Material performance of tungsten coatings under transient heat loads

Transient thermal loads in magnetic confinement experiments such as ITER have a strong impact on the material degradation of the plasma-facing components. In particular, the thermal loads for plasma-facing components in nuclear fusion devices are extraordinarily high. Within the ITER-like wall project, realized at JET, some of the plasma-facing components in the divertor region are made of tungsten-coated carbon fiber composite (CFC). These tungsten coatings were tested under ELM (edge-localized modes)-like loading conditions in an electron beam material testing facility to determine the thermal shock resistance. The failure occurrence and damage thresholds depending on base temperature and absorbed power density with special emphasis on the microstructure of the underlying CFC substrate are described in detail.