Direct measurement of zonal flows and geodesic acoustic mode oscillations in ASDEX Upgrade using Doppler reflectometry
Direct measurement of zonal flows and geodesic acoustic mode oscillations in ASDEX Upgrade using Doppler reflectometry
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DOI：
10.1088/0741-3335/47/8/003
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发表时间：
2005-08-01
影响因子：
2.2
通讯作者：
Kendl, A
中科院分区：
文献类型：
--
作者：
Conway, GD;Scott, B;Kendl, A
纬向流(ZF)及其相关的测地线振荡是湍流产生的有限径向范围的E-rxB-T刚性极向等离子体流。它们是托卡马克禁闭的主要研究对象，因为它们被认为缓和了漂移波湍流，从而导致了边缘传输。然而，ZF(据信由雷诺应力驱动)和测地线声模(GAM)(与极向压力不对称有关)的检测是具有挑战性的，因为它们主要表现为低频(几千赫兹)电势或径向电场E-r波动。本文用一种新的直接测量E-r起伏的多普勒反射技术测量了欧姆、L模和H模ASDEX升级托卡马克放电中的GAM/ZF特性。
Zonal flows (ZFs) and associated geodesic oscillations are turbulence-generated time-varying E-r x B-T rigid poloidal plasma flows with finite radial extent. They are of major interest for tokamak confinement since they are thought to moderate drift-wave turbulence and hence edge transport. However, detection of ZFs (believed to be driven by Reynolds stress) and Geodesic acoustic modes (GAMs) (linked with poloidal pressure asymmetries) is challenging since they appear predominantly as low frequency (few kilohertz) potential or radial electric field E-r fluctuations. Presented here are measurements of GAM/ZF properties in ohmic, L-mode and H-mode ASDEX Upgrade tokamak discharges using a new Doppler reflectometry technique to measure E-r fluctuations directly.