PPPL-4786
Comparison of H-Mode Plasmas Diverted to Solid and Liquid Lithium Surfaces
Authors: R. Kaita, et. al.
Abstract:
Experiments were conducted with a Liquid Lithium Divertor (LLD) in NSTX. Among the
goals was to use lithium recoating to sustain deuterium (D) retention by a static liquid lithium
surface, approximating the ability of flowing liquid lithium to maintain chemical reactivity.
Lithium evaporators were used to deposit lithium on the LLD surface. Improvements in
plasma edge conditions were similar to those with lithiated graphite plasma-facing
components (PFCs), including an increase in confinement over discharges without lithiumcoated
PFCs and ELM reduction during H-modes. With the outer strike point on the LLD, the
D retention in the LLD was about the same as that for solid lithium coatings on graphite, or
about two times that achieved without lithium PFC coatings. There were also indications of
contamination of the LLD surface, possibly due erosion and redeposition of carbon from
PFCs. Flowing lithium may thus be needed for chemically active PFCs during long-pulse
operation.
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Submitted to: Journal of Nuclear Materials (May 2012) Presented at: 20th International Conference on Plasma Surface Interactions 2012, Aachen, Germany (May 21-25, 2012)
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