Mercier Stability Improvement in Nonlinear Development of LHD Plasma

Ichiguchi, K.; Carreras, B. A.

doi:10.1585/pfr.3.s1033

Cited by 12 publications

(22 citation statements)

References 6 publications

(11 reference statements)

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“…Kink and tearing modes with m = 2 and n = 1 have been examined previously in configurations of LHDlike plasma similar to the present ones [11]. No unstable non-resonant mode was obtained in those configurations, whereas non-resonant modes appear in the present ones.…”

Section: Discussionsupporting

confidence: 74%

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MHD Instabilities in Current Carrying Heliotron Plasmas

Yamada

Nakamura

Kondo

2010

Plasma and Fusion Research

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Instabilities in low beta l = 2 heliotron plasmas with peaked toroidal current density profiles are investigated using resistive reduced magnetohydrodynamic equations. Such heliotron plasmas can have a nonmonotonic rotational transformῑ profile with twoῑ = 2/3 rational surfaces. When the distance between the resonant surfaces is large, resistive instabilities can be found. Current-driven ideal modes with larger growth rates appear when the minimum of the rotational transform becomes just above the rational number 2/3 and there is no resonant surface. The existence of this non-resonant mode is explained by the expression for the current-driven term of the plasma potential energy.

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Section: Discussionsupporting

confidence: 74%

“…There is no pressure-driven contribution to the potential energy due to zero-beta in the case of Ref. [11], and we consider that the zero-beta condition prevents non-resonant modes from becoming unstable. It is pointed out that pressure gradient is not necessary for the instability of nonresonant modes.…”

Section: Discussionmentioning

confidence: 99%

MHD Instabilities in Current Carrying Heliotron Plasmas

Yamada

Nakamura

Kondo

2010

Plasma and Fusion Research

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“…In order to investigate the property of the pressure driven mode in the case with the RMP, particularly the relation between the stability and the mode extension in the poloidal direction, we examine the behavior of the mode in the artificial change of the viscosity. In general, the viscosity has a stabilizing contribution to pressure driven modes [7,8]. Since higher mode components are stabilized more effectively, only lower components can survive as the viscosity is increased.…”

Section: Effects Of Rmp On Pressure Driven Modementioning

confidence: 99%

Three-Dimensional Numerical Analysis of Pressure Driven Mode in RMP-Imposed LHD Plasma

Ichiguchi

Suzuki

Sato

et al. 2014

Plasma and Fusion Research

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Property of pressure driven modes in Large Helical Device (LHD) plasmas with a resonant magnetic perturbation (RMP) is numerically studied. Particularly, we analyze three-dimensional (3D) RMP effects on the linear magnetohydrodynamic (MHD) stability of the modes. For this purpose, 3D numerical codes are utilized for both calculations of an equilibrium including an RMP generating an m = 1/n = 1 magnetic island and the stability of the perturbations resonant at theί = 1 surface. Here, m and n are the poloidal and the toroidal mode numbers, respectively, andί denotes rotational transform. Owing to the RMP, the pressure driven mode is localized around the X-point of the island. The type of the mode structure changes from the interchange type to the ballooning type. This property is attributed to the fact that the equilibrium pressure gradient is larger at the X-point than at the O-point.

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“…6 There are also many simulation studies about the effect of the resistive interchange instability in the nonlinear saturation phase on the plasma confinement property. [7][8][9][10][11] The characteristics of the perturbed current due to the resistive interchange instability and the consequent magnetic island have been reported, although the reports are for the limited range of the b value and the S number. However, it is increasing for the demand of the systematical prediction of the characteristics of the resistive interchange instability, e.g., the magnetic island formation property, to interpret the LHD experiments results.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of magnetic island formation due to resistive interchange instability in helical plasma

et al. 2014

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Focusing attention on the magnetic island formation, we investigate the characteristics of the resistive interchange magnetohydrodynamics instabilities, which would limit a high beta operational regime in helical type fusion reactors. An introduction of a new index, i.e., the ratio of the magnetic fluctuation level to the radial displacement, enables us to make a systematic analysis on the magnetic island formation in the large helical device-like plasmas during the linear growth phase; (i) the interchange instability with the second largest growth rate makes the magnetic island larger than that with the largest growth rate when the amplitude of the radial displacement in both cases is almost the same as each other; (ii) applied to a typical tearing instability, the index is smaller than that for the interchange instability with the second largest growth rate

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Mercier Stability Improvement in Nonlinear Development of LHD Plasma

Cited by 12 publications

References 6 publications

MHD Instabilities in Current Carrying Heliotron Plasmas

MHD Instabilities in Current Carrying Heliotron Plasmas

Three-Dimensional Numerical Analysis of Pressure Driven Mode in RMP-Imposed LHD Plasma

Characteristics of magnetic island formation due to resistive interchange instability in helical plasma

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