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 0.5–1 MJ/m2 at ∼250 °C.
• Under plasma loads 0.5–1 MJ/m2 cracking of beryllium surface is rather slight.
• Under 0.5 MJ/m2 the mass loss of Be is no more than 0.2 g/m2 shot and decreasing with shots number.
• Under 1 MJ/m2 maximum mass loss of beryllium was 3.7 g/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 0.5 ms at ∼250 °C and average heat loads of 0.5 and 1 MJ/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.