Flux limiting due to electron impact excitation energy loss

Large radiation losses in the electron energy balance equation due to electron impact excitation can cause the parallel scale length to become small enough that a short mean-free path expansion becomes questionable for the high-speed tail electrons. It then becomes necessary to limit the parallel electron heat flux so that it remains below its free-streaming value nT3/2/m, where n, T, and m are the electron density, temperature, and mass. A Boltzmann inelastic scattering col- lision operator is adopted to investigate whether electron impact excitation can lead to a self-consistent flux limit by depleting the electron tail.