Advances in radiated power control at DIII-D

D. Eldon, Egemen Kolemen, D. A. Humphreys, A. W. Hyatt, A. E. Järvinen, A. W. Leonard, A. G. McLean, A. L. Moser, T. W. Petrie, M. L. Walker

Research output: Contribution to journalArticle

Abstract

Feedback control of radiated power from the lower divertor P rad, div, L has been implemented in the DIII-D Plasma Control System (PCS). A realtime sensor for P rad, div, L has been constructed from 12 foil bolometer channels which agrees with standard post-shot analysis to within 20%. Results with the 12-channel sensor are compared to initial proof-of-concept tests with a single channel as a proxy for P rad, div, L , showing that the upgraded sensor is necessary to overcome limitations of the proxy channel strategy in DIII-D. Using N 2 seeding under feedback control, P rad, div, L has been increased by up to 150% above unseeded levels, and a radiated power fraction f rad of 80% has been demonstrated, although feedback controlled gas flow is steadier at f rad = 55%. Spatial coverage is broad enough to enable P rad control during the strike point sweeps which are commonly used to generate pseudo-2D divertor Thomson measurements in DIII-D divertor experiments. Use of this control reveals challenges that may affect next step devices, which will require actively controlled extrinsic impurity seeding in order to manage heat loads. When operating at high f rad , changes in pedestal T e (caused by ELMs in these experiments but could come from other disturbances) resulted in large perturbations to P rad which were destabilizing to the feedback controller.

Original languageEnglish (US)
Pages (from-to)285-290
Number of pages6
JournalNuclear Materials and Energy
Volume18
DOIs
StatePublished - Jan 1 2019

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Power control
Feedback control
Sensors
inoculation
feedback control
Feedback
sensors
Bolometers
Thermal load
Metal foil
plasma control
Flow of gases
bolometers
Experiments
Impurities
shot
gas flow
Plasmas
Control systems
foils

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Materials Science (miscellaneous)

Cite this

Eldon, D., Kolemen, E., Humphreys, D. A., Hyatt, A. W., Järvinen, A. E., Leonard, A. W., ... Walker, M. L. (2019). Advances in radiated power control at DIII-D. Nuclear Materials and Energy, 18, 285-290. https://doi.org/10.1016/j.nme.2019.01.010
Eldon, D. ; Kolemen, Egemen ; Humphreys, D. A. ; Hyatt, A. W. ; Järvinen, A. E. ; Leonard, A. W. ; McLean, A. G. ; Moser, A. L. ; Petrie, T. W. ; Walker, M. L. / Advances in radiated power control at DIII-D. In: Nuclear Materials and Energy. 2019 ; Vol. 18. pp. 285-290.
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Eldon, D, Kolemen, E, Humphreys, DA, Hyatt, AW, Järvinen, AE, Leonard, AW, McLean, AG, Moser, AL, Petrie, TW & Walker, ML 2019, 'Advances in radiated power control at DIII-D', Nuclear Materials and Energy, vol. 18, pp. 285-290. https://doi.org/10.1016/j.nme.2019.01.010

Advances in radiated power control at DIII-D. / Eldon, D.; Kolemen, Egemen; Humphreys, D. A.; Hyatt, A. W.; Järvinen, A. E.; Leonard, A. W.; McLean, A. G.; Moser, A. L.; Petrie, T. W.; Walker, M. L.

In: Nuclear Materials and Energy, Vol. 18, 01.01.2019, p. 285-290.

Research output: Contribution to journalArticle

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AU - Eldon, D.

AU - Kolemen, Egemen

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AU - Hyatt, A. W.

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AU - Leonard, A. W.

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Eldon D, Kolemen E, Humphreys DA, Hyatt AW, Järvinen AE, Leonard AW et al. Advances in radiated power control at DIII-D. Nuclear Materials and Energy. 2019 Jan 1;18:285-290. https://doi.org/10.1016/j.nme.2019.01.010