Statistical Study of Pitch Angle Diffusion during Substorm Injections

<p>Energetic Electron Precipitation (EEP) associated with substorm injections typically occurs when magnetospheric waves, particularly whistler-mode waves, resonantly interact with electrons to affect their equatorial pitch angle. This can be considered as a diffusion process that scatters particles into the loss cone. In this study, we investigate whistler-mode wave generation in conjunction with electron injections using in-situ wave measurements by the Themis mission. We calculate the pitch angle diffusion coefficient exerted by the observed wave activity using the quasi-linear diffusion approximation and estimate scattering efficiency in the substorm injection region to constrain where and how much scattering happens typically during these events.</p>

Global observations of substorm injection region evolution: 27 August 2001

We present riometer and in situ observations of a substorm electron injection on 27 August 2001. The event is seen at more than 20 separate locations (including ground stations and 6 satellites: Cluster, Polar, Chandra, and 3 Los Alamos National Laboratory (LANL) spacecraft). The injection is observed to be dispersionless at 12 of these locations. Combining these observations with information from the GOES-8 geosynchronous satellite we argue that the injection initiated near geosynchronous orbit and expanded poleward (tailward) and equatorward (earthward) afterward. Further, the injection began several minutes after the reconnection identified in the Cluster data, thus providing concrete evidence that, in at least some events, near-Earth reconnection has little if any ionospheric signature.

Bootstrap energization of relativistic electrons in magnetized plasmas

In situ and remote observations indicate that relativistic or ultra relativistic electrons are formed at various magnetized configurations. It is suggested that a specific bootstrap mechanism operates in some of these environments. The mechanism applies to (a) relativistic electrons observed on localized field lines in outer radiation belt - through a process initiated at a distant substorm injection; (b) relativistic electrons observed at the interplanetary medium - through a process initiated via coronal injection, at large distances from flares or propagating CME; (c) ultra-relativistic electrons deduced at the galactic jets - through a process initiated via local injection at the small-scale magnetic field. The injected nonisotropic electrons excite whistler waves which boost efficiently the tail of the electron distribution.

Pc5 waves generated by substorm injection: a case study

We analyzed the spectral-polarized characteristics of Pc5 ULF waves observed on 17 September 2000 after the 03:20:25 UT substorm onset with the satellites GOES 8 and 10 located east and west of the onset location. In the course of the event, the wave polarization changed from mixed (between toroidal and poloidal) to poloidal, and then to mixed again. The hodogram of magnetic field oscillations rotated counterclockwise at GOES 8, and clockwise at GOES 10. It is suggested that the satellites detected the waves generated by the substorm injected clouds of the charged particles drifting in the magnetosphere in the opposite azimuthal directions: GOES 8 (located east of the substorm onset) detected the wave generated by an electron cloud, and GOES 10 (west of the onset) detected the wave generated by a positive ion cloud. This interpretation is confirmed by the energetic particles data recorded by LANL satellites.