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Title: Dynamics of zonal shear collapse with hydrodynamic electrons

Abstract

This paper introduces a theory for the collapse of the edge zonal shear layer, as observed at the density limit at low β. We investigate the scaling of the transport and mean profiles with the adiabaticity parameter α, with special emphasizes on fluxes relevant to zonal flow (ZF) generation. We show that the adiabaticity parameter characterizes the strength of production of zonal flows and so determines the state of turbulence. A 1D reduced model that self-consistently describes the spatiotemporal evolution of the mean density $$\overline{n}$$, the azimuthal flow $$\overline{v}_{y}$$, and the turbulent potential enstrophy ε=$$\langle$$$$\tilde{n}$$–∇2$$\tilde{\phi}$$)2/2$$\rangle$$—related to fluctuation intensity—is presented. Quasi-linear analysis determines how the particle flux Γn and vorticity flux Π=–χy2vyres scale with α, in both hydrodynamic and adiabatic regimes. As the plasma response passes from adiabatic (α>1) to hydrodynamic (α<1), the particle flux Γn is enhanced and the turbulent viscosity χy increases. However, the residual flux Πres—which drives the flow—drops with α. As a result, the mean vorticity gradient ∇2$$\overline{v}$$yresy—representative of the strength of the shear—also drops. The shear layer then collapses and turbulence is enhanced. The collapse is due to a decrease in ZF production, not an increase in damping. A physical picture for the onset of collapse is presented. The findings of this paper are used to motivate an explanation of the phenomenology of low β density limit evolution. A change from adiabatic (α=k$$^{2}_{z}$$v$$^{2}_{th}$$/(||ω||νei)>1) to hydrodynamic (α<1) electron dynamics is associated with the density limit.

Authors:
 [1];  [2]; ORCiD logo [3]
  1. Univ. of California, San Diego, CA (United States)
  2. Univ. of California, San Diego, CA (United States); Southwestern Inst. of Physics, Chengdu (China)
  3. Center for Astrophysics and Space Sciences, University of California San Diego, La Jolla, California 92093, USA; Department of Physics, University of California, San Diego, California 92093, USA
Publication Date:
Research Org.:
Univ. of California, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1540209
Alternate Identifier(s):
OSTI ID: 1441086
Grant/Contract Number:  
FG02-04ER54738
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 25; Journal Issue: 6; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Hajjar, R. J., Diamond, P. H., and Malkov, M. A. Dynamics of zonal shear collapse with hydrodynamic electrons. United States: N. p., 2018. Web. doi:10.1063/1.5030345.
Hajjar, R. J., Diamond, P. H., & Malkov, M. A. Dynamics of zonal shear collapse with hydrodynamic electrons. United States. https://doi.org/10.1063/1.5030345
Hajjar, R. J., Diamond, P. H., and Malkov, M. A. Fri . "Dynamics of zonal shear collapse with hydrodynamic electrons". United States. https://doi.org/10.1063/1.5030345. https://www.osti.gov/servlets/purl/1540209.
@article{osti_1540209,
title = {Dynamics of zonal shear collapse with hydrodynamic electrons},
author = {Hajjar, R. J. and Diamond, P. H. and Malkov, M. A.},
abstractNote = {This paper introduces a theory for the collapse of the edge zonal shear layer, as observed at the density limit at low β. We investigate the scaling of the transport and mean profiles with the adiabaticity parameter α, with special emphasizes on fluxes relevant to zonal flow (ZF) generation. We show that the adiabaticity parameter characterizes the strength of production of zonal flows and so determines the state of turbulence. A 1D reduced model that self-consistently describes the spatiotemporal evolution of the mean density $\overline{n}$, the azimuthal flow $\overline{v}_{y}$, and the turbulent potential enstrophy ε=$\langle$$\tilde{n}$–∇2$\tilde{\phi}$)2/2$\rangle$—related to fluctuation intensity—is presented. Quasi-linear analysis determines how the particle flux Γn and vorticity flux Π=–χy∇2vy+Πres scale with α, in both hydrodynamic and adiabatic regimes. As the plasma response passes from adiabatic (α>1) to hydrodynamic (α<1), the particle flux Γn is enhanced and the turbulent viscosity χy increases. However, the residual flux Πres—which drives the flow—drops with α. As a result, the mean vorticity gradient ∇2$\overline{v}$y=Πres/χy—representative of the strength of the shear—also drops. The shear layer then collapses and turbulence is enhanced. The collapse is due to a decrease in ZF production, not an increase in damping. A physical picture for the onset of collapse is presented. The findings of this paper are used to motivate an explanation of the phenomenology of low β density limit evolution. A change from adiabatic (α=k$^{2}_{z}$v$^{2}_{th}$/(||ω||νei)>1) to hydrodynamic (α<1) electron dynamics is associated with the density limit.},
doi = {10.1063/1.5030345},
journal = {Physics of Plasmas},
number = 6,
volume = 25,
place = {United States},
year = {Fri Jun 08 00:00:00 EDT 2018},
month = {Fri Jun 08 00:00:00 EDT 2018}
}

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Works referenced in this record:

Edge shear flows and particle transport near the density limit of the HL-2A tokamak
journal, December 2017


Momentum theorems and the structure of atmospheric jets and zonal flows in plasmas
journal, November 2008


Frequency-Resolved Nonlinear Turbulent Energy Transfer into Zonal Flows in Strongly Heated L -Mode Plasmas in the HL-2A Tokamak
journal, June 2012


Long-range correlations and edge transport bifurcation in fusion plasmas
journal, May 2011


An interpretation of fluctuation induced transport derived from electrostatic probe measurements
journal, April 2002


Resistive drift‐wave turbulence
journal, January 1995

  • Camargo, Suzana J.; Biskamp, Dieter; Scott, Bruce D.
  • Physics of Plasmas, Vol. 2, Issue 1
  • DOI: 10.1063/1.871116

Numerical investigation of frequency spectrum in the Hasegawa-Wakatani model
journal, October 2013

  • Kim, Juhyung; Terry, P. W.
  • Physics of Plasmas, Vol. 20, Issue 10
  • DOI: 10.1063/1.4822335

Dynamics of intrinsic axial flows in unsheared, uniform magnetic fields
journal, May 2016

  • Li, J. C.; Diamond, P. H.; Xu, X. Q.
  • Physics of Plasmas, Vol. 23, Issue 5
  • DOI: 10.1063/1.4950830

I-mode: an H-mode energy confinement regime with L-mode particle transport in Alcator C-Mod
journal, August 2010


Density limits in toroidal plasmas
journal, July 2002


Physical Mechanism behind Zonal-Flow Generation in Drift-Wave Turbulence
journal, October 2009


A new look at density limits in tokamaks
journal, December 1988


Plasma Edge Turbulence
journal, February 1983


How mesoscopic staircases condense to macroscopic barriers in confined plasma turbulence
journal, November 2016


Transport matrix for particles and momentum in collisional drift waves turbulence in linear plasma devices
journal, February 2016

  • Ashourvan, Arash; Diamond, P. H.; Gürcan, Ö. D.
  • Physics of Plasmas, Vol. 23, Issue 2
  • DOI: 10.1063/1.4942420

Collisional Scaling of the Energy Transfer in Drift-Wave Zonal Flow Turbulence
journal, January 2017


Zonal flow triggers the L-H transition in the Experimental Advanced Superconducting Tokamak
journal, July 2012

  • Manz, P.; Xu, G. S.; Wan, B. N.
  • Physics of Plasmas, Vol. 19, Issue 7
  • DOI: 10.1063/1.4737612

Energetics of the interaction between electromagnetic ExB turbulence and zonal flows
journal, January 2005


Bifurcation in electrostatic resistive drift wave turbulence
journal, October 2007

  • Numata, Ryusuke; Ball, Rowena; Dewar, Robert L.
  • Physics of Plasmas, Vol. 14, Issue 10
  • DOI: 10.1063/1.2796106

Synergy of Anomalous Transport and Radiation in the Density Limit
journal, August 2003


Drift waves and transport
journal, April 1999


Role of Zonal Flow Predator-Prey Oscillations in Triggering the Transition to H-Mode Confinement
journal, April 2012


Modelling enhanced confinement in drift-wave turbulence
journal, June 2017

  • Hajjar, R. J.; Diamond, P. H.; Ashourvan, A.
  • Physics of Plasmas, Vol. 24, Issue 6
  • DOI: 10.1063/1.4985323

Zonal flow generation and its feedback on turbulence production in drift wave turbulence
journal, April 2013

  • Pushkarev, Andrey V.; Bos, Wouter J. T.; Nazarenko, Sergey V.
  • Physics of Plasmas, Vol. 20, Issue 4
  • DOI: 10.1063/1.4802187

Influence of sheared poloidal rotation on edge turbulence
journal, January 1990

  • Biglari, H.; Diamond, P. H.; Terry, P. W.
  • Physics of Fluids B: Plasma Physics, Vol. 2, Issue 1
  • DOI: 10.1063/1.859529

Suppression of turbulence and transport by sheared flow
journal, January 2000


Stationary Spectrum of Strong Turbulence in Magnetized Nonuniform Plasma
journal, July 1977


Zonal Flows and Transient Dynamics of the L H Transition
journal, May 2003


Wave-number spectrum of dissipative drift waves and a transition scale
journal, September 2015


Bifurcation in electrostatic resistive drift wave turbulence
text, January 2007


Zonal flow generation and its feedback on turbulence production in drift wave turbulence
text, January 2012


Works referencing / citing this record:

Edge turbulence evolution and intermittency development near the density limit on the HL-2A tokamak
journal, September 2019

  • Wang, L.; Tynan, G. R.; Hong, R.
  • Physics of Plasmas, Vol. 26, Issue 9
  • DOI: 10.1063/1.5100176

Studies of Reynolds stress and the turbulent generation of edge poloidal flows on the HL-2A tokamak
journal, August 2019