摘要
采用自主开发的本征值程序MAS,基于朗道流体-漂移动理学混合物理模型,针对近期实验上观测到的高能量电子激发比压阿尔芬本征模(e-BAE)开展动理学模拟研究.通过在全域环几何位形下非微扰求解e-BAE色散关系,得到了e-BAE实频率、增长率和模结构随环向模数的变化特征,并发现e-BAE在高能量电子密度-温度参数空间下存在不稳定岛,而在传统微扰理论下则不存在不稳定岛.进一步分析了高能量电子非微扰效应对e-BAE模结构对称性破缺的影响,结果表明:增大高能量电子温度可以引起显著的极向对称性破缺;移动高能量电子密度剖面使其驱动强度关于有理面不对称时,e-BAE模结构产生径向对称性破缺,并且扰动幅度在平行波数谱空间下分布不对称,从而引起等离子体自发旋转.本文研究结果为理解实验上e-BAE的激发与传播特征具有参考意义.
The energetic electron(EE)excitation of beta-induced Alfvén eigenmodes is investigated by 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 Alfvén continuous spectra that interact with kinetic Alfvén 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 dependence of e-BAE stability on EE density and that on temperature are analyzed by MAS non-perturbative simulations,which shows that the EE density can affect e-BAE real frequency and thus changes the resonance condition,resulting in e-BAE stabilization in the strong EE drive regime.Further,the EE non-perturbative effect on the symmetry breaking of e-BAE mode structure is reported.The poloidal symmetry breaking characterized by the‘boomerang’shape two-dimensional(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 which drives plasma intrinsic rotation.These results are helpful in understanding the e-BAE dynamics observed in recent experiments.
作者
包健
张文禄
李定
Bao Jian;Zhang Wen-Lu;Li Ding(Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2023年第21期157-166,共10页
Acta Physica Sinica
基金
国家自然科学基金(批准号:12275351,11905290,11835016)
国家磁约束核聚变能发展研究专项(批准号:2018YFE0304100)资助的课题.
关键词
高能量电子
比压阿尔芬本征模
非微扰效应
对称性破缺
energetic electron
beta-induced Alfvén eigenmode
non-perturbative effect
symmetry breaking
