High-flux He+ irradiation effects on surface damages of tungsten under ITER relevant conditions
Abstract
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.
- Publication:
-
Journal of Nuclear Materials
- Pub Date:
- April 2016
- DOI:
- 10.1016/j.jnucmat.2016.01.001
- Bibcode:
- 2016JNuM..471....1L