Magnetosphere-Ionosphere Coupling in the Region of Electron Diffuse Aurora: The Role of Multiple Atmospheric Reflections

Abstract:

In the diffuse aurora, precipitating electrons initially injected from the plasmasheet via wave-particle interaction processes degrade in the atmosphere toward lower energies and produce secondary electrons via impact ionization of the neutral atmosphere. These precipitating electrons can be additionally reflected back into the magnetosphere by the conjugate atmospheres, leading to a series of multiple reflections that can greatly influence precipitating flux at the upper ionospheric boundary (700-800 km) and the resultant secondary electron population. We present the solution of the Boltzmann-Landau kinetic equation that uniformly describes the entire electron distribution function in the diffuse aurora, including the affiliated production of secondary electrons (E < 600 eV). This solution takes into account, for the first time, the role of multiple atmospheric reflections of the precipitated electrons that initially were moved into the loss cone via wave-particle interaction processes in the Earth’s plasmasheet.