Damage And Deposition Behaviors In Tungsten Irradiated By Hydrogen And Deuterium Ions

The development of nuclear energy is an inevitable choice for human to solve the energy problem permanently. With the designation and development of International Thermonuclear Experimental Reactor(ITER), scientists have draw much attention to fusion materials. Tungsten-based materials are the main candidate divertor materials in fusion reactor. Thus, it is crucial to study the changes of microstructure and properties of tungsten-based material caused by hydrogen ion irradiation.In this work, the damage and hydrogen deposition behavior in tungsten were studied from two aspects. Part I, deuterium ions were implanted into tungsten with an energy of 20 keV/D and flux of 3.0×1014 D/(cm2s). The relationship between deuterium concentration and fluences was obtained by measuring proton yields during implantation process; while at some fluence points, proton yields were also monitored by deuterium beam with energy of 75 keV/D and current of 0.6 μA. After, deuterium concentration changes induced by radiation damage was studied by two rounds of deuterium ion implantation with different energies and fluences. After the samples were stored for one year and two years, the static deuterium concentration were analysed by elastic recoil nuclear reaction(ERDA) method and secondary ion mass analysis(SIMS), respectively. Part II, the damages of tungsten surface irradiated by protons with energy of 10 keV and fluence of 1015-1018 H/cm2 were studied. In addition, the surface topography discrepancy between pre-irradiated and irradiated samples were observed by atomic force microscopy(AFM), scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The evolution of blister formation to rupture with increasing fluences and flux was been analysed. Also, comparing with the evolution process of blister irradiated by proton, the possible influence of blister on deuterium concentration was also discussed.According to the studies above, the conclusions were as following:(1) For 20 keV/D deuterium ion implantation, the saturated deuterium concentration in tungsten was nD/nW=44.0±2.7(at.%), and the critical fluence was 1.54×1018 D/cm2.(2) By the implantation of lower energy deuterium ions(5-13 keV/D), tungsten surface(<50 nm) has been damaged severely, and the diffusion coefficient was changed due to irradiation damage in damaged area.(3) After samples were placed for one year, the deuterium concentration was 2-4 at.% fluctuated with depth, and the maximum value was near 110 nm.(4) For 10 keV proton implantation, the size of blister increaseed with increasing fluence. At the fluence of 5×1017 cm-2, the size is about 3 μm observed by SEM.(5) Flux is an important factor to affect the size of the blister, and blister size increase with flux.