Long-lived predator-prey dynamics in the pedestal of near-zero torque high performance DIII-D plasmas

Barada, K.; Rhodes, T. L.; Burrell, K. H.; Zeng, L.; Chen, Xi; Austin, M. E.; Bardóczi, L.; Muscatello, C. M.; Peebles, W. A.

doi:10.1063/1.5097143

Title: Long-lived predator-prey dynamics in the pedestal of near-zero torque high performance DIII-D plasmas

Abstract

Quiescent high performance plasmas (often termed QH-mode) are attractive due to the replacement of potentially damaging energy and particle releases known as edge localized modes by relatively benign edge harmonic oscillations (EHOs). These EHOs are believed to be driven unstable by edge current and/or edge toroidal rotational shear and contribute to edge particle transport. Decreasing the applied neutral beam torque in standard QH-mode discharge leads to an improved quiescent phase of higher and wider pedestal, also known as the wide-pedestal QH-mode [Burrell et al., Phys. Plasmas 23, 056103 (2016)]. This work expands upon the observed limit cycle oscillation (LCO) dynamics [Barada et al., Phys. Rev. Lett. 120, 135002 (2018)] in this wide pedestal QH-mode. The onset of these LCOs after wide-pedestal transition is found to be correlated with the disappearance of coherent EHOs which happens either when the edge maximum bootstrap current decreases after the transition or when the toroidal rotation is decreased consistent with simulation predictions. Sustainment of this quasistationary oscillating regime is found to be possible due to a predator-prey type competition between E × B velocity shear and turbulence density fluctuations facilitated by an inward propagation of nonzonal flow like toroidally and poloidally symmetric E × B velocity perturbations from thesemore »« less

Authors:

^[1]; Rhodes, T. L. ^[1];

^[2];

^[1];

^[2];

^[3]; Bardóczi, L. ^[2];

^[2]; Peebles, W. A. ^[1]

Univ. of California, Los Angeles, CA (United States)
General Atomics, San Diego, CA (United States)
Univ. of Texas, Austin, TX (United States)

Publication Date:: Thu Sep 05 00:00:00 EDT 2019

Research Org.:: General Atomics, San Diego, CA (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

OSTI Identifier:: 1560136

Alternate Identifier(s):: OSTI ID: 1560341

Report Number(s):: DOE-GA-54698
Journal ID: ISSN 1070-664X; TRN: US2000462

Grant/Contract Number:: FC02-04ER54698; FG02-08ER54984

Resource Type:: Accepted Manuscript

Journal Name:: Physics of Plasmas

Additional Journal Information:: Journal Volume: 26; Journal Issue: 9; 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


                    Barada, K., Rhodes, T. L., Burrell, K. H., Zeng, L., Chen, Xi, Austin, M. E., Bardóczi, L., Muscatello, C. M., and Peebles, W. A. Long-lived predator-prey dynamics in the pedestal of near-zero torque high performance DIII-D plasmas.  United States: N. p., 2019. 
Web.  doi:10.1063/1.5097143.

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                    Barada, K., Rhodes, T. L., Burrell, K. H., Zeng, L., Chen, Xi, Austin, M. E., Bardóczi, L., Muscatello, C. M., & Peebles, W. A. Long-lived predator-prey dynamics in the pedestal of near-zero torque high performance DIII-D plasmas.  United States.  https://doi.org/10.1063/1.5097143

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                    Barada, K., Rhodes, T. L., Burrell, K. H., Zeng, L., Chen, Xi, Austin, M. E., Bardóczi, L., Muscatello, C. M., and Peebles, W. A. Thu .  
"Long-lived predator-prey dynamics in the pedestal of near-zero torque high performance DIII-D plasmas".  United States.  https://doi.org/10.1063/1.5097143.  https://www.osti.gov/servlets/purl/1560136.

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@article{osti_1560136,

  title        = {Long-lived predator-prey dynamics in the pedestal of near-zero torque high performance DIII-D plasmas},

  author       = {Barada, K. and Rhodes, T. L. and Burrell, K. H. and Zeng, L. and Chen, Xi and Austin, M. E. and Bardóczi, L. and Muscatello, C. M. and Peebles, W. A.},

  abstractNote = {Quiescent high performance plasmas (often termed QH-mode) are attractive due to the replacement of potentially damaging energy and particle releases known as edge localized modes by relatively benign edge harmonic oscillations (EHOs). These EHOs are believed to be driven unstable by edge current and/or edge toroidal rotational shear and contribute to edge particle transport. Decreasing the applied neutral beam torque in standard QH-mode discharge leads to an improved quiescent phase of higher and wider pedestal, also known as the wide-pedestal QH-mode [Burrell et al., Phys. Plasmas 23, 056103 (2016)]. This work expands upon the observed limit cycle oscillation (LCO) dynamics [Barada et al., Phys. Rev. Lett. 120, 135002 (2018)] in this wide pedestal QH-mode. The onset of these LCOs after wide-pedestal transition is found to be correlated with the disappearance of coherent EHOs which happens either when the edge maximum bootstrap current decreases after the transition or when the toroidal rotation is decreased consistent with simulation predictions. Sustainment of this quasistationary oscillating regime is found to be possible due to a predator-prey type competition between E × B velocity shear and turbulence density fluctuations facilitated by an inward propagation of nonzonal flow like toroidally and poloidally symmetric E × B velocity perturbations from these LCOs. These LCO dynamics are further controlled by adding electron cyclotron heating (ECH) to a neutral beam heated wide-pedestal QH-mode discharge which led to a surprising increase in energy confinement correlated with a concomitant decrease in edge turbulence in contrast to normally observed confinement degradation in H-mode with ECH.},

  doi          = {10.1063/1.5097143},

  journal      = {Physics of Plasmas},

  number       = 9,

  volume       = 26,

  place        = {United States},

  year         = {Thu Sep 05 00:00:00 EDT 2019},

  month        = {Thu Sep 05 00:00:00 EDT 2019}

}

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Title: Long-lived predator-prey dynamics in the pedestal of near-zero torque high performance DIII-D plasmas

Abstract

Citation Formats

Low–intermediate–high confinement transition in HL-2A tokamak plasmas journal, November 2014

Development of an Edge Transport Barrier at the H-Mode Transition of ASDEX journal, October 1984

Particle transport in low-collisionality H-mode plasmas on DIII-D journal, September 2015

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

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Edge localized modes (ELMs) journal, February 1996

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Fluctuation spectra and velocity profile from Doppler backscattering on Tore Supra journal, August 2006

Stability and dynamics of the edge pedestal in the low collisionality regime: physics mechanisms for steady-state ELM-free operation journal, August 2007

Advances in understanding quiescent H-mode plasmas in DIII-D journal, May 2005

Studies of the ‘Quiescent H-mode’ regime in ASDEX Upgrade and JET journal, July 2005

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

Amplitude-Dependent Frequency, Desynchronization, and Stabilization in Noisy Metapopulation Dynamics journal, February 2007

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

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Doppler reflectometry with optimized temporal resolution for the measurement of turbulence and its propagation velocity journal, March 2004

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The Ten-Year Cycle in Numbers of the Lynx in Canada journal, November 1942

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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

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

Understanding ECH density pump-out in DIII-D H-mode plasmas journal, August 2017

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A theory-based transport model with comprehensive physics journal, May 2007

Plasma rotation profile measurements using Doppler reflectometry journal, April 2004

Discovery of stationary operation of quiescent H-mode plasmas with net-zero neutral beam injection torque and high energy confinement on DIII-D journal, March 2016

Low–intermediate–high confinement transition in HL-2A tokamak plasmas
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Development of an Edge Transport Barrier at the H-Mode Transition of ASDEX
journal, October 1984

Particle transport in low-collisionality H-mode plasmas on DIII-D
journal, September 2015

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

A multichannel, frequency-modulated, tunable Doppler backscattering and reflectometry system
journal, August 2009

Doppler backscattering for spherical tokamaks and measurement of high- k density fluctuation wavenumber spectrum in MAST
journal, June 2015

Edge localized modes (ELMs)
journal, February 1996

Quasistationary Plasma Predator-Prey System of Coupled Turbulence, Drive, and Sheared $E \times B$ Flow During High Performance DIII-D Tokamak Discharges
journal, March 2018

Fluctuation spectra and velocity profile from Doppler backscattering on Tore Supra
journal, August 2006

Stability and dynamics of the edge pedestal in the low collisionality regime: physics mechanisms for steady-state ELM-free operation
journal, August 2007

Advances in understanding quiescent H-mode plasmas in DIII-D
journal, May 2005

Studies of the ‘Quiescent H-mode’ regime in ASDEX Upgrade and JET
journal, July 2005

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

Amplitude-Dependent Frequency, Desynchronization, and Stabilization in Noisy Metapopulation Dynamics
journal, February 2007

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

Spatial Instabilities within the Diffusive Lotka-Volterra System: Individual-Based Simulation Results
journal, February 1993

Doppler reflectometry with optimized temporal resolution for the measurement of turbulence and its propagation velocity
journal, March 2004

Doppler backscattering system for measuring fluctuations and their perpendicular velocity on Tore Supra
journal, October 2004

Correlations between quasi-coherent fluctuations and the pedestal evolution during the inter-edge localized modes phase on DIII-Da)
journal, May 2015

Local migration promotes competitive restraint in a host–pathogen 'tragedy of the commons'
journal, July 2006

A design retrospective of the DIII-D tokamak
journal, May 2002

Chapter 1: Overview and summary
journal, December 1999

Impurity confinement and transport in high confinement regimes without edge localized modes on DIII-Da)
journal, May 2015

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journal, July 2013

Stationary QH-mode plasmas with high and wide pedestal at low rotation on DIII-D
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journal, November 2010

Dynamics of low to high (‘‘L’’ to ‘‘H’’) confinement bifurcation: Poloidal flow and ion pressure gradient evolution
journal, December 1994

Impact of toroidal rotation on ELM behaviour in the H-mode on JT-60U
journal, April 2004

A novel, multichannel, comb-frequency Doppler backscatter system
journal, October 2010

The Ten-Year Cycle in Numbers of the Lynx in Canada
journal, November 1942

An eight-channel Doppler backscattering system in the experimental advanced superconducting tokamak
journal, July 2017

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

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

Understanding ECH density pump-out in DIII-D H-mode plasmas
journal, August 2017

Characteristics of type I ELM energy and particle losses in existing devices and their extrapolation to ITER
journal, August 2003

A theory-based transport model with comprehensive physics
journal, May 2007

Plasma rotation profile measurements using Doppler reflectometry
journal, April 2004

Discovery of stationary operation of quiescent H-mode plasmas with net-zero neutral beam injection torque and high energy confinement on DIII-D
journal, March 2016