Hydrogen trapping in carbon film: From laboratories studies to tokamak applications

Hodille, E.; Begrambekov, L. B.; Pascal, J.-Y.; Saidi, O.; Layet, J. M.; Pégouriè, B.; Grisolia, Christian

doi:10.1016/j.ijhydene.2014.09.027

Cited by 21 publications

(10 citation statements)

References 15 publications

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“…The main consequence of this high ν value is a shift of the determined binding energies by about +0.5 eV. Similar values of the pre-exponential factor ν with ν > 2 × 10 15 1/s have been observed in TPD measurements of hydrogen containing carbon films deposited in the Tore Supra tokamak [39].…”

Section: Discussionsupporting

confidence: 79%

“…Thus we used a first-order process only. Also the analysis of TPD data of carbon films deposited in tokamaks supports the presence of a first order process in the release of hydrogen [39]. Furthermore, it has been shown [40] for hydrogen implanted graphite that molecules during thermal desorption form locally, i.e., at the location where the (first) C-H bond breaking process occurs.…”

Section: Theorymentioning

confidence: 71%

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Bonding States of Hydrogen in Plasma-Deposited Hydrocarbon Films

Jacob

Dürbeck

Schwarz‐Selinger

et al. 2020

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We applied temperature-programmed desorption (TPD) spectroscopy to study the bonding of hydrogen in amorphous hydrogenated carbon (a–C:H) films. Typical hard plasma-deposited a–C:H films with an initial hydrogen content (H/(H+C)) of about 30% were used as samples. About 85% of the initial hydrogen content is released in the form of H2, the rest in the form of hydrocarbons. Using a temperature ramp of 15 K/min, release of hydrogen starts at about 600 K with a first peak at about 875 K and a broad shoulder around 1050 K. The peak positions depend on the temperature ramp. This fact was exploited to determine the pre-exponential factor for an analytic analysis of the release spectra. This analysis revealed a pre-exponential factor of ν = 1 × 10 16 1/s, which deviates significantly from the frequently assumed prefactor 1 × 10 13 1/s. This higher prefactor leads to a shift in the determined binding energies by about +0.5 eV. Standard TPD measurements with linear temperature ramps up to 1275 K were complemented by so-called “ramp and hold” experiments with linear ramps up to certain intermediate temperatures and holding the samples for different times at these temperatures. Such experiments provide valuable additional data for investigation of the thermal behavior of the investigated films. Our experiments prove that the width of the hydrogen release spectrum is determined by a distribution of binding energies rather than release kinetics or diffusive effects. This binding energy distribution has a peak at about 3.1 eV and a shoulder at higher energies extending from about 3.6 to 3.9 eV.

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Section: Discussionsupporting

confidence: 79%

Section: Theorymentioning

confidence: 71%

Bonding States of Hydrogen in Plasma-Deposited Hydrocarbon Films

Jacob

Dürbeck

Schwarz‐Selinger

et al. 2020

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“…The resulting binding energy distributions display two peaks, in the ranges 2.75-3.15 and 3.4-4.0 eV, depending on the value chosen for m. An example for m = 1 9 10 15 s -1 is shown in Fig. 8b, this latter value being close to that determined for CFC N11 [27]. (It is noticeable that-in the frame of this analysis-choosing another value for m would shift the peak position in the binding energy distribution, but would not change the outgassing rate of the samples calculated for any temperature waveform.)…”

Section: Surface Concentration and Materials Structure With Tem And supporting

confidence: 68%

Multi-technique coupling for analysis of deuterium retention in carbon fiber composite NB31

Bernard¹,

Khodja²,

Pégouriè³

et al. 2015

J Mater Sci

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International audienceThis paper presents an extensive set of measurements from complementary surface analysis techniques performed for characterizing deuterium retention in carbon fiber composite Sepcarb®NB31 subsequently to a deuterium beam exposition: adsorption isotherm measurements and Hg porosimetry to characterize the porous network, coupled deuterium beam exposure and in situ µ-NRA analysis to follow the dynamics of the penetration of the retained deuterium in the material, TEM and Raman microscopy to investigate the change in the material structure induced by ion irradiation, and finally TPD to estimate the respective proportion of deuterium retained in the surface layer and in the bulk material. The parameters extracted from this set of characterizations are introduced in a 2D Monte Carlo model which couples the propagation of deuterium and eroded carbon atoms in a network of rectilinear pores and plasma–surface interaction parameters from the SRIM code. The simulations reproduce satisfactorily the main features of the measured deuterium concentration profile and behavior of the retained deuterium amount with incident fluence, validating the physical picture of deuterium retention in CFC as due to the simultaneous implantation of the incident ions in the few 10-nm-depth layer the closest to the surface and penetration of atoms deeper in the material (several tens of microns) through the pore networ

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“…However, PFMs will be irradiated by high energy neutron (14 MeV) in combination with the high temperature (300 < T < 2000 K) (Li et al, 2017), which will inevitably induce microstructure changes such as grain boundary migration (Stepper, 1972;Vaidya and Ehrlich, 1983;Mannheim et al, 2018), and second-phase formation (voids/dislocations caused by clustering of point defects (Hasegawa et al, 2014;Hu et al, 2016), precipitates formed by the precipitation of the transmutation elements (Hasegawa et al, 2016)), etc. Besides, hydrogen (H) and its isotope escaped from the plasma can penetrate through the W surfaces and diffuse inside the bulk under plasma irradiation (El-Kharbachi et al, 2014;Hodille et al, 2014;Grisolia et al, 2015). The interaction between H and the defect microstructures may result in a set of safety issues of W such as surface blistering (Zhou H. et al, 2019), embrittlement (Louthan et al, 1972), and cracking (Ueda et al, 2005), which can notably degrade the mechanical and thermal properties of W and thus reduce its service lifetime.…”

Section: Introductionmentioning

confidence: 99%

The Effective Diffusion Coefficient of Hydrogen in Tungsten: Effects of Microstructures From Phase-Field Simulations

Xue²,

Hao³

et al. 2022

Front. Mater.

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In this work, we propose an efficient numerical method to study the effects of microstructures on the effective diffusion coefficient of the diffusion component in materials. We take the diffusion of hydrogen (H) atoms in porous polycrystalline tungsten (W) as an example. The grain structures and irradiated void microstructures are generated by using the phase-field model. The effective diffusion coefficients of H in these microstructures are obtained by solving the steady-state diffusion equation, using a spectral iterative algorithm. We first validate our simulation code for calculating the effective diffusion coefficient by using three simple examples. We then investigate the effects of the grain morphology and porosity on the effective diffusion coefficient of H in W. Regardless of whether the grain boundary is beneficial to the diffusion of H or not, it is found that the effective diffusion coefficient of H along the elongated grain direction in columnar crystals is always greater than that in isometric crystals. The increase of the porosity can significantly decrease the effective diffusion coefficient of H from the simulations of the porous W. A correlation of converting the two-dimensional (2D) effective diffusion coefficient into three-dimensional (3D) in the porous and polycrystalline W is fitted by using our simulation data, respectively. Two fitted correlations can be used to predict the synergistic effect of the porosity and grain boundary on the effective diffusion coefficient of H in W. Consequently, our simulation results provide a good reference for understanding the influence of the complex microstructures on H diffusion, and may help to design W-based materials for the fusion reactor.

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Hydrogen trapping in carbon film: From laboratories studies to tokamak applications

Cited by 21 publications

References 15 publications

Bonding States of Hydrogen in Plasma-Deposited Hydrocarbon Films

Bonding States of Hydrogen in Plasma-Deposited Hydrocarbon Films

Multi-technique coupling for analysis of deuterium retention in carbon fiber composite NB31

The Effective Diffusion Coefficient of Hydrogen in Tungsten: Effects of Microstructures From Phase-Field Simulations

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