Symplectic Simulations of Radial Diffusion of Fast Alpha Particles in the Presence of Low-Frequency Modes in Rippled Tokamaks

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• 作者：Majid Khan ; K. Schoepf ; V. Goloborod’ko ; Zheng-Mao Sheng
• 关键词：Symplectic algorithm ; Toroidal field ripples ; Neoclassical tearing mode ; Radial diffusion coefficient ; Resonance interaction ; Tokamak
• 刊名：Journal of Fusion Energy
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：36
• 期：1
• 页码：40-47
• 全文大小：
• 刊物类别：Engineering
• 刊物主题：Nuclear Fusion; Atoms and Molecules in Strong Fields, Laser Matter Interaction; Nuclear Energy; Sustainable Development; Energy Economics; Renewable and Green Energy;
• 出版者：Springer US
• ISSN：1572-9591
• 卷排序：36

文摘

The symplectic Hamiltonian guiding centre code which enables efficient calculation of charged particle trajectories and diffusion coefficients has been applied to fast ion motion in magnetically perturbed tokamak plasmas. Particularly fusion born alpha particle drift motion, in constant of motion space, is examined in the presence of low mode-number neoclassical tearing mode (NTM) perturbation in a toroidally rippled tokamak. The main focus of this study is to investigate the dependence of the radial diffusion coefficient of energetic ions on the perturbation strength and on the localization of the perturbation. The resonance between bounce motion and toroidal field ripples plays a significant role in this context. The presence of NTMs results in substantial enhancement of radial diffusion coefficient for passing particles. Depending on the strength and localization of the NTM it can cause enhancement or degradation of the radial ripple diffusion coefficient of trapped particles.