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DOE OSTI · 3002146

Double-null power-sharing dynamics in MAST-U

Kool, Bob [Dutch Institute for Fundamental Energy Research (DIFFER), Eindhoven (Netherlands); Eindhoven Univ. of Technology (Netherlands)] (ORCID:0000000216367400)·van den Doel, Thomas M. [Dutch Institute for Fundamental Energy Research (DIFFER), Eindhoven (Netherlands); Eindhoven Univ. of Technology (Netherlands)]·Derks, Gijs L. [Dutch Institute for Fundamental Energy Research (DIFFER), Eindhoven (Netherlands); Eindhoven Univ. of Technology (Netherlands)] (ORCID:0000000334200388)·Henderson, Stuart S. [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)] (ORCID:0000000288861256)·Lovell, Jack [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000195653466)·Bardsley, Oliver P. [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)] (ORCID:000000021525675X)·Lafferty, Mark [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)]·Wijkamp, Tijs A. [Dutch Institute for Fundamental Energy Research (DIFFER), Eindhoven (Netherlands)] (ORCID:0000000331108682)·Figueiredo, Paulo A. [Dutch Institute for Fundamental Energy Research (DIFFER), Eindhoven (Netherlands)] (ORCID:0009000470526793)·Silburn, Scott [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)] (ORCID:0000000231115113)·Tookey, Alex [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)]·Scannell, Rory [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)]·Lonigro, N. [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom); Univ. of York (United Kingdom)] (ORCID:0000000185810384)·Stobbs, Jessica M. [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)]·Kogan, Lucy [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)]·Verhaegh, Kevin [Eindhoven Univ. of Technology (Netherlands); United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)] (ORCID:0000000205002764)·van Berkel, Matthijs [Dutch Institute for Fundamental Energy Research (DIFFER), Eindhoven (Netherlands); Eindhoven Univ. of Technology (Netherlands)] (ORCID:0000000165743823)
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Abstract

Maintaining an effective double-null (DN) configuration is expected to be challenging in reactor-scale tokamak devices. As divertor power-sharing is closely linked to the magnetic topology, even minor variations can lead to fast power-sharing fluctuations which exacerbate the already daunting exhaust challenge. While the static aspects of DN power-sharing have been extensively studied across various devices, this paper presents the first detailed investigation of its dynamic behaviour. We employ dedicated H-mode experiments in MAST-U, in Super-X divertor configuration, featuring perturbation frequencies up to 200 Hz. Our results clearly show no significant dynamic damping of the power-sharing within this frequency range: the divertor responds equally to both fast and slow perturbations. Moreover, the dynamic response also aligns with quasi-static results from slow ramps, implying that static power-sharing models remain valid even for fast fluctuations. Occasionally, some deviations from the otherwise mainly linear behaviour are observed, alongside notable scatter and asymmetries between upwards and downwards trajectories. These observations are likely linked to changes in core conditions, though the underlying mechanisms remain unclear and require further study.

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divertordynamic double-nullpower-sharingsystem identificationtokamak exhaust

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Kool, Bob [Dutch Institute for Fundamental Energy Research (DIFFER), Eindhoven (Netherlands); Eindhoven Univ. of Technology (Netherlands)] (ORCID:0000000216367400), van den Doel, Thomas M. [Dutch Institute for Fundamental Energy Research (DIFFER), Eindhoven (Netherlands); Eindhoven Univ. of Technology (Netherlands)], Derks, Gijs L. [Dutch Institute for Fundamental Energy Research (DIFFER), Eindhoven (Netherlands); Eindhoven Univ. of Technology (Netherlands)] (ORCID:0000000334200388), Henderson, Stuart S. [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)] (ORCID:0000000288861256), Lovell, Jack [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000195653466), Bardsley, Oliver P. [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)] (ORCID:000000021525675X), Lafferty, Mark [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)], Wijkamp, Tijs A. [Dutch Institute for Fundamental Energy Research (DIFFER), Eindhoven (Netherlands)] (ORCID:0000000331108682), Figueiredo, Paulo A. [Dutch Institute for Fundamental Energy Research (DIFFER), Eindhoven (Netherlands)] (ORCID:0009000470526793), Silburn, Scott [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)] (ORCID:0000000231115113), Tookey, Alex [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)], Scannell, Rory [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)], Lonigro, N. [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom); Univ. of York (United Kingdom)] (ORCID:0000000185810384), Stobbs, Jessica M. [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)], Kogan, Lucy [United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)], Verhaegh, Kevin [Eindhoven Univ. of Technology (Netherlands); United Kingdom Atomic Energy Authority (UKAEA), Abingdon (United Kingdom)] (ORCID:0000000205002764), van Berkel, Matthijs [Dutch Institute for Fundamental Energy Research (DIFFER), Eindhoven (Netherlands); Eindhoven Univ. of Technology (Netherlands)] (ORCID:0000000165743823). 2025-09-24. Double-null power-sharing dynamics in MAST-U. https://doi.org/10.1088/1741-4326%2Fae04fe

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