Predictions of the near edge transport shortfall in DIII-D L-mode plasmas using the trapped gyro-Landau-fluid model

Journal Article · Thu Jan 15 00:00:00 EST 2015 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4905630· OSTI ID:22408003

Kinsey, J. E. ^[1]; Staebler, G. M.; Candy, J.; Petty, C. C.; Waltz, R. E. ^[2]; Rhodes, T. L. ^[3]

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1. CompX, P.O. Box 2672, Del Mar, California 92014 (United States)
2. General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)
3. Physics Department and PSTI, University of California, Los Angeles, California 90095 (United States)

Previous studies of DIII-D L-mode plasmas have shown that a transport shortfall exists in that our current models of turbulent transport can significantly underestimate the energy transport in the near edge region. In this paper, the Trapped Gyro-Landau-Fluid (TGLF) drift wave transport model is used to simulate the near edge transport in a DIII-D L-mode experiment designed to explore the impact of varying the safety factor on the shortfall. We find that the shortfall systematically increases with increasing safety factor and is more pronounced for the electrons than for the ions. Within the shortfall dataset, a single high current case has been found where no transport shortfall is predicted. Reduced neutral beam injection power has been identified as the key parameter separating this discharge from other discharges exhibiting a shortfall. Further analysis shows that the energy transport in the L-mode near edge region is not stiff according to TGLF. Unlike the H-mode core region, the predicted temperature profiles are relatively more responsive to changes in auxiliary heating power. In testing the fidelity of TGLF for the near edge region, we find that a recalibration of the collision model is warranted. A recalibration improves agreement between TGLF and nonlinear gyrokinetic simulations performed using the GYRO code with electron-ion collisions. The recalibration only slightly impacts the predicted shortfall.

• OSTI ID: 22408003
• Journal Information: Physics of Plasmas, Vol. 22, Issue 1; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
AUXILIARY HEATING
BEAM INJECTION
COMPUTERIZED SIMULATION
DOUBLET-3 DEVICE
ELECTRON-ION COLLISIONS
ELECTRONS
ENERGY TRANSFER
H-MODE PLASMA CONFINEMENT
LANDAU DAMPING
L-MODE PLASMA CONFINEMENT
NONLINEAR PROBLEMS
TRANSPORT THEORY
WAVE PROPAGATION