Influence of Radiative Absorption on the Establishment of Local Thermodynamic Equilibrium

Abstract

By solving the coupled system of collisional-radiative rate equations for a homogeneous and steady-state plasma as a function of the radiative excitation rates one obtains the population densities of the ground and of the excited levels for any given degree of reabsorption. One finds that in hydrogen plasmas which are completely optically opaque towards all Lyman lines and partially optically opaque towards H_α the equilibrium populations will not be established for electron densities below 1X10¹⁶ cm^-3.