Development and application of the intense slow positron beam at IHEP

王宝义,; 马雁云,; 王平,; 曹兴忠,; 秦秀波,; 张哲,; 于润升,; 魏龙,

doi:10.1088/1674-1137/32/2/016

Cited by 26 publications

(7 citation statements)

References 3 publications

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“…Positron annihilation Doppler broadening (PADB) was used to detect vacancy-type defects [36][37][38][39] at the Key Laboratory of Nuclear Techniques Multi-research Center, Institute of High Energy Physics, Chinese Academy of Sciences [40]. The measurement was carried out at room temperature with an energy-variable slow positron beam.…”

Section: Analysis and Characterization Methodsmentioning

confidence: 99%

Blister-dominated retention mechanism in tungsten exposed to high-fluence deuterium plasma

et al. 2020

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To investigate the effect of blistering on hydrogen isotope (HI) retention, a series of deuterium plasma exposures were performed using recrystallized tungsten samples at 500 K with high fluences up to 1.0 × 10 28 ions m −2 in the linear plasma device STEP. An increase of blister density and deuterium retention was observed with increasing plasma fluence. Based on the simulation of the thermal desorption spectra using TMAP, defects with different detrapping energies are found to be located at a depth of tens of microns, which coincides with the depth of the grain boundaries (GBs) close to the surface. The defect characterizations using transmission electron microscopy and positron annihilation Doppler broadening identified the defects as dislocation type and vacancy type, which were created by blistering. It is suggested that these defects can diffuse deep into the material, and the interaction between the diffusion of the defects and GBs causes a peculiar deuterium desorption spectrum over plasma fluences. Additionally, these blister-induced defects are the main source of deuterium retention. Regarding the effect of the blister-induced defects on deuterium retention, a blister-dominated retention mechanism is proposed to describe HI retention in conditions when blistering is severe as in this study. This investigation provides a new insight into the effect of blistering on retention and the modelling of retention in a tokamak edge plasma environment.

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Section: Analysis and Characterization Methodsmentioning

confidence: 99%

Blister-dominated retention mechanism in tungsten exposed to high-fluence deuterium plasma

et al. 2020

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“…Doppler broadening spectrometry of positron annihilation (DBS-PA) tests were carried out at room temperature with an energy-variable slow positron beam at the Key Laboratory of Nuclear Analysis Techniques, the institute of high energy physics (IHEP), the Chinese Academy of Sciences. More detail on the DBS-PA technique can be found elsewhere [16]. Since the damage depth of 500 keV argon irradiation in tungsten is within ~250 nm, slow positrons were utilized in this work to obtain the information about the depth distribution of the irradiation-induced vacancy-type defects.…”

Section: Dbs-pa and Tds Measurementsmentioning

confidence: 99%

Deuterium occupation of vacancy-type defects in argon-damaged tungsten exposed to high flux and low energy deuterium plasma

et al. 2016

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Doppler broadening spectroscopy in the positron annihilation technique (DBS-PA) has been employed to investigate the defect properties in argon-damaged tungsten exposed to low-energy and high flux deuterium plasma. Argon ion irradiations with energy 500 keV are performed for tungsten samples with various levels of damage. The remarkable increment of the S parameter in DBS-PA indicates the introduction of vacancy-type defects in argon irradiated tungsten. An increase of ion fluence results in a continuous increase of the S parameter until saturation. Unexpectedly, a much higher fluence leads to a decrease of the S parameter in the near surface, and the (S,W) slope changes greatly. This should be associated with the formation of argon-vacancy complexes in the near surface produced by the excessive implanted argon ions. With deuterium plasma exposure, a significant decrease of the S parameter occurs in the pre-irradiated tungsten, suggesting the sharp reduction of the number and density of the vacancy-type defects. The thermal desorption spectroscopy results demonstrate that the argon-damaged tungsten, compared to the pristine one, exhibits an enhanced low-temperature desorption peak and an additional and broad high-temperature desorption peak, which indicates that deuterium atoms are trapped in both low-energy and high-energy sites. All these observations directly indicate the deuterium occupation of irradiation-induced vacancy defects in damaged tungsten, which is responsible for the remarkable increase of the deuterium retention in comparison with the pristine one.

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“…Positron annihilation technology (PAT) is based on the detection of gamma photons emitted due to positrons annihilation in materials, so that the information about the electron momentum distribution and defect microstructure in the sample can be extracted. The positron injection was carried out at room temperature using an energyvariable slow positron beam at the Institute of High Energy Physics, Chinese Academy of Sciences [21]. Positrons were generated by a 22 Na radiation source and the positron energy was continuously adjustable (from 0.5 keV to 20.5 keV).…”

Section: Methodsmentioning

confidence: 99%

Effect of rhenium on defects evolution behavior in tungsten under irradiation

Wang¹,

Gao²,

Zhu³

et al. 2021

Nucl. Fusion

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The influence of the transmutation element rhenium (Re) on defect evolution in tungsten (W) during irradiations with heavy ions and deuterium (D) plasma was investigated. Rolled W and W–5Re alloy (Re concentration 5 wt.%) were irradiated with 500 keV iron ions to 0.06 and 0.6 dpa (displacement per atom), and deuterium plasma at 38 eV/D to a fluence of 2.2 × 1025 D m−2 at ∼373 K. The results of Doppler broadening spectroscopy by the positron annihilation technique indicate that more or larger vacancy-type defects were produced in W than in the W–5Re during Fe ion irradiation, suggesting the important role of Re on inhibiting the migration and/or clustering of vacancies. The much smaller and shallower blistering in W–5Re than in W after the same D plasma exposure points to the pinning effects on dislocations by Re. The total retained D amounts in W–5Re and W materials are comparable, but with very different concentration profile at corresponding depth. This is explained by the blister formation exerting influence on the D inward diffusion. Demonstrating the important role of Re on the defect evolution in W under irradiation, the present work provides an enhanced understanding on the possible effects of neutron irradiation on the performance of plasma-facing materials in future fusion devices.

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Development and application of the intense slow positron beam at IHEP

Abstract: Bao-Yi( ) MA Yan-Yun( ) WANG Ping( ) CAO Xing-Zhong( ) QIN Xiu-Bo( ) ZHANG Zhe( ) YU Run-Sheng( ) WEI Long( ) 1)

Cited by 26 publications

References 3 publications

Blister-dominated retention mechanism in tungsten exposed to high-fluence deuterium plasma

Blister-dominated retention mechanism in tungsten exposed to high-fluence deuterium plasma

Deuterium occupation of vacancy-type defects in argon-damaged tungsten exposed to high flux and low energy deuterium plasma

Effect of rhenium on defects evolution behavior in tungsten under irradiation

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