Divertor detachment and reattachment with mixed impurity seeding on ASDEX Upgrade

S. S. Henderson; M. Bernert; D. Brida; M. Cavedon; P. David; R. Dux; O. Février; Aaro Järvinen; A. Kallenbach; M. Komm; R. McDermott; M. O’Mullane; EUROfusion MST1 Team; ASDEX Upgrade Team

doi:10.1088/1741-4326/ace2d6

Divertor detachment and reattachment with mixed impurity seeding on ASDEX Upgrade

S. S. Henderson (Corresponding Author), M. Bernert, D. Brida, M. Cavedon, P. David, R. Dux, O. Février, Aaro Järvinen, A. Kallenbach, M. Komm, R. McDermott, M. O’Mullane, EUROfusion MST1 Team, ASDEX Upgrade Team

Research output: Contribution to journal › Article › Scientific › peer-review

17 Citations (Scopus)

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.

Original language	English
Article number	086024
Number of pages	13
Journal	Nuclear Fusion
Volume	63
Issue number	8
DOIs	https://doi.org/10.1088/1741-4326/ace2d6
Publication status	Published - Aug 2023
MoE publication type	A1 Journal article-refereed

Keywords

divertor detachment
divertor reattachment
impurity seeding

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1088/1741-4326/ace2d6Licence: CC BY

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Henderson, S. S., Bernert, M., Brida, D., Cavedon, M., David, P., Dux, R., Février, O., Järvinen, A., Kallenbach, A., Komm, M., McDermott, R., O’Mullane, M., EUROfusion MST1 Team, & ASDEX Upgrade Team (2023). Divertor detachment and reattachment with mixed impurity seeding on ASDEX Upgrade. Nuclear Fusion, 63(8), Article 086024. 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.",

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author = "Henderson, {S. S.} and M. Bernert and D. Brida and M. Cavedon and P. David and R. Dux and O. F{\'e}vrier and Aaro J{\"a}rvinen and A. Kallenbach and M. Komm and R. McDermott and M. O{\textquoteright}Mullane and {EUROfusion MST1 Team} and {ASDEX Upgrade Team}",

note = "Funding Information: This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No. 101052200 - EUROfusion) and from the EPSRC (Grant Number EP/W006839/1). The Swiss contribution to this work has been funded by the Swiss State Secretariat for Education, Research and Innovation (SERI). To obtain further information on the data and models underlying this paper please contact [email protected]. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union, the European Commission, or SERI. Neither the European Union nor the European commission nor SERI can be held responsible for them. Publisher Copyright: {\textcopyright} 2023 Crown copyright, UKAEA",

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AU - David, P.

AU - Dux, R.

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AU - Järvinen, Aaro

AU - Kallenbach, A.

AU - Komm, M.

AU - McDermott, R.

AU - O’Mullane, M.

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N1 - Funding Information: This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No. 101052200 - EUROfusion) and from the EPSRC (Grant Number EP/W006839/1). The Swiss contribution to this work has been funded by the Swiss State Secretariat for Education, Research and Innovation (SERI). To obtain further information on the data and models underlying this paper please contact [email protected]. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union, the European Commission, or SERI. Neither the European Union nor the European commission nor SERI can be held responsible for them. Publisher Copyright: © 2023 Crown copyright, UKAEA

PY - 2023/8

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N2 - 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.

AB - 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.

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JO - Nuclear Fusion

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Divertor detachment and reattachment with mixed impurity seeding on ASDEX Upgrade

Abstract

Keywords

UN SDGs

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ECO-Fusion: Finnish Ecosystem for Industrial Fusion Technology

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Divertor detachment and reattachment with mixed impurity seeding on ASDEX Upgrade

Abstract

Keywords

UN SDGs

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Projects

ECO-Fusion: Finnish Ecosystem for Industrial Fusion Technology

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