Improved confinement in JET hybrid discharges

JET-EFDA collaborators

    Research output: Contribution to journalArticleScientificpeer-review

    48 Citations (Scopus)

    Abstract

    A new technique has been developed to produce plasmas with improved confinement relative to the H98,y2 scaling law (ITER Physics Expert Groups on Confinement and Transport and Confinement Modelling and Database ITER Physics Basics Editors and ITER EDA 1999 Nucl. Fusion 39 2175) on the JET tokamak. In the mid-size tokamaks ASDEX upgrade and DIII-D heating during the current formation is used to produce a flat q-profile with a minimum close to 1. On JET this technique leads to q-profiles with similar minimum q but opposite to the other tokamaks not to an improved confinement state. By changing the method utilizing a faster current ramp with temporary higher current than in the flattop (current overshoot) plasmas with improved confinement (H98,y2 = 1.35) and good stability (βN ≈ 3) have been produced and extended to many confinement times only limited by technical constraints. The increase in H98,y2-factor is stronger with more heating power as can be seen in a power scan. The q-profile development during the high power phase in JET is reproduced by current diffusion calculated by TRANSP and CRONOS. Therefore the modifications produced by the current overshoot disappear quickly from the edge but the confinement improvement lasts longer, in some cases up to the end of the heating phase.
    Original languageEnglish
    Article number095001
    JournalPlasma Physics and Controlled Fusion
    Volume54
    Issue number9
    DOIs
    Publication statusPublished - 2012
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    Plasma confinement
    Heating
    Physics
    Plasmas
    Scaling laws
    Fusion reactions
    heating
    profiles
    physics
    plasma currents
    ramps
    scaling laws
    high current
    fusion

    Cite this

    JET-EFDA collaborators. / Improved confinement in JET hybrid discharges. In: Plasma Physics and Controlled Fusion. 2012 ; Vol. 54, No. 9.
    @article{2e5fd374f87e460f97cf20ccb87b5085,
    title = "Improved confinement in JET hybrid discharges",
    abstract = "A new technique has been developed to produce plasmas with improved confinement relative to the H98,y2 scaling law (ITER Physics Expert Groups on Confinement and Transport and Confinement Modelling and Database ITER Physics Basics Editors and ITER EDA 1999 Nucl. Fusion 39 2175) on the JET tokamak. In the mid-size tokamaks ASDEX upgrade and DIII-D heating during the current formation is used to produce a flat q-profile with a minimum close to 1. On JET this technique leads to q-profiles with similar minimum q but opposite to the other tokamaks not to an improved confinement state. By changing the method utilizing a faster current ramp with temporary higher current than in the flattop (current overshoot) plasmas with improved confinement (H98,y2 = 1.35) and good stability (βN ≈ 3) have been produced and extended to many confinement times only limited by technical constraints. The increase in H98,y2-factor is stronger with more heating power as can be seen in a power scan. The q-profile development during the high power phase in JET is reproduced by current diffusion calculated by TRANSP and CRONOS. Therefore the modifications produced by the current overshoot disappear quickly from the edge but the confinement improvement lasts longer, in some cases up to the end of the heating phase.",
    author = "J. Hobirk and F. Imbeaux and F. Crisanti and Tuomas Tala and {JET-EFDA collaborators}",
    year = "2012",
    doi = "10.1088/0741-3335/54/9/095001",
    language = "English",
    volume = "54",
    journal = "Plasma Physics and Controlled Fusion",
    issn = "0741-3335",
    publisher = "Institute of Physics IOP",
    number = "9",

    }

    Improved confinement in JET hybrid discharges. / JET-EFDA collaborators.

    In: Plasma Physics and Controlled Fusion, Vol. 54, No. 9, 095001, 2012.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Improved confinement in JET hybrid discharges

    AU - Hobirk, J.

    AU - Imbeaux, F.

    AU - Crisanti, F.

    AU - Tala, Tuomas

    AU - JET-EFDA collaborators

    PY - 2012

    Y1 - 2012

    N2 - A new technique has been developed to produce plasmas with improved confinement relative to the H98,y2 scaling law (ITER Physics Expert Groups on Confinement and Transport and Confinement Modelling and Database ITER Physics Basics Editors and ITER EDA 1999 Nucl. Fusion 39 2175) on the JET tokamak. In the mid-size tokamaks ASDEX upgrade and DIII-D heating during the current formation is used to produce a flat q-profile with a minimum close to 1. On JET this technique leads to q-profiles with similar minimum q but opposite to the other tokamaks not to an improved confinement state. By changing the method utilizing a faster current ramp with temporary higher current than in the flattop (current overshoot) plasmas with improved confinement (H98,y2 = 1.35) and good stability (βN ≈ 3) have been produced and extended to many confinement times only limited by technical constraints. The increase in H98,y2-factor is stronger with more heating power as can be seen in a power scan. The q-profile development during the high power phase in JET is reproduced by current diffusion calculated by TRANSP and CRONOS. Therefore the modifications produced by the current overshoot disappear quickly from the edge but the confinement improvement lasts longer, in some cases up to the end of the heating phase.

    AB - A new technique has been developed to produce plasmas with improved confinement relative to the H98,y2 scaling law (ITER Physics Expert Groups on Confinement and Transport and Confinement Modelling and Database ITER Physics Basics Editors and ITER EDA 1999 Nucl. Fusion 39 2175) on the JET tokamak. In the mid-size tokamaks ASDEX upgrade and DIII-D heating during the current formation is used to produce a flat q-profile with a minimum close to 1. On JET this technique leads to q-profiles with similar minimum q but opposite to the other tokamaks not to an improved confinement state. By changing the method utilizing a faster current ramp with temporary higher current than in the flattop (current overshoot) plasmas with improved confinement (H98,y2 = 1.35) and good stability (βN ≈ 3) have been produced and extended to many confinement times only limited by technical constraints. The increase in H98,y2-factor is stronger with more heating power as can be seen in a power scan. The q-profile development during the high power phase in JET is reproduced by current diffusion calculated by TRANSP and CRONOS. Therefore the modifications produced by the current overshoot disappear quickly from the edge but the confinement improvement lasts longer, in some cases up to the end of the heating phase.

    U2 - 10.1088/0741-3335/54/9/095001

    DO - 10.1088/0741-3335/54/9/095001

    M3 - Article

    VL - 54

    JO - Plasma Physics and Controlled Fusion

    JF - Plasma Physics and Controlled Fusion

    SN - 0741-3335

    IS - 9

    M1 - 095001

    ER -