In-situ assessment of the emissivity of tungsten plasma facing components of the WEST tokamak

0539284 - ÚFP 2021 RIV NL eng J - Journal Article
Gaspar, J. - Aumeunier, M.-H. - Le Bohec, S. - Rigollet, F. - Brezinsek, S. - Corre, Y. - Courtois, X. - Dejarnac, Renaud - Diez, M. - Dubus, G. - Fedorczak, N. - Houry, M. - Moncada, V. - Moreau, P. - Pocheau, C. - Talatizi, C. - Tsitrone, E.
In-situ assessment of the emissivity of tungsten plasma facing components of the WEST tokamak.
Nuclear Materials and Energy. Roč. 25, December (2020), č. článku 100851. E-ISSN 2352-1791
EU Projects: European Commission(XE) 633053 - EUROfusion
Institutional support: RVO:61389021
Keywords : heat-flux estimation * infrared thermography * divertor * W emissivity * Infrared thermography * Heat flux decay width * In-situ measurement
OECD category: Fluids and plasma physics (including surface physics)
Impact factor: 2.320, year: 2020
Method of publishing: Open access
https://www.sciencedirect.com/science/article/pii/S2352179120301198?via%3Dihub

In this paper, a method was developed to estimate in-situ the emissivity of the W-coated graphite divertor tiles in the WEST tokamak. This method is based on the double heating method and take advantages of the divertor temperature increase after successive plasma experiments due to the inertial behavior of the plasma facing components. Photonic calculations have been used to disentangle the emitted and the reflected parts in the measured radiances from the infrared system. The uncertainty as well as the robustness of the method have been investigated thanks to the wide IR and thermocouple coverage in the WEST divertor. The results show strong variation of the emissivity along the divertor W surfaces with a factor 4 variation after the experimental campaigns including 18.3 GJ and about 21 000 s of cumulated injected energy and duration, respectively. Finally, the implication of a non-uniform emissivity on heat flux estimation from IR measurements is discussed, showing that non-uniform emissivity must be considered to obtain an accurate heat flux decay width.
Permanent Link: http://hdl.handle.net/11104/0316975