Kool, B.

Wijkamp, T.A.

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 First MAST-U detachment results indicate enhanced role ofmoleculesCitation for published version (APA):MAST Upgrade team, Kool, B., & Wijkamp, T. A. (2022). First MAST-U detachment results indicate enhancedrole of molecules. In 48th EPS Conference on Plasma Physics 27 June - 1 July 2022 (Europhysics conferenceabstracts; Vol. 46A). European Physical Society (EPS). http://ocs.ciemat.es/EPS2022PAP/pdf/O3.107.pdfDocument status and date:Published: 01/01/2022Document Version:Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can beimportant differences between the submitted version and the official published version of record. Peopleinterested in the research are advised to contact the author for the final version of the publication, or visit theDOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and pagenumbers.Link to publicationGeneral rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            • Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            • You may not further distribute the material or use it for any profit-making activity or commercial gain            • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, pleasefollow below link for the End User Agreement:www.tue.nl/taverneTake down policyIf you believe that this document breaches copyright please contact us at:openaccess@tue.nlproviding details and we will investigate your claim.Download date: 05. Oct. 2023First MAST-U detachment results indicate enhanced role of molecules K. Verhaegh1*, B. Lipschultz2, J.R. Harrison1, J. Allcock1, B. Kool3,4, N. Osborne5,1, P. Ryan1, T.A. Wijkamp3,4, A. Williams2,1, J.G. Clark5,1, F. Federici2, D. Moulton1, A. Thornton1, L. Xiang1 and the MAST-U team* 1 United Kingdom Atomic Energy Agency, Culham Centre for Fusion Energy, Abingdon, United Kingdom 2 University of York, York, United Kingdom 3 Eindhoven University of Technology, Eindhoven, The Netherlands 4Dutch Institute for Fundamental Energy Research (DIFFER), Eindhoven, The Netherlands 5University of Liverpool, Liverpool, United Kingdom  *See author list of J. Harrison, et al. 2019 Nucl. Fusion   MAST-U is a new spherical tokamak with a tightly baffled, double null Super-X divertor. This configuration increases the operational window of detachment, which is a necessity for power exhaust on reactors. The physics of detachment is analysed during a core density ramp using novel Balmer line spectroscopic analysis that shows four phases of detachment. In Phase I the ionisation region detaches from the target and the plasma interacts with the cloud of molecules below it, leading to molecular ions with low target electron temperature (Te,t < 5 eV). Those ions react with the plasma leading to ion losses and neutral sources through Molecular Activated Recombination and Dissociation (MAR and MAD). Further increases in the core plasma density results in the divertor plasma having insufficient energy to promote the creation of molecular ions (Te,t < 1 eV), leading to a separation of the MAR region from the target (phase II). If the core density is further increased, electron-ion recombination (EIR) starts to appear (with Te,t ≤ 0.2 eV diagnosed) (phase III); ultimately, the EIR region detaches from the target as the electron density decays near the target (phase IV, not shown).  Our results, which will be compared against simulations, show plasma-molecule interactions are critically important beyond the detachment onset and are a key element of the Super-X divertor as the ionisation can be held stably from the target with a molecular interaction region below it. 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/T012250/1] 48th EPS Conference on Plasma Physics O3.107

First MAST-U detachment results indicate enhanced role of molecules

https://pure.tue.nl/ws/files/274268633/O3.107.pdf

First MAST-U detachment results indicate enhanced role of molecules

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