Sheared-Flow-Driven Electrostatic Waves in Laboratory and Space Plasmas

Koepke, M. E.

doi:10.1238/physica.topical.107a00182

Cited by 14 publications

(13 citation statements)

References 86 publications

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“…Interestingly, laboratory experiments demonstrated that ion temperature anisotropy can significantly increase the growth rate of shear-driven ion-acoustic (IA) waves (Koepke, 2004;Koepke et al, 2003). The increase in the growth rate with thermal anisotropy suggests that the plasma was unstable to smaller critical drifts.…”

Section: Introductionmentioning

confidence: 99%

Ion temperature anisotropy effects on threshold conditions of a shear-modified current driven electrostatic ion-acoustic instability in the topside auroral ionosphere

et al. 2013

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Temperature anisotropies may be encountered in space plasmas when there is a preferred direction, for instance, a strong magnetic or electric field. In this paper, we study how ion temperature anisotropy can affect the threshold conditions of a shear-modified current driven electrostatic ion-acoustic (CDEIA) instability. In particular, this communication focuses on instabilities in the context of topside auroral F-region situations and in the limit where finite Larmor radius corrections are small. We derived a new fluid-like expression for the critical drift which depends explicitly on ion anisotropy. More importantly, for ion to electron temperature ratios typical of F-region, solutions of the kinetic dispersion relation show that ion temperature anisotropy may significantly lower the drift threshold required for instability. In some cases, a perpendicular to parallel ion temperature ratio of 2 and may reduce the relative drift required for the onset of instability by a factor of approximately 30, assuming the ion-acoustic speed of the medium remains constant. Therefore, the ion temperature anisotropy should be considered in future studies of ion-acoustic waves and instabilities in the high-latitude ionospheric F-region

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Section: Introductionmentioning

confidence: 99%

Ion temperature anisotropy effects on threshold conditions of a shear-modified current driven electrostatic ion-acoustic instability in the topside auroral ionosphere

et al. 2013

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“…Under that condition, we have jz e j ( 1, and the term De e (k, x), which determines the effect of electron Landau damping, may be neglected in Eq. (12). The negative term containing the ion diamagnetic drift velocity in Eq.…”

Section: Hydrodynamic Ionsmentioning

confidence: 99%

“…INTRODUCTION Shear in magnetic-field-aligned (i.e., parallel) plasma flow can be found in space, 1-3 fusion, 4-8 and laboratory [9][10][11][12][13][14][15][16] plasma. Ionospheric regions of inhomogeneous parallel plasma flow can map magnetically to magnetospheric regions of large-scale field-aligned currents, resulting in broadband electrostatic noise in the auroral zone of geospace.…”

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confidence: 99%

Ion-temperature-gradient sensitivity of the hydrodynamic instability caused by shear in the magnetic-field-aligned plasma flow

Mikhailenko

Lee

et al. 2014

Physics of Plasmas

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The cross-magnetic-field (i.e., perpendicular) profile of ion temperature and the perpendicular profile of the magnetic-field-aligned (parallel) plasma flow are sometimes inhomogeneous for space and laboratory plasma. Instability caused either by a gradient in the ion-temperature profile or by shear in the parallel flow has been discussed extensively in the literature. In this paper, (1) hydrodynamic plasma stability is investigated, (2) real and imaginary frequency are quantified over a range of the shear parameter, the normalized wavenumber, and the ratio of density-gradient and ion-temperature-gradient scale lengths, and (3) the role of inverse Landau damping is illustrated for the case of combined ion-temperature gradient and parallel-flow shear. We find that increasing the ion-temperature gradient reduces the instability threshold for the hydrodynamic parallel-flow shear instability, also known as the parallel Kelvin-Helmholtz instability or the D'Angelo instability. We also find that a kinetic instability arises from the coupled, reinforcing action of both free-energy sources. For the case of comparable electron and ion temperature, we illustrate analytically the transition of the D'Angelo instability to the kinetic instability as (a) the shear parameter, (b) the normalized wavenumber, and (c) the ratio of density-gradient and ion-temperature-gradient scale lengths are varied and we attribute the changes in stability to changes in the amount of inverse ion Landau damping. We show that near a normalized wavenumber k⊥ρi of order unity (i) the real and imaginary values of frequency become comparable and (ii) the imaginary frequency, i.e., the growth rate, peaks.

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“…Sheared plasma flows parallel and perpendicular to the equilibrium magnetic field direction are ubiquitous in space and laboratory [1][2][3][4][5][6] and are considered to play an important role in the generation of plasma instabilities and turbulence. Long ago, 7 it was pointed out that the sheared plasma flow parallel to the external magnetic field can give rise to a purely growing electrostatic instability.…”

Section: Introductionmentioning

confidence: 99%

Short scale electrostatic vortices driven by electrons sheared flow parallel to external magnetic field in heavier ion plasmas

Ahmad

Saleem

2012

Physics of Plasmas

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Nonlinear equations for an electrostatic perturbation in hybrid frequency range are derived in a magnetized heavier ion plasma assuming that the electrons are flowing with a sheared velocity along the initial external constant magnetic field B 0zẑ . As a result of this current, the total zero-order magnetic field becomes sheared as B 0 ¼ B 0zẑ þ B 0y ðxÞŷ. Such a system can give rise to unstable electrostatic waves under certain conditions. The solutions of the nonlinear equations are obtained in the form of dipolar vortices, which can play an important role in plasma transport across field lines. This work can be useful for the future experiments on sheared electron flows. V C 2012 American Institute of Physics. [http://dx.

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Sheared-Flow-Driven Electrostatic Waves in Laboratory and Space Plasmas

Cited by 14 publications

References 86 publications

Ion temperature anisotropy effects on threshold conditions of a shear-modified current driven electrostatic ion-acoustic instability in the topside auroral ionosphere

Ion temperature anisotropy effects on threshold conditions of a shear-modified current driven electrostatic ion-acoustic instability in the topside auroral ionosphere

Ion-temperature-gradient sensitivity of the hydrodynamic instability caused by shear in the magnetic-field-aligned plasma flow

Short scale electrostatic vortices driven by electrons sheared flow parallel to external magnetic field in heavier ion plasmas

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