Hydrogen release and retention from porous graphite

Rai, A.; Schneider, R.; Warrier, M.

doi:10.1016/j.jnucmat.2007.08.013

Cited by 11 publications

(14 citation statements)

References 27 publications

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“…In the present work a porous graphite structure [8,15] is created and the effect of hydrogen isotope mixing during the simultaneous bombardment of H and D ion beams having overlapping and non-overlapping profiles is studied.…”

Section: Experimental Observations By Chiu Et Almentioning

confidence: 99%

“…A 3D multi-scale model has been developed to model the hydrogen isotope reactivediffusive transport in porous graphite [8,9]. The two-region model developed by Haasz et al [10] has been implemented distinguishing the atomic and molecular transport processes within the bulk and surface region on the graphite crystallites.…”

Section: Description Of the 3d Kmc Modelmentioning

confidence: 99%

“…For samples having less internal porosity mixing is very low. Therefore the internal structure of graphite, which affects the diffusion coefficient [4][5][6][7] and consequently molecule formation and atomic re-emission [8,9], plays the most crucial role for the H,D mixing. A new mechanism based on the KMC and SDTrimSP simulation is proposed to explain the experimental data.…”

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confidence: 99%

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Modeling of hydrogen isotope exchange from porous graphite

Rai

Schneider

Mutzke

et al. 2012

Nuclear Instruments and Methods in Physics Research Section B:

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A 3D Kinetic Monte Carlo (KMC) model has been used to study the hydrogen isotope exchange from porous graphite at a single granule length scale (micrometers).The present KMC model is part of a previously reported multi-scale model developed by the authors [1]. SDTrimSP [2,3] simulations have been carried out and the results have been used to get some of the input parameters for the KMC where the diffusive-reactive aspect of H and D are studied. These SDTrimSP calculations show that the incident energetic ion beams lead to the development of inter-connected pores in the graphite sample. In the presence of these connected pores hydrogen molecule formation is not a local process. It takes place throughout the implantation zone and not only at the end of the ion range. For samples having less internal porosity mixing is very low. Therefore the internal structure of graphite, which affects the diffusion coefficient [4][5][6][7] and consequently molecule formation and atomic re-emission [8,9], plays the most crucial role for the H,D mixing. A new mechanism based on the KMC and SDTrimSP simulation is proposed to explain the experimental data.

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Section: Experimental Observations By Chiu Et Almentioning

confidence: 99%

Section: Description Of the 3d Kmc Modelmentioning

confidence: 99%

mentioning

confidence: 99%

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Modeling of hydrogen isotope exchange from porous graphite

Rai

Schneider

Mutzke

et al. 2012

Nuclear Instruments and Methods in Physics Research Section B:

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“…The idea is to use the insights gained from the microscopic models (MD or ab-initio methods) for modeling the transport at the meso-scale and further at the macro-scale in order to understand the physical processes contributing to macroscopic transport. The 3D multi-scale model developed by Warrier et al [10] to simulate the "trace atom diffusion" has been improved to model the hydrogen reactive-diffusive transport (with inclusion of Küppers cycle, thermal annealing and other reactions) in porous graphite [1]. A continuous influx of hydrogen atoms determined by the flux of the ion beam has been implemented.…”

Section: Description Of 3d Kmc Modelmentioning

confidence: 99%

“…

Abstract: A multi-scale model has been developed to study the hydrogen retention [1] and chemical erosion of porous graphite. To model the chemical erosion process due to thermal hydrogen ions, Küppers cycle [2,3] has been introduced.

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Dynamic Monte-Carlo modeling of hydrogen retention and chemical erosion from Tore Supra deposits

Rai

Schneider

Warrier

et al. 2009

Journal of Nuclear Materials

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A multi-scale model has been developed to study the hydrogen retention [1] and chemical erosion of porous graphite. To model the chemical erosion process due to thermal hydrogen ions, Küppers cycle [2,3] has been introduced. The model is applied to study hydrogen transport in deposits collected from the leading edge of neutralizers of Tore Supra. The effect of internal structure on chemical erosion is studied. The MD study [4] shows that the experimentally observed decrease of erosion yield at higher fluxes is due to the decrease of carbon collision cross section at a surface due to shielding by hydrogen atom already present on the surface. Inspired by this study, a simple multi-scale model is developed to describe the flux dependence of chemical erosion. The idea is to use the local chemistry effect from the Küppers model to calculate the hydrocarbon molecule formation process and then to find the release probability of the produced hydrocarbon based on the purely geometrical constraints. The model represents quite well the trends in experimental data.

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