Diffusive transport of several hundred keV electrons in the Earth's slot region

TitleDiffusive transport of several hundred keV electrons in the Earth's slot region
Publication TypeJournal Article
Year of Publication2017
AuthorsMa, Q, Li, W, Thorne, RM, Bortnik, J, Reeves, GD, Spence, HE, Turner, DL, Blake, JB, Fennell, JF, Claudepierre, SG, Kletzing, CA, Kurth, WS, Hospodarsky, GB, Baker, DN
JournalJournal of Geophysical Research: Space Physics
Date Published09/2017
KeywordsElectron transport; Energetic electron diffusion; pitch angle scattering; Slot region dynamics; Van Allen Probes; Van Allen Probes observation; Waves in plasmasphere
AbstractWe investigate the gradual diffusion of energetic electrons from the inner edge of the outer radiation belt into the slot region. The Van Allen Probes observed slow inward diffusion and decay of ~200-600 keV electrons following the intense geomagnetic storm that occurred on 17 March 2013. During the 10-day non-disturbed period following the storm, the peak of electron fluxes gradually moved from L~2.7 to L~2.4, and the flux levels decreased by a factor of ~2-4 depending on the electron energy. We simulated the radial intrusion and decay of electrons using a 3-dimentional diffusion code, which reproduced the energy-dependent transport of electrons from ~100 keV to 1 MeV in the slot region. At energies of 100-200 keV, the electrons experience fast transport across the slot region due to the dominance of radial diffusion; at energies of 200-600 keV, the electrons gradually diffuse and decay in the slot region due to the comparable rate of radial diffusion and pitch angle scattering by plasmaspheric hiss; at energies of E > 700 keV, the electrons stopped diffusing near the inner edge of outer radiation belt due to the dominant pitch angle scattering loss. In addition to plasmaspheric hiss, magnetosonic waves and VLF transmitters can cause the loss of high pitch angle electrons, relaxing the sharp ‘top-hat' shaped pitch angle distributions created by plasmaspheric hiss. Our simulation indicates the importance of balance between radial diffusion and loss through pitch angle scattering in forming the diffusive intrusion of energetic electrons across the slot region.
Short TitleJ. Geophys. Res. Space Physics

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