Vol 83, No 11 (2019)

The problem of heat distribution in metallic materials irradiated by sharply focused electron beams when there is no heat exchange between the target and the external environment is considered via mathematical modeling. The degree of heating the surfaces of different homogeneous metal targets by kilovolt electrons is estimated.

Features of the sedimentation of lakes Bolshoi Kisegach and Turgoyak (Southern Urals) are described by studying the magnetic fractions and magnetic properties of bottom sediments via scanning electron microscopy. The magnetic fraction of lacustrine sediments consists of authigenic and allothigenic minerals.

Scanning electron microscopy and scanning probe microscopy are used to examine the surface morphology of aluminum foils exposed to anodizing in acidic solution. Anodizing in the potentiostatic mode is shown to form a uniform honeycomb nanostructure on the foil surface, where the average distances between the centers of neighboring cells and the cell heights are proportional to the anodizing voltage. The specific electric capacitance of nanostructured anodic aluminum foils covered with an oxide layer via atomic layer deposition (ALD) is studied. The specific electric capacitance of nanostructured foils is established as a linear function of anodizing voltage and an inverse function of the number of ALD cycles.

The main angular characteristics and resulting semi-empirical equations for back-scattered electrons of medium energy (1–30 kV) are calculated. The results from an analysis are used to develop an optimized detector system of back-scattered electrons for scanning electron microscopes to visualize subsurface microstructures and improve topographic contrast. These results contribute to solving problems of the three-dimensional visualization of surface topography and selective tomography of the subsurface architecture of micro-objects.

Physical features of the formation of a low-pressure volume discharge in a flat-pack diode are demonstrated using a kinetic description of the electron and ion plasma subsystems. Modeling allows all details of this process to be followed, including the evolution of the distribution functions of electrons and ions over energies at all stages of breakdown development. The mechanism behind the formation of the flow of ions to the anode in the nonstationary phase of breakdown is revealed.

One-dimensional flows of charged particles with opposite sign of charge moving in one direction are considered for an electronic diode (or diode with negative ions) shot through by positive ions, and an ionic diode shot through by relativistic electrons. Options with varying extent of spatial charge compensation at the output of the diode are investigated, along with full compensation for charge, current, and magnetic field.

Major patterns of ion beam transport in a system with ballistic focusing are studied via numerical modeling. It is shown that the efficiency of transporting a beam of metal ions at 0.66 A and an ion energy of 1–3 keV depends on the voltage bias and plasma density in the beam’s drift space. Incomplete compensation for high-speed ions in the beam transport channel lowers the potential and (under certain conditions) produces a virtual anode. The ion-electron emission of electrons from targets and grid electrodes is an additional mechanism of compensating for the spatial charge of a beam of metal ions.

The surface temperatures of specimens made of A7 grade aluminum alloy and VT1-0 grade titanium alloy are measured with a high-speed infrared pyrometer during the impact of a pulsed electron beam with different densities of the pulse energy. Numerical modeling of the thermal fields under the same conditions reveals good similarity to the experimental data and confirms that the heating rate of a sample’s surface depends on the basic characteristics of the electron beam.

A special type of diffusive discharge (glow discharge) on which a low-current spark discharge is superimposed is created experimentally in a gas flow, in the form of atmospheric pressure plasma jets. The flow of current in the discharge gap is a steady regime of periodical current pulses. A highly efficient portable low-temperature nonequilibrium argon plasma source (the PortPlaSter) is designed on the basis of this glow discharge with superimposed low-current spark discharges.

The synthesis of plasmonic photonic crystal SiO₂–Ag nanostructures by deposition of silver nanoparticles is considered. The technique includes the physical sputtering of a silver target with a kiloelectronvolt argon ion beam onto silica microspheres obtained according to Stöber. The plasmon resonance effect is shown to be interrelated with the optical properties of nanostructured supports and the morphology of aggregate structures of silver nanoparticles (clusters).

The partial pressure of vapors of silicon and such metals as silver, copper, and tantalum is estimated and Ag–Si and Ta–Si systems are modeled thermodynamically. Nanoparticles of two types (core–shell and Janus-like) are obtained experimentally via high-temperature gas-phase synthesis using a direct-action electron accelerator. Characteristic features of the formation of composite nanoparticle structures are revealed by means of molecular dynamics, based on modified embedded-atom potentials.

Two samples of the Chelyabinsk meteorite are examined via scanning synchrotron radiation X-ray fluorescence microanalysis. The spatial distribution of several chemical elements is studied, and the patterns of localization are obtained for germanium and copper. The most pronounced correlations between elements are investigated: the relationship between the germanium and copper localization and specific minerals.