Evidence for energetic electron and iondispersive microinjections in theEarth's magnetotail as far as 27 R_E

Abstract. High energy and time resolution measurements of energetic electron and ion fluxes obtained by the DOK-2 experiment on board the Interball-tail satellite provide us the opportunity to study the short-lived (1–3min), localized, and often periodic and dispersive flux increases within the plasma sheet. We have deliberately selected and studied two intervals corresponding to the dawn and dusk magnetotail flanks. Dispersive electron (ion) bursts in the dawn side (dusk side) are observed from L=7 to L=27. These bursts, having an individual entity, are termed microinjections and are observed in radial distances greater than those predicted by the ``injection boundary model." In this paper we suggest that the dispersive fluxes at widely separated radial distances are produced by multiple pulsating isospectrum surfaces ordered in succession. At the inner edge of the plasma sheet, the isospectrum surface is considered by Sarafopoulos (2002) as a meandering injection boundary. Roughly, we estimate that the wavelength for an oscillating isospectrum surface is <∼7R_E. A newly-injected population can coexist with the population from another injection center. These electron-ion drifts probably lead to the formation of the profound dawn-dusk species dependent asymmetry of energetic particles within the plasma sheet.

Key words. Magnetospheric physics (plasma sheet; energetic particles, precipitating; MHD waves and instabilities)