The TEM Studies of Tungsten Irradiated by Hellium*

Tungsten (W) as one of the potential plasma-facing materials (PFMS) would suffer severe irradiation in nuclear fusion reactor which can results in deterioration of the related mechanical and physical properties. Understanding the irradiation effects on PFMS is then critical to improve their performances. Here, we studied the He ions irradiation effects by focusing on microstructures of the the W surfaces. As the irradiation time increased, the surface morphologies changed from smooth to full of nano-structures. TEM images show that the nano-structures contain lots of He voids, it is noted that the shapes of the he bubbles are faceted, which pointed out that the system prefers to develop low surface energy bubbles. And the nano-structures show good deformation feature although micro-carcks are developed inside.