No 2 (2023)

At the HELIS ion accelerator, the dependence of the yield of nuclear DD reaction products (neutrons and protons) on the angle of rotation of a Ti and CVD diamond target relative to the axis of the D⁺ ion beam at energies E ≤ 35 keV was studied. Neutron detection was carried out by two independent methods: proportional counters filled with ³He and a scintillation detector with a stilbene crystal. Protons were detected using a diamond detector. The detectors were located on the side and behind the target. The CVD diamond target had a polycrystalline structure and texture with (100) grain orientation. The crystal structure of the titanium target was homogeneous and isotropic. The measurements showed the dependence of the neutron flux recorded by the detectors located on the side and behind the target on the orientation of the target made of textured CVD diamond in the deuterium ion beam at energies of 25 and 30 keV. The proton yield from the CVD diamond target showed a dependence on the target rotation angle at an energy of 25 keV. For the Ti target, no such effects were observed. The orientational dependence in the yield of neutrons and protons from textured diamond is explained by the effect of channeling deuterium ions in its structure.

The methods of scanning electron, atomic force, and magnetic force microscopy, together with measurements of the magnetic characteristics before and after exposure to pulses of a weak magnetic field (10–100 kA/m) of low frequency (10–20 Hz), were used to study the features of the surface state that determine the domain structure, magnetic properties and magnetic losses during magnetization reversal of ribbon amorphous Fe(Ni, Cu)(SiB) alloys obtained by ultrafast cooling by melt spraying on a rotating drum. Both surfaces of the foils were studied: the surfaces of the samples adjacent to the copper drum, which had an inhomogeneous structure characteristic of all rapidly quenched samples, and other sides of the foils, the surfaces of which were more even, which made them look shiny. When studying the surfaces of foils by atomic force microscopy after their magnetic pulse processing, no changes in the nature of the surface structure were found. The changes were recorded on the images of the shiny side of the samples by magnetic force microscopy. If no domain structure was observed before magnetic pulse treatment, then after magnetic pulse treatment, stripe domains with a width of 0.6–0.8 nm and closing domains with a width of 1.0–1.6 nm were found on structural defects, and in some areas of the surface, along with this, a weak magnetic contrast in the form of large and small domains with a shape close to triangular. It has been established that the magnetization reversal losses are largely related to the losses caused by eddy currents and are related to the domain width (about 1.5 nm), which depends only slightly on the modes of magnetic pulse processing. The obtained research results can be used to refine the technique for relieving stresses arising in the process of manufacturing amorphous ribbons.

The effect of fluence (1–7) × 10¹⁶ cm^–2 electrons with an energy of 30 keV on the concentration of color centers in aluminum oxide hollow particles micron-sized in comparison with bulk Al₂O₃ microparticles was studied. The analysis was carried out using diffuse reflectance spectra in the range from 250 to 2500 nm in situ. The radiation resistance of the microspheres under study was evaluated relative to micropowders from the difference diffuse reflectance spectra obtained by subtracting the spectra after irradiation from the spectra of non-irradiated samples. Changes in the difference diffuse reflection spectra of aluminum oxide microparticles and microspheres obtained with different electron fluences showed that with an increase in the induced electron fluence, absorption increases throughout the spectrum. It was found that the radiation resistance of aluminum oxide microspheres to the effects of electrons with an energy of 30 keV a fluence (1–7) × 10¹⁶ cm^–2 greater than the radiation resistance of Al₂O₃ microparticles. The increase in the radiation resistance of aluminum oxide hollow microparticles compared to the radiation resistance of aluminum oxide bulk microparticles is due to the low concentration of induced defects of the anionic sublattice.

Using electron microscopy methods, the effect of polymer-colloidal drilling fluids on the pore space in carbonate reservoirs of an oil and gas condensate field, was studied. It is shown that the impact of polymers included in drilling fluids changes the surface of the pore space of rocks. This affects the technology of developing oil fields and the intensification of oil production. At the same time, due to the deposition of polymer components in the pore space of the rock, the properties of the samples change. This must be taken into account when conducting petrophysical studies on samples, as well as in geophysical studies of the bottom-hole zone using methods with a small study radius. The results of morphological studies in the electron microscope of the pore space of rocks after the impact of polymer-colloidal drilling fluids, are presented. Polymer films formed from drilling fluid components are studied. It has been established that after drilling horizontal wells, the change in the wettability of the pore space is associated with the formation of a polymer film on carbonate crystals. The thickness of this film, measured by the direct method, is 60–200 µm in the studied samples. It is noted that these changes in the future can lead to errors in determining the petrophysical properties.

In the current work the computer simulations were performed to study the possibility of surface functionalization of low-K materials that are used as interlayer insulators within ultralarge integration devices with low-energy (up to 30 eV) noble gas atoms. The simulations were carried out using the ab initio density functional theory method assisted with molecular dynamics algorithms implemented in VASP package. The detailed trajectory analysis revealed the conditions under which the irradiation of incident He, Ne, Ar, Xe atoms with the energy up to 30 eV may result in the illumination of near-surface methyl groups responsible for hydrophobic properties of dielectric surface. Based on the data obtained the threshold energy (the minimum atom energy for CH₃-radical formation) was evaluated, and the mechanism peculiarities of such a process under light and heavy atom irradiation were studied. It was shown that in the energy range under consideration the interaction Ne, Ar, and Xe with methyl groups has mainly collisional mechanism, therefore with increase in mass of the incident particle the threshold energy increases. He atom irradiation, on the contrary, is capable to induce the perturbations of the electronic density around the methyl group that stimulate fast atom vibrations and result in CH₃-detachment.

The prospects of using crystals with asymmetric reflection geometry to determine the transverse size of relativistic electron beams based on the results of measurements of angular distributions of their radiation in a thin crystal for two distances between it and a coordinate detector are discussed. An experimental test of this technique was carried out using an imaging plate as a two-dimensional position-sensitive detector. Measurements were made for the electron energy of 255 MeV and reflection (220) in a silicon crystal with a thickness of 20 microns and a pixel size of 35 × 35 µm². The distances between the crystal and the detector were 0.5 and 1 m. The obtained values of the horizontal and vertical beam sizes \({{\sigma }_{x}} = 0.32 \pm 0.02\,\,~{\text{mm}}\) and \({{\sigma }_{y}} = 1.35 \pm 0.02~\,\,{\text{mm}}\) are in satisfactory agreement with the measurement results for optical transition radiation. The possibility of characterizing X-ray plates by comparing the measured and calculated PXR angular distributions for several reflecting planes of crystals with an asymmetric reflection geometry and an asymmetry parameter ε less than unity is discussed.

Computer simulations were used to calculate the energy spectra and angular distributions of reflected particles during bombardment of the tungsten surface with hydrogen and deuterium atoms with energies of 0.1–10 keV. A model was proposed that qualitatively explained the main regularities in the behavior of the spectra. The similarity of the energy spectra upon bombardment by hydrogen and deuterium atoms at the same collision velocities has been established. The angular distribution of reflected particles was universal in a wide range of initial energies of the bombarding atoms.