Probing plasma turbulence by modulating the electron temperature gradient

Journal Article · Sat May 15 00:00:00 EDT 2010 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3316298· OSTI ID:21371190

DeBoo, J C; Petty, C C ^[1]; Holland, C ^[2]; Rhodes, T L; Schmitz, L; Wang, G; Doyle, E J; Hillesheim, J; Peebles, W A; Zeng, L ^[3]; White, A E ^[4]; Austin, M E ^[5]; Yan, Z ^[6]

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1. General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)
2. University of California-San Diego, 9500 Gilman Drive, La Jolla, California 92093 (United States)
3. University of California-Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095 (United States)
4. Oak Ridge Institute for Science and Education, 130 Badger Avenue, Oak Ridge, Tennessee 37830-6218 (United States)
5. University of Texas-Austin, P.O. Box 8028, Austin, Texas 78713 (United States)
6. University of Wisconsin at Madison, 337 Engineering Research Building, 1500 Engineering Drive, Madison, Wisconsin 53706 (United States)

The local value of a/L{sub Te}, a turbulence drive term, was modulated with electron cyclotron heating in L-mode discharges on DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] and the density and electron temperature fluctuations in low, intermediate, and high-k regimes were measured and compared with nonlinear gyrokinetic turbulence simulations using the GYRO code [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)]. The local drive term at rhoapprox0.6 was reduced by up to 50%, which produced comparable reductions in electron temperature fluctuations at low-k. At intermediate k, k{sub t}hetaapprox4 cm{sup -1} and k{sub t}hetarho{sub s}approx0.8, a very interesting and unexpected result was observed where density fluctuations increased by up to 10% when the local drive term was decreased by 50%. Initial comparisons of simulations from GYRO with the thermal diffusivity from power balance analysis and measured turbulence response are reported. Simulations for the case with the lowest drive term are challenging as they are near the marginal value of a/L{sub Te} for trapped electron mode activity.

• OSTI ID: 21371190
• Journal Information: Physics of Plasmas, Vol. 17, Issue 5; Other Information: DOI: 10.1063/1.3316298; (c) 2010 American Institute of Physics; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DOUBLET-3 DEVICE
ECR HEATING
ELECTRIC DISCHARGES
ELECTRON TEMPERATURE
FLUCTUATIONS
L-MODE PLASMA CONFINEMENT
PLASMA
PLASMA DENSITY
PLASMA SIMULATION
TEMPERATURE GRADIENTS
THERMAL DIFFUSIVITY
TRAPPED ELECTRONS
TURBULENCE
CLOSED PLASMA DEVICES
CONFINEMENT
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
HEATING
HIGH-FREQUENCY HEATING
LEPTONS
MAGNETIC CONFINEMENT
PHYSICAL PROPERTIES
PLASMA CONFINEMENT
PLASMA HEATING
SIMULATION
THERMODYNAMIC PROPERTIES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
VARIATIONS