Excitation of RSAEs during Sawteeth-Like Oscillation in EAST
Ming Xu1, Guoqiang Zhong1*, Baolong Hao2, Wei Shen1, Liqun Hu1, Wei Chen3, Zhiyong Qiu4, Xuexi Zhang1, Youjun Hu1, Yingying Li1,5,6, Hailin Zhao1, Haiqing Liu1, Bo Lyu1, and the EAST Team1
1Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP), Hefei 230031, China 2Advanced Energy Research Center, Shenzhen University, Shenzhen 518060, China 3Southwestern Institute of Physics, Chengdu 610041, China 4Department of Physics, Zhejiang University, Hangzhou 310027, China 5Enn Science and Technology Development Co., Ltd, Langfang 065001, China 6Hebei Key Laboratory of Compact Fusion, Langfang 065001, China
Abstract：The excitation condition of reversed shear Alfvén eigenmodes (RSAEs) has been investigated during sawtooth-like oscillation in the EAST tokamak. The sawtooth-like phenomena can be reproduced in the configuration of reversed magnetic shear, and the threshold gradient of electron temperature is formed accordingly, together with the increasing of the confinement of thermal particles. The distribution function of energetic ions density is altered dramatically when the neutral beam is switched from NBI1L (tangent) to NBI1R (perpendicular), which can be captured by the measurement of radial neutron camera. The RSAEs are excited easily in the vicinity of $q_{\min}$ (1.99 m $\leq R \leq 2.06$ m) for the injection of neutral beam with perpendicular direction, which should be excited by the steep gradient of energetic ions density. Furthermore, the excitation of RSAEs and the formation of threshold gradient of electron temperature can take place concurrently, which means that the neutral beam with perpendicular injection is beneficial for the establishment of internal transport barrier.
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2021, Vol. 38 
