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Kinetic-MHD hybrid simulation of fishbone modes excited by fast ions on the experimental advanced superconducting tokamak (EAST)

Authors :
Youbin Pei
Nong Xiang
Yasushi Todo
Guoqiang Li
Wei Shen
Youjun Hu
Liqing Xu
Source :
Physics of Plasmas 24, 032507 (2017); https://doi.org/10.1063/1.4978562
Publication Year :
2017
Publisher :
AIP Publishing, 2017.

Abstract

Kinetic-MagnetoHydroDynamic hybrid simulations are carried out to investigate fishbone modes excited by fast ions on the Experimental Advanced Superconducting Tokamak. The simulations use realistic equilibrium reconstructed from experiment data with the constraint of the q = 1 surface location (q is the safety factor). Anisotropic slowing down distribution is used to model the distribution of the fast ions from neutral beam injection. The resonance condition is used to identify the interaction between the fishbone mode and the fast ions, which shows that the fishbone mode is simultaneously in resonance with the bounce motion of the trapped particles and the transit motion of the passing particles. Both the passing and trapped particles are important in destabilizing the fishbone mode. The simulations show that the mode frequency chirps down as the mode reaches the nonlinear stage, during which there is a substantial flattening of the perpendicular pressure of fast ions, compared with that of the parallel pressure. For passing particles, the resonance remains within the q = 1 surface, while, for trapped particles, the resonant location moves out radially during the nonlinear evolution. In addition, parameter scanning is performed to examine the dependence of the linear frequency and growth rate of fishbones on the pressure and injection velocity of fast ions.

Details

Language :
English
ISSN :
1070664X
Volume :
24
Issue :
3
Database :
OpenAIRE
Journal :
Physics of Plasmas
Accession number :
edsair.doi.dedup.....8907cc3401bd3e2d1576cdaec3aa61be
Full Text :
https://doi.org/10.1063/1.4978562