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Title: Simulation of non-resonant internal kink mode with toroidal rotation in the National Spherical Torus Experiment

Plasmas in spherical and conventional tokamaks, with weakly reversed shear q profile and minimum q above but close to unity, are susceptible to an non-resonant (m,n) = (1,1) internal kink mode. This mode can saturate and persist and can induce a (2,1) seed island for Neoclassical Tearing Mode. [Breslau et al. Nucl. Fusion 51, 063027 (2011)]. The mode can also lead to large energetic particle transport and significant broadening of beam-driven current. Motivated by these important effects, we have carried out extensive nonlinear simulations of the mode with finite toroidal rotation using parameters and profiles of an NTSX plasma with a weakly reversed shear profile. The numerical results show that, at the experimental level, plasma rotation has little effect on either equilibrium or linear stability. However, rotation can significantly influence the nonlinear dynamics of the (1,1) mode and the induced (2,1) magnetic island. The simulation results show that a rotating helical equilibrium is formed and maintained in the nonlinear phase at finite plasma rotation. In contrast, for non-rotating cases, the nonlinear evolution exhibits dynamic oscillations between a quasi-2D state and a helical state. Furthermore, the effects of rotation are found to greatly suppress the (2,1) magnetic island even at amore » low level.« less
Authors:
;  [1] ; ;  [2] ;  [3]
  1. School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)
  2. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
  3. Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States)
Publication Date:
OSTI Identifier:
22227951
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 7; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; KINK INSTABILITY; MAGNETIC ISLANDS; MAGNETOHYDRODYNAMICS; NEOCLASSICAL TRANSPORT THEORY; NONLINEAR PROBLEMS; OSCILLATIONS; PLASMA CONFINEMENT; PLASMA SIMULATION; PLASMA WAVES; REVERSED SHEAR; SPHERICAL CONFIGURATION; TEARING INSTABILITY