Erosion and deuterium retention of CLF-1 steel exposed to deuterium plasma

Abstract

In recent years reduced activation ferritic martensitic (RAFM) steel has been proposed as plasma-facing material (PFM) in remote regions of the first wall. This study reports the erosion and deuterium retention behaviours in CLF-1 steel exposed to deuterium (D) plasma in a linear experimental plasma system as function of incident ion energy and fluence. The incident D ion energy ranges from 30 to180 eV at a flux of 4×10 21 D/(m 2 s) up to a fluence of 10 25 D/m 2. SEM images revealed a clear change of the surface morphology as functions of incident fluence and impinging energy. The mass loss results showed a decrease of the total sputtering yield of CLF-1 steel with increasing incident fluence by up to one order of magnitude. The total sputtering yield of CLF-1 steel after 7.2×10 24 D/m 2 deuterium plasma exposure reduced by a factor of 4 compared with that of pure iron, which can be attributed to the enrichment of W at the surface due to preferential sputtering of iron and chromium. After D plasma exposure, the total deuterium retention in CLF-1 steel samples measured by TDS decreased with increasing incident fluence and energy, and a clear saturation tendency as function of incident fluence or energy was also observed.

Morphology and Sputtering of Tungsten Nitrides Coatings Exposed to Deuterium Plasma

“…1, 3, 4 shows that the surface roughness is greatest in the case of the tungsten coating. In [22], it is noted that under the current experimental parameters, with the increase of the initial surface roughness, the sputtering morphology and the surface roughness of CLF-1 steel changed to different degrees after erosion of D, which eventually led to the increase of the sputtering rate. The effect of incident D-plasma angle on the sputtering and redeposition behaviour of the material may explain this phenomenon.…”

Erosion and deuterium retention behavior of tungsten exposed to impurity-seeded deuterium plasma

“…D 2 and H 2 leaks were used to calibrate the absolute sensitivity of the mass 4 (D 2 ) and mass 3 (HD) signals (for the specific process, see Ref. [19]). D 2 and HD signals were considered in total D inventory calculation.…”

“…All plasma exposure experiments were carried out in the linear plasma device named linear experimental plasma system (LEPS, see Ref. [19]) at Lanzhou Institute of Chemical Physics. Gases are introduced into chamber with a constant pressure of 0.22 Pa.…”

“…The incident ions energy was varied by applying bias on the samples, and the relationship between the applied bias voltage and incident energy of D ions was determined according to Ref. [19]. For the pure D plasma exposure, D 3 + is the dominant ion and the D 2 + and D + ions contribute each about 3% to the total ion flux.…”

Preferential sputtering induced Cr-Diffusion during plasma exposure of WCrY smart alloys

“…The sharp decrease of the Cr partial sputter yield (figure 4b) can be ascribed to a Wenriched layer at the target surface. Similar experimental findings are presented for W-enrichment in CLF1 steel in [25] or EUROFER in [32]. Looking more closely on the numerical value for the diffusion coefficient, the following considerations were taken (see also 3.2.3): the partial sputter yields are approximately constant at 10 % of the experimental fluence and were thus used for extrapolation to 100 % of the experimental fluence to reduce computational time.…”