Energetic Electron Injection and Precipitation as Seen from RCM Bubble Simulation

Although principal possibility to form the energetic electron (EE) injections by transient fast flow bursts was demonstrated, details and quantitative aspects of injection process need to be further investigated based on advanced models. Here we use self-consistent RCM-I simulation initiated by the short-duration (5-min long) localized (~3 Re width) density depletion (evacuating 90% of flux tube content) at the tailward simulation boundary (~18 Re) to look on resulted dynamics of energetic electrons as they are accelerated, injected and then drift eastward in the magnetosphere and precipitate into the atmosphere. We demonstrate that, starting from ordinary plasma sheet population, 50–200 keV electron flux dramatically increases by betatron-like acceleration when the bubble head enter the inner magnetosphere at r < 8–10 Re, and finally reaches as high flux values as 105 (cm2 s sr keV)−1 forming an injected electron cloud. At this time, a sudden onset of EE precipitation develops in the conjugate ionosphere in a couple of minutes. Although simulation uses some approximations (like isotropic precipitation from drifting cloud) and describes an elementary act of injection, it is capable to reproduce basic known global features of precipitation dynamics and geometry including eastward drift along the auroral zone (with roughly 1 h drift period) and a crescent-shaped precipitation zone with minimal precipitation at dusk.