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High-n Rydberg transition spectroscopy for heavy impurity transport studies in W7-X (invited)

W7-X Team 1; Swee, Colin ; Geiger, Benedikt; Ford, Oliver; O’Mullane, Martin; Poloskei, Peter; Reimold, Felix; Romba, Thilo; Wegner, Thomas
1 Institut für Hochleistungsimpuls- und Mikrowellentechnik (IHM), Karlsruher Institut für Technologie (KIT)

Abstract (englisch):

Here, we present a novel spectroscopy approach to investigate impurity transport by analyzing line-radiation following high-n Rydberg transitions. While high-n Rydberg states of impurity ions are unlikely to be populated via impact excitation, they can be accessed by charge exchange (CX) reactions along the neutral beams in high-temperature plasmas. Hence, localized radiation of highly ionized impurities, free of passive contributions, can be observed at multiple wavelengths in the visible range. For the analysis and modeling of the observed Rydberg transitions, a technique for calculating effective emission coefficients is presented that can well reproduce the energy dependence seen in datasets available on the OPEN-ADAS database. By using the rate coefficients and comparing modeling results with the new high-n Rydberg CX measurements, impurity transport coefficients are determined with well-documented 2σ confidence intervals for the first time. This demonstrates that high-n Rydberg spectroscopy provides important constraints on the determination of impurity transport coefficients. By additionally considering Bolometer measurements, which provide constraints on the overall impurity emissivity and, therefore, impurity densities, error bars can be reduced even further.


Zugehörige Institution(en) am KIT Institut für Hochleistungsimpuls- und Mikrowellentechnik (IHM)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 09.2024
Sprache Englisch
Identifikator ISSN: 0034-6748, 1089-7623
KITopen-ID: 1000175575
HGF-Programm 31.13.02 (POF IV, LK 01) Plasma Heating & Current Drive Systems
Erschienen in Review of Scientific Instruments
Verlag American Institute of Physics (AIP)
Band 95
Heft 9
Seiten Art.-Nr.: 093539
Projektinformation EUROfusion (EU, EU 9. RP, 101052200)
Nachgewiesen in Web of Science
Scopus
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