Contribution of blistering to first wall erosion in plasma wall contact

It has been shown that for the example of Nb, formation of blisters due to He ion bombardment below 15 keV is a transient phenomenon. After a thickness corresponding to the 'Deckeldicke' has been sputtered away no further blister formation is observed. It was further shown that in the case of a broad energy and angular distribution of the incident particles blistering may be completely avoided. At very high doses a rough but regular equilibrium surface structure develops, which reflects the structure and orientation of the underlying material. (V.J.C)