Blistering on tungsten surface exposed to high flux deuterium plasma

Xu, HY Haiyan; Liu, W Wendy; Luo, G.-N.; Yuan, Yue; Jia, Y.Z.; Fu, Baoqin; Temmerman, G. De

doi:10.1016/j.jnucmat.2015.12.025

Cited by 31 publications

(22 citation statements)

References 30 publications

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“…The fact that cracks were observed on flat regions of the surface, as well as that the cracks observed on top of the protrusion did not reach its cavity indicate that the appearance of cracks cannot be only explained by rupture of a blister/protrusion cap due to high internal D 2 gas pressure. It can be hypothesized that such cracks can have the same origin as the intragranular cracks associated with protrusions, since their cavities were sometimes found to be inclined to the surface [14,30,37]. shown to be formed by inter-granular cracking [6].…”

Section: Low Temperaturesmentioning

confidence: 99%

Deuterium trapping and surface modification of polycrystalline tungsten exposed to a high-flux plasma at high fluences

et al. 2017

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Deuterium (D) retention and surface modifications of hot-rolled polycrystalline tungsten (W) exposed to a low-energy (40 eV/D), high-flux (2-5×10 23 D/m 2 s) D plasma at temperatures of 380 K and 1140 K to fluences up to 1.2×10 28 D/m 2 have been examined by using nuclear reaction analysis, thermal desorption spectroscopy, and scanning electron microscopy. The samples exposed at 380 K exhibited various types of surface modifications: dome-shaped blister-like structures, stepped flat-topped protrusions, and various types of nanostructures. It was observed that a large fraction of the surface was covered with blisters and protrusions, but their average size and the number density showed almost no fluence dependence. The D depth distributions and total D inventories also barely changed with increasing fluence at 380 K. A substantial amount of D was retained in the subsurface region, which thickness correlated with the depth where the cavities of blisters and protrusions were located. It is therefore suggested that defects appearing during creation of blisters and protrusions govern the D trapping in the investigated fluence range. In addition, a large number of small cracks was observed on the exposed surfaces, which can serve as fast D release channels towards the surface, resulting in a reduction of the effective D influx into the W bulk. On the samples exposed at 1140 K no blisters and protrusions were found.However, wave-like and faceted terrace-like structures were formed instead. The concentrations of trapped D were very low (<10 5 at. fr.) after the exposure at 1140 K.

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Section: Low Temperaturesmentioning

confidence: 99%

Deuterium trapping and surface modification of polycrystalline tungsten exposed to a high-flux plasma at high fluences

et al. 2017

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“…1 & 2 in Ref. [14]). So far such protrusions have not been observed in W at comparable depth (i.e., ~200 nm) after low-flux exposure at temperatures of 300 K [18] or higher [19,33] with otherwise comparable exposure parameters.…”

Section: Resultsmentioning

confidence: 92%

“…[5,[7][8][9] and references therein). For example, it has been widely recognized that HiC features in plasma-loaded W surfaces depend strongly on exposure parameters, e.g., ion energy ion E [10], ion flux incident  [11][12][13], hydrogen isotope fluence  [11,14], and sample temperature T [15,16], etc. However, a fundamental understanding of the underlying physics of this strong dependence on experimental parameters is still missing.…”

Section: Introductionmentioning

confidence: 99%

High-flux hydrogen irradiation-induced cracking of tungsten reproduced by low-flux plasma exposure

et al. 2019

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Hydrogen-induced cracking (HiC) or blistering is a commonly observed feature in plasmaloaded material surfaces. HiC exhibits a strong dependence on the irradiation parameters, such as incident flux and fluence, particle energy, and sample temperature. However, the underlying physics of this process is still not understood. Focusing on HiC with intra-granular cavities in tungsten (W) exposed to deuterium (D) plasma, we apply a 1-dimensional flux-balance model and further propose the crucial role of the solute D distribution in the subsurface region for initiating HiC formation in plasma-loaded surfaces. Along this proposal, HiC features previously observed only under high-flux (~10 24 Dm -2 s -1 ), elevated-temperature (~500 K) exposure conditions  the co-existence of protrusions with intra-granular cavities and small-sized, dome-shaped blisters with inter-granular cracking at the surfaces  were reproduced in our low-flux experiments (~10 20 Dm -2 s -1 ) by loading W samples at low sample temperatures (230 K). The presence of protrusions in low-flux experiments is attributed to the comparable local solute D distribution in the corresponding blistering-relevant depth in both types of D plasma exposure. Applying the 1-dimensional flux-balance model in interpreting HiC formation in plasma-loaded surfaces, the present work allows us to further explore the underlying physics of HiC formation under well-defined experimental conditions.

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“…Surface cracks in some applications, including plasma-facing materials for nuclear fusion, are not preferred and could deteriorate the material's performance and lifetime. Recently, Xu et al [65] (using high-flux deuterium plasma) and Dutta et al [66] (using helium ion pulse) have shown evidence of similar surface cracking in W. While the surface cracking in W studied by Dutta et al [66] is relatively close to cracks observed in V, the ion irradiation conditions are different. The formation mechanism of such surface cracks may understood as follows: growth-induced interstitials and/or defects such as GBs, dislocations, and vacancies are almost always present in the cast refractory V as a second phase and may contribute to the appearance of cracks at GBs since they are considered to be the main regions for He dissolution and accumulation [67].…”

Section: Scanning Electron Microscopy (Sem) and Atomic Force Microscomentioning

confidence: 89%

Tuning surface porosity on vanadium surface by low energy He+ ion irradiation

Tripathi

Novakowski

Hassanein

2016

Applied Surface Science

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In the present study, we report on tuning the surface porosity on vanadium surfaces using highflux, low-energy He + ion irradiation as function of sample temperature. Polished, mirror-finished vanadium samples were irradiated with 100 eV He + ions at a constant ion-flux of 7.2  10 20 ions m-2 s-1 for 1 hour duration at constant sample temperatures in the wide range of 823-1173 K. Our results show that the surface porosity of V 2 O 5 (naturally oxidized vanadium porous structure, after taking out from UHV) is strongly correlated to the sample temperature and is highly tunable. In fact, the surface porosity significantly increases with reducing sample temperature and reaches up to ~87%. Optical reflectivity on these highly porous V 2 O 5 surfaces show ~0% optical reflectivity at 670 nm wavelength, which is very similar to that of "black metal". Combined with the naturally high melting point of V 2 O 5 , this very low optical reflectivity suggests potential application in solar power concentration technology. Additionally, this topdown approach guarantees relatively good contact between the different crystallites and avoids electrical conductivity limitations (if required). Since V 2 O 5 is naturally a potential photocatalytic material, the resulting sub-micron-sized cube-shaped porous structures could be used in solar water splitting for hydrogen production in energy applications.

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Blistering on tungsten surface exposed to high flux deuterium plasma

Cited by 31 publications

References 30 publications

Deuterium trapping and surface modification of polycrystalline tungsten exposed to a high-flux plasma at high fluences

Deuterium trapping and surface modification of polycrystalline tungsten exposed to a high-flux plasma at high fluences

High-flux hydrogen irradiation-induced cracking of tungsten reproduced by low-flux plasma exposure

Tuning surface porosity on vanadium surface by low energy He+ ion irradiation

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