Advances in validating gyrokinetic turbulence models against L- and H-mode plasmas

Journal Article · Sun May 15 04:00:00 EDT 2011 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3574518· OSTI ID:21537876

Holland, C ^[1]; Schmitz, L; Rhodes, T L; Peebles, W A; Hillesheim, J C; Wang, G; Zeng, L; Doyle, E J ^[2]; Smith, S P; Prater, R; Burrell, K H; Candy, J; Waltz, R E; Kinsey, J E; Staebler, G M; DeBoo, J C; Petty, C C ^[3]; McKee, G R; Yan, Z ^[4]; White, A E ^[5]

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1. University of California-San Diego, 9500 Gilman Drive, La Jolla, California 92093-0417 (United States)
2. University of California-Los Angeles, PO Box 957099, Los Angeles, California 90095-7099 (United States)
3. General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States)
4. University of Wisconsin-Madison, 1500 Engineering Dr., Madison, Wisconsin 53706 (United States)
5. Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139 (United States)

Robust validation of predictive turbulent transport models requires quantitative comparisons to experimental measurements at multiple levels, over a range of physically relevant conditions. Toward this end, a series of carefully designed validation experiments has been performed on the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] to obtain comprehensive multifield, multipoint, multiwavenumber fluctuation measurements and their scalings with key dimensionless parameters. The results of two representative validation studies are presented: an elongation scaling study performed in beam heated L-mode discharges and an electron heating power scan performed in quiescent H-mode (QH-mode) discharges. A 50% increase in the elongation {kappa} is observed to lead to a {approx}50% increase in energy confinement time {tau}{sub e} and accompanying decrease in fluctuation levels, qualitatively consistent with a priori theoretical predictions and nonlinear GYRO [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] simulations. However, these simulations exhibit clear quantitative differences from experiment in the predicted magnitudes and trends with radius of turbulent fluxes and fluctuation levels which cannot be fully accounted for by uncertainties due to transport stiffness. In the QH-mode study, local nonlinear GYRO simulations that neglect fast ion effects show a similar proportional response to the applied electron cyclotron heating as the experiment, but overpredict the magnitudes of transport and fluctuation levels by a factor of 10 or more. Possible sources of this overprediction, namely nonlocal effects and self-consistent fast beam ions, are identified and discussed.

• OSTI ID: 21537876
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 18; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CLOSED PLASMA DEVICES
CONFINEMENT
DOUBLET-3 DEVICE
FLUCTUATIONS
H-MODE PLASMA CONFINEMENT
L-MODE PLASMA CONFINEMENT
MAGNETIC CONFINEMENT
NONLINEAR PROBLEMS
PLASMA CONFINEMENT
PLASMA SIMULATION
SIMULATION
TESTING
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TURBULENCE
VALIDATION
VARIATIONS