The samples of tungsten were irradiated by 100keV helium ions at room temperature with different fluences ranging from 1.4×1017-3.5×1017/cm2 and then annealed at 1100℃. The interaction of helium-related defects with helium fluence was studied by means of X-ray diffraction (XRD), slow positron beam analysis (SPBA) and scanning electron microscope (SEM). The results show that the distance of crystal plane in tungsten increase after implantation. The concentration or/and size of the formed open-volume defects increase with the increase of irradiation fluence. The intergranular loose connections and voids on the surface of the sample, which were irradiated by the highest fluence of ions, reveal that there are vacancy-helium complexes or He bubbles with big size in the sample.
