Incident ion energy dependence of bubble formation on tungsten surface with low energy and high flux helium plasma irradiation

Tungsten (W) specimens were irradiated by low energy (<65 eV) and high flux (∼1022–23 m−2 s−1) helium plasma to investigate the incident ion energy dependence of helium bubble formation. Experimental results indicate the existence of the incident ion energy threshold for the bubble formation. The threshold energy around 15 eV could associate with the surface potential for He ions entering to the W surface.