Dynamic fuel retention in tokamak wall materials: An in situ laboratory study of deuterium release from polycrystalline tungsten at room temperature

Bisson, Régis; Markelj, S.; Mourey., O; Ghiorghiu, F; Achkasov, K.; Layet, J. M.; Roubin, P.; Cartry, Gilles; Grisolia, C.; Angot, Thierry

doi:10.1016/j.jnucmat.2015.07.028

Cited by 44 publications

(49 citation statements)

References 31 publications

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“…Further experimental details on the NRA setup and analysis can be found in the article by Markelj et al [12]. Integration of the NRA deuterium profile yields the deuterium retention within the probed depth, which agrees within less than a factor of two with the deuterium retention obtained by thermo-desorption [11].…”

Section: Methodssupporting

confidence: 57%

“…Finally, if two hydrogen isotopes reach the surface, they can recombine and form a desorbing molecule. The latter process has been shown not to be rate limiting in the experiments [11] simulated in this paper, and thus the desorption process is considered to be instantaneous in the present simulations. However, we inform the reader that the description of surface processes has been included in a recent upgrade of the MHIMS code [20].…”

Section: Mre Models: Single Trap-single Detrapping Energymentioning

confidence: 78%

“…Once the quality of its preparation was deemed satisfactory, the sample was introduced in the ultra-high-vacuum (UHV) cluster chamber setup at AMU (base pressure <4 × 10 −8 Pa) [11], where it remained in UHV conditions until the end of the implantation-thermo-desorption series.…”

Section: Methodsmentioning

confidence: 99%

“…The fluence was varied by setting the duration of ionic implantation. Then, the sample was stored at a temperature of 300 K and at a pressure of 1 × 10 −7 Pa for a storage time varying between 2 h and 135 h. The minimum storage time of 2 h was limited by the procedure allowing the retrieval of low partial pressures for D 2 and HD molecules in the thermo-desorption setup [11]. Finally, the sample temperature was increased at a rate of 1 K · s −1 while a differentially pumped quadrupole mass spectrometer was measuring in line-of-sight HD and D 2 molecules emitted by the sample.…”

Section: Methodsmentioning

confidence: 99%

“…with suitable MRE modelling (see next sections). Further experimental details on the implantation-thermo-desorption apparatus can be found in the article by Bisson et al [11].…”

Section: Methodsmentioning

confidence: 99%

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Retention and release of hydrogen isotopes in tungsten plasma-facing components: the role of grain boundaries and the native oxide layer from a joint experiment-simulation integrated approach

et al. 2017

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Fusion fuel retention (trapping) and release (desorption) from plasma-facing components are critical issues for ITER and for any future industrial demonstration reactors such as DEMO. Therefore, understanding the fundamental mechanisms behind the retention of hydrogen isotopes in first wall and divertor materials is necessary. We developed an approach that couples dedicated experimental studies with modelling at all relevant scales, from microscopic elementary steps to macroscopic observables, in order to build a reliable and predictive fusion reactor wall model. This integrated approach is applied to the ITER divertor material (tungsten), and advances in the development of the wall model are presented. An experimental dataset, including focused ion beam scanning electron microscopy, isothermal desorption, temperature programmed desorption, nuclear reaction analysis and Auger electron spectroscopy, is exploited to initialize a macroscopic rate equation wall model. This model includes all elementary steps of modelled experiments: implantation of fusion fuel, fuel diffusion in the bulk or towards the surface, fuel trapping on defects and release of trapped fuel during a thermal excursion of materials. We were able to show that a single-trap-type single-detrapping-energy model is not able to reproduce an extended parameter space study of a polycrystalline sample exhibiting a single desorption peak. It is therefore justified to use density functional theory to guide the initialization of a more complex model. This new model still contains a single type of trap, but includes the density functional theory findings that the detrapping energy varies as a function of the number of hydrogen isotopes bound to the trap. A better agreement of the model with experimental results is obtained when grain boundary defects are included, as is consistent with the polycrystalline nature of the studied sample. Refinement of this grain boundary model is discussed as well as the inclusion in the model Nuclear Fusion

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Section: Methodssupporting

confidence: 57%

Section: Mre Models: Single Trap-single Detrapping Energymentioning

confidence: 78%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…with suitable MRE modelling (see next sections). Further experimental details on the implantation-thermo-desorption apparatus can be found in the article by Bisson et al [11].…”

Section: Methodsmentioning

confidence: 99%

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Retention and release of hydrogen isotopes in tungsten plasma-facing components: the role of grain boundaries and the native oxide layer from a joint experiment-simulation integrated approach

et al. 2017

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Saturation of tungsten surfaces with hydrogen: A density functional theory study complemented by low energy ion scattering and direct recoil spectroscopy data

Piazza¹,

Ajmalghan²,

Ferro³

et al. 2018

Acta Materialia

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Herein, we investigate the saturation limits of hydrogen on the (110) and (100) surfaces of tungsten via Density Functional Theory (DFT) and complement our findings with experimental measurements. We present a detailed study of the various stable configurations that hydrogen can adopt upon the surfaces at coverage ratios starting below 1.0, up to the point of their experimental coverage ratios, and beyond. Our findings allow us to estimate that the saturation limit on each surface exists with one monolayer of hydrogen atoms adsorbed. In the case of (110) this corresponds to a coverage ratio of one hydrogen atom per tungsten atom, while in the case of (100) a full monolayer is present at a coverage ratio of 2.0. Preliminary Low Energy Ion Scattering (LEIS) and Direct Recoil Spectroscopy (DRS)measurements complement these results and tend to confirm the findings obtained by DFT. In particular, the preferred adsorption sites on both surfaces at any coverage, the reconstruction of the (100) surface and the saturation limits agree well. We show that depending on the coverage, hydrogen surface binding energies can be of the same magnitude as binding energies to defects like vacancies. As a consequence, surface effects should be included in models aiming to simulate retention and desorption of hydrogen from the bulk.

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Dynamic equilibrium of displacement damage defects in heavy-ion irradiated tungsten

et al. 2023

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Dynamic fuel retention in tokamak wall materials: An in situ laboratory study of deuterium release from polycrystalline tungsten at room temperature

Cited by 44 publications

References 31 publications

Retention and release of hydrogen isotopes in tungsten plasma-facing components: the role of grain boundaries and the native oxide layer from a joint experiment-simulation integrated approach

Retention and release of hydrogen isotopes in tungsten plasma-facing components: the role of grain boundaries and the native oxide layer from a joint experiment-simulation integrated approach

Saturation of tungsten surfaces with hydrogen: A density functional theory study complemented by low energy ion scattering and direct recoil spectroscopy data

Dynamic equilibrium of displacement damage defects in heavy-ion irradiated tungsten

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