Deuterium trapping behavior in tungsten surface due to low-energy ion irradiation

Li, Cong; He, Linping; Tu, Hanjun; Shi, Liqun; Cao, Xingzhong

doi:10.1016/j.jnucmat.2023.154336

Cited by 6 publications

(3 citation statements)

References 56 publications

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“…This means that when H or He enters tungsten, it is quickly captured by the existing defects in W. Without considering the formation of new defects, the presence of H or He within existing defects inevitably leads to a decrease in the total number of available defect sites. It is also found experimentally that bubble formation occurs in tungsten exposed to low-energy D ions even without the creation of vacancies [8,34,35]. This implicates that these bubbles form when intrinsic defects within W capture solute atoms of H or He until a critical size is reached.…”

Section: Simulation Methodologymentioning

confidence: 86%

Temperature-dependent bubble growth under synergistic interactions of hydrogen and helium in tungsten

Niu,

Qin,

Suman

et al. 2024

Nucl. Fusion

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A novel theoretical model based on modified diffusion rate equations is proposed to simulate the retention of hydrogen isotopes and the dynamics of bubble growth in tungsten (W) when exposed to simultaneous hydrogen (H) and helium (He) plasma irradiations. Simulation is conducted to assess the influence of temperature as well as simultaneous H and He irradiation at an increasing fluence. Not only to develop a holistic understanding but also to substantiate simulation findings about synergy between H and He plasma irradiation, a W sample is exposed sequentially to H and He plasma at 873 K using the large-power material irradiation experimental system (LP-MIES). The topographical changes in the W sample are investigated using atomic force microscopy (AFM) after each plasma irradiation exposure sequence. Simulation results reveal that the ability of a bubble containing both H and He to trap adjacent H/He atoms is primarily governed by their individual partial pressure within the bubble. Furthermore, at elevated temperatures, the synergy between H and He significantly enhances the retention of H isotopes in W. AFM micrographs of the W sample exposed to both H and He plasma irradiation show a severely damaged and locally delaminated layer, absent in the sample exposed only to either H or He, conclusively establishing evidence of synergy between H and He irradiation effects. The average bubble radius computed using the model aligns excellently with experimentally determined values obtained through SEM/AFM analysis. The robustness of the proposed model is also assessed by comparing bubble radius and H isotopes retention at various temperatures with experimental data reported in the literature.

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Section: Simulation Methodologymentioning

confidence: 86%

Temperature-dependent bubble growth under synergistic interactions of hydrogen and helium in tungsten

Niu,

Qin,

Suman

et al. 2024

Nucl. Fusion

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“…(c) The D particles implant into the W cell. According to the experiments and simulations related to D retention inside W [3,[32][33][34][35], the maximum trapping concentration (MTC) of D particles is around 0.1%-1% due to different experimental and simulative conditions. In the current modeling, the MTC is set as 1% for the W cells that are directly irradiated by D particles in view of irradiation damage, while for the W cells that are not directly irradiated the MTC is set as 0.1%.…”

Section: Interaction Between D Particles and W Fuzzmentioning

confidence: 99%

Studies on the impacts of the pore size and shape on deuterium retention in tungsten fuzzy nanostructures

Chen,

Dai,

Yang

et al. 2024

Nucl. Fusion

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Tritium retention in plasma-facing materials is a critical issue that can significantly impact the long-term and steady-state operation of fusion devices. The experiments conducted in the laboratory device MIES have confirmed that the presence of the tungsten (W) nanostructure (called “fuzz”) leads to a substantial retention of hydrogen isotopes within W fuzz layer. This observation motivates us to conduct dedicated modelling to investigate the influence of W nanostructures on deuterium (D) retention using the three-dimensional kinetic Monte Carlo code SURO-FUZZ. The SURO-FUZZ code offers a great flexibility in generating diverse microscopic structures of the W fuzzy surface through the quartet structure generation set (QSGS) approach, which allows us to explore the effects of the pore size and shape on D retention. In this study, several different W nanostructures generated by QSGS approach are utilized to conduct a comprehensive comparison between MIES experiments and SURO-FUZZ simulations. It is demonstrated that the simulated D retention can be brought into a reasonable agreement with the experimental data. On this basis, predictive estimations of D retention on EAST and ITER have been performed with SURO-FUZZ modelling. The simulation results indicate that the total D retention induced by W fuzz remains well below the administrative limit of 700 g.

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“…These blisters not only modify the near surface microstructure, including exfoliation and cracking [16,18], but are a source of larger than expected hydrogen inventories in the divertor material. Some prior work has suggested the formation of a supersaturated layer of tungsten, where the atomic percent of hydrogen is much higher than expected given the solubility in tungsten, at higher hydrogen fluences that may lead to blister formation [13,[19][20][21] Similarly, irradiations of both ions and deuterium have shown higher retention due to trapping at ioninduced point defects like vacancies and voids [22] and can remain trapped up to high temperatures. However, tungsten exposed to pure deuterium plasmas at low energies, where the implantation energy is below the threshold energy for Frenkel pair formation, has still resulted in blister formation [14,15].…”

Section: Introductionmentioning

confidence: 98%

Dynamic formation of preferentially lattice oriented, self trapped hydrogen clusters

Cusentino,

Sikorski,

McCarthy

et al. 2023

Mater. Res. Express

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A series of MD and DFT simulations were performed to investigate hydrogen self-clustering and retention in tungsten. Using a newly develop machine learned interatomic potential, spontaneous formation of hydrogen platelets was observed after implanting low-energy hydrogen into tungsten at high fluxes and temperatures. The platelets formed along low miller index orientations and neighboring tetrahedral and octahedral sites and could grow to over 50 atoms in size. High temperatures above 600 K and high hydrogen concentrations were needed to observe significant platelet formation. A critical platelet size of six hydrogen atoms was needed for long term stability. Platelets smaller than this were found to be thermally unstable within a few nanoseconds. To verify these observations, characteristic platelets from the MD simulations were simulated using large-scale DFT. DFT corroborated the MD results in that large platelets were also found to be dynamically stable for five or more hydrogen atoms. The LDOS from the DFT simulated platelets indicated that hydrogen atoms, particularly at the periphery of the platelet, were found to be at least as stable as hydrogen atoms in bulk tungsten. In addition, electrons were found to be localized around hydrogen atoms in the platelet itself and that hydrogen atoms up to 4.2 A ̊ away within the platelet were found to be bonded suggesting that the hydrogen atoms are interacting across longer distances than previously suggested. These results reveal a self-clustering mechanisms for hydrogen within tungsten in the absence of radiation induced or microstructural defects that could be a precursor to blistering and potentially explain the experimentally observed high hydrogen retention particularly in the near surface region.

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Deuterium trapping behavior in tungsten surface due to low-energy ion irradiation

Cited by 6 publications

References 56 publications

Temperature-dependent bubble growth under synergistic interactions of hydrogen and helium in tungsten

Temperature-dependent bubble growth under synergistic interactions of hydrogen and helium in tungsten

Studies on the impacts of the pore size and shape on deuterium retention in tungsten fuzzy nanostructures

Dynamic formation of preferentially lattice oriented, self trapped hydrogen clusters

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