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Title: Generation of extremely low frequency chorus in Van Allen radiation belts: ELF CHORUS GENERATION

Recent studies have shown that chorus can efficiently accelerate the outer radiation belt electrons to relativistic energies. Chorus, previously often observed above 0.1 equatorial electron gyrofrequency f ce, was generated by energetic electrons originating from Earth's plasmasheet. Chorus below 0.1 f ce has seldom been reported until the recent data from Van Allen Probes but its origin has not been revealed so far. Because electron resonant energy can approach the relativistic level at extremely low frequency relativistic effects should be considered in the formula for whistler-mode wave growth rate. Here we report high-resolution observations during the 14 October 2014 small storm and firstly demonstrate, using a fully relativistic simulation, that electrons with the high energy tail population and relativistic pitch angle anisotropy can provide free energy sufficient for generating chorus below 0.1 f ce. The simulated wave growth displays a very similar pattern to the observations. Finally, the current results can be applied to Jupiter, Saturn and other magnetized planets.
Authors:
ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [2] ; ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [3] ; ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [4] ; ORCiD logo [5] ; ORCiD logo [6] ; ORCiD logo [7] ; ORCiD logo [8]
  1. School of Physics and Electronic Sciences, Changsha University of Science and Technology, Changsha China
  2. Chinese Academy of Sciences Key Laboratory for Basic Plasma Physics, University of Science and Technology of China, Hefei China
  3. Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen China
  4. Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder Colorado USA
  5. Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham New Hampshire USA
  6. Space Science and Applications Group, Los Alamos National Laboratory, Los Alamos New Mexico USA
  7. ISR Division, Los Alamos National Laboratory, Los Alamos New Mexico USA
  8. Aerospace Corporation, Los Angeles California USA
Publication Date:
Report Number(s):
LA-UR-15-28806
Journal ID: ISSN 2169-9380
Grant/Contract Number:
AC52-06NA25396; NAS5-01072
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Space Physics
Additional Journal Information:
Journal Volume: 122; Journal Issue: 3; Journal ID: ISSN 2169-9380
Publisher:
American Geophysical Union
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE; National Aeronautic and Space Administration (NASA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Heliospheric and Magnetospheric Physics
OSTI Identifier:
1345929