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Indexed by:期刊论文

Date of Publication:2012-06-01

Journal:PHYSICS OF PLASMAS

Included Journals:SCIE、EI

Volume:19

Issue:6

ISSN No.:1070-664X

Abstract: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. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4731720]