Chirping and Sudden Excitation of Energetic-Particle-Driven Geodesic Acoustic Modes in a Large Helical Device Experiment.
Chirping and Sudden Excitation of Energetic-Particle-Driven Geodesic Acoustic Modes in a Large Helical Device Experiment.
复制标题
DOI：
10.1103/physrevlett.120.175001
复制
发表时间：
2018-04
影响因子：
8.6
通讯作者：
Hao Wang;Y. Todo;T. Ido;Yasuhiro Suzuki
中科院分区：
文献类型：
--
作者：
Hao Wang;Y. Todo;T. Ido;Yasuhiro Suzuki
利用混合模拟程序研究了在大螺旋装置实验中观测到的高能粒子驱动测地声学模（EGAM）。利用真实物理条件和三维平衡的混合模拟，首次再现了主模的频率啁啾和半频次模的突然激发。这两个EGAM的全球空间分布与实验测量是一致的。对于二次模，体压扰动和高能粒子压扰动相互抵消，因此频率低于一次模。结果表明，二次模的激发不依赖于非线性磁流体耦合。次级模式由高能粒子激发，所述高能粒子分别满足初级模式和次级模式的线性和非线性共振条件。
Energetic-particle-driven geodesic acoustic modes (EGAMs) observed in a Large Helical Device experiment are investigated using a hybrid simulation code for energetic particles interacting with a magnetohydrodynamic (MHD) fluid. The frequency chirping of the primary mode and the sudden excitation of the half-frequency secondary mode are reproduced for the first time with the hybrid simulation using the realistic physical condition and the three-dimensional equilibrium. Both EGAMs have global spatial profiles which are consistent with the experimental measurements. For the secondary mode, the bulk pressure perturbation and the energetic particle pressure perturbation cancel each other out, and thus the frequency is lower than the primary mode. It is found that the excitation of the secondary mode does not depend on the nonlinear MHD coupling. The secondary mode is excited by energetic particles that satisfy the linear and nonlinear resonance conditions, respectively, for the primary and secondary modes.