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Title: Unraveling the excitation mechanisms of highly oblique lower-band chorus waves

Journal Article · · Geophysical Research Letters
 [1];  [2];  [3];  [4];  [4];  [5];  [5];  [5]; ORCiD logo [6]; ORCiD logo [7];  [8]
  1. Boston Univ., MA (United States). Center for Space Physics; Univ. of California, Los Angeles, CA (United States). Dept. of Atmospheric and Oceanic Sciences
  2. Alternative Energies and Atomic Energy Commission (CEA), Arpajon (France)
  3. Univ. of California, Los Angeles, CA (United States). Dept. of Earth, Planetary, and Space Sciences
  4. Univ. of California, Los Angeles, CA (United States). Dept. of Atmospheric and Oceanic Sciences
  5. Univ. of Iowa, Iowa City, IA (United States). Dept. of Physics and Astronomy
  6. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); New Mexico Consortium, Los Alamos, NM (United States). Space Sciences Division
  7. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  8. Univ. of New Hampshire, Durham, NH (United States). Inst. for the Study of Earth, Oceans, and Space
+ Show Author Affiliations

Excitation mechanisms of highly oblique, quasi-electrostatic lower band chorus waves are investigated using Van Allen Probes observations near the equator of the Earth's magnetosphere. Linear growth rates are evaluated based on in situ, measured electron velocity distributions and plasma conditions and compared with simultaneously observed wave frequency spectra and wave normal angles. Accordingly, two distinct excitation mechanisms of highly oblique lower band chorus have been clearly identified for the first time. The first mechanism relies on cyclotron resonance with electrons possessing both a realistic temperature anisotropy at keV energies and a plateau at 100–500 eV in the parallel velocity distribution. The second mechanism corresponds to Landau resonance with a 100–500 eV beam. In both cases, a small low-energy beam-like component is necessary for suppressing an otherwise dominating Landau damping. In conclusion, our new findings suggest that small variations in the electron distribution could have important impacts on energetic electron dynamics.

Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
National Aeronautics and Space Administration (NASA); USDOE
Grant/Contract Number:
AC52-06NA25396; 967399; 921647; NNX15AF61G; NNX14AI18G; NNX13AI61G; FA9550-15-1-0158; PLR1341359; AGS1405054
OSTI ID:
1345934
Report Number(s):
LA-UR-16-26165
Journal Information:
Geophysical Research Letters, Vol. 43, Issue 17; ISSN 0094-8276
Publisher:
American Geophysical UnionCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 69 works
Citation information provided by
Web of Science

References (41)

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Cited By (17)

Generation of Lower L Shell Dayside Chorus by Energetic Electrons From the Plasma Sheet journal October 2018
An Event on Simultaneous Amplification of Exohiss and Chorus Waves Associated With Electron Density Enhancements journal November 2018
Excitation of Highly Oblique Lower Band and Upper Band Chorus by a Loss Cone Feature and Temperature Anisotropy Distribution journal February 2019
Highly Oblique Lower-Band Chorus Statistics: Dependencies of Wave Power on Refractive Index and Geomagnetic Activity: OBLIQUE CHORUS POWER CHARACTERISTICS journal June 2018
Properties of Intense Field-Aligned Lower-Band Chorus Waves: Implications for Nonlinear Wave-Particle Interactions: INTENSE FIELD-ALIGNED CHORUS WAVE-PACKETS journal July 2018
Whistler Waves Driven by Field‐Aligned Streaming Electrons in the Near‐Earth Magnetotail Reconnection journal May 2019
Energy Transport by Whistler Waves Around Dipolarizing Flux Bundles journal November 2019
Unraveling the Correlation Between Chorus Wave and Electron Beam‐Like Distribution in the Earth's Magnetosphere journal November 2019
Parallel Acceleration of Suprathermal Electrons Caused by Whistler‐Mode Hiss Waves journal November 2019
The Effects of Thermal Electrons on Whistler Mode Waves Excited by Anisotropic Hot Electrons: Linear Theory and 2‐D PIC Simulations journal July 2019
Origin of two-band chorus in the radiation belt of Earth journal October 2019
Polarization of obliquely propagating whistler mode waves based on linear dispersion theory journal December 2016
Linear unstable whistler eigenmodes excited by a finite electron beam journal August 2019
Ion and Electron Dynamics in the Presence of Mirror, Electromagnetic Ion Cyclotron, and Whistler Waves journal October 2019
An excitation mechanism for discrete chorus elements in the magnetosphere journal January 2018
An excitation mechanism for discrete chorus elements in the magnetosphere journal May 2018
Linear unstable whistler eigenmodes excited by a finite electron beam text January 2019

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Related Subjects

58 GEOSCIENCES
oblique chorus excitation
Beam instability
Temperature anisotropy
Lower band chorus
Heliospheric and Magnetospheric Physics