A description is given of simulation experiments of the interaction of lunar dust with the surface of solar panels. The experiments are based on the creation of a dust plasma cloud by exposure of a substance simulating lunar dust to the radiation from a powerful pulse gyrotron. This approach has been tested using a lunar regolith simulant. An analysis is presented of the results of precipitation of charged regolith particles on solar panels of various types and variation in their efficiency.

An experimental study of self-organization processes that arise during evaporation of droplets of a colloidal solution of nanocarbon in ethanol from the surface of quartz glass is presented. The influence of the distilled-water content in the colloidal solution and the temperature gradient on the substrate on the distribution of nanoparticles and their agglomerates over the contact area of the drop with the surface are discussed. The evaporation of a multicomponent droplet is examined and described from the viewpoint of mass transfer by identifying the characteristic mechanisms of fluid motion in the droplet as the main cause of motion of nanocarbon nanoparticles. A detailed analysis of nanolayers and nanoparticle agglomerates deposited by droplet coating is performed, and the optimal conditions in terms of the substrate temperature and the pure-water content are determined, under which the most uniform spatial distribution of nanoparticles over the contact area of the droplet with the substrate is observed, as well as additional regimes with spatially uniform distributions of nanoparticle agglomerates (more than 10 μm).

The radiation of signal by the plasma asymmetrical dipole antenna is studied for two methods of its excitation. Earlier, it was shown that the 2nd and 3rd harmonics of the input signal frequency in the radiation spectrum of the plasma antenna are 10–20 dB stronger than those of a metal antenna with the same geometry. In this work, we study experimentally and by computer simulations the effect of the method of excitation of the plasma asymmetrical dipole antenna on the spectral characteristics of the signal that it radiates. For the two excitation methods of the antenna, through an electrode and through a coaxial coupler, it was shown that the strength of the signal components at the frequency of the radiated signal and its multiple harmonics is different. The introduction of the coaxial coupler in the antenna excitation scheme allowed us to improve the coupling at the input signal frequency and decrease its components at the 2nd and 3rd harmonics. For the plasma antenna with the coaxial coupler, the difference between the 1st and 2nd harmonics was increased by almost 6 dB, and between the 1st and the 3rd ones by almost 20 dB compared to the antenna excitation scheme through the electrode.

We study electrical parameters of nanosecond spark discharges generated by a piezoelectric transformer. The spark is generated in a 3 mm long air gap between the output (high-voltage) end of the piezoelectric transformer and an ungrounded metal cylinder (h = 12.3 mm and D = 8.6 mm). The active power consumed by the discharges (average over the period) and the energy input are estimated, a current oscillogram is obtained, and the air gap voltage versus time is plotted.

We report an experimental study of self-assembly processes that occur during the evaporation of a colloidal solution of nanostructured carbon in ethanol during vertical deposition of nanoparticles on a quartz substrate. The effect of the pulling speed and the angle at which the substrate is fixed on the structure of the carbon coatings formed on the surface of the samples is discussed. The fabricated nanocarbon films are analyzed in detail. Optimal conditions for the formation of the most uniform spatial distribution of nanoparticles and their agglomerates over the surface of quartz substrates are determined.

We present a description of a plasma-chemical facility designed for synthesis of micro- and nanoparticles using the radiation of a high-power gyrotron. The facility has been developed at the Plasma Physics Division of A.M.Prokhorov General Physics Institute of the Russian Academy of Sciences. The facility includes a plasma-chemical reactor, a gyrotron unit, an in-line calorimeter, a diagnostic system, which ensures video and spectroscopic measurements, balance measurements of the microwave radiation, and thermal imagery measurements, a chemical unit for specimen preparation and analysis of synthesis products, an electronic logging unit, and a specimen labeling system for organization and storage of a large amount of experimental data and specimens.

As a result of interaction under normal conditions in an air atmosphere of a microwave pulse of a gyrotron with a mixture of Al/Al2O3 powders, ceramic particles of morphology microprocesses are synthesized. A variant of a multi-stage process for the development of physical and chemical processes in a reactor, taking into account ignition. After the end of the microwave pulse, a cloud is observed consisting of hot aluminum oxide particles and burning aluminum particles. A certain influence of the combustion process of aluminum particles on the products of plasma-chemical synthesis. The paper also determines the average velocity of particles from the powder mixture, the burning time of aluminum particles, the surface temperature of the particles of the powder mixture, and the temperature of the gaseous medium in the upper part of the plasma-chemical reactor.

— The results of the first experiments on the preparation of silicon carbide nanopowders using a surface microwave discharge in a mixture of monosilane and methane are presented. It is shown that nanosized crystalline silicon carbide is formed as the main product of the reactions, and nanosized crystalline silicon is formed as the by-product. The average particle size is 13 nm.

The features of the experimental operation of the Sinus 550-80 plasma relativistic microwave generator (PRG) at different plasma densities are considered. Two plasma density values are considered, at which the central frequencies of the PRG output microwave radiation are 5.1 and 11.5 GHz. Numerical simulation demonstrates a decrease in the plasma electron density as a result of the action of a relativistic electron beam (REB) charge during the Cherenkov interaction and the appearance of an “ion background” during the PRG pulse. At low plasma densities, this can lead to a change in microwave generation conditions accompanied by a change in the broadband radiation to the narrowband one and a decrease in the radiation power. At the same time, at high plasma densities, when the microwave radiation is generated at high frequencies, the average amplitude of the electric field of the wave almost does not change during the REB pulse, and the radiation remains broadband. The analysis of the experimental and numerical simulation results is supported by estimates of the linear theory, which proves that the PRG works more stably at higher plasma density values.

Представлены экспериментальные результаты по осаждению заряженных частиц, имитирующих левитирующую пыль реголита (пылевую плазму) на Луне, на металлические пластины. Эксперимент основан на аналогии физико-химических процессов, развивающихся в реголите при микроволновом разряде, возбуждаемом излучением мощного гиротрона, в лабораторном эксперименте в порошке реголита (лунной пыли) с процессами, которые происходят на Луне при бомбардировке ее поверхности микрометеоритами. Исследуется воздействие левитирующего облака пыли на пластины из молибдена и тантала. Результаты сравниваются с экспериментом по воздействию пыли на пластины из нержавеющей стали. Показано, что на пластины металлов (размер которых составляет 10 мм × 40 мм) осаждаются частицы пыли в виде сфероидов различной величины. Распределение этих частиц по размерам и химический состав покрытия соответствовал лунному реголиту. Установлено, что на равномерность осаждения пыли возможно повлиять, произведя предварительную обработку пластин металлов с помощью низкотемпературной плазмы прямого пьезоразряда. Продемонстрировано, что полученная в лабораторных условиях левитирующая пыль (ансамбли заряженных частиц реголита) может быть использована для имитационных экспериментов для изучения модификации поверхности разных материалов и разработки способов очистки космической техники в условиях лунных экспедиций.

The pulse-periodic operation regime of a plasma relativistic microwave generator is considered. The reasons for the increase of average frequency of the output microwave radiation in a pulse train created in the same conditions of initial plasma generation are analyzed. The effect of solid body erosion that occurs due to the interaction of the relativistic electron beam with the collector surface on the output microwave radiation is studied. The analysis of experimental data is accompanied by numerical simulations by the electromagnetic PIC code KARAT. It is shown that increasing the amount of mater extracted from the surface of the collector during erosion leads not only to an increase of the plasma density, but it can also lead to qualitative changes of the parameters of the output radiation, which are caused by the change of microwave generation regime. In particular, the generation of an ion background that is inhomogeneous in the radial direction caused a change of conditions of plasma–beam interaction during the second half of the pulse and a change of the spectral density of radiation at the main frequency. Numerical simulations were used to demonstrate this for two different admixtures, iron and graphite.

The commissioning of the MIG-3 gyrotron complex at the L-2M stellarator has made it possible to reach a record power density input into plasma of 3.4 MW/m3 during the ECR heating of the plasma. This power input, however, resulted in noisy Doppler reflectometry signals (with a high-amplitude component at the gyrotron working frequency of 75.3 GHz), which could not be processed and analyzed. We modernized the filtering system of the Doppler reflectometry diagnostics, which had consisted of two pin-type band stop waveguide filters. Another pin-type filter was added to the filter system and a new compact bandstop filter was designed based on the Fabry-Perot resonator (BFFPR) to provide high suppression at the frequency of 75.3 GHz and low attenuation at the 30–40 GHz diagnostic frequency. We optimized the cavity length of the filter and calculated the characteristics of filters with different numbers of resonators by using numerical simulations. The filter layout was designed, and its characteristics were measured. The results of experimental measurements and numerical simulations have a good match. The redesigned filters were used to suppress the noise from the MIG-3 gyrotron complex.

In this paper, we study a compact source of low-temperature cold atmospheric plasma based on a piezoelectric transformer used as a high-voltage source. This device can produce a direct piezo-discharge in the atmosphere, a classical dielectric barrier discharge, and a discharge in a noble gas flow. We have estimated the rotational and vibrational temperatures of the N2 ions and the electron temperature in the discharge from the emission spectra for different modes of source operation. When the source operated with loads of two types (metal and liquid loads), the electric field strength distribution near the discharge gap was measured with a probe operating on the basis of the Pockels effect. The possibility of application of this device for electromagnetic field impact on biological objects and plasma-activated media is discussed.

Efficiency of the transmission of high-frequency signals by semiconductor plasma antennas based on Ge and Si single crystals with surface nonequilibrium electron-hole plasma generated by laser diode radiation has been experimentally studied. Dependences of the amplitude of a radiated 6- to 7.5-GHz microwave signal on the laser power and size of the laser-irradiated region on the semiconductor transmitting dipole antenna are determined. It is shown that a more than tenfold increase can be achieved in the efficiency of useful signal transmission by the plasma antenna formed in Ge crystals.

Time evolution of the parameters of output radiation of a plasma relativistic microwave oscillator (PRMO) based on the Sinus 550-80 accelerator during a single relativistic electron beam (REB) pulse was studied experimentally. Analysis of the experimental data was accompanied by numerical simulations under conditions close to the experimental ones. It is shown that qualitative changes in the parameters of the PRMO output radiation are associated with a change in the generation mode. The first half of the REB pulse is characterized by the maximum output radiation power and a broadband spectrum consisting of a great number of harmonics. The nonlinear beam–plasma interaction limits the growth of the field amplitude, decreases the number of plasma electrons, and leads to the emergence of longitudinal plasma inhomogeneity. The appearance of an ion background in the drift tube volume and the formation of a radially nonuniform plasma waveguide alter the conditions of beam–plasma interaction in the second half of the pulse. The second half of the REB pulse is characterized by a decrease in the output microwave power and the narrowing of the generation frequency band. Spectral analysis demonstrates preservation of a stable narrow spectral component throughout the microwave pulse.