Outer divertor of ASDEX Upgrade in low-density L-mode discharges in forward and reversed magnetic field: II: Analysis of local impurity migration

Leena Aho-Mantila (Corresponding Author), M. Wischmeier, K. Krieger, V. Rohde, Antti Hakola, S. Potzel, A. Kirschner, D. Borodin, ASDEX Upgrade Team

    Research output: Contribution to journalArticleScientificpeer-review

    9 Citations (Scopus)

    Abstract

    Part I (Aho-Mantila L. et al 2012 Nucl. Fusion 52 103006) presented a detailed analysis of outer divertor plasma conditions in low-density L-mode discharges in ASDEX Upgrade. In this paper, we analyse the local migration of carbon that originates from 13CH4 injected into these plasmas from the vertical outer target. Notable changes are observed in the local carbon deposition patterns when reversing the magnetic field in the experiments. Kinetic impurity-following simulations are performed using the 3D ERO code package with 2D background plasma solutions calculated with the SOLPS5.0 code package. The modelling shows that the measured changes are due to the changes in plasma collisionality, dissociation and ionization rates, and E × B drift of the impurities. These conditions affect the direction and rate of impurity migration inside and out of the divertor, having wider consequences on the global migration of impurities in a divertor tokamak. It is further shown that the migration pathways are largely determined by carbon ions and, hence, relevant for impurities in general. Neutral carbon and hydrocarbons are deposited only in the near vicinity of the injection, where they affect the local re-deposition efficiency. In this limited region, a perturbation of the local plasma conditions by the methane puff appears likely, yielding a significant uncertainty for interpreting the deposition efficiencies. The local deposition is largely influenced by the magnetic presheath electric field, the structure of which is the main uncertainty in the SOLPS5.0-ERO simulations.
    Original languageEnglish
    Article number103007
    Number of pages13
    JournalNuclear Fusion
    Volume52
    Issue number10
    DOIs
    Publication statusPublished - 2012
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    impurities
    magnetic fields
    carbon
    reversing
    methane
    simulation
    hydrocarbons
    fusion
    dissociation
    injection
    ionization
    perturbation
    electric fields
    kinetics
    ions

    Cite this

    Aho-Mantila, Leena ; Wischmeier, M. ; Krieger, K. ; Rohde, V. ; Hakola, Antti ; Potzel, S. ; Kirschner, A. ; Borodin, D. ; ASDEX Upgrade Team. / Outer divertor of ASDEX Upgrade in low-density L-mode discharges in forward and reversed magnetic field: II : Analysis of local impurity migration. In: Nuclear Fusion. 2012 ; Vol. 52, No. 10.
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    abstract = "Part I (Aho-Mantila L. et al 2012 Nucl. Fusion 52 103006) presented a detailed analysis of outer divertor plasma conditions in low-density L-mode discharges in ASDEX Upgrade. In this paper, we analyse the local migration of carbon that originates from 13CH4 injected into these plasmas from the vertical outer target. Notable changes are observed in the local carbon deposition patterns when reversing the magnetic field in the experiments. Kinetic impurity-following simulations are performed using the 3D ERO code package with 2D background plasma solutions calculated with the SOLPS5.0 code package. The modelling shows that the measured changes are due to the changes in plasma collisionality, dissociation and ionization rates, and E × B drift of the impurities. These conditions affect the direction and rate of impurity migration inside and out of the divertor, having wider consequences on the global migration of impurities in a divertor tokamak. It is further shown that the migration pathways are largely determined by carbon ions and, hence, relevant for impurities in general. Neutral carbon and hydrocarbons are deposited only in the near vicinity of the injection, where they affect the local re-deposition efficiency. In this limited region, a perturbation of the local plasma conditions by the methane puff appears likely, yielding a significant uncertainty for interpreting the deposition efficiencies. The local deposition is largely influenced by the magnetic presheath electric field, the structure of which is the main uncertainty in the SOLPS5.0-ERO simulations.",
    author = "Leena Aho-Mantila and M. Wischmeier and K. Krieger and V. Rohde and Antti Hakola and S. Potzel and A. Kirschner and D. Borodin and {ASDEX Upgrade Team}",
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    language = "English",
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    Outer divertor of ASDEX Upgrade in low-density L-mode discharges in forward and reversed magnetic field: II : Analysis of local impurity migration. / Aho-Mantila, Leena (Corresponding Author); Wischmeier, M.; Krieger, K.; Rohde, V.; Hakola, Antti; Potzel, S.; Kirschner, A.; Borodin, D.; ASDEX Upgrade Team.

    In: Nuclear Fusion, Vol. 52, No. 10, 103007, 2012.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Outer divertor of ASDEX Upgrade in low-density L-mode discharges in forward and reversed magnetic field: II

    T2 - Analysis of local impurity migration

    AU - Aho-Mantila, Leena

    AU - Wischmeier, M.

    AU - Krieger, K.

    AU - Rohde, V.

    AU - Hakola, Antti

    AU - Potzel, S.

    AU - Kirschner, A.

    AU - Borodin, D.

    AU - ASDEX Upgrade Team

    PY - 2012

    Y1 - 2012

    N2 - Part I (Aho-Mantila L. et al 2012 Nucl. Fusion 52 103006) presented a detailed analysis of outer divertor plasma conditions in low-density L-mode discharges in ASDEX Upgrade. In this paper, we analyse the local migration of carbon that originates from 13CH4 injected into these plasmas from the vertical outer target. Notable changes are observed in the local carbon deposition patterns when reversing the magnetic field in the experiments. Kinetic impurity-following simulations are performed using the 3D ERO code package with 2D background plasma solutions calculated with the SOLPS5.0 code package. The modelling shows that the measured changes are due to the changes in plasma collisionality, dissociation and ionization rates, and E × B drift of the impurities. These conditions affect the direction and rate of impurity migration inside and out of the divertor, having wider consequences on the global migration of impurities in a divertor tokamak. It is further shown that the migration pathways are largely determined by carbon ions and, hence, relevant for impurities in general. Neutral carbon and hydrocarbons are deposited only in the near vicinity of the injection, where they affect the local re-deposition efficiency. In this limited region, a perturbation of the local plasma conditions by the methane puff appears likely, yielding a significant uncertainty for interpreting the deposition efficiencies. The local deposition is largely influenced by the magnetic presheath electric field, the structure of which is the main uncertainty in the SOLPS5.0-ERO simulations.

    AB - Part I (Aho-Mantila L. et al 2012 Nucl. Fusion 52 103006) presented a detailed analysis of outer divertor plasma conditions in low-density L-mode discharges in ASDEX Upgrade. In this paper, we analyse the local migration of carbon that originates from 13CH4 injected into these plasmas from the vertical outer target. Notable changes are observed in the local carbon deposition patterns when reversing the magnetic field in the experiments. Kinetic impurity-following simulations are performed using the 3D ERO code package with 2D background plasma solutions calculated with the SOLPS5.0 code package. The modelling shows that the measured changes are due to the changes in plasma collisionality, dissociation and ionization rates, and E × B drift of the impurities. These conditions affect the direction and rate of impurity migration inside and out of the divertor, having wider consequences on the global migration of impurities in a divertor tokamak. It is further shown that the migration pathways are largely determined by carbon ions and, hence, relevant for impurities in general. Neutral carbon and hydrocarbons are deposited only in the near vicinity of the injection, where they affect the local re-deposition efficiency. In this limited region, a perturbation of the local plasma conditions by the methane puff appears likely, yielding a significant uncertainty for interpreting the deposition efficiencies. The local deposition is largely influenced by the magnetic presheath electric field, the structure of which is the main uncertainty in the SOLPS5.0-ERO simulations.

    U2 - 10.1088/0029-5515/52/10/103007

    DO - 10.1088/0029-5515/52/10/103007

    M3 - Article

    VL - 52

    JO - Nuclear Fusion

    JF - Nuclear Fusion

    SN - 0029-5515

    IS - 10

    M1 - 103007

    ER -