EVALUATION OF TRANSPORT-COEFFICIENTS IN PLASMAS CONTAINING ARGON AND SODIUM

Results of a theoretical evaluation of number densities and transport coefficients for low-temperature (2000 K to 20 000 K) argon plasma con taining up to 10% of added sodium are presented. It is taken that the plasma is kept under a constant pressure, equal to, or 5 to 25 times h igher than the normal atmospheric pressure. The plasma is treated as w eakly non-ideal and having attained the LTE state. Use is made of a pr eviously derived modified Debye radius with the cut-off at the Landau length rather than at the smallest ionic radii, which allowed to treat the plasmas investigated as weakly non-ideal. This new Debye radius s ignificantly alters the evaluated equilibrium plasma composition and t ransport coefficients. For the sake of comparison, the analogous syste m of equations for pure argon was also solved, with the use of the sam e evaluation methodology. The results of the theoretical evaluation of the electrical conductivity for pure argon plasma are compared with t he experimental measurements. The theoretical results are found to be in satisfactory agreement with the available experimental data. On the other hand, the addition of a small amount of sodium is shown to lead to a significant increase in the electron number densities, as well a s in both electrical and thermal conductivities below 10 000 K.