Speaker
Description
The synergistic effects of tungsten exposure to combined hydrogen and helium particle fluxes need to be extensively studied for the realization of a fusion reactor project. IGP tungsten (PLANSEE) with transversal grain 12125 mm3 was sequentially irradiated with a helium (He) ion beam and hydrogen plasma generated by QSPA at a surface temperature close to room temperature (RT). The ion energy of He was 4 MeV, and the total fluence up to 2∙1024 ion/m2. Sputtering-like relief pattern of the exposed surface. Residual compressive stresses of -430 MPa were detected on the sample surface after He ion beam irradiation. An increase in the number of dislocations was observed, while the change in the lattice parameter remained negligible. High heat flux QSPA plasma streams (the duration of each pulse is 0.25 ms) with surface energy load of 0.9 MJ/m2 relevant to ITER ELM caused pronounced melting of the exposed surface. QSPA plasma irradiation resulted in partial annealing of the residual stresses, reducing them by a factor of about four to -120 MPa. The dislocation density decreased to a level close to the initial state, while the change in the lattice parameter remained negligible. Surface melting, a large crack network (up to 0.6 mm), and an intergranular crack network (up to 40 µm), as well as pores, were detected on the exposed surface after the combined irradiation. Surface changes and cross-sectional studies are discussed as well.