The magneto-hydrodynamics (MHD) modes existing in conducting plasmas can greatly affect charged particle’s dynamics. Low frequency MHD perturbations, called the neo-classical tearing (NTM) modes, give rise to magnetic islands which can deteriorate fast ion confinement, especially in tokamak plasmas. Here, a Hamiltonian guiding-center code, based on symplectic algorithm which allows efficient computations of energetic ion trajectories and transport coefficients, has been applied to magnetically perturbed tokamak plasmas. The effects of NTM perturbations on the energetic ion trajectories and diffusion coefficient have been presented. It is demonstrated that the inclusion of such steady state magnetic perturbations in the guiding center drift orbit computations escalates the loss of energetic ions via radial diffusion. Moreover, the broader NTMs lead to a significant enhancement of the radial diffusion coefficient.

中文翻译：

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MHD微扰托卡马克中快离子轨迹和径向扩散系数的辛计算

导电等离子体中存在的磁流体动力学 (MHD) 模式可以极大地影响带电粒子的动力学。低频 MHD 扰动，称为新经典撕裂 (NTM) 模式，会产生磁岛，这会破坏快速离子约束，尤其是在托卡马克等离子体中。在这里，基于辛算法的哈密顿引导中心代码可以有效计算高能离子轨迹和传输系数，已应用于磁扰动托卡马克等离子体。已经介绍了 NTM 扰动对高能离子轨迹和扩散系数的影响。结果表明，在引导中心漂移轨道计算中包含这种稳态磁扰动会增加高能离子通过径向扩散的损失。而且，