Deuterium inventory in Tore Supra: Contribution of carbon deposits outgassing

Panayotis, S.; Pégouriè, B.; Caprin, E.; Douai, D.; Hatchressian, Jean-Claude; Negrier, V.; Pascal, J.-Y.; Vartanian, S.; Bucalossi, J.; Monier‐Garbet, P.

doi:10.1016/j.jnucmat.2013.01.232

Cited by 12 publications

(15 citation statements)

References 14 publications

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“…The power-law release occurs later (∼ 10 3 s) than in Grisolia's work (∼ 10 s) due to a volumetric recombination term introduced by Grisolia in (1). Nevertheless, the timescale for which powerlaw dependencies occur is in agreement with timescale experimentally observed between plasma discharges [4].…”

Section: Hydrogen Desorption From Materials Surface Vs Hydrogen Desorpsupporting

confidence: 88%

“…3b and fig. 3c is due to the release of the excess of free hydrogen near the surface and has been observed experimentally in graphite [3,4]. …”

Section: Hydrogen Desorption From Materials Surface Vs Hydrogen Desorpmentioning

confidence: 71%

“…In the context of long-time plasma exposure, the experimental outgassing hydrogen flux from graphite walls loaded with deuterium follows a power-law ∼ t −0.7±0.1 during long off-plasma periods [3,4]. Experiments performed on JET in ITER-like wall configuration have shown that the evolution in time of hydrogen outgassing flux from vessel components follows a similar power-law ∼ t −0.8 [5].…”

Section: Introductionmentioning

confidence: 99%

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Long‐Term Hydrogen Outgassing from Plasma Facing Components

Guterl

Smirnov

Krasheninnikov

2014

Contrib. Plasma Phys.

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The time evolution of hydrogen outgassing fluxes from plasma facing components(PFCs) in tokamaks at room temperature is investigated using a diffusion-reaction model with a single trap in the bulk of PFCs material. The release of hydrogen is surface-limited or diffusion-limited depending on properties of material and surface processes. In both surface and diffusion-limited regimes, the long-term decrease of the hydrogen outgassing flux follows a time power-law ∼ t −κ , for which κ depends on the concentration of hydrogen in the material and on surface desorption processes. In surface-limited regime, reaction-diffusion models of hydrogen outgassing from wall material(with hydrogen diffusion in the material bulk) are shown to be equivalent to models of outgassing from wall surfaces. Experimental results showing power-law decays of hydrogen outgassing fluxes from PFCs during long off-plasma events (κ = 0.7 for graphite and κ = 0.8 for ITER-like JET configuration) can be then reproduced using a diffusion-reaction model in surface-limited regime.

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Section: Hydrogen Desorption From Materials Surface Vs Hydrogen Desorpsupporting

confidence: 88%

“…3b and fig. 3c is due to the release of the excess of free hydrogen near the surface and has been observed experimentally in graphite [3,4]. …”

Section: Hydrogen Desorption From Materials Surface Vs Hydrogen Desorpmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

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Long‐Term Hydrogen Outgassing from Plasma Facing Components

Guterl

Smirnov

Krasheninnikov

2014

Contrib. Plasma Phys.

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“…If hydrogen outgassing is not due to purely molecular recombination, γ = 2, then the power of the flux dependence on time may also vary. The obtained time dependencies of the outgassing flux for the two surface limited regimes demonstrate that the experimentally observed long-term tails of hydrogen desorption fluxes from tokamak walls [4,5], following ∼ t −0.7±0.1 dependence, can be explained by the low energy slope of the bound hydrogen density of states function, but not by the regime of high free hydrogen densities, which would require negative values of γ. The n f n regime can also be expected for long-term outgassing, when amount of remaining hydrogen in the wall is low.…”

Section: Hydrogen Outgassingmentioning

confidence: 66%

Modeling of Hydrogen Retention and Outgassing from Co‐Deposits with Distributed Energy States

Smirnov

Krasheninnikov

Guterl

et al. 2014

Contrib. Plasma Phys.

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A hydrogen retention/outgassing model with distributed hydrogen energy states in material is proposed. The model considers hydrogen in co-deposits to occupy continuous energy states arising from all realizable local atomic arrangements in a medium with some degree of disorder. The outgassing flux of hydrogen from a sample is described via occupancy evolution of energy states corresponding to free hydrogen. We apply the model to analysis of hydrogen thermo-desorption experiments on beryllium co-deposits produced in a Be capable sputter magnetron system at the UCSD PISCES laboratory. It is demonstrated that the model can describe experimentally obtained time evolutions of hydrogen desorption flux from co-deposits in different thermal outgassing regimes.

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“…Although for safety issues carbon has been left away from promising materials for ITER, experience gained with graphitic materials for understanding processes at play in plasma/wall interactions is still useful . For example, detailed analyses of deuterium implantation and retention in the C/C composites of the Tore Supra tokamak walls have been recently performed, and have lead to a consistent understanding of the C and D balance and migration during the whole Tore Supra operation …”

Section: Introductionmentioning

confidence: 99%

In‐plane and out‐of‐plane defects of graphite bombarded by H, D and He investigated by atomic force and Raman microscopies

Pardanaud

Martin

Cartry

et al. 2014

J Raman Spectroscopy

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International audienceGraphite samples exposed to H, D and He plasma at fluencies from 10(16) to 10(18)cm(-2) have been investigated by means of atomic force and Raman microscopies. The ion energy was varied between 40 and 800eV, and the ion incidence was either perpendicular (Highly Oriented Pyrolitic Graphite) or parallel (carbon/carbon composite) to the basal plane. When increasing the impinging ion energy, the growth of nanometric domes at the surface has been observed by atomic force microscopy and the incident kinetic energy has been found as the parameter determining their height. Two different Raman signatures related to (1) a graphitic nano-crystalline component similar to that of a 10(14)cm(-2) bombarded 1-, 2- and 3-layer graphene, and to (2) an amorphous component, have been evidenced. Polarization studies have revealed that these components are related to regions with either in-plane or out-of-plane disorder, coexisting in the material. These Raman studies have also revealed that both the defect-defect distance in the first case and the aromatic domain size in the second case are typically 1nm. When the number of vacancies created in the material increases, the number of in-plane defects decreases to the benefit of the out-of-plane defects. Copyright (c) 2014 John Wiley & Sons, Ltd

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Deuterium inventory in Tore Supra: Contribution of carbon deposits outgassing

Cited by 12 publications

References 14 publications

Long‐Term Hydrogen Outgassing from Plasma Facing Components

Long‐Term Hydrogen Outgassing from Plasma Facing Components

Modeling of Hydrogen Retention and Outgassing from Co‐Deposits with Distributed Energy States

In‐plane and out‐of‐plane defects of graphite bombarded by H, D and He investigated by atomic force and Raman microscopies

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