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.

Two-Fold Approach8

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 Unpublished data.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).

SEM: No Beam Exposure11

SEM: Beam Exposure12

SEM: Lithium and Beam Exposure

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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

Acknowledgements16

Questions?

Thank You!17