We present our studies of the parameters of helium beam plasma. The beam plasma was generated by a powerful focused electron beam propagating through helium atmosphere at a pressure of 25 Pa. The ...beam power varied in the range 80 to 1000 W. We have determined the electron beam parameters that enable one to generate a beam plasma with a density greater than 1016 m−3. Using the plasma ions, we have conducted treatment of polymer materials. It has been shown that the beam plasma treatment in the forevacuum range of pressure enhances the hydrophilic properties of fluoroplastic surfaces.
The results of using a forevacuum plasma electron source for obtaining gradient metal-ceramic materials are presented. The sintered material was located in a graphite crucible, which was heated by a ...wide electron beam to the temperature of 100 degrees lower sintering temperature for a given material. The sintering was carried out using a narrow-focused beam directed to the surface of the cermet powder. It is shown that when a coarse-grained aluminum oxide powder and fine-dispersed titanium powder are used, quite brittle samples are obtained. In the same time using of fine powder of aluminum and titanium, as well as their mixtures, allow to create a multilayer metal-ceramic sample with a variable composition, from titanium to aluminum.
Metasurfaces enable exceptional control over the light with surface-confined planar components, offering the fascinating possibility of very dense integration and miniaturization in photonics. Here, ...we design, fabricate, and experimentally demonstrate chip-size plasmonic spectropolarimeters, consisting of three gap-plasmon phase-gradient metasurfaces that occupy 120° circular sectors each, for simultaneous polarization state and wavelength determination. The spectropolarimeters diffract normally incident light to six predesigned directions, whose polar angles are proportional to the light wavelength, while contrasts in the corresponding diffraction intensities provide a direct measure of the incident polarization state through retrieval of the associated Stokes parameters. The proof-of-concept 96-μm-diameter spectropolarimeter operating in the wavelength range of 750–950 nm exhibits the expected polarization selectivity and high angular dispersion (0.0133°/nm for the |x⟩ channel). Moreover, we show that, due to the circular-sector design, polarization analysis can be conducted for optical beams of different diameters without prior calibration, demonstrating thereby the beam-size-invariant functionality. The proposed spectropolarimeters are compact, cost-effective, and robust and promise high-performance real-time polarization and spectral measurements.
In this paper, we review recent advances in the generation and study of beam plasma produced upon gas ionization by a stationary low-energy electron beam in the forevacuum pressure range (1–100 Pa). ...The features of the interaction of a stationary electron beam with the produced plasma during its transportation in a large-volume vacuum chamber, as well as the results of a study of the parameters of the plasma generated by the injection of an electron beam into a vessel with dielectric walls, are presented. It is shown that depending on the parameters of the electron beam, as well as the pressure and type of a gas, it is possible to create conditions for collective interaction with the ignition of a beam-plasma discharge characterized by an increased concentration and temperature of plasma electrons.
Metasurfaces based on gap surface-plasmon resonators allow one to arbitrarily control the phase, amplitude, and polarization of reflected light with high efficiency. However, the performance of ...densely packed metasurfaces is reduced, often quite significantly, in comparison with simple analytical predictions. We argue that this reduction is mainly because of the near-field coupling between metasurface elements, which results in response from each element being different from the one anticipated by design simulations, which are commonly conducted for each individual element being placed in an artificial periodic arrangement. In order to study the influence of near-field coupling, we fabricate meta-elements of varying sizes arranged in quasi-periodic arrays so that the immediate environment of same size elements is different for those located in the middle and at the border of the arrays. We study the near-field using a phase-resolved scattering-type scanning near-field optical microscopy (s-SNOM) and conducting numerical simulations. By comparing the near-field maps from elements of the same size but different placements we evaluate the near-field coupling strength, which is found to be significant for large and densely packed elements. This technique is quite generic and can be used practically for any metasurface type in order to precisely measure the near-field response from each individual element and identify malfunctioning ones, providing feedback to their design and fabrication, thereby allowing one to improve the efficiency of the whole metasurface.
The technology of isothermal storage of liquefied hydrocarbon gas (LPG) is proposed, which provides automatic control of the processes of steam condensation in an isothermal tank and regasification ...of LPG using a steam compression heat pump. The specified storage temperature of LPG is stabilized in the evaporator of the pump, and regasification of LPG with subsequent supply of the gaseous phase to the consumer is implemented in the condenser. The proposed technology allows to ensure accuracy and reliability of process control by reducing the spread of controlled parameters, ensuring their variation in a specified range. This is a significant reserve for intensification of thermal processes with a reduction of fire risk value and improvement of environmental safety, including due to the use of a harmless, noncombustible, explosionproof coolant. The optimal conditions are provided for storage and discharge of gas in large capacity tanks with minimum energy costs.
An efficient recombinant strain of the methylotrophic yeast
Pichia pastoris
was obtained; it produces active phospholipase A2 (PLA2) in a high yield. As a result of three stages of purification, a ...preparation of ~90% purity was obtained. The results of the evaluation of the reproducibility of chromatographic separation of PLA2 give grounds to consider the developed protocol acceptable for scaling; isolated phospholipase A2 can be used for industrial applications.
The paper presents results of investigation into the special features of physics of fore-vacuum plasma sources of ribbon electron beams. The main difficulties encountered in the development of ...sources of this type are demonstrated. Conditions that allow one to increase the emission current density with simultaneous preservation of high degree of beam current homogeneity are determined. On the basis of the described physical features in the fore-vacuum plasma sources operation, the main directions in the development of the electron sources generating beams in the fore-vacuum pressure range are proposed.
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