Interaction of candidate plasma facing materials with tokamak plasma in COMPASS

Jiří Matějíček, Vladimír Weinzettl, Anna Macková, Petr Malinský, Vladimír Havránek, Diana Naydenkova, Veronika Klevarová, Per Petersson, Pawel Gasior, Antti Hakola, Marek Rubel, Elzbieta Fortuna, Jukka Kolehmainen, Sanna Tervakangas

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)

Abstract

The interaction of tokamak plasma with several materials considered for the plasma facing components of future fusion devices was studied in a small-size COMPASS tokamak. These included mainly tungsten as the prime candidate and chromium steel as an alternative whose suitability was to be assessed. For the experiments, thin coatings of tungsten, P92 steel and nickel on graphite substrates were prepared by arc-discharge sputtering. The samples were exposed to hydrogen and deuterium plasma discharges in the COMPASS tokamak in two modes: a) short exposure (several discharges) on a manipulator in the proximity of the separatrix, close to the central column, and b) long exposure (several months) at the central column, aligned with the other graphite tiles. During the discharges, standard plasma diagnostics were used and a local emission of spectral lines in the visible near ultraviolet regions, corresponding to the material erosion, was monitored. Before and after the plasma exposures, the sample surfaces were observed using scanning electron microscopy, the coatings thickness was measured using Rutherford backscattering spectroscopy, and the concentration profiles of hydrogen and deuterium were measured by elastic recoil detection analysis. The uniformity of the coatings and their thickness was verified before the exposure. After the exposure, no reduction of the thickness was observed, indicating the absence of ‘global’ erosion. Erosion was observed only in isolated spots, and attributed to unipolar arcing. Slightly larger erosion was found on the steel coatings compared to the tungsten ones. Incorporation of deuterium in a thin surface layer was observed, in dependence on the exposure mode. Additionally, boron enrichment of the long-exposure samples was observed, as a result of the tokamak chamber boronization.

Original languageEnglish
Pages (from-to)102-119
Number of pages18
JournalJournal of Nuclear Materials
Volume493
DOIs
Publication statusPublished - 1 Sep 2017
MoE publication typeA1 Journal article-refereed

Fingerprint

COMPASS (programming language)
Beam plasma interactions
Tungsten
Deuterium
Erosion
Steel
Plasmas
Coatings
Graphite
erosion
Hydrogen
coatings
interactions
tungsten
Plasma diagnostics
steels
Boron
Rutherford backscattering spectroscopy
Chromium
Tile

Cite this

Matějíček, J., Weinzettl, V., Macková, A., Malinský, P., Havránek, V., Naydenkova, D., ... Tervakangas, S. (2017). Interaction of candidate plasma facing materials with tokamak plasma in COMPASS. Journal of Nuclear Materials, 493, 102-119. https://doi.org/10.1016/j.jnucmat.2017.06.009
Matějíček, Jiří ; Weinzettl, Vladimír ; Macková, Anna ; Malinský, Petr ; Havránek, Vladimír ; Naydenkova, Diana ; Klevarová, Veronika ; Petersson, Per ; Gasior, Pawel ; Hakola, Antti ; Rubel, Marek ; Fortuna, Elzbieta ; Kolehmainen, Jukka ; Tervakangas, Sanna. / Interaction of candidate plasma facing materials with tokamak plasma in COMPASS. In: Journal of Nuclear Materials. 2017 ; Vol. 493. pp. 102-119.
@article{656da8ac7b434bcba087d7f18389ec26,
title = "Interaction of candidate plasma facing materials with tokamak plasma in COMPASS",
abstract = "The interaction of tokamak plasma with several materials considered for the plasma facing components of future fusion devices was studied in a small-size COMPASS tokamak. These included mainly tungsten as the prime candidate and chromium steel as an alternative whose suitability was to be assessed. For the experiments, thin coatings of tungsten, P92 steel and nickel on graphite substrates were prepared by arc-discharge sputtering. The samples were exposed to hydrogen and deuterium plasma discharges in the COMPASS tokamak in two modes: a) short exposure (several discharges) on a manipulator in the proximity of the separatrix, close to the central column, and b) long exposure (several months) at the central column, aligned with the other graphite tiles. During the discharges, standard plasma diagnostics were used and a local emission of spectral lines in the visible near ultraviolet regions, corresponding to the material erosion, was monitored. Before and after the plasma exposures, the sample surfaces were observed using scanning electron microscopy, the coatings thickness was measured using Rutherford backscattering spectroscopy, and the concentration profiles of hydrogen and deuterium were measured by elastic recoil detection analysis. The uniformity of the coatings and their thickness was verified before the exposure. After the exposure, no reduction of the thickness was observed, indicating the absence of ‘global’ erosion. Erosion was observed only in isolated spots, and attributed to unipolar arcing. Slightly larger erosion was found on the steel coatings compared to the tungsten ones. Incorporation of deuterium in a thin surface layer was observed, in dependence on the exposure mode. Additionally, boron enrichment of the long-exposure samples was observed, as a result of the tokamak chamber boronization.",
author = "Jiř{\'i} Matěj{\'i}ček and Vladim{\'i}r Weinzettl and Anna Mackov{\'a} and Petr Malinsk{\'y} and Vladim{\'i}r Havr{\'a}nek and Diana Naydenkova and Veronika Klevarov{\'a} and Per Petersson and Pawel Gasior and Antti Hakola and Marek Rubel and Elzbieta Fortuna and Jukka Kolehmainen and Sanna Tervakangas",
year = "2017",
month = "9",
day = "1",
doi = "10.1016/j.jnucmat.2017.06.009",
language = "English",
volume = "493",
pages = "102--119",
journal = "Journal of Nuclear Materials",
issn = "0022-3115",
publisher = "Elsevier",

}

Matějíček, J, Weinzettl, V, Macková, A, Malinský, P, Havránek, V, Naydenkova, D, Klevarová, V, Petersson, P, Gasior, P, Hakola, A, Rubel, M, Fortuna, E, Kolehmainen, J & Tervakangas, S 2017, 'Interaction of candidate plasma facing materials with tokamak plasma in COMPASS', Journal of Nuclear Materials, vol. 493, pp. 102-119. https://doi.org/10.1016/j.jnucmat.2017.06.009

Interaction of candidate plasma facing materials with tokamak plasma in COMPASS. / Matějíček, Jiří; Weinzettl, Vladimír; Macková, Anna; Malinský, Petr; Havránek, Vladimír; Naydenkova, Diana; Klevarová, Veronika; Petersson, Per; Gasior, Pawel; Hakola, Antti; Rubel, Marek; Fortuna, Elzbieta; Kolehmainen, Jukka; Tervakangas, Sanna.

In: Journal of Nuclear Materials, Vol. 493, 01.09.2017, p. 102-119.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Interaction of candidate plasma facing materials with tokamak plasma in COMPASS

AU - Matějíček, Jiří

AU - Weinzettl, Vladimír

AU - Macková, Anna

AU - Malinský, Petr

AU - Havránek, Vladimír

AU - Naydenkova, Diana

AU - Klevarová, Veronika

AU - Petersson, Per

AU - Gasior, Pawel

AU - Hakola, Antti

AU - Rubel, Marek

AU - Fortuna, Elzbieta

AU - Kolehmainen, Jukka

AU - Tervakangas, Sanna

PY - 2017/9/1

Y1 - 2017/9/1

N2 - The interaction of tokamak plasma with several materials considered for the plasma facing components of future fusion devices was studied in a small-size COMPASS tokamak. These included mainly tungsten as the prime candidate and chromium steel as an alternative whose suitability was to be assessed. For the experiments, thin coatings of tungsten, P92 steel and nickel on graphite substrates were prepared by arc-discharge sputtering. The samples were exposed to hydrogen and deuterium plasma discharges in the COMPASS tokamak in two modes: a) short exposure (several discharges) on a manipulator in the proximity of the separatrix, close to the central column, and b) long exposure (several months) at the central column, aligned with the other graphite tiles. During the discharges, standard plasma diagnostics were used and a local emission of spectral lines in the visible near ultraviolet regions, corresponding to the material erosion, was monitored. Before and after the plasma exposures, the sample surfaces were observed using scanning electron microscopy, the coatings thickness was measured using Rutherford backscattering spectroscopy, and the concentration profiles of hydrogen and deuterium were measured by elastic recoil detection analysis. The uniformity of the coatings and their thickness was verified before the exposure. After the exposure, no reduction of the thickness was observed, indicating the absence of ‘global’ erosion. Erosion was observed only in isolated spots, and attributed to unipolar arcing. Slightly larger erosion was found on the steel coatings compared to the tungsten ones. Incorporation of deuterium in a thin surface layer was observed, in dependence on the exposure mode. Additionally, boron enrichment of the long-exposure samples was observed, as a result of the tokamak chamber boronization.

AB - The interaction of tokamak plasma with several materials considered for the plasma facing components of future fusion devices was studied in a small-size COMPASS tokamak. These included mainly tungsten as the prime candidate and chromium steel as an alternative whose suitability was to be assessed. For the experiments, thin coatings of tungsten, P92 steel and nickel on graphite substrates were prepared by arc-discharge sputtering. The samples were exposed to hydrogen and deuterium plasma discharges in the COMPASS tokamak in two modes: a) short exposure (several discharges) on a manipulator in the proximity of the separatrix, close to the central column, and b) long exposure (several months) at the central column, aligned with the other graphite tiles. During the discharges, standard plasma diagnostics were used and a local emission of spectral lines in the visible near ultraviolet regions, corresponding to the material erosion, was monitored. Before and after the plasma exposures, the sample surfaces were observed using scanning electron microscopy, the coatings thickness was measured using Rutherford backscattering spectroscopy, and the concentration profiles of hydrogen and deuterium were measured by elastic recoil detection analysis. The uniformity of the coatings and their thickness was verified before the exposure. After the exposure, no reduction of the thickness was observed, indicating the absence of ‘global’ erosion. Erosion was observed only in isolated spots, and attributed to unipolar arcing. Slightly larger erosion was found on the steel coatings compared to the tungsten ones. Incorporation of deuterium in a thin surface layer was observed, in dependence on the exposure mode. Additionally, boron enrichment of the long-exposure samples was observed, as a result of the tokamak chamber boronization.

UR - http://www.scopus.com/inward/record.url?scp=85020041707&partnerID=8YFLogxK

U2 - 10.1016/j.jnucmat.2017.06.009

DO - 10.1016/j.jnucmat.2017.06.009

M3 - Article

AN - SCOPUS:85020041707

VL - 493

SP - 102

EP - 119

JO - Journal of Nuclear Materials

JF - Journal of Nuclear Materials

SN - 0022-3115

ER -

Matějíček J, Weinzettl V, Macková A, Malinský P, Havránek V, Naydenkova D et al. Interaction of candidate plasma facing materials with tokamak plasma in COMPASS. Journal of Nuclear Materials. 2017 Sep 1;493:102-119. https://doi.org/10.1016/j.jnucmat.2017.06.009