Journal article
Charged particle behavior in the growth and damping stages of ultralow frequency waves: Theory and Van Allen Probes observations
Journal of geophysical research. Space physics, Vol.121(4), pp.3254-3263
04/2016
DOI: 10.1002/2016JA022447
Abstract
Ultralow frequency (ULF) electromagnetic waves in Earth's magnetosphere can accelerate charged particles via a process called drift resonance. In the conventional drift resonance theory, a default assumption is that the wave growth rate is time independent, positive, and extremely small. However, this is not the case for ULF waves in the real magnetosphere. The ULF waves must have experienced an earlier growth stage when their energy was taken from external and/or internal sources, and as time proceeds the waves have to be damped with a negative growth rate. Therefore, a more generalized theory on particle behavior during different stages of ULF wave evolution is required. In this paper, we introduce a time‐dependent imaginary wave frequency to accommodate the growth and damping of the waves in the drift resonance theory, so that the wave‐particle interactions during the entire wave lifespan can be studied. We then predict from the generalized theory particle signatures during different stages of the wave evolution, which are consistent with observations from Van Allen Probes. The more generalized theory, therefore, provides new insights into ULF wave evolution and wave‐particle interactions in the magnetosphere.
Key Points
The effects of wave growth and damping are considered to generalize the conventional ULF wave‐particle drift resonance theory
Particle signatures are predicted to be very different from the characteristic 180 degree phase shift of particle fluxes across energies
Newly predicted particle signatures are consistent with Van Allen Probe observations, which validate the generalized theory
Details
- Title: Subtitle
- Charged particle behavior in the growth and damping stages of ultralow frequency waves: Theory and Van Allen Probes observations
- Creators
- Xu‐Zhi Zhou - University of California, Los AngelesZi‐Han Wang - Peking UniversityQiu‐Gang Zong - PKU/UCLA Joint Research Institute in Science and EngineeringRobert Rankin - University of AlbertaMargaret G Kivelson - University of California, Los AngelesXing‐Ran Chen - Peking UniversityJ. Bernard Blake - The Aerospace CorporationJohn R Wygant - University of MinnesotaCraig A Kletzing - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.121(4), pp.3254-3263
- DOI
- 10.1002/2016JA022447
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Number of pages
- 10
- Grant note
- NSFC (41421003; 41474140)
- Language
- English
- Date published
- 04/2016
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984199700902771
Metrics
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