Identification of core ion cyclotron instabilities on HL-2A tokamak
Linzi Liu, Ruihai Tong, Xiaolan Zou, Haotian Chen, Yang Chen, G.Q. Dong, Guangzhou Hao, X.X. He, Yuxiao Han, Xiaoquan Ji, A.S. Liang, Bo Li, Jiquan Li, Yonggao Li, L. Liu, Zhongbin Shi, Hui-Ling Wei, Fan Xia, Guoliang Xiao, Jiao Yin, D.L. Yu, Boda Yuan, Yiren Zhu, Wulyu Zhong, Min Xu, HL-2A team
Abstract
Abstract Instabilities in multiplies of ion cyclotron frequency range are identified and termed as core ion cyclotron emission (ICE) in recent HL-2A neutral beam injection heated experiments. Characteristics of the core ICE are presented, including frequency dependence and harmonics features. The detected frequencies are found to agree well with the multiplies of the deuterium cyclotron frequency around the magnetic axis. Additionally, the core ICE exhibits a predominantly compressional property. Observations of distinct spectrum features and individual excitation of each harmonic have demonstrated that the core ICE harmonics are independent multiple modes. Notably, the variation of plasma current is a necessary condition for exciting the 4th harmonic ICE individually. The results suggest that the drive mechanism of core ICE varies between the different frequency ranges.