Lithium Surface Coatings for Improved Plasma Performance in NSTX
Authors: H.W. Kugel, M. G. Bell, J-W. Ahn, J.P. Allain, R. Bell , J. Boedo, C. Bush, D. Gates, T. Gray,S. Kaye, R. Kaita, B. LeBlanc, R. Maingi, R. Majeski, D. Mansfield, J. Menard, D. Mueller, M. Ono, S. Paul, R. Raman, A.L. Roquemore, P.W. Ross, S. Sabbagh, H. Schneider, C. H. Skinner, V. Soukhanovskii, T. Stevenson, J. Timberlake, W.R. Wampler, and L. Zakharov
Abstract:
NSTX high-power divertor plasma experiments have shown, for the first time,
significant and frequent benefits from lithium coatings applied to plasma facing
components. Lithium pellet injection on NSTX introduced lithium pellets with masses 1
to 5 mg via He discharges. Lithium coatings have also been applied with an oven that
directed a collimated stream of lithium vapor toward the graphite tiles of the lower center
stack and divertor. Lithium depositions from a few mg to 1 g have been applied between
discharges. Benefits from the lithium coating were sometimes, but not always seen.
These improvements sometimes included decreases plasma density, inductive flux
consumption, and ELM frequency, and increases in electron temperature, ion
temperature, energy confinement and periods of MHD quiescence. In addition,
reductions in lower divertor D, C, and O luminosity were measured.
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Presented at: Forty-Ninth APS Division of Plasma Physics Meeting, 12 - 16 November 2007, Orlando, Florida USA
Submitted to: Physics of Plasmas
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Download PPPL-4290 (pdf 2.17 M)
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