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Suche nach „[G.] [Lei]“ hat 3 Publikationen gefunden
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    NachhaltigElektrotechnik und MedientechnikIQMA

    Zeitschriftenartikel

    Y. Zhang, W. Ni, G. Song, H. Fan, Günther Benstetter, C. Niu, L. Liu, G. Lei

    Effect of intermittent He/D ion irradiations on W nano-fuzz growth over W targets

    Vacuum, vol. 173, no. March

    2020

    DOI: 10.1016/j.vacuum.2019.109146

    Abstract anzeigen

    The intermittent He/D ion irradiations of polycrystalline W have been performed at the ion energy of 50 eV by changing the time of the single irradiations and the irradiation temperature. All irradiated W specimens have been observed by scanning electron microscopy, and the effect of intermittent He/D ion irradiations on the W fuzz growth has been analyzed. The W fuzz growth over W targets does not show the clear dependence on the intermittent He/D ion irradiations, where the He/D ion fluence of the single irradiations typically varies from 5.0 × 1024 to 2.5 × 1025/m2. However, a slight change in the W surface temperature during the single He ion irradiations significantly affects the W fuzz growth rate. Analysis indicates that W fuzz growth is significantly affected by the total He ion fluence varying from 5.0 × 1024 to 5.0 × 1025/m2 and the irradiation temperature varying from 1100 to 1450 K. This current study will play a crucial role in understanding the W fuzz growth under the periodic He/D ion irradiations of W divertor in fusion reactors, such as ELMs.

    NachhaltigElektrotechnik und MedientechnikIQMA

    Zeitschriftenartikel

    L. Yan, Z. Bi, Y. Zhang, D. Liu, Y. Hong, H. Fan, Günther Benstetter, Y. Xia, L. Liu, G. Lei

    The evolution of He nanobubbles in tungsten under fusion-relevant He ion irradiation conditions

    Nuclear Fusion, vol. 59, no. 8

    2019

    DOI: 10.1088/1741-4326/ab2472

    Abstract anzeigen

    He-induced W nanofuzz growth over the W divertor target is one of the main limiting factors affecting the current design and development of fusion reactors. In this paper, based on He reaction rate model in W, we simulate the growth and evolution of He nanobubbles during W nanofuzz formation under fusion-relevant He+ irradiation conditions. Our modeling unveils the existence of He nanobubble-enriched W surface layer (<10 nm), formed due to the He diffusion in W crystal into defect sites. At an elevated temperature, the growth of He bubbles in the W surface layer prevents He atoms diffusing into the deep layer (>10 nm). The formation of W nanofuzz at the surface is attributed to surface bursting of high-density He bubbles with their radius of ~4 nm, and an increase in the surface area of irradiated W. Our findings have been well confirmed by the experimental measurements.

    NachhaltigElektrotechnik und MedientechnikIQMA

    Zeitschriftenartikel

    Y. Zhang, D. Liu, W. Ni, G. Song, H. Fan, Günther Benstetter, L. Liu, G. Lei

    Mass loss of pure W, W-Re alloys, and oxide dispersed W under ITER-relevant He ion irradiations

    Journal of Nuclear Materials, vol. 527

    2019

    DOI: 10.1016/j.jnucmat.2019.151800

    Abstract anzeigen

    In this study, polycrystalline W, W-Re alloys, and La2O3 and Y2O3 dispersion-strengthened W have been irradiated by our large-power materials irradiation experimental system (LP-MIES) at the irradiation temperature of 1360–1460 K. Our measurements show that the W nano-fuzz layer which is < 5.2 μm thick has been formed over all the specimens exposed to the low-energy (50 or 100 eV) and high-flux (1.37 × 1022–1.62 × 1022 ions/m2⋅s) He+ irradiations. The mass loss of the fuzz layer almost linearly increases with the He+ fluence, which does not show any dependence on the thickness of fuzz layer varying from 1.1 to 5.2 μm La2O3 and Y2O3 dispersions into W significantly suppress the growth of W fuzz, indicating that He diffusion and the evolution of He nano-bubbles in the near-surface can be significantly influenced due to the dispersion. After He+ (100 eV) irradiation at He+ fluence of 5.83 × 1026/m2, the mass loss of 0.1 vol% - 1.0 vol% La2O3-dispersed W is about 20% lower than the one of the pure W, and the La2O3 dispersed W exhibits the best erosion resistance among various W material grades. Our analysis indicates that both the surface sputtering of W fuzz by energetic ions and surface bursting of He nano-bubbles can be responsible for the mass loss of W under ITER-relevant He+ irradiations.