Experimental observation of reverse- sheared Alfvén eigenmodes (RSAEs) in ELMy H-mode plasma on the EAST tokamak

Tao ZHANG (张涛); Haiqing LIU (刘海庆); Guoqiang LI (李国强); Long ZENG (曾龙); Yao YANG (杨曜); Tingfeng MING (明廷凤); Xiang GAO (高翔); Hui LIAN (连辉); Kai LI (李凯); Yong LIU (刘永); Yingying LI (李颖颖); Tonghui SHI (石同辉); Xiang HAN (韩翔); the EAST team

doi:10.1088/2058-6272/aac9b5

Plasma Science and Technology > 2018 > 20(11): 115101. > DOI: 10.1088/2058-6272/aac9b5

Tao ZHANG (张涛), Haiqing LIU (刘海庆), Guoqiang LI (李国强), Long ZENG (曾龙), Yao YANG (杨曜), Tingfeng MING (明廷凤), Xiang GAO (高翔), Hui LIAN (连辉), Kai LI (李凯), Yong LIU (刘永), Yingying LI (李颖颖), Tonghui SHI (石同辉), Xiang HAN (韩翔), the EAST team. Experimental observation of reverse- sheared Alfvén eigenmodes (RSAEs) in ELMy H-mode plasma on the EAST tokamak[J]. Plasma Science and Technology, 2018, 20(11): 115101. DOI: 10.1088/2058-6272/aac9b5

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Experimental observation of reverse- sheared Alfvén eigenmodes (RSAEs) in ELMy H-mode plasma on the EAST tokamak

¹ Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People’s Republic of China
² University of Science and Technology of China, Hefei 230026, People’s Republic of China

Funds: This work has been supported by the National Key R&D Program of China (No. 2014GB106004) and National Natural Science Foundation of China (Nos. 11605235, 11675211, 11505221) and Scientific Research Grant of Hefei Science Center of CAS (No. 2015SRG-HSC010).

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Received Date: March 12, 2018

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Abstract

Abstract

Reverse-sheared Alfvén eigenmodes (RSAEs) have been observed by using an interferometer and ECE diagnostics in NBI heated ELMy H-mode plasma on EAST tokamak. A typical feature of these modes is a fast frequency sweeping upward from ∼80 kHz to ∼110 kHz in hundred milliseconds during which the plasma temperature, density and rotation keeps no change. Only core channels of the interferometer can observe these modes, implying a core localized mode. The ECE measurement further showed that these modes located at about ρ=0.37–0.46, just around the position of q_min with ρ∼0.4. These core localized modes are very weak in the magnetic fluctuations measured by mirnov probes mounted at the machine vacuum vessel. A multiple frequency fluctuation component, seemingly the so-called ‘grand cascades’, was also clearly observed on the ECE signal at ρ=0.46. During the phase, a transient internal transport barrier (ITB) in ion temperature and toroidal rotation was observed and the ITB foot was just close to the position of q_min . A modulation of RSAE frequency by ELM event was observed and this modulation could be attributed to rotation decrease or q_minincrease due to ELM. Further study of these modes in EAST can provide valuable constraints for the q profile measurement and will be important for the long pulse operation.
- reverse-sheared Alfvén eigenmodes,
- ITB,
- q profile

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References (39)

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