Surface temperature measurements of carbon materials in fusion devices

Hildebrandt, D.; Naujoks, D.; Sünder, D.

doi:10.1016/j.jnucmat.2004.09.033

Cited by 11 publications

(17 citation statements)

References 7 publications

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“…Fine grain graphite (FGG) is commonly used in quasi stationary machines and carbon fibre composite (CFC) is needed for actively cooled structures due to the higher mechanical strength. This behaviour was found for virgin carbon [7,8] as well as plasma exposed samples [9][10][11] in lab experiments and by plasma heating. A typical temperature response on a nearly square like heat pulse is shown in Fig.…”

Section: Graphite Without Plasma Exposuresupporting

confidence: 53%

“…Because the temperature jump is found not only for targets with plasma wall contact but also for virgin targets, it is supposed that this jump is due to grains with a reduced contact to the bulk. Carefully polishing can remove the loosely connected grains resulting in an ideal temperature behaviour of FGG [8]. The heat flux to the target can be .…”

Section: Graphite Without Plasma Exposurementioning

confidence: 99%

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Surface temperature measurement and heat load estimation for carbon targets with plasma contact and machine protection

Herrmann

2007

Phys. Scr.

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Surface temperature control of actively cooled targets is a part of the machine protection in long pulse experiments. The protection of the target is as good as the surface measurement and the thermal model of the target. This paper deduces thermal parameters necessary to correct the measured temperature by surface effects.The temperature measurement error due to the intrinsic CFC structure is discussed. Layers on top of the bulk material result in a change of the temperature response and in an overestimation of the calculated heat flux. All discussed effects did not reduce the machine safety but can reduce the operational space of the experiment. The thermal surface properties have to be checked in-situ by changing the heat load to the target and calculating the temperature response.

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Section: Graphite Without Plasma Exposuresupporting

confidence: 53%

Section: Graphite Without Plasma Exposurementioning

confidence: 99%

Surface temperature measurement and heat load estimation for carbon targets with plasma contact and machine protection

Herrmann

2007

Phys. Scr.

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“…Their surface morphology is characterized by a mean surface roughness of 15 µm [4]. The thermal conductivity of the CFC material at room temperature has been determined for all three directions in separate heat pulse experiments [3].…”

Section: Methodsmentioning

confidence: 99%

“…In order to investigate thermal conditioning effects [4] we started the experiments with a low power density pulse of 4 MW/m 2 and 1 sec duration. For two successive pulses the power density and pulse duration was increased to 10.5 MW/m 2 and 5 sec, respectively.…”

Section: Methodsmentioning

confidence: 99%

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Thermal response to heat fluxes of the W7-AS divertor surface submitted to surface modification under high temperature treatment

Hildebrandt¹,

Dübner²,

Greuner³

et al. 2009

Journal of Nuclear Materials

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Some target tiles of the W7-AS divertor has been investigated with respect to their thermal behaviour at the surface during power loading with well defined heat fluxes in the Gladis facility. The primary aim was to examine uncertainties in the determination of heat fluxes derived from IR-thermography during operation of W7-AS. It is found that the derived heat flux profiles are strongly influenced by the local distribution of plasma-deposited contamination analyzed by AES and SIMS. With the observed actual surface conditions characterized by redeposited contamination equivalent up to about 1 µm thickness, the heat fluxes were partially overestimated up to a factor of 4 during operation of W7-AS. This uncertainty is observed to be significantly reduced after heat treatment at temperatures beyond 700 o C attained at power flux densities of 10.5 MW/ m 2 and durations longer than 5 seconds.

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Thermal response of structured and contaminated carbon surfaces to heat pulses

Hildebrandt

Duebner

2007

Journal of Nuclear Materials

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Experiments involving well-defined heat pulses of laser radiation on the CFC target material NB31 and plasma-exposed CFC-samples with known composition and thickness of the contamination layer have been performed to investigate the thermal properties and behaviour at the surface. Special attention is focussed on the dependence of the surface temperature enhancement and its temporal evolution on the amount of the deposited material. The measured surface temperature excursions are compared with values of analytical and numerical solutions of the heat diffusion equation taking into account a surface region with low thermal conductivity or poor thermal contact to the underlying substrate material.

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Surface temperature measurements of carbon materials in fusion devices

Cited by 11 publications

References 7 publications

Surface temperature measurement and heat load estimation for carbon targets with plasma contact and machine protection

Surface temperature measurement and heat load estimation for carbon targets with plasma contact and machine protection

Thermal response to heat fluxes of the W7-AS divertor surface submitted to surface modification under high temperature treatment

Thermal response of structured and contaminated carbon surfaces to heat pulses

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