B. Bazylev (Sp), Forschungszentrum Karlsruhe, Eggenstein-Leopoldshafen (Germany); O.V. Ogorodnikova, J. Linke, Forschungszentrum Jülich (Germany)
The main part of divertor armour in ITER will probably be covered by tungsten (W) manufactured as thin plates of pure sintered W, W macrobrushe or W lamellae. For the strong transient events such as disruptions, ELMs and VDE the main mechanisms of damage are surface melting and melt motion, which determine the lifetime of the armour. Different tungsten armour designs have been experimentally tested with the electron beam facility JUDITH under ITER relevant off-normal conditions.
For the theoretical support of thermal shock experiments at JUDITH numerical simulations describing the melt motion at the tungsten surface have been performed for the disruption relevant condition with heat load duration up to ô =5 ms and for VDE with ô up to 0.1 s, using the fluid dynamics code MEMOS-1.5D. The code is based on the “shallow water” model supplemented with the surface tension and viscosity of molten metal as well electron beam scanning along the target surface. The volumetric energy deposition in the samples of impacting electrons of energy 120 keV is calculated using a Mont-Carlo code. Numerical simulations on the melt motion erosion for the pure sintered W, W lamellae and tungsten with 1% of La2O3 are compared with the experimental results obtained for different power loads. It is confirmed that the gradient of surface tension is the main driving force of melt motion. The behavior of tungsten under the thermal shock condition
