Plasma-assisted laser ablation of tungsten: Reduction in ablation power threshold due to bursting of holes/bubbles

Kajita, Shin; Ohno, Noriyasu; Takamura, S.; Sakaguchi, Wataru; Nishijima, D.

doi:10.1063/1.2824873

Cited by 41 publications

(27 citation statements)

References 9 publications

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“…Recently, Takamura et al [3] found for the first time that deeply nanostructured tungsten (or ''fuzz'') with an arborescent shape was formed on tungsten-coated graphite via high-flux He plasma irradiation. This structure was demonstrated to greatly change the physical properties of the W surface such as the heat transfer, fuel (deuterium/tritium) retention and erosion rates, which severely impact the operation of fusion devices [4][5][6][7][8]; therefore, it is very important to understand the formation mechanism of fuzz on the surface. To date, various mechanisms have been advocated to explain the formation of such nanostructures experimentally and theoretically.…”

Section: Introductionmentioning

confidence: 99%

New interatomic potentials for studying the behavior of noble gas atoms in tungsten

Zhou

Fang

Deng

et al. 2015

Journal of Nuclear Materials

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Section: Introductionmentioning

confidence: 99%

New interatomic potentials for studying the behavior of noble gas atoms in tungsten

Zhou

Fang

Deng

et al. 2015

Journal of Nuclear Materials

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“…In addition, they have also been applied to the investigation of ablation and melting thresholds on different plasma-exposed W materials, in order to highlight the role of He bubbles on the behavior of W under extreme thermal loads [30,31]. Recently, thermal effects induced on W by ITER-relevant thermal loads have also been mimicked by nanosecond lasers [32].…”

Section: Introductionmentioning

confidence: 99%

Nanosecond laser pulses for mimicking thermal effects on nanostructured tungsten-based materials

et al. 2018

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In this work, we exploit nanosecond laser irradiation as a compact solution for investigating the thermomechanical behavior of tungsten materials under extreme thermal loads at the laboratory scale. Heat flux factor thresholds for various thermal effects, such as melting, cracking and recrystallization, are determined under both single and multishot experiments. The use of nanosecond lasers for mimicking thermal effects induced on W by fusionrelevant thermal loads is thus validated by direct comparison of the thresholds obtained in this work and the ones reported in the literature for electron beams and millisecond laser irradiation. Numerical simulations of temperature and thermal stress performed on a 2D thermomechanical code are used to predict the heat flux factor thresholds of the different thermal effects. We also investigate the thermal effect thresholds of various nanostructured W coatings. These coatings are produced by pulsed laser deposition, mimicking W coatings in tokamaks and W redeposited layers. All the coatings show lower damage thresholds with respect to bulk W. In general, thresholds decrease as the porosity degree of the materials increases. We thus propose a model to predict these thresholds for coatings with various morphologies, simply based on their porosity degree, which can be directly estimated by measuring the variation of the coating mass density with respect to that of the bulk.

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“…Up to now, the heat load on the divertor in previous MCF systems has been unreached parameter. Thus, to predict properties of the divertor under these heat loads, several experiments have been performed using electron [5] or plasma guns [6,7], or intense laser intended to reproduce relevant heat fluxes [8]. These experiments have mainly been employed to evaluate metallurgical characteristics of the tungsten divertor.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Transport Properties in Warm Dense Matter Generated by Pulsed-power Discharge for Nuclear Fusion Systems

et al. 2015

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To achieve the thermonuclear fusion systems, the physical properties of warm dense matter (WDM) are key parameters. In this paper, we review the evaluation of physical properties in WDM by using pulsed-power discharges. To evaluate the thermal conductivity for a divertor wall in magnetic confinement fusion, we investigate a semi-empirical evaluation based on the experimental values for electrical resistivity. The results indicate that, in the region between the intermediate degeneracy and the non-degeneracy, the evaluated thermal conductivity has an inflection point. To evaluate the electrical resistivity for the fuel target in the inertial confinement fusion, an isochoric heating by using pulsed-power discharge in the pressure vessel has been demonstrated. The results indicate that the electrical resistivity in WDM for gold is 100 μΩ · m at 0.1ρ s (ρ s : solid density) of density and the internal energy is 1 MJ/kg.

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Plasma-assisted laser ablation of tungsten: Reduction in ablation power threshold due to bursting of holes/bubbles

Cited by 41 publications

References 9 publications

New interatomic potentials for studying the behavior of noble gas atoms in tungsten

New interatomic potentials for studying the behavior of noble gas atoms in tungsten

Nanosecond laser pulses for mimicking thermal effects on nanostructured tungsten-based materials

Evaluation of Transport Properties in Warm Dense Matter Generated by Pulsed-power Discharge for Nuclear Fusion Systems

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