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.

Stable configurations of point radiation defects of tungsten near the surface were investigated within the density functional theory. The emergence of an self-interstitial atom leads to formation of a crowdion. The transformation of this configuration into a configuration with an adsorbed W atom is a thermally activated process with the energy barrier of 1.38 eV. When a single vacancy emerges near the crowdion close to the surface, a recombination occurs. Impurity atoms in the vacancy near the surface are capable of blocking the recombination process, acting as a factor that increases the radiation damage of tungsten.

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.