Interpretation of flush-mounted probe current-voltage characteristics using four-parametric fits

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389021%3A_____%2F19%3A00509576" target="_blank" >RIV/61389021:_____/19:00509576 - isvavai.cz</a>

Alternative codes found

RIV/00216208:11320/19:10406964

Result on the web

<a href="https://iopscience.iop.org/article/10.1088/1361-6587/ab3de8" target="_blank" >https://iopscience.iop.org/article/10.1088/1361-6587/ab3de8</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1088/1361-6587/ab3de8" target="_blank" >10.1088/1361-6587/ab3de8</a>

Result language

angličtina

Original language name

Interpretation of flush-mounted probe current-voltage characteristics using four-parametric fits

Original language description

The evaluation of probe measurements in the swept regime can be performed via a fit to the ion branch of the current-voltage (I-V) characteristic, providing the most relevant plasma parameters such as the ion saturation current, the electron temperature and the floating potential. In this paper, we present a parametric study based upon the existing flush-mounted probe setup briefly operated at the COMPASS tokamak, aiming to compare relevant I-V formulas widely used for such analysis. Selected four-parametric fit descriptions were applied to synthetic data obtained by simulation of the probe in a particle-in-cell model, SPICE, both in simplified 2D and more complex 3D geometries. Plasma parameters recovered by the fit were compared to the input from the model and the precision of this recovery was mapped to a wide range of parameters, especially with respect to the ratio of the probe size d pin to the Larmor radius r L. Results show that while the electron temperature and the floating potential can be obtained quite precisely regardless of the method, the ion saturation current can be identified incorrectly, mainly due to the fact that the sheath expansion description by optical approximation is not sufficient for almost grazing field line angles of incidence, especially when d pin ∼ r L. We show, however, that operation of flush-mounted probes can be fruitful especially in high-field devices. Additionally, we have explored the sensitivity on the available bias potential range, showing that for proper analysis of I-V characteristic using four-parametric fit, the lower bound of the fit range should be at least below the floating potential. If this condition cannot be satisfied, three-parametric fit in the range close to the floating potential can still produce results with acceptable precision.

Czech name

—

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

—

OECD FORD branch

10305 - Fluids and plasma physics (including surface physics)

Project

<a href="/en/project/LM2015045" target="_blank" >LM2015045: COMPASS – Tokamak for Thermonuclear Fusion Research</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2019

Confidentiality

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

Name of the periodical

Plasma Physics and Controlled Fusion

ISSN

0741-3335

e-ISSN

—

Volume of the periodical

61

Issue of the periodical within the volume

10

Country of publishing house

GB - UNITED KINGDOM

Number of pages

16

Pages from-to

105011

UT code for WoS article

000485695000001

EID of the result in the Scopus database

2-s2.0-85072713243