Localization of the eigenmode of the drift-resistive plasma by zonal flow

2018 ◽  
Vol 25 (10) ◽  
pp. 102501 ◽  
Author(s):  
Chang-Bae Kim ◽  
Byunghoon Min ◽  
Chan-Yong An
Keyword(s):  
Zonal Flow ◽  
Resistive Plasma

Suppression of turbulence in the drift-resistive plasma where zonal flow changes direction

2020 ◽  
Vol 86 (3) ◽  
Author(s):  
Chang-Bae Kim
Keyword(s):  
Electric Potential ◽  
Zonal Flow ◽  
Equilibrium Density ◽  
Turbulence Level ◽  
Edge Region ◽  
Transport Barrier ◽  
Large Gradient ◽  
Resistive Plasma ◽  
Flow Changes

The edge region of quasi-adiabatic plasma is pedagogically simulated by the dynamics between the electric potential $\unicode[STIX]{x1D711}$ and the electron density $n$ whose equilibrium density gradient is negative and held fixed. The zonal flow (ZF) $V$ is either enforced sinusoidally or generated self-consistently from the turbulence. Cross-phase $\unicode[STIX]{x1D6FF}$ between $\unicode[STIX]{x1D711}$ and $n$ , which is important in the determination of the turbulence level and the transport, is strongly influenced by the ZF. In the region near $V=0$ , $\unicode[STIX]{x1D6FF}$ becomes negative due to the large gradient of the ZF. It is found that the instabilities are quenched there, and the fluctuations decay. The ZF thus works as a transport barrier in the region where the ZF changes direction with large gradient.

scholarly journals Low-cost Solutions for Velocimetry in Rotating and Opaque Fluid Experiments using Ultrasonic Time of Flight

2021 ◽  
Author(s):  
Fabian Burmann ◽  
Jerome Noir ◽  
Stefan Beetschen ◽  
Andrew Jackson
Keyword(s):  
Acoustic Waves ◽  
Flow Measurement ◽  
Low Cost ◽  
Time Of Flight ◽  
Zonal Flow ◽  
Gravitational Acceleration ◽  
Complex Flow ◽  
Ultrasonic Time ◽  
Theoretical Predictions ◽  
Complex Flow Structure

AbstractMany common techniques for flow measurement, such as Particle Image Velocimetry (PIV) or Ultrasonic Doppler Velocimetry (UDV), rely on the presence of reflectors in the fluid. These methods fail to operate when e.g centrifugal or gravitational acceleration leads to a rarefaction of scatterers in the fluid, as for instance in rapidly rotating experiments. In this article we present two low-cost implementations for flow measurement based on the transit time (or Time of Flight) of acoustic waves, that do not require the presence of scatterers in the fluid. We compare our two implementations against UDV in a well controlled experiment with a simple oscillating flow and show we can achieve measurements in the sub-centimeter per second velocity range with an accuracy of $\sim 5-10\%$ ∼ 5 − 10 % . We also perform measurements in a rotating experiment with a complex flow structure from which we extract the mean zonal flow, which is in good agreement with theoretical predictions.

scholarly journals Wave-kinetic approach to zonal-flow dynamics: Recent advances

2021 ◽  
Vol 28 (3) ◽  
pp. 032303
Author(s):  
Hongxuan Zhu ◽  
I. Y. Dodin
Keyword(s):  
Zonal Flow ◽  
Flow Dynamics ◽  
Kinetic Approach ◽  
Recent Advances

scholarly journals Vortex–Vortex Interactions for the Maintenance of Blocking. Part II: Numerical Experiments

2013 ◽  
Vol 70 (3) ◽  
pp. 743-766 ◽  
Author(s):  
Akira Yamazaki ◽  
Hisanori Itoh
Keyword(s):  
Numerical Experiments ◽  
Channel Model ◽  
Spherical Model ◽  
Zonal Flow ◽  
Selective Absorption ◽  
Absorption Mechanism ◽  
Vortex Interactions ◽  
Maintenance Mechanism ◽  
Uniform Background

Abstract The selective absorption mechanism (SAM), newly proposed in Part I of this study on the maintenance mechanism of blocking, is verified through numerical experiments. The experiments were based on the nonlinear equivalent-barotropic potential vorticity equation, with varying conditions with respect to the shape and amplitude of blocking, and characteristics of storm tracks (displacement and strength) and background zonal flow. The experiments indicate that the SAM effectively maintains blocking, irrespective of the above conditions. At first, by applying a channel model on a β plane, numerical experiments were conducted using a uniform background westerly with and without a jet. The results show that the presence of a jet promotes the effectiveness of the SAM. Then, two types of spherical model experiments were also performed. In idealized experiments, the SAM was as effective as the β-plane model in explaining the maintenance of blocking. Moreover, experiments performed under realistic meteorological conditions showed that the SAM maintained a real block, demonstrating that the SAM is effective. These results, and the case study in Part I, verify that the SAM is the effective general maintenance mechanism for blocking.

scholarly journals Erratum: “Zonal flow in a tokamak pedestal” [Phys. Plasmas 16, 056105 (2009)]

2009 ◽  
Vol 16 (9) ◽  
pp. 099902 ◽  
Author(s):  
Grigory Kagan ◽  
Peter J. Catto
Keyword(s):  
Zonal Flow
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