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Title: Plasma Performance Improvement with Lithium-Coated Plasma-Facing Components in NSTX

Abstract

Lithium as a plasma-facing material has many attractive features, including a reduction in the recycling of hydrogenic species and the potential for withstanding high heat and neutron fluxes in fusion reactors. Recent NSTX experiments have shown, for the first time, significant and recurring benefits of lithium coatings on plasma-facing components (PFC's) to the performance of divertor plasmas in both L- and H- mode confinement regimes heated by high-power neutral beams. They included decreases in the plasma density and inductive flux consumption, and increases in the electron temperature, ion temperature, energy confinement time, and DD neutron rate. Extended periods of MHD quiescence were also achieved, and measurements of the visible emission from the lower divertor showed a reduction in the deuterium, carbon, and oxygen line emission. Other salient results with lithium evaporation included a broadening of the electron temperature profile, and changes in edge density gradients that benefited electron Bernstein wave coupling. There was also a reduction in ELM frequency and amplitude, followed by a period of complete ELM suppression. In general, it was observed that both the best and the average confinement occurred after lithium deposition and that the increase in WMHD occurs mostly through an increase in We. Inmore » addition, a liquid lithium divertor (LLD) is being installed on NSTX this year. As the first fully-toroidal liquid metal divertor target, experiments with the LLD can provide insight into the behavior of metallic ITER PFC's should they liquefy during high-power divertor tokamak operations. The NSTX lithium coating and LLD experiments are important near-term steps in demonstrating the potential of liquid lithium as a solution to the first-wall problem for both magnetic and inertial fusion reactors.« less

Authors:
Publication Date:
Research Org.:
Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
938960
Report Number(s):
PPPL-4353
TRN: US0806783
DOE Contract Number:  
DE-ACO2-76CHO3073
Resource Type:
Conference
Resource Relation:
Conference: Twenty-Second IAEA Fusion Energy Conference - 50th Anniversary Controlled Nuclear Fusion Research, 13-18 October, 2008 Geneva, Switzerland
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CARBON; COATINGS; CONFINEMENT; CONFINEMENT TIME; DEPOSITION; DEUTERIUM; DIVERTORS; ELECTRON TEMPERATURE; ELECTRONS; EVAPORATION; FIRST WALL; IAEA; ION TEMPERATURE; LIQUID METALS; LITHIUM; NEUTRONS; OXYGEN; PLASMA DENSITY; RECYCLING; THERMONUCLEAR REACTORS; NCSX; Magnetic Fields

Citation Formats

Kaita, R., et. al. Plasma Performance Improvement with Lithium-Coated Plasma-Facing Components in NSTX. United States: N. p., 2008. Web.
Kaita, R., et. al. Plasma Performance Improvement with Lithium-Coated Plasma-Facing Components in NSTX. United States.
Kaita, R., et. al. Mon . "Plasma Performance Improvement with Lithium-Coated Plasma-Facing Components in NSTX". United States. https://www.osti.gov/servlets/purl/938960.
@article{osti_938960,
title = {Plasma Performance Improvement with Lithium-Coated Plasma-Facing Components in NSTX},
author = {Kaita, R., et. al.},
abstractNote = {Lithium as a plasma-facing material has many attractive features, including a reduction in the recycling of hydrogenic species and the potential for withstanding high heat and neutron fluxes in fusion reactors. Recent NSTX experiments have shown, for the first time, significant and recurring benefits of lithium coatings on plasma-facing components (PFC's) to the performance of divertor plasmas in both L- and H- mode confinement regimes heated by high-power neutral beams. They included decreases in the plasma density and inductive flux consumption, and increases in the electron temperature, ion temperature, energy confinement time, and DD neutron rate. Extended periods of MHD quiescence were also achieved, and measurements of the visible emission from the lower divertor showed a reduction in the deuterium, carbon, and oxygen line emission. Other salient results with lithium evaporation included a broadening of the electron temperature profile, and changes in edge density gradients that benefited electron Bernstein wave coupling. There was also a reduction in ELM frequency and amplitude, followed by a period of complete ELM suppression. In general, it was observed that both the best and the average confinement occurred after lithium deposition and that the increase in WMHD occurs mostly through an increase in We. In addition, a liquid lithium divertor (LLD) is being installed on NSTX this year. As the first fully-toroidal liquid metal divertor target, experiments with the LLD can provide insight into the behavior of metallic ITER PFC's should they liquefy during high-power divertor tokamak operations. The NSTX lithium coating and LLD experiments are important near-term steps in demonstrating the potential of liquid lithium as a solution to the first-wall problem for both magnetic and inertial fusion reactors.},
doi = {},
url = {https://www.osti.gov/biblio/938960}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2008},
month = {9}
}

Conference:
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