%0 Journal Article
%A Sakamoto, Ryuichi
%A Bernard, Elodie
%A Kreter, Arkadi
%A Martin, Céline
%A Pégourié, Bernard
%A Pieters, Gregory
%A Rousseau, Bernard
%A Grisolia, Christian
%A Yoshida, Naoaki
%T Surface morphology in tungsten and RAFM steel exposed to helium plasma in PSI-2
%J Physica scripta
%V T170
%@ 1402-4896
%C Bristol
%I IoP Publ.
%M FZJ-2018-01634
%P 014062 -
%D 2017
%X Impact of the helium plasma exposure on the surface modification in tungsten and reduced activation ferritic/martensitic (RAFM) steel have been investigated on the linear plasma device PSI-2 assuming the condition of DEMO first wall. In tungsten, a nanoscale undulating surface structure, which has a periodic arrangement, is formed under low temperature conditions below fuzz nanostructure formation threshold ~1000 K. Interval and direction of the undulation shows dependence on the crystal orientation. A large variation in surface level up to 200 nm has been observed among grains at a fluence of $3\times {10}^{26}$ He m−2 showing dependence of the surface erosion rate on the crystal orientation. The {100} plane in which the undulating surface structure is not formed shows the highest erosion rate. This significant erosion is due to the multistage sputtering through impurity. In RAFM steel, sponge-like nanostructure is developed and it grows with increasing helium fluence beyond 1 μm. In the sponge-like nanostructure, a composition change from the base material is observed in which the tungsten ratio increases while the iron ratio decreases showing differences in sputtering ratio depending on the atomic mass.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000417694700007
%R 10.1088/1402-4896/aa93a2
%U https://juser.fz-juelich.de/record/844182