The q-profile effect on high-order harmonic q = 1 tearing mode generation during sawtooth crashes

Journal Article · Fri Jun 15 04:00:00 EDT 2012 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4731720· OSTI ID:22072447

Zhengxiong, Wang; Lai, Wei ^[1]; Xiaogang, Wang ^[2]

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1. MOE Key Laboratory of Materials Modification by Beams, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)
2. State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China)

The effect of q-profiles on the excitation of high-order harmonic q=1 tearing modes during sawtooth crashes is investigated by a collisionless fluid model with the electron inertia term in Ohm's law. It is found that for a flat q-profile in the core region, the high-order harmonics, such as m/n=2/2 and/or m/n=3/3 modes, comparable to or stronger than the m/n=1/1 component, can be excited during tokamak sawteeth. The stronger the magnetic shear on the q=1 surface is, the more unstable the higher-m modes are. For smoothly monotonously increased q-profiles, a lower q value on the plasma edge tends to easily excite higher-m harmonics at the same level as the m = 1 mode simultaneously. The spatial characteristics of the eigenmodes in the cases with the typical q-profiles are also discussed. In addition, the basic feature of the magnetic island structures in the nonlinear evolution is numerically obtained, which is consistent qualitatively with the experimentally reconstructed phenomenon.

• OSTI ID: 22072447
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 6 Vol. 19; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ELECTRONS
EXCITATION
HARMONICS
MAGNETIC ISLANDS
NONLINEAR PROBLEMS
OHM LAW
PLASMA
Q-VALUE
SAWTOOTH OSCILLATIONS
TEARING INSTABILITY
TOKAMAK DEVICES