Nonlinear interactions between radiation belt electrons and chorus waves: dependence on wave amplitude modulation
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Citation (published version)Longzhi Gan, Wen Li, Qianli Ma, Jay Albert, Anton Artemyev, Jacob Bortnik. 2020. "Nonlinear Interactions Between Radiation Belt Electrons and Chorus Waves: Dependence on Wave Amplitude Modulation." Geophysical Research Letters, Volume 47, https://doi.org/10.1029/2019GL085987
We use test particle simulations to model the interaction between radiation belt electrons and whistler mode chorus waves by focusing on wave amplitude modulations. We quantify the pitch angle and energy changes due to phase trapping and phase bunching (including both advection and scattering) for electrons with various initial energies and pitch angles. Three nonlinear regimes are identified in a broad range of pitch angle-energy space systematically, each indicating different nonlinear effects. Our simulation results show that wave amplitude modulations can extend the nonlinear regimes, while significantly reducing electron acceleration by phase trapping. By including amplitude modulations, the “advective” changes in pitch angle and energy caused by phase bunching are reduced, while the “diffusive” scattering due to phase bunching is enhanced. Our study demonstrates the importance of wave amplitude modulations in nonlinear effects and suggests that they need to be properly incorporated into future theoretical and numerical studies.
Rights©2020. American Geophysical Union. All Rights Reserved. This is the author manuscript accepted for publication and has undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1029/2019GL085987