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Title: Gyrokinetic analysis and simulation of pedestals to identify the culprits for energy losses using ‘fingerprints’

Journal Article · · Nuclear Fusion

Fusion performance in tokamaks hinges critically on the efficacy of the edge transport barrier (ETB) in suppressing energy losses. The new concept of 'fingerprints' is introduced to identify the instabilities that cause transport losses in the ETBs of many of today's experiments, from among widely posited candidates. Analysis of the gyrokinetic-Maxwell equations and gyrokinetic simulations of experiments reveals that each mode type produces characteristic ratios of transport in the various channels: density, heat, and impurities. This, together with experimental observations of transport in some channel or of the relative size of the driving sources of channels, can identify or determine the dominant modes causing energy transport. In multiple H-mode cases with edge-localized modes that are examined, these fingerprints indicate that magnetohydrodynamic (MHD)-like modes are apparently not the dominant agent of energy transport; rather, this role is played by micro-tearing modes (MTMs) and electron temperature gradient (ETG) modes, and furthermore, possibly by ion temperature gradient/trapped electron modes (ITG/TEM) on JET (Joint European Torus). MHD-like modes may dominate the electron particle losses. Fluctuation frequency can also be a vital means of identification, and is often closely related to the transport fingerprint. The analytical arguments unify and explain previously disparate experimental observations on multiple devices, including DIII-D, JET, and ASDEX-U. Detailed simulations of two DIII-D ETBs also demonstrate and corroborate this.

Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC); Princeton Univ., NJ (United States); General Atomics, San Diego, CA (United States); Univ. of Texas, Austin, TX (United States)
Sponsoring Organization:
USDOE Office of Science (SC)
Contributing Organization:
the DIII-D TEAM; JET Contributors
Grant/Contract Number:
AC02-09CH11466; FC02-04ER54698; FG02-04ER54742
OSTI ID:
1577624
Journal Information:
Nuclear Fusion, Vol. 59, Issue 9; ISSN 0029-5515
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 68 works
Citation information provided by
Web of Science

References (70)

Unified theory of tearing modes journal January 1979
Validating a quasi-linear transport model versus nonlinear simulations journal July 2009
Radial impurity transport in the H mode transport barrier region in Alcator C-Mod journal October 2000
Kinetic Instabilities that Limit β in the Edge of a Tokamak Plasma: A Picture of an H -Mode Pedestal journal March 2012
Overview of the JET results in support to ITER journal June 2017
Stabilization of the tearing mode in high-temperature plasma journal January 1983
Destabilization of global Alfvén eigenmodes and kinetic Alfvén waves by alpha particles in a tokamak plasma journal January 1987
Kinetic theory of tearing instability journal January 1975
Gyrokinetic study of ASDEX Upgrade inter-ELM pedestal profile evolution journal May 2015
Increase of turbulence and transport with resonant magnetic perturbations in ELM-suppressed plasmas on DIII-D journal September 2013
Ion viscosity stabilization of resistive internal kink modes journal January 1986
Correlations between quasi-coherent fluctuations and the pedestal evolution during the inter-edge localized modes phase on DIII-Da) journal May 2015
Kinetic theory of tearing instabilities journal January 1977
Kinetic theory of resistive ballooning modes journal January 1985
Gyrokinetic simulation of dissipative trapped electron mode in tokamak edge journal May 2017
Electron Temperature Gradient Turbulence journal December 2000
Global Gyrokinetic Simulation of Tokamak Edge Pedestal Instabilities journal November 2012
Quasi-coherent fluctuations limiting the pedestal growth on Alcator C-Mod: experiment and modelling journal April 2015
Global gyrokinetic simulations of the H-mode tokamak edge pedestal journal May 2013
High frequency magnetic fluctuations correlated with the inter-ELM pedestal evolution in ASDEX Upgrade journal May 2016
Attaining neoclassical transport in ignited tokamaks journal March 2000
Edge microstability of NSTX plasmas without and with lithium-coated plasma-facing components journal September 2013
Recursive derivation of drift-kinetic equation journal January 1973
Comparison of initial value and eigenvalue codes for kinetic toroidal plasma instabilities journal August 1995
Modelling of transitions between L- and H-mode in JET high plasma current plasmas and application to ITER scenarios including tungsten behaviour journal June 2017
Flow shear suppression of pedestal ion temperature gradient turbulence-A first principles theoretical framework journal June 2018
Edge energy transport barrier and turbulence in the I-mode regime on Alcator C-Mod journal May 2011
Effects of E×B velocity shear and magnetic shear on turbulence and transport in magnetic confinement devices journal May 1997
Washboard modes as ELM-related events in JET journal November 2003
ELM flushing and impurity transport in the H-mode edge barrier in ASDEX Upgrade journal August 2011
Core turbulent transport in tokamak plasmas: bridging theory and experiment with QuaLiKiz journal December 2015
Pedestal Bifurcation and Resonant Field Penetration at the Threshold of Edge-Localized Mode Suppression in the DIII-D Tokamak journal March 2015
Characterization of the H-mode edge barrier at ASDEX Upgrade journal July 2005
Erratum: ‘‘A four-field model for tokamak plasma dynamics’’ [Phys. Fluids 28, 2466 (1985)] journal January 1986
Towards the construction of a model to describe the inter-ELM evolution of the pedestal on MAST journal October 2011
Correlation theory of a two‐dimensional plasma turbulence with shear flow journal July 1993
Flow shear induced fluctuation suppression in finite aspect ratio shaped tokamak plasma journal May 1995
A first-principles predictive model of the pedestal height and width: development, testing and ITER optimization with the EPED model journal August 2011
Observation of Edge Instability Limiting the Pedestal Growth in Tokamak Plasmas journal March 2014
Microtearing turbulence limiting the JET-ILW pedestal journal August 2016
Pedestal transport in H-mode plasmas for fusion gain journal April 2017
Measurements of ion temperature fluctuations in the Tokamak Fusion Test Reactor journal February 1998
Inter-ELM evolution of the edge current density in JET-ILW type I ELMy H-mode plasmas journal June 2018
Pedestal stability comparison and ITER pedestal prediction journal July 2009
MHD and gyro-kinetic stability of JET pedestals journal November 2013
On broken ballooning symmetry journal July 1991
Advances in understanding quiescent H-mode plasmas in DIII-D journal May 2005
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
Violating Suydam criterion produces feeble instabilities journal August 2002
Heat and particle transport in a tokamak: advances in nonlinear gyrokinetics journal November 2005
Pedestal and edge electrostatic turbulence characteristics from an XGC1 gyrokinetic simulation journal August 2017
A quarter-century of H-mode studies journal November 2007
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
High Mode Number Stability of an Axisymmetric Toroidal Plasma
  • Connor, J. W.; Hastie, R. J.; Taylor, J. B.
  • Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 365, Issue 1720 https://doi.org/10.1098/rspa.1979.0001
journal February 1979
ITER predictions using the GYRO verified and experimentally validated trapped gyro-Landau fluid transport model journal June 2011
A gyrokinetic perspective on the JET-ILW pedestal journal January 2017
SOLPS modelling of ASDEX upgrade H-mode plasma journal May 2006
High-n ideal and resistive shear Alfvén waves in tokamaks journal April 1985
Analysis of pedestal plasma transport journal May 2010
A theory-based transport model with comprehensive physics journal May 2007
Microtearing modes at the top of the pedestal journal June 2013
Resistive ballooning modes journal January 1981
Towards the construction of a model to describe the inter-ELM evolution of the pedestal on MAST text January 2011
Global Gyrokinetic Simulation of Tokamak Edge Pedestal Instabilities text January 2012
Microtearing modes at the top of the pedestal text January 2012
MHD and Gyro-kinetic Stability of JET Pedestals text January 2013
Gyrokinetic projection of the divertor heat-flux width from present tokamaks to ITER text January 2017

Cited By (2)

Experimental observation of coexisting electromagnetic fluctuations correlating with the inter-ELM pedestal evolution on EAST journal December 2019
Dynamics of the pedestal transport during edge localized mode cycles at ASDEX Upgrade journal January 2020

Figures / Tables (31)