Tungsten coatings for application in WEST project

Abstract

The WEST (Tungsten Environment in Steady-state Tokamak) project is aimed to implement and test the ITER W divertor technology in relevant plasma operation conditions. In addition to the ITER-like W monoblock divertor target, the WEST project involves W coated CuCrZr target and W coated Fine Grain Graphite (FGG) and CFC-N11 (Carbon Fiber Composite) tiles. Combined Magnetron Sputtering and Ion Implantation (CMSII) technology was developed and applied in the framework of ITER-like wall (ILW) project at JET for W coating of CFC Dunlop 780 DMS tiles Ruset et al. (2007) [1]. The coating thickness was in the range of 10–25 µm depending on the position of the tiles in the wall. The same technology was also used for W coating of more than 1300 FGG tiles for ASDEX Upgrade tokamak. In the present paper W coatings of 12.8 µm and 20 µm deposited on PFC (Plasma Facing Components) materials used in WEST project will be analyzed. As substrate materials CFC N11, FGG samples were used. These substrate materials have different properties compared to materials used for ILW project. GDOES (Glow Discharge Optical Emission Spectrometry) and XRD (X-Ray Diffraction) measurements were used for assessment of chemical composition and structure of the coatings. The behavior of the coatings to the High Heat Flux tests (HHFT) has been investigated by using an electron beam test facility. The testing program consisted of ∼300 pulses with duration of 420 s each. The surface temperature during the tests was 1200 °C whereas the power density was about 3.5 MW/m2.

Keywords

• W coatings
• High heat flux test
• WEST project
• ITER divertor