Structure and Dynamics of the Inner Boundary of the Plasma Sheet: THEMIS Observations

During its coast phase from mid of March until end of April 2007, the THEMIS spacecraft monitor the pre-midnight region of the near-Earth plasma sheet, crossing its inner edge near the geomagnetic equator. The pearls-on- string configuration of the THEMIS constellation enables to study motion of the inner boundary of the plasma sheet and plasma sheet particle injections into the inner magnetosphere during variations of geomagnetic activity. In this paper, we present profiles of particle energy fluxes along the spacecraft trajectory (nearly radial) obtained by the ESA and SST instruments during substorms. Using the small separations (0.3 - 0.5 RE) of the three middle probes and the spin-resolution (3 s) of the particle flux data, we study the motion of the particle injection fronts associated with magnetic field variations with time scales from several to several tens of minutes.