Crystallographic analysis of nano-tendril bundle vs fuzz growth on tungsten exposed to helicon wave-coupled helium plasma

The propensity for nano-tendril bundle (NTB) vs widespread growth (i.e., fuzz) on polycrystalline W under varying ion energy modulation conditions, from DC to peak-to-peak of 42 eV at 13.56 MHz, is correlated with the crystal orientation underlying grains. Grains that are vicinal orientations high surface diffusivity (e.g., {101} a body centered cubic structure) exhibit NTB lower amplitude than grains low orientations, such as {100}. Adatom mobility considerations presented describe experimental observations. These results support diffusion or adatom enhanced by bombardment plays key role in morphology evolution He irradiation.