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Title: Testing of Liquid Lithium Limiters in CDX-U

Abstract

Part of the development of liquid metals as a first wall or divertor for reactor applications must involve the investigation of plasma-liquid metal interactions in a functioning tokamak. Most of the interest in liquid-metal walls has focused on lithium. Experiments with lithium limiters have now been conducted in the Current Drive Experiment-Upgrade (CDX-U) device at the Princeton Plasma Physics Laboratory. Initial experiments used a liquid-lithium rail limiter (L3) built by the University of California at San Diego. Spectroscopic measurements showed some reduction of impurities in CDX-U plasmas with the L3, compared to discharges with a boron carbide limiter. While no reduction in recycling was observed with the L3, which had a plasma-wet area of approximately 40 cm2, subsequent experiments with a larger area fully toroidal lithium limiter demonstrated significant reductions in both recycling and in impurity levels. Two series of experiments with the toroidal limiter have now be en performed. In each series, the area of exposed, clean lithium was increased, until in the latest experiments the liquid-lithium plasma-facing area was increased to 2000 cm2. Under these conditions, the reduction in recycling required a factor of eight increase in gas fueling in order to maintain the plasma density. The loopmore » voltage required to sustain the plasma current was reduced from 2 V to 0.5 V. This paper summarizes the technical preparations for lithium experiments and the conditioning required to prepare the lithium surface for plasma operations. The mechanical response of the liquid metal to induced currents, especially through contact with the plasma, is discussed. The effect of the lithium-filled toroidal limiter on plasma performance is also briefly described.« less

Authors:
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Publication Date:
Research Org.:
Princeton Plasma Physics Lab., Princeton, NJ (US)
Sponsoring Org.:
USDOE Office of Science (SC) (US)
OSTI Identifier:
828582
Report Number(s):
PPPL-3988
TRN: US0404031
DOE Contract Number:  
AC02-76CH03073
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 30 Jul 2004
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BORON CARBIDES; CALIFORNIA; DIVERTORS; ELECTRIC CURRENTS; FIRST WALL; IMPURITIES; LIQUID METALS; LITHIUM; PERFORMANCE; PHYSICS; PLASMA; PLASMA DENSITY; RECYCLING; TESTING; EDGE PLASMA; LIMITERS; PLASMA-WALL INTERACTION; SPHERICAL TOKAMAK

Citation Formats

R. Majeski, R. Kaita, M. Boaz, P. Efthimion, T. Gray, B. Jones, D. Hoffman, H. Kugel, J. Menard, T. Munsat, A. Post-Zwicker, V. Soukhanovskii, J. Spaleta, G. Taylor, J. Timberlake, R. Woolley, L. Zakharov, M. Finkenthal, D. Stutman, G. Antar, R. Doerner, S. Luckhardt, R. Seraydarian, R. Maingi, M. Maiorano, S. Smith, and D. Rodgers. Testing of Liquid Lithium Limiters in CDX-U. United States: N. p., 2004. Web. doi:10.2172/828582.
R. Majeski, R. Kaita, M. Boaz, P. Efthimion, T. Gray, B. Jones, D. Hoffman, H. Kugel, J. Menard, T. Munsat, A. Post-Zwicker, V. Soukhanovskii, J. Spaleta, G. Taylor, J. Timberlake, R. Woolley, L. Zakharov, M. Finkenthal, D. Stutman, G. Antar, R. Doerner, S. Luckhardt, R. Seraydarian, R. Maingi, M. Maiorano, S. Smith, & D. Rodgers. Testing of Liquid Lithium Limiters in CDX-U. United States. doi:10.2172/828582.
R. Majeski, R. Kaita, M. Boaz, P. Efthimion, T. Gray, B. Jones, D. Hoffman, H. Kugel, J. Menard, T. Munsat, A. Post-Zwicker, V. Soukhanovskii, J. Spaleta, G. Taylor, J. Timberlake, R. Woolley, L. Zakharov, M. Finkenthal, D. Stutman, G. Antar, R. Doerner, S. Luckhardt, R. Seraydarian, R. Maingi, M. Maiorano, S. Smith, and D. Rodgers. Fri . "Testing of Liquid Lithium Limiters in CDX-U". United States. doi:10.2172/828582. https://www.osti.gov/servlets/purl/828582.
@article{osti_828582,
title = {Testing of Liquid Lithium Limiters in CDX-U},
author = {R. Majeski and R. Kaita and M. Boaz and P. Efthimion and T. Gray and B. Jones and D. Hoffman and H. Kugel and J. Menard and T. Munsat and A. Post-Zwicker and V. Soukhanovskii and J. Spaleta and G. Taylor and J. Timberlake and R. Woolley and L. Zakharov and M. Finkenthal and D. Stutman and G. Antar and R. Doerner and S. Luckhardt and R. Seraydarian and R. Maingi and M. Maiorano and S. Smith and D. Rodgers},
abstractNote = {Part of the development of liquid metals as a first wall or divertor for reactor applications must involve the investigation of plasma-liquid metal interactions in a functioning tokamak. Most of the interest in liquid-metal walls has focused on lithium. Experiments with lithium limiters have now been conducted in the Current Drive Experiment-Upgrade (CDX-U) device at the Princeton Plasma Physics Laboratory. Initial experiments used a liquid-lithium rail limiter (L3) built by the University of California at San Diego. Spectroscopic measurements showed some reduction of impurities in CDX-U plasmas with the L3, compared to discharges with a boron carbide limiter. While no reduction in recycling was observed with the L3, which had a plasma-wet area of approximately 40 cm2, subsequent experiments with a larger area fully toroidal lithium limiter demonstrated significant reductions in both recycling and in impurity levels. Two series of experiments with the toroidal limiter have now be en performed. In each series, the area of exposed, clean lithium was increased, until in the latest experiments the liquid-lithium plasma-facing area was increased to 2000 cm2. Under these conditions, the reduction in recycling required a factor of eight increase in gas fueling in order to maintain the plasma density. The loop voltage required to sustain the plasma current was reduced from 2 V to 0.5 V. This paper summarizes the technical preparations for lithium experiments and the conditioning required to prepare the lithium surface for plasma operations. The mechanical response of the liquid metal to induced currents, especially through contact with the plasma, is discussed. The effect of the lithium-filled toroidal limiter on plasma performance is also briefly described.},
doi = {10.2172/828582},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2004},
month = {7}
}