M.: Statistical study of transient plasma structures in magnetotail lobes and plasma sheet boundary layer

Abstract. The present paper is devoted to the statistical study of plasma structures observed at the interface between mag-netospheric lobes and the plasma sheet at distances of 15– 25RE. The majority of the registered structures are bursty earthward ion streams with energies about 10–30 keV known as “beamlets”. The paper describes the results of beam-let statistical analysis for different interplanetary magnetic fields (IMF), clock-angles and various magnetospheric con-ditions. It is shown that the energy of beamlets increases monotonously with a distance from the neutral sheet (NS) during slightly southward IMF and quiet magnetospheric conditions. Under these conditions, beamlets are observed up to 5–6RE over the NS. In contrast, the beamlet energy decreases with increasing distance from the NS if the IMF is northward, and the region of beamlet observation become