Bounce resonance scattering of radiation belt electrons by low-frequency hiss: Comparison with cyclotron and Landau resonances

TitleBounce resonance scattering of radiation belt electrons by low-frequency hiss: Comparison with cyclotron and Landau resonances
Publication TypeJournal Article
Year of Publication2017
AuthorsCao, X, Ni, B, Summers, D, Zou, Z, Fu, S, Zhang, W
JournalGeophysical Research Letters
Date Published09/2017
Keywordsbounce resonance; Low-frequency hiss; Radiation Belt Dynamics; Van Allen Probes; wave-particle interactions
AbstractBounce-resonant interactions with magnetospheric waves have been proposed as important contributing mechanisms for scattering near-equatorially mirroring electrons by violating the second adiabatic invariant associated with the electron bounce motion along a geomagnetic field line. This study demonstrates that low-frequency plasmaspheric hiss with significant wave power below 100 Hz can bounce-resonate efficiently with radiation belt electrons. By performing quantitative calculations of pitch-angle scattering rates, we show that low-frequency hiss induced bounce-resonant scattering of electrons has a strong dependence on equatorial pitch-angle αeq. For electrons with αeq close to 90°, the timescale associated with bounce resonance scattering can be comparable to or even less than 1 hour. Cyclotron- and Landau-resonant interactions between low-frequency hiss and electrons are also investigated for comparisons. It is found that while the bounce and Landau resonances are responsible for the diffusive transport of near-equatorially mirroring electrons to lower αeq, pitch-angle scattering by cyclotron resonance could take over to further diffuse electrons into the atmosphere. Bounce resonance provides a more efficient pitch-angle scattering mechanism of relativistic (≥ 1 MeV) electrons than Landau resonance due to the stronger scattering rates and broader resonance coverage of αeq, thereby demonstrating that bounce resonance scattering by low-frequency hiss can contribute importantly to the evolution of the electron pitch-angle distribution and the loss of radiation belt electrons.
URLhttp://onlinelibrary.wiley.com/doi/10.1002/2017GL075104/full
DOI10.1002/2017GL075104
Short TitleGeophys. Res. Lett.


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