The occurrence and damage of unipolar arcing on fuzzy tungsten

0450903 - ÚFP 2016 RIV NL eng J - Journal Article
Aussems, D.U.B. - Nishijima, D. - Brandt, C. - van der Meiden, H.J. - Vilémová, Monika - Matějíček, Jiří - De Temmerman, G. - Doerner, R.P. - Lopes Cardozo, N.J.
The occurrence and damage of unipolar arcing on fuzzy tungsten.
Journal of Nuclear Materials. Roč. 463, August (2015), s. 303-307. ISSN 0022-3115. E-ISSN 1873-4820.
[PLASMA-SURFACE INTERACTIONS 21: International Conference on Plasma-Surface Interactions in Controlled Fusion Devices. Kanazawa, 26.05.2014-30.05.2014]
R&D Projects: GA ČR(CZ) GA14-12837S
Institutional support: RVO:61389021
Keywords : Tungsten * fuzz * unipolar arcing * melting * fusion reactor
OECD category: Nuclear related engineering
Impact factor: 2.199, year: 2015
http://www.sciencedirect.com/science/article/pii/S0022311514005996514005996

This research investigated whether unipolar arcing in the divertor of fusion reactors is a potential cause for enhanced wear of the divertor. It was found that 1 μm of nano-fuzz growth is sufficient to initiate arcing, mainly depending on the sheath potential drop and electron density. The average mass loss rate induced by the arc was determined from mass loss measurements and found to be consistent with the value estimated from the arc current. The average arc track erosion depth was estimated by using the measured mass loss and damaged surface area and was found to be one tenth of the fuzzy layer thickness. Due to melting of the fuzzy structures the actual depth is larger and some arc tracks occasionally appeared to even reach the bulk beyond the fuzzy layer. The conclusion of this study is therefore that arcing in the divertor of future tokamaks (e.g. ITER) potentially is an important cause for surface damage and plasma pollution.
Permanent Link: http://hdl.handle.net/11104/0252230