Synergistic effects of ELMs and HHe irradiation on the degradation behavior of tungsten treated with high-energy-rate forging

Tungsten is a very promising candidate as plasma facing material of future fusion reactors. In order to meet the requirements of future fusion reactors, Y₂O₃ dispersion strengthened tungsten was processed by thermo-plastic deformation. The microstructure of the processed sample was characterized by using scanning electron microscope (SEM) equipped with electron backscattering diffraction (EBSD). The synergetic effects of neutral beam irradiation with a H/He mixture and electron beam loading similar to heat fluxes of Edge Localized Modes (ELMs) on the service performance of the processed WY₂O₃ alloy were investigated. Morphological changes, such as the crack initiation and propagation under ELM-like transient loading were also analyzed. The experimental results show that the processed tungsten exhibits a laminated microstructure which has been much refined compared to the sintered sample. Surface morphologies of the tungsten samples changed significantly after H/He neutral beam irradiation. The pre-irradiation by H/He irradiation has obviously no effect on the crack threshold of the tungsten alloy under ELMs-like thermal load. The width and depth of major cracks for different samples changed regularly with the variation of surface temperatures during H/He irradiation.