MHD Stability in Flowing Plasmas: Connection between Fusion Plasma and Astrophysics Research

Furukawa, Masato; Yoshida, Zensho; Hirota, Mitsutomo; Krishan, V.

doi:10.1585/pfr.2.016

Cited by 3 publications

(3 citation statements)

References 25 publications

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“…an astrophysical accretion disc [46]. Adding the Brunt-Väisälä-frequency squared of an incompressible plasma perturbation R 2 ρ /ρ and the frequency squared R 2 of the magnetorotational instability [47,48] yields R(ρ 2 ) /ρ [49,50]. Instability resulting from a gradient in the kinetic energy may therefore be understood as a combination of the magnetorotational instability and the convective instability.…”

Section: The Kinetic Energy Term S Kmentioning

confidence: 99%

Stability of localized modes in rotating tokamak plasmas

Haverkort

Blank

2011

Plasma Phys. Control. Fusion

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The ideal magnetohydrodynamic stability is investigated of localized interchange modes in a large-aspect ratio tokamak plasma. The resulting stability criterion includes the effects of toroidal rotation and rotation shear and contains various well-known limiting cases. The analysis allows for a general adiabatic index, resulting in a stabilizing contribution from the convective effect. A further stabilizing effect from rotation exists when the angular frequency squared decreases radially more rapidly than the density. Flow shear, however, also decreases the stabilizing effect of magnetic shear through the KelvinHelmholtz mechanism. Numerical simulations reveal the merits and limitations of the performed local analysis.

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Section: The Kinetic Energy Term S Kmentioning

confidence: 99%

Stability of localized modes in rotating tokamak plasmas

Haverkort

Blank

2011

Plasma Phys. Control. Fusion

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“…The resulting E × B drift propels the filament, greatly enhancing convective perpendicular transport. Examples can be found in disparate contexts, including astrophysical plasmas such as accretion discs [2] and planetary magnetospheres [3], where the destabilizing force is typically of the centrifugal type, and laboratory plasmas [4,5], where the force density typically comes from magnetic pressure gradients. This issue is particularly relevant for magnetically confined fusion plasmas, as it determines the propagation of filamentary structures, which have become recognized as the dominant radial transport mechanism in the region between the closed magnetic field lines and the wall, known as Scrape-off Layer (SOL) [6][7][8][9].…”

mentioning

confidence: 99%

Experimental Validation of a Filament Transport Model in Turbulent Magnetized Plasmas

et al. 2015

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In a wide variety of natural and laboratory magnetized plasmas, filaments appear as a result of interchange instability. These convective structures substantially enhance transport in the direction perpendicular to the magnetic field. According to filament models, their propagation may follow different regimes depending on the parallel closure of charge conservation. This is of paramount importance in magnetic fusion plasmas, as high collisionality in the scrape-off layer may trigger a regime transition leading to strongly enhanced perpendicular particle fluxes. This work reports for the first time on an experimental verification of this process, linking enhanced transport with a regime transition as predicted by models. Based on these results, a novel scaling for global perpendicular particle transport in reactor relevant tokamaks such as ASDEX-Upgrade and JET is found, leading to important implications for next generation fusion devices.

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“…Taking the inner product of Eqs. (56) or (58) with n ⁄ and integrating over the entire plasma volume gives, solving for x [58,60] …”

Section: Stabilitymentioning

confidence: 99%

The Brunt–Väisälä frequency of rotating tokamak plasmas

Haverkort

Blank

Koren

2012

Journal of Computational Physics

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a b s t r a c tThe continuous spectrum of analytical toroidally rotating magnetically confined plasma equilibria is investigated analytically and numerically. In the presence of purely toroidal flow, the ideal magnetohydrodynamic equations leave the freedom to specify which thermodynamic quantity is constant on the magnetic surfaces. Introducing a general parametrization of this quantity, analytical equilibrium solutions are derived that still posses this freedom. These equilibria and their spectral properties are shown to be ideally suited for testing numerical equilibrium and stability codes including toroidal rotation. Analytical expressions are derived for the low-frequency continuous Alfvén spectrum. These expressions still allow one to choose which quantity is constant on the magnetic surfaces of the equilibrium, thereby generalizing previous results. The centrifugal convective effect is shown to modify the lowest Alfvén continuum branch to a buoyancy frequency, or Brunt-Väisälä frequency. A comparison with numerical results for the case that the specific entropy, the temperature, or the density is constant on the magnetic surfaces yields excellent agreement, showing the usefulness of the derived expressions for the validation of numerical codes.

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MHD Stability in Flowing Plasmas: Connection between Fusion Plasma and Astrophysics Research

Cited by 3 publications

References 25 publications

Stability of localized modes in rotating tokamak plasmas

Stability of localized modes in rotating tokamak plasmas

Experimental Validation of a Filament Transport Model in Turbulent Magnetized Plasmas

The Brunt–Väisälä frequency of rotating tokamak plasmas

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