Gas-driven hydrogen permeation through tungsten-coated graphite

Голубева, А. В.; Спицын, А. В.; Mayer, M.; Черкез, Д. И.; Schwarz-Selinger, T.; Koch, F.; Lindig, S.; Skovoroda, A. A.

doi:10.1016/j.jnucmat.2011.01.106

Cited by 6 publications

(4 citation statements)

References 12 publications

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“…As it has been mentioned before, the typical VPS-W coating consists of partially melted W particles, melted W and substantial surface-connected porosity [8]. Even a 200 µm thick layer of VPS-W has an open system of connected pores, which connects the front and rear surfaces of the deposited layer [6]. The density of the prepared VPS-W coating is ∼90% of bulk W, which means the porosity is ∼10%, including open (or connected) pores and closed pores.…”

Section: Resultsmentioning

confidence: 93%

“…Vacuum plasma spraying is an efficient technique to get W coatings. As it has been investigated by Golubeva et al [6], that the mechanism of hydrogen permeation through VPS-W coated graphite is molecular hydrogen gas author's e-mail: xu.yue@LHD.nifs.ac.jp * ) This article is based on the presentation at the 25th International Toki Conference (ITC25). flow through the system of connected porosity.…”

Section: Introductionmentioning

confidence: 99%

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Hydrogen Gas-Driven Permeation through F82H Steel Coated with Vacuum Plasma-Sprayed Tungsten

Hirooka

Nagasaka

et al. 2016

Plasma and Fusion Research

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The subject of hydrogen isotopes transport through tungsten coated reduced activation ferritic steels such as F82H has attracted increasing interest in the fusion engineering research community. This paper reports on laboratory-scale studies that have been done to assess the hydrogen permeation properties of vacuum plasmasprayed tungsten (VPS-W) coatings at the temperature range of 200-500 • C. W coatings with thicknesses of 46 µm and 90 µm have been investigated. It has been found that the observed permeation rates through composite VPS-W/F82H specimen are reduced to ∼7% compared to that of pure F82 H. VPS-W coating is porous and has an open system of connected pores, which density is evaluated to be ∼7%. The main effect of the W coating on hydrogen permeation is to reduce the incoming flux at the W/F82H interface owing to pore diffusion in the coating and to reduce the effective surface area for hydrogen dissolution in the substrate.

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Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Hydrogen Gas-Driven Permeation through F82H Steel Coated with Vacuum Plasma-Sprayed Tungsten

Hirooka

Nagasaka

et al. 2016

Plasma and Fusion Research

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“…The readers are referred to reports by Anderl [5], Otsuka [6] and Golubeva [7] for the permeation properties of hydrogen through VPS-W. Reduced permeation fluxes are attributed to the complex microstructure and a substantial surface-connected porosity.…”

Section: Hydrogen Isotopes Plasma-driven Permeation Through Tungsten mentioning

confidence: 99%

Hydrogen Isotopes Plasma-Driven Permeation through Tungsten Coated Reduced Activation Ferritic Steel F82H

Hirooka

Nagasaka

et al. 2017

Plasma and Fusion Research

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Hydrogen isotopes plasma-driven permeation (PDP) through F82H coated with two different types of tungsten coatings, i.e., sputter-deposited tungsten (SP-W) and vacuum plasma-sprayed tungsten (VPS-W) has been studied in the temperature range of 300 -550• C. It has been found that hydrogen isotopes PDP fluxes through VPS-W coated F82H are reduced compared to that through bare F82H. However, the PDP fluxes through SP-W coated F82H are enhanced compared to bare F82H. Reduced or enhanced PDP fluxes are related to the different microstructure of tungsten coatings and its surface recombination characteristics. Tungsten (W) has been proposed as a candidate plasma-facing material for ITER divertor because of its beneficial properties such as high melting point, high thermal conductivity and low sputtering yield [1]. For a DEMO reactor, surface coatings made of W are necessary to protect the plasma-facing wall made of reduced activation ferritic steels such as F82H [2]. The characterization of hydrogen isotopes transport through W coated F82H is of crucial importance to evaluate major reactor design issues including tritium retention, breeding feasibility and first wall particle recycling. In this work, hydrogen isotopes PDP through F82H coated with two different types of W coatings are investigated and the effects of W coatings on hydrogen PDP are discussed. Such information has important implications for the use of W coatings as plasma-facing material.Hydrogen isotopes PDP experiments are performed using a linear plasma device VEHICLE-1 [3]. The plasma density is ∼10 10 cm −3 and the electron temperature is ∼5.5 eV. The incident ion energy is controlled by biasing the sample. A bias of 100 V has been used for PDP in the present work. Taking into account the ion species mix (H + : H + 2 : H + 3 ) and surface particle reflection, the net implantation flux is estimated to be ∼1 × 10 16 H/cm 2 /s. SP-W and VPS-W coated F82H membranes are used as samples. The permeation area is 35 mm in diameter. The thickness of F82H subtract is 0.5 mm, and the thicknesses of SP-W and VPS-W coatings are 0.5 µm and 90 µm, respectively. A 0.5 mm thick bare F82H is used for comparison. Small samples with a size of 12 × 12 × 1 mm are also prepared for ex-situ analyses such as scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and

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“…tungsten with a permeability three orders of magnitude below ferritic steel, promise very small deactivation lengths [39]. Studies of physical vapor deposited (PVD) tungsten showed however that thin coatings of 2 lm do not influence significantly the permeability of sample due to remaining open pores while vacuum plasma sprayed (VPS) 200 lm films reduced hydrogen permeation remarkably [40]. Another possible option to counter the hydrogen problem is increasing permeability in cooling region, in order to promote diffusion to the ambient [41].…”

Section: Long-term Operation and Hydrogen Diffusionmentioning

confidence: 99%

Planar High Temperature Heat Pipes for SOFC/SOEC Stack Applications

2014

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Targeting transient operation of high temperature solid oxide cell (SOC) systems this paper proposes an enhanced heat management mechanism using planar high temperature heat pipes that can be integrated into the SOC‐stack structure. Flat heat pipes with thicknesses down to 4 mm filled with liquid alkali metals for almost isothermal 2D heat spreading, even for intense heat transfer rates, are demonstrated. A new pathway towards a temperature gradient shrinking in SOC‐stacks without using large amounts of additional air‐cooling is shown. The paper will present latest development results on design concepts, size reduced fabrication and filling procedure. An experimental study demonstrates the heat spreading capabilities and power limitations of planar heat spreaders for high temperature applications as in SOEC/SOFC stacks.

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Gas-driven hydrogen permeation through tungsten-coated graphite

Cited by 6 publications

References 12 publications

Hydrogen Gas-Driven Permeation through F82H Steel Coated with Vacuum Plasma-Sprayed Tungsten

Hydrogen Gas-Driven Permeation through F82H Steel Coated with Vacuum Plasma-Sprayed Tungsten

Hydrogen Isotopes Plasma-Driven Permeation through Tungsten Coated Reduced Activation Ferritic Steel F82H

Planar High Temperature Heat Pipes for SOFC/SOEC Stack Applications

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