Impact of different heating and current drive methods on the early shape q-profile evolution in JET

Tuomas Tala (Corresponding Author), V. Parail, A. Becoulet, C. Challis, G. Corrigan, N. Hawkes, D. Heading, M. Mantsinen, S. Nowak, Contributors to the EFDA-JET Work Programme

    Research output: Contribution to journalArticleScientificpeer-review

    15 Citations (Scopus)

    Abstract

    Transport calculations illustrate that the lower hybrid current drive (LHCD) and off-axis electron cyclotron current drive (ECCD) are the only preheating methods that can create a wide, deeply reversed q-profile, i.e. large negative magnetic shear, on the JET tokamak. Off-axis neutral beam injection (NBI) and off-axis ion cyclotron resonance heating (ICRH) preheating yields a weakly reversed q-profile (small negative magnetic shear), whereas NBI and ICRH on-axis heating as well as ohmic preheating produce a monotonic q-profile in the preheating phase. Here, on-axis power deposition and current drive refers to heating and current drive at or close to magnetic axis and correspondingly, off-axis refers to heating and current drive deposited typically around the half minor radius (r/a = 0.3-0.6). The results on LHCD, ICRH and ohmic preheating have been verified in the recent JET experiments. The current drive efficiency scan shows that in the case of LHCD, ECCD and off-axis NBI, the driven current is absolutely crucial to obtain a reversed q-profile and to modify the current profile evolution drastically in the preheating phase. Taking into account only the direct electron heating effect, LHCD does not create a reversed q-profile. The timing scans indicate that the radial location of qmin at the end of the preheating phase is generally quite insensitive to the start time of the preheating, once started 0-2 s after the plasma initiation if the method relies upon the driven current. On the other hand, methods relying only upon electron heating are very sensitive to that. In both cases, the magnitude of the negative magnetic shear, however, seems to be very sensitive to the start time of the preheating.
    Original languageEnglish
    Pages (from-to)1181-1202
    JournalPlasma Physics and Controlled Fusion
    Volume44
    Issue number7
    DOIs
    Publication statusPublished - 2002
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    Preheating
    Heating
    heating
    profiles
    Cyclotron resonance
    Electrons
    Cyclotrons
    beam injection
    neutral beams
    cyclotron resonance
    Ions
    shear
    Joule heating
    cyclotrons
    electrons
    ions
    Plasmas

    Keywords

    • JET
    • plasma
    • fusion energy
    • fusion reactors
    • tokamak
    • internal transport barriers
    • lower hybrid current drive
    • magnetic shear

    Cite this

    Tala, T., Parail, V., Becoulet, A., Challis, C., Corrigan, G., Hawkes, N., ... Programme, C. T. T. EFDA-JET. W. (2002). Impact of different heating and current drive methods on the early shape q-profile evolution in JET. Plasma Physics and Controlled Fusion, 44(7), 1181-1202. https://doi.org/10.1088/0741-3335/44/7/309
    Tala, Tuomas ; Parail, V. ; Becoulet, A. ; Challis, C. ; Corrigan, G. ; Hawkes, N. ; Heading, D. ; Mantsinen, M. ; Nowak, S. ; Programme, Contributors to the EFDA-JET Work. / Impact of different heating and current drive methods on the early shape q-profile evolution in JET. In: Plasma Physics and Controlled Fusion. 2002 ; Vol. 44, No. 7. pp. 1181-1202.
    @article{bd156a7325db430b84664ce6f4070b48,
    title = "Impact of different heating and current drive methods on the early shape q-profile evolution in JET",
    abstract = "Transport calculations illustrate that the lower hybrid current drive (LHCD) and off-axis electron cyclotron current drive (ECCD) are the only preheating methods that can create a wide, deeply reversed q-profile, i.e. large negative magnetic shear, on the JET tokamak. Off-axis neutral beam injection (NBI) and off-axis ion cyclotron resonance heating (ICRH) preheating yields a weakly reversed q-profile (small negative magnetic shear), whereas NBI and ICRH on-axis heating as well as ohmic preheating produce a monotonic q-profile in the preheating phase. Here, on-axis power deposition and current drive refers to heating and current drive at or close to magnetic axis and correspondingly, off-axis refers to heating and current drive deposited typically around the half minor radius (r/a = 0.3-0.6). The results on LHCD, ICRH and ohmic preheating have been verified in the recent JET experiments. The current drive efficiency scan shows that in the case of LHCD, ECCD and off-axis NBI, the driven current is absolutely crucial to obtain a reversed q-profile and to modify the current profile evolution drastically in the preheating phase. Taking into account only the direct electron heating effect, LHCD does not create a reversed q-profile. The timing scans indicate that the radial location of qmin at the end of the preheating phase is generally quite insensitive to the start time of the preheating, once started 0-2 s after the plasma initiation if the method relies upon the driven current. On the other hand, methods relying only upon electron heating are very sensitive to that. In both cases, the magnitude of the negative magnetic shear, however, seems to be very sensitive to the start time of the preheating.",
    keywords = "JET, plasma, fusion energy, fusion reactors, tokamak, internal transport barriers, lower hybrid current drive, magnetic shear",
    author = "Tuomas Tala and V. Parail and A. Becoulet and C. Challis and G. Corrigan and N. Hawkes and D. Heading and M. Mantsinen and S. Nowak and Programme, {Contributors to the EFDA-JET Work}",
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    Tala, T, Parail, V, Becoulet, A, Challis, C, Corrigan, G, Hawkes, N, Heading, D, Mantsinen, M, Nowak, S & Programme, CTTEFDA-JETW 2002, 'Impact of different heating and current drive methods on the early shape q-profile evolution in JET', Plasma Physics and Controlled Fusion, vol. 44, no. 7, pp. 1181-1202. https://doi.org/10.1088/0741-3335/44/7/309

    Impact of different heating and current drive methods on the early shape q-profile evolution in JET. / Tala, Tuomas (Corresponding Author); Parail, V.; Becoulet, A.; Challis, C.; Corrigan, G.; Hawkes, N.; Heading, D.; Mantsinen, M.; Nowak, S.; Programme, Contributors to the EFDA-JET Work.

    In: Plasma Physics and Controlled Fusion, Vol. 44, No. 7, 2002, p. 1181-1202.

    Research output: Contribution to journalArticleScientificpeer-review

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    T1 - Impact of different heating and current drive methods on the early shape q-profile evolution in JET

    AU - Tala, Tuomas

    AU - Parail, V.

    AU - Becoulet, A.

    AU - Challis, C.

    AU - Corrigan, G.

    AU - Hawkes, N.

    AU - Heading, D.

    AU - Mantsinen, M.

    AU - Nowak, S.

    AU - Programme, Contributors to the EFDA-JET Work

    PY - 2002

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    N2 - Transport calculations illustrate that the lower hybrid current drive (LHCD) and off-axis electron cyclotron current drive (ECCD) are the only preheating methods that can create a wide, deeply reversed q-profile, i.e. large negative magnetic shear, on the JET tokamak. Off-axis neutral beam injection (NBI) and off-axis ion cyclotron resonance heating (ICRH) preheating yields a weakly reversed q-profile (small negative magnetic shear), whereas NBI and ICRH on-axis heating as well as ohmic preheating produce a monotonic q-profile in the preheating phase. Here, on-axis power deposition and current drive refers to heating and current drive at or close to magnetic axis and correspondingly, off-axis refers to heating and current drive deposited typically around the half minor radius (r/a = 0.3-0.6). The results on LHCD, ICRH and ohmic preheating have been verified in the recent JET experiments. The current drive efficiency scan shows that in the case of LHCD, ECCD and off-axis NBI, the driven current is absolutely crucial to obtain a reversed q-profile and to modify the current profile evolution drastically in the preheating phase. Taking into account only the direct electron heating effect, LHCD does not create a reversed q-profile. The timing scans indicate that the radial location of qmin at the end of the preheating phase is generally quite insensitive to the start time of the preheating, once started 0-2 s after the plasma initiation if the method relies upon the driven current. On the other hand, methods relying only upon electron heating are very sensitive to that. In both cases, the magnitude of the negative magnetic shear, however, seems to be very sensitive to the start time of the preheating.

    AB - Transport calculations illustrate that the lower hybrid current drive (LHCD) and off-axis electron cyclotron current drive (ECCD) are the only preheating methods that can create a wide, deeply reversed q-profile, i.e. large negative magnetic shear, on the JET tokamak. Off-axis neutral beam injection (NBI) and off-axis ion cyclotron resonance heating (ICRH) preheating yields a weakly reversed q-profile (small negative magnetic shear), whereas NBI and ICRH on-axis heating as well as ohmic preheating produce a monotonic q-profile in the preheating phase. Here, on-axis power deposition and current drive refers to heating and current drive at or close to magnetic axis and correspondingly, off-axis refers to heating and current drive deposited typically around the half minor radius (r/a = 0.3-0.6). The results on LHCD, ICRH and ohmic preheating have been verified in the recent JET experiments. The current drive efficiency scan shows that in the case of LHCD, ECCD and off-axis NBI, the driven current is absolutely crucial to obtain a reversed q-profile and to modify the current profile evolution drastically in the preheating phase. Taking into account only the direct electron heating effect, LHCD does not create a reversed q-profile. The timing scans indicate that the radial location of qmin at the end of the preheating phase is generally quite insensitive to the start time of the preheating, once started 0-2 s after the plasma initiation if the method relies upon the driven current. On the other hand, methods relying only upon electron heating are very sensitive to that. In both cases, the magnitude of the negative magnetic shear, however, seems to be very sensitive to the start time of the preheating.

    KW - JET

    KW - plasma

    KW - fusion energy

    KW - fusion reactors

    KW - tokamak

    KW - internal transport barriers

    KW - lower hybrid current drive

    KW - magnetic shear

    U2 - 10.1088/0741-3335/44/7/309

    DO - 10.1088/0741-3335/44/7/309

    M3 - Article

    VL - 44

    SP - 1181

    EP - 1202

    JO - Plasma Physics and Controlled Fusion

    JF - Plasma Physics and Controlled Fusion

    SN - 0741-3335

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    ER -