Study of ion-to-electron temperature ratio at the edge of Wendelstein 7-X using a fast swept ball-pen probe
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389021%3A_____%2F25%3A00647282" target="_blank" >RIV/61389021:_____/25:00647282 - isvavai.cz</a>
Result on the web
<a href="https://iopscience.iop.org/article/10.1088/1361-6587/ae1b6b" target="_blank" >https://iopscience.iop.org/article/10.1088/1361-6587/ae1b6b</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1088/1361-6587/ae1b6b" target="_blank" >10.1088/1361-6587/ae1b6b</a>
Alternative languages
Result language
angličtina
Original language name
Study of ion-to-electron temperature ratio at the edge of Wendelstein 7-X using a fast swept ball-pen probe
Original language description
In the Wendelstein 7-X (W7-X) stellarator, a ball-pen probe (BPP) has been routinely employed to measure Ti in the island scrape-off layer (SOL) across large parts of the recent 2024/2025 campaigns. The high temporal resolution of 25 mu s allows us to resolve Ti fluctuations, their probability density functions, and modulation via low-frequency magnetohydrodynamics (MHD) modes. We present a unique comparison of the ion temperature measured using BPP with a more conventional retarding field analyzer (RFA). A good agreement between the two diagnostics is observed, when fast Ti measurements are reduced to the same temporal resolution (5 ms) using 'RFA-like' averaging. Using an RFA-like interpretation of the fast BPP data, we find a linear decrease in SOL Ti and Te with line-integrated density. The SOL ion-to-electron temperature ratio tau i,e ranges between tau i,e= 1 and 3 with smaller tau i,e values observed for higher densities (collisionalities) and at positions close to the LCFS. The upstream BPP Ti measurements are compared to the average C2+ Ti obtained by coherence imaging spectroscopy (CIS), in the divertor region, magnetically mapped to the BPP. The downstream Ti measured by CIS is about half the upstream Ti and exhibits a similar inverse scaling with line-integrated density. Finally, we benchmark the experimentally obtained SOL Ti and Te against the EMC3-Eirene modeling and find good agreement for high density plasmas, but significantly diverging results for low density plasmas.
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10305 - Fluids and plasma physics (including surface physics)
Result continuities
Project
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Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2025
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Plasma Physics and Controlled Fusion
ISSN
0741-3335
e-ISSN
1361-6587
Volume of the periodical
67
Issue of the periodical within the volume
11
Country of publishing house
US - UNITED STATES
Number of pages
14
Pages from-to
115029
UT code for WoS article
001620224700001
EID of the result in the Scopus database
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