29th Symposium on Fusion Technology (SOFT 2016)

O2B.3 Overview of the different processes of tungsten coating implemented into WEST tokamak

6 Sep 2016, 11:40

20m

Meeting Hall I 1st floor (Prague Congress Centre)

Board: 3

Oral F. Plasma Facing Components O2B

Speaker

Mehdi Firdaouss (CEA/IRFM)

Description

The main objective of the WEST (W Environment in Steady-state Tokamak) project is to fabricate and test an ITER-like actively cooled tungsten divertor to mitigate the risks for ITER. Concerning the others Plasma Facing Components (PFC), they will also be modified and coated with W to transform Tore Supra into a fully metallic environment. Solutions had been developed with three different suppliers, taking into account the specifications of each kind of PFC: heat flux up to 10MW/m², complex geometries including components 1m long and different substrates, CuCrZr for actively cooled PFC, graphite and CFC for other components. Plasma Vapour Deposition (PVD) is used on the main PFCs: lower divertor and bumpers (W/Mo on graphite or CFC substrate, as developed for ASDEX Upgrade), upper divertor, baffle and Vertical Displacement Event protection (W on CuCrZr substrate, new development). Vapour Plasma Deposition (VPS) technique is used on the antenna protection limiter due to their large size (W/Mo on CFC substrate, new development). For each type of coating, specifications are achieved in terms of density (>90%), homogeneity, impurity content (lower than a few percent) and absence of cracks and scratches. Several high heat flux tests have been performed on the different coating and substrates to validate each process. Consequently limits in terms of surface temperature have been defined, especially for the coating on graphite and CFC. Indeed, in this case limitations primarily come from the coating itself (around 1200°C) while for the actively cooled components it comes from the CuCrZr substrate (around 450°C). The paper gives an overview on all these different processes and associated validation programme and concludes on the adequacy of the W coating used in WEST tokamak.