ELM-induced arcing on tungsten fuzz in the COMPASS divertor region

0475064 - ÚFP 2018 RIV NL eng J - Journal Article
Matějíček, Jiří - Weinzettl, Vladimír - Vilémová, Monika - Morgan, T.W. - De Temmerman, G. - Dimitrova, Miglena - Cavalier, Jordan - Adámek, Jiří - Seidl, Jakub - Jäger, Aleš
ELM-induced arcing on tungsten fuzz in the COMPASS divertor region.
Journal of Nuclear Materials. Roč. 492, August (2017), s. 204-212. ISSN 0022-3115. E-ISSN 1873-4820.
[PSI 2016 - 22nd International Conference on Plasma Surface Interactions in Controlled Fusion Devices/22./. Roma, 30.05.2016-03.06.2016]
R&D Projects: GA ČR(CZ) GA14-12837S; GA ČR(CZ) GA15-10723S; GA MŠMT(CZ) LM2015045; GA MŠMT(CZ) LM2011026
Institutional support: RVO:61389021 ; RVO:68378271
Keywords : tungsten fuzz * arcing * COMPASS tokamak * plasma-material interaction
OECD category: Nuclear related engineering; Nuclear related engineering (FZU-D)
Impact factor: 2.447, year: 2017
http://www.sciencedirect.com/science/article/pii/S0022311517301824

Materials exposed to plasma may undergo various forms of surface modifications. Among the important phenomena for tungsten - as the prime candidate plasma-facing material for fusion devices e is a formation of helium-induced fibreform nanostructure, so-called tungsten fuzz. In this paper, we report direct observations of the interaction of the pre-prepared fuzzy tungsten surfaces with ELMy H-mode plasmas in the COMPASS tokamak as well as consequent ex-situ morphological analyses, with a particular focus on arcing as a potential erosion mechanism. Arcing events are documented from high-speed camera imaging. The sample surfaces are examined by scanning electron microscopy. Arc traces were observed on all samples, while their number was dependent on the sample position and orientation. Inside the arc traces, localized melting and densification of the original fuzz was observed, resulting in thickness reduction. The modified structure still retained some porosity and did not extend into the bulk.

Permanent Link: http://hdl.handle.net/11104/0271986