Global simulations of energetic electron excitation of beta-induced Alfven eigenmodes
Global simulations of energetic electron excitation of beta-induced Alfven eigenmodes
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DOI：
10.7498/aps.72.20230794
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发表时间：
2023
影响因子：
1
通讯作者：
Bao Jian;Zhang Wenlu;Li Ding
中科院分区：
文献类型：
--
作者：
Bao Jian;Zhang Wenlu;Li Ding
采用基于朗道流体体等离子体和漂移动力学电子激发的混合模型，利用新开发的全局本征值程序MAS，研究了高能电子对β-诱导Alfven本征模的激发，特别是考虑了有限Larmor半径、抗磁漂移和朗道阻尼等体动力学效应，并考虑了对流的绝热流体响应和进动漂移共振的非绝热动力学响应。非微扰求解了托卡马克中e-BAE模式结构和线性色散关系的整体本征模方程。e-BAE模结构的径向宽度随着环形模数的增加而变窄，这可以用Alfven连续谱的变化来解释，Alfven连续谱与动力学Alfven波相互作用形成相应的本征模。对于进动漂移共振失稳，e-BAE增长率随环模数呈现非单调变化，而e-BAE的真实的频率接近连续谱积累点，且几乎保持不变.通过MAS非微扰模拟分析了电子束密度和温度对电子束稳定性的影响，结果表明，电子束密度可以影响电子束的真实的频率，从而改变共振条件，导致电子束在强电子束驱动下的稳定性.此外，还报道了EE非微扰对e-BAE模结构对称性破缺的影响。极向对称性破缺的“回旋镖”形的2D结构的特点，可以大大增强EE温度的提高，连同大的径向变化的主导主极向谐波的极向相位角。当EE密度/温度驱动相对于相应的有理曲面不对称时，e-BAE模结构的径向对称性破缺会出现，这会导致e-BAE平行波数的净体积平均值驱动等离子体的内禀旋转。这些结果有助于理解在最近的实验中观察到的e-BAE动力学。
The energetic electron (EE) excitation of beta-induced Alfven eigenmodes are investigated using the newly developed global eigenvalue code MAS, which is based on a hybrid model that consists of Landau fluid bulk plasma and drift kinetic EE. Specifically, the bulk plasma kinetic effects such as finite Larmor radius, diamagnetic drifts and Landau dampings, and the EE adiabatic fluid response of convection and non-adiabatic kinetic response of precessional drift resonance are incorporated in the simulations. The global eigenmode equation is solved for e-BAE mode structure and linear dispersion relation in tokamak non-perturbatively. The radial width of e-BAE mode structure becomes narrower as the toroidal mode number increases, which can be explained by the change of Alfven continuous spectra that interact with kinetic Alfven waves for corresponding eigenmode formation. The e-BAE growth rate exhibits a non-monotonic variation with toroidal mode number for precessional drift resonance destabilization, while the e-BAE real frequency is close to the continuum accumulation point that almost remains the same. The parametric dependences of e-BAE stability on EE density and temperature are analyzed by MAS non-perturbative simulations, which show that the EE density can affect e-BAE real frequency and thus alters the resonance condition, resulting in e-BAE stabilization in the strong EE drive regime. Further, the EE non-perturbative effects on the symmetry breaking of e-BAE mode structure are reported. The poloidal symmetry breaking characterized by the 'boomerang' shape 2D structure can be greatly enhanced by increasing EE temperature, together with the large radial variation of the poloidal phase angle of dominant principal poloidal harmonic. The radial symmetry breaking of e-BAE mode structure arises when EE density/temperature drive is not symmetric with respect to corresponding rational surface, which can lead to a net volume-averaged value of e-BAE parallel wave number that drives plasma intrinsic rotation. These results are helpful for understanding the e-BAE dynamics observed in recent experiments.