High-flux He+ irradiation effects on surface damages of tungsten under ITER relevant conditions

• Published in: Journal of nuclear materials Vol. 471; pp. 1 - 7
• Main Authors: Liu, Lu, Liu, Dongping, Hong, Yi, Fan, Hongyu, Ni, Weiyuan, Yang, Qi, Bi, Zhenhua, Benstetter, Günther, Li, Shouzhe
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2016
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2016.01.001

A large-power inductively coupled plasma source was designed to perform the continuous helium ions (He+) irradiations of polycrystalline tungsten (W) under International Thermonuclear Experimental Reactor (ITER) relevant conditions. He+ irradiations were performed at He+ fluxes of 2.3 × 1021–1.6 × 1022/m2 s and He+ energies of 12–220 eV. Surface damages and microstructures of irradiated W were observed by scanning electron microscopy. This study showed the growth of nano-fuzzes with their lengths of 1.3–2.0 μm at He+ energies of >70 eV or He+ fluxes of >1.3 × 1022/m2 s. Nanometer-sized defects or columnar microstructures were formed in W surface layer due to low-energy He+ irradiations at an elevated temperature (>1300 K). The diffusion and coalescence of He atoms in W surface layers led to the growth and structures of nano-fuzzes. This study indicated that a reduction of He+ energy below 12–30 eV may greatly decrease the surface damage of tungsten diverter in the fusion reactor.