Surface modification and deuterium retention in rhenium doped tungsten exposed to low energy deuterium plasma

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Surface morphology and internal microstructure of tungsten (W) pre-implanted by 40 keV mass-separated helium (He) ions with different fluences at room temperature were investigated in this work. The morphology Changes of the samples were analyzed almost in situ, by repetitively examined the specified irradiation area which is marked by focused ion beam technology. As the samples were implanted by He ion with a fluence of 6 × 1020 He/m2, no He blisters or other microstructures could be found on the surface. When the fluence reaches 6 × 1021 He/m2, a large number of He blisters with the size of ~1 µm were observed on the W specimens. For the results of the subsequent deuterium plasma exposure, instead of deuterium-induced blistering, no changes on the W surface which pre-irradiated by He ion irradiation at low fluence (6 × 1020 He/m2). Surprisingly, for He ions pre-implanted W with high fluence (6 × 1021 He/m2), almost all the He blisters were cracked and their lids even peeled off. It could be attributed to the lateral stress caused by subsequent D exposure. Moreover, the size of He bubbles was also increased under subsequent deuterium exposure, suggesting that He atoms can attract D atoms. No deuterium blisters were found on these samples which were pre-implanted with high and low fluences, suggesting that He ion pre implantation can effectively inhibit the surface blistering caused by deuterium exposure.

Section: Inhibition Of Surface Blistering On W Followed By D Plasma E...mentioning

confidence: 99%

Evolution of surface morphology and helium bubble in tungsten under 40 keV helium ions implantation followed by deuterium plasma exposure

Xia¹,

Wang²,

Jiang³

et al. 2022

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“…As the exposure time increased, the lateral stress increased and reached the fracture toughness of W [29]. In this way, the cracking would occur at the weakest points in the W, such as defects [10][11][12]. Then the stress was released by plastic deformation.…”

Section: Surface Topography Of Samples After D Plasma Exposurementioning

confidence: 99%

“…As the PFMs, W will inevitably be irradiated by high-density hydrogen isotope plasma and undergo serious surface modification. Previous research has shown that surface blistering [6][7][8][9][10][11][12], melting [13] and cracking [13] occurred on the W under deuterium (D) irradiation. These are detrimental to the properties of W. In order to study the underlying physical mechanism of surface blistering and hydrogen retention in W, a series of experiments were carried out.…”

Section: Introductionmentioning

confidence: 99%

Effect of anisotropic grain boundaries on the surface blistering of tungsten induced by deuterium plasma exposure

Xia¹,

Jiang²,

Shi³

et al. 2022

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The effect of anisotropic grain boundaries on the surface microstructure changes and deuterium retention behavior in tungsten under deuterium plasma irradiation were studied. The samples named as NDW and RDW were cut from RD × TD plane and TD × ND plane of a rolled W plate (ND: normal direction, RD: rolling direction, TD: transverse direction), respectively. The results suggest that both surface morphology and deuterium retention in the RDW samples are suppressed compared to that of NDW samples for 1 h and 25 h deuterium irradiation. For 1 h exposure, the total deuterium retention in the NDW samples is about 1.6 times as much as that of RDW. However, as the exposure time increased to 25 h, the total deuterium retention in the NDW sample is two times the height of RDW sample. The experimental results show that the special grain structure of RDW can alleviate the surface morphology changes and decrease the deuterium retention in tungsten, which is interpreted by the lateral stress model of blistering.

“…Tungsten (W) is deemed as an outstanding candidate for plasma facing materials (PFMs) because of its significant advantages, such as high melting point, low sputtering yield, high thermal conductivity and low tritium retention [1,2]. As PFMs, large amounts of helium (He) impurities will be introduced by fusion reaction (D + T→ 4He + n) [3] and transmutation reaction induced by high-energy neutrons [4,5]. He atoms have low solubility, high diffusivity and self -trapping in tungsten [6][7][8].…”

Section: Introductionsmentioning

confidence: 99%

Surface modification and helium release of tungsten irradiated by 40 keV helium ions

Xia,

Jiang,

Shi

et al. 2023

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The effects of grain boundaries and surface roughness on tungsten irradiated by 40 keV He ions with a flux of 1.6 × 1017 He+/(m2s) to a fluence of 6.6 × 1021 He/m2 at room temperature were investigated. It was found that rough surfaces can suppress the surface blistering on tungsten. This may be due to the grooves appeared on rough tungsten limiting crack growth, resulting in the release of helium. However, the influence of grain boundaries on denseness of blistering was not obvious except the difference in blistering cap. The number of blister with detached cap on large grain tungsten samples (LGW, with the grain size of ~50 µm) is more than that on small grain tungsten samples (SGW, with the grain size of ~5 µm). In addition, the effect of grain boundaries on helium retention in tungsten cannot be ignored. The total He release from SGW was 2.56 × 1021 He/m2, which was smaller than the value (4.10 × 1021 He/m2) of LGW.