Low energy charged particle observations in the 'auroral' magnetosphere - First results from the Akebono (EXOS-D) satellite

The EXOS-D satellite has undertaken studies of particle-acceleration processes in the auroral magnetosphere; its low energy particle instrument gathers data on the energy and pitch-angle distributions of auroral electrons and ions, in conjunction with analyses of mass/charge of positive ions and onboard detections of particle-flux modulations in the HF and VLF. Attention is presently given to unique examples of high particle activity in the polar cap, and hot plasma distributions along the transpolar arc. These data are interpreted as signatures of longitudinal and/or temporal fluctuations of the magnetosheath plasma injection into the polar cusp.