Erosion and deuterium retention investigation of mixed W-Be layer on Be in experiments on plasma disruption simulation

The mixed W-Be layers were prepared by depositing of Be and W atoms on Be substrate under simultaneous sputtering of Be and W targets by 20 keV Ar+-ions. The thickness of the deposited mixed W-Be layer was similar to 500 nm. The element composition analysis of these layers showed that mixed layer contains up to 35 at.% W, up to 35 at.% Be and up to 30 at.% O. The W-Be films on Be were irradiated by pulsed deuterium plasma flux in the electrodynamic plasma MKT-accelerator at the deuterium plasma concentration of 10(21) m(-3), maximal ion energy of (1-2) keV and with the energy flux density of 0.2 MJ/m(2) per pulse. The pulse duration was equal to 60 mus. After irradiation by two plasma pulses the W-Be film is melted and removed completely from the local surface areas. The element distributions in a mixed layer after an effect of the pulsed plasma ate essentially changed. For the surface areas with the removed film the Be concentration is about 75 at.%, W - about 15 at.%, O - about 10 at.% and the penetration of W and O atones up to 1000 nm in depth of Be substrate is observed. For the surface areas with the retained melted film the Be surface concentration increase up to 90 at.%, tungsten and oxygen concentration decrease about 2-3 times. The method of Elastic Recoil Detection Analysis was used to study D retention. The integral deuterium concentrations ate equal to 0.6 10(20) and 2.2 10(20) m(-2) tot the removed him areas and for the retained melted film ones, correspondingly. Consequently, deposited W-Be film promotes the essential reduction of D retention in Be substrate. Transmission electron microscopy was used to study the erosion product size distribution. The erosion products were collected an basalt filter fibers located in a shadow of the pulsed plasma flux around the exposed W-Be film target. The erosion product size distribution has two maxima located in the ranges 0.1-0.2 mum and 2.5-5.0 mum.