A hybrid Rayleigh-Taylor-current-driven coupled instability in a magnetohydrodynamically collimated cylindrical plasma with lateral gravity

Zhai, Xiang; Bellan, Paul M.

doi:10.1063/1.4943896

Cited by 13 publications

(15 citation statements)

References 39 publications

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“…These effects become important at small length scales such as the ion Larmor radius or the ion skin depth where MHD is no longer valid. For example, in a recent set of experiments involving a plasma jet, 7,10 a kinkinduced Rayleigh-Taylor instability 11 effectively narrowed the plasma column to the ion skin depth scale, transitioning from an MHD-governed system to a system governed by Hall and electron inertia effects. A strong suggestion that Hall and electron inertia terms were important was the observed emission of circularly polarized whistler waves in association with the reconnection.…”

Section: Introductionmentioning

confidence: 99%

A generalized two-fluid picture of non-driven collisionless reconnection and its relation to whistler waves

Yoon

Bellan

2017

Physics of Plasmas

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A generalized, intuitive two-fluid picture of 2D non-driven collisionless magnetic reconnection is described using results from a full-3D numerical simulation. The relevant two-fluid equations simplify to the condition that the flux associated with canonical circulation Q ¼ m e r Â u e þ q e B is perfectly frozen into the electron fluid. In the reconnection geometry, flux tubes defined by Q are convected with the central electron current, effectively stretching the tubes and increasing the magnitude of Q exponentially. This, coupled with the fact that Q is a sum of two quantities, explains how the magnetic fields in the reconnection region reconnect and give rise to strong electron acceleration. The Q motion provides an interpretation for other phenomena as well, such as spiked central electron current filaments. The simulated reconnection rate was found to agree with a previous analytical calculation having the same geometry. Energy analysis shows that the magnetic energy is converted and propagated mainly in the form of the Poynting flux, and helicity analysis shows that the canonical helicity Ð P Á Q dV as a whole must be considered when analyzing reconnection. A mechanism for whistler wave generation and propagation is also described, with comparisons to recent spacecraft observations. Published by AIP Publishing. [http://dx.

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Section: Introductionmentioning

confidence: 99%

A generalized two-fluid picture of non-driven collisionless reconnection and its relation to whistler waves

Yoon

Bellan

2017

Physics of Plasmas

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“…Their analysis showed that though these physics do not alter the threshold for instability, the ion-neutral collisions can vastly reduce the growth rate of the instability. Zhai & Bellan (2016) developed a model of a hybrid of the current-driven kink instability and the magnetic Rayleigh-Taylor instability in a flux tube to model the experimental findings of Moser & Bellan (2012), where they found this new geometry was able to explain the growth of the observed instability. For a detail investigation into many of the important process relating to the RayleighTaylor instability including the extension to stratified atmospheres, compressibility, inhomogeneity and continua see, for example, Goedbloed & Poedts (2004) and Goedbloed et al (2010).…”

Section: The Rayleigh-taylor Instability In Astrophysical Plasmamentioning

confidence: 99%

On the nature of the magnetic Rayleigh–Taylor instability in astrophysical plasma: the case of uniform magnetic field strength

Hillier

2016

Mon. Not. R. Astron. Soc.

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The magnetic Rayleigh-Taylor instability has been shown to play a key role in many astrophysical systems. The equation for the growth rate of this instability in the incompressible limit, and the most-unstable mode that can be derived from it, are often used to estimate the strength of the magnetic field that is associated with the observed dynamics. However, there are some issues with the interpretations given. Here we show that the class of most unstable modes k u for a given θ , the class of modes often used to estimate the strength of the magnetic field from observations, for the system leads to the instability growing as σ 2 = 1/2Agk u , a growth rate which is independent of the strength of the magnetic field and which highlights that small scales are preferred by the system, but not does not give the fastest growing mode for that given k. We also highlight that outside of the interchange (k · B = 0) and undular (k parallel to B) modes, all the other modes have a perturbation pair of the same wavenumber and growth rate that when excited in the linear regime can result in an interference pattern that gives field aligned filamentary structure often seen in 3D simulations. The analysis was extended to a sheared magnetic field, where it was found that it was possible to extend the results for a non-sheared field to this case. We suggest that without magnetic shear it is too simplistic to be used to infer magnetic field strengths in astrophysical systems.

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“…In a similar process to that seen in Isobe et al (2006), the nonlinear development led to magnetic reconnection. Zhai and Bellan (2016) developed linear theory to describe the growth of the hybrid of the current driven kink instability and the gravitationally driven magnetic Rayleigh-Taylor instability. They found that the combined instability grew significantly faster than either of the two individual instabilities by themselves.…”

Section: Plasma and Fluid Experimentsmentioning

confidence: 99%

The magnetic Rayleigh–Taylor instability in solar prominences

Hillier

2017

Rev. Mod. Plasma Phys.

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The magnetic Rayleigh-Taylor instability is a fundamental instability of many astrophysical systems, and recent observations are consistent with this instability developing in solar prominences. Prominences are cool, dense clouds of plasma that form in the solar corona that display a wide range of dynamics of a multitude of spatial and temporal scales, and two different phenomena that have been discovered to occur in prominences can be understood as resulting from the Rayleigh-Taylor instability. The first is that of plumes that rise through quiescent prominences from low density bubbles that form below them. The second is that of a prominence eruption that fragments as the material falls back to the solar surface. To identify these events as the magnetic Rayleigh-Taylor instability, a wide range of theoretical work, both numerical and analytical has been performed, though alternative explanations do exist. For both of these sets of observations, determining that they are created by the magnetic Rayleigh-Taylor instability has meant that the linear instability conditions and nonlinear dynamics can be used to make estimates of the magnetic field strength. There are strong connections between these phenomena and those in a number of other astro, space and plasma systems, making these observations very important for our understanding of the role of the RayleighTaylor instability in magnetised systems.

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A hybrid Rayleigh-Taylor-current-driven coupled instability in a magnetohydrodynamically collimated cylindrical plasma with lateral gravity

Cited by 13 publications

References 39 publications

A generalized two-fluid picture of non-driven collisionless reconnection and its relation to whistler waves

A generalized two-fluid picture of non-driven collisionless reconnection and its relation to whistler waves

On the nature of the magnetic Rayleigh–Taylor instability in astrophysical plasma: the case of uniform magnetic field strength

The magnetic Rayleigh–Taylor instability in solar prominences

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