Analytic Expressions for Atmospheric Elastic Collisional Scattering of Energetic Electrons in Magnetic Fields | CU Experts

Abstract; Atmospheric collisions have always been recognized as a major direct loss mechanism for radiation belt electrons inside the loss cone. To quantify the impact of atmospheric collisions, previous studies mostly utilized stochastic Monte Carlo methods or used the diffusion approximation assuming small scattering angles due to collisions. In this study, we introduce a new kinetic approach to quantify how the electron distribution function evolves in response to elastic atmospheric collisions with fully resolved scattering angles. Based on the Boltzmann collision term, we present analytic expressions of the collision term for three different electron populations in Earth's radiation belt: trapped, quasi‐trapped, and precipitating electrons. Our integro‐partial differential equation (PDE) simulation results suggest that atmospheric scattering contributes to the formation of 90‐degree minimum pitch angle distributions in the inner belt. This novel deterministic approach not only provides new physical insights into atmospheric impacts on radiation belts with high computation efficiency but is also compatible with the abundant well‐established Fokker‐Planck models describing collisionless radiation belt physical processes.

VIVO