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October 7, 2011
LITHIUMIZATION OF PLASMAFACING COMPONENTS IN
NEXT-GEN FUSION REACTORS
Anupama Khan
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Why develop fusion energy?
Fusion energy deployment scenarios match
long-term carbon mitigation projections.
Fusion Development Plan
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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 Challenges
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High power flux from radiation and particles
Erosion of structural materials
Pumping/gettering impurities (N, H2O, CO)
Hydrogen recycling and retention
Goal: Choose multi-functional materials that resist
erosion and improve plasma performance over
extended periods of time.
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Why use liquid lithium PFCs?
Liquid lithium PFCs have been shown to improve
several plasma performance parameters, though
the mechanisms remain poorly characterized.
Observed Benefits of Liquid Lithium
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Limited Li sputtering
Suppresses off-normal events
Reduced D,T recycling
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Surface chemistry?
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Kugel, H., et al. “Lithium coatings on NSTX plasma-facing
components.” Fusion Engineering and Design. 85 (2010) 865-873.
Two-Fold Approach
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Observation
Surface
Chemistry of
PFCs
Imaging
exposed LLD
samples
Mapping
damage
patterns
Lithiated ATJ
graphite
Experiment
Boron preconditioning on
Mo alloys
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Why study damaged surfaces?
Li predicted to protect porous Mo from neutral
beam bombardment, prolong lifetime of
structural materials in NSTX.
Narrow Band of Damage
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Abrams, T. “Investigation of LLD Test Sample Performance under High Heat Loads.” Unpublished data. (2010).
SEM: No Beam Exposure
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SEM: Beam Exposure
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SEM: Lithium and Beam Exposure
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Current Work
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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
Summary
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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
Acknowledgements
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Prof. Bernasek
Prof. Rob Goldston
Dr. Bob Kaita
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Chemistry Department
PEI Grand Challenges
PPPL
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Steve Wulfsberg
Matt Frith
Sean Edington
Conor Thomas
Pearl Dickerson
Amber Hibberd
Esther Frederick
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Thank You!
Questions?