Probing plasma turbulence by modulating the electron temperature gradient
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White_Probing Plasma.pdf
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Author(s)
DeBoo, J. C.
Holland, C.
Rhodes, T. L.
Schmitz, L.
Wang, G.
White, Anne E.
Austin, M. E.
Doyle, E. J.
Hillesheim, J. C.
Peebles, W. A.
Date Issued
March 2010
Journal
Physics of Plasmas
Publisher
American Institute of Physics
Citation
DeBoo, J. C. et al. “Probing plasma turbulence by modulating the electron temperature gradient.” Physics of Plasmas 17 (2010): 056105. © 2010 American Institute of Physics.
Version
Final published version
Abstract
The local value of a/L[subscript 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 ρ ∼ 0.6 was reduced by up to 50%, which produced comparable reductions in electron temperature fluctuations at low-k. At intermediate k, ktheta ∼ 4 cm[superscript −1] and kthetaρs ∼ 0.8, 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[subscript Te] for trapped electron mode activity.
MIT Department
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
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DOI of Published Version
https://doi.org/10.1063/1.3316298
