Subpacket structure in strong VLF chorus rising tones: characteristics and consequences for relativistic electron acceleration
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Foster_et_al-2021-Earth,_Planets_and_Space.pdf
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2.41 MB
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Author(s)
Foster, John C
Erickson, Philip J
Omura, Yoshiharu
Date Issued
July 2021
Journal
Earth, Planets, and Space
Publisher
Springer Science and Business Media LLC
Citation
Foster, John C. et al. "Subpacket structure in strong VLF chorus rising tones: characteristics and consequences for relativistic electron acceleration." Earth, Planets, and Space 73, 1 (July 2021): 140. © 2021 The Author(s)
Version
Final published version
Abstract
Van Allen Probes in situ observations are used to examine detailed subpacket structure observed in strong VLF (very low frequency) rising-tone chorus elements observed at the time of a rapid MeV electron energization in the inner magnetosphere. Analysis of the frequency gap between lower and upper chorus-band waves identifies f[subscript ceEQ], the electron gyrofrequency in the equatorial wave generation region. Initial subpackets in these strong chorus rising-tone elements begin at a frequency near 1/4 f[subscript ceEQ] and exhibit smooth gradual frequency increase across their > 10 ms temporal duration. A second much stronger subpacket is seen at frequencies around the local value of 1/4f[subscript ce] with small wave normal angle (< 10°) and steeply rising df/dt. Smooth frequency and phase variation across and between the initial subpackets support continuous phase trapping of resonant electrons and increased potential for MeV electron acceleration. The total energy gain for individual seed electrons with energies between 100 keV and 3 MeV ranges between 2 and 15%, in their nonlinear interaction with a single chorus element.
MIT Department
Haystack Observatory
Terms of Use
Creative Commons Attribution 4.0 International license
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DOI of Published Version
https://doi.org/10.1186/s40623-021-01467-4
