Discriminating the role of rotation and its gradient in determining ion stiffness mitigation in JET

JET-EFDA collaborators

    Research output: Contribution to journalArticleScientificpeer-review

    2 Citations (Scopus)

    Abstract

    Starting from recent JET experimental results that show a significant reduction of ion stiffness in the plasma core region due to plasma rotation in the presence of low magnetic shear, an experiment was carried out at JET in order to separate the role of rotation and rotation gradient in mitigating the ion stiffness level. Enhanced toroidal field ripple (up to 1.5%) and external resonant magnetic fields are the two mechanisms used to try and decouple the rotation value from its gradient. In addition, shots with reversed toroidal field and plasma current, yielding counter-current neutral beam injection, were compared with standard co-injection cases. These tools also allowed varying the rotation independently of the injected power. Shots with high rotation gradient are found to maintain their low stiffness level even when the absolute value of the rotation was significantly reduced. Conversely, high but flat rotation yields much less peaked ion temperature profiles than a peaked rotation profile with lower values. This behaviour suggests the rotation gradient as the main player in reducing the ion stiffness level. In addition, it is found that inverting the rotation gradient sign does not suppress its effect on ion stiffness.
    Original languageEnglish
    Article number025010
    Number of pages7
    JournalPlasma Physics and Controlled Fusion
    Volume55
    Issue number2
    DOIs
    Publication statusPublished - 2013
    MoE publication typeA1 Journal article-refereed

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    stiffness
    Stiffness
    gradients
    Ions
    ions
    Plasmas
    shot
    beam injection
    plasma currents
    neutral beams
    ion temperature
    ripples
    temperature profiles
    counters
    injection
    Magnetic fields
    shear
    profiles
    magnetic fields

    Cite this

    @article{c19a2d86779840cba1eb2d0813c2609c,
    title = "Discriminating the role of rotation and its gradient in determining ion stiffness mitigation in JET",
    abstract = "Starting from recent JET experimental results that show a significant reduction of ion stiffness in the plasma core region due to plasma rotation in the presence of low magnetic shear, an experiment was carried out at JET in order to separate the role of rotation and rotation gradient in mitigating the ion stiffness level. Enhanced toroidal field ripple (up to 1.5{\%}) and external resonant magnetic fields are the two mechanisms used to try and decouple the rotation value from its gradient. In addition, shots with reversed toroidal field and plasma current, yielding counter-current neutral beam injection, were compared with standard co-injection cases. These tools also allowed varying the rotation independently of the injected power. Shots with high rotation gradient are found to maintain their low stiffness level even when the absolute value of the rotation was significantly reduced. Conversely, high but flat rotation yields much less peaked ion temperature profiles than a peaked rotation profile with lower values. This behaviour suggests the rotation gradient as the main player in reducing the ion stiffness level. In addition, it is found that inverting the rotation gradient sign does not suppress its effect on ion stiffness.",
    author = "B. Baiocchi and P. Mantica and C. Giroud and T. Johnson and V. Naulin and Antti Salmi and Tuomas Tala and M. Tsalas and {JET-EFDA collaborators}",
    year = "2013",
    doi = "10.1088/0741-3335/55/2/025010",
    language = "English",
    volume = "55",
    journal = "Plasma Physics and Controlled Fusion",
    issn = "0741-3335",
    publisher = "Institute of Physics IOP",
    number = "2",

    }

    Discriminating the role of rotation and its gradient in determining ion stiffness mitigation in JET. / JET-EFDA collaborators.

    In: Plasma Physics and Controlled Fusion, Vol. 55, No. 2, 025010, 2013.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Discriminating the role of rotation and its gradient in determining ion stiffness mitigation in JET

    AU - Baiocchi, B.

    AU - Mantica, P.

    AU - Giroud, C.

    AU - Johnson, T.

    AU - Naulin, V.

    AU - Salmi, Antti

    AU - Tala, Tuomas

    AU - Tsalas, M.

    AU - JET-EFDA collaborators

    PY - 2013

    Y1 - 2013

    N2 - Starting from recent JET experimental results that show a significant reduction of ion stiffness in the plasma core region due to plasma rotation in the presence of low magnetic shear, an experiment was carried out at JET in order to separate the role of rotation and rotation gradient in mitigating the ion stiffness level. Enhanced toroidal field ripple (up to 1.5%) and external resonant magnetic fields are the two mechanisms used to try and decouple the rotation value from its gradient. In addition, shots with reversed toroidal field and plasma current, yielding counter-current neutral beam injection, were compared with standard co-injection cases. These tools also allowed varying the rotation independently of the injected power. Shots with high rotation gradient are found to maintain their low stiffness level even when the absolute value of the rotation was significantly reduced. Conversely, high but flat rotation yields much less peaked ion temperature profiles than a peaked rotation profile with lower values. This behaviour suggests the rotation gradient as the main player in reducing the ion stiffness level. In addition, it is found that inverting the rotation gradient sign does not suppress its effect on ion stiffness.

    AB - Starting from recent JET experimental results that show a significant reduction of ion stiffness in the plasma core region due to plasma rotation in the presence of low magnetic shear, an experiment was carried out at JET in order to separate the role of rotation and rotation gradient in mitigating the ion stiffness level. Enhanced toroidal field ripple (up to 1.5%) and external resonant magnetic fields are the two mechanisms used to try and decouple the rotation value from its gradient. In addition, shots with reversed toroidal field and plasma current, yielding counter-current neutral beam injection, were compared with standard co-injection cases. These tools also allowed varying the rotation independently of the injected power. Shots with high rotation gradient are found to maintain their low stiffness level even when the absolute value of the rotation was significantly reduced. Conversely, high but flat rotation yields much less peaked ion temperature profiles than a peaked rotation profile with lower values. This behaviour suggests the rotation gradient as the main player in reducing the ion stiffness level. In addition, it is found that inverting the rotation gradient sign does not suppress its effect on ion stiffness.

    U2 - 10.1088/0741-3335/55/2/025010

    DO - 10.1088/0741-3335/55/2/025010

    M3 - Article

    VL - 55

    JO - Plasma Physics and Controlled Fusion

    JF - Plasma Physics and Controlled Fusion

    SN - 0741-3335

    IS - 2

    M1 - 025010

    ER -