Mode structure symmetry breaking of reversed shear Alfvén eigenmodes and its impact on the generation of parallel velocity asymmetries in energetic particle distribution

• 作者: Guo MENG Philipp LAUBER Xin WANG Zhixin LU
• 来源期刊: 等离子体科学和技术（英文版）
• 年，卷（期）: 2022,（2）
• 所属期刊栏目: MAGNETICALLY CONFINED PLASMA
• 页码范围: 17-27
• 页数: 11页
• 语种: 英文

摘要

In this work,the gyrokinetic eigenvalue code LIGKA,the drift-kinetic/MHD hybrid code HMGC and the gyrokinetic full-fcode TRIMEG-GKX are employed to study the mode structure details of reversed shear Alfvén eigenmodes(RSAEs).Using the parameters from an ASDEX-Upgrade plasma,a benchmark with the three different physical models for RSAE without and with energetic particles(EPs)is carried out.Reasonable agreement has been found for the mode frequency and the growth rate.Mode structure symmetry breaking(MSSB)is observed when EPs are included,due to the EPs'non-perturbative effects.It is found that the MSSB properties are featured by a finite radial wave phase velocity,and the linear mode structure can be well described by an analytical complex Gaussian expression Φ(s)=e-σ(s-s0)2 with complex parameters σ and s0,where s is the normalized radial coordinate.The mode structure is distorted in opposite manners when the EP drive shifted from one side of qmin to the other side,and specifically,a non-zero average radial wave number<ks>with opposite signs is generated.The initial EP density profiles and the corresponding mode structures have been used as the input of HAGIS code to study the EP transport.The parallel velocity of EPs is generated in opposite directions,due to different values of the average radial wave number<ks>,corresponding to different initial EP density profiles with EP drive shifted away from the qmin.