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Your search keyword '"ALIMOV, Vladimir Kh."' showing total 12 results
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12 results on '"ALIMOV, Vladimir Kh."'

6. Deuterium retention in chemically vapor deposited tungsten carbide coatings and hot-rolled tungsten exposed to low-energy deuterium plasma

Author

Alimov, Vladimir Kh. and Roth, Joachim

Abstract

Samples of chemically vapor deposited (CVD) coatings of tungsten carbides W45C55and W60C40and samples of hot-rolled tungsten were exposed to deuterium (D) plasma at sample temperatures ranging from 323 to 813 K, as a result of which the samples were irradiated with D ions with an energy of about 200 eV per D particle at a flux of D particles of about 1.1 × 1021D·m−2·s−1to a fluence of about 2 × 1024D·m−2. The concentration of deuterium in these samples was examined by the D(3He,p)4He nuclear reaction. Based on the measured deuterium depth profiles and assuming that these profiles are determined by diffusing D atoms, the diffusion coefficients of deuterium in the CVD tungsten carbide coatings were determined. Using these diffusion coefficients, an estimate of the Arrhenius relation for the diffusion coefficients of deuterium in CVD tungsten carbide coatings was obtained: D= 2.5 × 10–3exp(− 1.12 eV/kT) m2·s−1, where Tis temperature expressed in Kelvin, and k is the Boltzmann constant. The concentration of trapped deuterium in the bulk of CVD tungsten carbide coatings is practically independent of the stoichiometry of the coatings. It decreases from about 5 × 10–2to about 7 × 10–4D/(W + C) with an increase in the deuterium plasma exposure temperature from 373 to 813 K. The concentration of trapped deuterium in hot-rolled tungsten, expressed in units of the D/W atomic ratio, is more than an order of magnitude lower than the concentration of deuterium in tungsten carbides, and also decreases with increasing plasma exposure temperature.

Published
2024
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7. Dynamics of Hydrogen Isotope Absorption and Emission of Neutron-Irradiated Tungsten

Author

TOYAMA, Takeshi, YAJIMA, Miyuki, OHNO, Noriyasu, KUWABARA, Tatsuya, ALIMOV, Vladimir Kh., HATANO, Yuji, TOYAMA, Takeshi, YAJIMA, Miyuki, OHNO, Noriyasu, KUWABARA, Tatsuya, ALIMOV, Vladimir Kh., and HATANO, Yuji

Abstract

This overview presents recent results regarding hydrogen isotope absorption and emission dynamics in neutron-irradiated tungsten (W) using our recently developed Compact Diverter Plasma Simulator (CDPS), a linear plasma device in a radiation-controlled area. Neutron irradiation to 0.016 - 0.06 displacement per atom resulted in a significant increase in deuterium (D) retention due to trapping effects of radiation-induced defects. We analyzed the dependency of D retention on the D plasma fluence by exposing neutron-irradiated pure W to D plasma at 563 K over a range of D fluence values. The total retention was revealed to be proportional to the square root of D fluence, indicating that the implanted D atoms first occupy the defects caused by neutron-irradiation near the surface and then the defects located in deeper regions. We further investigated the effects of post-plasma annealing on D emission; neutron-irradiated pure W was exposed to D plasma at 573 K and was then annealed at the same temperature for 30 hours. Approximately 10% of the absorbed D was released by annealing, suggesting that a heat treatment of the plasma-facing component of a fusion reactor at moderately elevated temperatures could contribute to the removal of accumulated hydrogen isotopes. The experimental results obtained in this study were only available by investigating neutron-irradiated specimens with the CDPS system, which will be essential for future studies of material behavior and plasma-wall interactions in the fusion reactor environment., source:https://doi.org/10.1585/pfr.15.1505081

Published
2022

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