Stability of localized modes in rotating tokamak plasmas

Haverkort, J.W.; Blank, H. J. de

doi:10.1088/0741-3335/53/4/045008

Cited by 9 publications

(20 citation statements)

References 62 publications

(172 reference statements)

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“…(49) resulting from a combination of the magneto-rotational instability and the convective effect of incompressible radial perturbations n w . This combination was previously found in both astrophysical [55,62] and tokamak plasmas [63,64].…”

Section: Potential Energysupporting

confidence: 78%

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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Section: Potential Energysupporting

confidence: 78%

The Brunt–Väisälä frequency of rotating tokamak plasmas

Haverkort

Blank

Koren

2012

Journal of Computational Physics

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“…In integrated form the effect first appeared in an analysis of the internal kink mode [5] where it was grouped with inertial terms and was denoted as "flutter." The effect also surfaced in more recent analyses [6,7]. In Ref.…”

Section: Introductionmentioning

confidence: 63%

“…[7] with growth rates of several tens of a percent of ω A0 on the magnetic axis. We use a rotation profile…”

Section: Simulationsmentioning

confidence: 99%

“…(1) is derived in Ref. [7] under the assumption that the Coriolis shift and the Doppler shifted mode frequency ω D = ω + n vanish. At marginal stability then V 2 = n 2 2 = −W , marginally satisfying Eq.…”

Section: Appendix C: Negative Energy Wavesmentioning

confidence: 99%

“…In Ref. [7] a stability criterion is derived for modes localized in the r direction, normal to the circular magnetic surfaces of a large aspect ratio tokamak plasma. For not too high rotation this result reads [7] …”

Section: Introductionmentioning

confidence: 99%

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Flow shear stabilization of rotating plasmas due to the Coriolis effect

Haverkort

Blank

2012

Phys. Rev. E

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A radially decreasing toroidal rotation frequency can have a stabilizing effect on nonaxisymmetric magnetohydrodynamic (MHD) instabilities. We show that this is a consequence of the Coriolis effect that induces a restoring pressure gradient force when plasma is perturbed radially. In a rotating cylindrical plasma, this Coriolis-pressure effect is canceled by the centrifugal effect responsible for the magnetorotational instability. In a magnetically confined toroidal plasma, a large aspect ratio expansion shows that only half of the effect is canceled. This analytical result is confirmed by numerical computations. When the plasma rotates faster toroidally in the core than near the edge, the effect can contribute to the formation of transport barriers by stabilizing MHD instabilities.

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Nonlinear interaction between double tearing mode and Kelvin–Helmholtz instability with different shear flows

Li,

Wang,

et al. 2023

Sci Rep

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The nonlinear interaction between the double tearing mode (DTM) and Kelvin–Helmholtz (KH) instabilities with different shear flow profiles has been numerically investigated via the use of a compressible magnetohydrodynamics (MHD) model. We focus on KH instabilities in weak and reversed magnetic shear plasmas with strong stabilizing effect of field line bending. Results show that KH instabilities coupled with DTMs occur in these plasmas and the KH mode dominates the instability dynamics, suggesting the crucial role of weak magnetic shear in the formation of high-mode harmonics. For symmetric flows, an asymmetric forced magnetic reconnection configuration is maintained during the growth phase, leading to interlocking of the modes. Additionally, this investigation of the DTM-KH instability interaction contributes to our understanding of the nonlinear reconnection mechanism in the regime of weak and reversed magnetic shear plasmas, which is relevant for astrophysical and fusion studies.

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Stability of localized modes in rotating tokamak plasmas

Cited by 9 publications

References 62 publications

The Brunt–Väisälä frequency of rotating tokamak plasmas

The Brunt–Väisälä frequency of rotating tokamak plasmas

Flow shear stabilization of rotating plasmas due to the Coriolis effect

Nonlinear interaction between double tearing mode and Kelvin–Helmholtz instability with different shear flows

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