Through a systematically developed theory, we demonstrate that the motion of Instanton identified in Zhang et al (2017 Phys. Plasmas 24 122304) is highly correlated to the intermittent excitation and propagation of geodesic acoustic mode (GAM) that is observed in tokamaks. While many numerical simulations have observed the phenomena, it is the first theory that reveals the physical mechanism behind GAM intermittent excitation and propagation. The preceding work is based on the micro-turbulence associated with toroidal ion temperature gradient mode, and slab-based phenomenological model of zonal flow. When full toroidal effect is introduced into the system, two branches of zonal flow emerge: the torus-modified low frequency zonal flow (TLFZF), and GAM, necessitating a unified exploration of GAM and TLFZF. Indeed, we observe that the transition from the Caviton to Instanton is triggered by a rapid zero-crossing of radial group velocity of drift wave and is found to be strongly correlated with the GAM onset. Many features peculiar to intermittent GAMs, observed in real machines, are thus identified in the numerical experiment. The results will be displayed in figures and in a movie; first for single central rational surface, and then with coupled multiple central rational surfaces. The periodic bursting first shown disappears as being replaced by irregular one, more similar to the intermittent characteristics observed in GAM experiments.

通过系统地发展理论，我们证明了瞬的运动张识别等人（2017年物理学。等离子体 24122304）与在托卡马克中观察到的测地线声模（GAM）的间歇激发和传播高度相关。尽管许多数值模拟已经观察到了这种现象，但这是第一个揭示GAM间歇激发和传播背后的物理机制的理论。先前的工作是基于与环形离子温度梯度模式相关的微湍流，以及基于平板的纬向流现象学模型。当将完整的环面效应引入系统中时，出现了两条纬向流分支：经环面修正的低频纬向流（TLFZF）和GAM，因此有必要对GAM和TLFZF进行统一探索。的确，我们观察到从Caviton到Instanton的转变是由漂移波的径向群速度的快速过零触发的，并且发现与GAM的发生密切相关。因此，在数值实验中可以识别出在实际机器中观察到的间歇性GAM特有的许多功能。结果将以数字和电影的形式显示；首先是单个中心有理曲面，然后是耦合的多个中心有理曲面。首先显示的周期性爆发消失为不规则的爆发，与GAM实验中观察到的间歇性特征更相似。首先是单个中心有理曲面，然后是耦合的多个中心有理曲面。首先显示的周期性爆发消失为不规则的爆发，与GAM实验中观察到的间歇性特征更相似。首先是单个中心有理曲面，然后是耦合的多个中心有理曲面。首先显示的周期性爆发消失为不规则的爆发，与GAM实验中观察到的间歇性特征更相似。