Experimental studies of lithium-based surface chemistry for fusion plasma-facing materials applications

J. P. Allain, D. L. Rokusek, S. S. Harilal, M. Nieto-Perez, C. H. Skinner, H. W. Kugel, B. Heim, R. Kaita, R. Majeski

Research output: Contribution to journalArticle

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Abstract

Lithium has enhanced the operational performance of fusion devices such as: TFTR, CDX-U, FTU, T-11 M, and NSTX. Lithium in the solid and liquid state has been studied extensively in laboratory experiments including its erosion and hydrogen-retaining properties. Reductions in physical sputtering up to 40-60% have been measured for deuterated solid and liquid lithium surfaces. Computational modeling indicates that up to a 1:1 deuterium volumetric retention in lithium is possible. This paper presents the results of systematic in situ laboratory experimental studies on the surface chemistry evolution of ATJ graphite under lithium deposition. Results are compared to post-mortem analysis of similar lithium surface coatings on graphite exposed to deuterium discharge plasmas in NSTX. Lithium coatings on plasma-facing components in NSTX have shown substantial reduction of hydrogenic recycling. Questions remain on the role lithium surface chemistry on a graphite substrate has on particle sputtering (physical and chemical) as well as hydrogen isotope recycling. This is particularly due to the lack of in situ measurements of plasma-surface interactions in tokamaks such as NSTX. Results suggest that the lithium bonding state on ATJ graphite is lithium peroxide and with sufficient exposure to ambient air conditions, lithium carbonate is generated. Correlation between both results is used to assess the role of lithium chemistry on the state of lithium bonding and implications on hydrogen pumping and lithium sputtering. In addition, reduction of factors between 10 and 30 reduction in physical sputtering from lithiated graphite compared to pure lithium or carbon is also measured.

Original languageEnglish
Pages (from-to)942-946
Number of pages5
JournalJournal of Nuclear Materials
Volume390-391
Issue number1
DOIs
StatePublished - 15 Jun 2009
Externally publishedYes

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Facings
Surface chemistry
Lithium
Fusion reactions
lithium
fusion
chemistry
Plasmas
Graphite
graphite
Sputtering
sputtering
Hydrogen
Deuterium
recycling
Recycling
deuterium
Lithium Carbonate
liquid lithium
Coatings

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Allain, J. P. ; Rokusek, D. L. ; Harilal, S. S. ; Nieto-Perez, M. ; Skinner, C. H. ; Kugel, H. W. ; Heim, B. ; Kaita, R. ; Majeski, R. / Experimental studies of lithium-based surface chemistry for fusion plasma-facing materials applications. In: Journal of Nuclear Materials. 2009 ; Vol. 390-391, No. 1. pp. 942-946.
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Allain, JP, Rokusek, DL, Harilal, SS, Nieto-Perez, M, Skinner, CH, Kugel, HW, Heim, B, Kaita, R & Majeski, R 2009, 'Experimental studies of lithium-based surface chemistry for fusion plasma-facing materials applications', Journal of Nuclear Materials, vol. 390-391, no. 1, pp. 942-946. https://doi.org/10.1016/j.jnucmat.2009.01.242

Experimental studies of lithium-based surface chemistry for fusion plasma-facing materials applications. / Allain, J. P.; Rokusek, D. L.; Harilal, S. S.; Nieto-Perez, M.; Skinner, C. H.; Kugel, H. W.; Heim, B.; Kaita, R.; Majeski, R.

In: Journal of Nuclear Materials, Vol. 390-391, No. 1, 15.06.2009, p. 942-946.

Research output: Contribution to journalArticle

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AU - Allain, J. P.

AU - Rokusek, D. L.

AU - Harilal, S. S.

AU - Nieto-Perez, M.

AU - Skinner, C. H.

AU - Kugel, H. W.

AU - Heim, B.

AU - Kaita, R.

AU - Majeski, R.

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