Measurement of Hydrogen Permeation Fluxes Through Tungsten Deposition Layer Growing by Hydrogen Plasma Sputtering and Observation of Microstructure

Hydrogen isotope behavior, especially permeation and retention, at the first wall is important for the safety and fuel sufficiency of fusion reactors. This study focuses on the deposition layer formed on the first wall by sputtered particles. Hydrogen permeation flux was measured under the co-deposition environment of hydrogen and tungsten, and the microstructure of the deposition layer was observed by a transmission electron microscope. Then the relationship between the observed hydrogen permeation behavior and the formation of the deposition layer was evaluated. The results showed that the deposited layers had three different microstructures and that the permeation flux decreased with its formation. However, it was concluded that the permeation behavior could be evaluated simply by the increase in the thickness of the deposited layer and that there was no clear effect of the different structures on the permeation behavior.