Nonlinear stability of magnetic islands in a rotating helical plasma

Journal Article · Sat Dec 15 04:00:00 EST 2012 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4773041· OSTI ID:22072637

Nishimura, S; Toda, S; Narushima, Y ^[1]; Yagi, M ^[2]

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1. National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan)
2. Japan Atomic Energy Agency, Rokkasho, Aomori 039-3212 (Japan)

Coexistence of the forced magnetic reconnection by a resonant magnetic perturbation (RMP) and the curvature-driven tearing mode is investigated in a helical (stellarator) plasma rotated by helical trapped particle-induced neoclassical flows. A set of Rutherford-type equations of rotating magnetic islands and a poloidal flow evolution equation is revisited. Using the model, analytical expressions of criteria of spontaneous shrinkage (self-healing) of magnetic islands and sudden growth of locked magnetic islands (penetration of RMP) are obtained, where nonlinear saturation states of islands show bifurcation structures and hysteresis characteristics. Considering radial profile of poloidal flows across magnetic islands, it is found that the self-healing is driven by neoclassical viscosity even in the absence of micro-turbulence-induced anomalous viscosity. Effects of unfavorable curvature in stellarators are found to modify the critical values. The scalings of criteria are consistent with low-{beta} experiments in the large helical device.

• OSTI ID: 22072637
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 12 Vol. 19; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BIFURCATION
DISTURBANCES
FLOW MODELS
HELICAL CONFIGURATION
HYSTERESIS
LHD DEVICE
MAGNETIC ISLANDS
MAGNETIC RECONNECTION
NEOCLASSICAL TRANSPORT THEORY
NONLINEAR PROBLEMS
PLASMA
STELLARATORS
TEARING INSTABILITY
TURBULENCE
VISCOSITY