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Impact of impurity seeding on the electron energy distribution function in the COMPASS divertor region

SYSNO ASEP	0539282
Document Type	J - Journal Article
R&D Document Type	Journal Article
Subsidiary J	Článek ve WOS
Title	Impact of impurity seeding on the electron energy distribution function in the COMPASS divertor region
Author(s)	Dimitrova, Miglena (UFP-V)_ORCID Popov, Tsv.K. (BG) Kovacic, J. (SI) Dejarnac, Renaud (UFP-V)_{RID, ORCID} Gunn, J. P. (FR) Ivanova, P. (BG) Imríšek, Martin (UFP-V)_RID Stöckel, Jan (UFP-V)_RID Vondráček, Petr (UFP-V)_{RID, ORCID} Hron, Martin (UFP-V)_{RID, ORCID} Pánek, Radomír (UFP-V)_RID
Number of authors	11
Article number	125015
Source Title	Plasma Physics and Controlled Fusion. - : Institute of Physics Publishing - ISSN 0741-3335 Roč. 62, č. 12 (2020)
Number of pages	13 s.
Language	eng - English
Country	GB - United Kingdom
Keywords	Divertor Langmuir probes ; Electron energy distribution function ; Impurity seeding ; Parallel heat-flux densities ; Tokamak COMPASS
Subject RIV	BL - Plasma and Gas Discharge Physics
OECD category	Fluids and plasma physics (including surface physics)
R&D Projects	GA20-28161S GA ČR - Czech Science Foundation (CSF)
	LM2018117 GA MŠMT - Ministry of Education, Youth and Sports (MEYS)
	8D15001 GA MŠMT - Ministry of Education, Youth and Sports (MEYS)
	EF16_019/0000768 GA MŠMT - Ministry of Education, Youth and Sports (MEYS)
Method of publishing	Limited access
Institutional support	UFP-V - RVO:61389021
UT WOS	000585706800001
EID SCOPUS	85095817913
DOI	10.1088/1361-6587/abc08f
Annotation	In the COMPASS tokamak, series of experiments were performed aimed at studying the impact of nitrogen, neon, and argon impurity seeding on the electron energy distribution function (EEDF) in the divertor region. The experiments were conducted in D-shaped, L-mode, deuterium plasmas. In order to obtain the radial distribution of the floating potential, ion saturation current, electron temperatures, and densities, the current-voltage characteristics were measured by Langmuir probes embedded in the COMPASS tokamak divertor. The properties of the plasma in the divertor region were measured before and during impurity seeding. Before the N2 seeding, the EEDF was bi-Maxwellian with a low-energy electron fraction with temperatures 3.5–5 eV, and a higher-energy one with temperatures in the range of 10 eV to 23 eV. During seeding with an increasing number of molecules per second, the EEDF changed from bi-Maxwellian to Maxwellian and the electron temperature decreased. The time-evolution was studied of the change in the EEDF during N2 seeding. When the seeding was carried out by a valve in the private flux region, the duration of the transition from a bi-Maxwellian to a Maxwellian EEDF was about 10–15 ms. When the N2 seeding took place through a low-field side valve, the transition from a bi-Maxwellian to a Maxwellian EEDF took longer −25–45 ms. The temporal evolution was also analyzed of the plasma parameters’ radial profiles when neon and argon were puffed using a valve in the divertor low-field side. The application is discussed of the probe measurements’ results to calculating the parallel heat-flux densities in the divertor region of the COMPASS tokamak.
Workplace	Institute of Plasma Physics
Contact	Vladimíra Kebza, kebza@ipp.cas.cz, Tel.: 266 052 975
Year of Publishing	2021
Electronic address	https://iopscience.iop.org/article/10.1088/1361-6587/abc08f

Number of the records: 1