Very Oblique Whistler Generation By Low Energy Electron Streams

TitleVery Oblique Whistler Generation By Low Energy Electron Streams
Publication TypeJournal Article
Year of Publication2015
AuthorsMourenas, D, Artemyev, AV, Agapitov, OV, Krasnoselskikh, V, Mozer, FS
JournalJournal of Geophysical Research: Space Physics
Date Published04/2015
KeywordsChorus wave; Cyclotron resonance; Landau resonance; oblique whistler; wave generation
AbstractWhistler-mode chorus waves are present throughout the Earth's outer radiation belt as well as at larger distances from our planet. While the generation mechanisms of parallel lower-band chorus waves and oblique upper-band chorus waves have been identified and checked in various instances, the statistically significant presence in recent satellite observations of very oblique lower-band chorus waves near the resonance cone angle remains to be explained. Here we discuss two possible generation mechanisms for such waves. The first one is based on Landau resonance with sporadic very low energy (<4 keV) electron beams either injected from the plasmasheet or produced in situ. The second one relies on cyclotron resonance with low energy electron streams, such that their velocity distribution possesses both a significant temperature anisotropy above 3-4 keV and a plateau or heavy tail in parallel velocities at lower energies encompassing simultaneous Landau resonance with the same waves. The corresponding frequency and wave normal angle distributions of the generated very oblique lower-band chorus waves, as well as their frequency sweep rate, are evaluated analytically and compared with satellite observations, showing a reasonable agreement.
URLhttp://doi.wiley.com/10.1002/2015JA021135
DOI10.1002/2015JA021135
Short TitleJ. Geophys. Res. Space Physics


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