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Title: Wave-driven butterfly distribution of Van Allen belt relativistic electrons

Van Allen radiation belts consist of relativistic electrons trapped by Earth's magnetic field. Trapped electrons often drift azimuthally around Earth and display a butterfly pitch angle distribution of a minimum at 90° further out than geostationary orbit. This is usually attributed to drift shell splitting resulting from day–night asymmetry in Earth’s magnetic field. However, direct observation of a butterfly distribution well inside of geostationary orbit and the origin of this phenomenon have not been provided so far. Here we report high-resolution observation that a unusual butterfly pitch angle distribution of relativistic electrons occurred within 5 Earth radii during the 28 June 2013 geomagnetic storm. In conclusion, simulation results show that combined acceleration by chorus and magnetosonic waves can successfully explain the electron flux evolution both in the energy and butterfly pitch angle distribution. Finally, the current provides a great support for the mechanism of wave-driven butterfly distribution of relativistic electrons.
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  1. Changsha Univ. of Science and Technology, Changsha (China). School of Physics and Electronic Sciences
  2. Univ. of Science and Technology of China, Hefei (China). Chinese Academy of Sciences Key Laboratory for Basic Plasma Physics
  3. Chinese Academy of Sciences (CAS), Beijing (China). Center for Space Science and Applied Research
  4. Univ. of Colorado, Boulder, CO (United States). Laboratory for Atmospheric and Space Physics
  5. Univ. of New Hampshire, Durham, NH (United States). Institute for the Study of Earth, Oceans, and Space
  6. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  7. The Aerospace Corporation, Los Angeles, CA (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
2012CB825603; 41531072; 41274165; 41204114
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 6; Journal ID: ISSN 2041-1723
Nature Publishing Group
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE; National Natural Science Foundation of China (NNSFC)
Country of Publication:
United States