March 2012

Conference Paper

NSTX plasma response to lithium coated divertor

By:
Kugel, H.; Bell, M.; Allain, J.; Bell, R. E.; Ding, S.; Gerhardt, S.P.; Jaworski, M. A.; Kaita, R.; Kallman, J.; Kaye, S.; LeBlanc, B; Maingi, Rajesh ; Majeski, R.; Maqueda, R. J.; Mansfield, D.K.; Mueller, D.; Nygren, R. E.; Paul, S.; Raman, R.; Roquemore, A. L.; Sabbagh, S. A.; Schneider, H; Skinner, C.; Soukhanovskii, V. A.; Taylor, C.; Timberlake, J.; Wampler, W. R.; Zakharov, L.; Zweben, S.
Journal Name:
Journal of Nuclear Materials
Page Number:
400-404
Volume:
415
Issue Number:
1
Publication Date:
March 2012
Conference Name:
19th International Conference on Plasma-Surface Interactions in Controlled Fusion Devices (PSI)
Conference Location:
San Diego, California, United States of America
Conference Sponsor:
Lawrence Livermore National Laboratory
View DOI Listing:
https://doi.org/10.1016/j.jnucmat.2010.12.016

Abstract

NSTX experiments have explored lithium evaporated on a graphite divertor and other plasma-facing components in both L- and H- mode confinement regimes heated by high-power neutral beams. Improvements in plasma performance have followed these lithium depositions, including a reduction and eventual elimination of the HeGDC time between discharges, reduced edge neutral density, reduced plasma density, particularly in the edge and the SOL, increased pedestal electron and ion temperature, improved energy confinement and the suppression of ELMs in the H-mode. However, with improvements in confinement and suppression of ELMs, there was a significant secular increase in the effective ion charge Z(eff) and the radiated power in H-mode plasmas as a result of increases in the carbon and medium-Z metallic impurities. Lithium itself remained at a very low level in the plasma core, < 0.1%. Initial results are reported from operation with a Liquid Lithium Divertor (LLD) recently installed. (C) 2010 Elsevier B.V. All rights reserved.