Overview of the results from divertor experiments with attached and detached plasmas at Wendelstein 7-X and their implications for steady-state operation

Jakubowski, M.; Endler, M.; Feng, Y.; Gao, Y.; Killer, C.; König, R.; Krychowiak, M.; Perseo, V.; Reimold, F.; Schmitz, O.; Pedersen, T. S.; Brezinsek, S.; Dinklage, A.; Drewelow, P.; Niemann, H.; Otte, M.; Gruca, M.; Hammond, K.; Kremeyer, T.; Kubkowska, M.; Jabłoński, S.; Pandey, A.; Wurden, G.; Zhang, D.; Bozhenkov, S.; Böckenhoff, D.; Dhard, C. P.; Baldzuhn, J.; Gradic, D.; Effenberg, F.; Kornejew, P.; Lazerson, S.; Lore, J.; Naujoks, D.; Puig Sitjes, A.; Schlisio, G.; Ślęczka, M.; Wenzel, U.; Winters, V.; the W7-X Team,

doi:10.1088/1741-4326/ac1b68

Title: Overview of the results from divertor experiments with attached and detached plasmas at Wendelstein 7-X and their implications for steady-state operation

Journal Article · Mon Aug 30 00:00:00 UTC 2021 · Nuclear Fusion

DOI: https://doi.org/10.1088/1741-4326/ac1b68 · OSTI ID:1835350

;

; Feng, Y.;

;

; Krychowiak, M.;

; Reimold, F.;

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Abstract Wendelstein 7-X (W7-X), the largest advanced stellarator, is built to demonstrate high power, high performance quasi-continuous operation. Therefore, in the recent campaign, experiments were performed to prepare for long pulse operation, addressing three critical issues: the development of stable detachment, control of the heat and particle exhaust, and the impact of leading edges on plasma performance. The heat and particle exhaust in W7-X is realized with the help of an island divertor, which utilizes large magnetic islands at the plasma boundary. This concept shows very efficient heat flux spreading and favourable scaling with input power. Experiments performed to overload leading edges showed that the island divertor yields good impurity screening. A highlight of the recent campaign was a robust detachment scenario, which allowed reducing power loads even by a factor of ten. At the same time, neutral pressures at the pumping gap entrance yielded the particle removal rate close to the values required for stable density control in steady-state operation.

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Research Organization:: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: Polish Ministry of Science and Higher Education; USDOE

Contributing Organization:: EUROfusion Consortium; W7-X Team

Grant/Contract Number:: 89233218CNA000001; AC02-09CH11466; AC05-00OR22725; SC0014210

OSTI ID:: 1835350

Report Number(s):: LA-UR--21-30118

Journal Information:: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 10 Vol. 61; ISSN 0029-5515

Publisher:: IOP PublishingCopyright Statement

Country of Publication:: IAEA

Language:: English

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