Tritium removal from codeposits on carbon tiles by a scanning laser

Skinner, C.H.; Gentile, C.; Carpe, A.; Guttadora, G.; Langish, S.; Young, K. M.; Shu, W.M.; Nakamura, Hiroo

doi:10.1016/s0022-3115(02)00713-4

Cited by 44 publications

(6 citation statements)

References 32 publications

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“…After irradiation at high scan speeds (1,000 mm/s, surface temperature above 500 °C for 10 ms) there is a slight color change but the codeposit appears undisturbed even though the temperature reached 1,770 °C and 18 mCi of tritium was released (Fig. 4(a)) [6]. However, at slow scan speeds substantial surface damage and material loss from the surface occurs.…”

Section: Microscopy Of the Surfacementioning

confidence: 99%

“…This takes advantage of advances in laser technology to rapidly heat co-deposited layers with a high-power scanning laser beam and thermally desorb tritium. Recent experimental tests have successfully removed 84% of the codeposited tritium on TFTR tiles by this method [6]. The technique is attractive for tritium removal in a next-step DT device since it avoids the use of oxidation, the associated deconditioning of the plasma facing surfaces and expense of processing large quantities of tritium oxide [7].…”

Section: Introductionmentioning

confidence: 99%

“…The response is measured without the complications of vapor shielding, which may attenuate the thermal flux in a tokamak. The experimental setup is the same as used for the laser detritiation experiments fully reported in [6]. In the present paper we focus on the material response to the laser heat flux.…”

Section: Introductionmentioning

confidence: 99%

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High Heat Flux Interactions and Tritium Removal from Plasma Facing Components by a Scanning Laser

Skinner¹,

Gentile²,

Hassanein³

2002

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A new technique for studying high heat flux interactions with plasma facing components is presented. The beam from a continuous wave 300 W neodymium laser was focussed to 80 W/mm 2 and scanned at high speed over the surface of carbon tiles. These tiles were previously used in the TFTR inner limiter and have a surface layer of amorphous hydrogenated carbon that was codeposited during plasma operations. Laser scanning released up to 84% of the codeposited tritium. The temperature rise of the codeposit on the tiles was significantly higher than that of the manufactured material. In one experiment, the codeposit surface temperature rose to 1,770°C while for the same conditions, the manufactured surface increased to only 1,080 °C. The peak temperature did not follow the usual square-root dependence on heat pulse duration. Durations of order 100 ms resulted in brittle destruction and material loss from the surface, while a duration of ≈10 ms showed minimal change. A digital microscope imaged the codeposit before, during and after the interaction with the laser and revealed hot spots on a 100-micron scale. These results will be compared to analytic modeling and are relevant to the response of plasma facing components to disruptions and vertical displacement events (VDEs) in next-step magnetic fusion devices.

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Section: Microscopy Of the Surfacementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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High Heat Flux Interactions and Tritium Removal from Plasma Facing Components by a Scanning Laser

Skinner¹,

Gentile²,

Hassanein³

2002

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“…The focussed beam from a continuous wave 325 watt Nd:yag laser was scanned in a raster pattern over the codeposited surface transiently heating it up to 1500 -2000 C for 10 -200 ms releasing a major fraction of the tritium [ 23]. The surface temperature was measured by a pyrometer operating in the 1.58 -1.8 micron band, with a 0.7 mm measuring spot and response time of 0.3 ms. Interestingly the temperature excursion of the codeposited layer was significantly higher than a bare graphite surface (1770 C compared to 1080 C), implying a very different thermal con- ductivity.…”

Section: Tritium Removal By a Scanning Lasermentioning

confidence: 99%

Tritium Issues in Next Step Devices

Skinner

Federici

2002

Advanced Diagnostics for Magnetic and Inertial Fusion

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“…The tiles were scanned with a laser to heat the surface and release the tritium from the codeposited layers [94][95]. Initial results look promising and the possibility of using this technique on future JET experiments is being discussed.…”

Section: Technology Associated With Deuterium-tritium Experimentsmentioning

confidence: 99%

Review of D-T Experiments Relevant to Burning Plasma Issues

Hawryluk¹

2001

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Progress in the performance of tokamak devices has enabled not only the production of significant bursts of fusion energy from deuterium-tritium (D-T) plasmas in the Tokamak Fusion Test Reactor (TFTR) and the Joint European Torus (JET) but, more importantly, the initial study of the physics of burning magnetically confined plasmas. TFTR and JET, in conjunction with the worldwide fusion effort, have studied a broad range of topics including magnetohydrodynamic stability, transport, wave-particle interactions, the confinement of energetic particles, and plasma boundary interactions. D-T experiments differ in three principal ways from previous experiments: isotope effects associated with the use of deuterium-tritium fuel, the presence of fusion-generated alpha particles, and technology issues associated with tritium handling and increased activation. The effect of deuteriumtritium fuel and the presence of alpha particles is reviewed and placed in the perspective of the much larger worldwide database using deuterium fuel and theoretical understanding.Both devices have contributed substantially to addressing the scientific and technical issues associated with burning plasmas. However, future burning plasma experiments will operate with larger ratios of alpha heating power to auxiliary power and will be able to access additional alpha-particle physics issues. The scientific opportunities for extending our understanding of burning plasmas beyond that provided by current experiments is described.

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Tritium removal from codeposits on carbon tiles by a scanning laser

Cited by 44 publications

References 32 publications

High Heat Flux Interactions and Tritium Removal from Plasma Facing Components by a Scanning Laser

High Heat Flux Interactions and Tritium Removal from Plasma Facing Components by a Scanning Laser

Tritium Issues in Next Step Devices

Review of D-T Experiments Relevant to Burning Plasma Issues

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