Oxidation for deposits removal and hydrogen release on HT-7

Hu, Jiansheng; Li, J.G.; Wang, X.M.; Zhao, Yan

doi:10.1016/j.jnucmat.2007.01.286

Cited by 17 publications

(15 citation statements)

References 22 publications

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“…Among these techniques, oxygen glow discharge cleaning was proven as one promising candidate to remove re-deposited layers. For example, ASDEX Upgrade showed that removal is very effective even at room temperature and similar results were obtained in TEXTOR and HT-7 for elevated temperatures [4][5][6][7][8]. Schwarz-Selinger et al [11,12] have recently shown that oxygen plasmas are very efficient for removal of hydrocarbon films which are a good model system for re-deposited carbon films in fusion devices.…”

Section: Introductionmentioning

confidence: 69%

“…To avoid continuous build-up of a fuel inventory inside the vacuum vessel, a variety of techniques for regular tritium removal have been proposed. These techniques include glow discharge cleaning [4][5][6][7][8], thermal oxidation [9] and laser and flash lamp ablation techniques [10]. Among these techniques, oxygen glow discharge cleaning was proven as one promising candidate to remove re-deposited layers.…”

Section: Introductionmentioning

confidence: 99%

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Erosion of tungsten-doped amorphous carbon films in oxygen plasma

Wang

Jacob

Balden

et al. 2012

Journal of Nuclear Materials

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Abstract:Tungsten-doped amorphous carbon films with 0-9 at.% W concentration were produced by magnetron sputtering and eroded in oxygen plasmas applying different bias voltages and substrate temperatures. The partial C and W erosion rates were determined from the C and W areal density changes measured by Rutherford backscattering spectrometry (RBS). The initial C removal rate increases with increasing ion energy and temperature and decreases with increasing W concentration. For W-doped films the erosion rate decreases with increasing plasma exposure duration. At low bias voltages the erosion process stops after W accumulation at the surface, which protects the carbon underneath from further erosion. RBS and X-ray photoelectron spectroscopy suggest that the Wrich layer at the surface is carbon free and consists of porous WO 3 . Biasing to 200 V leads to removal of W by physical sputtering and, therefore, inhibits the formation of the protecting W oxide layer and the C erosion proceeds.

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Section: Introductionmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Erosion of tungsten-doped amorphous carbon films in oxygen plasma

Wang

Jacob

Balden

et al. 2012

Journal of Nuclear Materials

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“…A second TGTS was exposed to the remote ECR discharge at elevated temperature (470 K). Apart from the temperature and the exposure time the experimental parameters were identical to the previous experiment (figure 7). Figure 8 shows the eroded film thickness at the side wall TGTS substrates in logarithmic scale for the four different gaps for this case.…”

Section: Erosion In Tile Gapsmentioning

confidence: 96%

“…mechanical removal and laser desorption and ablation techniques, oxygen glow discharge cleaning was proposed as one possible candidate to remove redeposited hydrocarbon films [1]. For removal of redeposited films from plasma-wetted areas and other locations that are accessible by remote handling, all these methods seem to be promising [4][5][6][7][8][9][10]. Especially for plasma oxidation, e.g.…”

Section: Introductionmentioning

confidence: 99%

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Fuel removal from tile gaps with oxygen discharges: reactivity of neutrals

et al. 2009

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Carbon removal in so-called remote areas, where no energetic species can reach the surface, is investigated with low-temperature glow discharges in pure oxygen. Plasma-deposited amorphous hydrogenated carbon thin films are used as a model system for redeposited films. Erosion measurements are performed on flat substrates as well as on two different 3D test structures. One design consists of 19 mm deep gaps with widths ranging from 0.5 to 4 mm to simulate ITER tile gaps. A second design consists of a flat box-like structure where particles can enter only through a narrow slit. Measurements are performed for substrate temperatures ranging from 290 to 580 K. Erosion rates follow an Arrhenius-type dependence on substrate temperature with an effective activation energy of 0.25 eV. While at room temperature the surface loss probability of the dominant eroding species is 50 % it becomes smaller at elevated temperatures. At elevated temperatures the films are not only removed faster but simultaneously erosion penetrates deeper into the gaps.

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Treatment of ITER plasma facing components: Current status and remaining open issues before ITER implementation

Grisolia¹,

Counsell²,

Dinescu³

et al. 2007

Fusion Engineering and Design

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The in-vessel tritium inventory control is one of the most ITER challenging issues which has to be resolved to fulfil safety requirements. This is due mainly to the presence of carbon as a constituent of plasma facing components (PFCs) which leads to a high fuel permanent retention. For several years now, physics studies and technological developments have been undertaken worldwide in order to develop reliable techniques which could be used in ITER severe environment (magnetic field, vacuum, high temperature) for in situ tritium recovery. The scope of this contribution is to review the present status of these achievements and define the remaining work to be done in order to propose a dedicated work program.Different treatment techniques (chemical treatments, photonic cleaning) will be reviewed. In the frame of ITER, they will be compared in terms of fuel removal rate as well as surface accessibility, type of production (gas or particulates), ability to clean mixed material.And lastly, consequences of bulk trapping observed in tokamak on the techniques currently under development will be addressed.Published with Fusion Engineering and Design: Fus. Eng. Des. 82 (2007Des. 82 ( ) 2390Des. 82 ( -2398

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Oxidation for deposits removal and hydrogen release on HT-7

Cited by 17 publications

References 22 publications

Erosion of tungsten-doped amorphous carbon films in oxygen plasma

Erosion of tungsten-doped amorphous carbon films in oxygen plasma

Fuel removal from tile gaps with oxygen discharges: reactivity of neutrals

Treatment of ITER plasma facing components: Current status and remaining open issues before ITER implementation

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