On the applicability of three and four parameter fits for analysis of swept embedded Langmuir probes in magnetised plasma

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21340%2F22%3A00366386" target="_blank" >RIV/68407700:21340/22:00366386 - isvavai.cz</a>

Alternative codes found

RIV/61389021:_____/22:00565842

Result on the web

<a href="https://doi.org/10.1088/1741-4326/ac8011" target="_blank" >https://doi.org/10.1088/1741-4326/ac8011</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1088/1741-4326/ac8011" target="_blank" >10.1088/1741-4326/ac8011</a>

Result language

angličtina

Original language name

On the applicability of three and four parameter fits for analysis of swept embedded Langmuir probes in magnetised plasma

Original language description

The problem of power exhaust is one of the grand challenges of nuclear fusion research today. In order to understand the physics phenomena occurring in the scrape-off layer and the divertor regions of tokamaks, it is essential to correctly determine the divertor plasma parameters, which are often measured by swept Langmuir probes. While the construction and operation of this diagnostic can be straightforward, the data analysis using 3- or 4-parameter fits presents a challenge and can potentially lead to erroneous values of electron temperature and ion saturation current. In this work, we present modelling and experiments aimed at determination of conditions for proper analysis of swept Langmuir probes using these two fitting models. Particle-in- cell modelling was employed to evaluate the sheath-expansion effects for particular probe geometry and plasma conditions, yielding a semi-empirical rule capable of predicting its magnitude. Experiments with unusually wide range of swept voltage in the divertor of the COMPASS tokamak explored the magnitude of voltage range required for successful analysis with either three or four-parameter fitting. With the use of our new semi-empirical rule, it is possible to improve the four-parameter fit reliability in situations where the available voltage range is limited. In addition, we introduce the tangent method - an independent and fast method of electron temperature estimation, which allows to reliably determine the available voltage range and as such assist the more complex method of probe analysis.

Czech name

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Czech description

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Type

J_imp - 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)

Project

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Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2022

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Nuclear Fusion

ISSN

0029-5515

e-ISSN

1741-4326

Volume of the periodical

62

Issue of the periodical within the volume

Sep

Country of publishing house

AT - AUSTRIA

Number of pages

17

Pages from-to

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UT code for WoS article

000837837000001

EID of the result in the Scopus database

2-s2.0-85136141456