Speaker
Description
The WEST (W -for tungsten- Environment in Steady-state Tokamak) tokamak, is based on an upgrade of the Tore Supra machine [1]. It consists in implementing an actively cooled tungsten divertor for testing high heat flux technology. Beside the presently tested ITER divertor technology (i.e. W-monoblock), the WEST team has also devoted time, in collaboration with ASIPP (China), into the development of an alternative attractive design for actively cooled W/Cu PFCs capable to sustain heat loads close to monoblock design. Within this framework, ASIPP has produced two small-scale mock-ups based on the W-armoured flat-tile concept. The mocks-up have been successfully tested in the electron beam facility JUDITH-1 (FZ-Jülich, Germany) under successive thermal cycling at 10, 15 then 20 MW/m², showing the capacity of this technology to remove heat loads over several hundreds of cycles at 20 MW/m2 without obvious indication of damage impacting the heat exhaust capability. However, the post-mortem microstructural analysis of both mock-ups showed some damage (namely, tungsten cracks perpendicular to the incident surface) below the tiles tested at 20 MW/m² [2].
This contribution focuses on thermal structural analysis performed with ANSYS and the associated experimental results. The convective heat transfer coefficients were calculated using the Nukiyama model and the mechanical properties of pure copper at high temperature were extrapolated using the Ramberg-Osgood model. The results, in good accordance with the experiments, are used to explain the defects observed on the mocks up.
The simulation confirms the good thermal performance of this technology, which is easier to manufacture than ITER like monoblocks, and far more resistant to high thermal loads than tungsten coating technology. Even though this technology has a lower critical heat flux than the monoblock concept, it shows a comparable heat exhaust capability and accordingly opens promising prospects for fusion technologies.
