Fusion Materials Research with the GIRAFFE Experiment - Mechanical Testing under Fusion-Relevant Loads

The development of suitable materials for the highly loaded plasma facing components (PFCs) is a major challenge in the development of a future fusion power plant such as DEMO. These materials must withstand a high heat flux, exposure to an intense particle flux, consisting of hydrogen (H) and helium (He), as well as significant irradiation with fusion neutrons. These loads can lead to a deterioration of the thermo-mechanical properties of the PFC materials.
Since the individual loads influence each other, it is not sufficient to study their influence on the materials in isolation. To investigate the synergistic effects between irradiation damage, implantation of H/He, material temperature and mechanical stress, the General-Purpose Irradiated Fiber and Foil Experiment (GIRAFFE) was developed. Thin wires and foils serve as samples. These can be exposed to an H/He particle flux from a low-energy plasma source while mechanical tests are performed. At the same time, a high energy ion beam can be used to simulate the dislocation damage caused by neutrons. In addition, this beam can also be used for the targeted implantation of impurities such as H/He or carbon.
In this talk, the current status of the experiment will be introduced, in particular the testing capabilities and future upgrades. Furthermore, the first results on irradiation induced stress relaxation of tungsten are presented. In these experiments, thin tungsten wires were preloaded to 1-2 GPa and irradiated with 20.3 MeV tungsten ions while the resulting load decrease was measured.