Molecular dynamics simulation of deuterium trapping and bubble formation in tungsten

Yang, Xueming; Hassanein, A.

doi:10.1016/j.jnucmat.2012.10.045

Cited by 38 publications

(6 citation statements)

References 30 publications

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“…Nano-bubbles formed in the vicinity of dislocation lines are assumed [14] to serve as precursors for blisters. This conclusion is supported by simulations reported in [31] and [32].…”

Section: Introductionsupporting

confidence: 83%

Multiscale modelling of the interaction of hydrogen with interstitial defects and dislocations in BCC tungsten

et al. 2017

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In a fusion tokamak, the plasma of hydrogen isotopes is in contact with tungsten at the surface of a divertor. In the bulk of the material, the hydrogen concentration profile tends towards dynamic equilibrium between the flux of incident ions and their trapping and release from defects, either native or produced by ion and neutron irradiation. The dynamics of hydrogen exchange between the plasma and the material is controlled by pressure, temperature, and also by the energy barriers characterizing hydrogen diffusion in the material, trapping and de-trapping from defects. In this work, we extend the treatment of interaction of hydrogen with vacancy-type defects, and investigate how hydrogen is trapped by self-interstitial atom defects and dislocations. The accumulation of hydrogen on dislocation loops and dislocations is assessed using a combination of density functional theory (DFT), molecular dynamics with empirical potentials, and linear elasticity theory. The equilibrium configurations adopted by hydrogen atoms in the core of dislocations as well as in the elastic fields of defects, are modelled by DFT. The structure of the resulting configurations can be rationalised assuming that hydrogen atoms interact elastically with lattice distortions and that they interact between themselves through short-range repulsion. We formulate a two-shell model for hydrogen interaction with an interstitial defect of any size, which predicts how hydrogen accumulates at defects, dislocation loops and line dislocations at a finite temperature. We derive analytical formulae for the number of hydrogen atoms forming the Cottrell atmosphere of a mesoscopic dislocation loop or an edge dislocation. The solubility of hydrogen as a function of temperature, pressure and the density of dislocations exhibits three physically distinct regimes, dominated by the solubility of hydrogen in a perfect lattice, its retention at dislocation cores, and trapping by long-range elastic fields of dislocations.

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“…Nano-bubbles formed in the vicinity of dislocation lines are assumed [14] to serve as precursors for blisters. This conclusion is supported by simulations reported in [31] and [32].…”

Section: Introductionsupporting

confidence: 83%

Multiscale modelling of the interaction of hydrogen with interstitial defects and dislocations in BCC tungsten

et al. 2017

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“…Please note that the exact, quantitative validity of binary collision approximation (BCA) codes such as SDTrimSP become questionable at energies in the eV range. However, comparing BCA calculations with molecular dynamics (MD) simulations for lowenergy hydrogen or deuterium impinging on tungsten surfaces with various orientations [14][15][16][17][18], one finds an agreement typically within a factor of 2-3 for the implantation range, and also a reasonable agreement with respect to the particle reflection yield. Please note that the MD simulations exhibit substantial variations of a similar order of magnitude as the differences to BCA due to different crystal orientations, and even due to different interatomic potentials.…”

Section: Plasma Exposurementioning

confidence: 99%

Deuterium retention in solid and liquid tin after low-temperature plasma exposure

et al. 2020

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Recently, plasma-facing components based on liquid metals were proposed for a prospective nuclear fusion reactor in order to circumvent challenges that occur for solid metal components, such as erosion lifetime, neutron embrittlement or transient overloading. One candidate material is liquid tin. We present a systematic study of the behavior of solid and liquid tin exposed to a lowtemperature deuterium plasma at temperatures between 300 and 515 K, focusing on deuterium retention and thermal release as well as on tin erosion and re-deposition. We find strong variations of deuterium depth profiles, release spectra, and erosion rates, which are correlated to dramatic changes in the surface morphology. In particular, we find evidence for massive gas bubble formation in tin, which can lead to the evolution of a thick, sponge-like layer for tin exposed to deuterium plasma just below the melting point, and to the rapid formation of a macroscopic gas pocket below liquid tin. We present evidence for strongly temperature-dependent chemical erosion of tin by deuterium plasma in the solid state. In the liquid state, a high tin erosion rate occurs, which is apparently induced by ejection of tin microdroplets. Furthermore, we observed strong plasmaassisted, low-temperature wetting of tin on tungsten near the melting point of tin. We tentatively propose the hypothesis that all of the observed effects may be influenced by tin-deuterium chemistry, e.g., the formation and de-composition of stannane molecules.

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“…Better consistency with the first-principles calculations was also achieved for the W-H interaction with Li's potential as regards the formation energies of H at different sites: tetrahedral interstitial site (TIS), octahedral interstitial site (OIS) and substitutional site (SS) (table 2). However, Juslin's potential can better describe the W-H n complex than Li's potential, and it was used very recently to model D bombardment of monocrystalline W [50]. The results obtained from Juslin's potential indicate that the formation of gas bubbles is caused by the near-surface D super-saturation region and the subsequent plastic deformation induced by the local high gas pressure.…”

Section: W-h-x Potentialmentioning

confidence: 99%

A review of modelling and simulation of hydrogen behaviour in tungsten at different scales

2014

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Tungsten (W) is considered to be one of the most promising plasma-facing materials (PFMs) for next-step fusion energy systems. However, as a PFM, W will be subjected to extremely high fluxes of low-energy hydrogen (H) isotopes, leading to retention of H isotopes and blistering in W, which will degrade the thermal and mechanical properties of W. Modelling and simulation are indispensable to understand the behaviour of H isotopes including dissolution, diffusion, accumulation and bubble formation, which can contribute directly to the design, preparation and application of W as a PFM under a fusion environment. This paper reviews the recent findings regarding the behaviour of H in W obtained via modelling and simulation at different scales.

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Molecular dynamics simulation of deuterium trapping and bubble formation in tungsten

Cited by 38 publications

References 30 publications

Multiscale modelling of the interaction of hydrogen with interstitial defects and dislocations in BCC tungsten

Multiscale modelling of the interaction of hydrogen with interstitial defects and dislocations in BCC tungsten

Deuterium retention in solid and liquid tin after low-temperature plasma exposure

A review of modelling and simulation of hydrogen behaviour in tungsten at different scales

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