ITB formation in terms of wExB flow shear and magnetic shear s on JET

Tuomas Tala, Jukka Heikkinen, V. Parail

    Research output: Contribution to journalArticleScientificpeer-review

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    Abstract

    A linear empirical threshold condition ωExBITG>0.68s-0.095 has been found for the onset of the ion internal transport barriers in the JET optimised shear database. Here, s is the magnetic shear, ωExB the flow shearing rate and γITG is an approximate of the linear growth rate of the ion temperature gradient instability. The present empirical threshold condition for the ITB formation will provide a first clear indication of the strong correlation of s and ωExB at the ITB transition. The empirical analysis consists of ITB discharges from a wide plasma parameter range; the toroidal magnetic field varies between 1.8-4.0 T, the auxiliary heating power between 10-30 MW and the diamagnetic energy between 3-12 MJ. The predictive simulations of several ITB discharges with the empirical ITB threshold condition reproduce the experiments with time averaged prediction errors of the order of 10-25% in Ti and Te profiles and 10-15% in ne profiles as well as the toroidal flow velocity with errors of the order of 10-20%. The simulated times of the onset of the ITB compared to the experimental ones are typically within 0.4 s and the simulated ITB widths within 0.1 in r/a throughout the whole simulations.
    Original languageEnglish
    Pages (from-to)507-523
    Number of pages17
    JournalPlasma Physics and Controlled Fusion
    Volume43
    Issue number4
    Publication statusPublished - 2001
    MoE publication typeA1 Journal article-refereed

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    Shear flow
    shear flow
    shear
    thresholds
    Ions
    Shearing
    Flow velocity
    Thermal gradients
    Magnetic fields
    ion temperature
    profiles
    shearing
    Plasmas
    Heating
    temperature gradients
    indication
    simulation
    flow velocity
    heating
    Experiments

    Cite this

    Tala, Tuomas ; Heikkinen, Jukka ; Parail, V. / ITB formation in terms of wExB flow shear and magnetic shear s on JET. In: Plasma Physics and Controlled Fusion. 2001 ; Vol. 43, No. 4. pp. 507-523.
    @article{083789b828144b79a472904441bda379,
    title = "ITB formation in terms of wExB flow shear and magnetic shear s on JET",
    abstract = "A linear empirical threshold condition ωExB/γITG>0.68s-0.095 has been found for the onset of the ion internal transport barriers in the JET optimised shear database. Here, s is the magnetic shear, ωExB the flow shearing rate and γITG is an approximate of the linear growth rate of the ion temperature gradient instability. The present empirical threshold condition for the ITB formation will provide a first clear indication of the strong correlation of s and ωExB at the ITB transition. The empirical analysis consists of ITB discharges from a wide plasma parameter range; the toroidal magnetic field varies between 1.8-4.0 T, the auxiliary heating power between 10-30 MW and the diamagnetic energy between 3-12 MJ. The predictive simulations of several ITB discharges with the empirical ITB threshold condition reproduce the experiments with time averaged prediction errors of the order of 10-25{\%} in Ti and Te profiles and 10-15{\%} in ne profiles as well as the toroidal flow velocity with errors of the order of 10-20{\%}. The simulated times of the onset of the ITB compared to the experimental ones are typically within 0.4 s and the simulated ITB widths within 0.1 in r/a throughout the whole simulations.",
    author = "Tuomas Tala and Jukka Heikkinen and V. Parail",
    year = "2001",
    language = "English",
    volume = "43",
    pages = "507--523",
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    ITB formation in terms of wExB flow shear and magnetic shear s on JET. / Tala, Tuomas; Heikkinen, Jukka; Parail, V.

    In: Plasma Physics and Controlled Fusion, Vol. 43, No. 4, 2001, p. 507-523.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - ITB formation in terms of wExB flow shear and magnetic shear s on JET

    AU - Tala, Tuomas

    AU - Heikkinen, Jukka

    AU - Parail, V.

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    N2 - A linear empirical threshold condition ωExB/γITG>0.68s-0.095 has been found for the onset of the ion internal transport barriers in the JET optimised shear database. Here, s is the magnetic shear, ωExB the flow shearing rate and γITG is an approximate of the linear growth rate of the ion temperature gradient instability. The present empirical threshold condition for the ITB formation will provide a first clear indication of the strong correlation of s and ωExB at the ITB transition. The empirical analysis consists of ITB discharges from a wide plasma parameter range; the toroidal magnetic field varies between 1.8-4.0 T, the auxiliary heating power between 10-30 MW and the diamagnetic energy between 3-12 MJ. The predictive simulations of several ITB discharges with the empirical ITB threshold condition reproduce the experiments with time averaged prediction errors of the order of 10-25% in Ti and Te profiles and 10-15% in ne profiles as well as the toroidal flow velocity with errors of the order of 10-20%. The simulated times of the onset of the ITB compared to the experimental ones are typically within 0.4 s and the simulated ITB widths within 0.1 in r/a throughout the whole simulations.

    AB - A linear empirical threshold condition ωExB/γITG>0.68s-0.095 has been found for the onset of the ion internal transport barriers in the JET optimised shear database. Here, s is the magnetic shear, ωExB the flow shearing rate and γITG is an approximate of the linear growth rate of the ion temperature gradient instability. The present empirical threshold condition for the ITB formation will provide a first clear indication of the strong correlation of s and ωExB at the ITB transition. The empirical analysis consists of ITB discharges from a wide plasma parameter range; the toroidal magnetic field varies between 1.8-4.0 T, the auxiliary heating power between 10-30 MW and the diamagnetic energy between 3-12 MJ. The predictive simulations of several ITB discharges with the empirical ITB threshold condition reproduce the experiments with time averaged prediction errors of the order of 10-25% in Ti and Te profiles and 10-15% in ne profiles as well as the toroidal flow velocity with errors of the order of 10-20%. The simulated times of the onset of the ITB compared to the experimental ones are typically within 0.4 s and the simulated ITB widths within 0.1 in r/a throughout the whole simulations.

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