Ion jetting at the plasma sheet boundary: Simultaneous observations of incident and reflected particles

Data which show energetic ions jetting towards the earth at the plasma sheet boundary are presented. The ions are spatially dispersed such that the most energetic particles lie furthest from the neutral sheet. Simultaneously, non‐thermal ion spectra were seen in the small particle fluxes moving from the earth. These particles are believed to be the earthward jetting ions after their reflection near the earth. We argue that these dispersion effects result from a combination of a tailward moving source and a cross‐tail electric field.