@article{oai:nifs-repository.repo.nii.ac.jp:00010785,
 author = {SAKAMOTO,  Ryuichi and BERNARD, Elodie and KRETER, Arkadi and MARTIN, Celine and Pegourie, Bernard and Pieters, Gregory and Rousseau, Bernard and Grisolia, Christian and YOSHIDA,  Naoaki},
 issue = {T170},
 journal = {Physica Scripta},
 month = {Nov},
 note = {0000-0002-4453-953X, 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.},
 title = {Surface morphology in tungsten and RAFM steel exposed to helium plasma in PSI-2},
 volume = {2017},
 year = {2017}
}