Effect of transient heating loads on beryllium

•We study the effect of transient plasma loads on beryllium erosion and surface microstructure.•Beryllium targets were irradiated by plasma streams with energy of 0.5–1MJ/m2 at ∼250°C.•Under plasma loads 0.5–1MJ/m2 cracking of beryllium surface is rather slight.•Under 0.5MJ/m2 the mass loss of Be is no more than 0.2g/m2 shot and decreasing with shots number.•Under 1MJ/m2 maximum mass loss of beryllium was 3.7g/m2 shot and decreasing with shots number. Beryllium will be used as a plasma facing material for ITER first wall. It is expected that erosion of beryllium under transient plasma loads such as the edge-localized modes (ELMs) and disruptions will mainly determine a lifetime of ITER first wall. The results of recent experiments with the Russian beryllium of TGP-56FW ITER grade on QSPA-Be plasma gun facility are presented. The Be/CuCrZr mock-ups were exposed to upto 100 shots by deuterium plasma streams with pulse duration of 0.5ms at ∼250°C and average heat loads of 0.5 and 1MJ/m2. Experiments were performed at 250°C. The evolution of surface microstructure and cracks morphology as well as beryllium mass loss are investigated under erosion process.