The effect of Ar+ impurity on W nano-fuzz growth over polycrystalline W targets

The use of extrinsic impurities, such as neon (Ne), nitrogen (N2) and argon (Ar) can generate the radiative cooling of the divertor plasma during deuterium-tritium (D-T) operations in a fusion reactor. In this study, we report on the effect of 50 eV Ar+ ions on W nano-fuzz growth over tungsten (W) targets under large-flux (2.6 × 1022/m2⋅s) helium (He) and Ar ion irradiations. Our measurements show that the serious surface erosion of W divertor is formed due to Ar+ sputtering, and Ar+ sputtering process can significantly suppress the W nano-fuzz growth and decrease the diameter of W nano-fuzz. During Ar+ sputtering microns-sized clusters have been formed over W targets, and our analysis indicates that the surface migration and redeposition of W atoms resulting from sputtering can lead to a significant change in the surface microstructure of W targets.