A path to stable low-torque plasma operation in ITER with test blanket modules

M. Lanctot, J.A. Snipes, [Unknown] Reimerdes H, C. Paz-Soldan, N. Logan, J.M. Hanson, R,J. Buttery, J. deGrassie, A.M. Garofalo, T.K. Gray, B.A. Grierson, J.D. King, G.J. Kramer, R. La Haye, D.C. Pace, J.K. Park, A. Salmi, S Shiraki, E.J. Strait, W.M. SolomonT. Tala, M.A. Van Zeeland

    Research output: Contribution to journalArticleScientificpeer-review

    5 Citations (Scopus)

    Abstract

    New experiments in the low-torque ITER Q = 10 scenario on DIII-D demonstrate that n = 1 magnetic fields from a single row of ex-vessel control coils enable operation at ITER performance metrics in the presence of applied non-axisymmetric magnetic fields from a test blanket module (TBM) mock-up coil. With n = 1 compensation, operation below the ITER-equivalent injected torque is successful at three times the ITER equivalent toroidal magnetic field ripple for a pair of TBMs in one equatorial port, whereas the uncompensated TBM field leads to rotation collapse, loss of H-mode and plasma current disruption. In companion experiments at high plasma beta, where the n = 1 plasma response is enhanced, uncorrected TBM fields degrade energy confinement and the plasma angular momentum while increasing fast ion losses; however, disruptions are not routinely encountered owing to increased levels of injected neutral beam torque. In this regime, n = 1 field compensation leads to recovery of a dominant fraction of the TBM-induced plasma pressure and rotation degradation, and an 80% reduction in the heat load to the first wall. These results show that the n = 1 plasma response plays a dominant role in determining plasma stability, and that n = 1 field compensation alone not only recovers most of the impact on plasma performance of the TBM, but also protects the first wall from potentially damaging heat flux. Despite these benefits, plasma rotation braking from the TBM fields cannot be fully recovered using standard error field control. Given the uncertainty in extrapolation of these results to the ITER configuration, it is prudent to design the TBMs with as low a ferromagnetic mass as possible without jeopardizing the TBM mission.

    Original languageEnglish
    Article number036004
    JournalNuclear Fusion
    Volume57
    Issue number3
    DOIs
    Publication statusPublished - 2017
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    blankets
    torque
    modules
    coils
    magnetic fields
    plasma pressure
    braking
    magnetohydrodynamic stability
    plasma currents
    neutral beams
    ripples
    vessels
    extrapolation
    heat flux
    angular momentum
    recovery
    degradation
    heat
    configurations
    ions

    Keywords

    • test blanket modules
    • error fields
    • ITER
    • DIII-D

    Cite this

    Lanctot, M., Snipes, J. A., Reimerdes H, U., Paz-Soldan, C., Logan, N., Hanson, J. M., ... Van Zeeland, M. A. (2017). A path to stable low-torque plasma operation in ITER with test blanket modules. Nuclear Fusion, 57(3), [036004]. https://doi.org/10.1088/1741-4326/57/3/036004
    Lanctot, M. ; Snipes, J.A. ; Reimerdes H, [Unknown] ; Paz-Soldan, C. ; Logan, N. ; Hanson, J.M. ; Buttery, R,J. ; deGrassie, J. ; Garofalo, A.M. ; Gray, T.K. ; Grierson, B.A. ; King, J.D. ; Kramer, G.J. ; La Haye, R. ; Pace, D.C. ; Park, J.K. ; Salmi, A. ; Shiraki, S ; Strait, E.J. ; Solomon, W.M. ; Tala, T. ; Van Zeeland, M.A. / A path to stable low-torque plasma operation in ITER with test blanket modules. In: Nuclear Fusion. 2017 ; Vol. 57, No. 3.
    @article{e892fdeeadf84554b5113c736bb2a4f3,
    title = "A path to stable low-torque plasma operation in ITER with test blanket modules",
    abstract = "New experiments in the low-torque ITER Q = 10 scenario on DIII-D demonstrate that n = 1 magnetic fields from a single row of ex-vessel control coils enable operation at ITER performance metrics in the presence of applied non-axisymmetric magnetic fields from a test blanket module (TBM) mock-up coil. With n = 1 compensation, operation below the ITER-equivalent injected torque is successful at three times the ITER equivalent toroidal magnetic field ripple for a pair of TBMs in one equatorial port, whereas the uncompensated TBM field leads to rotation collapse, loss of H-mode and plasma current disruption. In companion experiments at high plasma beta, where the n = 1 plasma response is enhanced, uncorrected TBM fields degrade energy confinement and the plasma angular momentum while increasing fast ion losses; however, disruptions are not routinely encountered owing to increased levels of injected neutral beam torque. In this regime, n = 1 field compensation leads to recovery of a dominant fraction of the TBM-induced plasma pressure and rotation degradation, and an 80{\%} reduction in the heat load to the first wall. These results show that the n = 1 plasma response plays a dominant role in determining plasma stability, and that n = 1 field compensation alone not only recovers most of the impact on plasma performance of the TBM, but also protects the first wall from potentially damaging heat flux. Despite these benefits, plasma rotation braking from the TBM fields cannot be fully recovered using standard error field control. Given the uncertainty in extrapolation of these results to the ITER configuration, it is prudent to design the TBMs with as low a ferromagnetic mass as possible without jeopardizing the TBM mission.",
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    author = "M. Lanctot and J.A. Snipes and {Reimerdes H}, [Unknown] and C. Paz-Soldan and N. Logan and J.M. Hanson and R,J. Buttery and J. deGrassie and A.M. Garofalo and T.K. Gray and B.A. Grierson and J.D. King and G.J. Kramer and {La Haye}, R. and D.C. Pace and J.K. Park and A. Salmi and S Shiraki and E.J. Strait and W.M. Solomon and T. Tala and {Van Zeeland}, M.A.",
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    Lanctot, M, Snipes, JA, Reimerdes H, U, Paz-Soldan, C, Logan, N, Hanson, JM, Buttery, RJ, deGrassie, J, Garofalo, AM, Gray, TK, Grierson, BA, King, JD, Kramer, GJ, La Haye, R, Pace, DC, Park, JK, Salmi, A, Shiraki, S, Strait, EJ, Solomon, WM, Tala, T & Van Zeeland, MA 2017, 'A path to stable low-torque plasma operation in ITER with test blanket modules', Nuclear Fusion, vol. 57, no. 3, 036004. https://doi.org/10.1088/1741-4326/57/3/036004

    A path to stable low-torque plasma operation in ITER with test blanket modules. / Lanctot, M.; Snipes, J.A.; Reimerdes H, [Unknown]; Paz-Soldan, C.; Logan, N.; Hanson, J.M.; Buttery, R,J.; deGrassie, J.; Garofalo, A.M.; Gray, T.K.; Grierson, B.A.; King, J.D.; Kramer, G.J.; La Haye, R.; Pace, D.C.; Park, J.K.; Salmi, A.; Shiraki, S; Strait, E.J.; Solomon, W.M.; Tala, T.; Van Zeeland, M.A.

    In: Nuclear Fusion, Vol. 57, No. 3, 036004, 2017.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - A path to stable low-torque plasma operation in ITER with test blanket modules

    AU - Lanctot, M.

    AU - Snipes, J.A.

    AU - Reimerdes H, [Unknown]

    AU - Paz-Soldan, C.

    AU - Logan, N.

    AU - Hanson, J.M.

    AU - Buttery, R,J.

    AU - deGrassie, J.

    AU - Garofalo, A.M.

    AU - Gray, T.K.

    AU - Grierson, B.A.

    AU - King, J.D.

    AU - Kramer, G.J.

    AU - La Haye, R.

    AU - Pace, D.C.

    AU - Park, J.K.

    AU - Salmi, A.

    AU - Shiraki, S

    AU - Strait, E.J.

    AU - Solomon, W.M.

    AU - Tala, T.

    AU - Van Zeeland, M.A.

    PY - 2017

    Y1 - 2017

    N2 - New experiments in the low-torque ITER Q = 10 scenario on DIII-D demonstrate that n = 1 magnetic fields from a single row of ex-vessel control coils enable operation at ITER performance metrics in the presence of applied non-axisymmetric magnetic fields from a test blanket module (TBM) mock-up coil. With n = 1 compensation, operation below the ITER-equivalent injected torque is successful at three times the ITER equivalent toroidal magnetic field ripple for a pair of TBMs in one equatorial port, whereas the uncompensated TBM field leads to rotation collapse, loss of H-mode and plasma current disruption. In companion experiments at high plasma beta, where the n = 1 plasma response is enhanced, uncorrected TBM fields degrade energy confinement and the plasma angular momentum while increasing fast ion losses; however, disruptions are not routinely encountered owing to increased levels of injected neutral beam torque. In this regime, n = 1 field compensation leads to recovery of a dominant fraction of the TBM-induced plasma pressure and rotation degradation, and an 80% reduction in the heat load to the first wall. These results show that the n = 1 plasma response plays a dominant role in determining plasma stability, and that n = 1 field compensation alone not only recovers most of the impact on plasma performance of the TBM, but also protects the first wall from potentially damaging heat flux. Despite these benefits, plasma rotation braking from the TBM fields cannot be fully recovered using standard error field control. Given the uncertainty in extrapolation of these results to the ITER configuration, it is prudent to design the TBMs with as low a ferromagnetic mass as possible without jeopardizing the TBM mission.

    AB - New experiments in the low-torque ITER Q = 10 scenario on DIII-D demonstrate that n = 1 magnetic fields from a single row of ex-vessel control coils enable operation at ITER performance metrics in the presence of applied non-axisymmetric magnetic fields from a test blanket module (TBM) mock-up coil. With n = 1 compensation, operation below the ITER-equivalent injected torque is successful at three times the ITER equivalent toroidal magnetic field ripple for a pair of TBMs in one equatorial port, whereas the uncompensated TBM field leads to rotation collapse, loss of H-mode and plasma current disruption. In companion experiments at high plasma beta, where the n = 1 plasma response is enhanced, uncorrected TBM fields degrade energy confinement and the plasma angular momentum while increasing fast ion losses; however, disruptions are not routinely encountered owing to increased levels of injected neutral beam torque. In this regime, n = 1 field compensation leads to recovery of a dominant fraction of the TBM-induced plasma pressure and rotation degradation, and an 80% reduction in the heat load to the first wall. These results show that the n = 1 plasma response plays a dominant role in determining plasma stability, and that n = 1 field compensation alone not only recovers most of the impact on plasma performance of the TBM, but also protects the first wall from potentially damaging heat flux. Despite these benefits, plasma rotation braking from the TBM fields cannot be fully recovered using standard error field control. Given the uncertainty in extrapolation of these results to the ITER configuration, it is prudent to design the TBMs with as low a ferromagnetic mass as possible without jeopardizing the TBM mission.

    KW - test blanket modules

    KW - error fields

    KW - ITER

    KW - DIII-D

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    U2 - 10.1088/1741-4326/57/3/036004

    DO - 10.1088/1741-4326/57/3/036004

    M3 - Article

    VL - 57

    JO - Nuclear Fusion

    JF - Nuclear Fusion

    SN - 0029-5515

    IS - 3

    M1 - 036004

    ER -

    Lanctot M, Snipes JA, Reimerdes H U, Paz-Soldan C, Logan N, Hanson JM et al. A path to stable low-torque plasma operation in ITER with test blanket modules. Nuclear Fusion. 2017;57(3). 036004. https://doi.org/10.1088/1741-4326/57/3/036004