diatomic gas and ionization were taken into account. A substantial deviation from LTE exists near the torch wall in argon-oxygen induction plasmas under atmospheric pressure, while small deviation in argon-hydrogen plasmas results from the large collision frequency electrons and hydrogen atoms. 1. Introduction Induction thermal plasma approach has been applied for many fields. Attractive recent applications are treatment of harmful materials and recovery of useful material from wastes [1]. Another important application is production of high-quality and high-performance materials, such as synthesis of nanoparticles, deposition of thin films, and plasma spraying. In these applications, thermal plasmas with adding reactive gas are desirable to enhance the chemical reactivity of the plasmas. Sophisticated modeling considering chemical reaction has been required for industrial applications. However, thermal plasmas have been mainly treated with equilibrium conditions. The purpose of this work is to develop two-temperature chemically non-equilibrium (2T-CNE) modeling of induction plasmas, comprising argon-oxygen and argon-hydrogen mixtures. This formulation including finite-rates of the dissociation and ionization is presented using higher-order approximation of the Chapman-Enskog method [2] for the estimation of the transport properties. 2. Numerical formulation 2-1 Thermodynamic and transport properties Up to now, modeling of induction thermal plasmas has been performed with the first-order approximation of the Chapman-Enskog method because higher-order of Sonine polynomial expansion requires many kinds of collision integrals resulting in the complex formula. The first-order approximation may cause errors especially for electrical conductivity and thermal conductivity of electron translational contribution over 0 5 10 15 20 25 0 5000 10000 15000 Ar 100% Ar 90% Ar 70% Ar 50% Ar 30% Ar 10% H 2 100% Thermal Conductivity [W m -1 K -1 ] Temperature [K] 0 0.5 1 1.5 2 2.5 3 3.5 4 0 5000 10000 15000 Ar 100% Ar 90% Ar 70% Ar 50% Ar 30% Ar 10% O 2 100% Thermal Conductivity [W m -1 K -1 ] Temperature [K] Fig. 2 Thermal conductivity of mixtures of argon and hydrogen. Fig. 1 Thermal conductivity of mixtures of argon and oxygen.