Global gyrokinetic simulations find that realistic density gradients of energetic particles can simultaneously excite low frequency Alfven eigenmodes in toroidal geometry, beta-induced Alfven-acoustic eigenmode (BAAE) and beta-induced Alfven eigenmode (BAE), with similar radial mode widths and comparable linear growth rates even though damping rate of BAAE is much larger than BAE in the absence of energetic particles. This surprising result is attributed to non-perturbative effects of energetic particles that modify ideal BAAE mode polarizations and nonlocal geometry effects that invalidate radially local dispersion relation. Dominant mode changes from BAAE in a larger tokamak to BAE in a smaller tokamak due to the dependence of wave-particle resonance condition on the tokamak size.
全球回旋动力学模拟发现，在环形几何中，高能粒子的真实密度梯度能够同时激发低频阿尔芬本征模，即β诱导阿尔芬-声学本征模（BAAE）和β诱导阿尔芬本征模（BAE），二者具有相似的径向模宽度和相当的线性增长率，尽管在不存在高能粒子时BAAE的阻尼率远大于BAE。这一令人惊讶的结果归因于高能粒子的非微扰效应，该效应修正了理想BAAE的模偏振，以及非局域几何效应，该效应使得径向局域色散关系不再成立。由于波-粒子共振条件对托卡马克尺寸的依赖性，主导模从较大托卡马克中的BAAE转变为较小托卡马克中的BAE。