Plasma Response to Strongly Sheared Flow

Amatucci, W. E.; Walker, D. N.; Ganguli, G.; Antoniades, J. A.; Duncan, D.; Bowles, Jeffrey H.; Gavrishchaka, Valeriy V.; Koepke, M. E.

doi:10.1103/physrevlett.77.1978

Cited by 95 publications

(77 citation statements)

References 34 publications

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“…Whereas the Doppler shift is typically greater than 1.5ω ci in previous reports of upshifting IEDD waves (Amatucci et al, 1996;, the maximum Doppler shift here is 0.2ω ci . Measurements indicate that ω 1 is less than ω ci and in the neighborhood of 0.9ω ci , as estimated from 1.14ω ci − 0.2ω ci .…”

Section: Discussionmentioning

confidence: 71%

“…In recent experiments on Inhomogeneous Energy-Density Driven (IEDD) waves (Ganguli et al, 1985;Koepke et al, 1994;Amatucci et al, 1996;, quantitative comparisons with theoretical predictions were obtained (Koepke et al, 1995;1998a;Amatucci et al, 1998;Carroll et al, 1998;Peñano et al, 1998). Beyond verifying the existence of the excitation mechanism, Correspondence to: M. E. Koepke (mkoepke@wvu.edu) these comparisons reinforced detailed aspects of the theoretical model and also stimulated refinements and an expanded awareness of the details of the model.…”

Section: Introductionmentioning

confidence: 87%

“…ω r /ω ci ≈ 0.3). For even larger values of k θ or ν E , k θ ν E can exceed ω 1 so that ω r and ω 1 have opposite signs and the observed mode frequency appears to increase with increasing ν E (Amatucci et al, 1996). Conceptually, such a frequency upshift is actually a frequency downshift of greater than 100%.…”

Section: Experimental Approachmentioning

confidence: 99%

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Resonant-to-nonresonant transition in electrostatic ion-cyclotron wave phase velocity

Carroll

Koepke

Zintl

et al. 2003

Nonlin. Processes Geophys.

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Abstract. Because of the implications for plasmas in the laboratory and in space, attention has been drawn to inhomogeneous energy-density driven (IEDD) waves that are sustained by velocity-shear-induced inhomogeneity in crossfield plasma flow. These waves have a frequency ω r in the lab frame within an order of magnitude of the ion gyrofrequency ω ci , propagate nearly perpendicular to the magnetic field (k z /k ⊥ 1), and can be Landau resonant (0 < ω 1 /k z < ν d ) with a parallel drifting electron population (drift speed ν d ), where subscripts 1 and r indicate frequency in the frame of flowing ions and in the lab frame, respectively, and k z is the parallel component of the wavevector. A transition in phase velocity from 0 < ω 1 /k z < ν d to 0 > ω 1 /k z > ν d for a pair of IEDD eigenmodes is observed as the degree of inhomogeneity in the transverse E × B flow is increased in a magnetized plasma column. For weaker velocity shear, both eigenmodes are dissipative, i.e. in Landau resonance, with k z ν d > 0. For stronger shear, both eigenmodes become reactive, with one's wavevector component k z remaining parallel, but with ω 1 /k z > ν d , and the other's wavevector component k z becoming anti-parallel, so that 0 > ω 1 /k z . For both eigenmodes, the transition (1) involves a small frequency shift and (2) does not involve a sign change in the wave energy density, which is proportional to ω r ω 1 , both of which are previously unrecognized aspects of inhomogeneous energydensity driven waves.

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Section: Discussionmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 87%

See 1 more Smart Citation

Resonant-to-nonresonant transition in electrostatic ion-cyclotron wave phase velocity

Carroll

Koepke

Zintl

et al. 2003

Nonlin. Processes Geophys.

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“…In spite of a long history of investigations there are many important motivations which still attract attention to different branches of physics, namely astrophysics (Arons et al, 1976), plasma fusion (Finn, 1993), space (Amatucci et al, 1996;Penano et al, 1998), atmospheric (Sazonov, 1991) and geophysics (Wilcock and Whitehead, 1991), etc. The primary source by which this instability is triggered is the gravitational force acting on an inverted density gradient (e.g.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear saturation of Rayleigh-Taylor instability and generation of shear flow in equatorial spread-F plasma

Chakrabarti

Lakhina

2001

Nonlin. Processes Geophys.

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Abstract. An analysis of low order mode coupling equations is used to describe the nonlinear behavior of the RayleighTaylor (RT) instability in the equatorial ionosphere. The nonlinear evolution of RT instability leads to the development of shear flow. It is found that there is an interplay between the nonlinearity and the shear flow which compete with each other and saturate the RT mode, both in the collisionless and collisional regime. However, the nonlinearly saturated state, normally known as vortices or bubbles, may not be stable. Under certain condition these bubbles are shown to be unstable to short scale secondary instabilities that are driven by the large gradients which develop within these structures. Some understanding of the role of collisional nonlinearity in the shear flow generations is also discussed.

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“…The Rayleigh-Taylor (RT) instability has been extensively studied in a wide range of physical context both experimentally and theoretically (Amatucci et al, 1996;Aron et al, 1976). The density fluctuations in the nighttime equatorial F-region of the ionosphere, commonly referred to as Equatorial Spread-F (ESF), have been a topic of active research in the last few decades.…”

Section: Introductionmentioning

confidence: 99%

Collisional Rayleigh-Taylor instability and shear-flow in equatorial Spread-F plasma

Chakrabarti

Lakhina²

2003

Ann. Geophys.

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Abstract. Collisional Rayleigh-Taylor (RT) instability is considered in the bottom side of the equtorial F-region. By a novel nonmodal calculation it is shown that for an applied shear flow in equilibrium, the growth of the instability is considerably reduced. Finite but small amounts of diffusion enhances the stabilization process. The results may be relevant to the observations of long-lived irregularities at the bottomside of the F-layer.

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Plasma Response to Strongly Sheared Flow

Cited by 95 publications

References 34 publications

Resonant-to-nonresonant transition in electrostatic ion-cyclotron wave phase velocity

Resonant-to-nonresonant transition in electrostatic ion-cyclotron wave phase velocity

Nonlinear saturation of Rayleigh-Taylor instability and generation of shear flow in equatorial spread-F plasma

Collisional Rayleigh-Taylor instability and shear-flow in equatorial Spread-F plasma

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