Experimental identification of nonlinear coupling between (intermediate, small)-scale microturbulence and an MHD mode in the core of a superconducting tokamak. (1st November 2017)

• Record Type: Journal Article
• Authors: Sun, P.J.; Li, Y.D.; Ren, Y.; Zhang, X.D.; Wu, G.J.; Xu, L.Q.; Chen, R.; Li, Q.; Zhao, H.L.; Zhang, J.Z.; Shi, T.H.; Wang, Y.M.; Lyu, B.; Hu, L.Q.; Li, J.
• Other Names: collab.
• Is Part Of: Nuclear fusion. Volume 58:Number 1(2018:Jan.)
• Publication Date: 2017-11-01
• Subjects: nonlinear coupling -- multi-scale -- density fluctuation -- microturbulence; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/aa8a91
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: In this paper, we present clear experimental evidence of core region nonlinear coupling between (intermediate, small)-scale microturbulence and an magnetohydrodynamics (MHD) mode during the current ramp-down phase in a set of L-mode plasma discharges in the experimental advanced superconducting tokamak (EAST, Wan et al (2006 Plasma Sci. Technol .8 253)). Density fluctuations of broadband microturbulence ( k ⊥ ρ i ∼ 2 − 5.2 ) and the MHD mode (toroidal mode number m = − 1, poloidal mode number n = 1 ) are measured simultaneously, using a four-channel tangential C O 2 laser collective scattering diagnostic in core plasmas. The nonlinear coupling between the broadband microturbulence and the MHD mode is directly demonstrated by showing a statistically significant bicoherence and modulation of turbulent density fluctuation amplitude by the MHD mode.