Electrical Conductivity of Partially Ionized Noble Gases

The electrical conductivity of the noble gases—argon, helium, xenon, and krypton—has been calculated for arbitrary degrees of ionization for electron temperatures in the 300-30 000°K range. A variational method elaborated by Robinson and Bernstein was employed in the calculations, along with the electron-atom momentum transfer cross-section values reported by Frost and Phelps. Because of the very low values of the electron-noble-gas atom cross sections near the Ramsauer minimum, Coulomb collisions have been found to influence the conductivity for values of fractional ionization as low as 10−7. For the same reason electron-neutral momentum transfer collisions have been found to be unimportant for values of fractional ionization as low as 10−5, above which the gas behaves as though it were fully ionized. Two limiting degrees of ionization have been defined for each noble gas above or below which the gas can be considered either completely or weakly ionized, respectively. In addition, the influence of electron-electron interactions on the electrical conductivity in the partially ionized regime has been established.