Exciting and propagating characteristics of two coexisting kinetic geodesic acoustic modes in the edge of plasma

Nuclear Fushion

article

D.F. Kong¹  A.D. Liu²  T. Lan²  C.X. Yu²  J. Cheng³  Z.Y. Qiu⁴  H.L. Zhao¹  H.G. Shen²  L.W. Yan³  J.Q. Dong³  M. Xu³  K.J. Zhao³  X.R. Duan³  Y. Liu³  R. Chen¹  S.B. Zhang¹  X. Sun²  J.L. Xie²  H. Li²  W.D. Liu² 

[1] Institute of Plasma Physics, Chinese Academy of Sciences;Department of Modern Physics, University of Science and Technology of China;Southwestern Institute of Physics;Institute for Fusion Theory and Simulation, Zhejiang University

关键词: zonal flow;    kinetic GAM;    ambient turbulence;   

DOI  :  10.1088/1741-4326/aa5c62

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

Coexisting dual kinetic geodesic acoustic modes (KGAMs) with similar characteristics have been observed with Langmuir probe arrays in the edge plasma of HL-2A tokamak with low density Ohmic discharge. The dual KGAMs are named a low-frequency GAM (LFGAM) and a high-frequency GAM (HFGAM), respectively. By changing the line averaged density from 1.0imes {{10}^{19}}~{{ext{m}}^{-3}}to 0.7imes {{10}^{19}}~{{ext{m}}^{-3}} , the study ofn _e andT _e profiles indicate that collision damping rate plays a crucial role on exciting of dual KGAMs, especially for the higher frequency branch (HFGAM). With the application of modulating techniques, we provide direct proof that nonlinear interactions between GAMs and ambient turbulence (AT) show great difference at different radial positions. At the exciting position of GAM, the amplitude modulation of AT is dominant, indicating that GAM is generated in the energy-conserving triad interaction. After the exciting of GAMs, they will propagate both inward and outward. During the propagation, the phase modulation of AT is dominant, GAMs can rarely gain energy from AT, yet they can give back-reactions on AT through shearing effect.

【 授权许可】

Unknown