Journal of Geophysical Research
In this preliminary report on low-energy (0.3 to 3 eV) secondary electrons in the auroral E layer (90 to 150 km), we compare intensities of plasma lines observed with the Chatanika radar to theoretical predictions obtained from a detailed numerical model. The model calculations are initiated with a flux of energetic auroral primary electrons which enter the atmosphere and lose energy to electrons, ions, and neutrals through a combination of elastic and inelastic collisions. This flux is chosen in order that the total calculated ionization rate matches one that is deduced from the radar measurements. From these same calculations the steady state secondary electron flux is deduced as a function of altitude, energy, and pitch angle. This flux is used to calculate plasma line intensities which are then compared with observed intensities. Initial comparisons suggest that the plasma line theory, when applied to low altitudes, must include the effect of electron-neutral collisions. When this is done, the good agreement obtained between theory and experiment indicates the promise of this approach for the study of low-energy auroral electrons.
Oran, E. S., V. B. Wickwar, W. Kofman, and A. Newman (1981), Auroral Plasma Lines: A First Comparison of Theory and Experiment, J. Geophys. Res., 86(A1), 199–205, doi:10.1029/JA086iA01p00199.