Journal article
Parallel Acceleration of Suprathermal Electrons Caused by Whistler‐Mode Hiss Waves
Geophysical research letters, Vol.46(22), pp.12675-12684
11/28/2019
DOI: 10.1029/2019GL085562
Abstract
Suprathermal electrons (~0.1–10 keV) in the inner magnetosphere are usually observed in a 90°‐peaked pitch angle distribution, formed due to the conservation of the first and second adiabatic invariants as they are transported from the plasma sheet. We report a peculiar field‐aligned suprathermal electron (FASE) distribution measured by Van Allen Probes, where parallel fluxes are 1 order of magnitude higher than perpendicular fluxes. Those FASEs are found to be closely correlated with large‐amplitude hiss waves and are observed around the Landau resonant energies. We demonstrate, using quasilinear diffusion simulations, that hiss waves can rapidly accelerate suprathermal electrons through Landau resonance and create the observed FASE population. The proposed mechanism potentially has broad implications for suprathermal electron dynamics as well as whistler mode waves in the Earth's magnetosphere and has been demonstrated in the Jovian magnetosphere.
Plain Language Summary
Hiss waves are structureless and incoherent “hissy” emissions found in the magnetized near‐Earth space, typically in a frequency range from 0.1 to 2 kHz. Hiss waves have traditionally been treated as an energetic electron removal mechanism, because they can precipitate energetic electrons through resonant interactions and cause electron loss into the atmosphere. Here we show, by presenting observations from NASA's Van Allen Probes, that intense hiss waves are accompanied by enhancements of field‐aligned suprathermal electrons. We propose that hiss waves can accelerate suprathermal electrons as they travel at the same speed in the direction along the magnetic field. Computer simulations successfully reproduce the rapid enhancement of field‐aligned suprathermal electrons under the impact of hiss waves, with detailed features similar to observations.
Key Points
Pronounced field‐aligned suprathermal electron enhancements are observed in correlation with intense hiss waves
Numerical simulations reproduce field‐aligned electron distributions similar to observations
Intense hiss waves can accelerate field‐aligned suprathermal electrons via Landau resonance on a timescale of several minutes
Details
- Title: Subtitle
- Parallel Acceleration of Suprathermal Electrons Caused by Whistler‐Mode Hiss Waves
- Creators
- Jinxing Li - University of California, Los AngelesQianli Ma - Boston UniversityJacob Bortnik - University of California, Los AngelesWen Li - Boston UniversityXin An - University of California, Los AngelesGeoffrey D. Reeves - Los Alamos National LaboratoryHerbert O. Funsten - Los Alamos National LaboratoryHarlan Spence - University of New HampshireDaniel N. Baker - Laboratory for Atmospheric and Space PhysicsWilliam S. Kurth - University of IowaGeorge B. Hospodarsky - University of IowaDavid P. Hartley - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Geophysical research letters, Vol.46(22), pp.12675-12684
- DOI
- 10.1029/2019GL085562
- ISSN
- 0094-8276
- eISSN
- 1944-8007
- Number of pages
- 10
- Grant note
- National Science Foundation (NSF) (AGS‐1923126; AGS‐1723588; AGS‐1847818) National Aeronautics and Space Administration (NASA) (80NSSC18K1227; NNX16AG21G; NNX14AN85G; NNX14AI18G; NNX17AG07G; NAS5‐01072) Alfred P. Sloan Research Fellowship (FG‐2018‐10936) DOD | USAF | AFMC | Air Force Office of Scientific Research (AFOSR) (FA9550‐15‐1‐0158) U.S. Department of Energy (DOE) (SC0010578)
- Language
- English
- Date published
- 11/28/2019
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984455277302771
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