Lithium coatings on NSTX plasma facing components and its effects on boundary control, core plasma performance, and operation

Journal Article · Fri Jan 01 00:00:00 EST 2010 · Fusion Engineering and Design

DOI:https://doi.org/10.1016/j.fusengdes.2010.04.004· OSTI ID:1081808

Kugel, H. W. ^[1]; Bell, M. G. ^[1]; Maingi, R. ^[2]

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1. Princeton Plasma Physics Laboratory (PPPL)
2. Oak Ridge National Laboratory (ORNL)

NSTX high power divertor plasma experiments have used in succession lithium pellet injection (LPI), evaporated lithium, and injected lithium powder to apply lithium coatings to graphite plasma facing components. In 2005, following the wall conditioning and LPI, discharges exhibited edge density reduction and performance improvements. Since 2006, first one, and now two lithium evaporators have been used routinely to evaporate lithium onto the lower divertor region at total rates of 10-70 mg/min for periods 5-10 min between discharges. Prior to each discharge, the evaporators are withdrawn behind shutters. Significant improvements in the performance of NBI heated divertor discharges resulting from these lithium depositions were observed. These evaporators are now used for more than 80% of NSTX discharges. Initial work with injecting fine lithium powder into the edge of NBI heated deuterium discharges yielded comparable changes in performance. Several operational issues encountered with lithium wall conditions, and the special procedures needed for vessel entry are discussed. The next step in this work is installation of a liquid lithium divertor surface on the outer part of the lower divertor.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1081808
• Journal Information: Fusion Engineering and Design, Vol. 85, Issue 6; ISSN 0920-3796
• Country of Publication: United States
• Language: English