Physics of Atomic Nuclei最新文献

Plasma cleaning with simultaneous polishing by a jet electric discharge is more efficient than electrochemical polishing. The paper discusses the processes arising during the interaction of an electric discharge with solutions of inorganic substances, and studies the propagation of an inorganic discharge in a liquid on the surface of various materials (NaCl, NH₄NO₃, and discharge in glycerol). A NH₄NO₃ solution is shown to be the most effective electrolyte. We report on current‒voltage characteristics obtained for an electric discharge between a jet electrolytic cathode and a solid anode, as well as for a multichannel discharge in a jet electrolytic cathode at different jet lengths and diameters.

A distinctive feature of the “quasi-frozen” spin mode in the synchrotron is the installation of special elements with crossed magnetic and electric fields in straight sections that compensate the spin rotation from the MDM components on the arcs. Moreover, because of the presence of the longitudinal length and the momentum spread inside the beam, spin rotation may occur incoherently. In order to suppress this effect, sextupoles are installed, which also affect suppression of chromaticity.

This article is in response to a reference to my work as a work in which the expression for the density of the charge induced by the point charge between two infinite plane-parallel plates is in the form of an infinite series. Indeed, in my article there were formulas that I obtained for the Green’s function, the surface density of the induced charge on plane-parallel plates written as infinite series. However, the article was devoted to the method of conformal transformation of the initial problem to a simpler one, which makes it possible to obtain analytical expressions for the mentioned quantities. In the present article, I would like to clarify the situation and outline the advantage of the conformal transformation method taking into account the axial symmetry of the problem as compared to solving the problem in the form of infinite series.

The paper examines experimentally the dependence of gas temperature in a glow discharge on gas-dynamic flow parameters and discharge energy parameters. The gas pressure P and its flow rate G in the discharge chamber varied from 2.5 to 5.5 kPa and from 0 to 0.035 g/s, respectively. The discharge current strength I and the power input N to the discharge also ranged from 30 to 80 mA and from 30 to 80 W. The gas temperature was measured by the thermocouple method at six points of the discharge gap, which also made it possible to estimate the change in gas temperature along the axis of the cylindrical channel and along its radius. At low gas consumption, the discharge was found to be axisymmetric and fill the entire volume of the discharge gap. As the current and discharge power increased, the gas temperature increased approximately linearly with an average rate of 5 K/W. With increasing air flow rate G from 0.017 to 0.035 g/s, the discharge rearranged from a bulk shape to a cord shape, and the temperature field of the discharge changed significantly: in the center of the discharge, the temperature decreased sharply and practically did not change with increasing discharge power, while near the discharge localization, the gas temperature increased linearly with increasing power at an average rate of 3 K/W.

A simulation technique for the RF signal propagation in a traveling wave accelerating structure by the method of equivalent circuits is described. Calculations have been carried out for the propagation of a signal with a frequency of 2856 MHz in an accelerating structure with a constant gradient consisting of 102 cells. The possibility of changing the energy of an accelerated beam through rotation of the signal phase within a long pulse is shown.

Antioxidant cytoprotective properties of mexidol have been studied under the influence of argon and helium gas-discharge cold plasma of atmospheric pressure on Paramecium caudatum cell culture. It has been shown that mexidol exhibits strong antioxidant properties and practically completely eliminates the negative effects of oxidative stress, retaining almost 100% of the initial number of cells. The data obtained demonstrate a wide range of behavioral responses of cells of Paramecium caudatum, which confirms their practical value as model objects for pharmacological and toxicological studies, and the use of gas-discharge cold plasma makes it possible to exclude the direct oxidative effect of hydrogen peroxide (the standard model of oxidative stress) on the studied drugs and to increase the reliability of toxicological studies.

A physical and mathematical model of a magnetoplasma compressor (MPC) is presented. The electrical characteristics and energy-power modes of MPC discharges in gases are analyzed. The radiation and plasmadynamic structures and spectral-brightness characteristics of MPC discharges are determined. Various quasi-stationary spatial distributions of plasma parameters are calculated for various heating modes (ohmic, transient, and plasmadynamic). The results of computer simulation of a plasmadynamic discharge in a magnetoplasma compressor are discussed.

The work is devoted to the dosimetric studies of a low-intensity beam for the implementation of proton radiography on the proton therapy complex Prometeus. In contrast to therapy, radiography using proton beams requires low particle fluxes, less than 1 × 10⁶ protons/(s cm²). The controlled uniform extraction of beams of such intensity at therapeutic accelerators is a significant challenge, and it requires the development of innovative approaches. This study is part of a series of studies on the Russian medical proton synchrotron for implementing the extraction of low-intensity beams. The paper presents data on the key parameter of the extracted beam—the absorbed dose—when performing radiographic plans with a scanning beam. It also provides a quantitative analysis based on computer simulation of the spatial characteristics of proton images obtained using the extracted beam parameters.

The paper presents the results of experiments on studying laser-stimulated heating in the near-infrared region of the spectrum of aqueous suspensions of nanoparticles (NPs) based on silicon (Si and Si–Fe NPs) and titanium nitride (TiN NPs) by a continuous laser with a wavelength of 808 nm and a power of 0.36 mW. Temperature profiles were obtained, and the heating rate and photothermal conversion efficiency were determined for each sample at a concentration of 1 mg/mL. The conversion efficiencies for the studied aqueous suspensions of TiN, Si–Fe, and Si NPs were 90, 36 and 10%, respectively. The results obtained show that TiN and Si–Fe NPs can be used as photoagents to control local photohyperthermia in biomedicine.

A detailed analysis of regimes of operation of Johann spectrometers is presented for the point-like and extended sources. It is recommended to be carried out for the experiments on determination of plasma parameters from relative intensities of X-ray lines. The analysis is aimed at improving X-ray spectroscopy methods.