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See full abstract here
http://ocs.ciemat.es/EPS2019ABS/pdf/P2.1022.pdf
Edge coherent mode (ECM), previously identified as the dissipative trapped electron mode [1], is commonly observed in the H-mode pedestal with a relative high collisionality in the EAST tokamak. This mode is considered contributing significantly to suppression of crash of large ELMs benefitting from the remarkable particle and heat exhaust induced by the mode. Recently, when ELMs are suppressed by applying a slowly rotating resonant magnetic fields perturbations (RMPs) in the toroidal direction with a dominant n=1 component, both amplitude and spectral width of ECM are observed periodically with the rotation of RMP.
In this experiment, plasma stored energy and global density change less than 5% during application of 3D fields. Local measurements of radial electric field Er, plasma density and electron temperature in the pedestal are modulated by 3D fields. Pedestal moves outward with the increasing of local fluctuation intensity and bandwidth. Broadband ECM is presented and its fluctuation amplitude varies in phase by 100% or more. The enhanced fluctuation level is accompanied by a decreasing in pedestal pressure gradient by 8%. Meanwhile, poloidal velocity spins up in the ion-diamagnetic-drift direction slightly and induces a decrease in shearing rate by 27%. During the pedestal and ECM moving inward phase, ECM fluctuation amplitude decreases by 50% while the radial pedestal pressure increases by 6% and shearing rate increases by 30% in the same zone. The decrease in fluctuation amplitude is synchronous with a decrease of spectra width. The tilted ECM eddy is also observed by ECEI before ECM nearly disappear. These dynamical behaviors suggest that non-axisymmetric edge fluctuation is attributed to radial movement of electric potential in the plasma which is induced by RMP field.
[1] H.Q. Wang and G.S. Xu, et al, Phys. Rev. Lett. 112 185004 (2014)
