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Title: Nonlinear stability of magnetic islands in a rotating helical plasma

Abstract

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.

Authors:
; ;  [1];  [2]
  1. National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan)
  2. Japan Atomic Energy Agency, Rokkasho, Aomori 039-3212 (Japan)
Publication Date:
OSTI Identifier:
22072637
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 19; Journal Issue: 12; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

Nishimura, S, Toda, S, Narushima, Y, and Yagi, M. Nonlinear stability of magnetic islands in a rotating helical plasma. United States: N. p., 2012. Web. doi:10.1063/1.4773041.
Nishimura, S, Toda, S, Narushima, Y, & Yagi, M. Nonlinear stability of magnetic islands in a rotating helical plasma. United States. https://doi.org/10.1063/1.4773041
Nishimura, S, Toda, S, Narushima, Y, and Yagi, M. 2012. "Nonlinear stability of magnetic islands in a rotating helical plasma". United States. https://doi.org/10.1063/1.4773041.
@article{osti_22072637,
title = {Nonlinear stability of magnetic islands in a rotating helical plasma},
author = {Nishimura, S and Toda, S and Narushima, Y and Yagi, M},
abstractNote = {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.},
doi = {10.1063/1.4773041},
url = {https://www.osti.gov/biblio/22072637}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 12,
volume = 19,
place = {United States},
year = {2012},
month = {12}
}