W nano-fuzz growth by high-flux He ion irradiation with their energy above 300 eV

Abstract

Here experiments are designed to evaluate the effects of >300 eV He+ energy and temperature on the W nano-fuzz growth over W targets. Our measurements show that increasing He+ energy from 300 eV to 750 eV leads to an increase in the W sputtering yield, thus a decrease in the thickness of W fuzz layers. Under the 750 eV He+ irradiation, the growth of W fuzz layers over W targets is not obvious due to the He+ sputtering. The irradiation temperature varying in the range of 1300 K – 1600 K is most suitable for W fuzz growth by high-flux He+ irradiation over W targets. Our analysis indicates that the deposition of sputtered W atoms onto the neighboring W nano-fibers leads to an increase in their diameter, thus affecting the W fuzz growth. When the irradiation temperature varies from 1900 K to 2700 K, the thermodynamic instability of W nano-fibers, which are metastable can be greatly increased, resulting in their shrinkage.