Blister evolution with fluence and temperature of deuterium plasma exposed tungsten

Tungsten (W) is a candidate material for plasma-facing components in fusion devices such as ITER and DEMO. Its hydrogen retention behavior and the surface morphology after plasma exposure were investigated extensively in the past for a wide range of exposure parameters (flux, fluence, temperature, ion energy) and for various W grades. However, up to now no general understanding with predictive capability exists and many detail questions are still waiting to be answered. Some of these questions deal with the blistering phenomenon of hot-rolled W. The appearance of blisters is proposed to be correlated with an increase of the hydrogen retention [1] and, therefore, the amount of blistering should be known for the retention estimations. In particular, the generation process of blisters, their evolution with fluence/time as well as the distribution in size and depth need to be studied.