The reactive thermal conductivity of thermal equilibrium and nonequilibrium plasmas: Application to nitrogen

The accuracy of numerical simulation on plasma behavior depends strongly on the reliability of thermophysical property data. Large number of studies for thermal plasma properties in the local thermodynamic equilibrium (LTE) exist; however, the database for thermal nonequilibrium plasmas is still far from completeness. This paper derives a general expression of total reactive thermal conductivity (TRTC) with great applicability to monatomic, diatomic, and polyatomic gases in terms of a two-temperature model. The derived formula is applied to nitrogen plasmas under thermal equilibrium and nonequilibrium conditions, considering its wide use in plasma systems and switching devices. Typical calculated results of TRTC with two different Saha equations and Guldberg-Waage equations in the temperature range of 300 K-40000 K under different degrees of nonequilibrium are given and compared with those computed according to Brokaw and Butler's derivation for the special case of LTE plasmas, which shows excellent agreement. The influence of different expressions for Saha equations and Guldberg-Waage equations, together with different pressures of 0.1, 1, 3, 5, and 10 atm, on the TRTC evaluated by this newly developed expression is presented as well. These provide reliable reference data for use in the simulation of plasmas.