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. Solomon & 2 others T. 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.
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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

UR - http://www.scopus.com/inward/record.url?scp=85013371951&partnerID=8YFLogxK

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