Progress in theory of instabilities in a rotating plasma

Mikhaǐlovskiǐ, A. B.; Lominadze, J. G.; Churikov, A. P.; Pustovitov, V. D.

doi:10.1134/s1063780x09040035

Cited by 89 publications

(105 citation statements)

References 72 publications

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“…3 After initially investigating the MTI in a horizontal magnetic field, 1 Balbus studied the combination of MTI and magnetorotational instability ͑MRI͒ in a diluted plasma 4 and found that the criterion for convective instability went from one of upwardly decreasing entropy to one of upwardly decreasing temperature. Such a coupling effect was also investigated by Mikhailovskii et al 5,6 Parrish and Stone used numerical magnetohydrodynamic ͑MHD͒ simulation to investigate the nonlinear evolution and saturation of the MTI of atmospheres in two and three dimensions, respectively. They found that the linear growth rates measured in the simulation agreed well with the weakfield dispersion relationship, and saturation results in an atmosphere with different vertical structure were dependent on the boundary conditions.…”

Section: Coupling Of Kelvin-helmholtz Instability and Buoyancy Instabmentioning

confidence: 91%

Coupling of Kelvin–Helmholtz instability and buoyancy instability in a thermally laminar plasma

Ren

Dong

et al. 2011

Physics of Plasmas

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Thermal convective instability is investigated in a thermally stratified plasma in the presence of shear flow, which is known to give rise to the Kelvin–Helmholtz (KH) instability. We examine how the KH instability and magnetothermal instability (MTI) affect each other. Based on the sharp boundary model, the KH instability coupled with the MTI is studied. We present the growth rate and instability criteria. The shear flow is shown to significantly alter the critical condition for the occurrence of thermal convective instability.

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Section: Coupling Of Kelvin-helmholtz Instability and Buoyancy Instabmentioning

confidence: 91%

Coupling of Kelvin–Helmholtz instability and buoyancy instability in a thermally laminar plasma

Ren

Dong

et al. 2011

Physics of Plasmas

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“…Unfortunately, such flows often are unstable in magnetized plasma. This is particularly concerned to the flows with a large Hall parameter since hydrodynamic motions in such plasma typically are unstable even in the presence of a weak shear (see, e. g., [19][20][21]). As a result, a formation of the chemical spots is unlikely if there are hydrodynamic motions even with a weak shear.…”

Section: Discussionmentioning

confidence: 99%

“…Integrating the s-component of Eq. (19) and taking into account that the temperature is constant in our model, we obtain n = n 0 1 + β…”

Section: Element Spots Caused By Electric Currentsmentioning

confidence: 99%

Diffusion in plasma: The Hall effect, compositional waves, and chemical spots

Урпин

2017

Plasma Phys. Rep.

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We consider diffusion caused by a combined influence of the electric current and Hall effect, and argue that such diffusion can form inhomogeneities of a chemical composition in plasma. The considered mechanism can be responsible for a formation of element spots in laboratory and astrophysical plasmas. This current-driven diffusion can be accompanied by propagation of a particular type of waves in which the impurity number density oscillates alone. These compositional waves exist if the magnetic pressure in plasma is much greater than the gas pressure.

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“…This conclusion applies for collisionless AD plasmas (having in particular particle densities within the range mentioned earlier) which are strongly-magnetized and simultaneously gravitationally-bound . Since fluid descriptions of these plasmas can only be arrived at on the basis of the present Vlasov-Maxwell statistical description, also MHD instabilities, such as the axisymmetric MRI [2,20], the axisymmetric TMI (see for example [9][10][11]), and axisymmetric instabilities driven by temperature anisotropy (e.g., the firehose instability [21]) remain definitely forbidden for collisionless plasmas under these conditions.…”

Section: Msmentioning

confidence: 99%

Absolute Stability of Axisymmetric Perturbations in Strongly Magnetized Collisionless Axisymmetric Accretion Disk Plasmas

2012

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The physical mechanism responsible for driving accretion flows in astrophysical accretion disks is commonly thought to be related to the development of plasma instabilities and turbulence. A key question is therefore the determination of consistent equilibrium configurations for accretion-disk plasmas and investigation of their stability properties. In the case of collisionless plasmas kinetic theory provides the appropriate theoretical framework. This paper presents a kinetic description of low-frequency and long-wavelength axisymmetric electromagnetic perturbations in non-relativistic, strongly-magnetized and gravitationally-bound axisymmetric accretion-disk plasmas in the collisionless regime. The analysis, carried out within the framework of the Vlasov-Maxwell description, relies on stationary kinetic solutions of the Vlasov equation which allow for the simultaneous treatment of non-uniform fluid fields, stationary accretion flows and temperature anisotropies. It is demonstrated that, for such solutions, no axisymmetric unstable perturbations can exist occurring on characteristic time and space scales which are long compared with the Larmor gyration time and radius. Hence, these stationary configurations are actually stable against axisymmetric kinetic instabilities of this type. As a fundamental consequence, this rules out the possibility of having the axisymmetric magneto-rotational or thermal instabilities to arise in these systems.A fundamental issue in the physics of accretion disks (ADs) concerns the stability of equilibrium or quasi-stationary configurations occurring in AD plasmas. The observed transport phenomena giving rise to the accretion flow are commonly ascribed to the existence of instabilities and the subsequent development of fluid or MHD turbulence [1][2][3][4]. In principle, these can include both MHD phenomena (such as drift instabilities driven by gradients of the fluid fields) and kinetic ones (due to velocity-space anisotropies, including, for example, trapped-particle modes, cyclotron and Alfven waves, etc.). Possible candidates for the angular momentum transport mechanism are usually identified either with the magneto-rotational instability (MRI) [5][6][7] or the thermal instability (TMI) [8][9][10][11], caused by unfavorable gradients of rotation/shear and temperature respectively. The validity of the above identifications needs to be checked in this case, because they usually rely on incomplete physical descriptions, which ignore the microscopic (kinetic) plasma behavior. In fact, "stand-alone" fluid and MHD approaches which are not explicitly based on kinetic theory and/or do not start from consistent kinetic equilibria, may become inadequate or inapplicable for collisionless or weakly-collisional plasmas. Apart from possible gyrokinetic and finite Larmor-radius effects (which are typically not included for MRI and TMI), this concerns consistent treatment of the kinetic constraints which must be imposed on the fluid fields (see related discussion in Refs. [12,13]). This concerns,...

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Progress in theory of instabilities in a rotating plasma

Cited by 89 publications

References 72 publications

Coupling of Kelvin–Helmholtz instability and buoyancy instability in a thermally laminar plasma

Coupling of Kelvin–Helmholtz instability and buoyancy instability in a thermally laminar plasma

Diffusion in plasma: The Hall effect, compositional waves, and chemical spots

Absolute Stability of Axisymmetric Perturbations in Strongly Magnetized Collisionless Axisymmetric Accretion Disk Plasmas

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