Erosion yields of deposited beryllium layers

Erosion yields of various Be surfaces exposed to deuterium plasma, including polycrystalline Be (PC-Be), magnetron and thermionic vacuum arc deposited surfaces, and in situ plasma-deposited Be layers on Be (DP-Be/Be) and on graphite (DP-Be/C) targets, are measured in the linear divertor plasma simulator PISCES-B. It is observed that the enhanced erosion (∼3 times higher than PC-Be) of DP-Be/Be occurs at sample temperature Ts ∼ 310 K, while DP-Be/Be possesses the same yield as PC-Be at a higher Ts ∼ 570 K. The erosion yield of DP-Be/C is found to be slightly decreased at Ts ∼ 850 K. This is consistent with the more effective formation of Be2C at higher Ts, which has a higher surface binding energy than Be. It has been identified from spectroscopic measurements that Be is also eroded as BeD.