LITHIUMIZATION OF PLASMA-FACING COMPONENTS IN NEXT-GEN FUSION REACTORSAnupama Khan
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October 7, 2011
Fusion energy deployment scenarios match long-term carbon mitigation projections.
Why develop fusion energy?
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Fusion Development Plan3
Goldston, R. “Fusion Development Path Panel: Preliminary Report.” Report to the Fusion Sciences Advisory Committee (2002).
Demo of commercial fusion energy by 2040.
Projected Emissions Reductions
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Metz, B. et al (eds). Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press (2007).
IPCC predicts 95% of reductions made after 2030.
Materials Challenges5
High power flux from radiation and particles
Erosion of structural materials Pumping/gettering impurities (N, H2O,
CO) Hydrogen recycling and retentionGoal: Choose multi-functional
materials that resist erosion and improve plasma performance over
extended periods of time.
Liquid lithium PFCs have been shown to improve several plasma performance parameters, though the mechanisms remain poorly characterized.
Why use liquid lithium PFCs?
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Observed Benefits of Liquid Lithium
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Limited Li sputtering Suppresses off-normal events Reduced D,T recycling
Surface chemistry?
Kugel, H., et al. “Lithium coatings on NSTX plasma-facing components.” Fusion Engineering and Design. 85 (2010) 865-873.
Li predicted to protect porous Mo from neutral beam bombardment, prolong lifetime of structural materials in NSTX.
Why study damaged surfaces?
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Narrow Band of Damage 10
Abrams, T. “Investigation of LLD Test Sample Performance under High Heat Loads.” Unpublished data. (2010).
Current Work14
Stitch together “panorama” sweeping length of sample to identify changes in morphology
Energy-dispersed X-ray spectroscopy for analysis of elemental composition in Li’ized samples
Determine changes in crystal structure after beam exposure in samples with and without lithium
Remove lithium and image underlying Mo structures
Summary15
Fusion has the potential to significantly impact global energy consumption over the next 100 years
Liquid lithium is a multi-functional material that has been shown to improve plasma performance
SEM to study heat diffusion in Li on porous Mo
XPS to study interactions between O-B-Li