Ionosphere-Plasmasphere Superthermal Electron Coupling: Two-Stream Code Versus Fokker-Plank Kinetic Model

Superthermal Electrons (SEs) are a major energy contributor to the ionosphere and inner plasmasphere via Coulomb collisional coupling with the thermal plasma distribution along the magnetic field line. That energy input, in turn, provides feedback to the thermal population by controlling the ion and election temperature. In this study, we compare two approaches to modeling Ionosphere-Plasmasphere superthermal electron coupling: The two-stream model and Fokker-Plank Kinetic Model. Originally developed to study photoelectron fluxes at Earth more than forty years by Nagy and Banks (1970), the two-stream transport code has since been routinely used to examine superthermal electron transport in the Earth's and planetary ionospheres. Recent studies by Richards and Peterson (2008) continue this legacy, demonstrating an excellent comparison of calculated backscattered photoelectron fluxes in the night ionosphere with corresponding FAST satellite data. The Fokker-Plank Kinetic developed by Khazanov et al. (1994) has also been used in several studies looking at superthermal electron (SE) transport the resulting energy interplay between the ionosphere and magnetosphere. These studies examine such diverse features as the transport of SEs , the energy deposition rates to the thermal electrons regulated by a complete description of Coulomb collisions, and the role of SEs in accelerating ions during plasmaspheric refilling. The two-stream and Fokker-Plank approaches have different theoretical underpinnings and representations of the physical processes underlying SE transport. By juxtaposing the results we hope to draw out the essential features and processes. We directly compare these two models driven by identical solar irradiances from the Flare Irradiance Spectral Model (FISM; Chamberlin et al., 2007).