Cyclotron Acceleration of Relativistic Electrons Through Landau Resonance With Obliquely Propagating Whistler‐Mode Chorus Emissions. Issue 4 (24th April 2019)

• Record Type: Journal Article
• Authors: Omura, Yoshiharu; Hsieh, Yi‐Kai; Foster, John C.; Erickson, Philip J.; Kletzing, Craig A.; Baker, Daniel N.
• Is Part Of: Journal of geophysical research. Volume 124:Issue 4(2019)
• Page Start: 2795
• Page End: 2810
• Publication Date: 2019-04-24
• Subjects: wave particle interaction -- nonlinear process -- whistler‐mode chorus -- radiation belts -- inner magnetosphere -- relativistic electrons; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2018JA026374
• Languages: English
• ISSNs: 2169-9380

Abstract

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. Key Points: Oblique chorus waves can accelerate relativistic electrons effectively through Landau resonance The acceleration is due to the perpendicular component of the wave electric field Nonlinear trapping conditions and efficiency of electron acceleration are confirmed by spacecraft observation