Reduction of divertor carbon sources in DIII-D

The evolution of carbon release from the DIII-D lower divertor tiles is studied using atomic and molecular spectroscopy. Newly installed virgin graphite tiles in 1992 are found to have had a chemical erosion yield, Y chem⩽ 3–5%, consistent with both laboratory results and similar experiments in othe...

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Bibliographic Details
Published in:Journal of nuclear materials 2001-03, Vol.290, p.356-361
Main Authors: Whyte, D.G., West, W.P., Doerner, R., Brooks, N.H., Isler, R.C., Jackson, G.L., Porter, G., Wade, M.R., Wong, C.P.C.
Format: Article
Language:English
Subjects:
Carbon
Chemical erosion
Divertor
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Summary:The evolution of carbon release from the DIII-D lower divertor tiles is studied using atomic and molecular spectroscopy. Newly installed virgin graphite tiles in 1992 are found to have had a chemical erosion yield, Y chem⩽ 3–5%, consistent with both laboratory results and similar experiments in other totamaks. The average Y chem measured in the DIII-D lower divertor decreased approximately a factor of ten between 1992 and 2000. The presumed cause of this reduction is the cumulative effect of >30 wall-conditioning boronizations and 10 5 s of plasma exposure, although the relative importance of these two mechanisms is unknown. This result indicates that a substantial reduction in carbon chemical erosion, and its relative importance as a source of carbon, can be obtained by long-term in situ wall conditioning techniques. The total carbon source sputtered into the DIII-D lower divertor has also apparently decreased over the same period. However, there has been no significant decrease in the average core carbon contamination with the decreasing lower divertor carbon source.
ISSN:0022-3115
1873-4820
DOI:10.1016/S0022-3115(00)00497-9