bluuebunny/crossref_metadata_2025 huggingface dataset:
Two-component millicharged dark matter and the EDGES 21 cm signal *
Authors: Li Qiaodan , Liu Zuowei
Published: November 2021

We propose a two-component dark matter explanation to the EDGES 21 cm anomalous signal. The heavier dark matter component is long-lived, and its decay is primarily responsible for the relic abundance of the lighter dark matter, which is millicharged. To evade the constraints from CMB, underground dark matter direct detection, and XQC experiments, the lifetime of the heavier dark matter has to be larger than

, where

is the age of the universe. Our model provides a viable realization of the millicharged dark matter model to explain the EDGES 21 cm signal, since the minimal model in which the relic density is generated via thermal freeze-out has been ruled out by various constraints.
Recent results from deuterium experiments on the large helical device and their contribution to fusion reactor development
Authors: Osakabe Masaki , Takahashi Hiromi , Yamada Hiroshi , Tanaka Kenji , Kobayashi Tatsuya , Ida Katsumi , Ohdachi Satoshi , Varela Jacobo , Ogawa Kunihiro , Kobayashi Masahiro , Tsumori Katsuyoshi , Ikeda Katsunori , Masuzaki Suguru , Tanaka Masahiro , Nakata Motoki , Murakami Sadayoshi , Inagaki Shigeru , Mukai Kiyofumi , Sakamoto Mizuki , Nagasaki Kazunobu , Suzuki Yasuhiro , Isobe Mitsutaka , Morisaki Tomohiro , LHD Experiment Group the
Published: November 2021

In recent deuterium experiments on the large helical device (LHD), we succeeded in expanding the temperature domain to higher regions for both electron and ion temperatures. Suppression of the energetic particle driven resistive interchange mode (EIC) by a moderate electron temperature increase is a key technique to extend the high temperature domain of LHD plasmas. We found a clear isotope effect in the formation of the internal transport barrier in high temperature plasmas. A new technique to measure the hydrogen isotope fraction was developed in the LHD in order to investigate the behavior of the isotope mixing state. The technique revealed that the non-mixing and the mixing states of hydrogen isotopes can be realized in plasmas. In deuterium plasmas, we also succeeded in simultaneously realizing the formation of the edge transport barrier (ETB) and the divertor detachment. It is found that resonant magnetic perturbation plays an important role in the simultaneous formation of the ETB and the detachment. Contributions to fusion reactor development from the engineering point of view, i.e. negative-ion based neutral beam injector research and the mass balance study of tritium, are also discussed.
Multi-nucleon transfer reactions at ion catcher facilities - a new way to produce and study heavy neutron-rich nuclei
Authors: Dickel T. , Kankainen A. , Spătaru A. , Amanbayev D. , Beliuskina O. , Beck S. , Constantin P. , Benyamin D. , Geissel H. , Gröf L. , Hornung C. , Karpov A. V. , Mardor I. , Mu¨nzenberg G. , Nichita D. , Plaß W. R. , Pohjalainen I. , Purushothaman S. , Reponen M. , Rotaru A. , Saiko V.V. , Scheidenberger C. , Winfield J. S. , Zadvornaya A.
Published: November 2021

The production of very neutron-rich nuclides heavier than fission fragments is an ongoing experimental challenge. Multi-nucleon transfer reactions (MNT) have been suggested as a method to produce these nuclides. By thermalizing the reaction products in gas-filled stopping cells, we can deliver them as cooled high-quality beams to decay, laser and mass spectrometry experiments. High precision mass spectrometry will allow for the first time to universally and unambiguously identify the atomic and proton numbers of the ions produced in MNT reactions. In this way their ground and isomeric state properties can be studied in high-precision measurements. In experiments at IGISOL, Finland and at FRS Ion Catcher, Germany, we have done and will perform broadband measurements of the reaction products, with the aim to improve the understanding of the reaction mechanism and to determine the properties of the ground and isomeric states of the produced nuclides. First results and preparations for upcoming experiments are presented.
The Study of the 6Li(p,γ)7Be Reaction at LUNA
Authors: Piatti D.
Published: November 2021

The 6Li(p,γ)7Be reaction is mainly involved in two astrophysical scenarios: the primordial nucleosynthesis and 6Li consumption in pre-main and main sequence stars. A recent measurement of 6Li(p,γ)7Be reaction S-factor reported a resonance-like structure at Ecm = 195 keV, which has not been confirmed neither by other direct measurements nor by theoretical calculations.

A new experiment was performed at the Laboratory for Underground Nuclear Astrophysics (LUNA). The extremely low background environment allowed to measure the 6Li(p,γ)7Be cross section down to low energies with unprecedented sensitivity leading to clarify the existence of the claimed resonance. Details on the experimental setup and the preliminary results of the ongoing analysis are reported in this work.
40 year anniversary of the RADAN systems – compact pulsed power sources for various investigations
Authors: Shpak V G , Shunailov S A , Yalandin M I
Published: November 2021

This article includes a brief overview of the compact RADAN-series subgigawatt pulsed voltage sources and describes their capabilities in various electrophysical researches. We present the results obtained in the experiments at nano- and subnanosecond time scales on the formation of the voltage pulses with a special shape, electron beams emission in air gaps and by the cold cathodes in vacuum, as well as generation of electromagnetic radiation. Particular attention is paid to the promising application of the RADAN systems.
Subnanosecond breakdown of air-insulated coaxial line initiated by runaway electrons in the presence of a strong axial magnetic field
Authors: Mesyats G A , Osipenko E A , Sharypov K A , Shpak V G , Shunailov S A , Yalandin M I , Zubarev N M
Published: November 2021

Flow of runaway electrons (RAEs) propagating in a radial, air-filled gap of coaxial line (CL) changes the dynamics of breakdown in the field of traveling voltage pulse. However, despite the effect of RAEs, breakdown does not occur if subnanosecond pulse is less in duration and amplitude than some values. In this work, we study the influence of an external axial magnetic field (B
z) on the breakdown development. We demonstrate the transformation of the voltage pulse reflection from the ionized (breakdown) zone with changing B
z. Due to gyration of fast electrons in an applied magnetic field, the gas region ionized by RAEs does not reach the anode. The ionized bridge between the cathode and anode is gradually replaced by a near-cathode plasma layer representing a discrete, reflecting/absorbing inhomogeneity in the CL.
Measurement of the expansion velocity of the plasma high-current vacuum arc discharge
Authors: Zhigalin A S , Rousskikh A G , Oreshkin V I , Artyomov A P
Published: November 2021

In this work, we present experimental results on measuring the velocity of vacuum arc discharge plasma expansion. In the experiments, two designs of plasma guns were used. In the first version, the end of the arc discharge cathode was located below the plane of the anode, and the surface of the insulator separating them was parallel to the axis of symmetry of the plasma gun. In this design, the arc discharge plasma escapes the anode through a hole, the diameter of which coincides with the diameter of the cathode. In the second variant, the plane of the end face of the arc discharge cathode coincided with the plane of the anode, and the surface of the insulator separating them was located perpendicular to the axis of symmetry of the plasma gun. To obtain an image of plasma in the optical range, an FER-7 optical streak camera was used. Based on the results obtained, it can be concluded that the expansion velocity of the plasma of a high-current vacuum arc discharge does not depend on the design of the guns considered in this experiment.
Method of nanosecond triggering for a sealed-off pseudospark switch
Authors: Argunov G A , Landl N V , Korolev Y D , Frants O B , Geyman V G , Nekhoroshev V O
Published: November 2021

This paper describes a method of nanosecond triggering for the modified version of the commercially produced pseudospark switch TPI1-10k/50. The switch uses the trigger unit with the auxiliary glow discharge, and the proposed method is based on the principle of the current interception from the trigger unit to the grounded cathode cavity when the trigger pulse arrives. Different electric circuits for triggering have been investigated. In the circuit, where the so-called trigger resistor or the trigger inductance are available, in the whole range of hydrogen operating pressure, the range of the delay time of triggering corresponds to (80–100) ns with a jitter of (3–6) ns. In the electric circuit, where the trigger resistor is shortened, the delay time increases to about (110–140) ns. However, the jitter remains at approximately the same level.
Investigation of the near-surface matter density radial distribution in the skin explosion of cylindrical conductors
Authors: Datsko I M , Labetskaya N A , Vankevich V A
Published: November 2021

Investigations of the near-surface plasma formation process during skin explosion of cylindrical duralumin and copper conductors in rapidly increasing magnetic fields with their induction up to 500 T were carried out. The formation of plasma on the conductor surface was recorded by its glow in the visible range using a four-frame optical camera with an exposure time of each frame of 3 ns. The internal structure of the surface plasma, the assessment of the density of matter in it and its radial distribution were investigated using radiography pictures obtained by X-ray transmission with hv > 0.8 keV, which is formed at the “hot point” of the X-pinch. The dependences of the load substance density on its radius were determined and constructed from the obtained X-ray diffraction patterns at different points in time from the beginning of the current. So at 216 ns at a radius of 1.8 mm of a duralumin conductor with an initial radius of 1.485 mm, the density of the substance is estimated to be 0.0068 g/cm3.
Plasma channel dynamics in sub- and microsecond discharges in water
Authors: Zherlitsyn A A , Kozyrev A V , Semeniuk N S , Kondratiev S S , Alexeenko V M
Published: November 2021

Simulation results of a fast electric discharge and a strong acoustic wave in the water is performed. A theoretical model of a high-current plasma channel is presented. The model accounts for the energy ratio between the input electric power and the plasma channel conductivity, and adiabatic expansion mechanism of this channel in water. It allows you to calculate the dynamics of the expansion of the channel and the generation of a radially diverging acoustic wave. The presented study makes it possible to estimate the probable parameters of the phenomenon: when electric energy is introduced into the channel, its expansion velocity reaches 1.9 km/s, electrons number density in the plasma is up to 2·1020 cm−3. In this case, a strong acoustic wave propagates with a sonic speed (~ 1500 m/s), and the pressure amplitude in the vicinity of the plasma channel can reach 200 MPa. The stability of the model in relation to variations in the initial task parameters has been analyzed. The calculated data for the acoustic wave are in good agreement with the measurements.
The dynamics of the formation of initial stages of a transverse nanosecond discharge with an extended slot cathode in argon
Authors: Ashurbekov N A , Iminov K O , Zakaryaeva M Z , Shakhsinov G S , Rabadanov K M
Published: November 2021

The dynamics of the main characteristics of a limited nanosecond discharge in an extended slot cathode in argon at the values of the applied voltage to the electrodes close to the values of the voltages of the formation of a volume discharge are studied by numerical simulation. It is shown that this type of discharge can be used to create an extended dense plasma column with a high density of charged and excited particles. The analysis of the spatiotemporal dynamics of development of the electron density and the electron energy distribution function was carried out. It is shown that the high-energy electrons are formed at the front of the ionization wave due to the hollow-cathode effect.
Investigation of the aluminum electrodes erosion of a plasma gun during the operation of a high-current vacuum arc discharge
Authors: Artyomov A P , Rousskikh A G , Zhigalin A S , Rousskikh I A , Tyukavkin A G , Oreshkin V I
Published: November 2021

The aim of this work was to obtain magnitude quantitative estimates of the “closed-type” plasma gun aluminum electrodes erosion that occurs during the course of a high-current vacuum arc discharge. The experimental setup consisted of two current generators. The first generator capable of generating a current with an amplitude of up to 450 kA and a rise time of 500 ns was used as a current source for a plasma gun. The second one was used as an X-ray radiograph to visualize the object under study in the soft X-ray range (hv ≈ 0.5–3 keV). Quantitative distributions of the plasma linear mass are obtained both along the radius and along the length of the jet at different times. It was shown that the erosion properties of the electrode material are related to the current characteristics of the arc discharge current.
Determination of the voltage drop on a high-current vacuum arc discharge under conditions of a limited cross-section of the plasma flow
Authors: Rousskikh A G , Zhigalin A S , Oreshkin V I , Artyomov P
Published: November 2021

The work is devoted to the study of the high-current vacuum arc discharge characteristics under conditions of a limited cross-section of the plasma flow. The experiments were carried out on the IMRI-5 setup with a sinusoidal arc current amplitude of 300–350 kA and a rise time of 500 ns. Aluminum rods with diameters from 3 to 7 mm were used as a cathode. The plasma flow was formed in a channel whose diameter was equal to that of the cathode. The features of the formation of a plasma jet with various configurations of the used plasma gun are described. The electrophysical parameters of the arc discharge are presented. Theoretical estimates of the voltage drop across the high-current arc during the outflow of a plasma flow through holes with a limited diameter are provided.
Features of the electron avalanche formation process in a strongly inhomogeneous electric field under high overvoltages
Authors: Mamontov Yu I , Lisenkov V V
Published: November 2021

The simulation of the electron avalanche formation process in subnanosecond discharges of high pressure was carried out by means of the Monte-Carlo approach. The discharge gap under consideration was of the configuration “the finger-shaped cathode – the hemispherical anode”. The presence of a conic-shaped microprotrusion on a cathode surface was assumed. Such the electrode configuration provided the strongly inhomogeneous distribution of an electric field. A gas simulated was nitrogen at a pressure of 6 atm. An average electric field strength across the discharge gap was varied from 200 kV/cm up to 400 kV/cm. Microprotrusion height was varied from 0 um up to 30 um. The critical size and formation time of an electron avalanche were determined under various conditions simulated. The threshold electric field strength for electrons to transit into the continuous accelerating regime was calculated for various heights of the microprotrusion. The applicability of the non-self-consistent Monte-Carlo technique for the investigation of the runaway electron kinetics and the correct simulation of the runaway electron beam transport across the discharge gap was shown.
Some issues of the operation of plasma opening switches
Authors: Loginov S V
Published: November 2021

The paper analyzes some processes in a plasma opening switch with a conduction time of ~ 100 ns. Relations are derived for assessing the evolution of the ion current to its space charge-limited state and for estimating its maximum possible density. It is shown that the ion current density reaches its extremum before electron magnetization. Estimates for the electromagnetic energy delivered to the switch are also presented demonstrating that this energy is spent equally for creating a magnetic field in the plasma volume and for its ohmic heating.
Arc discharges operation in “elion” mode
Authors: Lopatin I V , Akhmadeev Yu H , Kovalsky S S , Ignatov D Yu
Published: November 2021

This paper presents the results of a study of an electron-ion-plasma alitization system using two arc plasma generators: a gas plasma generator based on a non-self-sustained arc discharge with a thermionic cathode “PINK” and a gas-metal plasma generator based on an arc discharge with a cathode spot. The system for discharges supplying and biasing of the samples assumes two sub-modes of operation: the ion cleaning sub-mode (ion sub-mode) and the sub-mode of samples electron heating (electron sub-mode), thus realizing the “elion” mode of the system operation. During the experiments, both the dependences of the average values of currents and voltages of discharges burning and probe measurements of the instantaneous plasma parameters values in both system operating sub-modes were investigated. It is shown, that the electron sub-mode of system operation is characterized by an increased burning voltage, which is caused by the formation of a positive anode drop of more than 10 V in the plasmas. Such a potential distribution in the discharges ensures effective heating of the samples by the discharges plasmas electron component.
Formation of plasma jets by a high-current discharge in metal vapor
Authors: Kokshenev V A , Kurmaev N E
Published: November 2021

Plasma sources based on high-current discharges (up to 20 kA) in vapors of an aluminum electrode material with initiation over the ceramic surface are investigated. Plasma flows with a divergence angle ≤ 20° and a pulse pressure of ~ 106 Pa were obtained. A design of a crowbar spark gap based on a plasma switch with developed plasma sources built into a magnetically insulated transmission line has been proposed and tested. A crowbar mode is implemented in the transmission line with a current of a mega-ampere level with a cut-off of the load circuit from the megajoule generator GIT-12 for the period of discharge of the Marx generator.
On the scaling laws for low-temperature plasmas at macro and micro scales
Authors: Fu Y , Wang X , Zheng B , Zhang P , Fan Q H , Verboncoeur J P
Published: November 2021

The theoretical background and historical development of the similarity theory during the past decades are reviewed. We demonstrate similar discharges in local and nonlocal kinetic regimes, taking the low-pressure capacitive radio frequency (rf) discharges and microdischarges as examples. By using fully kinetic particle-in-cell simulations, we verify the similarity law (SL) and show a violation of frequency scaling (f-scaling) in the low-pressure capacitive rf plasmas. The similarity relations for electron density and electron power absorption are confirmed in similar rf discharges. With only the driving frequency varied, the f-scaling for electron density is also validated, showing almost the same trend as the similarity scaling, across most of the frequency regime. However, violations of the f-scaling are observed at lower frequencies, which are found to be relevant to the electron heating mode transition from stochastic to Ohmic heating. The scaling characteristics have also been comprehensively studied for microdischarges with dimensions from hundreds to several microns, with transition from secondary electron dominated regime to field emission regime. Finally, practical applications of the similarity and scaling laws are summarized.
Study of radiative characteristics of a completed partial discharge
Authors: Yakovlev E A , Yugay V V , Zinovyev L A , Kashlev A R , Bezrukov V O
Published: November 2021

The work is devoted to the study of the optical and electrical characteristics of a completed partial discharge burning in the presence of an electrolyte (1.5% NaCl solution). The possibility of using optical sensors that are part of smartphones such as Xiaomi for research is shown. The dependence of the radiation intensity of the completed partial discharge on the value of the ballast resistance in the discharge circuit and the material of the grounded electrode (anode) is studied. The dependence of the breakdown voltage on the size of the discharge gap is also studied. It is shown that it has a nonlinear character at a significantly lower (up to 20 times) breakdown voltage in comparison with the case of the absence of an electrolyte.
Structure and properties of high-chromium steel irradiated with a pulsed electron beam and nitrided in a low-pressure gas discharge plasma
Authors: Ivanov Y , Petrikova E , Teresov A , Lykov S , Tolkachev O , Rygina M
Published: November 2021

Ion-plasma saturation of the surface of machine parts and mechanisms with gas elements (nitrogen, oxygen, carbon) is currently one of the most effective and widely used methods of surface hardening of metal products for various purposes in the industry of developed countries. The aim of this research is to develop a complex method for modifying the surface layer of AISI 310 steel, combining irradiation with an intense pulsed electron beam and subsequent nitriding in the plasma of a low-pressure gas discharge. As a result of the studies performed, the optimal parameters of modification were revealed, which make it possible to increase the hardness of the surface layer of steel by more than 11 times, relative to the hardness of the initial material, and 8 times, relative to the hardness of steel irradiated with a pulsed electron beam. In this case, the wear resistance of the steel exceeds the wear resistance of the original and irradiated material by more than 100 times. It has been established that the high strength and tribological properties of the modified steel are due to the formation of a two-phase (iron nitride and chromium nitride) layered nanoscale structure in the surface layer.
Surface modification of hypereutectic silumin subjected to a millisecond modulated electron beam treatment
Authors: Ashurova K T , Vorobyov M S , Petrikova E A , Ivanov Yu F , Moskvin P V , Rygina M E
Published: November 2021

In this work, using a unique feature of the “SOLO” electron source with a grid plasma cathode based on a low-pressure arc discharge, which consists in the possibility of controlled operation of the beam power during a pulse of submillisecond duration, and, accordingly, the rate of energy input into the sample surface, we investigated the modes irradiation of samples of hypereutectic silumin. The irradiation modes had the same energy density during the first 200 μs of the pulse, equal to 20 J/cm2 and differed in different durations of further maintaining the surface temperature at 600°C for a time of up to 1 ms. The results of tribological tests and methods of diffraction microscopy of the investigated defect structure, the elemental and phase composition, the morphology of the strengthening phases of the modified layer of the hypereutectic silumin samples are presented.
Deposition of Al2O3 coatings in Ar-O2 low-pressure discharge plasma under a high dissociation degree of O2
Authors: Tretnikov P V , Gavrilov N V , Kamenetskikh A S , Krivoshapko S V , Chukin A V
Published: November 2021

The deposition of Al2O3 coating with a corundum structure was done by anodic evaporation in a low-pressure arc with a self-heated hollow cathode. The conditions were created for increasing the energy of plasma electrons and a corresponding increase in the frequency of O2 dissociation by contraction of the discharge in the anode region. The discharge was maintained in a combined mode with a constant current (70 – 100 A), on which current pulses (100 μs, 1 kHz) with adjustable amplitude (up to 220 A) were superimposed. This mode ensured a change in the degree of O2 dissociation in the range of 0.3 – 0.5 at constant average discharge current and Al evaporation rate. It is shown that an increase in the degree of O2 dissociation leads to an increase in the rate of coating deposition by a factor of 1.3 and promotion of the preferred (300) orientation of crystallites. The effect is due to the features of the adsorption of molecular and atomic oxygen on the Al2O3.
Features of boriding die steel D5 by electron beams
Authors: Milonov A S , Dasheev D E , Smirnyagina N N , Lapina A E
Published: November 2021

The microstructure and microhardness of the boride layers formed on die D5 steel by the methods of electron beam borating in vacuum under continuous and impulsive bunch modes are investigated and confronted. Formed layers have a heterogeneous structure, which combines solid and plastic components resulting in the fragility reduction of boride layer.
Investigation of tungsten surface carbidization under plasma irradiation
Authors: Miniyazov A Z , Skakov M K , Tulenbergenov T R , Sokolov I A , Zhanbolatova G K , Bukina O S , Kozhahmetov Ye A
Published: November 2021

This paper presents the results of studying the formation of a carbide layer under various experimental conditions and the choice of the optimal parameters for carbidization of the tungsten surface under plasma irradiation in methane. Therefore, to assess the effect of the surface temperature of a tungsten sample during experimental work, the surface temperature of the sample was 1300-1700°C, and to assess the effect of the irradiation time, a range within 300-2400 s was selected. From the results of X-ray phase analysis of the surface of tungsten samples, concluded that the temperature of the sample surface and the duration of irradiation have a significant effect on the formation of a carbidized layer on the tungsten surface during plasma irradiation on plasma-beam installation.
Formation of catalytic and corrosion protective layers with use of ion beam assisted deposition of metals from vacuum arc discharge plasma
Authors: Poplavsky V V , Dorozhko A V , Matys V G
Published: November 2021

This paper presents a brief overview of our studies on the modification of materials using ion beam assisted deposition (IBAD) of metals from vacuum arc discharge plasma in order to form catalytically active and corrosion-resistant layers on the surface. Deposition of metals on different materials with simultaneous mixing of the deposited layer with the substrate surface by accelerated ions of the deposited metal was carried out in an experimental setup with a pulsed electric arc ion source. Catalytic and corrosion properties of the materials with the obtained layers were studied using electrochemical voltammetric measurements. The microstructure and composition of the resulting layers were studied using the SEM, EDX, WD-XRF, XPS, EBSD, and RBS methods.
Effect of power of ultrasound during micro-arc oxidation on morphology, elemental and phase composition of calcium phosphate coatings
Authors: Kazantseva E A , Komarova E G
Published: November 2021

The effect of the magnitude of the US (ultrasound) power applied during the MAO (micro arc oxidation) process on the morphology, elemental and phase composition of the CaP coatings was studied. The US at different power (50-200 W) applying during the MAO process led to the local destruction of the structure elements (spheres and pores) and local filling the pore spaces on the coating surface, and to the formation of local macro-pores inside the coatings near the substrate. Such morphological transformations led to the surface and structure heterogeneity of the coatings, increasing of the surface roughness from 3.0 to 4.5 μm and of the thickness from 50 to 60 μm. The US application at different power did not affect significantly the elemental composition of the coatings. At the same time, under applied US with power more than 100 W, the state of the coatings transformed from X-ray amorphous to the quasiamorphous with the small incorporation of crystalline phases of CaHPO4 and β-Ca2P2O7.
Computer simulation of temperature fields in the Cr (film)-Zr (substrate) system during pulsed electron-beam irradiation
Authors: Markov A B , Solovyov A V , Yakovlev E V , Pesterev E A , Petrov V I , Slobodyan M S
Published: November 2021

The paper presents the results of numerical simulation of the distribution of thermal fields during the formation of Cr-Zr surface alloy using a pulsed low-energy high-current electron beam (LEHCEB). The melting thresholds of the Cr-Zr system for different thicknesses of Cr films were calculated. The melting threshold of the Cr-Zr system increases linearly with increasing Cr film thickness. A linear regression dependency model of the melting threshold on the film thickness is proposed. Evaporation thresholds of the Cr-Zr system for different thicknesses of Cr films were calculated. The evaporation threshold of the Cr-Zr system increases linearly with increasing Cr film thickness. A linear regression dependency model of the evaporation threshold on the film thickness is proposed. The value of the LEHCEB energy density at which the lifetime of the film and substrate are equal is calculated. This value is a maximum value for the effective formation of Cr-Zr. A model of the LEHCEB energy density, at which the lifetime of the film and the substrate are equal, in the form of a third-degree polynomial is proposed.
Field electron emission from a nanostructured tungsten surface
Authors: Mikhailov P S , Muzyukin I L
Published: November 2021

In this paper, the electron emission from a nanostructured tungsten surface was investigated. A method for measuring an extremely low current (10−12 – 10−14 A) has been tested. It made possible to reduce the effect of the electric field on the sample surface and to minimize the probability of spontaneous breakdowns. For a detailed study of tungsten fuzz, a point tungsten anode (diameter 90 μm) was used. Field enhancement factor (β = 2000 – 3000) and effective emission area were calculated using the Fowler–Nordheim plots. The pre-breakdown current rise was studied. The emission current waveforms suggest the formation of several emission structures before the breakdown.
Plasma diagnostics during deposition of Zr-B-N coatings by magnetron sputtering of UHTC ceramic in DCMS and HIPIMS modes
Authors: Sytchenko A D , Kiryukhantsev-Korneev Ph V
Published: November 2021

In this work, plasma diagnostics during the deposition of Zr-B-N coatings by DCMS and HIPIMS methods were carried out, the structural characteristics and growth rates of the obtained coatings were investigated; the regularities of the influence of the working atmosphere on the composition of the plasma, as well as on the thickness and growth rate of the coatings are revealed. It was found that the introduction of nitrogen leads to a decrease in the concentration of Zr and B ions in the plasma, as a result of which the growth rate of the coatings decreases. Note that, when using the DCMS method, predominantly argon plasma is observed, while with HIPIMS, the plasma is characterized by a large number of metal ions.
Formation of a Cr-Zr surface alloy using a low-energy high-current electron beam
Authors: Markov A B , Yakovlev E V , Solovyov A V , Pesterev E A , Petrov V I , Slobodyan M S
Published: November 2021

The paper investigates the regularities of the formation of Cr-Zr surface alloy using a low-energy high-current electron beam (LEHCEB). The influence of the electron-beam processing parameters and the magnetron deposition parameters on the elemental composition of the formed Cr-Zr surface alloy is estimated. It is shown that, for all considered modes, there is a general tendency to a decrease in the chromium content in the surface alloy with an increase in the energy density or the LEHCEB processing pulse number. The thickness increasement of the chromium film applied in one cycle or the surface alloy total thickness increasement leads to an increase in the chromium content in the surface alloy. The LEHCEB processing parameters, namely the energy density and the number of pulses, have a greater effect on the chromium content during the formation of the Cr-Zr surface alloy in comparison to the magnetron sputtering parameters, namely the deposited film thickness and the formed surface alloy thickness. A linear regression model that describes the chromium content in the surface alloy depending on the film thickness, the surface alloy total thickness, the number of pulses and the pulse energy density is proposed.
Plasma electrolytic oxidation of Ti - W surface alloys synthetized by PVD-LEHCEB
Authors: Morini F , Franz S , Vicenzo A , Bestetti M
Published: November 2021

An innovative approach exploiting PVD-coupled Low-Energy High-Current Electron Beam (LEHCEB) and Plasma Electrolytic Oxidation (PEO) techniques were investigated to obtain photoactive TiO2-WO3mixed films. Ti-W surface alloys containing 14 at.% W were synthetized by PVD deposition of 185 nm thick W films onto Ti substrates, followed by LEHCEB alloying at 30 kV for 50 pulses. The obtained Ti-W surface alloys were treated by PEO in 1.5 M H2SO4 at constant cell voltage ranging from 100 to 200 V. The resulting mixed oxide films were investigated by XRD, SEM and EDS analysis. Photoelectrochemical properties were determined by linear sweep voltammetry in dark and under UV-C and UV-VIS irradiation.
Modification and optical degradation of thin multilayers under VUV/UV radiation from compressed plasma flows
Authors: Skriabin A S , Telekh V D , Pavlov A V , Chesnokov D A , Zhupanov V G , Novikov P A
Published: November 2021

Coaxial plasma accelerators are under consideration for generation of compressed plasma flows which are suitable for emitting of powerful broadband radiation (including the VUV/UV ranges). The using of different gases in a chamber allows to control the spectrum. For inert gases the upper value of energy is limited by its first ionization potential (for neon ≈ 21.55 eV). For air the maximum energy is limited by ≈ 6 eV. Such technical systems are suitable for studying of optical properties stability for thin multilayers and the other coatings. Such tests were fulfilled for bilayers based on HfO2/SiO2 pair on silica substrates which is stable for laser radiation in the visible and IR ranges. It was found that a single exposure of the radiation (for neon and air) caused a relative decline of the radiation durability in ≈ 1.03…1.14 times. Spectral measuring demonstrated that the maximum decline of transmission (up to of ≈ 3…4%) was detected for exposures in neon in the range of 320…450 nm.
Evaluation of magnetic properties of thin magneto-dielectric films deposited from beam plasma in medium vacuum
Authors: Zolotukhin D , Tyunkov A , Yushkov Y
Published: November 2021

By electron-beam evaporation of a solid state dielectrics (alumina ceramics) and a magnetic material (steel-3) in fore-vacuum, thin films of several μm, possessing both dielectric and magnetic properties, were deposited on a substrate. The work shows that the microstrip resonator method can be used to assess the presence of magnetic properties in films.
Two-stage PVD method for protective coating formation
Authors: Burdovitsin V A , Tyunkov A V , Yushkov Y G , Zolotukhin D B
Published: November 2021

The CVD methods are typically used for the formation of aluminum oxide coatings since aluminum oxide is a dielectric. The adhesion between the protective coating and the substrate material is normally improved by growing thin intermediate layers based on titanium oxides and nitrides. These intermediate layers are mainly formed using the PVD methods. In this paper, we propose a two-stage PVD method for forming a layered structure on the titanium substrate. The formation of intermediate layers was carried out by the magnetron method (first stage), and the main protective layer was deposited at the second stage using a fore-vacuum electron source. The dense beam plasma generated during the electron beam transport in a fore-vacuum gas medium compensates for the negative electrical charge accumulating on the surface of the aluminum oxide target and facilitates its effective evaporation. The electrical properties of the intermediate layers and the resulting layered coatings have been investigated, including the tangent of dielectric loss angle, the real and imaginary parts of the conductivity and the dielectric constant dependencies on frequency.
Effect of ultraviolet irradiation or diffuse discharge plasma on structure and surface electrical charge of micro-arc calcium phosphate coatings
Authors: Komarova E G , Kazantseva E A , Ripenko V S , Zharin A , Sharkeev Y P
Published: November 2021

The studies of the effect of ultraviolet (UV) irradiation and plasma of a runaway electron preionized diffuse discharge (REP DD) post-treatments on the surface structure and electrical charge of the micro-arc oxidation (MAO) coatings were performed. The UV irradiation and plasma treatment did not effect on the morphology, roughness and thickness of the MAO coatings. However, these post-treatments led to formation of the small fraction of the crystalline CaHPO4phase in the X-ray amorphous structure of the coatings. Moreover, the UV and REP DD plasma treatments increased the electrostatic potential (EP) negative values from –85 mV to –126 mV of the coatings in the following order: MAO < MAO/UV (for 5 min) < MAO/Plasma (with 10,000 pulses) < MAO/UV (for 20 min) < MAO/Plasma (with 80,000 pulses).
Lead evaporation by VUV radiation of various spectral ranges
Authors: Pavlov A V , Shchepanuk T S , Chebykin E O , Protasov Yu Yu , Telekh V D
Published: November 2021

The results of an experimental study of the plasma formed by the evaporation of the lead target in the field of powerful broadband VUV radiation are presented. A pulse light-erosion magnetoplasma compressor (MPC’s) discharge is used as a model source of VUV radiation. “Gas filtration” of radiation is used to control the spectral composition – the discharge takes place in pure inert gases: in argon at 200 torr and neon at 400 torr. This allows us to manage the spectral distribution of radiation energy and to limit the energy of quants which irradiate the lead target with the first ionization potential of buffer gas. Shadow photography, toeplergrathy, double exposure laser holographic interferometry are used for diagnostics. Experimentally established different distribution of parameters in the lead plasma depending on the spectral composition of the impact radiation (the composition of buffer gas). It is shown that when the energy of quants increases (above the lead second ionization potential), a more even heating of the plasma layer is realized.
High-entropy ZrTiCrNiCu coating
Authors: Yurov V M , Guchenko S A , Goncharenko V I , Oleshko V S
Published: November 2021

A magnetron target made of a high-entropy ZrTiCrNiCu alloy was synthesized by mechanical alloying methods followed by annealing in a vacuum furnace. Using this target, coatings were applied to steel samples with a thickness of 7-10 microns. After thermal annealing, the coatings were nanostructured. In terms of microhardness, the ZrTiCrNiCu coating is not inferior to, and in most cases exceeds the hardness of high-entropy equiatomic alloys. A high entropy coating has a low coefficient of friction. They turn out to be anti-friction, which, most likely, leads to energy savings. In this work, the surface energy, contact potential difference and work function of electrons for high-entropy coatings were determined for the first time.
Characterization of size and morphological composition of ablated nanoparticles of cerium dioxide after ultrasonic dispersion and centrifugation in aqueous solution
Authors: Mamontov V A , Yu Ryzhenkova A , Pugachevskii M A
Published: November 2021

The paper investigates the size and morphological composition of ablated cerium dioxide nanoparticles after ultrasonic dispersion at centrifugation speeds from 800 to 13400 rpm. A nanodispersed solution of cerium dioxide was deposited onto silicon substrates by the drop method. To characterize the size and morphological composition of cerium dioxide nanoparticles, methods of scanning electron and atomic microscopy were used, and X-ray phase analysis was performed. It was found that ablated cerium dioxide particles in an aqueous solution agglomerated and without centrifugation their average size was 162 nm, after centrifugation their average size varied from 86 nm to 142.5 nm. X-ray phase analysis showed that with an increase in the centrifuge speed, the size of the coherent scattering region decreases, which affects the effectiveness of antioxidant properties, for example, in the Fenton reaction.
Investigation of the effectiveness of antimicrobial treatment of poultry products by electrophysical methods
Authors: Vazirov R A , Sokovnin S Yu , Krivonogova A S , Isaeva A G
Published: November 2021

Improved methods of processing food and agricultural products make it possible to achieve an optimal effect at an acceptable level of its quality. In radiobiology, Methods of synergistic effect of two factors are widespread, in particular, the combination of treatment with ionizing radiation (IR), UV and plasma. The use of these methods in the production cycle can significantly improve processing efficiency. In the present work were treated combined feeds of ‘PK-5’ and ‘PK-6’ in order to investigate the synergistic effect of IR treatment and high pressure gas discharge plasma (HP GDP) radiation. As the source of IR was used the nanosecond electron beam (NEB) of the accelerator URT-1 (1 Mev). To create the HP GDP was used a high-voltage nanosecond generator GVI-150 (150 kV). The obtained results indicate the presence of a synergistic effect of the combined effects of plasma radiation and NEB.
Production of nanopowder of cerium (III) fluoride obtained by pulsed electron beam evaporation in vacuum
Authors: Ilves V G , Sokovnin S Y , Uimin M A
Published: November 2021

The method of pulsed electron beam evaporation in vacuum was first used to obtain CeF3 nanopowder (NP). During NP production, a high evaporation rate of the target (~ 7 g/h) and a higher percentage of NP collection (> 72%) were observed, both for fluoride and the previously obtained CeO2 oxide. It was found that the produced NP contains two crystalline phases: hexagonal CeF3 (95 wt.%, coherent scattering region ≈ 8 nm and [Ce-O-F] or [Ce-F]. The magnetic susceptibility of CeF3 nanoparticles (NPles) coincides with the susceptibility of micron particles, indicating the potential for using such NPles as a contrast agent for tomography. High specific surface area (CeO2-270 m2/g, CeF3 – 62 m2/g), large pore volume (0.35-0.11 cm3/g) allow the use of NPles as nanocontainers for drug delivery.
Preparation of iron oxide nanopowders by the radiation-chemical method
Authors: Balezin M E , Sokovnin S Y , Uimin M A
Published: November 2021

Various magnetic nanopowders of iron oxide were obtained using the radiation-chemical method when irradiated with a nanosecond electron beam. The main physical and chemical characteristics of the prepared nanopowders were studied, such as structure, porosity, thermal resistance and magnetic properties. It was found that, by selecting precursors and the composition of the solution, it is possible to control not only the textural properties and yield of the obtained nanopowders (by changing the dose and dose rate intensity of the electron beam), but also to obtain crystalline or amorphous nanopowders, on which their magnetic properties depend.
Investigation of biological and photocatalytic activity of multimodal nanopowders produced by pulsed electron beam evaporation in vacuum
Authors: Svetlova A , Yu Sokovnin S , Il’ves V G
Published: November 2021

Nanopowders doped with silver were produced by the method of pulsed electron beam evaporation. The pore sizes of the nanoparticles were 25-32 nm. Evaluation of photocatalytic and cytotoxic properties on cells was carried out. The prospects of using multimodal nanopowders as a photocatalytic agent, as well as for use in medicine, have been shown.
Application of a nanosecond corona discharge generator for electrical separation of ores
Authors: Korzhenevskiy S R , Komarskiy A A , Ponomarev A V , Chepusov A S , Krasniy O D
Published: November 2021

The use of a pulsed nanosecond voltage source in a corona separator was investigated. Measurements of the distribution of corona discharge current were obtained. The influence of the interelectrode distance on the distribution of the corona discharge current was investigated. Experiments with gold-bearing quartz-sulfide ore and ilmenite ore were carried out. A concentrate was obtained with a gold content of 48 g/t, a mass equal to 18.7% of the original, which corresponds to the extraction of 92% of gold. The titanium content of ilmenite was enriched from 2.87% to 18.1%.
Effect of pulsed soft X-ray radiation on the surface topography of some metals
Authors: Ligachev A E , Zhidkov M V , Sorokin S A , Potemkin G V , Kolobov Yu R
Published: November 2021

Effect of the pulsed soft X-ray fluxes (PSXF) on the surface topography of metals (Mg and Cu) has been investigated. Soft pulse X-ray irradiation (energy quanta of 0.1-1.0 keV) were carried out on a high-current MIG generator. The sample of magnesium was located at a distance of 10 cm from the X-ray source. Since the distance to the sample significantly exceeded the size of the X-ray beam, it can be assumed that the density of the X-ray radiation flow to the magnesium sample was uniform. The duration of the radiation pulse was 100 ns, and the radiation energy density in the pulse varied from 13 to 19 J/cm2. As a result of melting under the action of PSXF of the near-surface layer of metals and subsequent solidification, a wavy relief is formed on their surface. Defects in the form of craters, which usually occur after the impact of a powerful pulsed ion flow on metals, were not detected.
Investigation of the relative reactivity of volatile organic compounds in the air plasma of a pulsed corona discharge by the method of competing reactions
Authors: Filatov I E , Uvarin V V , Nikiforova E V , Kuznetsov D L
Published: November 2021

A method for determining the relative reactivity of volatile organic compounds (VOCs) with respect to the air plasma of a pulsed corona discharge is proposed. It is based on the use of specially selected mixtures of organic compounds. The approach is based on the method of competing reactions: all components of the mixture are in equal conditions, so the relative reactivity can be determined with high accuracy using the gas chromatography. The parameters of scaling processes are proposed – plasma chemical yield, relative reactivity, formal reagent as a set of plasma components. In this paper, using the example of a number of VOCs, we demonstrate the extended capabilities of the method using a special technique for processing experimental data. More accurate data on the relative reactivity of a number of VOCs of wide application have been obtained. It is proposed to use the energy yield of ozone as a criterion for the energy efficiency of a plasma chemical installation.
Synthesis of MAX-phases, structure and phase composition of modified layers on titanium alloy VT-1 as a result of electron-beam treatment
Authors: Lapina A E , Smirnyagina N N , Khaltanova V M
Published: November 2021

The article presents the results of research and identification of optimal conditions of formation of MAX-phases during treatment of titanium alloy VT-1 by an electron beam in a vacuum. The study of strength characteristics, thermal properties of composite layers was carried out. Thermodynamic study of phase equilibrium in Ti-Si-C and Ti-B-C systems under high vacuum conditions was carried out in order to optimize conditions of formation of functional layers. A mathematical model of the thermal impact of a powerful fast-moving electron beam on the surface of a titanium alloy has been developed VT-1 under the conditions of electron beam processing in the framework of the theory of thermal conductivity using the COMSOL Multiphysics software complex. The obtained numerical results made it possible to investigate the regularity of the distribution of temperatures and their rates of change depending on the action of the electron beam.