Impact of fuelling and impurity on pedestal dynamics and instabilities in the HL-2A tokamak. (3rd November 2016)

• Record Type: Journal Article
• Authors: Zhong, W L; Zou, X L; Gao, J M; Shi, Z B; Feng, B B; Cui, Z Y; Xu, M; Shen, Y; Dong, J Q; Ding, X T; Duan, X R; Liu, Yong
• Other Names: collab.
• Is Part Of: Plasma physics and controlled fusion. Volume 59:Number 1(2017:Jan.)
• Publication Date: 2016-11-03
• Subjects: fuelling -- impurity -- electromagnetic turbulence -- ELM mitigation -- H-mode; Plasma (Ionized gases) -- Periodicals; Controlled fusion -- Periodicals; 530.44
• DOI: 10.1088/0741-3335/59/1/014030
• Languages: English
• ISSNs: 0741-3335

Abstract

Abstract: In recent experiments of the HL-2A tokamak, the effect on the pedestal dynamics by the plasma fuelling with supersonic molecular beam injection (SMBI) has been intensively investigated. Experimental results in several tokamaks suggested that SMBI is a promising technique for ELM mitigation. In addition to the fuelling, the impact of impurities on the pedestal dynamics and instabilities has been investigated in HL-2A. Experimental results have shown that during the H-mode phase, a broadband electromagnetic (EM) turbulence was driven by peaked impurity density profile at the edge plasma region, and governed by double critical gradients of the impurity density. The absolute value of the threshold in positive gradient region is much lower than that in the negative region. This strong asymmetry in the critical gradients has been predicted by theoretical simulation. The results reveal that pedestal dynamics and heat loads can be actively controlled by exciting or changing pedestal instabilities.