Recent progress in the NSTX/NSTX-U lithium programme and prospects for reactor-relevant liquid-lithium based divertor development

M. Ono, M. A. Jaworski, R. Kaita, H. W. Kugel, J. W. Ahn, J. P. Allain, M. G. Bell, R. E. Bell, D. J. Clayton, J. M. Canik, S. Ding, S. Gerhardt, T. K. Gray, W. Guttenfelder, Y. Hirooka, J. Kallman, S. Kaye, D. Kumar, B. P. Leblanc, R. Maingi & 17 others D. K. Mansfield, A. McLean, J. Menard, D. Mueller, R. Nygren, S. Paul, M. Podesta, R. Raman, Y. Ren, S. Sabbagh, F. Scotti, C. H. Skinner, V. Soukhanovskii, V. Surla, C. N. Taylor, J. Timberlake, L. E. Zakharov

Research output: Research - peer-reviewArticle

Abstract

Developing a reactor-compatible divertor has been identified as a particularly challenging technology problem for magnetic confinement fusion. Application of lithium (Li) in NSTX resulted in improved H-mode confinement, H-mode power threshold reduction, and other plasma performance benefits. During the 2010 NSTX campaign, application of a relatively modest amount of Li (300 mg prior to the discharge) resulted in a ∼50% reduction in heat load on the liquid lithium divertor (LLD) attributable to enhanced divertor bolometric radiation. These promising Li results in NSTX and related modelling calculations motivated the radiative LLD concept proposed here. Li is evaporated from the liquid lithium (LL) coated divertor strike-point surface due to the intense heat flux. The evaporated Li is readily ionized by the plasma due to its low ionization energy, and the poor Li particle confinement near the divertor plate enables ionized Li ions to radiate strongly, resulting in a significant reduction in the divertor heat flux. This radiative process has the desired effect of spreading the localized divertor heat load to the rest of the divertor chamber wall surfaces, facilitating the divertor heat removal. The LL coating of divertor surfaces can also provide a 'sacrificial' protective layer to protect the substrate solid material from transient high heat flux such as the ones caused by the edge localized modes. By operating at lower temperature than the first wall, the LL covered large divertor chamber wall surfaces can serve as an effective particle pump for the entire reactor chamber, as impurities generally migrate towards lower temperature LL divertor surfaces. To maintain the LL purity, a closed LL loop system with a modest circulating capacity (e.g., ∼1 l s-1 for ∼1% level 'impurities') is envisioned for a steady-state 1 GW-electric class fusion power plant.

LanguageEnglish (US)
Article number113030
JournalNuclear Fusion
Volume53
Issue number11
DOIs
StatePublished - Nov 2013
Externally publishedYes

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liquid lithium
lithium
reactors
heat flux
chambers
heat
fusion
impurities
power plants
purity
pumps
coatings
ionization
thresholds
radiation
ions
energy

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

Cite this

Recent progress in the NSTX/NSTX-U lithium programme and prospects for reactor-relevant liquid-lithium based divertor development. / Ono, M.; Jaworski, M. A.; Kaita, R.; Kugel, H. W.; Ahn, J. W.; Allain, J. P.; Bell, M. G.; Bell, R. E.; Clayton, D. J.; Canik, J. M.; Ding, S.; Gerhardt, S.; Gray, T. K.; Guttenfelder, W.; Hirooka, Y.; Kallman, J.; Kaye, S.; Kumar, D.; Leblanc, B. P.; Maingi, R.; Mansfield, D. K.; McLean, A.; Menard, J.; Mueller, D.; Nygren, R.; Paul, S.; Podesta, M.; Raman, R.; Ren, Y.; Sabbagh, S.; Scotti, F.; Skinner, C. H.; Soukhanovskii, V.; Surla, V.; Taylor, C. N.; Timberlake, J.; Zakharov, L. E.

In: Nuclear Fusion, Vol. 53, No. 11, 113030, 11.2013.

Research output: Research - peer-reviewArticle

Ono, M, Jaworski, MA, Kaita, R, Kugel, HW, Ahn, JW, Allain, JP, Bell, MG, Bell, RE, Clayton, DJ, Canik, JM, Ding, S, Gerhardt, S, Gray, TK, Guttenfelder, W, Hirooka, Y, Kallman, J, Kaye, S, Kumar, D, Leblanc, BP, Maingi, R, Mansfield, DK, McLean, A, Menard, J, Mueller, D, Nygren, R, Paul, S, Podesta, M, Raman, R, Ren, Y, Sabbagh, S, Scotti, F, Skinner, CH, Soukhanovskii, V, Surla, V, Taylor, CN, Timberlake, J & Zakharov, LE 2013, 'Recent progress in the NSTX/NSTX-U lithium programme and prospects for reactor-relevant liquid-lithium based divertor development' Nuclear Fusion, vol 53, no. 11, 113030. DOI: 10.1088/0029-5515/53/11/113030
Ono, M. ; Jaworski, M. A. ; Kaita, R. ; Kugel, H. W. ; Ahn, J. W. ; Allain, J. P. ; Bell, M. G. ; Bell, R. E. ; Clayton, D. J. ; Canik, J. M. ; Ding, S. ; Gerhardt, S. ; Gray, T. K. ; Guttenfelder, W. ; Hirooka, Y. ; Kallman, J. ; Kaye, S. ; Kumar, D. ; Leblanc, B. P. ; Maingi, R. ; Mansfield, D. K. ; McLean, A. ; Menard, J. ; Mueller, D. ; Nygren, R. ; Paul, S. ; Podesta, M. ; Raman, R. ; Ren, Y. ; Sabbagh, S. ; Scotti, F. ; Skinner, C. H. ; Soukhanovskii, V. ; Surla, V. ; Taylor, C. N. ; Timberlake, J. ; Zakharov, L. E./ Recent progress in the NSTX/NSTX-U lithium programme and prospects for reactor-relevant liquid-lithium based divertor development. In: Nuclear Fusion. 2013 ; Vol. 53, No. 11.
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abstract = "Developing a reactor-compatible divertor has been identified as a particularly challenging technology problem for magnetic confinement fusion. Application of lithium (Li) in NSTX resulted in improved H-mode confinement, H-mode power threshold reduction, and other plasma performance benefits. During the 2010 NSTX campaign, application of a relatively modest amount of Li (300 mg prior to the discharge) resulted in a ∼50% reduction in heat load on the liquid lithium divertor (LLD) attributable to enhanced divertor bolometric radiation. These promising Li results in NSTX and related modelling calculations motivated the radiative LLD concept proposed here. Li is evaporated from the liquid lithium (LL) coated divertor strike-point surface due to the intense heat flux. The evaporated Li is readily ionized by the plasma due to its low ionization energy, and the poor Li particle confinement near the divertor plate enables ionized Li ions to radiate strongly, resulting in a significant reduction in the divertor heat flux. This radiative process has the desired effect of spreading the localized divertor heat load to the rest of the divertor chamber wall surfaces, facilitating the divertor heat removal. The LL coating of divertor surfaces can also provide a 'sacrificial' protective layer to protect the substrate solid material from transient high heat flux such as the ones caused by the edge localized modes. By operating at lower temperature than the first wall, the LL covered large divertor chamber wall surfaces can serve as an effective particle pump for the entire reactor chamber, as impurities generally migrate towards lower temperature LL divertor surfaces. To maintain the LL purity, a closed LL loop system with a modest circulating capacity (e.g., ∼1 l s-1 for ∼1% level 'impurities') is envisioned for a steady-state 1 GW-electric class fusion power plant.",
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