Absence of Complete Finite-Larmor-Radius Stabilization in Extended MHD

Zhu, Ping; Schnack, D. D.; Ebrahimi, F.; Zweibel, Ellen G.; Suzuki, M.; Hegna, C. C.; Sovinec, C. R.

doi:10.1103/physrevlett.101.085005

Cited by 35 publications

(47 citation statements)

References 15 publications

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“…The previous investigations of the magnetic RT instability and nonlinear structures of flute waves were restricted to the long wavelength limit when the wave spatial scale is larger than the ion Larmor radius. Therefore, the conclusions [4,5] on the possible absence of complete FLR stabilization in the wavelength region where the equations are not applicable, remained doubtful. Recently, in order to overcome this difficulty, the theory of flute waves, driven by the RT instability, was extended to the case of arbitrary spatial scales [6,7].…”

Section: Introductionmentioning

confidence: 99%

“…About 50 years ago it was shown [1][2][3] that the finite Larmor radius (FLR) effects have a stabilizing influence on this instability. However, the subsequent numerical simulations and detailed theoretical investigations [4,5] showed that complete FLR stabilization is not always attainable. The previous investigations of the magnetic RT instability and nonlinear structures of flute waves were restricted to the long wavelength limit when the wave spatial scale is larger than the ion Larmor radius.…”

Section: Introductionmentioning

confidence: 99%

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Stabilization of magnetic curvature-driven Rayleigh–Taylor instabilities

et al. 2011

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Abstract. The finite ion Larmor radius (FLR) stabilization of the magnetic curvaturedriven Rayleigh-Taylor (MCD RT) instability in a low beta plasma with nonzero ion temperature gradient is investigated. Finite electron temperature effects and ion temperature perturbations are incorporated. A new set of nonlinear equations for flute waves with arbitrary wavelengths as compared with the ion Larmor radius in a plasma with curved magnetic field lines is derived. Particular attention is paid to the waves with spatial scales of the order of the ion Larmor radius. In the linear limit, a Fourier transform of these equations yields an improved dispersion relation for flute waves. The dependence of the MCD RT instability growth rate on the equilibrium plasma parameters and the wavelengths is studied. The condition for which the instability cannot be stabilized by the FLR effects is found.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stabilization of magnetic curvature-driven Rayleigh–Taylor instabilities

et al. 2011

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“…The extended MHD equations have been widely used to study interchange instability, because they are able to be applied to the complicated magnetic confined closed systems. 6,7 The FLR effects on an interchange instability are also important in an open system such as a tandem mirror. [8][9][10][11][12] The generalized Ohm's law and gyroviscosity in the extended MHD equation were derived theoretically.…”

Section: Introductionmentioning

confidence: 99%

“…5,13 Recently, it has been reported that the complete FLR stabilization of the interchange mode may not be attainable by the gyroviscosity or generalized Ohm's law alone in the frame work of extended MHD. 7 The stability boundary of an interchange instability with FLR was determined by the kinetic analysis. 4,14 Thus, it is worth verifying with the help of a particle simulation that the interchange instability can be really stabilized by FLR effects completely.…”

Section: Introductionmentioning

confidence: 99%

Ion finite Larmor radius effects on the interchange instability in an open system

et al. 2013

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A particle simulation of an interchange instability was performed by taking into account the ion finite Larmor radius (FLR) effects. It is found that the interchange instability with large FLR grows in two phases, that is, linearly growing phase and the nonlinear phase subsequent to the linear phase, where the instability grows exponentially in both phases. The linear growth rates observed in the simulation agree well with the theoretical calculation. The effects of FLR are usually taken in the fluid simulation through the gyroviscosity, the effects of which are verified in the particle simulation with large FLR regime. The gyroviscous cancellation phenomenon observed in the particle simulation causes the drifts in the direction of ion diamagnetic drifts.

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“…Zhu et al have shown that the complete stabilization is absent for a certain b-value (ratio of the thermal pressure to the magnetic pressure), though the growth rate at high wave numbers are reduced significantly. 9 More recently, Xi et al have shown for the ion density gradient mode of magnetically confined plasma 10 and the authors have shown for the R-T mode 11 independently that the high modes can be stabilized by the combination of the two-fluid and the gyro-viscous terms, not by only one of them. It has been also shown in Ref.…”

Section: Introductionmentioning

confidence: 99%

Formation of large-scale structures with sharp density gradient through Rayleigh-Taylor growth in a two-dimensional slab under the two-fluid and finite Larmor radius effects

et al. 2015

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Two-fluid and the finite Larmor effects on linear and nonlinear growth of the Rayleigh-Taylor instability in a two-dimensional slab are studied numerically with special attention to high-wave-number dynamics and nonlinear structure formation at a low β-value. The two effects stabilize the unstable high wave number modes for a certain range of the β-value. In nonlinear simulations, the absence of the high wave number modes in the linear stage leads to the formation of the density field structure much larger than that in the single-fluid magnetohydrodynamic simulation, together with a sharp density gradient as well as a large velocity difference. The formation of the sharp velocity difference leads to a subsequent Kelvin-Helmholtz-type instability only when both the two-fluid and finite Larmor radius terms are incorporated, whereas it is not observed otherwise. It is shown that the emergence of the secondary instability can modify the outline of the turbulent structures associated with the primary Rayleigh-Taylor instability.

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Absence of Complete Finite-Larmor-Radius Stabilization in Extended MHD

Cited by 35 publications

References 15 publications

Stabilization of magnetic curvature-driven Rayleigh–Taylor instabilities

Stabilization of magnetic curvature-driven Rayleigh–Taylor instabilities

Ion finite Larmor radius effects on the interchange instability in an open system

Formation of large-scale structures with sharp density gradient through Rayleigh-Taylor growth in a two-dimensional slab under the two-fluid and finite Larmor radius effects

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