High and low frequency instabilities driven by a single electron beam in two-electron temperature space plasmas

Mbuli, L. N.; Maharaj, S. K.; Bharuthram, R.

doi:10.1063/1.4851995

Cited by 7 publications

(3 citation statements)

References 29 publications

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“…6 for v dbwo ¼ 1:092 confirm the existence of positive polarity solitons which are shown to be limited by the occurrence of a double layer (M ¼ 0.4049). Considering that the maximum value of the warm electron drift speeds in our study is slightly more than that of the hot electron thermal speed, we conclude based on the results from kinetic theory, 9,10 in particular, Fig. 5 (Ref.…”

Section: Numerical Results and Discussionsupporting

confidence: 56%

“…1(a). The range of warm electron drift speeds (1:084 < v dbw0 1:093), for which positive polarity solitons are supported, lies in the transition region between the slow electron-acoustic and beam-acoustic modes (x=k ¼ v dbw0 ) considering that the beam speed of the warm electrons is only marginally greater than the thermal speed of the hot electrons, 9,10 and therefore, the solitons are associated with the coupled electron-acoustic and beam-acoustic modes. Considering the kinetic theory studies 9,10 which demonstrate that increasing beam speed of the warm electrons invokes a transition from an electronacoustic mode to a beam-acoustic mode, the positive polarity solitons are very likely associated with the slow electronacoustic mode which is coupled with a beam-acoustic mode.…”

Section: Discussionmentioning

confidence: 99%

“…The simulations show that the temperature of the ions plays a much more significant role than the ion flow speed in the formation of the ESWs, which is in agreement with the characteristics of BEN inferred from satellite observations. 2 Whilst kinetic studies [7][8][9][10][11] have shown that the linear electron-acoustic wave accounts for frequencies up to the local electron plasma frequency, solitons which form in the nonlinear stage of the electron-acoustic instability are likely to be responsible for frequencies which exceed the local electron plasma frequency. 12,13 The mentioned studies highlight the importance of the contributions of both linear and nonlinear electron-acoustic waves to high frequency BEN.…”

Section: Introductionmentioning

confidence: 99%

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The effect of a warm electron beam on slow electron-acoustic solitons

2018

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The effects of the inclusion of finite drift speed of a warm electron component on the existence of arbitrary amplitude slow electron-acoustic solitons are investigated in a model with ions and cool, warm, and hot electrons. All plasma species are treated as adiabatic fluids. For fixed densities of the cool, warm, and hot electrons, the admissible Mach number ranges of the supported negative potential solitons are found to widen with increasing warm electron beam speed, up to a maximum value of v dbwo ¼ 0.7. Beyond this maximum value, the soliton Mach number ranges become narrower and vanish completely at v dbwo ¼ 1.084 where a switch to positive polarity solitons occurs. For a fixed value of the drift speed of the warm electrons, the cool electron density value at which the switch to positive polarity soliton occurs is the lowest when there is no streaming of the warm electrons but increases with increasing drift speed.

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Section: Numerical Results and Discussionsupporting

confidence: 56%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The effect of a warm electron beam on slow electron-acoustic solitons

2018

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High and low frequency instabilities driven by counter-streaming electron beams in space plasmas

2014

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A four-component plasma composed of a drifting (parallel to ambient magnetic field) population of warm electrons, drifting (anti-parallel to ambient magnetic field) cool electrons, stationary hot electrons, and thermal ions is studied in an attempt to further our understanding of the excitation mechanisms of broadband electrostatic noise (BEN) in the Earth's magnetospheric regions such as the magnetosheath, plasmasphere, and plasma sheet boundary layer (PSBL). Using kinetic theory, beam-driven electrostatic instabilities such as the ion-acoustic, electron-acoustic instabilities are found to be supported in our multi-component model. The dependence of the instability growth rates and real frequencies on various plasma parameters such as beam speed, number density, temperature, and temperature anisotropy of the counter-streaming (relative to ambient magnetic field) cool electron beam are investigated. It is found that the number density of the anti-field aligned cool electron beam and drift speed play a central role in determining which instability is excited. Using plasma parameters which are closely correlated with the measurements made by the Cluster satellites in the PSBL region, we find that the electron-acoustic and ion-acoustic instabilities could account for the generation of BEN in this region.

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A particle-in-cell approach to obliquely propagating electrostatic waves

2014

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The electron-acoustic and beam-driven modes associated with electron beams have previously been identified and studied numerically. These modes are associated with Broadband Electrostatic Noise found in the Earth's auroral and polar cusp regions. Using a 1-D spatial Particle-in-Cell simulation, the electron-acoustic instability is studied for a magnetized plasma, which includes cool ions, cool electrons and a hot, drifting electron beam. Both the weakly and strongly magnetized regimes with varying wave propagation angle, θ, with respect to the magnetic field are studied. The amplitude and frequency of the electron-acoustic mode are found to decrease with increasing θ. The amplitude of the electron-acoustic mode is found to significantly grow at intermediate wavenumber ranges. It reaches a saturation level at the point, where a plateau forms in the hot electron velocity distribution after which the amplitude of the electron-acoustic mode decays.

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High and low frequency instabilities driven by a single electron beam in two-electron temperature space plasmas

Cited by 7 publications

References 29 publications

The effect of a warm electron beam on slow electron-acoustic solitons

The effect of a warm electron beam on slow electron-acoustic solitons

High and low frequency instabilities driven by counter-streaming electron beams in space plasmas

A particle-in-cell approach to obliquely propagating electrostatic waves

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