Cyclotron Acceleration of Relativistic Electrons Through Landau Resonance With Obliquely Propagating Whistler‐Mode Chorus Emissions
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Omura_et_al_2018JA026374.pdf
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Author(s)
Omura, Yoshiharu
Hsieh, Yi‐Kai
Foster, John C
Erickson, Philip J.
Kletzing, Craig A.
Baker, Daniel N.
Date Issued
April 2019
Journal
JGR Space Physics
Publisher
American Geophysical Union (AGU)
Citation
Omura, Yoshiharu et al. "Cyclotron Acceleration of Relativistic Electrons Through Landau Resonance With Obliquely Propagating Whistler‐Mode Chorus Emissions." JGR Space Physics 124, 4 (April 2019): 2795-2810. © 2019 American Geophysical Union
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Final published version
Abstract
Efficient acceleration of relativistic electrons at Landau resonance with obliquely propagating whistler-mode chorus emissions is confirmed by theory, simulation, and observation. The acceleration is due to the perpendicular component of the wave electric field. We first review theoretical analysis of nonlinear motion of resonant electrons interacting with obliquely propagating whistler-mode chorus. We have derived formulae of inhomogeneity factors for Landau and cyclotron resonances to analyze nonlinear wave trapping of energetic electrons by an obliquely propagating chorus element. We performed test particle simulations to confirm that nonlinear wave trapping by both Landau and cyclotron resonances can take place for a wide range of energies. For an element of large amplitude chorus waves observed by the Van Allen Probes, we have performed detailed analyses of the wave form data based on theoretical framework of nonlinear trapping of resonant electrons. We compare the efficiencies of accelerations by cyclotron and Landau resonances. We find significant acceleration can take place both in Landau and cyclotron resonances. What controls the dynamics of relativistic electrons in the Landau resonance is the perpendicular field components rather than the parallel electric field of the oblique chorus wave. In evaluating the efficiency of nonlinear trapping, we have taken into account variation of the wave trapping potential structure controlled by the inhomogeneity factors.
MIT Department
Haystack Observatory
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DOI of Published Version
https://doi.org/10.1029/2018ja026374
