The first results of O-ICR experiments to remove re-deposited layers and hydrogen in the HT-7 superconducting tokamak

Hu, Jiansheng; Li, J G; Wang, X M; team, the HT-7

doi:10.1088/0741-3335/47/8/009

Cited by 26 publications

(44 citation statements)

References 24 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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“…Carbon removal rates were determined by residual mass analysis of the exhaust gas and impressive cleaning rates could be extrapolated to ITER [395].…”

Section: Conditioning With Permanent Magnetic Fieldmentioning

confidence: 99%

Chapter 4: Power and particle control

Loarte¹,

et al. 2007

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Abstract.Progress, since the ITER Physics Basis publication, in understanding the processes that will determine the properties of the plasma edge and its interaction with material elements in ITER is described. Experimental areas where significant progress has taken place are : energy transport in the SOL in particular of the anomalous transport scaling, particle transport in the SOL that plays a major role in the interaction of diverted plasmas with the main chamber material elements, ELM energy deposition on material elements and the transport mechanism for the ELM energy from the main plasma to the plasma facing components, the physics of plasma detachment and neutral dynamics including the edge density profile structure and the control of plasma particle content and He removal, the erosion of low and high Z materials in fusion devices, their transport to the core plasma and their migration at the plasma edge including the formation of mixed materials, the processes determining the size and location of the retention of tritium in fusion devices and methods to remove it and the processes determining the efficiency of the various fuelling methods as well as their development towards the ITER requirements. This experimental progress has been accompanied by the development of modelling tools for the physical processes at the edge plasma and plasma-materials interaction and the further validation of these models by comparing their predictions with the new experimental results. Progress in the modelling development and validation has been mostly concentrated in the following areas : refinement of the predictions for ITER with plasma edge modelling codes by inclusion of detailed geometrical features of the divertor and the introduction of physical effects, which can play a 2 major role in determining the divertor parameters at the divertor for ITER conditions such as hydrogen radiation transport and neutral-neutral collisions, modelling of the ion orbits at the plasma edge, which can play a role in determining power deposition at the divertor target, models for plasma-materials and plasma dynamics interaction during ELMs and disruptions, models for the transport of impurities at the plasma edge to describe the core contamination by impurities and the migration of eroded materials at the edge plasma and its associated tritium retention and models for the turbulent processes that determine the anomalous transport of energy and particles across the SOL. The implications for the expected performance of the reference regimes in ITER, the operation of the ITER device and the lifetime of the plasma facing materials are discussed. Introduction.This chapter outlines the significant progress achieved since the ITER Physics Basis in understanding basic scrape-off layer (SOL) and divertor processes in a tokamak. The interaction of plasma with first-wall surfaces will have considerable impact on the performance of fusion plasmas, the lifetime of plasma facing components, and the retention of tritium in next step Burning Plasma E...

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“…Examples of applications are patterning processes in microelectronics fabrication [1][2][3], the removal of diffusionbarrier carbon coatings on polyethylene terephthalate bottles prior to recycling [4], and the cleaning of optical components in synchrotron beamlines [5]. More recently it has also attracted considerable attention for the removal of redeposited hydrocarbon films in magnetic-confinement nuclear fusion experiments [6][7][8][9][10][11][12].…”

mentioning

confidence: 99%

Chemical sputtering of carbon films by argon ions and molecular oxygen at cryogenic temperatures

Hopf

Schlüter

Jacob

2007

Applied Physics Letters

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The experiments demonstrate the existence of a synergistic interaction of molecular oxygen and energetic ions with amorphous carbon leading to enhanced erosion; although the samples, amorphous hydrogenated carbon films, are not gasified by O 2 at room temperature, additional ion bombardment at the same temperature leads to erosion rates that drastically exceed those of physical sputtering. Investigation of the temperature dependence from 400 down to 113 K shows that the erosion rate increases with decreasing temperature.

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The first results of O-ICR experiments to remove re-deposited layers and hydrogen in the HT-7 superconducting tokamak

Cited by 26 publications

References 24 publications

Erosion of tungsten-doped amorphous carbon films in oxygen plasma

Erosion of tungsten-doped amorphous carbon films in oxygen plasma

Chapter 4: Power and particle control

Chemical sputtering of carbon films by argon ions and molecular oxygen at cryogenic temperatures

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