Corrigendum and Addendum: Helium flux effects on bubble growth and surface morphology in plasma-facing tungsten from large-scale molecular dynamics simulations (2019 Nucl. Fusion 59 066035)

Hammond, Karl D.; Lee, Brandon F.; Naeger, Ian V.; Widanagamaachchi, Wathsala; Lo, Li-Ta; Maroudas, Dimitrios; Wirth, Brian D.

doi:10.1088/1741-4326/abb2d3

Cited by 12 publications

(4 citation statements)

References 5 publications

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“…These nanotendrils are the precursor to the surface nanostructure that eventually grows to form the fuzz-like structure on the PFC surface [5,8,[23][24][25]. Additionally, subsurface bubble dynamics [26][27][28][29][30], dislocation loop punching [17,31,32], bubble bursting, and surface crater formation [17,[33][34][35] play important roles in the early stages of the nanotendril growth process.…”

Section: Introductionmentioning

confidence: 99%

Effects of surface vacancy-adatom pair formation on PFC tungsten surface morphological response

et al. 2023

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We report a simulation study of the effect of He-irradiation-induced surface vacancy-adatom pair formation on the surface morphological evolution of plasma-facing component (PFC) tungsten and examine a number of factors that impact such evolution. Our analysis is based on self-consistent dynamical simulations according to an atomistically-informed, continuum-scale surface evolution model that has been developed following a hierarchical multiscale modeling strategy and can access the spatiotemporal scales of relevance to fuzz formation. The model accounts for the flux of surface adatoms generated as a result of the surface vacancy-adatom pair formation effect upon He implantation, which contributes to the anisotropic growth of surface nanostructural features due to the different rates of adatom diffusion along and across step edges of islands on the tungsten surface. We have carried out atomic-scale computations of optimal diffusion pathways along and across island step edges on the W(110) surface and calculated Ehrlich-Schwoebel (ES) barriers in adatom diffusion along and across such step edges. This aspect of surface adatom diffusion contributes to anisotropic surface atomic fluxes, terrace and step diffusive currents, and has been incorporated into our PFC surface evolution model, which predicts the formation of preferentially aligned nanoridge stripe patterns on the PFC surface. We establish that these anisotropic diffusive currents accelerate nanotendril growth on the PFC surface and the onset of surface nanostructure pattern formation. We also explore systematically the dependence of the PFC surface morphological response on the surface temperature and He ion incident flux, characterize in detail the resulting surface topographies and growth kinetics, and compare the predicted surface morphologies with experimental observations. Our simulation predictions for the emerging surface nanostructure patterns under certain plasma exposure conditions are consistent with experimental findings in the literature.

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Section: Introductionmentioning

confidence: 99%

Effects of surface vacancy-adatom pair formation on PFC tungsten surface morphological response

et al. 2023

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“…In contrast, bubble rupture at the surface causes recession of the surface. Figure 9 shows a visualization of snapshots from the top view for large-scale, long-term MD simulations reported by Hammond et al [74,115]. Surface islands and relatively large holes can be clearly seen from this image.…”

Section: Evolution Of Surface Morphology and Fuzz Formationmentioning

confidence: 91%

Modeling tungsten response under helium plasma irradiation: a review

Yang¹,

Fan²

2022

Plasma Sci. Technol.

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Tungsten, a leading candidate for plasma facing materials (PFM) in future fusion devices, will be exposed to high-flux low-energy helium plasma under the anticipated fusion operation conditions. In the past two decades, experiments have revealed that exposure to helium plasma strongly modified the surface morphology and hence the sputtering, thermal and other properties of tungsten, posing a serious danger to the performance and the lifetime of tungsten and the steady-state operation of plasma. In this article, we provide a review of modeling and simulation efforts on the long-term evolution of helium bubbles, surface morphology, and property changes of tungsten exposed to low-energy helium plasma. The current gap and outstanding challenges to establish a predictive modeling capability for dynamic evolution of PFM are discussed.

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“…Among those potentials, the most reliable parametrization is the Juslin–Wirth (JW) potential parametrization, which is based on the embedded-atom method (EAM) potential of Finnis and Sinclair with subsequent short-range modifications by Ackland and Thetford and further extreme-short-range modifications by Juslin and Wirth . This potential parametrization has been used successfully in plasma-exposed tungsten models under various plasma exposure conditions and has been employed in large-scale MD simulations to investigate the evolution of the near-surface region of PFC tungsten under He irradiation conditions that approach typical fusion reactor operating conditions. ,,, Also, we have used the JW parametrization in our recent study of the elastic properties of PFC tungsten; hence, predictions of tungsten elastic properties by the SNAP and JW parametrizations merit a proper comprehensive comparison before setting out to explore mechanical behavior beyond the elastic regime. In addition, we have compared these interatomic potential results with predictions from first-principles density functional theory (DFT) calculations within the quasi-harmonic approximation (DFT-QHA).…”

Section: Methodsmentioning

confidence: 99%

Molecular-Dynamics Analysis of the Mechanical Behavior of Plasma-Facing Tungsten

Weerasinghe

Martínez

Wirth

et al. 2023

ACS Appl. Mater. Interfaces

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We report a systematic computational analysis of the mechanical behavior of plasma-facing component (PFC) tungsten focusing on the impact of void and helium (He) bubble defects on the mechanical response beyond the elastic regime. Specifically, we explore the effects of porosity and He atomic fraction on the mechanical properties and structural response of PFC tungsten, at varying temperature and bubble size. We find that the Young modulus of defective tungsten undergoes substantial softening that follows an exponential scaling relation as a function of matrix porosity and He atomic content. Beyond the elastic regime, our high strain rate simulations reveal that the presence of nanoscale spherical defects (empty voids and He bubbles) reduces the yield strength of tungsten in a monotonically decreasing fashion, obeying an exponential scaling relation as a function of tungsten matrix porosity and He concentration. Our detailed analysis of the structural response of PFC tungsten near the yield point reveals that yielding is initiated by emission of dislocation loops from bubble/matrix interfaces, mainly 1/2⟨111⟩ shear loops, followed by gliding and growth of these loops and reactions to form ⟨100⟩ dislocations. Furthermore, dislocation gliding on the ⟨111⟩{211} twin systems nucleates 1/6⟨111⟩ twin regions in the tungsten matrix. These dynamical processes reduce the stress in the matrix substantially. Subsequent dislocation interactions and depletion of the twin phases via nucleation and propagation of detwinning partials lead the tungsten matrix to a next deformation stage characterized by stress increase during applied straining. Our structural analysis reveals that the depletion of twin boundaries (areal defects) is strongly impacted by the density of He bubbles at higher porosities. After the initial stress relief upon yielding, increase in the dislocation density in conjunction with decrease in the areal defect density facilitates the initiation of dislocation-driven deformation mechanisms in the PFC crystal.

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Corrigendum and Addendum: Helium flux effects on bubble growth and surface morphology in plasma-facing tungsten from large-scale molecular dynamics simulations (2019 Nucl. Fusion 59 066035)

Cited by 12 publications

References 5 publications

Effects of surface vacancy-adatom pair formation on PFC tungsten surface morphological response

Effects of surface vacancy-adatom pair formation on PFC tungsten surface morphological response

Modeling tungsten response under helium plasma irradiation: a review

Molecular-Dynamics Analysis of the Mechanical Behavior of Plasma-Facing Tungsten

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