Multi-scale interaction of pedestal instabilities in H-mode plasma on the EAST tokamak. (10th April 2019)

• Record Type: Journal Article
• Authors: Zhang, T.; Geng, K.N.; Liu, H.Q.; Liu, Y.; Shi, T.H.; Duan, Y.M.; Liu, J.B.; Xiang, H.M.; Wang, Y.M.; Wen, F.; Li, G.S.; Ye, K.X.; Wu, M.F.; Huang, J.; Zhang, S.B.; Gao, X.
• Other Names: collab.
• Is Part Of: Nuclear fusion. Volume 59:Number 5(2019:May)
• Publication Date: 2019-04-10
• Subjects: cross-scale interaction -- pedestal instabilities -- H-mode; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/ab0755
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: A cross-scale interaction between a kink instability with toroidal mode number ( n ) of 1 and background microturbulence (mainly a coherent mode with n = 12–17) has been observed in the H-mode edge pedestal region in the EAST tokamak. The n = 1 kink mode with a frequency ~3.5 kHz is localized in the pedestal region. The amplitude of pedestal microturbulence is evidently modulated at the frequency of the n = 1 mode. This amplitude modulation is mainly for the fluctuation component with frequency less than 100 kHz, while no modulation by the n = 1 mode is observed for the component with frequency larger than 100 kHz. This implies that the observed amplitude modulation by the n = 1 mode is not due to the Doppler shift effect. A further analysis shows that the amplitude modulation of microturbulence could be attributed to modulation of the local temperature gradient by the n = 1 kink mode. In addition, bicoherence analysis indicates that there exists a possible direct nonlinear interaction between background microturbulence and the n = 1 kink instability. A preliminary analysis shows that this cross-scale interaction has no evident effect on the pedestal structure.