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Title: Electrostatic and whistler instabilities excited by an electron beam

Abstract

The electron beam-plasma system is ubiquitous in the space plasma environment. Here in this paper, using a Darwin particle-in-cell method, the excitation of electrostatic and whistler instabilities by a gyrating electron beam is studied in support of recent laboratory experiments. It is assumed that the total plasma frequency (ω pe) is larger than the electron cyclotron frequency (Ω e). The fast-growing electrostatic beam-mode waves saturate in a few plasma oscillations by slowing down and relaxing the electron beam parallel to the background magnetic field. Upon their saturation, the finite amplitude electrostatic beam-mode waves can resonate with the tail of the background thermal electrons and accelerate them to the beam parallel velocity. The slower-growing whistler waves are excited in primarily two resonance modes: (a) through Landau resonance due to the inverted slope of the beam electrons in the parallel velocity and (b) through cyclotron resonance by scattering electrons to both lower pitch angles and smaller energies. It is demonstrated that, for a field-aligned beam, the whistler instability can be suppressed by the electrostatic instability due to a faster energy transfer rate between the beam electrons and electrostatic waves. Such a competition of growth between whistler and electrostatic waves depends on themore » ratio of ω pee. In terms of wave propagation, beam-generated electrostatic waves are confined to the beam region, whereas beam-generated whistler waves transport energy away from the beam.« less

Authors:
ORCiD logo [1];  [1]; ORCiD logo [2];  [2];  [1]
  1. Univ. of California, Los Angeles, CA (United States). Dept. of Atmospheric and Oceanic Sciences
  2. Univ. of California, Los Angeles, CA (United States). Dept. of Physics and Astronomy
Publication Date:
Research Org.:
Univ. of California, Los Angeles, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1474311
Alternate Identifier(s):
OSTI ID: 1371492
Grant/Contract Number:  
SC0010578
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 7; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

An, Xin, Bortnik, Jacob, Van Compernolle, Bart, Decyk, Viktor, and Thorne, Richard. Electrostatic and whistler instabilities excited by an electron beam. United States: N. p., 2017. Web. doi:10.1063/1.4986511.
An, Xin, Bortnik, Jacob, Van Compernolle, Bart, Decyk, Viktor, & Thorne, Richard. Electrostatic and whistler instabilities excited by an electron beam. United States. doi:10.1063/1.4986511.
An, Xin, Bortnik, Jacob, Van Compernolle, Bart, Decyk, Viktor, and Thorne, Richard. Mon . "Electrostatic and whistler instabilities excited by an electron beam". United States. doi:10.1063/1.4986511. https://www.osti.gov/servlets/purl/1474311.
@article{osti_1474311,
title = {Electrostatic and whistler instabilities excited by an electron beam},
author = {An, Xin and Bortnik, Jacob and Van Compernolle, Bart and Decyk, Viktor and Thorne, Richard},
abstractNote = {The electron beam-plasma system is ubiquitous in the space plasma environment. Here in this paper, using a Darwin particle-in-cell method, the excitation of electrostatic and whistler instabilities by a gyrating electron beam is studied in support of recent laboratory experiments. It is assumed that the total plasma frequency (ωpe) is larger than the electron cyclotron frequency (Ωe). The fast-growing electrostatic beam-mode waves saturate in a few plasma oscillations by slowing down and relaxing the electron beam parallel to the background magnetic field. Upon their saturation, the finite amplitude electrostatic beam-mode waves can resonate with the tail of the background thermal electrons and accelerate them to the beam parallel velocity. The slower-growing whistler waves are excited in primarily two resonance modes: (a) through Landau resonance due to the inverted slope of the beam electrons in the parallel velocity and (b) through cyclotron resonance by scattering electrons to both lower pitch angles and smaller energies. It is demonstrated that, for a field-aligned beam, the whistler instability can be suppressed by the electrostatic instability due to a faster energy transfer rate between the beam electrons and electrostatic waves. Such a competition of growth between whistler and electrostatic waves depends on the ratio of ωpe/Ωe. In terms of wave propagation, beam-generated electrostatic waves are confined to the beam region, whereas beam-generated whistler waves transport energy away from the beam.},
doi = {10.1063/1.4986511},
journal = {Physics of Plasmas},
number = 7,
volume = 24,
place = {United States},
year = {Mon Jul 17 00:00:00 EDT 2017},
month = {Mon Jul 17 00:00:00 EDT 2017}
}

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