The influence of irradiation in hydrogen plasma with oxygen impurity on the penetration of hydrogen isotopes through the surface of tungsten, through the surface of beryllium and aluminum layers on tungsten, and through the tungsten-coating interface was studied. It was shown that all these processes are accelerated in the presence of oxygen impurity in plasma. A conclusion is made that detritisation of the surface of both in the conditions of a fusion reactor tungsten and beryllium is possible.

In this work, the results of the irradiation of untreated, preliminarily Ar+-bombarded and Cr-coated samples of zirconium alloy E110 (Zr-1%Nb) with deuterium atoms and ions of deuterium plasma were compared with the results of their exposure to superheated water steam (673 K, 11 MPa; 673 K, 0.1 MPa; 633 K, 0.1 MPa). It was concluded that, despite of the difference in the rates of the oxide layer formation, the features of hydrogenation are similar under the two kinds of impact. However, the hydrogen uptake under irradiation occurs hundreds of times faster than during the steam test. The most effective hydrogenation was achieved under irradiation of the E110 sample with 300-500 eV/at ions of deuterium plasma without oxygen. These circumstances allow suggesting the irradiation with ions of hydrogen plasma as an accelerated hydrogenation test of zirconium alloys and protective coatings under conditions simulating the environment of light-water reactor's core. The proposed method could be realized using a simple plasma device and it does not require high power consumption or special qualification of staff. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Features of plasma-induced formation of the surface oxide layers on zirconium alloy E110 (Zr-1%Nb) as well as hydrogen resistant properties of these layers are studied. It is shown that irradiation of the E110 sample with 1 keV ions of He + O-2 plasma produces the oxide layer depleted by oxygen nearby the surface. The onset of the intensive hydrogen penetration into the ion-irradiated sample during the steam test (673 K, 0.1 MPa) appears to occur 1500 hours later than into the untreated one.

The ability of yttria layers to act as barriers to hydrogen desorption is studied. The possibility is discussed of using these layers to reduce losses of tritium from a neutron tube target. The composition of a multilayer target in which tritium desorption is reduced by an accumulator layer (zirconium) and barrier layers (yttria) is described. It is shown that deuterium losses observed in thermal desorption tests over 4 h at 623 K fell by 85–87%. A system is proposed for the renewal of an external barrier layer subjected to sputtering by a deuteron ion flux.

Patterns of hydrogen isotope trapping and retention are investigated by applying hydrogen ion radiation to nickel samples free of oxidation, tungsten samples with oxide layer on their surfaces, and tungsten samples with aluminum coating with oxide layer. It is found that hydrogen isotope desorption upon hydrogen ion plasma irradiation occurs in samples of tungsten and tungsten with aluminum coating, but not in nickel samples. It is concluded that hydrogen isotope transport through the tungsten–aluminum interface is initiated when one surface of a samples is irradiated with hydrogen plasma ions.

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.

An investigation on mechanisms of hydrogen and deuterium trapping in tungsten during irradiation by hydrogen ion plasma with oxygen impurity using the methods of thermal desorption spectrometry (TDS) and secondary ion mass spectrometry (SIMS) is presented in this paper. It was shown that almost 40% of trapped particles were retained in the surface oxide layer after first implantation of deuterium. Subsequent irradiation by hydrogen plasma with oxygen impurity lead to the increase of oxygen concentration and hydrogen trapping in the oxide layer and tungsten bulk. In the next cycle, which started with deuterium implantation, oxygen concentration in the oxide layer decreased and some hydrogen was removed from tungsten. Then an increase of hydrogen and oxygen concentration in the sample repeated during irradiation with ions of (H2 + 1 at. % O2) plasma. The same sequence of processes was observed during subsequent irradiation cycles.

The results of studying the trapping and retention of hydrogen and deuterium in MPG-8 graphite under sequential irradiation with ions of deuterium and hydrogen plasma are presented. The effect of the energy and density of the hydrogen-ion flux, the impurity of oxygen in the plasma, and the temperature of the irradiated samples on a decrease in the deuterium concentration and hydrogen trapping in graphite is studied. Based on the analysis of experimental data, it is suggested that the observed effect of deuterium removal can be explained by the chemical sputtering of graphite.

The results of the comparative analysis of low-temperature desorption of deuterium from tungsten coated with aluminum and yttrium films under the irradiation by hydrogen plasma with oxygen impurity are presented. The irradiation of aluminum or yttrium coating by H2+1%O2 plasma leads to the desorption of implanted deuterium from the samples. It was shown that the number of atoms desorbed depends on the sign of enthalpy of hydrogen solution in the metal film.

Effect of yttria and titanium nitride coatings on features of deuterium desorption from titanium layer is investigated. It is shown that both coatings significantly raise the temperature of maximum of deuterium thermal desorption from titanium under linear heating and prevent desorption under prolonged keeping at the operating temperature of a neutron tube target. However, under irradiation with ions of H-2 + O-2 plasma the barrier properties of titanium nitride appear to degrade.

The results on trapping and desorption of hydrogen isotopes under irradiation of zirconium by deuterium atoms of thermal energies are presented. It is shown that the addition of oxygen to the operating gas during the irradiation causes the increase of the oxide layer thickness, the amount of hydroxyl groups in it and deuterium trapping in zirconium. Accelerated transport of deuterium atoms through the oxide layer saturated by hydroxyl groups is observed. Mechanisms of trapping and desorption of hydrogen isotopes and the role of oxygen in these processes are discussed.

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.

The effect of ion irradiation and deposited yttrium-oxide layers on deuterium desorption from titanium deuteride is studied. The features of deuterium desorption during the interaction of hydrogen ions with a titanium-deuteride layer are revealed. It is shown that gas desorption decreases both under hydrogen-ion irradiation with energies of < 1000 eV and the deposition of an yttrium oxide layer.

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.

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.

Both the latest and earlier achieved results on gas exchange processes on metal surfaces (including stainless steel, titanium, zirconium, tungsten with deposited aluminum oxide coating) under hydrogen atom or plasma irradiation with occasional oxygen impurity are presented in the paper. Mechanisms and regularities of these processes are discussed. It is demonstrated that surface oxide layer properties as a diffusion barrier strongly depend on external influence on the surface. In particular, it is revealed that low energy hydrogen ion irradiation could slow down hydrogen desorption from metals. Hydrogen atom or ion irradiation combined with simultaneous oxygen admixture accelerates hydrogen desorption from metals.

The paper presents the results of investigations on hydrogen trapping in the carbon films deposited in the plasma of four experimental devices (two laboratory stands, plasma accelerator QSPA-T and tokamak Tore Supra) covering a wide range of deposition conditions. The features of hydrogen trapping common for these devices are evaluated. It is shown that the trapping in the films of the certain device increases with the decrease of the deposition rate. Hydrogen from residual gas constitutes nearly half, or bigger part of the whole retention in the deposited films. It is trapped through inelastic interaction of the particles with the surface (“potential” mechanism of trapping). Ion irradiation and oxygen impurities activate the “potential” trapping. In conclusion some implications from the presented data are drawn.

The paper presents the results of experimental investigation of energy and flux dependences of hydrogen isotopes and oxygen trapping in carbon materials (carbon fiber composite and pyrolitic graphite), and metals (stainless steel and nickel) under irradiation in the deuterium gas discharge plasma with and without oxygen addition. The dependence of hydrogen trapping on ion energy, ion current density, oxygen addition in deuterium plasma are presented and analyzed. The sorbed molecules, containing hydrogen atoms from the residual gas and deuterium atoms of the working gas are shown to be the important source of hydrogen trapping in both carbon based materials and stainless steel. Irradiation of the SS vacuum vessel with the neutrals or/and ions of (D-2 + O-2) plasma initiate the hydrogen diffusion from the vessel wall and H-2, HD, D2O, HDO, H2O molecule formation on the wall surface. Trapping of the low energy plasma particles and the particles from the sorbed molecules as well as modification of working gas composition are considered as the processes provided at the expense of the potential energy of plasma particles with respect to the surface and occurred through their inelastic collisions with the surface. The hydrogen trapping occurred due to "potential" processes was named as "potential", and in contrast the trapping of fast particles due to their kinetic energy was labeled as "kinetic". (C) 2013 Elsevier B.V. All rights reserved.