Some new results on electron transport in the atmosphere

Abstract

The penetration, diffusion and slowing down of electrons in a semi-infinite air medium has been studied by the Monte Carlo method. The results are applicable in the atmosphere at altitudes up to ~ 300 km. Most of the results pertain to monoenergetic electron beams, with energies between 2 keV and 2 MeV, injected into the atmosphere at a height of 300 km, either vertically downwards or with a pitch-angle distribution isotropic over the downward hemisphere. Some results were also obtained for various initial pitch angles between 0° and 90°. Information has been generated concerning the following topics: 1. (a) the backscattering of electrons from the atmosphere, expressed in terms of backscattering coefficients, angular distributions and energy spectra; 2. (b) the altitude dependence of energy deposition by electrons and by secondary bremsstrahlung, for incident electron beams that are monoenergetic or have exponential spectra with e-folding energies between 5 and 200 keV; 3. (c) the evolution of electron flux spectra as function of the atmospheric depth, for incident beam energies between 2 and 20 keV.