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An assessment of nitrogen concentrations from spectroscopic measurements in the JET and ASDEX upgrade divertor

JET Contributors; Henderson, S. S.; Bernert, M.; Brezinsek, S.; Carr, M.; Cavedon, M.; Dux, R.; Gahle, D. S.; Harrison, J.; Kallenbach, A.; Lipschultz, B.; Lomanowski, B.; Meigs, A.; O’Mullane, M.; Reimold, F.; Reinke, M. L.; Wiesen, S.; Abduallev, S.; Abhangi, M.; Abreu, P.; Afzal, M.; ... mehr

Abstract:
The impurity concentration in the tokamak divertor plasma is a necessary input for predictive scaling of divertor detachment, however direct measurements from existing tokamaks in different divertor plasma conditions are limited. To address this, we have applied a recently developed spectroscopic N II line ratio technique for measuring the N concentration in the divertor to a range of H-mode and L-mode plasma from the ASDEX Upgrade and JET tokamaks, respectively. The results from both devices show that as the power crossing the separatrix, P$_{sep}$, is increased under otherwise similar core conditions (e.g. density), a higher N concentration is required to achieve the same detachment state. For example, the N concentrations at the start of detachment increase from ≈2% to ≈9% as Psep is increased from ≈2.5 MW to ≈7 MW. These results tentatively agree with scaling law predictions (e.g. Goldston et al.) motivating a further study examining the parameters which affect the N concentration required to reach detachment. Finally, the N concentrations from spectroscopy and the ratio of D and N gas valve fluxes agree within experimental uncertainty only when the vessel surfaces are fully-loaded with N.

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Verlagsausgabe §
DOI: 10.5445/IR/1000119910
Veröffentlicht am 29.05.2020
Originalveröffentlichung
DOI: 10.1016/j.nme.2018.12.012
Scopus
Zitationen: 3
Web of Science
Zitationen: 3
Dimensions
Zitationen: 4
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Angewandte Thermofluidik (IATF)
Institut für Technische Physik (ITEP)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 01.2019
Sprache Englisch
Identifikator ISSN: 2352-1791
KITopen-ID: 1000119910
Erschienen in Nuclear materials and energy
Verlag Elsevier
Band 18
Seiten 147-152
Bemerkung zur Veröffentlichung Kollaboration: EUROfusion MST1 Team ; ASDEX Upgrade Team
Schlagwörter Impurity, Nitrogen, Divertor, Concentration, Spectroscopy, Tokamak
Nachgewiesen in Web of Science
Dimensions
Scopus
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