UEDGE simulation of edge plasmas in DIII-D double null configurations

Journal Article · Mon Nov 15 00:00:00 EST 2010 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3499666· OSTI ID:21531977

Porter, G D; Rognlien, T D; Rensink, M E ^[1]; Petrie, T W ^[2]

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1. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
2. General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)

Analysis of plasma flow in the edge of double null hybrid mode DIII-D plasmas is reported. The two dimension fluid plasma code UEDGE [T. Rognlien et al., J. Nucl. Mater. 196-198, 347 (1992)] is used for the analysis. The effect of impurity radiation from intrinsic carbon sputtered from plasma facing surfaces is included as is the effect of plasma drifts. Two discharges in which the flux surfaces through the poloidal field nulls (X-points) are separated by 1 cm at the outer midplane are analyzed. The discharges differ only in the direction of the ion {nabla}B drift. It is shown that the flow of both primary ions and intrinsic impurities is dominated by the effect of plasma drifts. Variations in the recycling of deuterium ions, as seen in D{sub {alpha}} emission profiles, are qualitatively consistent with experiment and are driven by the effect of ExB drifts associated with radial gradients of the electron temperature at the secondary separatrix. Trace argon impurity is introduced to simulate the transport of argon used in the experiment to enhance divertor radiation power. Penetration of the trace argon to the closed field lines depends on the direction of the ion {nabla}B drift, consistent with experiment. The analysis described here includes the effect of a deuterium gas puff to establish the ''puff and pump'' configuration. The poloidal flow of impurities is a balance between the projection of the parallel flow and poloidal drifts, primarily from ExB. It is shown that the effect of the gas puff is primarily to alter the electron temperature profile and thus affects impurity flow via alteration of ExB drifts, not via entrainment in deuterium ion parallel flow.

• OSTI ID: 21531977
• Journal Information: Physics of Plasmas, Vol. 17, Issue 11; Other Information: DOI: 10.1063/1.3499666; (c) 2010 American Institute of Physics; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BOUNDARY LAYERS
DEUTERIUM IONS
DOUBLET-3 DEVICE
ELECTROMAGNETIC FIELDS
ELECTRON TEMPERATURE
FIRST WALL
MAGNETIC SURFACES
PLASMA
PLASMA DRIFT
PLASMA IMPURITIES
PLASMA SIMULATION
CHARGED PARTICLES
CLOSED PLASMA DEVICES
IMPURITIES
IONS
LAYERS
MAGNETIC FIELD CONFIGURATIONS
SIMULATION
THERMONUCLEAR DEVICES
THERMONUCLEAR REACTOR WALLS
TOKAMAK DEVICES