期刊
NUCLEAR FUSION
卷 57, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0029-5515/57/1/016034
关键词
NSTX; fishbone; frequency chirping; nonlinear dynamics; wave-particle interaction
资金
- Department of Energy Scientific Discovery through Advanced Computing (SciDAC) [DE-AC02-09CH11466]
- National Natural Science Foundation of China [11505022]
- China Postdoctoral Science Foundation [2014M561218]
- CASHIPS [YZJJ201510]
Linear and nonlinear kinetic-MHD hybrid simulations have been carried out to investigate linear stability and nonlinear dynamics of beam-driven fishbone instability in spherical tokamak plasmas. Realistic NSTX parameters with finite toroidal rotation were used. The results show that the fishbone is driven by both trapped and passing particles. The instability drive of passing particles is comparable to that of trapped particles in the linear regime. The effects of rotation are destabilizing and a new region of instability appears at higher qmin (> 1.5) values, q(min) being the minimum of safety factor profile. In the nonlinear regime, the mode saturates due to flattening of beam ion distribution, and this persists after initial saturation while mode frequency chirps down in such a way that the resonant trapped particles move out radially and keep in resonance with the mode. Correspondingly, the flattening region of beam ion distribution expands radially outward. A substantial fraction of initially non-resonant trapped particles become resonant around the time of mode saturation and keep in resonance with the mode as frequency chirps down. On the other hand, the fraction of resonant passing particles is significantly smaller than that of trapped particles. Our analysis shows that trapped particles provide the main drive to the mode in the nonlinear regime.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据