Jul 2 – 6, 2018
Žofín Palace
Europe/Prague timezone

P2.1081 Turbulence Regulation with Radial Wavenumber Spectral Shift Caused by LHCD Induced Velocity Shear during ELM Mitigation

Jul 3, 2018, 2:00 PM
2h
Mánes

Mánes

Speaker

Xiaolan Zou

Description

See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P2.1081.pdf Turbulence Regulation with Radial Wavenumber Spectral Shift Caused by LHCD Induced Velocity Shear during ELM Mitigation X.L. Zou1, G.L. Xiao2,3, W.L. Zhong2, S.D. Song2, X.R. Duan2, A.D. Liu4, X.Y. Bai2, J. Cheng2, Z.Y. Cui2, L. Delpech1, X.T. Ding2, J.Q. Dong2,5, A. Ekedahl1, B.B. Feng2, G. Giruzzi1, J.M. Gao2, M. Goniche1, G.T. Hoang1, X.Q. Ji2, M. Jiang2, B. Lu2, D. Mazon1, Y. Peysson1, X.M. Song2, Z.B. Shi2, M. Xu2, D.L.Yu2, B.Y. Zhang2, Y.P. Zhang2, Y. Zhou2 and HL-2A team2 1 CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France 2 Southwestern Institute of Physics, P.O. Box 432, Chengdu, China 3 Department of Engineering physics, Tsinghua University, Beijing, China 4 KTX Laboratory and Department of Modern Physics, University of Science and Technology of China, Anhui Hefei 230026,China 5 Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou, China Email: xiao-lan.zou@cea.fr ELM mitigation with LHCD has been achieved in the HL-2A tokamak for high plasma density (ne ≥ 2.5×1019 m-3) and large LHCD absorbed power (PLHCD ≥ 300 kW) [1]. The divertor peak heat load induced by ELM has been significantly reduced during the mitigation phase. A severe decrease of the pedestal velocity shear has been observed with LHCD switch on, while the kr-spectrum of the pedestal turbulence is shifted toward the origin (Fig.1(d)). It has been found that the ELM mitigation is desynchronized with LHCD pulse, but it is closely correlated to the pedestal turbulence enhancement (Fig.1(e)). In order to understand the mechanism of the turbulence enhancement during ELM mitigation, a theoretical model, based on the regulation of the turbulence amplitude by its radial wavenumber spectral shift caused by external velocity shear, has been developed. A critical growth rate for the turbulence regulation has been identified in this model. It has been found that the turbulence enhancement and ELM mitigation occur Fig.1 ELM mitigation with LHCD. when the decrease of LHCD driven velocity shear exceeds a threshold value, which directly depends on . Good agreement has been found between experiment and theory for the regulation of the turbulence amplitude with its averaged radial wavenumber. Reference [1] G.L. Xiao et al., Phys. Plasmas 24 (2017) 122507

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