Hydrogen retention in lithium on metallic walls from “in vacuo” analysis in LTX and implications for high-Z plasma-facing components in NSTX-U

Kaita, R.; Lucia, M.; Allain, J. P.; Bedoya, F.; Bell, R.; Boyle, D.; Capece, A.; Jaworski, M.; Koel, B. E.; Majeski, R.; Roszell, J.; Schmitt, J.; Scotti, F.; Skinner, C. H.; Soukhanovskii, V.

doi:10.1016/j.fusengdes.2016.06.056

Title: Hydrogen retention in lithium on metallic walls from “in vacuo” analysis in LTX and implications for high-Z plasma-facing components in NSTX-U

Journal Article · Mon Jul 18 00:00:00 EDT 2016 · Fusion Engineering and Design

DOI:https://doi.org/10.1016/j.fusengdes.2016.06.056· OSTI ID:1512618

Kaita, R. ^[1]; Lucia, M. ^[1]; Allain, J. P. ^[2]; Bedoya, F. ^[2]; Bell, R. ^[1]; Boyle, D. ^[1]; Capece, A. ^[3]; Jaworski, M. ^[1]; Koel, B. E. ^[4]; Majeski, R. ^[1]; Roszell, J. ^[4]; Schmitt, J. ^[1]; Scotti, F. ^[5]; Skinner, C. H. ^[1]; Soukhanovskii, V. ^[5]

Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Univ. of Illinois, Urbana, IL (United States). Dept. of Nuclear, Plasma, & Radiological Engineering
The College of New Jersey, Ewing, NJ (United States). Dept. of Physics
Princeton Univ., NJ (United States). Dept. of Chemical & Biological Engineering
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

The application of lithium to plasma-facing components (PFCs) has long been used as a technique for wall conditioning in magnetic confinement devices to improve plasma performance. Determining the characteristics of PFCs at the time of exposure to the plasma, however, is difficult because they can only be analyzed after venting the vacuum vessel and removing them at the end of an operational period. The Materials Analysis and Particle Probe (MAPP) addresses this problem here by enabling PFC samples to be exposed to plasmas, and then withdrawn into an analysis chamber without breaking vacuum. The MAPP system was used to introduce samples that matched the metallic PFCs of the Lithium Tokamak Experiment (LTX). Lithium that was subsequently evaporated onto the walls also covered the MAPP samples, which were then subject to LTX discharges. In vacuo extraction and analysis of the samples indicated that lithium oxide formed on the PFCs, but improved plasma performance persisted in LTX. The reduced recycling this suggests is consistent with separate surface science experiments that demonstrated deuterium retention in the presence of lithium oxide films. Since oxygen decreases the thermal stability of the deuterium in the film, the release of deuterium was observed below the lithium deuteride dissociation temperature. This may explain what occurred when lithium was applied to the surface of the NSTX Liquid Lithium Divertor (LLD). The LLD had segments with individual heaters, and the deuterium-alpha emission was clearly lower in the cooler regions. The plan for NSTX-U is to replace the graphite tiles with high-Z PFCs, and apply lithium to their surfaces with lithium evaporation. Experiments with lithium coatings on such PFCs suggest that deuterium could still be retained if lithium compounds form, but limiting their surface temperatures may be necessary.

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Research Organization:: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States); Univ. of Illinois at Urbana-Champaign, IL (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Grant/Contract Number:: AC52-07NA27344; AC02-09CH11466; SC0010717

OSTI ID:: 1512618

Alternate ID(s):: OSTI ID: 1416200

Report Number(s):: LLNL-JRNL-771458; 960989

Journal Information:: Fusion Engineering and Design, Vol. 117; ISSN 0920-3796

Publisher:: ElsevierCopyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 16 works

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Hydrogen Retention in Lithium on Metallic Walls from “In Vacuo” Analysis in LTX and Implications for High-Z Plasma-Facing Components in NSTX-U Kaita, R.; Lucia, M.; Allain, J. P. Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States) https://doi.org/10.11578/1367156	dataset	January 2016
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Fusion applications for lithium: wall conditioning in magnetic confinement devices Kaita, Robert Plasma Physics and Controlled Fusion, Vol. 61, Issue 11 https://doi.org/10.1088/1361-6587/ab4156	journal	October 2019
Self-consistent modelling of a liquid metal box-type divertor with application to the divertor tokamak test facility: Li versus Sn Nallo, G. F.; Mazzitelli, G.; Savoldi, L. Nuclear Fusion, Vol. 59, Issue 6 https://doi.org/10.1088/1741-4326/ab145b	journal	May 2019
Hydrogen Retention in Lithium on Metallic Walls from "In Vacuo" Analysis in LTX and Implications for High-Z Plasma-Facing Components in NSTX-U Kaita, R.; Lucia, M.; Allain, J. Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States) https://doi.org/10.11578/1562002	dataset	January 2016
Experiments on the Frascati Tokamak Upgrade with a liquid tin limiter Mazzitelli, G.; Apicella, M. L.; Iafrati, M. Nuclear Fusion, Vol. 59, Issue 9 https://doi.org/10.1088/1741-4326/ab1d70	journal	July 2019
Hydrogen Retention in Lithium on Metallic Walls from “In Vacuo” Analysis in LTX and Implications for High-Z Plasma-Facing Components in NSTX-U Kaita, R.; Lucia, M.; Allain, J. P. Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States) https://doi.org/10.11578/1367156	dataset	January 2016