Present state of the theory of the MHD equilibrium and stability of stellarator plasmas

Коврижных, Л. М.; Shchepetov, S. V.

doi:10.1070/pu1986v029n04abeh003308

Cited by 19 publications

(34 citation statements)

References 49 publications

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“…[6] has been observed in various stellarator experiments [7,8,9,10]. In these results, geometrical deformations associated with the Shafranov shift result in configurations which are stable with respect to Mercier modes as pressure is increased.…”

Section: Introductionsupporting

confidence: 56%

“…The identities eqn (4,5,6) are useful for examining the numerical accuracy of both the original equilibrium and the transformation to Boozer coordinates.…”

Section: Numerical Implementationmentioning

confidence: 99%

“…To obtain an expression for the quantity D the constraints imposed by requiring the perturbations satisfy eqn (5,6) and force balance are utilized. This results in an equation for D…”

Section: Theorymentioning

confidence: 99%

See 2 more Smart Citations

Marginal stability boundaries for infinite-n ballooning modes in a quasiaxisymmetric stellarator

Hudson

Hegna

2003

Physics of Plasmas

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A method for computing the ideal magnetohydrodynamic (MHD) stability boundaries in three-dimensional equilibria is employed. Following Hegna and Nakajima [Phys. Plasmas 5, 1336 (1998)], a two-dimensional family of equilibria is constructed by perturbing the pressure and rotational-transform profiles in the vicinity of a flux surface for a given stellarator equilibrium. The perturbations are constrained to preserve the MHD equilibrium condition. For each perturbed equilibrium, the infinite-n ballooning stability is calculated. Marginal stability diagrams are thus constructed that are analogous to (s,α) diagrams for axisymmetric configurations. A quasiaxisymmetric stellarator is considered. Calculations of stability boundaries generally show regions of instability can occur for either sign of the average magnetic shear. Additionally, regions of second-stability are present.

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Section: Introductionsupporting

confidence: 56%

“…The identities eqn (4,5,6) are useful for examining the numerical accuracy of both the original equilibrium and the transformation to Boozer coordinates.…”

Section: Numerical Implementationmentioning

confidence: 99%

See 1 more Smart Citation

Marginal stability boundaries for infinite-n ballooning modes in a quasiaxisymmetric stellarator

Hudson

Hegna

2003

Physics of Plasmas

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“…The MHD equilibrium and plasma stability in this configuration are well understood. The vacuum magnetic configura tion has a magnetic hill; however, in the presence of plasma, a magnetic well forms in the plasma core due to plasma self stabilization [15]. In this case, ideal interchange MHD modes in the plasma core are stabi lized by the magnetic well, whereas closer to the plasma edge, they are stabilized by the shear.…”

Section: Experimental Setup and Summarymentioning

confidence: 99%

Long-range spatial correlations in the turbulent edge plasma of the L-2M stellarator

2013

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Long range spatial correlations in the turbulent plasma of the L 2M stellarator were revealed experimentally, and their relation to the geometry of magnetic surfaces was analyzed (Plasma Phys. Control. Fusion 50, 045001 (2008)). The operation modes of the facility in which fast transport transitions in plasma are possible were studied. Upon these transitions, the turbulence level is found to decrease substantially. It is shown that long range spatial correlations are typical of relatively narrow frequency ranges. In particular, before a transport transition, such frequency ranges are f ~ 30-40 kHz and f ~ 1-3 kHz. After the transition, long range spatial correlations in the frequency range of f ~ 30-40 kHz disappear due to a significant decrease in the turbulence level in this frequency range. At the same time, correlations in the low frequency range are retained and new correlations at frequencies of f ~ 6-12 kHz occur. It is found that global electromagnetic oscillations in the frequency range of f ~ 1-3 kHz are related to the m/n = 0/0 perturbation and its toroidal satellites (here, m and n are the poloidal and toroidal mode numbers, respectively). It is also shown that, after the transport transition, a three dimensional localized electromagnetic mode at the frequency of the geodesic acoustic mode governed by the average magnetic field curvature is excited. At higher frequencies typical of a geodesic acoustic mode related to the three dimensional curvature of the magnetic field, no long range spa tial correlations were observed both before and after the transport transition.

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“…The present experiments were carried out in low-beta plasmas β(r s /r = 0) ≈ 0.2%, where stability calculations show that ideal MHD modes are stable †. The stability criteria for pressure-driven-resistive MHD modes with poloidal number m 1 and for small beta values is given by (Kovrizhnykh and Shchepetov 1981)…”

Section: Discussionmentioning

confidence: 99%

Statistical properties and radial structure of plasma turbulence in the boundary region of the L2-M stellarator

Batanov

Fedianin

Kharchev

et al. 1998

Plasma Phys. Control. Fusion

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The structure of fluctuations and turbulent transport have been investigated in the plasma boundary region of the L2-M stellarator. Normalized fluctuation levels are in the range (3-20)% and fluctuations are dominated by frequencies below 300 kHz. In the edge plasma region located inside the last closed magnetic flux surface the radial coherence of fluctuations is due to high-frequency fluctuations (>100 kHz). The poloidal coherence is dominated by low frequencies. Linear coupling of resistive interchange modes is considered a candidate to explain the existence of highly radially correlated fluctuations in the high-frequency range.

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Present state of the theory of the MHD equilibrium and stability of stellarator plasmas

Cited by 19 publications

References 49 publications

Marginal stability boundaries for infinite-n ballooning modes in a quasiaxisymmetric stellarator

Marginal stability boundaries for infinite-n ballooning modes in a quasiaxisymmetric stellarator

Long-range spatial correlations in the turbulent edge plasma of the L-2M stellarator

Statistical properties and radial structure of plasma turbulence in the boundary region of the L2-M stellarator

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