ABSTRACT
This chapter describes "effective population" method, a statistical model approach that involves breakdown of excited atoms and ions subjected to action of internal plasma microfields and uses exact functions of these microfields to obtain probability distributions for effective statistical weights of bound states or for effective populations of excited states. In this chapter the discussion is limited to radiative properties of a high-density plasma. Three main processes exist that determine the spectral emissivity and absorption coefficient of gaseous media and low-temperature plasma: free-free electron transitions in the electric field of ions or neutral atoms or molecules; free-bound transitions; and bound-bound transitions. A useful method for determining the domain of existence of local thermal equilibrium (LTE) that accounts for the reabsorbed radiation contribution was provided by N. V. Denisova et al. The properties of an equilibrium low-temperature plasma are, in principle, known if the fully partitioned function for all the states of the system of Coulomb-interacting particles within the plasma is known.
