He nanobubble driven W surface growth during low-energy He ion irradiations

By using scanning electron microscopy and atomic force microscopy, we observe the microscopic surface evolution of W crystals exposed to low-energy (50 eV) He+ irradiations at the temperature of 1050 K. We find that the He+ irradiation leads to the growth and emergence of nanoscale undulations over W (110), and the surface regions with less undulations are dominating the microscopic evolution of W crystals. Analysis shows that the thermodynamic instability of W crystals irradiated is attributed to the He nanobubble driven W surface growth, which has been confirmed by our experimental measurements and He reaction rate model in W. Our study will play a crucial role in understanding the growth process of undulating surface microstructures under fusion-relevant He+ irradiations. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study observed the microscopic surface evolution of W crystals under low-energy He+ irradiations at 1050 K using scanning electron microscopy and atomic force microscopy. It was found that the He+ irradiation caused nanoscale undulations on the W (110) surface, with regions of less undulations dominating the microevolution of W crystals. Analysis indicated that the thermodynamic instability of irradiated W crystals was attributed to He nanobubble-driven surface growth.