Nonlinear simulation of multiple toroidal Alfvén eigenmodes in tokamak plasmas  

作　　者：Xiao-Long Zhu Feng Wang Zheng-Xiong Wang 朱霄龙;王丰;王正汹(Key Laboratory of Materials Modification by Laser,Ion and Electron Beams of the Ministry of Education,School of Physics,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]Key Laboratory of Materials Modification by Laser,Ion and Electron Beams of the Ministry of Education,School of Physics,Dalian University of Technology,Dalian 116024,China

出　　处：《Chinese Physics B》2020年第2期346-355,共10页中国物理B（英文版）

基　　金：Project supported by the National Key R&D Program of China(Grant No.2017YFE0301900);the National Natural Science Foundation of China(Grant No.11675083);the Fundamental Research Funds for the Central Universities of China(Grant No.DUT18ZD101).

摘　　要：Nonlinear evolution of multiple toroidal Alfven eigenmodes(TAEs) driven by fast ions is self-consistently investigated by kinetic simulations in toroidal plasmas.To clearly identify the effect of nonlinear coupling on the beam ion loss,simulations over single-n modes are also carried out and compared with those over multiple-n modes,and the wave-particle resonance and particle trajectory of lost ions in phase space are analyzed in detail.It is found that in the multiple-n case,the resonance overlap occurs so that the fast ion loss level is rather higher than the sum loss level that represents the summation of loss over all single-n modes in the single-n case.Moreover,increasing fast ion beta β_h can not only significantly increase the loss level in the multiple-n case but also significantly increase the loss level increment between the single-n and multiple-n cases.For example,the loss level in the multiple-n case for β_h=6.0% can even reach 13% of the beam ions and is 44% higher than the sum loss level calculated from all individual single-n modes in the single-n case.On the other hand,when the closely spaced resonance overlap occurs in the multiple-n case,the release of mode energy is increased so that the widely spaced resonances can also take place.In addition,phase space characterization is obtained in both single-n and multiple-n cases.Nonlinear evolution of multiple toroidal Alfvén eigenmodes(TAEs)driven by fast ions is self-consistently investigated by kinetic simulations in toroidal plasmas.To clearly identify the effect of nonlinear coupling on the beam ion loss,simulations over single-n modes are also carried out and compared with those over multiple-n modes,and the wave-particle resonance and particle trajectory of lost ions in phase space are analyzed in detail.It is found that in the multiple-n case,the resonance overlap occurs so that the fast ion loss level is rather higher than the sum loss level that represents the summation of loss over all single-n modes in the single-n case.Moreover,increasing fast ion betaβh can not only significantly increase the loss level in the multiple-n case but also significantly increase the loss level increment between the single-n and multiple-n cases.For example,the loss level in the multiple-n case forβh=6.0%can even reach 13%of the beam ions and is 44%higher than the sum loss level calculated from all individual single-n modes in the single-n case.On the other hand,when the closely spaced resonance overlap occurs in the multiple-n case,the release of mode energy is increased so that the widely spaced resonances can also take place.In addition,phase space characterization is obtained in both single-n and multiple-n cases.

关 键 词：TOKAMAK toroidal Alfve′n eigenmode wave-particle interaction beam ion loss 

分 类 号：O53[理学—等离子体物理]