Impact of lithium pellets on plasma performance in the ASDEX Upgrade all-metal-wall tokamak

P. T. Lang, R. Maingi, D. K. Mansfield, R. M. McDermott, R. Neu, E. Wolfrum, R. Arredondo Parra, M. Bernert, G. Birkenmeier, A. Diallo, M. Dunne, E. Fable, R. Fischer, B. Geiger, Antti Hakola, V. Nikolaeva, A. Kappatou, F. Laggner, M. Oberkofler, B. PloecklS. Potzel, T. Pütterich, B. Sieglin, T. Szepesi

    Research output: Contribution to journalArticleScientificpeer-review

    6 Citations (Scopus)

    Abstract

    The impact of lithium (Li) on plasma performance was investigated at the ASDEX Upgrade tokamak, which features a full tungsten wall. Li pellets containing 1.6 × 1020 Li atoms were launched with a speed of 600 m s-1 to achieve deep penetration into the plasma and minimize the impact on the first wall. Homogeneous transient Li concentrations in the plasma of up to 15% were established. The Li sustainment time in the plasma decreased with an increasing heating power from 150 to 40 ms. Due to the pellet rate being restricted to 2 Hz, no Li pile-up could take place. No significant positive impact on plasma properties, as reported from other tokamak devices, could be found; the Li pellets rather caused a small reduction in plasma energy, mainly due to enhanced radiation. Due to pellet injection, a short-lived Li layer was formed on the plasma-facing components, which lasted a few discharges and led to moderately beneficial effects during plasma start-up. Most pellets were found to trigger type-I ELMs, either by their direct local perturbation or indirectly by the altered edge conditions; however, reliability was less than 100%.

    Original languageEnglish
    Article number016030
    JournalNuclear Fusion
    Volume57
    Issue number1
    DOIs
    Publication statusPublished - 1 Jan 2017
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    pellets
    lithium
    metals
    tokamak devices
    piles
    tungsten
    penetration
    actuators
    injection
    perturbation
    heating
    radiation
    atoms

    Keywords

    • confinement
    • ELMs
    • Li pellets
    • plasma facing components
    • tokamak ASDEX upgrade

    Cite this

    Lang, P. T., Maingi, R., Mansfield, D. K., McDermott, R. M., Neu, R., Wolfrum, E., ... Szepesi, T. (2017). Impact of lithium pellets on plasma performance in the ASDEX Upgrade all-metal-wall tokamak. Nuclear Fusion, 57(1), [016030]. https://doi.org/10.1088/0029-5515/57/1/016030
    Lang, P. T. ; Maingi, R. ; Mansfield, D. K. ; McDermott, R. M. ; Neu, R. ; Wolfrum, E. ; Arredondo Parra, R. ; Bernert, M. ; Birkenmeier, G. ; Diallo, A. ; Dunne, M. ; Fable, E. ; Fischer, R. ; Geiger, B. ; Hakola, Antti ; Nikolaeva, V. ; Kappatou, A. ; Laggner, F. ; Oberkofler, M. ; Ploeckl, B. ; Potzel, S. ; Pütterich, T. ; Sieglin, B. ; Szepesi, T. / Impact of lithium pellets on plasma performance in the ASDEX Upgrade all-metal-wall tokamak. In: Nuclear Fusion. 2017 ; Vol. 57, No. 1.
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    title = "Impact of lithium pellets on plasma performance in the ASDEX Upgrade all-metal-wall tokamak",
    abstract = "The impact of lithium (Li) on plasma performance was investigated at the ASDEX Upgrade tokamak, which features a full tungsten wall. Li pellets containing 1.6 × 1020 Li atoms were launched with a speed of 600 m s-1 to achieve deep penetration into the plasma and minimize the impact on the first wall. Homogeneous transient Li concentrations in the plasma of up to 15{\%} were established. The Li sustainment time in the plasma decreased with an increasing heating power from 150 to 40 ms. Due to the pellet rate being restricted to 2 Hz, no Li pile-up could take place. No significant positive impact on plasma properties, as reported from other tokamak devices, could be found; the Li pellets rather caused a small reduction in plasma energy, mainly due to enhanced radiation. Due to pellet injection, a short-lived Li layer was formed on the plasma-facing components, which lasted a few discharges and led to moderately beneficial effects during plasma start-up. Most pellets were found to trigger type-I ELMs, either by their direct local perturbation or indirectly by the altered edge conditions; however, reliability was less than 100{\%}.",
    keywords = "confinement, ELMs, Li pellets, plasma facing components, tokamak ASDEX upgrade",
    author = "Lang, {P. T.} and R. Maingi and Mansfield, {D. K.} and McDermott, {R. M.} and R. Neu and E. Wolfrum and {Arredondo Parra}, R. and M. Bernert and G. Birkenmeier and A. Diallo and M. Dunne and E. Fable and R. Fischer and B. Geiger and Antti Hakola and V. Nikolaeva and A. Kappatou and F. Laggner and M. Oberkofler and B. Ploeckl and S. Potzel and T. P{\"u}tterich and B. Sieglin and T. Szepesi",
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    Lang, PT, Maingi, R, Mansfield, DK, McDermott, RM, Neu, R, Wolfrum, E, Arredondo Parra, R, Bernert, M, Birkenmeier, G, Diallo, A, Dunne, M, Fable, E, Fischer, R, Geiger, B, Hakola, A, Nikolaeva, V, Kappatou, A, Laggner, F, Oberkofler, M, Ploeckl, B, Potzel, S, Pütterich, T, Sieglin, B & Szepesi, T 2017, 'Impact of lithium pellets on plasma performance in the ASDEX Upgrade all-metal-wall tokamak', Nuclear Fusion, vol. 57, no. 1, 016030. https://doi.org/10.1088/0029-5515/57/1/016030

    Impact of lithium pellets on plasma performance in the ASDEX Upgrade all-metal-wall tokamak. / Lang, P. T.; Maingi, R.; Mansfield, D. K.; McDermott, R. M.; Neu, R.; Wolfrum, E.; Arredondo Parra, R.; Bernert, M.; Birkenmeier, G.; Diallo, A.; Dunne, M.; Fable, E.; Fischer, R.; Geiger, B.; Hakola, Antti; Nikolaeva, V.; Kappatou, A.; Laggner, F.; Oberkofler, M.; Ploeckl, B.; Potzel, S.; Pütterich, T.; Sieglin, B.; Szepesi, T.

    In: Nuclear Fusion, Vol. 57, No. 1, 016030, 01.01.2017.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Impact of lithium pellets on plasma performance in the ASDEX Upgrade all-metal-wall tokamak

    AU - Lang, P. T.

    AU - Maingi, R.

    AU - Mansfield, D. K.

    AU - McDermott, R. M.

    AU - Neu, R.

    AU - Wolfrum, E.

    AU - Arredondo Parra, R.

    AU - Bernert, M.

    AU - Birkenmeier, G.

    AU - Diallo, A.

    AU - Dunne, M.

    AU - Fable, E.

    AU - Fischer, R.

    AU - Geiger, B.

    AU - Hakola, Antti

    AU - Nikolaeva, V.

    AU - Kappatou, A.

    AU - Laggner, F.

    AU - Oberkofler, M.

    AU - Ploeckl, B.

    AU - Potzel, S.

    AU - Pütterich, T.

    AU - Sieglin, B.

    AU - Szepesi, T.

    PY - 2017/1/1

    Y1 - 2017/1/1

    N2 - The impact of lithium (Li) on plasma performance was investigated at the ASDEX Upgrade tokamak, which features a full tungsten wall. Li pellets containing 1.6 × 1020 Li atoms were launched with a speed of 600 m s-1 to achieve deep penetration into the plasma and minimize the impact on the first wall. Homogeneous transient Li concentrations in the plasma of up to 15% were established. The Li sustainment time in the plasma decreased with an increasing heating power from 150 to 40 ms. Due to the pellet rate being restricted to 2 Hz, no Li pile-up could take place. No significant positive impact on plasma properties, as reported from other tokamak devices, could be found; the Li pellets rather caused a small reduction in plasma energy, mainly due to enhanced radiation. Due to pellet injection, a short-lived Li layer was formed on the plasma-facing components, which lasted a few discharges and led to moderately beneficial effects during plasma start-up. Most pellets were found to trigger type-I ELMs, either by their direct local perturbation or indirectly by the altered edge conditions; however, reliability was less than 100%.

    AB - The impact of lithium (Li) on plasma performance was investigated at the ASDEX Upgrade tokamak, which features a full tungsten wall. Li pellets containing 1.6 × 1020 Li atoms were launched with a speed of 600 m s-1 to achieve deep penetration into the plasma and minimize the impact on the first wall. Homogeneous transient Li concentrations in the plasma of up to 15% were established. The Li sustainment time in the plasma decreased with an increasing heating power from 150 to 40 ms. Due to the pellet rate being restricted to 2 Hz, no Li pile-up could take place. No significant positive impact on plasma properties, as reported from other tokamak devices, could be found; the Li pellets rather caused a small reduction in plasma energy, mainly due to enhanced radiation. Due to pellet injection, a short-lived Li layer was formed on the plasma-facing components, which lasted a few discharges and led to moderately beneficial effects during plasma start-up. Most pellets were found to trigger type-I ELMs, either by their direct local perturbation or indirectly by the altered edge conditions; however, reliability was less than 100%.

    KW - confinement

    KW - ELMs

    KW - Li pellets

    KW - plasma facing components

    KW - tokamak ASDEX upgrade

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    Lang PT, Maingi R, Mansfield DK, McDermott RM, Neu R, Wolfrum E et al. Impact of lithium pellets on plasma performance in the ASDEX Upgrade all-metal-wall tokamak. Nuclear Fusion. 2017 Jan 1;57(1). 016030. https://doi.org/10.1088/0029-5515/57/1/016030