Performance of Eurofer97 under deuterium plasma exposure with seeded impurities at elevated temperature

Eurofer97, P92 and Fe samples were exposed simultaneously in the linear plasma device PSI-2 to deuterium plasma and with addition of He, Ar or Kr at elevated temperature in the range of 800-950 K. Samples were exposed to plasma with an incident ion energy of 60-80 eV and an incident ion fluence of 5 x 10(25)m(-2). Surface morphology investigation of exposed samples reveals formation of fuzz-like structures on the surface steels when exposed to D and D+He plasma. Tungsten enrichment on the surface of the steels was observed after all exposures, but the average tungsten concentration varied from 4 to 18 at.%, depending on plasma composition. The highest tungsten enrichment on the surface was observed for samples exposed to D+He plasma. Addition of He to the plasma increased D retention, which was attributed to near-surface bubble formation, confirmed by transmission electron microscopy studies.