The paper presents the results of investigation of gas exchange through stainless steel surface of the plasma chamber under irradiation with hydrogen atoms in oxygen atmosphere or oxygen contaminated ...hydrogen plasma. Dependence of this process on various irradiation parameters, such as the metal temperature, energy of irradiating ions, gas composition of plasma are studied. It is shown, that desorption from stainless steel is activated with the increase of the plasma chamber walls temperature and energy of irradiating ions. Hydrogen release occurs also under irradiation of the walls by helium and argon plasmas added with oxygen, however the amount of released hydrogen is several times lower than in the case of irradiation with oxygen contaminated deuterium plasma.
A mathematical model of surface cracking under pulsed heat load was developed. The model correctly describes a smooth brittle–ductile transition. The elastic deformation is described in a ...thin-heated-layer approximation. The plastic deformation is described with the Hollomon equation. The time dependence of the deformation and stresses is described for one heating–cooling cycle for a material without initial plastic deformation.
The model can be applied to tungsten manufactured according to ITER specifications. The model shows that the stability of stress-relieved tungsten deteriorates when the base temperature increases. This proved to be a result of the close ultimate tensile and yield strengths. For a heat load of arbitrary magnitude a stability criterion was obtained in the form of condition on the relation of the ultimate tensile and yield strengths.
The results of tests of plasma treatment of zirconium and deposition of protective yttrium coatings used as the methods of protection of zirconium components of light water reactor cores against ...hydrogenation are detailed. The amount of hydrogen in the treated sample exposed to superheated steam for 2500 h at temperature
T
= 400°C and pressure
p
= 1 atm was five times lower than the corresponding value for the untreated one. The amount of hydrogen in the sample coated with yttrium remained almost unchanged in 4000 h of exposure. A plasma method for rapid testing for hydrogen resistance is proposed. The hydrogenation rate provided by this method is 700 times higher than that in tests with superheated steam. The results of preliminary experiments confirm the possibility of constructing a unit for batch processing of the surfaces of fuel rod claddings.
In the paper, a simple and easy to operate stand is presented that allows irradiating the surface of solids by gas discharge plasma ions in the energies ranging from 5 to 40 keV. The results of first ...experiments are shown. Ion current parameters on the irradiated sample using gas discharge are presented for different gases.
A two-stage optical parametric amplifier (OPA) design that provides over −5 × 107 gain at 1053 nm is presented. Noise level of the parametric amplifier in the signal wave propagation direction was ...2 × 10−6 from the signal level. The parasitic parametric oscillation under intense pump wave and its contribution to the OPA output was measured to be less than 8%.
The patterns of gas exchange between deuterium plasma and the walls of a vacuum chamber made from 12Cr18Ni10Ti (0.12% C, 18% Cr, 10% Ni, less than 1% Ti) stainless steel and irradiated with deuterium ...atoms in an atmosphere of deuterium with the addition of oxygen or with ions and atoms of a discharge in deuterium with the addition of oxygen are studied. It is demonstrated that irradiation of the surface of stainless steel under the indicated conditions promotes the diffusion of hydrogen from stainless steel; the implantation of deuterium into stainless steel; and the production on the surface and the desorption of H
2
O, HDO, D
2
O, HD, and H
2
molecules. Almost all oxygen from the gas mixture in the oxygen concentration range from 0.5 to 30 at % is involved in the production of protonated and deuterated water molecules on the surface. When the oxygen concentration in the mixture of deuterium with oxygen is increased, the release of hydrogen from steel is enhanced. The amount of deuterium captured by stainless steel is lower than the amount of hydrogen removed from it. It is demonstrated that the diffusion of hydrogen towards the surface, its reactions with deuterium and oxygen from the working gas, and the trapping of deuterium in steel may be driven by consecutive surface exothermic reactions initiated by the interaction of deuterium atoms and ions with chromium oxide on the surface of stainless steel.
A study of the K + → π 0 e + νγ decay The NA62 collaboration; A. Kleimenova; S. Padolski ...
The journal of high energy physics,
09/2023, Letnik:
2023, Številka:
9
Journal Article
Recenzirano
Odprti dostop
Abstract A sample of 1.3 × 105 K + → π 0 e + νγ candidates with less than 1% background was collected by the NA62 experiment at the CERN SPS in 2017–2018. Branching fraction measurements are obtained ...at percent relative precision in three restricted kinematic regions, improving on existing results by a factor larger than two. An asymmetry, possibly related to T-violation, is investigated with no evidence observed within the achieved precision.
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