Divertor detachment and reattachment with mixed impurity seeding on ASDEX Upgrade
Henderson, S.S. and Bernert, M. and Brida, D. and Cavedon, M. and David, P. and Dux, R. and Février, O. and Järvinen, A. and Kallenbach, A. and Komm, M. and McDermott, R. and O’Mullane, M., The ASDEX Upgrade Team, The EUROfusion MST1 team (2023) Divertor detachment and reattachment with mixed impurity seeding on ASDEX Upgrade. Nuclear Fusion, 63 (8). 086024. ISSN 0029-5515 (https://doi.org/10.1088/1741-4326/ace2d6)
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Abstract
Using newly developed spectroscopic models to measure the divertor concentration of Ne and Ar, it is shown that the experimental detachment threshold on ASDEX Upgrade with Ar-only and mixtures of Ar+N or Ne+N scales as expected in comparison with an analytical equation derived by Kallenbach et al (2016 Plasma Phys. Control. Fusion 58 045013). However, it is found that Ar radiates more efficiently and Ne less efficiently in the scrape-off layer than the model predicts. By separately increasing the neutral beam injection power and cutting the impurity gas flow, it is shown that the partially detached and strongly detached X-point radiator scenarios reattach in ≈100 ms and ≈250 ms, respectively. The former timescale is set by the core energy confinement time, whereas the latter has an additional delay caused by the time required for the ionisation front to move from the X-point to the target. A simple equation with scalable geometric terms to predict the ionisation front movement time in future machines is proposed.
ORCID iDs
Henderson, S.S., Bernert, M., Brida, D., Cavedon, M., David, P., Dux, R., Février, O., Järvinen, A., Kallenbach, A., Komm, M., McDermott, R. and O’Mullane, M. ORCID: https://orcid.org/0000-0002-2160-4546;-
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Item type: Article ID code: 86098 Dates: DateEvent1 August 2023Published7 July 2023Published Online29 June 2023Accepted6 March 2023SubmittedSubjects: Science > Physics > Nuclear and particle physics. Atomic energy. Radioactivity Department: Faculty of Science > Physics Depositing user: Pure Administrator Date deposited: 11 Jul 2023 08:28 Last modified: 14 Sep 2024 22:52 URI: https://strathprints.strath.ac.uk/id/eprint/86098