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Title: Direct gyrokinetic comparison of pedestal transport in JET with carbon and ITER-like walls

Abstract

Our work compares the gyrokinetic instabilities and transport in two representative JET pedestals, one (pulse 78697) from the JET configuration with a carbon wall (C) and another (pulse 92432) from after the installation of JET's ITER-like Wall (ILW). The discharges were selected for a comparison of JET-ILW and JET-C discharges with good confinement at high current (3 MA, corresponding also to low ρ *) and retain the distinguishing features of JET-C and JET-ILW, notably, decreased pedestal top temperature for JET-ILW. A comparison of the profiles and heating power reveals a stark qualitative difference between the discharges: the JET-ILW pulse (92432) requires twice the heating power, at a gas rate of 1.9 × 10 22 e s -1, to sustain roughly half the temperature gradient of the JET-C pulse (78697), operated at zero gas rate. This points to heat transport as a central component of the dynamics limiting the JET-ILW pedestal and reinforces the following emerging JET-ILW pedestal transport paradigm, which is proposed for further examination by both theory and experiment. ILW conditions modify the density pedestal in ways that decrease the normalized pedestal density gradient a/L n , normally via an outward shift in relation to the temperature pedestal. Thismore » is attributable to some combination of direct metal wall effects and the need for increased fueling to mitigate tungsten contamination. The modification to the density profile increases η=L n/L γ, thereby producing more robust ion temperature gradient (ITG) and electron temperature gradient driven instability. The decreased pedestal gradients for JET-ILW (92432) also result in a strongly reduced E × B shear rate, further enhancing the ion scale turbulence. Collectively, these effects limit the pedestal temperature and demand more heating power to achieve good pedestal performance. Our simulations, consistent with basic theoretical arguments, find higher ITG turbulence, stronger stiffness, and higher pedestal transport in the ILW plasma at lower ρ *.« less

Authors:
ORCiD logo [1];  [1];  [1];  [1];  [2];  [2];  [2]; ORCiD logo [2]; ORCiD logo [3];  [2];  [2]
  1. Univ. of Texas, Austin, TX (United States)
  2. Culham Science Centre, Abingdon (United Kingdom). Culham Centre for Fusion Energy (CCFE)
  3. Forschungszentrum Juelich (Germany)
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC); Univ. of Texas, Austin, TX (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
Contributing Org.:
JET Contributors
OSTI Identifier:
1577625
Grant/Contract Number:  
FG02-04ER54742; SC0018429
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 59; Journal Issue: 8; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Hatch, D. R., Kotschenreuther, M., Mahajan, S. M., Merlo, G., Field, A. R., Giroud, C., Hillesheim, J. C., Maggi, C. F., Perez von Thun, C., Roach, C. M., and Saarelma, S. Direct gyrokinetic comparison of pedestal transport in JET with carbon and ITER-like walls. United States: N. p., 2019. Web. doi:10.1088/1741-4326/ab25bd.
Hatch, D. R., Kotschenreuther, M., Mahajan, S. M., Merlo, G., Field, A. R., Giroud, C., Hillesheim, J. C., Maggi, C. F., Perez von Thun, C., Roach, C. M., & Saarelma, S. Direct gyrokinetic comparison of pedestal transport in JET with carbon and ITER-like walls. United States. doi:10.1088/1741-4326/ab25bd.
Hatch, D. R., Kotschenreuther, M., Mahajan, S. M., Merlo, G., Field, A. R., Giroud, C., Hillesheim, J. C., Maggi, C. F., Perez von Thun, C., Roach, C. M., and Saarelma, S. Tue . "Direct gyrokinetic comparison of pedestal transport in JET with carbon and ITER-like walls". United States. doi:10.1088/1741-4326/ab25bd.
@article{osti_1577625,
title = {Direct gyrokinetic comparison of pedestal transport in JET with carbon and ITER-like walls},
author = {Hatch, D. R. and Kotschenreuther, M. and Mahajan, S. M. and Merlo, G. and Field, A. R. and Giroud, C. and Hillesheim, J. C. and Maggi, C. F. and Perez von Thun, C. and Roach, C. M. and Saarelma, S.},
abstractNote = {Our work compares the gyrokinetic instabilities and transport in two representative JET pedestals, one (pulse 78697) from the JET configuration with a carbon wall (C) and another (pulse 92432) from after the installation of JET's ITER-like Wall (ILW). The discharges were selected for a comparison of JET-ILW and JET-C discharges with good confinement at high current (3 MA, corresponding also to low ρ*) and retain the distinguishing features of JET-C and JET-ILW, notably, decreased pedestal top temperature for JET-ILW. A comparison of the profiles and heating power reveals a stark qualitative difference between the discharges: the JET-ILW pulse (92432) requires twice the heating power, at a gas rate of 1.9 × 1022 e s-1, to sustain roughly half the temperature gradient of the JET-C pulse (78697), operated at zero gas rate. This points to heat transport as a central component of the dynamics limiting the JET-ILW pedestal and reinforces the following emerging JET-ILW pedestal transport paradigm, which is proposed for further examination by both theory and experiment. ILW conditions modify the density pedestal in ways that decrease the normalized pedestal density gradient a/L n , normally via an outward shift in relation to the temperature pedestal. This is attributable to some combination of direct metal wall effects and the need for increased fueling to mitigate tungsten contamination. The modification to the density profile increases η=Ln/Lγ, thereby producing more robust ion temperature gradient (ITG) and electron temperature gradient driven instability. The decreased pedestal gradients for JET-ILW (92432) also result in a strongly reduced E × B shear rate, further enhancing the ion scale turbulence. Collectively, these effects limit the pedestal temperature and demand more heating power to achieve good pedestal performance. Our simulations, consistent with basic theoretical arguments, find higher ITG turbulence, stronger stiffness, and higher pedestal transport in the ILW plasma at lower ρ*.},
doi = {10.1088/1741-4326/ab25bd},
journal = {Nuclear Fusion},
number = 8,
volume = 59,
place = {United States},
year = {2019},
month = {7}
}

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Works referenced in this record:

Local and global Fokker–Planck neoclassical calculations showing flow and bootstrap current modification in a pedestal
journal, October 2012


Impact of nitrogen seeding on confinement and power load control of a high-triangularity JET ELMy H-mode plasma with a metal wall
journal, September 2013


Progress at JET in integrating ITER-relevant core and edge plasmas within the constraints of an ITER-like wall
journal, February 2015


Non-local effects on pedestal kinetic ballooning mode stability
journal, April 2017

  • Saarelma, S.; Martin-Collar, J.; Dickinson, D.
  • Plasma Physics and Controlled Fusion, Vol. 59, Issue 6
  • DOI: 10.1088/1361-6587/aa66ab

Electron temperature gradient driven turbulence
journal, May 2000

  • Jenko, F.; Dorland, W.; Kotschenreuther, M.
  • Physics of Plasmas, Vol. 7, Issue 5
  • DOI: 10.1063/1.874014

Kinetic Instabilities that Limit β in the Edge of a Tokamak Plasma: A Picture of an H -Mode Pedestal
journal, March 2012


Effects of impurities on electron temperature gradient modes
journal, September 2008


Pedestal evolution physics in low triangularity JET tokamak discharges with ITER-like wall
journal, November 2017


Particle pinch and collisionality in gyrokinetic simulations of tokamak plasma turbulence
journal, June 2009

  • Angioni, C.; Candy, J.; Fable, E.
  • Physics of Plasmas, Vol. 16, Issue 6
  • DOI: 10.1063/1.3155498

Dimensionless scalings of confinement, heat transport and pedestal stability in JET-ILW and comparison with JET-C
journal, October 2016


Overview of the JET results in support to ITER
journal, June 2017


Flux- and gradient-driven global gyrokinetic simulation of tokamak turbulence
journal, May 2011

  • Görler, Tobias; Lapillonne, Xavier; Brunner, Stephan
  • Physics of Plasmas, Vol. 18, Issue 5
  • DOI: 10.1063/1.3567484

Overview of the JET ITER-like Wall Project
journal, December 2010


Gyrokinetic study of ASDEX Upgrade inter-ELM pedestal profile evolution
journal, May 2015


Analysis of ELM stability with extended MHD models in JET, JT-60U and future JT-60SA tokamak plasmas
journal, November 2017


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

  • Diallo, A.; Groebner, R. J.; Rhodes, T. L.
  • Physics of Plasmas, Vol. 22, Issue 5
  • DOI: 10.1063/1.4921148

Simulations of density profiles, pellet fuelling and density control in ITER
journal, November 2011


Main ion and impurity edge profile evolution across the L- to H-mode transition on DIII-D
journal, August 2018

  • Haskey, S. R.; Grierson, B. A.; Chrystal, C.
  • Plasma Physics and Controlled Fusion, Vol. 60, Issue 10
  • DOI: 10.1088/1361-6587/aad702

Confinement and edge studies towards low ρ * and ν * at JET
journal, June 2013


Studies of the pedestal structure and inter-ELM pedestal evolution in JET with the ITER-like wall
journal, August 2017


Pedestal confinement and stability in JET-ILW ELMy H-modes
journal, September 2015


High frequency magnetic fluctuations correlated with the inter-ELM pedestal evolution in ASDEX Upgrade
journal, May 2016


Edge microstability of NSTX plasmas without and with lithium-coated plasma-facing components
journal, September 2013


Flow shear suppression of pedestal ion temperature gradient turbulence-A first principles theoretical framework
journal, June 2018

  • Hatch, D. R.; Hazeltine, R. D.; Kotschenreuther, M. K.
  • Plasma Physics and Controlled Fusion, Vol. 60, Issue 8
  • DOI: 10.1088/1361-6587/aac7a7

Scaling laws for edge plasma parameters in ITER from two-dimensional edge modelling
journal, August 2003


First scenario development with the JET new ITER-like wall
journal, December 2013


Plasma confinement at JET
journal, December 2015


Development and validation of a predictive model for the pedestal height
journal, May 2009

  • Snyder, P. B.; Groebner, R. J.; Leonard, A. W.
  • Physics of Plasmas, Vol. 16, Issue 5
  • DOI: 10.1063/1.3122146

The H-mode pedestal structure and its role on confinement in JET with a carbon and metal wall
journal, December 2014


The response of toroidal drift modes to profile evolution: a model for small-ELMs in tokamak plasmas?
journal, June 2016


Washboard modes as ELM-related events in JET
journal, November 2003

  • Perez, C. P.; Koslowski, H. R.; Hender, T. C.
  • Plasma Physics and Controlled Fusion, Vol. 46, Issue 1
  • DOI: 10.1088/0741-3335/46/1/005

Regime of Improved Confinement and High Beta in Neutral-Beam-Heated Divertor Discharges of the ASDEX Tokamak
journal, November 1982


High-accuracy characterization of the edge radial electric field at ASDEX Upgrade
journal, April 2013


Characterization of the H-mode edge barrier at ASDEX Upgrade
journal, July 2005


The effects of impurities and core pressure on pedestal stability in Joint European Torus (JET)a)
journal, May 2015

  • Saarelma, S.; Järvinen, A.; Beurskens, M.
  • Physics of Plasmas, Vol. 22, Issue 5
  • DOI: 10.1063/1.4921413

Off-diagonal particle and toroidal momentum transport: a survey of experimental, theoretical and modelling aspects
journal, October 2012


Correlation theory of a two‐dimensional plasma turbulence with shear flow
journal, July 1993

  • Zhang, Y. Z.; Mahajan, S. M.
  • Physics of Fluids B: Plasma Physics, Vol. 5, Issue 7
  • DOI: 10.1063/1.860788

Kinetic neoclassical transport in the H-mode pedestal
journal, July 2014

  • Battaglia, D. J.; Burrell, K. H.; Chang, C. S.
  • Physics of Plasmas, Vol. 21, Issue 7
  • DOI: 10.1063/1.4886803

The global version of the gyrokinetic turbulence code GENE
journal, August 2011

  • Görler, T.; Lapillonne, X.; Brunner, S.
  • Journal of Computational Physics, Vol. 230, Issue 18
  • DOI: 10.1016/j.jcp.2011.05.034

Observation of Edge Instability Limiting the Pedestal Growth in Tokamak Plasmas
journal, March 2014


Field‐aligned coordinates for nonlinear simulations of tokamak turbulence
journal, August 1995

  • Beer, M. A.; Cowley, S. C.; Hammett, G. W.
  • Physics of Plasmas, Vol. 2, Issue 7
  • DOI: 10.1063/1.871232

Microtearing turbulence limiting the JET-ILW pedestal
journal, August 2016


Pedestal transport in H-mode plasmas for fusion gain
journal, April 2017


MHD and gyro-kinetic stability of JET pedestals
journal, November 2013


Pedestal stability comparison and ITER pedestal prediction
journal, July 2009


Intermediate- k density and magnetic field fluctuations during inter-ELM pedestal evolution in MAST
journal, November 2015


Gyrokinetic projection of the divertor heat-flux width from present tokamaks to ITER
journal, August 2017


Gyrokinetic turbulence under near-separatrix or nonaxisymmetric conditions
journal, May 2009

  • Jenko, F.; Told, D.; Xanthopoulos, P.
  • Physics of Plasmas, Vol. 16, Issue 5
  • DOI: 10.1063/1.3089603

Investigation of inter-ELM ion heat transport in the H-mode pedestal of ASDEX Upgrade plasmas
journal, October 2016


Gyrokinetic microinstabilities in ASDEX Upgrade edge plasmas
journal, October 2008

  • Told, D.; Jenko, F.; Xanthopoulos, P.
  • Physics of Plasmas, Vol. 15, Issue 10
  • DOI: 10.1063/1.3000132

A gyrokinetic perspective on the JET-ILW pedestal
journal, January 2017


SOLPS modelling of ASDEX upgrade H-mode plasma
journal, May 2006


Analysis of pedestal plasma transport
journal, May 2010


System Size Effects on Gyrokinetic Turbulence
journal, October 2010


Active spectroscopy measurements of the deuterium temperature, rotation, and density from the core to scrape off layer on the DIII-D tokamak (invited)
journal, October 2018

  • Haskey, S. R.; Grierson, B. A.; Stagner, L.
  • Review of Scientific Instruments, Vol. 89, Issue 10
  • DOI: 10.1063/1.5038349

Impact of wall materials and seeding gases on the pedestal and on core plasma performance
journal, August 2017


Edge turbulence scaling with shear flow
journal, June 1992

  • Zhang, Y. Z.; Mahajan, S. M.
  • Physics of Fluids B: Plasma Physics, Vol. 4, Issue 6
  • DOI: 10.1063/1.860095

    Works referencing / citing this record:

    Overview of the JET ITER-like Wall Project
    journal, December 2010


    The global version of the gyrokinetic turbulence code GENE
    journal, August 2011

    • Görler, T.; Lapillonne, X.; Brunner, S.
    • Journal of Computational Physics, Vol. 230, Issue 18
    • DOI: 10.1016/j.jcp.2011.05.034

    Impact of wall materials and seeding gases on the pedestal and on core plasma performance
    journal, August 2017


    Gyrokinetic microinstabilities in ASDEX Upgrade edge plasmas
    journal, October 2008

    • Told, D.; Jenko, F.; Xanthopoulos, P.
    • Physics of Plasmas, Vol. 15, Issue 10
    • DOI: 10.1063/1.3000132

    Gyrokinetic turbulence under near-separatrix or nonaxisymmetric conditions
    journal, May 2009

    • Jenko, F.; Told, D.; Xanthopoulos, P.
    • Physics of Plasmas, Vol. 16, Issue 5
    • DOI: 10.1063/1.3089603

    Development and validation of a predictive model for the pedestal height
    journal, May 2009

    • Snyder, P. B.; Groebner, R. J.; Leonard, A. W.
    • Physics of Plasmas, Vol. 16, Issue 5
    • DOI: 10.1063/1.3122146

    Particle pinch and collisionality in gyrokinetic simulations of tokamak plasma turbulence
    journal, June 2009

    • Angioni, C.; Candy, J.; Fable, E.
    • Physics of Plasmas, Vol. 16, Issue 6
    • DOI: 10.1063/1.3155498

    Flux- and gradient-driven global gyrokinetic simulation of tokamak turbulence
    journal, May 2011

    • Görler, Tobias; Lapillonne, Xavier; Brunner, Stephan
    • Physics of Plasmas, Vol. 18, Issue 5
    • DOI: 10.1063/1.3567484

    Kinetic neoclassical transport in the H-mode pedestal
    journal, July 2014

    • Battaglia, D. J.; Burrell, K. H.; Chang, C. S.
    • Physics of Plasmas, Vol. 21, Issue 7
    • DOI: 10.1063/1.4886803

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

    • Diallo, A.; Groebner, R. J.; Rhodes, T. L.
    • Physics of Plasmas, Vol. 22, Issue 5
    • DOI: 10.1063/1.4921148

    The effects of impurities and core pressure on pedestal stability in Joint European Torus (JET)a)
    journal, May 2015

    • Saarelma, S.; Järvinen, A.; Beurskens, M.
    • Physics of Plasmas, Vol. 22, Issue 5
    • DOI: 10.1063/1.4921413

    Active spectroscopy measurements of the deuterium temperature, rotation, and density from the core to scrape off layer on the DIII-D tokamak (invited)
    journal, October 2018

    • Haskey, S. R.; Grierson, B. A.; Stagner, L.
    • Review of Scientific Instruments, Vol. 89, Issue 10
    • DOI: 10.1063/1.5038349

    Edge turbulence scaling with shear flow
    journal, June 1992

    • Zhang, Y. Z.; Mahajan, S. M.
    • Physics of Fluids B: Plasma Physics, Vol. 4, Issue 6
    • DOI: 10.1063/1.860095

    Correlation theory of a two‐dimensional plasma turbulence with shear flow
    journal, July 1993

    • Zhang, Y. Z.; Mahajan, S. M.
    • Physics of Fluids B: Plasma Physics, Vol. 5, Issue 7
    • DOI: 10.1063/1.860788

    Field‐aligned coordinates for nonlinear simulations of tokamak turbulence
    journal, August 1995

    • Beer, M. A.; Cowley, S. C.; Hammett, G. W.
    • Physics of Plasmas, Vol. 2, Issue 7
    • DOI: 10.1063/1.871232

    Electron temperature gradient driven turbulence
    journal, May 2000

    • Jenko, F.; Dorland, W.; Kotschenreuther, M.
    • Physics of Plasmas, Vol. 7, Issue 5
    • DOI: 10.1063/1.874014

    Scaling laws for edge plasma parameters in ITER from two-dimensional edge modelling
    journal, August 2003


    Characterization of the H-mode edge barrier at ASDEX Upgrade
    journal, July 2005


    Pedestal stability comparison and ITER pedestal prediction
    journal, July 2009


    Analysis of pedestal plasma transport
    journal, May 2010


    Simulations of density profiles, pellet fuelling and density control in ITER
    journal, November 2011


    Off-diagonal particle and toroidal momentum transport: a survey of experimental, theoretical and modelling aspects
    journal, October 2012


    Edge microstability of NSTX plasmas without and with lithium-coated plasma-facing components
    journal, September 2013


    Impact of nitrogen seeding on confinement and power load control of a high-triangularity JET ELMy H-mode plasma with a metal wall
    journal, September 2013


    MHD and gyro-kinetic stability of JET pedestals
    journal, November 2013


    High-accuracy characterization of the edge radial electric field at ASDEX Upgrade
    journal, April 2013


    Confinement and edge studies towards low ρ * and ν * at JET
    journal, June 2013


    First scenario development with the JET new ITER-like wall
    journal, December 2013


    The H-mode pedestal structure and its role on confinement in JET with a carbon and metal wall
    journal, December 2014


    Pedestal confinement and stability in JET-ILW ELMy H-modes
    journal, September 2015


    Gyrokinetic study of ASDEX Upgrade inter-ELM pedestal profile evolution
    journal, May 2015


    Microtearing turbulence limiting the JET-ILW pedestal
    journal, August 2016


    Investigation of inter-ELM ion heat transport in the H-mode pedestal of ASDEX Upgrade plasmas
    journal, October 2016


    Washboard modes as ELM-related events in JET
    journal, November 2003

    • Perez, C. P.; Koslowski, H. R.; Hender, T. C.
    • Plasma Physics and Controlled Fusion, Vol. 46, Issue 1
    • DOI: 10.1088/0741-3335/46/1/005

    SOLPS modelling of ASDEX upgrade H-mode plasma
    journal, May 2006


    Effects of impurities on electron temperature gradient modes
    journal, September 2008


    Local and global Fokker–Planck neoclassical calculations showing flow and bootstrap current modification in a pedestal
    journal, October 2012


    Progress at JET in integrating ITER-relevant core and edge plasmas within the constraints of an ITER-like wall
    journal, February 2015


    Intermediate- k density and magnetic field fluctuations during inter-ELM pedestal evolution in MAST
    journal, November 2015


    Plasma confinement at JET
    journal, December 2015


    High frequency magnetic fluctuations correlated with the inter-ELM pedestal evolution in ASDEX Upgrade
    journal, May 2016


    The response of toroidal drift modes to profile evolution: a model for small-ELMs in tokamak plasmas?
    journal, June 2016


    Dimensionless scalings of confinement, heat transport and pedestal stability in JET-ILW and comparison with JET-C
    journal, October 2016


    Non-local effects on pedestal kinetic ballooning mode stability
    journal, April 2017

    • Saarelma, S.; Martin-Collar, J.; Dickinson, D.
    • Plasma Physics and Controlled Fusion, Vol. 59, Issue 6
    • DOI: 10.1088/1361-6587/aa66ab

    Analysis of ELM stability with extended MHD models in JET, JT-60U and future JT-60SA tokamak plasmas
    journal, November 2017


    Flow shear suppression of pedestal ion temperature gradient turbulence-A first principles theoretical framework
    journal, June 2018

    • Hatch, D. R.; Hazeltine, R. D.; Kotschenreuther, M. K.
    • Plasma Physics and Controlled Fusion, Vol. 60, Issue 8
    • DOI: 10.1088/1361-6587/aac7a7

    Main ion and impurity edge profile evolution across the L- to H-mode transition on DIII-D
    journal, August 2018

    • Haskey, S. R.; Grierson, B. A.; Chrystal, C.
    • Plasma Physics and Controlled Fusion, Vol. 60, Issue 10
    • DOI: 10.1088/1361-6587/aad702

    A gyrokinetic perspective on the JET-ILW pedestal
    journal, January 2017


    Overview of the JET results in support to ITER
    journal, June 2017


    Pedestal transport in H-mode plasmas for fusion gain
    journal, April 2017


    Studies of the pedestal structure and inter-ELM pedestal evolution in JET with the ITER-like wall
    journal, August 2017


    Gyrokinetic projection of the divertor heat-flux width from present tokamaks to ITER
    journal, August 2017


    Pedestal evolution physics in low triangularity JET tokamak discharges with ITER-like wall
    journal, November 2017