Investigation of transient melting of tungsten by ELMs in ASDEX Upgrade

0482351 - ÚFP 2018 RIV SE eng J - Journal Article
Krieger, K. - Sieglin, B. - Balden, M. - Coenen, J.W. - Göths, B. - Laggner, F. - de Marné, P. - Matthews, G.F. - Nille, D. - Rohde, V. - Dejarnac, Renaud - Faitsch, M. - Giannone, L. - Herrmann, A. - Horáček, Jan - Komm, Michael - Pitts, R.A. - Ratynskaia, S. - Thorén, E. - Tolias, P.
Investigation of transient melting of tungsten by ELMs in ASDEX Upgrade.
Physica Scripta. T170, December (2017), č. článku 014030. ISSN 0031-8949. E-ISSN 1402-4896.
[PFMC 2017: 16th International Conference on Plasma-Facing Materials and Components for Fusion Applications. Düsseldorf, 16.05.2017-19.05.2017]
EU Projects: European Commission(XE) 633053 - EUROfusion
Institutional support: RVO:61389021
Keywords : plasma-facing components * tungsten * melting * edge-localized modes
OECD category: 1.3 Physical sciences
Impact factor: 1.902, year: 2017
http://iopscience.iop.org/article/10.1088/1402-4896/aa8be8

Repetitive melting of tungsten by power transients originating from edge localized modes (ELMs) has been studied in the tokamak experiment ASDEX Upgrade. Tungsten samples were exposed to H-mode discharges at the outer divertor target plate using the Divertor Manipulator II system. The exposed sample was designed with an elevated sloped surface inclined against the
incident magnetic field to increase the projected parallel power flux to a level were transient melting by ELMs would occur. Sample exposure was controlled by moving the outer strike point to the sample location. As extension to previous melt studies in the new experiment both the current flow from the sample to vessel potential and the local surface temperature were measured
with sufficient time resolution to resolve individual ELMs. The experiment provided for the first time a direct link of current flow and surface temperature during transient ELM events. This allows to further constrain the MEMOS melt motion code predictions and to improve the validation of its underlying model assumptions. Post exposure ex situ analysis of the retrieved samples confirms the decreased melt motion observed at shallower magnetic field line to surface angles compared to that at leading edges exposed to the parallel power flux.
Permanent Link: http://hdl.handle.net/11104/0277840