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Title: Intermittent fluctuations in the Alcator C-Mod scrape-off layer for ohmic and high confinement mode plasmas

Abstract

Plasma fluctuations in the scrape-off layer of the Alcator C-Mod tokamak in ohmic and high confinement modes have been analyzed using gas puff imaging data. In all cases investigated, the time series of emission from a single spatially resolved view into the gas puff are dominated by large-amplitude bursts, attributed to blob-like filament structures moving radially outwards and poloidally. There is a remarkable similarity of the fluctuation statistics in ohmic plasmas and in edge localized mode-free and enhanced D-alpha high confinement mode plasmas. Conditionally averaged waveforms have a two-sided exponential shape with comparable temporal scales and asymmetry, while the burst amplitudes and the waiting times between them are exponentially distributed. The probability density functions and the frequency power spectral densities are similar for all these confinement modes. These results provide strong evidence in support of a stochastic model describing the plasma fluctuations in the scrape-off layer as a super-position of uncorrelated exponential pulses. Predictions of this model are in excellent agreement with experimental measurements in both ohmic and high confinement mode plasmas. Finally, the stochastic model thus provides a valuable tool for predicting fluctuation-induced plasma–wall interactions in magnetically confined fusion plasmas.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1];  [2]; ORCiD logo [2]
  1. UiT The Arctic Univ. of Norway, Tromsø (Norway). Dept. of Physics and Technology
  2. Massachusetts Inst. of Technology, Cambridge, MA (United States). Plasma Science and Fusion Center
Publication Date:
Research Org.:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1540162
Alternate Identifier(s):
OSTI ID: 1427326
Grant/Contract Number:  
FC02-99ER54512; FC02-99ER54512- CMOD
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 25; Journal Issue: 5; 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; physics

Citation Formats

Garcia, O. E., Kube, R., Theodorsen, A., LaBombard, B., and Terry, J. L. Intermittent fluctuations in the Alcator C-Mod scrape-off layer for ohmic and high confinement mode plasmas. United States: N. p., 2018. Web. doi:10.1063/1.5018709.
Garcia, O. E., Kube, R., Theodorsen, A., LaBombard, B., & Terry, J. L. Intermittent fluctuations in the Alcator C-Mod scrape-off layer for ohmic and high confinement mode plasmas. United States. doi:10.1063/1.5018709.
Garcia, O. E., Kube, R., Theodorsen, A., LaBombard, B., and Terry, J. L. Sun . "Intermittent fluctuations in the Alcator C-Mod scrape-off layer for ohmic and high confinement mode plasmas". United States. doi:10.1063/1.5018709. https://www.osti.gov/servlets/purl/1540162.
@article{osti_1540162,
title = {Intermittent fluctuations in the Alcator C-Mod scrape-off layer for ohmic and high confinement mode plasmas},
author = {Garcia, O. E. and Kube, R. and Theodorsen, A. and LaBombard, B. and Terry, J. L.},
abstractNote = {Plasma fluctuations in the scrape-off layer of the Alcator C-Mod tokamak in ohmic and high confinement modes have been analyzed using gas puff imaging data. In all cases investigated, the time series of emission from a single spatially resolved view into the gas puff are dominated by large-amplitude bursts, attributed to blob-like filament structures moving radially outwards and poloidally. There is a remarkable similarity of the fluctuation statistics in ohmic plasmas and in edge localized mode-free and enhanced D-alpha high confinement mode plasmas. Conditionally averaged waveforms have a two-sided exponential shape with comparable temporal scales and asymmetry, while the burst amplitudes and the waiting times between them are exponentially distributed. The probability density functions and the frequency power spectral densities are similar for all these confinement modes. These results provide strong evidence in support of a stochastic model describing the plasma fluctuations in the scrape-off layer as a super-position of uncorrelated exponential pulses. Predictions of this model are in excellent agreement with experimental measurements in both ohmic and high confinement mode plasmas. Finally, the stochastic model thus provides a valuable tool for predicting fluctuation-induced plasma–wall interactions in magnetically confined fusion plasmas.},
doi = {10.1063/1.5018709},
journal = {Physics of Plasmas},
number = 5,
volume = 25,
place = {United States},
year = {2018},
month = {5}
}

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Works referenced in this record:

Visible imaging of turbulence in the SOL of the Alcator C-Mod tokamak
journal, March 2001


The influence of blobs on neutral particles in the scrape-off layer
journal, March 2016

  • Thrysøe, Alexander S.; Tophøj, Laust E. H.; Naulin, Volker
  • Plasma Physics and Controlled Fusion, Vol. 58, Issue 4
  • DOI: 10.1088/0741-3335/58/4/044010

Fluctuations and transport in the TCV scrape-off layer
journal, June 2007


Interpretation of fast measurements of plasma potential, temperature and density in SOL of ASDEX Upgrade
journal, August 2010


Radial transport in the far scrape-off layer of ASDEX Upgrade during L-mode and ELMy H-mode
journal, April 2013


Plasma edge cross-field transport: experiment and theory
journal, March 2005


Overview of edge electrostatic turbulence experiments on TCV
journal, March 2005


Burst statistics in Alcator C-Mod SOL turbulence
journal, July 2013


Blob Transport in the Plasma Edge: a Review
journal, January 2009


Intermittent fluctuations in the Alcator C-Mod scrape-off layer
journal, May 2013

  • Garcia, O. E.; Fritzner, S. M.; Kube, R.
  • Physics of Plasmas, Vol. 20, Issue 5
  • DOI: 10.1063/1.4802942

Edge transport studies in the edge and scrape-off layer of the National Spherical Torus Experiment with Langmuir probes
journal, April 2014

  • Boedo, J. A.; Myra, J. R.; Zweben, S.
  • Physics of Plasmas, Vol. 21, Issue 4
  • DOI: 10.1063/1.4873390

Density limits in toroidal plasmas
journal, July 2002


Probability distribution functions for intermittent scrape-off layer plasma fluctuations
journal, January 2018


Plasma–surface interaction, scrape-off layer and divertor physics: implications for ITER
journal, August 2007


An experimental investigation of the high density transition of the scrape-off layer transport in ASDEX Upgrade
journal, November 2014


Level crossings and excess times due to a superposition of uncorrelated exponential pulses
journal, January 2018


Assessment of the effects of scrape-off layer fluctuations on first wall sputtering with the TOKAM-2D turbulence code
journal, September 2016


Edge and SOL turbulence and blob variations over a large database in NSTX
journal, September 2015


Transport phenomena in the edge of Alcator C-Mod plasmas
journal, October 2005


Convergence of statistical moments of particle density time series in scrape-off layer plasmas
journal, January 2015

  • Kube, R.; Garcia, O. E.
  • Physics of Plasmas, Vol. 22, Issue 1
  • DOI: 10.1063/1.4905513

On the relation between non-exponential scrape off layer profiles and the dynamics of filaments
journal, October 2016


Inter-ELM filaments and turbulent transport in the Mega-Amp Spherical Tokamak
journal, January 2009


Experimental and numerical characterization of the turbulence in the scrape-off layer of MAST
journal, January 2013


Relationship between frequency power spectra and intermittent, large-amplitude bursts in the Alcator C-Mod scrape-off layer
journal, August 2017


Scrape-off layer turbulence in TCV: evidence in support of stochastic modelling
journal, January 2016


Filament transport, warm ions and erosion in ASDEX Upgrade L-modes
journal, February 2015


Auto-correlation function and frequency spectrum due to a super-position of uncorrelated exponential pulses
journal, March 2017

  • Garcia, O. E.; Theodorsen, A.
  • Physics of Plasmas, Vol. 24, Issue 3
  • DOI: 10.1063/1.4978955

Blob structure and motion in the edge and SOL of NSTX
journal, January 2016

  • Zweben, S. J.; Myra, J. R.; Davis, W. M.
  • Plasma Physics and Controlled Fusion, Vol. 58, Issue 4, Article No. 044007
  • DOI: 10.1088/0741-3335/58/4/044007

Ion-cyclotron range of frequencies in the scrape-off-layer: fine structure radial electric fields
journal, September 2012


Overview of experimental results and code validation activities at Alcator C-Mod
journal, September 2013


Transport by intermittency in the boundary of the DIII-D tokamak
journal, May 2003

  • Boedo, J. A.; Rudakov, D. L.; Moyer, R. A.
  • Physics of Plasmas, Vol. 10, Issue 5
  • DOI: 10.1063/1.1563259

Transport by intermittent convection in the boundary of the DIII-D tokamak
journal, November 2001

  • Boedo, J. A.; Rudakov, D.; Moyer, R.
  • Physics of Plasmas, Vol. 8, Issue 11
  • DOI: 10.1063/1.1406940

Experimental studies of edge turbulence and confinement in Alcator C-Mod
journal, May 2010

  • Cziegler, I.; Terry, J. L.; Hughes, J. W.
  • Physics of Plasmas, Vol. 17, Issue 5
  • DOI: 10.1063/1.3421577

Material erosion and migration in tokamaks
journal, November 2005


Intermittent fluctuations in the TCV scrape-off layer
journal, May 2015


Filament structures at the plasma edge on MAST
journal, November 2006


Transport of neutral particles in turbulent scrape-off layer plasmas
journal, July 2011


First results from Alcator‐C‐MOD*
journal, May 1994

  • Hutchinson, I. H.; Boivin, R.; Bombarda, F.
  • Physics of Plasmas, Vol. 1, Issue 5
  • DOI: 10.1063/1.870701

Blob/hole formation and zonal-flow generation in the edge plasma of the JET tokamak
journal, August 2009


20 years of research on the Alcator C-Mod tokamaka)
journal, November 2014

  • Greenwald, M.; Bader, A.; Baek, S.
  • Physics of Plasmas, Vol. 21, Issue 11
  • DOI: 10.1063/1.4901920

Impact of neutral density fluctuations on gas puff imaging diagnostics
journal, August 2017


Statistical analysis of the ion flux to the JET outer wall
journal, January 2017


A study on the density shoulder formation in the SOL of H-mode plasmas
journal, August 2017


Interpretation of scrape-off layer profile evolution and first-wall ion flux statistics on JET using a stochastic framework based on fillamentary motion
journal, June 2017

  • Walkden, N. R.; Wynn, A.; Militello, F.
  • Plasma Physics and Controlled Fusion, Vol. 59, Issue 8
  • DOI: 10.1088/1361-6587/aa7365

Plasma–surface interaction issues of an all-metal ITER
journal, February 2009


Scrape off layer profiles interpreted with filament dynamics
journal, August 2016


Experimental Validation of a Filament Transport Model in Turbulent Magnetized Plasmas
journal, November 2015


Statistical properties of a filtered Poisson process with additive random noise: distributions, correlations and moment estimation
journal, April 2017


Towards a consistent modelling of plasma edge turbulence in mean field transport codes: Focus on sputtering and plasma fluctuations
journal, August 2017


Fluctuation statistics in the scrape-off layer of Alcator C-Mod
journal, March 2016


SOL width and intermittent fluctuations in KSTAR
journal, August 2017


Stochastic Modeling of Intermittent Scrape-Off Layer Plasma Fluctuations
journal, June 2012


Invited Review Article: Gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion devices
journal, April 2017

  • Zweben, S. J.; Terry, J. L.; Stotler, D. P.
  • Review of Scientific Instruments, Vol. 88, Issue 4
  • DOI: 10.1063/1.4981873

Particle transport in the scrape-off layer and its relationship to discharge density limit in Alcator C-Mod
journal, May 2001

  • LaBombard, B.; Boivin, R. L.; Greenwald, M.
  • Physics of Plasmas, Vol. 8, Issue 5
  • DOI: 10.1063/1.1352596

New insights on boundary plasma turbulence and the quasi-coherent mode in Alcator C-Mod using a Mirror Langmuir Probe
journal, May 2014

  • LaBombard, B.; Golfinopoulos, T.; Terry, J. L.
  • Physics of Plasmas, Vol. 21, Issue 5
  • DOI: 10.1063/1.4873918

Level crossings, excess times, and transient plasma–wall interactions in fusion plasmas
journal, April 2016

  • Theodorsen, A.; Garcia, O. E.
  • Physics of Plasmas, Vol. 23, Issue 4
  • DOI: 10.1063/1.4947235

Collisionality dependent transport in TCV SOL plasmas
journal, November 2007


Fluctuation-driven transport in the DIII-D boundary
journal, May 2002

  • Rudakov, D. L.; Boedo, J. A.; Moyer, R. A.
  • Plasma Physics and Controlled Fusion, Vol. 44, Issue 6
  • DOI: 10.1088/0741-3335/44/6/308

Statistical characterization of turbulence in the boundary plasma of EAST
journal, October 2013


Blob properties in L- and H-mode from gas-puff imaging in ASDEX upgrade
journal, October 2014


Turbulence during H- and L-mode plasmas in the scrape-off layer of the ASDEX Upgrade tokamak
journal, July 2008


Self-similar density turbulence in the TCV tokamak scrape-off layer
journal, February 2005


Tokamak edge plasma simulation including anomalous cross-field convective transport
journal, April 2002

  • Pigarov, A. Yu.; Krasheninnikov, S. I.; Rognlien, T. D.
  • Physics of Plasmas, Vol. 9, Issue 4
  • DOI: 10.1063/1.1459059

Intermittency in the scrape-off layer of the National Spherical Torus Experiment during H-mode confinement
journal, August 2011


Effect of discrete coherent structures on plasma-wall interactions in the scrape-off-layer
journal, August 2008

  • D’Ippolito, D. A.; Myra, J. R.
  • Physics of Plasmas, Vol. 15, Issue 8
  • DOI: 10.1063/1.2974802

Statistical analysis of fluctuation characteristics at high- and low-field sides in L-mode SOL plasmas of JT-60U
journal, May 2009


Universality of intermittent convective transport in the scrape-off layer of magnetically confined devices
journal, February 2003

  • Antar, Ghassan Y.; Counsell, Glenn; Yu, Yang
  • Physics of Plasmas, Vol. 10, Issue 2
  • DOI: 10.1063/1.1536166

Neutral transport simulations of gas puff imaging experiments
journal, March 2003


Far SOL transport and main wall plasma interaction in DIII-D
journal, November 2005


Convective transport by intermittent blob-filaments: Comparison of theory and experiment
journal, June 2011

  • D’Ippolito, D. A.; Myra, J. R.; Zweben, S. J.
  • Physics of Plasmas, Vol. 18, Issue 6
  • DOI: 10.1063/1.3594609

The magnitude of plasma flux to the main-wall in the DIII-D tokamak
journal, September 2005

  • Whyte, D. G.; Lipschultz, B. L.; Stangeby, P. C.
  • Plasma Physics and Controlled Fusion, Vol. 47, Issue 10
  • DOI: 10.1088/0741-3335/47/10/002

    Works referencing / citing this record:

    Universality of Poisson-driven plasma fluctuations in the Alcator C-Mod scrape-off layer
    journal, December 2018

    • Theodorsen, A.; Garcia, O. E.; Kube, R.
    • Physics of Plasmas, Vol. 25, Issue 12
    • DOI: 10.1063/1.5064744

    Filament-assisted mode conversion in magnetized plasmas
    journal, January 2020

    • Tierens, W.; Zhang, W.; Myra, J. R.
    • Physics of Plasmas, Vol. 27, Issue 1
    • DOI: 10.1063/1.5128070

    Three-dimensional plasma edge turbulence simulations of the Mega Ampere Spherical Tokamak and comparison with experimental measurements
    journal, August 2019

    • Riva, Fabio; Militello, Fulvio; Elmore, Sarah
    • Plasma Physics and Controlled Fusion, Vol. 61, Issue 9
    • DOI: 10.1088/1361-6587/ab3561