Recent liquid lithium limiter experiments in CDX-U

R. Majeski*, S. Jardin, R. Kaita, T. Gray, P. Marfuta, J. Spaleta, J. Timberlake, L. Zakharov, G. Antar, R. Doerner, S. Luckhardt, R. Seraydarian, V. Soukhanovskii, R. Maingi, M. Finkenthal, D. Stutman, D. Rodgers, S. Angelini

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

104 Scopus citations

Abstract

Recent experiments in the Current Drive Experiment-Upgrade (CDX-U) provide a first-ever test of large area liquid lithium surfaces as a tokamak first wall to gain engineering experience with a liquid metal first wall and to investigate whether very low recycling plasma regimes can be accessed with lithium walls. The CDX-U is a compact (R = 34 cm, a = 22 cm, Btoroidal = 2 kG, I P = 100 kA, Te(0)∼ 100 eV, ne(0) ∼ 5 × 1019 m-3) spherical torus at the Princeton Plasma Physics Laboratory. A toroidal liquid lithium pool limiter with an area of 2000 cm2 (half the total plasma limiting surface) has been installed in CDX-U. Tokamak discharges which used the liquid lithium pool limiter required a fourfold lower loop voltage to sustain the plasma current, and a factor of 5-8 increase in gas fuelling to achieve a comparable density, indicating that recycling is strongly reduced. Modelling of the discharges demonstrated that the lithium limited discharges are consistent with Zeffective < 1.2 (compared with 2.4 for the pre-lithium discharges), a broadened current channel and a 25% increase in the core electron temperature. Spectroscopic measurements indicate that edge oxygen and carbon radiation are strongly reduced.

Original languageEnglish
Pages (from-to)519-523
Number of pages5
JournalNuclear Fusion
Volume45
Issue number6
DOIs
StatePublished - 1 Jun 2005
Externally publishedYes

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