Energized electron signatures within standing kinetic Alfven waves in the inner magnetosphere

Standing Alfven eigenmodes with perpendicular scales on the order of the equatorial ion gyroradius are known as kinetic scale field line resonances (KFLRs) and are observed to peak at substorm onset well into the inner magnetosphere (Chaston et al., 2014). Cluster observations (Hull et al., 2021) have also illustrated that substorm auroral bead formation and currents are associated with these waves. In order to better understand the electron energization that leads to the associated auroral precipitation, we present results of multi-period simulations of KFLRs using a gyrofluid-kinetic electron model (Damiano et al., 2015) in a dipolar magnetic field topology with the inclusion of both hot magnetospheric and cold ionospheric sourced electron populations. We track the electron response at different latitudes and compare the simulation results with satellite observations. We illustrate the formation of highly field aligned electron distributions (primarily manifest in the cold electron population) that are linked to electron trapping effects and are in very good agreement with Cluster observations at mid-latitudes (Hull et al., 2021). At high latitudes, broadband electron distributions with energies reaching keV levels are evident in both upward and downward current regions that are consistent with the characteristics of energized electrons observed by the DMSP satellites. The simulations also illustrate that this electron energization is a significant sink of Alfven wave energy that can damp an undriven standing mode in a few eigenperiods.