Thermal Shock Behavior Analysis of Tungsten-Armored Plasma-Facing Components for Future Fusion Reactor

Wang, Shuming; Li, Jiangshan; Wang, Yanxin; Zhang, Xiaofang; Ye, Qing

doi:10.1007/s40195-018-0721-9

Cited by 7 publications

(6 citation statements)

References 29 publications

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“…Assuming W is an ideal elastic-plastic material, its thermal property parameters are listed in Table 1, referring to the ITER materials handbook [24] and relevant literature [25].…”

Section: Boundary Conditions and Thermal Property Parametersmentioning

confidence: 99%

Finite Element Analysis and Experimental Verification of Thermal Fatigue of W-PFM with Stacked Structure

Qi,

Song

et al. 2024

Metals

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As the prime candidate for plasma-facing materials (PFM), the response of tungsten (W) to thermal shock loads is an important research topic for future fusion devices. Under heat loads, the surface of tungsten plasma-facing materials (W-PFM) can experience thermal damage, including brittle cracking and fatigue cracks. Therefore, exploring solutions for thermal damage of W-PFM remains one of the current research focuses. We propose a novel approach to mitigate thermal radiation damage in PFM, namely, the stacked structure W-PFM. The surface thermal stress distribution of the stacked structure W-PFM under heat loads was simulated and analyzed by the finite element method. As the foil thickness decreases, both the peak thermal stresses in the normal direction (ND) and rolling direction (RD) decrease. When the thickness decreases to a certain value, the peak thermal stress in the RD decreases to about 1384 MPa and no longer decreases; while the peak thermal stress in the ND approaches 0 MPa and can be neglected. In the range of approximately 5–100 mm, the accumulated equivalent plastic strain decreases sharply as the thickness decreases; in other thickness ranges, it decreases slowly. Thermal fatigue experiments were conducted on the stacked structure W composed of W foils with different thicknesses and bulk W using an electron beam facility. The samples were applied with a power density of 30 MW/m2 for 10,000 and 20,000 pulses. The cracks on the surface of the stacked structure W extended along the ND direction, while on the surface of bulk W, besides the main crack in the ND direction, a crack network also formed. The experimental results were consistent with finite element simulations. When the pulse number was 10,000, as the thickness of the W foil decreased, the number and width of the cracks on the surface of the stacked structure W decreased. Only four small cracks were present on the surface of stacked structure W (0.05 mm). When the pulse number increased to 20,000, the plastic deformation and number of cracks on the surface of all samples increased. However, the stacked structure W (0.05 mm) only added one small crack and had the smallest surface roughness (Ra = 1.536 μm). Quantitative analysis of the fatigue cracks showed that the stacked structure W-PFM (0.05 mm) exhibited superior thermal fatigue performance.

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“…Assuming W is an ideal elastic-plastic material, its thermal property parameters are listed in Table 1, referring to the ITER materials handbook [24] and relevant literature [25].…”

Section: Boundary Conditions and Thermal Property Parametersmentioning

confidence: 99%

Finite Element Analysis and Experimental Verification of Thermal Fatigue of W-PFM with Stacked Structure

Qi,

Song

et al. 2024

Metals

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“…A square target with a cross-sectional area of 40 mm × 40 mm and a thickness of 10 mm is considered for the calculations. The reason for choosing this thickness is that for a tokamak like ITER, the thickness of the tungsten wall in the divertor area is 13 mm and in the armor section of the plasma facing components is 6 mm 32 – 34 . This value is in the range of selected thicknesses for tungsten in large size tokamaks.…”

Section: Configuration and Analysis Proceduresmentioning

confidence: 99%

Runaway electrons and their interaction with tungsten wall: a comprehensive study of effects

Ataeiseresht,

Abdi,

Pourshahab

et al. 2023

Sci Rep

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Runaway electrons are a notable phenomenon occurring during the operation of a tokamak. Proper material selection for the tokamak's first wall structure and plasma facing components, particularly in large sizes tokamaks like ITER and DEMO, is crucial due to the energy deposition of runaway electrons on plasma facing components during collision events, resulting in severe heat transfer and material damage in the form of melting, corrosion, and fracture. These runaway electrons also contribute to the production of photoneutrons through (γ, n) nuclear reactions, lead to material activation and require remote handling. In this study, using a Monte Carlo code and simulating the collision of runaway electrons with a tungsten target exposed to their radiation, the electron transport is investigated, and the energy deposition spectrum resulting from these collisions on the target is analyzed. The influence of incident angle and magnetic field on the energy deposition spectrum and the energy deposition per particle in the target is examined. With an increase in the incident angle of incoming electrons, the amount of energy deposited in the target rises and the energy deposition spectrum broadens. Moreover, applying a magnetic field, results the most significant increase in energy deposition for electrons with energies below 1 MeV in the tangential radiation case. The energy deposition spectrum resulting from each collision event in these interactions is determined. For electrons with energies below 5 MeV, multiple scattering and ionization processes are the primary contributors to energy deposition in the target. However, as the incident electron energy increases, the significance of multiple scattering and ionization diminishes, and the bremsstrahlung process becomes the most effective reaction in energy deposition. The energy deposition profile of electrons in the tungsten target indicates that higher incident electron energies lead to a shift of the maximum energy deposition location towards the inner layers of the target, and the energy deposition peak broadens. Analyzing the electrons transport inside the tungsten target reveals that a substantial portion of electrons with energies of 50–100 MeV passes through the wall and may exit from the back surface, potentially causing damage to equipment behind the tungsten wall. Additionally, secondary products of the reaction, such as photons, secondary electrons, and neutrons and their energy profiles are thoroughly studied. These secondary products can penetrate the target and activate materials in the equipment behind the plasma-facing components. For primary electrons below 1 MeV hitting tungsten, reflection process is significant. Analysis of primary and secondary runaway electrons in the tokamak's tungsten wall shows that electrons with energies of 0.1, 0.2, and 0.5 MeV predominantly interact within a first 0.1 mm layer, without passing through it. The secondary electrons can escape the tungsten target and impact other components, which making them an important consideration in runaway electron collisions with the tokamak wall. Produced photons, as one of the secondary products, also linearly increase with the rising energy of primary electrons. Also, the photoneutrons are produced only when runaway electrons with energies of 10 MeV and above collide with the target. These secondary products can penetrate the target and activate materials in the equipment behind the plasma-facing components.

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“…Parameters d and β for failure surface were obtained by using diametrical and axial compression tests [25]; the parameters R and P b for cap surface are obtained by using an instrumented cubic die with measurements of vertical and horizontal stress, the details calibration can be found in another paper [18,19]. The dependence of elastic parameter of Young's modulus E and Poisson ratio ν for elastic zone can be neglected in the modeling of die compaction because (11)…”

Section: Calibration Of the Constitutive Model Parametersmentioning

confidence: 99%

“…The potential for cracks has been recognized as a significant concern and often limits its application of powder metallurgy technology for the product of complex part geometries [1]. During the compaction, the areas of particles contact together and form a mechanical bond, and the bonds are quite week, and hence, the brittle fracture during ejection is likely to occur depending on the maximum principle stress [11]. However, other stresses such as direction stress may be also a driving force for crack initiation and propagation.…”

Section: Stress Statementioning

confidence: 99%

See 1 more Smart Citation

Stresses State and Mechanical Behaviors of the Green Body During Die Compaction and Ejection Process

Wang

Liu

et al. 2020

Acta Metall. Sin. (Engl. Lett.)

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Finite element simulations for metal powder compaction of a clutch plate were performed to examine the stresses during compaction, unloading, and ejection. To describe the mechanical behavior of compacted green body, a modified densitydependent Drucker-Prager Cap model was utilized to predict the stress and density distribution of the compacted clutch plate during loading and ejection stages. The results indicate that maximum tensile principal stress was a main driving force for the tensile crack initiation during ejection stage, and shear stress may be another driving force in both compaction and ejection stages for shear crack initiation. There were peak value of the stresses during ejection stage, and the stresses are in compressive state only during compaction stage. Therefore, the tensile crack initiation is not possible during compaction except shear crack. Hoop stress in the clutch plate is of less contribution to the crack initiation during compaction, unloading and ejection. Study of criteria of the crack initiation and fracture is necessary in order to obtain uniform density and crackfree components in the manufacturing of metal powder compaction.

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Thermal Shock Behavior Analysis of Tungsten-Armored Plasma-Facing Components for Future Fusion Reactor

Cited by 7 publications

References 29 publications

Finite Element Analysis and Experimental Verification of Thermal Fatigue of W-PFM with Stacked Structure

Finite Element Analysis and Experimental Verification of Thermal Fatigue of W-PFM with Stacked Structure

Runaway electrons and their interaction with tungsten wall: a comprehensive study of effects

Stresses State and Mechanical Behaviors of the Green Body During Die Compaction and Ejection Process

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