skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Modelling enhanced confinement in drift-wave turbulence

Abstract

Here, the results of modeling studies of an enhanced confinement in the drift wave turbulent plasma of the CSDX linear device are presented. The mechanism of enhanced confinement is investigated here using a reduced 1D, time-dependent model, which illustrates the exchange of enstrophy between two disparate scale structures: the mesoscale flow and profile, and the turbulence intensity fields. Mean density, mean vorticity, and turbulent potential enstrophy are the variables for this model. Total potential enstrophy is conserved in this model. Vorticity mixing occurs on a scale length related to an effective Rhines' scale of turbulence, and shrinks as both density and vorticity gradients steepen. Numerical results obtained from solution of the model agree well with the experimental data from CSDX showing: (i) a steepening of the mean density profile, indicating a radial transport barrier formation, (ii) the development of a radially sheared azimuthal flow velocity that coincides with the density steepening and initiates a turbulence quench, and (iii) negative Reynolds work values, indicating that fluctuations drive the shear flow. These observations as the magnitude of the magnetic field B increases are recovered using purely diffusive expressions for the vorticity and density fluxes. A new dimensionless turbulence parameter RDT-defined as themore » ratio of the integrated potential enstrophy transfer from turbulence to the flow, to the integrated potential enstrophy production due to relaxation of the density gradient is introduced as a turbulence collapse indicator that detects when the enhanced confinement state is triggered« less

Authors:
 [1];  [1];  [1];  [1]
  1. Univ. of California, San Diego, La Jolla, CA (United States)
Publication Date:
Research Org.:
Univ. of California, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1474292
Alternate Identifier(s):
OSTI ID: 1363708
Grant/Contract Number:  
SC0008378; FG02-04ER54738
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; 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., Ashourvan, A., and Tynan, G. R. Modelling enhanced confinement in drift-wave turbulence. United States: N. p., 2017. Web. doi:10.1063/1.4985323.
Hajjar, R. J., Diamond, P. H., Ashourvan, A., & Tynan, G. R. Modelling enhanced confinement in drift-wave turbulence. United States. doi:10.1063/1.4985323.
Hajjar, R. J., Diamond, P. H., Ashourvan, A., and Tynan, G. R. Mon . "Modelling enhanced confinement in drift-wave turbulence". United States. doi:10.1063/1.4985323. https://www.osti.gov/servlets/purl/1474292.
@article{osti_1474292,
title = {Modelling enhanced confinement in drift-wave turbulence},
author = {Hajjar, R. J. and Diamond, P. H. and Ashourvan, A. and Tynan, G. R.},
abstractNote = {Here, the results of modeling studies of an enhanced confinement in the drift wave turbulent plasma of the CSDX linear device are presented. The mechanism of enhanced confinement is investigated here using a reduced 1D, time-dependent model, which illustrates the exchange of enstrophy between two disparate scale structures: the mesoscale flow and profile, and the turbulence intensity fields. Mean density, mean vorticity, and turbulent potential enstrophy are the variables for this model. Total potential enstrophy is conserved in this model. Vorticity mixing occurs on a scale length related to an effective Rhines' scale of turbulence, and shrinks as both density and vorticity gradients steepen. Numerical results obtained from solution of the model agree well with the experimental data from CSDX showing: (i) a steepening of the mean density profile, indicating a radial transport barrier formation, (ii) the development of a radially sheared azimuthal flow velocity that coincides with the density steepening and initiates a turbulence quench, and (iii) negative Reynolds work values, indicating that fluctuations drive the shear flow. These observations as the magnitude of the magnetic field B increases are recovered using purely diffusive expressions for the vorticity and density fluxes. A new dimensionless turbulence parameter RDT-defined as the ratio of the integrated potential enstrophy transfer from turbulence to the flow, to the integrated potential enstrophy production due to relaxation of the density gradient is introduced as a turbulence collapse indicator that detects when the enhanced confinement state is triggered},
doi = {10.1063/1.4985323},
journal = {Physics of Plasmas},
number = 6,
volume = 24,
place = {United States},
year = {2017},
month = {6}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Save / Share:

Works referenced in this record:

Evidence for Convective Inward Particle Transport in a Stellarator
journal, February 1999


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


Turbulent-driven low-frequency sheared E × B flows as the trigger for the H-mode transition
journal, July 2013


Observation of turbulent-driven shear flow in a cylindrical laboratory plasma device
journal, March 2006


The origin of convective structures in the scrape-off layer of linear magnetic fusion devices investigated by fast imaging
journal, February 2007

  • Antar, G. Y.; Yu, J. H.; Tynan, G.
  • Physics of Plasmas, Vol. 14, Issue 2
  • DOI: 10.1063/1.2424886

Flow shear induced fluctuation suppression in finite aspect ratio shaped tokamak plasma
journal, May 1995

  • Hahm, T. S.; Burrell, K. H.
  • Physics of Plasmas, Vol. 2, Issue 5
  • DOI: 10.1063/1.871313

Spatio-temporal evolution of the L → I → H transition
journal, September 2012

  • Miki, K.; Diamond, P. H.; Gürcan, Ö. D.
  • Physics of Plasmas, Vol. 19, Issue 9
  • DOI: 10.1063/1.4753931

Resistive pressure‐gradient‐driven turbulence with self‐consistent flow profile evolution
journal, May 1993

  • Carreras, B. A.; Lynch, V. E.; Garcia, L.
  • Physics of Fluids B: Plasma Physics, Vol. 5, Issue 5
  • DOI: 10.1063/1.860889

Nonlinear energy transfer during the transition to drift-interchange turbulence
journal, July 2011


Length scales of turbulence in stably stratified mixing layers
journal, June 2000

  • Smyth, William D.; Moum, James N.
  • Physics of Fluids, Vol. 12, Issue 6
  • DOI: 10.1063/1.870385

On the transition to drift turbulence in a magnetized plasma column
journal, May 2005

  • Burin, M. J.; Tynan, G. R.; Antar, G. Y.
  • Physics of Plasmas, Vol. 12, Issue 5
  • DOI: 10.1063/1.1889443

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

Plasma Edge Turbulence
journal, February 1983


Linking the micro and macro: L-H transition dynamics and threshold physics
journal, March 2015

  • Malkov, M. A.; Diamond, P. H.; Miki, K.
  • Physics of Plasmas, Vol. 22, Issue 3
  • DOI: 10.1063/1.4914934

First Evidence of the Role of Zonal Flows for the L H Transition at Marginal Input Power in the EAST Tokamak
journal, September 2011


Intrinsic rotation generation in ELM-free H-mode plasmas in the DIII-D tokamak—Experimental observations
journal, July 2011

  • Müller, S. H.; Boedo, J. A.; Burrell, K. H.
  • Physics of Plasmas, Vol. 18, Issue 7
  • DOI: 10.1063/1.3605041

Chaos and turbulence studies in low- plasmas
journal, December 1997


Self-organization of electrostatic turbulence in a cylindrical plasma
journal, October 1987


Scaling properties of turbulence driven shear flow
journal, January 2010

  • Yan, Z.; Tynan, G. R.; Holland, C.
  • Physics of Plasmas, Vol. 17, Issue 1
  • DOI: 10.1063/1.3276521

Quiet periods in edge turbulence preceding the L-H transition in the National Spherical Torus Experiment
journal, October 2010

  • Zweben, S. J.; Maqueda, R. J.; Hager, R.
  • Physics of Plasmas, Vol. 17, Issue 10
  • DOI: 10.1063/1.3476276

Turbulent Equipartition and Homogenization of Plasma Angular Momentum
journal, April 2008


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

Turbulence in fusion plasmas: key issues and impact on transport modelling
journal, November 2001


Dynamics of interfaces and layers in a stratified turbulent fluid
journal, January 1998

  • Balmforth, N. J.; Llewellyn Smith, Stefan G.; Young, W. R.
  • Journal of Fluid Mechanics, Vol. 355
  • DOI: 10.1017/S0022112097007970

Experimental observation of coupling between turbulence and sheared flows during L-H transitions in a toroidal plasma
journal, November 2010


Multi-instability plasma dynamics during the route to fully developed turbulence in a helicon plasma
journal, July 2014


Drift waves and transport
journal, April 1999


Verification and validation in computational fluid dynamics
journal, April 2002


Turbulent transport of fast ions in the Large Plasma Device
journal, September 2010

  • Zhou, Shu; Heidbrink, W. W.; Boehmer, H.
  • Physics of Plasmas, Vol. 17, Issue 9
  • DOI: 10.1063/1.3486532

Negative viscosity from negative compressibility and axial flow shear stiffness in a straight magnetic field
journal, March 2017

  • Li, J. C.; Diamond, P. H.
  • Physics of Plasmas, Vol. 24, Issue 3
  • DOI: 10.1063/1.4978956

Spontaneous profile self-organization in a simple realization of drift-wave turbulence
journal, March 2016

  • Cui, L.; Ashourvan, A.; Thakur, S. C.
  • Physics of Plasmas, Vol. 23, Issue 5
  • DOI: 10.1063/1.4944819

Validation metrics for turbulent plasma transport
journal, June 2016


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


Zonal flows in plasma—a review
journal, April 2005


Structure formation in parallel ion flow and density profiles by cross-ferroic turbulent transport in linear magnetized plasma
journal, October 2016

  • Kobayashi, T.; Inagaki, S.; Kosuga, Y.
  • Physics of Plasmas, Vol. 23, Issue 10
  • DOI: 10.1063/1.4965915

Observations of abrupt changes in the fluctuation spectrum on LMD-U
journal, June 2009


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

Study of nonlinear spectral energy transfer in frequency domain
journal, April 2009

  • Xu, M.; Tynan, G. R.; Holland, C.
  • Physics of Plasmas, Vol. 16, Issue 4
  • DOI: 10.1063/1.3098538

Physics of non-diffusive turbulent transport of momentum and the origins of spontaneous rotation in tokamaks
journal, March 2009


Thermal confinement bifurcation and the L‐ to H‐mode transition in tokamaks
journal, March 1991

  • Hinton, F. L.
  • Physics of Fluids B: Plasma Physics, Vol. 3, Issue 3
  • DOI: 10.1063/1.859866

A Concept of Cross-Ferroic Plasma Turbulence
journal, February 2016

  • Inagaki, S.; Kobayashi, T.; Kosuga, Y.
  • Scientific Reports, Vol. 6, Issue 1
  • DOI: 10.1038/srep22189

Up-gradient particle flux in a drift wave-zonal flow system
journal, May 2015

  • Cui, L.; Tynan, G. R.; Diamond, P. H.
  • Physics of Plasmas, Vol. 22, Issue 5
  • DOI: 10.1063/1.4921671

Waves and turbulence on a beta-plane
journal, June 1975