Electrical and Thermal Properties of Plasmas

General theoretical expressions in terms of commonly used transport coefficients are derived and analyzed for the current density and heat flux within a partially ionized gas. Features of the development include the following: an examination of some of the relations between space charge and the Navier‐Stokes hydrodynamic equations of change ending with the conclusion that only a quasi‐neutral gas is consistent with linear flux theory; an explanation in terms of irreversible thermodynamics of the factor of three separating Ahtye and Spitzer‐Härm thermal conductivities; a subsequent demonstration of the numerical equivalence between certain transport calculations based on the Boltzmann and Fokker‐Planck kinetic equations; and a discussion and evaluation of the methods of Yos and Thomas. In addition, it is shown that, apart from a thermal diffusion term, expected to be small, the field‐reduced thermal conductivity is that of Muckenfuss and Curtiss with a Butler‐Brokaw reaction contribution tacked on. This means that the latter form, provided Boltzmann's equation is still reliable, is just as good for ionizing gases as for any other reacting mixture.