First observation of unlocking the locked mode by electrode biasing on J-TEXT tokamak. (21st December 2020)

• Record Type: Journal Article
• Authors: Chen, Zhipeng; Wang, Tong; Yu, Qingquan; Hu, Qiming; Li, Da; Yang, Jie; Han, Dongliang; Shen, Chengshuo; Xia, Minghui; Liu, Hai; Wang, Nengchao; Huang, Zhuo; Yang, Zhoujun; Cheng, Zhifeng; Gao, Li; Ding, Yonghua; Shi, Peng; Chen, Zhongyong; Zhuang, Ge; Liang, Yunfeng; team, J-TEXT
• Is Part Of: Nuclear fusion. Volume 61:Number 2(2021)
• Publication Date: 2020-12-21
• Subjects: tearing mode -- locked mode unlocking -- electrode biasing -- disruption avoidance; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/abc1f6
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: Major disruptions, often caused by locked m / n = 2/1 modes ( m / n is the poloidal/toroidal mode number), are great threat to a tokamak fusion reactor and should be mitigated or avoided. The locked 2/1 modes have been unlocked by electrode biasing (EB) for the first time in J-TEXT tokamak experiments. The application of a sufficiently negative EB voltage in plasma edge region quickly changes the phase and amplitude of the locked 2/1 mode and drives the mode to rotate in about 10–30 ms. For a larger EB current or a smaller locked mode amplitude, the mode is more easily to be unlocked, revealing a new method for mode unlocking and avoiding plasma disruptions.