Rotation Braking and Error Field Correction of the Test Blanket Module Induced Magnetic Field Error in ITER

H. Reimerdes, J.M. Hanson, Y. In, M. Okabayashi, N. Oyama, J.-K. Park, Antti Salmi, M.J. Schaffer, J.A. Snipes, W.M. Solomon, E.J. Strait, Tuomas Tala

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Abstract

Experiments on DIII-D confirm that the tritium breeding test blanket modules (TBMs) in ITER will lead to a decrease of the plasma rotation in H-modes [M.J. Schaffer, et al., Nucl. Fusion 51 (2011) 103028]. Moreover, they suggest that long-wavelength correction fields applied with non-axisymmetric saddle coils will only be able to ameliorate a fraction of such a rotation reduction. The new finding obtained in rotating H-modes with parameters similar to the ITER baseline scenario contrasts previous experiments, which showed that saddle coils are very effective in restoring resilience to locked modes in L-mode plasmas. The experiments use a TBM mock-up coil that has been especially designed to simulate the error field induced by the ferromagnetic steel of a pair of TBMs in one ITER port. The n = 1 error field correction (EFC) is applied with a set of non-axisymmetric saddle coils (I-coil), whose currents are optimized in the presence of the TBM mock-up field using a newly developed non-disruptive technique that maximizes the angular momentum. However, a test of the effectiveness of the TBM EFC yields that the optimized EFC can only recover approximately a quarter of the ~20% rotation decrease attributed to the TBM error field. An alternative criterion to evaluate EFC has been its effectiveness in canceling the n = 1 plasma response to the field error. Plasma response measurements in the TBM experiment show that the I-coil can indeed cancel the magnetic measurements of the n = 1 plasma response to the TBM mock-up field. The required currents agree within the uncertainties of the estimates with the currents that maximize the angular momentum. The contrast between the limited effectiveness of n = 1 EFC in rotating H-modes and their ability to recover a low locking density in L-mode plasmas shows that the components of the non-axisymmetric field that brake the plasma at higher values of beta or higher rotation differ from the components that are responsible for the field penetration in low density L-modes.
Original languageEnglish
Title of host publicationProgramme, Abstracts, Presentations & Proceedings
Subtitle of host publication24th IAEA Fusion Energy Conference, October 8-13, 2012, San Diego, USA
PublisherInternational Atomic Energy Agency IAEA
Number of pages8
Publication statusPublished - 2012
MoE publication typeA4 Article in a conference publication
Event24th IAEA Fusion Energy Conference - San Diego, United States
Duration: 8 Oct 201213 Oct 2012
http://www-naweb.iaea.org/napc/physics/FEC/FEC2012/html/proceedings.pdf (Full proceedings)

Conference

Conference24th IAEA Fusion Energy Conference
CountryUnited States
CitySan Diego
Period8/10/1213/10/12
Internet address

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braking
blankets
modules
coils
magnetic fields
saddles
angular momentum
resilience
brakes
tritium
locking
magnetic measurement
penetration
fusion
steels

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Reimerdes, H., Hanson, J. M., In, Y., Okabayashi, M., Oyama, N., Park, J-K., ... Tala, T. (2012). Rotation Braking and Error Field Correction of the Test Blanket Module Induced Magnetic Field Error in ITER. In Programme, Abstracts, Presentations & Proceedings: 24th IAEA Fusion Energy Conference, October 8-13, 2012, San Diego, USA [EX/P4-09] International Atomic Energy Agency IAEA.
Reimerdes, H. ; Hanson, J.M. ; In, Y. ; Okabayashi, M. ; Oyama, N. ; Park, J.-K. ; Salmi, Antti ; Schaffer, M.J. ; Snipes, J.A. ; Solomon, W.M. ; Strait, E.J. ; Tala, Tuomas. / Rotation Braking and Error Field Correction of the Test Blanket Module Induced Magnetic Field Error in ITER. Programme, Abstracts, Presentations & Proceedings: 24th IAEA Fusion Energy Conference, October 8-13, 2012, San Diego, USA. International Atomic Energy Agency IAEA, 2012.
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title = "Rotation Braking and Error Field Correction of the Test Blanket Module Induced Magnetic Field Error in ITER",
abstract = "Experiments on DIII-D confirm that the tritium breeding test blanket modules (TBMs) in ITER will lead to a decrease of the plasma rotation in H-modes [M.J. Schaffer, et al., Nucl. Fusion 51 (2011) 103028]. Moreover, they suggest that long-wavelength correction fields applied with non-axisymmetric saddle coils will only be able to ameliorate a fraction of such a rotation reduction. The new finding obtained in rotating H-modes with parameters similar to the ITER baseline scenario contrasts previous experiments, which showed that saddle coils are very effective in restoring resilience to locked modes in L-mode plasmas. The experiments use a TBM mock-up coil that has been especially designed to simulate the error field induced by the ferromagnetic steel of a pair of TBMs in one ITER port. The n = 1 error field correction (EFC) is applied with a set of non-axisymmetric saddle coils (I-coil), whose currents are optimized in the presence of the TBM mock-up field using a newly developed non-disruptive technique that maximizes the angular momentum. However, a test of the effectiveness of the TBM EFC yields that the optimized EFC can only recover approximately a quarter of the ~20{\%} rotation decrease attributed to the TBM error field. An alternative criterion to evaluate EFC has been its effectiveness in canceling the n = 1 plasma response to the field error. Plasma response measurements in the TBM experiment show that the I-coil can indeed cancel the magnetic measurements of the n = 1 plasma response to the TBM mock-up field. The required currents agree within the uncertainties of the estimates with the currents that maximize the angular momentum. The contrast between the limited effectiveness of n = 1 EFC in rotating H-modes and their ability to recover a low locking density in L-mode plasmas shows that the components of the non-axisymmetric field that brake the plasma at higher values of beta or higher rotation differ from the components that are responsible for the field penetration in low density L-modes.",
author = "H. Reimerdes and J.M. Hanson and Y. In and M. Okabayashi and N. Oyama and J.-K. Park and Antti Salmi and M.J. Schaffer and J.A. Snipes and W.M. Solomon and E.J. Strait and Tuomas Tala",
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Reimerdes, H, Hanson, JM, In, Y, Okabayashi, M, Oyama, N, Park, J-K, Salmi, A, Schaffer, MJ, Snipes, JA, Solomon, WM, Strait, EJ & Tala, T 2012, Rotation Braking and Error Field Correction of the Test Blanket Module Induced Magnetic Field Error in ITER. in Programme, Abstracts, Presentations & Proceedings: 24th IAEA Fusion Energy Conference, October 8-13, 2012, San Diego, USA., EX/P4-09, International Atomic Energy Agency IAEA, 24th IAEA Fusion Energy Conference, San Diego, United States, 8/10/12.

Rotation Braking and Error Field Correction of the Test Blanket Module Induced Magnetic Field Error in ITER. / Reimerdes, H.; Hanson, J.M.; In, Y.; Okabayashi, M.; Oyama, N.; Park, J.-K.; Salmi, Antti; Schaffer, M.J.; Snipes, J.A.; Solomon, W.M.; Strait, E.J.; Tala, Tuomas.

Programme, Abstracts, Presentations & Proceedings: 24th IAEA Fusion Energy Conference, October 8-13, 2012, San Diego, USA. International Atomic Energy Agency IAEA, 2012. EX/P4-09.

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

TY - GEN

T1 - Rotation Braking and Error Field Correction of the Test Blanket Module Induced Magnetic Field Error in ITER

AU - Reimerdes, H.

AU - Hanson, J.M.

AU - In, Y.

AU - Okabayashi, M.

AU - Oyama, N.

AU - Park, J.-K.

AU - Salmi, Antti

AU - Schaffer, M.J.

AU - Snipes, J.A.

AU - Solomon, W.M.

AU - Strait, E.J.

AU - Tala, Tuomas

PY - 2012

Y1 - 2012

N2 - Experiments on DIII-D confirm that the tritium breeding test blanket modules (TBMs) in ITER will lead to a decrease of the plasma rotation in H-modes [M.J. Schaffer, et al., Nucl. Fusion 51 (2011) 103028]. Moreover, they suggest that long-wavelength correction fields applied with non-axisymmetric saddle coils will only be able to ameliorate a fraction of such a rotation reduction. The new finding obtained in rotating H-modes with parameters similar to the ITER baseline scenario contrasts previous experiments, which showed that saddle coils are very effective in restoring resilience to locked modes in L-mode plasmas. The experiments use a TBM mock-up coil that has been especially designed to simulate the error field induced by the ferromagnetic steel of a pair of TBMs in one ITER port. The n = 1 error field correction (EFC) is applied with a set of non-axisymmetric saddle coils (I-coil), whose currents are optimized in the presence of the TBM mock-up field using a newly developed non-disruptive technique that maximizes the angular momentum. However, a test of the effectiveness of the TBM EFC yields that the optimized EFC can only recover approximately a quarter of the ~20% rotation decrease attributed to the TBM error field. An alternative criterion to evaluate EFC has been its effectiveness in canceling the n = 1 plasma response to the field error. Plasma response measurements in the TBM experiment show that the I-coil can indeed cancel the magnetic measurements of the n = 1 plasma response to the TBM mock-up field. The required currents agree within the uncertainties of the estimates with the currents that maximize the angular momentum. The contrast between the limited effectiveness of n = 1 EFC in rotating H-modes and their ability to recover a low locking density in L-mode plasmas shows that the components of the non-axisymmetric field that brake the plasma at higher values of beta or higher rotation differ from the components that are responsible for the field penetration in low density L-modes.

AB - Experiments on DIII-D confirm that the tritium breeding test blanket modules (TBMs) in ITER will lead to a decrease of the plasma rotation in H-modes [M.J. Schaffer, et al., Nucl. Fusion 51 (2011) 103028]. Moreover, they suggest that long-wavelength correction fields applied with non-axisymmetric saddle coils will only be able to ameliorate a fraction of such a rotation reduction. The new finding obtained in rotating H-modes with parameters similar to the ITER baseline scenario contrasts previous experiments, which showed that saddle coils are very effective in restoring resilience to locked modes in L-mode plasmas. The experiments use a TBM mock-up coil that has been especially designed to simulate the error field induced by the ferromagnetic steel of a pair of TBMs in one ITER port. The n = 1 error field correction (EFC) is applied with a set of non-axisymmetric saddle coils (I-coil), whose currents are optimized in the presence of the TBM mock-up field using a newly developed non-disruptive technique that maximizes the angular momentum. However, a test of the effectiveness of the TBM EFC yields that the optimized EFC can only recover approximately a quarter of the ~20% rotation decrease attributed to the TBM error field. An alternative criterion to evaluate EFC has been its effectiveness in canceling the n = 1 plasma response to the field error. Plasma response measurements in the TBM experiment show that the I-coil can indeed cancel the magnetic measurements of the n = 1 plasma response to the TBM mock-up field. The required currents agree within the uncertainties of the estimates with the currents that maximize the angular momentum. The contrast between the limited effectiveness of n = 1 EFC in rotating H-modes and their ability to recover a low locking density in L-mode plasmas shows that the components of the non-axisymmetric field that brake the plasma at higher values of beta or higher rotation differ from the components that are responsible for the field penetration in low density L-modes.

M3 - Conference article in proceedings

BT - Programme, Abstracts, Presentations & Proceedings

PB - International Atomic Energy Agency IAEA

ER -

Reimerdes H, Hanson JM, In Y, Okabayashi M, Oyama N, Park J-K et al. Rotation Braking and Error Field Correction of the Test Blanket Module Induced Magnetic Field Error in ITER. In Programme, Abstracts, Presentations & Proceedings: 24th IAEA Fusion Energy Conference, October 8-13, 2012, San Diego, USA. International Atomic Energy Agency IAEA. 2012. EX/P4-09