Some aspects determining the electrical strength of the accelerating gap in a fore-vacuum-pressure plasma-cathode electron beam source utilizing helium and argon as the working gas were explored. Penetration of plasma into the accelerating gap is the cause of breakdown. We find that gap breakdown occurs at larger emission hole diameter and at higher plasma density in helium than in argon. The greater stability of the plasma boundary in helium is explained by the observed greater anode potential drop and consequently greater sheath thickness.

Using MWS CST software, the diffraction of a normally incident TEM p-polarized wave on a graphene nanoribbon metasurface with combined electric and magnetic control is simulated with a bias magnetic field applied perpendicularly to the graphene. The frequency dependences of the modulus of the transmission coefficient of the p-polarized TEM wave through graphene nanoribbon-based metasurfaces are calculated for different values of the Fermi level EF and the induction В0 of a bias magnetic field in the THz and far IR frequency ranges. It is shown that the frequency modulation index and the maximum values of the change in the transmission coefficient through the graphene metasurface increase with an increase in the magnetic induction В0 of the applied external bias magnetic field and with a decrease in the Fermi level EF in the optimal interval of EF variation (0.2–0.35 eV).

The coupling coefficients of disk-shaped dielectric resonators interacting through a two-conductors stripline resonator placed in the rectangular diaphragm of a metallic case have been studied. It has been found that the capacitive interaction of the resonators changes to inductive when the eigenfrequency of the stripline resonator is lower than those of dielectric resonators. This feature makes it possible to design small-size multicavity bandpass filters with additional capacitive and inductive couplings, which are expected to offer a high selectivity and a small spread of the group delay time in the passband. Using the electrodynamic analysis of a 3D model, a small-size 12th-order filter with center frequency f0 = 3.925 GHz of the 45-MHz-wide passband has been synthesized. The width of the passband was measured at a level of 1 dB from the minimal loss level. In the designed filter, a two-conductors stripline resonator is used to provide differing-in-sign additional couplings between disk-shaped resonators and couple feed lines at the input and output. This improves the filter manufacturability and raises the mechanical strength of the device. The characteristics of the filter confirm that the proposed design is promising for creating small-size frequency-selective devices for space communication.

This article is devoted to the development of modeling methods for the extremal propagation of an induced excitation in network communities. The problem of analysis of information space perturbation is considered as a form of an ordered chain reaction, which, however, has an aleatoric indeterminacy component at the key stage of the event branching process. In this conception, the account groups excited by fake information play the role of short-term emitters of a hype flow, which is analogous to decaying nuclei that have become unstable after the neutron capture. Network tsunamis aimed at spreading a distorted projection of an actual situation are similar in the activation and decay principles to processes in reactors in controlled nuclear decay. A targeted aggressive information leak induces the excitation of network nodes, which is analogous to the emission of a neutron flux. Predictions must take into account the fact that social communication segments differ in the degree of communication between the groups. The difference is observed in the resistance to an attack and the response to the action, which can be classified as positive, negative, or neutral. It is proposed that the properties of the hype flow after the leak of the “hot content” in a heterogeneous field be investigated as a type of chain reactions during the capture of particles. The network social medium is flexibly structured and separated into a large number of clusters. The communications between the clusters can be represented in the form of redefinable hypergraphs with random arcs. There appears the phenomenon of a political group polarization wave. The information attack concept takes into account the fact that the content in social platforms is controlled and admissible activity is moderated. The emission of the content for a subsequent separation of already segmented groups is connected with the factors of the information source and social-information communication channels. Any from the variety of factors can facilitate the enhancement or suppression of the group polarization. Dynamic effects of pulsed activity of information flow include natural activity (noise) in the information space as well as the emission of the content by organized means (botnet) for inducing a chain reaction of agitation waves and for manipulating the behavior. Wave phenomena of formation of chains of propagation and mutual pulsed activation/suppression of the resistivity of neutral participants are observed sporadically. A small perturbation is suddenly transformed into an avalanche of destructive emotions and mutual hatred like the nuclear decay energy. It is shown that the scenarios of botnet information attacks on network communities differ in dynamics from spontaneous phenomena of hype bursts by a series of regular spurious short peaks. Chain reactions and crises of the domino effect type are of variative and scenario nature. The processes without a predetermined choice from several courses are known as aleatoric processes. The reactions based on the principle of a falling domino set begin when the transformation of one group of reagents stimulate the reaction of another bound group of reagents in the presence of inducing catalysts (botnet in the network). The hype energy in a cluster is critically accumulated, which rapidly leads to a chain propagation of a wave; however, the passage of such a wave is unstable. It is proposed that the network tsunamic model be constructed using the method of an aleatoric chain with a probabilistic choice from the forms of logically coupled wave equations of the hype decay and activation modes.

Ground-based imaging atmospheric Cherenkov telescopes (IACT) with a single reflector are used to study cosmic gamma-ray sources. These telescopes capture images of gamma/proton-initiated Cherenkov showers. Their performance can however be limited by aberrations caused by the single reflector design. Recent studies have demonstrated that the Schwarzschild-Couder Telescope (SCT), which uses a dual-mirror aspheric-reflecting surface, can significantly reduce these aberrations. In addition to minimizing aberrations, the SCT also improves the angular resolution and field of view of the telescope. Using an in-house developed Python based code; we conducted ray-tracing feasibility studies for Hanle altitude for simulation a 4 m class SCT. Using CORSIKA simulations, we also estimated the energy threshold for such a telescope at Hanle altitude. The optical sizes of the primary and secondary mirrors, along with other optical parameters, were optimized using the Zemax optic studio.

The contaminant distribution on the composite insulator has acted a prominent impact on the pollution flashover voltage, and the accumulated pollution caused the insulator to discharge, resulting in a depressurization operation and threatening the safety of power system. In this study, by selecting a series of the composite insulators on the arresters in the direct current (DC) field area, the pollution levels of the insulators at different positions and the different surfaces of the same group of the insulators were regularly collected and analyzed. Combined with the content variation and component characteristics of atmospheric particle pollutants, the contaminant degree of the composite insulators was correlated with the characteristics of atmospheric particle pollutants, and the contaminant accumulation characteristics of composite insulators in DC field environments were sufficiently clarified. The results revealed that the equivalent salt density and gray density of the lower surface of the insulator were larger than those of the upper surface under normal conditions. The effect of atmospheric precipitation on the insulator dirt was relatively weak, and the composition and content of the dirt between the upper and lower surfaces of the same insulator as well as insulators with different columns were essentially the same. A negative correlation was existed between the particle size of the insulator dirt and the equivalent salt density and equivalent gray density of the insulator. This work illustrates the contaminant accumulation characteristics of composite insulators in the DC field, and provides a scientific basis for ensuring the safe operation of power system.

A new thin-film transistor (TFT) structure based on hydrogenated amorphous silicon-germanium (a-SiGe:H) is proposed and analyzed, incorporating a double-layer gate dielectric. Silvaco TCAD simulations are employed to evaluate the electrical performance of a conventional single-layer silicon dioxide (SiO2) dielectric compared to a novel bi-layer configuration combining hafnium dioxide (HfO2) and SiO2. The bi-layer design leverages the high permittivity of HfO2 to enhance gate control while maintaining excellent interface quality through the inclusion of a thin interfacial SiO2 layer. This structure effectively addresses common limitations of high-κ dielectrics, such as interface traps and gate leakage. Simulation results demonstrate that the proposed bi-layer dielectric significantly improves device characteristics, reducing the threshold voltage from 0.458 to 0.130 V, increasing the ON-state current from 1.85 × 10−7 to 3.24 × 10−5 A, and enhancing the ON/OFF current ratio from 1.71 × 105 to 4.68 × 106, with only a modest increase in subthreshold swing. Electric field and energy band analyses further confirm improved electrostatic control and reduced leakage current. These findings underscore the potential of the HfO2/SiO2 bi-layer dielectric structure for advancing the performance and scalability of a-SiGe:H TFTs in future electronic applications.

This study analyzed the changes occurring on the surfaces of tantalum carbide and oxide under the influence of helium ions. A technique was employed to determine the composition and thickness of layers formed through the sputtering process of binary targets under the influence of light ions. The data obtained was utilized to calculate the thicknesses of the modified layers and their respective compositions. The results indicated that the surface layers contain a lower proportion of the lighter component compared to the original material, which aligns with experimental observations.

A decomposition approach to mathematical modeling of nonlinear microwave devices with a distributed interaction has been developed based on descriptors of nonlinear autonomous blocks with Floquet channels (NABFs) in the form of nonlinear equations connecting the amplitudes of incident and reflected waves at the input cross section of Floquet channels. An iterative method for NABF decomposition has been developed based on the linearization of their descriptors. Using the computational algorithm developed by using the NABF method, the results of mathematical modeling of nonlinear diffraction and interaction of microwaves with nonlinear conducting and dielectric inclusions in striplines have been obtained.

Mathematical modeling of a plasma flow in coaxial channels with different outer electrode diameters is considered. A numerical model for determining the distribution of density, velocity, and magnetic fields in a channel is proposed based on the system of differential equations describing the mass, momentum, and energy conservation laws. Computational experiments show that depending on the outer electrode diameter, the location of the region of elevated density and velocity field changes, leading to variation of the time of emergence of the main mass of the plasma from the channel, as well as its value and velocity. For complex assessment of these parameters, the plasma momentum in the output cross section is calculated. The performed analysis demonstrates the existence of an optimal value of the outer electrode diameter, for which the maximal magnitude of the momentum is achieved.