On the formation of the central plasma sheet by echo clusters of ion beams

Multiple energy dispersion structures of H$^+$ ions that were observed at the passage of the INTERBALL-Auroral satellite through the plasma sheet at a geocentric distance of about $\sim3R_E$, where $R_E$ is the radius of the Earth, on November 3, 1996, have been analyzed. The structure in the plasma sheet boundary layer, which has direct dispersion in energy and invariant latitude, in the range of $0.5$–$10.0$ keV (velocity-dispersed ion structure) is an “autograph” of accelerated ion beams (primary beamlets) generated in the current sheet along the geomagnetic tail. The central plasma sheet contains five dispersion structures c1–c5 with the average energy ranging from $2.80$ to $7.36$ keV. The average energy of the structures increases with a decrease in the latitude. The event under consideration is a case of the regime of formation of the central plasma sheet by echo beamlets of the accelerated ion beam in the absence of a diffusion thermalized population of ions. This phenomenon is possibly explained by the fact that a magnetically quite period was observed three days before the passage of the satellite, when the regime of long-term diffusion of particles from the central plasma sheet occurred.