Chemical response of lithiated graphite with deuterium irradiation
Date of this Version
3-1-2011Citation
J. Appl. Phys. 109, 053306 (2011)
Abstract
Lithium wall conditioning has been found to enhance plasma performance for graphite walled fusion devices such as TFTR, CDX-U, T-11M, TJ-II and NSTX. Among observed plasma enhancements is a reduction in edge density and reduced deuterium recycling. The mechanism by which lithiated graphite retains deuterium is largely unknown. Under controlled laboratory conditions, X-ray photoelectron spectroscopy (XPS) is used to observe the chemical changes that occur on ATJ graphite after lithium deposition. The chemical state of lithiated graphite is found to change upon deuterium irradiation indicating the formation Li-O-D, manifest at 532.9 +/- 0.6 eV. Lithium-deuterium interactions are also manifest in the C 1s photoelectron energy range and show Li-C-D interactions at 291.2 +/- 60.6 eV. Post-mortem NSTX tiles that have been exposed to air upon extraction are cleaned and examined, revealing the chemical archaeology that formed during NSTX operations. XPS spectra show strong correlation (+/- 0.3 eV) in Li-O-D and Li-O peaks from post-mortem and control experiments, thus validating offline experiments. We report findings that show that deuterium is found to interact with lithium after lithium has already reacted with carbon and oxygen. (C) 2011 American Institute of Physics. [doi:10.1063/1.3555097]
Discipline(s)
Nanoscience and Nanotechnology
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Copyright (2011) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in J. Appl. Phys. 109, 053306 (2011) and may be found at http://dx.doi.org/10.1063/1.3555097. The following article has been submitted to/accepted by Journal of Applied Physics. Copyright (2011) C. N. Taylor, B. Heim and J. P. Allain. This article is distributed under a Creative Commons Attribution 3.0 Unported License.