Experimental characterization of the active and passive fast-ion H-alpha emission in W7-X using FIDASIM

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2024-02
Major/Subject
Mcode
Degree programme
Language
en
Pages
Series
Nuclear Fusion, Volume 64, issue 2
Abstract
This paper presents the first results from the analysis of Balmer-alpha spectra at Wendelstein 7-X which contain the broad charge exchange emission from fast-ions. The measured spectra are compared to synthetic spectra predicted by the FIDASIM code, which has been supplied with the 3D magnetic fields from VMEC, 5D fast-ion distribution functions from ASCOT, and a realistic Neutral Beam Injection geometry including beam particle blocking elements. Detailed modeling of the beam emission shows excellent agreement between measured beam emission spectra and predictions. In contrast, modeling of beam halo radiation and Fast-Ion H-Alpha signals (FIDA) is more challenging due to strong passive contributions. While about 50% of the halo radiation can be attributed to passive signals from edge neutrals, the FIDA emission—in particular for an edge-localized line of sights—is dominated by passive emission. This is in part explained by high neutral densities in the plasma edge and in part by edge-born fast-ion populationsas demonstrated by detailed modeling of the edge fast-ion distribution.
Description
Funding Information: This work has been carried out within the framework of the EUROfusion consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 under Grant Agreement Number 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. | openaire: EC/H2020/633053/EU//EUROfusion
Keywords
fast-particle diagnostic, forward modelling, plasma physics, stellarator
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Citation
Poloskei , P Z , Geiger , B , Jansen van Vuuren , A , Äkäslompolo , S , Ford , O , Spanier , A , Neelis , T W C , McNeely , P , Hartmann , D & W7X-Team 2024 , ' Experimental characterization of the active and passive fast-ion H-alpha emission in W7-X using FIDASIM ' , Nuclear Fusion , vol. 64 , no. 2 , 026008 . https://doi.org/10.1088/1741-4326/ad0dd4