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 selfconsistently 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$$—related to fluctuation intensity—is presented. Quasilinear analysis determines how the particle flux Γ_{n} and vorticity flux Π=–χ_{y}∇^{2}v_{y}+Π^{res} scale with α, in both hydrodynamic and adiabatic regimes. As the plasma response passes from adiabatic (α>1) to hydrodynamic (α<1), the particle flux Γ_{n} is enhanced and the turbulent viscosity χ_{y} increases. However, the residual flux Π^{res}—which drives the flow—drops with α. As a result, the mean vorticity gradient ∇^{2}$$\overline{v}$$_{y}=Π^{res}/χ_{y}—representative of the strength of the shear—also drops. The shear layer then collapses and turbulence is enhanced. The collapse is due to a decrease in ZF production, not an increase in damping. A physical picture for the onset of collapse is presented. The findings of this paper are used to motivate an explanation of the phenomenology of low β density limit evolution. A change from adiabatic (α=k$$^{2}_{z}$$v$$^{2}_{th}$$/(ων_{ei})>1) to hydrodynamic (α<1) electron dynamics is associated with the density limit.
 Authors:

 Univ. of California, San Diego, CA (United States)
 Univ. of California, San Diego, CA (United States); Southwestern Inst. of Physics, Chengdu (China)
 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:
 FG0204ER54738
 Resource Type:
 Accepted Manuscript
 Journal Name:
 Physics of Plasmas
 Additional Journal Information:
 Journal Volume: 25; Journal Issue: 6; Journal ID: ISSN 1070664X
 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. doi: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. doi: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 selfconsistently 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$—related to fluctuation intensity—is presented. Quasilinear analysis determines how the particle flux Γn and vorticity flux Π=–χy∇2vy+Πres scale with α, in both hydrodynamic and adiabatic regimes. As the plasma response passes from adiabatic (α>1) to hydrodynamic (α<1), the particle flux Γn is enhanced and the turbulent viscosity χy increases. However, the residual flux Πres—which drives the flow—drops with α. As a result, the mean vorticity gradient ∇2$\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}$/(ωνei)>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 = {2018},
month = {6}
}
Web of Science
Works referenced in this record:
Edge shear flows and particle transport near the density limit of the HL2A tokamak
journal, December 2017
 Hong, R.; Tynan, G. R.; Diamond, P. H.
 Nuclear Fusion, Vol. 58, Issue 1
Momentum theorems and the structure of atmospheric jets and zonal flows in plasmas
journal, November 2008
 Diamond, P. H.; Gurcan, O. D.; Hahm, T. S.
 Plasma Physics and Controlled Fusion, Vol. 50, Issue 12
FrequencyResolved Nonlinear Turbulent Energy Transfer into Zonal Flows in Strongly Heated $L$ Mode Plasmas in the HL2A Tokamak
journal, June 2012
 Xu, M.; Tynan, G. R.; Diamond, P. H.
 Physical Review Letters, Vol. 108, Issue 24
Longrange correlations and edge transport bifurcation in fusion plasmas
journal, May 2011
 Xu, Y.; Carralero, D.; Hidalgo, C.
 Nuclear Fusion, Vol. 51, Issue 6
An interpretation of fluctuation induced transport derived from electrostatic probe measurements
journal, April 2002
 LaBombard, B.
 Physics of Plasmas, Vol. 9, Issue 4
Resistive drift‐wave turbulence
journal, January 1995
 Camargo, Suzana J.; Biskamp, Dieter; Scott, Bruce D.
 Physics of Plasmas, Vol. 2, Issue 1
Numerical investigation of frequency spectrum in the HasegawaWakatani model
journal, October 2013
 Kim, Juhyung; Terry, P. W.
 Physics of Plasmas, Vol. 20, Issue 10
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
Imode: an Hmode energy confinement regime with Lmode particle transport in Alcator CMod
journal, August 2010
 Whyte, D. G.; Hubbard, A. E.; Hughes, J. W.
 Nuclear Fusion, Vol. 50, Issue 10
Density limits in toroidal plasmas
journal, July 2002
 Greenwald, Martin
 Plasma Physics and Controlled Fusion, Vol. 44, Issue 8
Physical Mechanism behind ZonalFlow Generation in DriftWave Turbulence
journal, October 2009
 Manz, P.; Ramisch, M.; Stroth, U.
 Physical Review Letters, Vol. 103, Issue 16
A new look at density limits in tokamaks
journal, December 1988
 Greenwald, M.; Terry, J. L.; Wolfe, S. M.
 Nuclear Fusion, Vol. 28, Issue 12
Plasma Edge Turbulence
journal, February 1983
 Hasegawa, Akira; Wakatani, Masahiro
 Physical Review Letters, Vol. 50, Issue 9
How mesoscopic staircases condense to macroscopic barriers in confined plasma turbulence
journal, November 2016
 Ashourvan, Arash; Diamond, P. H.
 Physical Review E, Vol. 94, Issue 5
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
Collisional Scaling of the Energy Transfer in DriftWave Zonal Flow Turbulence
journal, January 2017
 Schmid, B.; Manz, P.; Ramisch, M.
 Physical Review Letters, Vol. 118, Issue 5
Zonal flow triggers the LH 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
Energetics of the interaction between electromagnetic ExB turbulence and zonal flows
journal, January 2005
 Scott, Bruce D.
 New Journal of Physics, Vol. 7
Bifurcation in electrostatic resistive drift wave turbulence
journal, October 2007
 Numata, Ryusuke; Ball, Rowena; Dewar, Robert L.
 Physics of Plasmas, Vol. 14, Issue 10
Synergy of Anomalous Transport and Radiation in the Density Limit
journal, August 2003
 Tokar, M. Z.
 Physical Review Letters, Vol. 91, Issue 9
Drift waves and transport
journal, April 1999
 Horton, W.
 Reviews of Modern Physics, Vol. 71, Issue 3
Phase Space of Tokamak Edge Turbulence, the $\mathit{L}\mathit{H}$ Transition, and the Formation of the Edge Pedestal
journal, November 1998
 Rogers, B. N.; Drake, J. F.; Zeiler, A.
 Physical Review Letters, Vol. 81, Issue 20
Zonal flows in plasma—a review
journal, April 2005
 Diamond, P. H.; Itoh, SI; Itoh, K.
 Plasma Physics and Controlled Fusion, Vol. 47, Issue 5
Role of Zonal Flow PredatorPrey Oscillations in Triggering the Transition to HMode Confinement
journal, April 2012
 Schmitz, L.; Zeng, L.; Rhodes, T. L.
 Physical Review Letters, Vol. 108, Issue 15
Modelling enhanced confinement in driftwave turbulence
journal, June 2017
 Hajjar, R. J.; Diamond, P. H.; Ashourvan, A.
 Physics of Plasmas, Vol. 24, Issue 6
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
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
Suppression of turbulence and transport by sheared flow
journal, January 2000
 Terry, P. W.
 Reviews of Modern Physics, Vol. 72, Issue 1
Stationary Spectrum of Strong Turbulence in Magnetized Nonuniform Plasma
journal, July 1977
 Hasegawa, Akira; Mima, Kunioki
 Physical Review Letters, Vol. 39, Issue 4
Zonal Flows and Transient Dynamics of the $L\mathrm{\text{\u2212}}H$ Transition
journal, May 2003
 Kim, Eunjin; Diamond, P. H.
 Physical Review Letters, Vol. 90, Issue 18
Wavenumber spectrum of dissipative drift waves and a transition scale
journal, September 2015
 Ghantous, K.; Gürcan, Ö. D.
 Physical Review E, Vol. 92, Issue 3
Role of thermal instabilities and anomalous transport in threshold of detachment and multifacetted asymmetric radiation from the edge (MARFE)
journal, May 2005
 Tokar, M. Z.; Kelly, F. A.; Loozen, X.
 Physics of Plasmas, Vol. 12, Issue 5
Works referencing / citing this record:
Edge turbulence evolution and intermittency development near the density limit on the HL2A tokamak
journal, September 2019
 Wang, L.; Tynan, G. R.; Hong, R.
 Physics of Plasmas, Vol. 26, Issue 9
Studies of Reynolds stress and the turbulent generation of edge poloidal flows on the HL2A tokamak
journal, August 2019
 Long, T.; Diamond, P. H.; Xu, M.
 Nuclear Fusion, Vol. 59, Issue 10