A microscopic theory of density fluctuations in partially ionized gases

This investigation develops a set of exact kinetic equations describing density fluctuations in many body systems with S species. These equations are then applied to the analysis of a partially ionized gas with three species: electrons, ions and neutral atoms. The relationship of this theory to earlier kinetic theory investigations is discussed. A particularly simple approximation for the non-local, non-Markovian collision kernels in these kinetic equations is introduced and used to compute the dynamic structure factors S(k, omega ) characterizing the scattering of electromagnetic radiation (both Thomson and Rayleigh) from partially ionized gases.