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Title: Electrostatic and whistler instabilities excited by an electron beam

ORCiD logo [1];  [1]; ORCiD logo [2];  [2];  [1]
  1. Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California 90095, USA
  2. Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
Publication Date:
Sponsoring Org.:
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Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 7; Related Information: CHORUS Timestamp: 2018-02-15 00:21:32; Journal ID: ISSN 1070-664X
American Institute of Physics
Country of Publication:
United States

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. 2017. "Electrostatic and whistler instabilities excited by an electron beam". United States. doi:10.1063/1.4986511.
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 = {},
doi = {10.1063/1.4986511},
journal = {Physics of Plasmas},
number = 7,
volume = 24,
place = {United States},
year = 2017,
month = 7

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on July 17, 2018
Publisher's Accepted Manuscript

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Cited by: 2works
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  • One-dimensional particle simulations have been carried out to study the low-frequency broadband electrostatic noise that propagates almost perpendicularly from the magnetic field line when a nonrelativistic electron beam is injected into space from a spacecraft. For T{sub e} = T{sub i} the electrostatic ion cyclotron waves appear as well as the waves near the lower hybrid frequency. When the magnetic field is reduced so that {Omega}{sub e} << {omega}{sub pe} in a nonisothermal plasma. T{sub e} > T{sub i}, oblique ion acoustic instabilities appear to propagate almost perpendicular to the magnetic field. In addition, a very low frequency mode atmore » {omega} << {Omega}{sub i} is found to be generated by the electrons flowing into the conductor. Both the injected beam electrons as well as the ambient electrons flowing into the spacecraft are responsible for generating those instabilities, which accelerate ions perpendicular to the magnetic field.« less
  • An electron temperature anisotropy T{sub {perpendicular}e}/T{sub {parallel}e}{gt}1 leads to excitation of three distinct instabilities in collisionless plasmas at frequencies below the electron cyclotron frequency {vert_bar}{Omega}{sub e}{vert_bar} (Here {perpendicular} and {parallel} denote directions relative to the background magnetic field {bold B}{sub o}.). Linear Vlasov theory is used to study these growing modes, with emphasis on the scaling of the temperature anisotropy at instability threshold. If the electron plasma frequency {omega}{sub e} is greater than {vert_bar}{Omega}{sub e}{vert_bar} and electrons are sufficiently hot, the whistler is the unstable mode with smallest anisotropy threshold; this electromagnetic mode has maximum growth rate at propagation parallelmore » to {bold B}{sub o}. At {omega}{sub e}{gt}0.5{vert_bar}{Omega}{sub e}{vert_bar}, an electrostatic electron anisotropy instability can arise propagation oblique to {bold B}{sub o}; this mode may have the smallest threshold for sufficiently cool electrons and {omega}{sub e}{approximately}{vert_bar}{Omega}{sub e}{vert_bar}. And T{sub {perpendicular}e}/T{sub {parallel}e}{gt}1 drives the {ital z} mode unstable at {omega}{sub e}{lt}{vert_bar}{Omega}{sub e}{vert_bar}; this electromagnetic mode also has maximum growth rate at parallel propagation and is the persistent instability at {omega}{sub e}{approx_lt}0.5{vert_bar}{Omega}{sub e}{vert_bar}. The results are discussed in connection with observations from the polar and auroral regions of the terrestrial magnetosphere. {copyright} 1999 American Geophysical Union« less
  • We carried out a series of 2D simulations to study the beam instability and cyclotron maser instability (CMI) with the initial condition that a population of tenuous energetic electrons with a ring-beam distribution is present in a magnetized background plasma. In this paper, weakly relativistic cases are discussed with the ring-beam kinetic energy ranging from 25 to 100 keV. The beam component leads to the two-stream or beam instability at an earlier stage, and the beam mode is coupled with Langmuir or whistler mode, leading to excitation of beam-Langmuir or beam-whistler waves. When the beam velocity is large with amore » strong beam instability, the initial ring-beam distribution is diffused in the parallel direction rapidly. The diffused distribution may still support CMI to amplify the X1 mode (the fundamental X mode). On the contrary, when the beam velocity is small and the beam instability is weak, CMI can amplify the Z1 (the fundamental Z mode) effectively while the O1 (the fundamental O mode) and X2 (the second harmonic X mode) modes are very weak and the X1 mode is not excited. In this report, different cases with various parameters are presented and discussed for a comprehensive understanding of ring-beam instabilities.« less
  • The authors study the interactions between an electron beam and whistler, electrostatic, and quasi-upper hybrid waves in a model cold magnetosphere. Their analyses are done both in a linear and nonlinear manner, and look at the growth rate of instabilities as a function of the angle between the wave and electron beam. The growth rates and dominance of different instabilities is a strong function of the angle between the wave and beam.
  • During the Spacelab 2 mission, while an electron beam was being ejected from the shuttle, the Plasma Diagnostics Package (PDP) detected a clear funnel-shaped emission that is believed to be caused by whistler-mode emission from the electron beam. In order to understand the mechanism of this emission, simulations with a three-dimensional partially magnetostatic code have been performed. The simulation results show that whistler-mode and lower hybrid waves are excited by the electron beam, which is initially localized in the column in the three-dimensional simulation system, and that they propagate away from the beam. The wave spectra of the electric andmore » magnetic fields diagnosed at some points show several peaks due to the waves excited by the electron beam. The frequency range of these spectra extends from {omega}{sub pi} to beyond {omega}{sub pe}, which is in qualitative agreement with the PDP data. The intense narrowband electrostatic emission near the electron plasma frequency is observed by the simulations. The simulation results show that the beam instability is responsible for the generation mechanism of these emissions.« less