Dissociation reactive thermal conductivity in a two-temperature plasma

Abstract

Dissociation reactive thermal conductivity (DRTC) is the transfer of dissociation energy in plasma with temperature and, therefore, composition gradient. In the existing theories, calculation of the DRTC coefficient consists of the calculation of diffusion coefficients and plasma composition. The heat flux is then calculated by assigning to every molecule the dissociation energy and by the multiplication of the molecule flux density by this energy.This approach, correct for the LTE plasma, is not adequate for the non-equilibrium two-temperature plasma: it does not allow one to separate the total DRTC coefficient into two components responsible for the heat transfer by electrons and heavy particles (atoms, molecules, ions). Only at LTE, during atom reassociation, do the electrons recuperate the energy they spent during the molecule dissociation. Therefore, in order to separate these two components of DRTC, the kinetics of the dissociation–reassociation processes should be considered. This is done in this paper for nitrogen plasma at atmospheric pressure. Fe, the electron fraction of the total DRTC coefficient, was calculated for Te (electron temperature) in the range 0.4–1.0 eV and Th (heavy particles temperature) from 0.2 eV to Te. It is shown that Fe depends mostly on the electron temperature and increases with increasing electron temperature.