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Title: Quantitative comparison of electron temperature fluctuations to nonlinear gyrokinetic simulations in C-Mod Ohmic L-mode discharges

Abstract

Long wavelength turbulent electron temperature fluctuations (kyρs < 0.3) are measured in the outer core region (r/a > 0.8) of Ohmic L-mode plasmas at Alcator C-Mod [E. S. Marmar et al., Nucl. Fusion 49, 104014 (2009)] with a correlation electron cyclotron emission diagnostic. The relative amplitude and frequency spectrum of the fluctuations are compared quantitatively with nonlinear gyrokinetic simulations using the GYRO code [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] in two different confinement regimes: linear Ohmic confinement (LOC) regime and saturated Ohmic confinement (SOC) regime. When comparing experiment with nonlinear simulations, it is found that local, electrostatic ion-scale simulations (kyρs ≲ 1.7) performed at r/a ~ 0.85 reproduce the experimental ion heat flux levels, electron temperature fluctuation levels, and frequency spectra within experimental error bars. On the other hand, the electron heat flux is robustly under-predicted and cannot be recovered by using scans of the simulation inputs within error bars or by using global simulations. If both the ion heat flux and the measured temperature fluctuations are attributed predominantly to long-wavelength turbulence, then under-prediction of electron heat flux strongly suggests that electron scale turbulence is important for transport in C-Mod Ohmic L-mode discharges. Furthermore,more » no evidence is found from linear or nonlinear simulations for a clear transition from trapped electron mode to ion temperature gradient turbulence across the LOC/SOC transition, and also there is no evidence in these Ohmic L-mode plasmas of the “Transport Shortfall” [C. Holland et al., Phys. Plasmas 16, 052301 (2009)].« less

Authors:
 [1];  [2]; ORCiD logo [3]; ORCiD logo [2];  [4];  [2];  [3];  [5]
  1. University of California, Los Angeles, Los Angeles, California 90095, USA
  2. Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
  3. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
  4. University of California, San Diego, La Jolla, California 92093, USA
  5. Ecole Polytechnique Fédérale de Lausanne, SPC, Lausanne 1015, Switzerland
Publication Date:
Research Org.:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES); National Energy Research Scientific Computing Center (NERSC)
Contributing Org.:
Alcator C-Mod Team
OSTI Identifier:
1547042
Alternate Identifier(s):
OSTI ID: 1246539
Grant/Contract Number:  
SC0006419; FC02-99ER54512; AC02-05CH11231; SC006419
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 23; Journal Issue: 4; 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

Sung, C., White, A. E., Mikkelsen, D. R., Greenwald, M., Holland, C., Howard, N. T., Churchill, R., and Theiler, C. Quantitative comparison of electron temperature fluctuations to nonlinear gyrokinetic simulations in C-Mod Ohmic L-mode discharges. United States: N. p., 2016. Web. doi:10.1063/1.4945620.
Sung, C., White, A. E., Mikkelsen, D. R., Greenwald, M., Holland, C., Howard, N. T., Churchill, R., & Theiler, C. Quantitative comparison of electron temperature fluctuations to nonlinear gyrokinetic simulations in C-Mod Ohmic L-mode discharges. United States. https://doi.org/10.1063/1.4945620
Sung, C., White, A. E., Mikkelsen, D. R., Greenwald, M., Holland, C., Howard, N. T., Churchill, R., and Theiler, C. 2016. "Quantitative comparison of electron temperature fluctuations to nonlinear gyrokinetic simulations in C-Mod Ohmic L-mode discharges". United States. https://doi.org/10.1063/1.4945620. https://www.osti.gov/servlets/purl/1547042.
@article{osti_1547042,
title = {Quantitative comparison of electron temperature fluctuations to nonlinear gyrokinetic simulations in C-Mod Ohmic L-mode discharges},
author = {Sung, C. and White, A. E. and Mikkelsen, D. R. and Greenwald, M. and Holland, C. and Howard, N. T. and Churchill, R. and Theiler, C.},
abstractNote = {Long wavelength turbulent electron temperature fluctuations (kyρs < 0.3) are measured in the outer core region (r/a > 0.8) of Ohmic L-mode plasmas at Alcator C-Mod [E. S. Marmar et al., Nucl. Fusion 49, 104014 (2009)] with a correlation electron cyclotron emission diagnostic. The relative amplitude and frequency spectrum of the fluctuations are compared quantitatively with nonlinear gyrokinetic simulations using the GYRO code [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] in two different confinement regimes: linear Ohmic confinement (LOC) regime and saturated Ohmic confinement (SOC) regime. When comparing experiment with nonlinear simulations, it is found that local, electrostatic ion-scale simulations (kyρs ≲ 1.7) performed at r/a ~ 0.85 reproduce the experimental ion heat flux levels, electron temperature fluctuation levels, and frequency spectra within experimental error bars. On the other hand, the electron heat flux is robustly under-predicted and cannot be recovered by using scans of the simulation inputs within error bars or by using global simulations. If both the ion heat flux and the measured temperature fluctuations are attributed predominantly to long-wavelength turbulence, then under-prediction of electron heat flux strongly suggests that electron scale turbulence is important for transport in C-Mod Ohmic L-mode discharges. Furthermore, no evidence is found from linear or nonlinear simulations for a clear transition from trapped electron mode to ion temperature gradient turbulence across the LOC/SOC transition, and also there is no evidence in these Ohmic L-mode plasmas of the “Transport Shortfall” [C. Holland et al., Phys. Plasmas 16, 052301 (2009)].},
doi = {10.1063/1.4945620},
url = {https://www.osti.gov/biblio/1547042}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 4,
volume = 23,
place = {United States},
year = {Fri Apr 08 00:00:00 EDT 2016},
month = {Fri Apr 08 00:00:00 EDT 2016}
}

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Works referenced in this record:

Reconstruction of current profile parameters and plasma shapes in tokamaks
journal, November 1985


An Eulerian gyrokinetic-Maxwell solver
journal, April 2003


Measurement of electron temperature fluctuations using a tunable correlation electron cyclotron emission system on Alcator C-Mod
journal, November 2014


Density impact on toroidal rotation in Tore Supra: experimental observations and theoretical investigation
journal, February 2015


Turbulence and energy confinement in TORE SUPRA Ohmic discharges
journal, December 1992


Calculation of impurity poloidal rotation from measured poloidal asymmetries in the toroidal rotation of a tokamak plasma
journal, October 2012


Impurity-induced turbulence suppression and reduced transport in the DIII-D tokamak
journal, May 2000


Intrinsic Toroidal Rotation, Density Peaking, and Turbulence Regimes in the Core of Tokamak Plasmas
journal, November 2011


Electron temperature gradient driven turbulence
journal, May 2000


Transport analysis of ohmic, L-mode and improved confinement discharges in FTU
journal, September 2004


Measurements of the deuterium ion toroidal rotation in the DIII-D tokamak and comparison to neoclassical theory
journal, May 2012


Critical gradient formula for toroidal electron temperature gradient modes
journal, September 2001


A flux-matched gyrokinetic analysis of DIII-D L-mode turbulence
journal, December 2014


Synergistic cross-scale coupling of turbulence in a tokamak plasma
journal, November 2014


Observations of core toroidal rotation reversals in Alcator C-Mod ohmic L-mode plasmas
journal, June 2011


Edge radial electric field structure and its connections to H-mode confinement in Alcator C-Mod plasmas
journal, May 2009


Poloidal asymmetries in edge transport barriersa)
journal, May 2015


Search for the ion temperature gradient mode in a tokamak plasma and comparison with theoretical predictions
journal, May 2001


System for simulating fluctuation diagnostics for application to turbulence computations
journal, January 2006


Electron Temperature Gradient Turbulence
journal, December 2000


Design of a correlation electron cyclotron emission diagnostic for Alcator C-Mod
journal, October 2012


Survey of theories of anomalous transport
journal, May 1994


Quasi-coherent modes and electron-driven turbulence
journal, November 2014


A review of experimental drift turbulence studies
journal, October 2009


Ohmic energy confinement saturation and core toroidal rotation reversal in Alcator C-Mod plasmas
journal, May 2012


Identification of trapped electron modes in frequency fluctuation spectra
journal, November 2015


Transport in toroidal devices-the experimentalist's view
journal, October 1993


Toroidal semicollisional microinstabilities and anomalous electron and ion transport
journal, April 1990


Overview of the Alcator C-Mod Research Program
journal, September 2009


Transport and turbulence studies in the linear ohmic confinement regime in Alcator C-Mod
journal, November 2012


Comparison of BES measurements of ion-scale turbulence with direct gyro-kinetic simulations of MAST L-mode plasmas
journal, January 2014


Turbulence in the TORE SUPRA Tokamak: Measurements and Validation of Nonlinear Simulations
journal, April 2009


Fidelity of reduced and realistic electron mass ratio multi-scale gyrokinetic simulations of tokamak discharges
journal, April 2015


Core intrinsic rotation behaviour in ASDEX Upgrade ohmic L-mode plasmas
journal, March 2014


Investigation of the transport shortfall in Alcator C-Mod L-mode plasmas
journal, March 2013


Core temperature fluctuations and related heat transport in the Texas Experimental Tokamak‐Upgrade
journal, March 1995


Energy confinement and high-k turbulence on HT-7 tokamak
journal, June 2008


Non-local heat transport in Alcator C-Mod ohmic L-mode plasmas
journal, June 2014


Gyrokinetic theory of slab electron temperature gradient mode in negative shear tokamaks
journal, June 2000


Bootstrap current and neoclassical transport in tokamaks of arbitrary collisionality and aspect ratio
journal, September 1997


Noncircular, finite aspect ratio, local equilibrium model
journal, April 1998


Experimental test of the neoclassical theory of impurity poloidal rotation in tokamaks
journal, May 2006


Characterizing turbulent transport in ASDEX Upgrade L-mode plasmas via nonlinear gyrokinetic simulations
journal, December 2013


Implementation and application of two synthetic diagnostics for validating simulations of core tokamak turbulence
journal, May 2009


Recent results and prospects for correlation ECE measurements on TCV
journal, January 2012


Works referencing / citing this record:

VITALS: A Surrogate-Based Optimization Framework for the Accelerated Validation of Plasma Transport Codes
journal, February 2018


Multi-scale gyrokinetic simulations of an Alcator C-Mod, ELM-y H-mode plasma
journal, November 2017


Hysteresis as a probe of turbulent bifurcation in intrinsic rotation reversals on Alcator C-Mod
journal, August 2019