Examination of codeposited a-C:D-layers in oxygen

Moormann, R.; Alberici, S.; Hinssen, H.-K.; Wu, C.H.

doi:10.1016/s0920-3796(00)00387-2

Cited by 12 publications

(8 citation statements)

References 10 publications

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“…However, the technique has serious drawbacks, such as the required wall temperatures difficult to achieve in ITER, which should be above 550 K, the interaction with other non-carbon invessel components (such as Be), the recovery time for normal plasma operation and the processing of the resulting tritiated water. Recently, ozone has been shown to oxidise carbon layers at significantly lower temperature compared with molecular oxygen [458], but this method has not been yet demonstrated in the tokamak. More experiments are necessary to demonstrate the effectiveness of these techniques, the recovery of released tritium, the interaction with the non-carbon ITER wall materials, the handling of the debris that is potentially produced by ablative methods and the recovery of plasma operation, before a credible tritium clean up schedule and their consequences for ITER operation can be evaluated in a quantitative way.…”

Section: Tritium Removal Methodsmentioning

confidence: 99%

Chapter 4: Power and particle control

Divertor¹,

Database²,

Editors³

1999

Nucl. Fusion

280

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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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Section: Tritium Removal Methodsmentioning

confidence: 99%

Chapter 4: Power and particle control

Divertor¹,

Database²,

Editors³

1999

Nucl. Fusion

280

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“…On those areas, external heating by lamps or lasers might also be possible. These techniques cannot be used on remote areas for which no clear scenario presently exists except mechanical tools or the use of gaseous, chemical treatments by active oxygen or ozone [48,49]. These techniques must be compatible with plasma operation and need research in present tokamaks.…”

Section: Other Key Pwi Questions For Itermentioning

confidence: 99%

Key issues in plasma–wall interactions for ITER: a European approach

Philipps

Roth

Loarte

2003

Plasma Phys. Control. Fusion

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The first burning fusion plasma experiment based on the tokamak principle, international tokamak experimental reactor (ITER) is now ready for construction. Based on the continuous progress of many years of fusion research, the design relies upon a large and robust set of experimental data. The focus of present day fusion research is therefore shifting towards the issues of ITER plasma operation and machine availability. The latter is governed mainly by plasma-wall interaction issues, in particular the lifetime of plasmafacing components and long-term tritium retention. To coordinate the research activities in this area a task force for plasma-wall interaction (EU-PWI-TF) has been initiated by the European fusion research programme under EFDA. This contribution describes the experimental database in these areas and outlines the task force strategy and further research that will be needed to address the critical issues.

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“…For amorphous hydrocarbon films (a-C:H), combustion starts above 500-600 K [14,15]. The thermal oxygen radicals, atomic oxygen [16] and ozone [17], exhibit much higher reactivity at moderate temperatures, and there is indication that their reactivity toward a-C:H is still significant at room temperature. Bombardment of carbon with an oxygen ion beam leads to what is known as chemical sputtering or reactive ion etching [18][19][20]; in addition to physical sputtering the ions react chemically at the end of their range and form CO, CO 2 , and H 2 O, leading to highly enhanced sputtering yields and significantly lower threshold energies.…”

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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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Examination of codeposited a-C:D-layers in oxygen

Cited by 12 publications

References 10 publications

Chapter 4: Power and particle control

Chapter 4: Power and particle control

Key issues in plasma–wall interactions for ITER: a European approach

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

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