Unraveling the Formation Mechanism for the Bursts of Electron Butterfly Distributions: Test Particle and Quasilinear Simulations

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Abstract
Energetic electron dynamics is highly affected by plasma waves through quasilinear and/or nonlinear interactions in the Earth s inner magnetosphere. In this letter, we provide physical explanations for a previously reported intriguing event from the Van Allen Probes observations, where bursts of electron butterfly distributions at tens of keV exhibit remarkable correlations with chorus waves. Both test particle and quasilinear simulations are used to reveal the formation mechanism for the bursts of electron butterfly distribution. The test particle simulation results indicate that nonlinear phase trapping due to chorus waves is the key process to accelerate electrons to form the electron butterfly distribution within ~30 s, and reproduces the observed features. Quasilinear simulation results show that although the diffusion process alone also contributes to form the electron butterfly distribution, the timescale is slower. Our study demonstrates the importance of nonlinear interaction in rapid electron acceleration at tens of keV by chorus waves.
Notes
Year of Publication
2020
Journal
Geophysical Research Letters
Volume
47
Number
Number of Pages
e2020GL090749
Date Published
10/2020
URL
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL090749
DOI
https://doi.org/10.1029/2020GL090749