Techniques developed in the domain of optical theory are applied to investigate the behavior of Geodesic Acoustic Modes (GAMs). In this context, we show that this approach represents a powerful basis for the description of many characteristics of radial propagation and spreading of GAMs. The most attractive feature of these techniques is represented by their universality and intuitive applicability. We present and apply two different complex-eikonal methods able to describe the spreading of GAMs in terms of local plane waves. The methods are “inhomogeneous wave tracking” and “paraxial WKB” theory. We demonstrate their applicability and efficacy to the GAM dynamics problem by means of a comparison with gyrokinetic simulations.

中文翻译：

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应用于测地线声模动力学的复杂特征方法

在光学理论领域开发的技术被应用于研究测地声学模式 (GAM) 的行为。在这种情况下，我们表明这种方法代表了描述 GAM 径向传播和传播的许多特征的强大基础。这些技术最吸引人的特点是它们的普遍性和直观的适用性。我们提出并应用了两种不同的复本征方法，能够根据局部平面波来描述 GAM 的传播。方法是“非均匀波跟踪”和“近轴WKB”理论。我们通过与陀螺动力学模拟的比较来证明它们对 GAM 动力学问题的适用性和有效性。