Scrape-off layer transport and deposition studies in DIII-D

Journal Article · Tue May 15 04:00:00 EDT 2007 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2721978· OSTI ID:20975058

Groth, M; Allen, S L; Fenstermacher, M E; Lasnier, C J; Porter, G D; Rensink, M E; Rognlien, T D ^[1]; Boedo, J A; Rudakov, D L ^[2]; Brooks, N H; Groebner, R J; Leonard, A W; West, W P ^[3]; Elder, J D; McLean, A G; Lisgo, S; Stangeby, P C ^[4]; Wampler, W R; Watkins, J G ^[5]; Whyte, D G ^[6]

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1. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
2. University of California, San Diego, La Jolla, California 92093 (United States)
3. General Atomics, P.O. Box 85608, San Diego, California 92186 (United States)
4. University of Toronto Institute for Aerospace Studies, Toronto, Ontario M3H 5T6 (Canada)
5. Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)
6. Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

Trace {sup 13}CH{sub 4} injection experiments into the main scrape-off layer (SOL) of low density L-mode and high-density H-mode plasmas have been performed in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] to mimic the transport and deposition of carbon arising from a main chamber sputtering source. These experiments indicated entrainment of the injected carbon in plasma flow in the main SOL, and transport toward the inner divertor. Ex situ surface analysis showed enhanced {sup 13}C surface concentration at the corner formed by the divertor floor and the angled target plate of the inner divertor in L-mode; in H-mode high surface concentration was found both at the corner and along the surface bounding the private flux region inboard of the outer strike point. Interpretative modeling was made consistent with these experimental results by imposing a parallel carbon ion flow in the main SOL toward the inner target, and a radial pinch toward the separatrix. Predictive modeling carried out to better understand the underlying plasma transport processes suggests that the deuterium flow in the main SOL is related to the degree of detachment of the inner divertor leg. These simulations show that carbon ions are entrained with the deuteron flow in the main SOL via frictional coupling, but higher charge-state carbon ions may be suspended upstream of the inner divertor X-point region due to balance of the friction force and the ion temperature gradient force.

• OSTI ID: 20975058
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 14; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CARBON
CARBON 13
CARBON IONS
DEPOSITION
DEUTERIUM
DIVERTORS
DOUBLET-3 DEVICE
H-MODE PLASMA CONFINEMENT
L-MODE PLASMA CONFINEMENT
PLASMA
PLASMA SCRAPE-OFF LAYER
PLASMA SIMULATION
SURFACES