Use of tungsten material for the ITER divertor

Hirai, T.; Panayotis, S.; Barabash, V.; Amzallag, C.; Escourbiac, F.; Durocher, A.; Merola, M.; Linke, J.; Loewenhoff, Thorsten; Pintsuk, G.; Wirtz, M.; Uytdenhouwen, I.

doi:10.1016/j.nme.2016.07.003

Cited by 254 publications

(123 citation statements)

References 26 publications

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“…Young's modulus E, Poisson's ratio ν and shear modulus G) and the coefficient of thermal expansion α of the coatings were determined by the combined use of Brillouin spectroscopy and the substrate curvature method in previous works [40,41]. They are summarized in table 1. No information about the elastic properties of the a-WO 3 sample is available yet.…”

Section: Sample Pre-and Post-irradiation Characterizationmentioning

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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Section: Sample Pre-and Post-irradiation Characterizationmentioning

confidence: 99%

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

et al. 2018

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“…During the operation of ITER, high-temperature plasma will deposit energy on the surface of divertor target through thermal radiation and particle collision. During some transient event (up to 10 s), steady load can reach to 10~20 MW/m 2 at tungsten monoblock in the vertical target 9 . To study the real working conditions of the monoblock in the fusion device, heat flux loads which range from 6 MW/m 2 to 20 MW/m 2 were applied on the top surface of tungsten monoblock.…”

Section: Steady Heat Flux Simulationmentioning

confidence: 99%

“…In addition, tungsten monoblocks in the divertor vertical target are designed as the high heat flux handling unit where heat loads are maximal 9 . Therefore, the study on the thermal shock performance and damage behavior of tungsten divertor monoblock is of great significance to the safe operation of the reactor.…”

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confidence: 99%

Thermal damage of tungsten-armored plasma-facing components under high heat flux loads

Wang

et al. 2020

Sci Rep

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Fusion energy is expected as a promising candidate for alternative next generation energy. For fusion reactor, the plasma facing components (PFCs) are the most critical components to achieve this goal. PFCs will suffer severe thermal shock due to repective cyclic high heat flux (HHF) loads. This paper investigates the effects of thermal shock and damage behavior of tungsten armored PFCs under steady, transient and combined thermal loads. The distribution of stress field is analyzed, and crack initiation is predicted using the extended finite element method (XFEM). The unique features of thermalmechanical behavior of tungsten armored PFCs under simulated service condition are discussed. The dominant factor of the cracking of the tungsten armor is the brittleness of tungsten below ductileto-brittle transition temperature (DBTT). Under the steady loads, the cracking position is apt to near the interface of tungsten armor and the interlayer, and the threshold of cracking is between 14 MW/ m 2 and 16 MW/m 2 . With 6 MW/m 2 steady loads, applying 1 ms duration of transient load, the cracking threshold is between 0.2 GW/m 2 to 0.4 GW/m 2 . The depth of cracking increases from 100 um to 500 um with the transient load increasing from 0.4 GW/m 2 to 1.0 GW/m 2 . Researches are useful for the design and structural optimization of tungsten-armored PFCs, and the long-term stable operation of further reactor. FE ModelGeometry, FE mesh and materials. We design the monoblock and build the model as shown in Fig. 1 8,10-12 .Both width and height of the selected monoblock are 28 mm, the axial length is 12 mm and the armor thickness is 6 mm. The CuCrZr alloy has been chosen as the heat sink material because of its good irradiation resistance and high thermal conductivity, and its tube diameters are 12/15 mm (ID/OD). The oxygen free high conductivity copper (OFHC-Cu)

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“…Taking ξ = 2-3, T = 300 • C for the vessel wall [37], and T = 1100 • C for the divertor [38] would suggest P abs = 0.4-0.6% for the ITER Be walls, 0.6-0.9% for the W divertor, and 1.0-1.5% for any stainless-steel surfaces at f = 60 GHz, with a frequency dependence that can be ignored here. Hence, for plain surfaces, the typical wall reflectivity will not exceed R w = 1 − P abs ≈ 0.995, and this is made more relevant still by the consideration that the adopted value represents an average over all incidence angles (see below).…”

Section: Wall Reflectivitymentioning

confidence: 99%

Modeling the electron cyclotron emission below the fundamental resonance in ITER

Rasmussen

Stejner

Figini

et al. 2019

Plasma Phys. Control. Fusion

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The electron cyclotron emission (ECE) in fusion devices is nontrivial to model in detail at frequencies well below the fundamental resonance where the plasma is optically thin. However, doing so is important for evaluating the background for microwave diagnostics operating in this frequency range.Here we present a general framework for estimating the ECE levels of fusion plasmas at such frequencies using ensemble-averaging of rays traced through many randomized wall reflections. This enables us to account for the overall vacuum vessel geometry, self-consistently include cross-polarization, and quantify the statistical uncertainty on the resulting ECE spectra. Applying this to ITER conditions, we find simulated ECE levels that increase strongly with frequency and plasma temperature in the considered range of 55-75 GHz. At frequencies smaller than 70 GHz, we predict an X-mode ECE level below 100 eV in the ITER baseline plasma scenario, but with corresponding intensities reaching keV levels in the hotter hybrid plasma scenario. Benchmarking against the SPECE raytracing code reveals good agreement under relevant conditions, and the predicted strength of Xmode to O-mode conversion induced by wall reflections is consistent with estimates from existing fusion devices. We discuss possible implications of our findings for ITER microwave diagnostics such as ECE, reflectometry, and collective Thomson scattering.

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Use of tungsten material for the ITER divertor

Cited by 254 publications

References 26 publications

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

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

Thermal damage of tungsten-armored plasma-facing components under high heat flux loads

Modeling the electron cyclotron emission below the fundamental resonance in ITER

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