Depth synergistic effect of irradiation damage on tungsten irradiated by He-ions with various energies

Liu, Y.L.; Lu, Eryang; Song, Lili; Bai, Ruoyu; Xu, Qiu; Jin, Shuoxue; Zhu, Te; Cao, Xingzhong; Zhang, Q.L.; Yuan, Daqing; Wang, Boyu; Ge, Liya

doi:10.1016/j.jnucmat.2019.02.008

Cited by 5 publications

(5 citation statements)

References 56 publications

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“…Compared with the 200 keVion irradiated W-2, the S parameters of the sequential-ion irradiated W-3 are reduced in the range of 58-249 nm, as shown in Fig. 3b and c. This is due to the trapping of He atom at vacancy-type defects and the formation of vacancyhelium complexes [3,10]. A turning point between 1073 and 1273 K is observed in all figures, which will be discussed later.…”

Section: Evolution Of the Type And Associated Intensities Of The Vacamentioning

confidence: 78%

“…τ m is conducted by the equation Fig. 1 a He-ion irradiation damage (dpa) in W-1, W-2, and W-3 and b the corresponded He atom concentration (at.%) as a function of positron penetration depth (nm) with SRIM calculations which represents the mean positron annihilation lifetime of the effective open volume defects in the whole sample [3,30]. As shown in Tables 2 and 3, the free state positron annihilation intensity reached ~ 99% in both well-annealed W and W5Re.…”

Section: Evolution Of the Type And Associated Intensities Of The Vacamentioning

confidence: 99%

“…Tungsten (W) is widely considered as the candidate for plasma facing materials (PFMs) in fusion reactor [1][2][3]. However, under the deuterium-tritium fusion reaction, PFMs-W has to withstand tremendous damages produced by high energy neutron (~ 14 MeV) and high thermal flux (~ 10 MW•m −2 ).…”

Section: Introductionmentioning

confidence: 99%

“…PAS is an effective and convenient technique to study the irradiation-induced vacancy-type defects, such as vacancy, vacancy cluster, vacancy-type dislocation loops as well as vacancy-impurity complex [11][12][13][14]. Positron is exclusively sensitive to vacancies, providing information of the size, density and depth distribution of vacancy-type defects [3,15,16]. Sato et al [17] took the PAS technique to study the change of the hydrogen decorated vacancies in Ogorodnikova et al [18] applied the PAS to investigate W exposed to 21.6 MeV protons and found that proton irradiation mainly induced the mono-vacancies.…”

Section: Introductionmentioning

confidence: 99%

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Thermal kinetics of micro-defects in He-ion implanted W and W5Re alloys

Liu

Song

et al. 2021

Tungsten

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To investigate the thermal evolution of vacancy-type defects in He-ion irradiated W and W5Re alloy, different isochronal annealing treatments from 373 to 1273 K were conducted on the irradiated materials. Positron annihilation spectroscopy including positron annihilation lifetime spectroscopy and Doppler broadening spectroscopy were mainly used to characterize the micro-defects evolution. The results showed that the thermal evolution characteristics of defects in both W and W5Re were similar. After He-ion irradiation, mono-vacancies with positron annihilation lifetime of ~ 190 ps were detected in W, together with a large amount of dislocation loops with positron annihilation lifetime of ~ 150 ps in W5Re alloys. The coarsening of vacancy clusters at the expense of small vacancy clusters was the main thermal evolution feature of vacancy-type defects in both W and W5Re when annealing temperature increased to 1073 K. In this progress, the positron annihilation lifetime increased to ~ 350 ps (clusters composed of 4 –8 mono-vacancies) in both W and W5Re. As the temperature increased to 1273 K, the positron annihilation lifetime decreased to ~ 240 ps, which was attributed to a significant population reduction of the dislocation loops, the dissociation of large HenVm complexes and the annealing of micro-voids in both W and W5Re. The vacancy-type defects in W5Re were more susceptible to the annealing temperature because of the formation of vacancy cluster-Re complexes. Re clusters in irradiated W5Re alloy could serve as the nucleation sites of He bubbles, which promoted the swelling and protrusion formation on the surface.

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Section: Evolution Of the Type And Associated Intensities Of The Vacamentioning

confidence: 78%

Section: Evolution Of the Type And Associated Intensities Of The Vacamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal kinetics of micro-defects in He-ion implanted W and W5Re alloys

Liu

Song

et al. 2021

Tungsten

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“…The S parameters at the positron energy less than 2 keV are relatively large, which would be contributed to two factors. One is that the low-energy positrons have shallow injection depth, the other is that the positrons after thermalizing diffuse to the surface and annihilate with the electrons in the surface [36]. The H or He ions with relative high (dozens of keV) energies irradiated the samples, resulting in the production of a lot of vacancy-type defects, which can be informed from the SRIM simulation.…”

Section: Db-spba Analysismentioning

confidence: 99%

Evolution of Defects in CVD-W Irradiated by H/He Neutral Beam Using Positron Annihilation Spectroscopy

Xia

Liu

Gong

et al. 2021

Metals

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One of the key problems for the application of nuclear fusion energy is to select the suitable plasma facing materials (PFMs). Among the W-based materials, CVD-W exhibits some unique advantages. In order to estimate the performance of CVD-W under the fusion environment, the vacancy-type defects and their evolution are investigated by the Doppler-broadening slow positron beam analysis (DB-SPBA) combined with SEM (scanning electron microscope). There are two kinds of neutral beam irradiation, the pure H neutral beam and the H + 6 at.% He neutral beam irradiation, which are performed at the neutral beam facility GLADIS (IPP, Germany). The surface temperatures of CVD-W irradiated by H (H + 6 at.% He) are 850 and 1000 (700 and 800 °C). By comparing the samples under different conditions, the defect evolution of CVD-W is obtained. As for the pure H neutral beam irradiated samples, the DB-SPBA results demonstrate that the CVD-W sample at the surface temperature of 1000 °C, compared to the 850 °C sample, shows a decrease in S parameters, which is due to the reduction of vacancy-type defect concentration. The defect damage layer in 1000 °C sample is narrower than that of 850 °C sample and the defect type tends to be consistent in 1000 °C sample. The SEM results suggest that the surface damage of the 1000 °C sample was recovered to some extent. As for the H + 6 at.% He neutral beam irradiated samples, compared with the CVD-W sample at the surface temperature of 700 °C, the 800 °C sample shows an increased S parameters, which can be attributed to the volume increase of vacancy-type defect. The defect damage layer in the 800 °C sample is wider than that of the 700 °C sample. Both the H + 6 at.% He irradiated samples show complex defect types. The surface of the 800 °C sample exhibits more dense pinhole damage structures compared to that of the 700 °C sample.

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