Post mortem analysis of a tungsten coated tile from the outer divertor strike point region of ASDEX upgrade

Our results confirm that the outer divertor of AUG is generally a net erosion region for tungsten, however, the strong deposition of eroded tungsten takes place close to the outer strike point (private flux region). The observations on cross-sections of the tungsten coatings revealed micro-cracks around the strike point region. These cracks are caused by thermal stresses due to periodic heating and cooling of the layer during ELMs.