Effect of Helium Ions Irradiation at High Temperature on Surface Morphology of Tungsten
Tungsten(W)is considered as one of the most promising plasma facing materials for fu-sion devices due to its excellent properties such as high melting point,high thermal conductivity,high sputtering threshold and low hydrogen isotope retention.In this study,high-purity tungsten blocks are irra-diated by helium(He)ions at temperatures＞2000 K,and the effect of changes in irradiation parameters on the evolution of the W surface morphology is investigated.The results show that at 2300 K,the sur-face of the W samples shows a significant swelling morphology due to the growth of helium bubbles.As the ion fluence increases,the helium bubbles rupture,accompanied by the appearance of surface holes,and further surface swelling gradually develops into cross-linked coral-like tungsten nanofilament struc-tures;With the increase of ion energy,the depth of helium ions injected into the W material increases,which promotes the growth of surface tungsten filament-like structures.When the temperature is changed from 2100 K to 2400 K,the temperature increase enhances the rapid diffusion of self-interstitial tungsten atoms on the surface,which leads to the suppression of the surface swelling and tungsten filament-like structure growth behavior,and even the degradation of the tungsten filament-like structure.The increase in both helium ion fluence and ion energy promotes the formation and evolution of tungsten filament-like structures on the surface of W materials after high-temperature He ion irradiation in the adopted range of experimental parameters,while the increase in temperature shows the opposite trend.
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