Speaker
Cristian Ruset
(Plasma Phisics and Nuclear Fusion)
Description
Tungsten coatings deposited on carbon materials such as carbon fibre composite (CFC) or fine grain graphite (FGG) are currently used in fusion devices as armour for plasma facing components (PFC). About 1800 CFC tiles were W-coated for the ITER-like Wall at JET and more than 1300 FGG tiles were coated for the ASDEX Upgrade tokamak. At present the W coating production is on going for the first lower divertor of WEST.
The emissivity of W coatings is a key parameter required by protection systems of the W-coated PFC and also by many diagnostic tools in order to get correct values of temperature, heat loading, etc. The emissivity of tungsten is rather well known, but the literature data refer to bulk tungsten or tungsten foils and not to coatings deposited on carbon materials.
W coatings of 10 μm or 20 μm were deposited on tubes (Φ16x85x0.8 mm) made of FGG, and CFC. A hole with a diameter of 2 mm was drilled in the middle of the tube perpendicular to its axis. This hole played the role of a black body. The W-coated tube was heated up to 1200 °C by electric conduction. The emissivity was measured at the wavelengths of 1.064 μm, 1.75 μm, 3.75 μm, 4.0 μm and 4.25 μm using IR detectors.
It was found that the structure of the substrate, particularly in the case of porous CFC, has a significant influence on the emissivity values. The temperature dependence of the emissivity in the range of 600°C-1200°C and the influence of the viewing angle were investigated as well. The emissivity depends significantly on the investigating wavelength. For example 10 μm W coated Dunlop CFC at 1000°C has the emissivity of 0.63±0.07 at the wavelength of 1.064 μm while at 4.0 μm the emissivity drops to 0.25±0.07.
Co-authors
Cristian Ruset
(Plasma Phisics and Nuclear Fusion, National Institute for Laser, Plasma and Radiation Physics, Magurele-Bucharest, Romania)
Dragos Falie
(Plasma Phisics and Nuclear Fusion, National Institute for Laser, Plasma and Radiation Physics, Magurele-Bucharest, Romania)
Guy Matthews
(Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom)
Jerome Bucalossi
(IRFM, CEA Cadarache, F-13108 Saint Paul Lez Durance, France)
Klaus-Dieter Zastrow
(Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom)
Mihaela Gherendi
(Plasma Phisics and Nuclear Fusion, National Institute for Laser, Plasma and Radiation Physics, Magurele-Bucharest, Romania)
Vasile Zoita
(Plasma Phisics and Nuclear Fusion, National Institute for Laser, Plasma and Radiation Physics, Magurele-Bucharest, Romania)
Xavier Courtois
(IRFM, CEA Cadarache, F-13108 Saint Paul Lez Durance, France)
