Ablative removal of codeposits on JT-60 carbon tiles by an excimer laser

Shu, W.M.; Kawakubo, Y.; Masaki, K.; Nishi, M.

doi:10.1016/s0022-3115(02)01416-2

Cited by 23 publications

(28 citation statements)

References 10 publications

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“…Those values were smaller than that obtained from the 20 pico-sec laser irradiation by a factor of ~ 4. On the other hand, those were larger than that obtained from 25 nano-sec ArF (193 nm) laser irradiation reported by Shu et al [5] by a factor of ~ 4. It means that pulse duration can play important role from the viewpoint of removal efficiency.…”

Section: /14contrasting

confidence: 67%

“…Although this method is effective for tritium retained in the near surface, complete removal from thick codeposited layer is difficult. Another approach is the ablation-assisted removal by using high-power pulsed-laser irradiation [5][6][7][8][9][10][11][12], which is the topic of this paper. It is possible to remove not only tritium but also deposited layer itself by ablation, hence almost complete removal is expected.…”

Section: Introductionmentioning

confidence: 99%

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Removal of the deposition on JT-60 tile by nano-sec pulsed-laser irradiation

Sugiyama

Sakawa

Tanabe

et al. 2010

Journal of Nuclear Materials

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To clarify the property of tritium removal from carbon codeposition by using pulsed-laser induced desorption, hydrogen removal from co-deposits on JT-60 divertor tile using a fourth-harmonic emission (266 nm) of a nano-sec Nd:YAG laser was demonstrated. The threshold laser fluence for ablation was ~ 0.3 J/cm 2 , which was slightly higher compared to that of the pico-sec laser irradiation. The energy absorption coefficient for the nano-sec laser, which was obtained by fitting the removal rate by so-called Beer's law, was larger than the pico-sec laser. Since the time constant of thermal wave propagation into the target is of the order of nanosecond, such differences between nano-and pico-sec lasers could be attributed to thermal effects. The ablation threshold of the deposited layer was lower than that of a pure graphite, which could be attributed to the difference of thermal conductivity between deposited layer and pure graphite. The removal rate of the nano-sec laser was higher than that of pico-sec laser in the fluence range of < 0.5 J/cm 2 . On the other hand, the production ratio [hydrocarbon species] / [H 2 ] continuously increased with the laser fluence, and no significant ionization of carbon was observed in this fluence range. This indicated that the fluence range in this study was "weak"-ablation range, which was still not sufficient to minimize the hydrocarbon production.

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Section: /14contrasting

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Removal of the deposition on JT-60 tile by nano-sec pulsed-laser irradiation

Sugiyama

Sakawa

Tanabe

et al. 2010

Journal of Nuclear Materials

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“…At the IPPLM the investigation of the LIBS has been carried out together with the optimization of the laser desorption [2,3] and ablation [4][5][6][7][8][9][10] methods for the removal of the layers co-deposited on the first wall components. After obtaining promising results for removal of thick co-deposites from TEXTOR limiter [11,12], application of LIBS as real-time diagnostics for the process has been proposed and successfully tested [13].…”

Section: Introductionmentioning

confidence: 99%

Laser induced breakdown spectroscopy as diagnostics for fuel retention and removal and wall composition in fusion reactors with mixed-material components

Gąsior

Bieda

Kubkowska

et al. 2011

Fusion Engineering and Design

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In order to apply Laser Induced Breakdown Spectroscopy (LIBS) for diagnostics of fuel retention and removal and wall composition in ITER it is necessary to validate the method in terms of repeatability and quality of its results for mixed, especially ITER relevant materials and its sensitivity to thin layers which contain small amounts of retained fuel.The experiments, which are within the scope of this paper were carried out at the IPPLM Warsaw to assess the method for the laser treatment of ASDEX Upgrade (AUG) strike-point tiles and calibrated C:W:Al samples prepared by the Institute of Electronic Materials Technology (IEMT). The samples under investigation contained hydrogen isotopes in the ITER-relevant mixed material layer (as the Beryllium analogue, Al was used). Electrostatic ion energy analyzer was used as the auxiliary diagnostics.The results proved that optical spectroscopy, although not straightforward in use, can give reliable results even for small amounts of fuel present in the mixed-material layer, although more effort should be put into investigating calibrated samples, to optimize the method itself and to yield a quantitative measure of fuel retention.

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“…The complexity of this task has been understood leading to the conclusion that no single method alone -proposed until now [1] -would be fully sufficient to solve the problem. Among several techniques being developed for that purpose, photonic cleaning by laser pulses has been tested on PFC in laboratories [2][3][4][5][6][7] showing that the whole co-deposited layer could be removed [8][9][10]. The efficacy of fuel removal by flash-lamp light was tested in the JET tokamak during a shut-down period using a remote handling system [11].…”

Section: Introductionmentioning

confidence: 99%