Energetic electron injections observed by the MMS at dusk sector dayside magnetosphere associated with field depressions of compressional ULF waves: identifying the source

Abstract:

Understanding the detailed physical mechanisms that transport and energize plasma up to MeV energies in the near Earth-Space is important for safe unmanned and manned space operations. During an event of October 2015, the four MMS spacecraft traversed from the dayside boundary layer to the dusk sector dayside boundary layer at mid-latitudes (Z_GSM ~-5 to -3.6) where it observed periods of compressional ULF waves for 3 hrs, possibly driven by the KHI, with intervals of high-energy electrons in the loss cone during the magnetic field depressions. These electrons could originate from outer radiation belt or from the large diamagnetic cavities MMS observed 7-8 hrs earlier and which were filled with trapped population of high energy electrons. The conjunction with Van Allen probes in the inner magnetosphere, and Cluster in the plasma sheet, and relatively steady IMF > 9 hrs allows us to study the source of these energetic electrons by comparing phase space densities at different particle energies and magnetic moments. GAMERA global MHD simulations and meso-scale 3-D MHD simulations with test particles are used for identifying mechanisms for electron energization, trapping, transport and subsequent release during the event, and to explain the detailed physical mechanism producing the injection signature and subsequent fate of these particles.