Design and physics basis for the upcoming DIII-D SAS-VW campaign to quantify tungsten leakage and transport in a new slot divertor geometry

Abstract A set of experiments are planned to exploit the high SOL collisionality enabled by a tightly baffled slot divertor geometry to suppress tungsten leakage in DIII-D. A toroidal row of graphite tiles from the Small Angle Slot (SAS) divertor is being coated with 10–15 μ m of tungsten. New spect...

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Bibliographic Details
Published in:Physica scripta 2021-12, Vol.96 (12), p.124073
Main Authors: Abrams, T, Sinclair, G, Nichols, J H, Unterberg, E A, Donovan, D C, Duran, J, Elder, J D, Glass, F, Grierson, B A, Guo, H Y, Hall, T, Ma, X, Maurizio, R, McLean, A G, Murphy, C, Nguyen, R, Rudakov, D L, Stangeby, P C, Thomas, D M, Zamperini, S A
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DIII-D
divertors
DIVIMP
SOLPS
spectroscopy
tokamaks
tungsten
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Summary:Abstract A set of experiments are planned to exploit the high SOL collisionality enabled by a tightly baffled slot divertor geometry to suppress tungsten leakage in DIII-D. A toroidal row of graphite tiles from the Small Angle Slot (SAS) divertor is being coated with 10–15 μ m of tungsten. New spectroscopic viewing chords with in-vacuo optics will measure the W gross erosion source from the divertor surface with high spatial and temporal resolution. In parallel, the bottom of the SAS divertor is changed from a flat to a ‘V’ shape. New SOLPS-ITER/DIVIMP simulations conducted with drifts using the planned ‘V’ shape predict a substantial reduction in W sourcing and SOL accumulation in either B × ∇B direction relative to either the old SAS divertor shape or the open, lower divertor. Dedicated studies are planned to carefully characterize the level of W sourcing, leakage, and scrape-off-layer (SOL) accumulation in DIII-D over a wide range of plasma scenarios. Various actuators will be assessed for their efficacy in further reducing high-Z impurity sources and leakage from the slot divertor geometry. This coupled code-experiment validation effort will be used to stress-test physics models and build confidence in extrapolations to advanced, high-Z divertor geometries for next-step devices.
ISSN:0031-8949
1402-4896
DOI:10.1088/1402-4896/ac3c5f