bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of the multichannel front-end chip for SiPM-based gamma detector
Authors: Chergui Ahmed C , Bychkova Oksana V , Popova Elena V , Stifutkin Alexey A
Published: November 2019

A prototype of a multichannel application specific integrated circuit(ASIC)analog front-end chip was recently developed at the Department of Microelectronics in MEPhI for SiPM-based applications[1]. The chip designed as an analog front-end for the detectors using scintillation crystals NaI(Tl) or CsI(Tl) coupled with a SiPM photosensor.The chip can be used to build multichannel systems in such fields as nuclear science, medical imaging and homeland security.
Machine learning approach to pulse shape discrimination in liquid noble gas detectors
Authors: Grobov A
Published: November 2019

Study of the event classification in liquid noble gas detectors is presented. The discrimination between different events usually done by prompt light fraction. To tackle this task we adopt the neural net classifier and use pulse shape as an input feature. The main difficulty comes from low-energy events that are difficult to separate. This is important because these events provide a background for dark matter searches. We find that neural networks are suitable for this task.
The measurement of liquid scintillator nonlinear response and intrinsic energy resolution
Authors: Formozov A
Published: November 2019

For Jiangmen Underground Neutrino Observatory the requirements < 1 % energy scale uncertainty and 3 % at 1 MeV energy resolution are crucial in order to determine neutrino mass hierarchy. In this study, we focus on non-linearity due to ionization quenching and intrinsic energy resolution of the liquid scintillator. To measure them a small-scale laboratory setup was developed and the measurement of Birk’s quenching constant kB = 0.0196 ± 0.0019 (stat) ± 0.0030 (syst) cm/MeV was provided. With the assumption of negligible light collection term, intrinsic energy resolution term was determined: vint
(50keV) ≈ 0.02 ± 0.005. This value is comparable with the statistical term of JUNO, therefore the effect could significantly contribute into the total energy resolution at this energy. Further studies should be directed toward accurate estimation of light collection effects.
Calibration of the ALICE PHOS calorimeter
Authors: Blau Dmitry
Published: November 2019

The procedure for the energy calibration of the high granularity electromagnetic calorimeter PHOS of the ALICE experiment is presented. The methods used to perform the relative gain calibration, to estimate the geometrical alignment and the corresponding correction of the absolute energy scale, to evaluate the non-linearity correction coefficients and finally, to calculate the time-dependent calibration corrections, are discussed and illustrated by the PHOS performance in proton-proton (pp) collisions at

s

=
13

TeV

. After applying all corrections, the widths of π0 and η meson peaks at p
T > 1.7 GeV/c σ
π
0 = 4.51 ± 0.03 MeV/c2 and ση
= 15.3 ± 1.0 MeV/c2, respectively, were achieved.
The Dark Matter search at KamLAND
Authors: Kozlov A. , Chernyak D. , Takemoto Y. , Fushimi K. , Imagawa K. , Yasuda K. , Ejiri H. , Hazama R. , Ikeda H. , Inoue K. , Yoshida S. , Etezov R. A. , Gavrilyuk Yu. M. , Kazalov V. V. , Kuzminov V. V. , Panasenko S. I.
Published: November 2019

Recent data from the DAMA/LIBRA phase-2 confirmed detection of a signal with independent Dark Matter (DM) annual modulation signature at a 12.9σCL. Our attempts to verify the DAMA/LIBRA DM observation claim led to construction of underground clean rooms at the KamLAND site and specialized laboratory for production of NaI(Tl) detectors. Current status of these facilities, methods used to grow ultra-low background NaI(Tl) crystals, and radio-purity of the latest NaI(Tl) DM detector prototype are discussed.
Characterization of a scintillator tile equipped with SiPMs for future cosmic-ray space experiments
Authors: Di Venere L , De La Torre Luque P , Gargano F , Giordano F , Fusco P , Loparco F , Loporchio S , Mazziotta M N , Serini D
Published: November 2019

Current gamma-ray and cosmic-ray satellite experiments employ plastic scintillators to discriminate charged and neutral particles and to identify nuclei. Scintillators are commonly read out using the classical photomultiplier tubes (PMTs). Recent measurements and R& D projects are demonstrating that Silicon Photomultipliers (SiPMs) are suitable for the detection of fast light signals with resolution up to the single photoelectron, with a lower power consumption. For these reasons, next generation missions are planning to replace PMTs with SiPMs. We tested a prototype plastic scintillator tile, equipped with a set of SiPMs and studied its response to a beam of electrons and pions at CERN. We used Near Ultraviolet (NUV) SiPMs of 1x1 mm2 and 4x4 mm2 area, placed along the edges of the tile. The tile was irradiated in different positions in order to study the dependence of the collected light on the impact point of the beam particles. We also varied the energy of the beam in order to study how this parameter affects the amount of collected light.
A four-layer gaseous detector allowing to measure the energy of charged particles
Authors: Potashev S , Burmistrov Yu , Zuyev S , Karaevsky S , Konobeevski E , Razin V , Afonin A
Published: November 2019

A four-layer gas detector for electrons and other charged particles is developed. A charged particle passing through a thin window produces ionization in four consecutive gas gaps separated by absorbers. The gas gain about of 104 allows one to determine four signal amplitudes under the control of any combination of these signals. Simultaneous measurement of the ionization losses of the particle in the successive layers of the detector makes it possible to determine the energy of the passing particle.
The principles of neutrino source creation on the base of lithium. The variants of realization (review)
Authors: Lyashuk V I , Lutostansky Yu S
Published: November 2019

It is discussed the conception of antineutrino-electron-source-creation on the base of 7Li isotope and the principal requirements for realization including the possible schemes isotope purity, perspective substances, efficiency. The source can operate in the static and dynamic regimes, in the tandem scheme of the accelerator plus lithium blanket. It was considered the advantages ensured by lithium antineutrino source for neutrino experiments.
Distributions of the charged particles in the electromagnetic showers initiated by 5-1000 GeV electrons in Fe, W and Pb
Authors: Denisov S P , Goryachev V N
Published: November 2019

The results of calculations of the charged particles multiplicity, energy, radial and time distributions in the electromagnetic showers initiated by electrons with energies from 5 to 1000 GeV in Fe, W and Pb are presented. It is shown that the multiplicity distributions are well fitted by the inverse sum of two exponents in a wide range of energy and lead depth. The shapes of energy and radial distributions at the shower maximum weakly depend on the electron energy. Radial distributions for all materials studied are similar if radius is expressed in g/cm2. The time spread of the charged particles at the shower maximum turned out to be in the picosecond range.
The adaptive-modular technique for pre-project simulation the transportation channels of the relativistic charged-particle beams
Authors: Averyanov G P , Budkin V A , Dmitrieva V V
Published: November 2019

Considered the numerical simulation technique which providing optimum beam parameters at the transport channel output of electron accelerator. The KATRAN channels design environment used for this purpose has a modular structure includes the basic beam focusing blocks. This allows enabling create and configure the optical system of the accelerator fast and efficiently if a given topology of the transport channel.
Investigation of muon bundles generated by UHECR by means of the new coordinate-tracking detector
Authors: Zadeba E A , Borisov A A , Fakhrutdinov R M , Ivanov S S , Kokoulin R P , Kompaniets K G , Kozhin A S , Petrukhin A A , Vorobyev V S , Yashin I I
Published: November 2019

The new coordinate-tracking detector based on drift chambers (CTUDC) is created in MEPhI. The detector represents two planes with total area of 30 m2 placed on the opposite sides of Cherenkov water detector of 2000 m3 volume. Each plane consists of 8 large multiwire drift chambers (4000x508x112 mm3). The key advantages of these chambers are a large effective area (1.85 m2) and a good coordinate and angular resolution with a small number of measuring channels. From the beginning of 2017, CTUDC operates as a part of the experimental complex NEVOD. The detector is designed for measuring of high density muon bundles (up to 10 particles per m2) at zenith angles in the range from 30° to 90°. The results of the CTUDC operation during the last year are given, the first distributions of the events in zenith angle, muon bundle multiplicity and density obtained from the detector data are discussed.
Project on searching for neutron-antineutron oscillation at the WWR-M reactor
Authors: Fomin A , Serebrov A , Chaikovskii M , Zherebtsov O , Murashkin A , Golubeva E.
Published: November 2019

Supersource of ultracold neutrons on the basis of superfluid helium is under construction in PNPI NRC KI. It must provide UCN density 2-3 orders of magnitude higher than existing sources. For the new source we propose an experiment on search for neutron–antineutron oscillations based on the storage of ultracold neutrons in a material trap. The sensitivity of the experiment mostly depends on the trap size and the amount of UCN in it. The geometric configuration of the experimental setup was developed based on the MC simulations of neutrons trajectories into the trap. To calculate detector efficiency the GEANT4 model of the detector was created.
New method of high-energy gamma ray direction reconstruction in multilayered converters
Authors: Kheymits M D , Galper A M , Arkhangelskaya I V , Arkhangelskiy A I , Bakaldin A V , Gusakov Yu V , Dalkarov O D , Djivelikyan E A , Egorov A E , Leonov A A , Naumov P Yu , Pappe N Yu , Runtso M F , Stogkov Yu I , Suchkov S I , Topchiev N P , Yurkin Yu T , Zverev V G
Published: November 2019

A new method of high-energy gamma ray incident direction reconstruction is developed for gamma-ray detectors with multilayered converters. The method uses data from converter and, if available, from position-sensitive calorimeter to reconstruct an electromagnetic cascade axis and to determine the incident direction of a primary gamma. For the first time to find point of intersection of gamma direction line with convertor plane, median of energy deposit in sensitive plane of convertor is used. Applied, for example, to the GAMMA-400 space-based gamma-ray telescope this method allowed to achieve the angular resolution ∼0.01° at gamma-ray energy of 100 GeV, being much better than accuracy of the past and present space- and ground-based experiments. In the algorithm presented, a balance between the angular resolution and the effective area can be found to meet a scientific goal of an experiment.
Status of the Russian-Italian experiment NEVOD-EAS
Authors: Chiavassa A , Shulzhenko I A
Published: November 2019

The NEVOD-EAS air shower array is currently under construction in MEPhI, within the Russian-Italian NEVOD-DECOR partnership. The goal of the array is to provide an independent measurement of the size, of the core location and of the arrival direction of the extensive air showers (EAS) detected with the other facilities of the Experimental complex NEVOD. These measurements will provide a calibration of a novel perspective technique developed in the Experimental complex NEVOD for studying inclined muon bundles – the method of local muon density spectra. The array will also extend the opportunities of the Experimental complex NEVOD in carrying out multi-component studies of extensive air showers. The present status of the NEVOD-EAS air-shower array is described and the future perspectives are discussed.
Overview of Hypernuclei Reconstruction at NICA/MPD
Authors: Ilieva M , Zinchenko A , Kolesnikov V
Published: November 2019

The study of the formation of a dense and hot baryonic matter is the main goal of exploration for the NICA/MPD project. Strangeness production in nuclear collisions is a key part of the MPD project physics program and is an important tool for studying the QCD phase diagram. An overview of the relevant characteristics for hypernuclei reconstruction in the NICA energy range with the simulated MPD detector are presented. Focus is put on invariant mass distributions, reconstruction efficiency and expected yields.
Electric arc plasmatorch of a two-chamber scheme with reverse polarity of electrodes connection
Authors: Batomunkuev D Y , Vashenko S P
Published: November 2019

The work is a study of the operating parameters of the plasma torch of a two-chamber scheme with reverse polarity of connection the electrodes. Classical erosion levels of 1.81×10−6 g·Cl−1 and 2.675×10−7 g·Cl−1 for the cathode and anode, respectively, were obtained. Also, on the reverse polarity of the inclusion, the voltage is obtained by 31.8% higher compared to the voltage with the direct polarity of connection.
On the influence of a cathode shape on the parameters of current pulses of runaway electron beams in a gas discharge when applying voltage pulses with a rise time of 200 ns
Authors: Beloplotov D V , Tarasenko V F
Published: November 2019

The influence of the shape of a cathode on the duration and amplitude of a supershort avalanches electron beam (SAEB) current pulses was experimentally studied. Three cathodes were used in experiments: tube, needle, and ball. Voltage pulses with a rise time of 200 ns were applied across an 8.5 mm gap filled with air and nitrogen at various pressures (12.5–100 kPa). It was found that at an air pressure of 12.5 kPa and a rise time of voltage pulses 200 ns, the largest amplitudes of SAEB current pulses (90 mA) were observed with the tubular cathode. The SAEB current pulse duration was τ0.5 ~ 130 ps. Two pulses with different duration, amplitude and energy of electrons were observed with the needle cathode at same pressure. When using the ball cathode, the duration and amplitude of the beam current pulses were τ0.5 ~ 250 ps and ~ 4 mA, respectively.
Delay in plasma generation on the surface of coper and duralumin conductors coated with dielectrics
Authors: Datsko I M , Labetskaya N A , Rybka D V , Vankevich V A , Shugurov V V
Published: November 2019

The skin explosion was investigated for homogeneous and double-layer cylindrical copper and duralumin conductors coated with zirconium dioxide. The MIG generator used in the experiment produced a current of amplitude up to 2.5 MA and rise time 100 ns. To detect the plasma generated on the surface of a conductor due to its electrical explosion, the light emitted by the plasma was imaged using a four-frame optical camera with a frame exposure time of 3 ns. In addition, vacuum x–ray diodes were used to detect the instant at which the temperature of the surface plasma, assumed to be a blackbody, became greater than 1 eV. The internal structure and density of the surface plasma were examined based on its transmission images. The images were taken by exposing the plasma to the x-radiation with hν > 1 keV generated by an X-pinch for 2–3 ns. The QUINTA facility was used to carry out plasma-assisted deposition of multilayer coatings composed of alternating 0.8-μm-thick zirconium dioxide layers and (more durable) 0.2-μm-thick zirconium layers. The total number of layers in a coating could be up to sixteen. At magnetic fields lower than 300 T, the onset of plasma generation on the dielectric-coated load part occurred with a delay of up to 70 ns relative to that on a bare copper or duralumin conductor. Increasing the field to 350–400 T decreased the delay in plasma generation to about 30 ns.
Measurement of plasma parameters in an electron source with a plasma cathode based on a low-pressure arc discharge
Authors: Doroshkevich S Yu , Vorobyov M S , Kovalsky S S , Lopatin I V , Koval N N , Sulakshin S A
Published: November 2019

In the electron source with a grid plasma cathode based on a low-pressure arc discharge, the parameters of the emission plasma were investigated depending on the different conditions of its generation (type of gas, operating pressure, discharge current amplitude, resistance in the hollow anode circuit of a plasma emitter). For this purpose, a single cylindrical Langmuir probe was used. To measure the current-voltage characteristics of the probe, taking into account the features of the functioning of the electron source (galvanic isolation from high accelerating voltage, the use of high-voltage cables with high parasitic parameters, etc.), an automated measurement circuit was used, allowing for a relatively short time to collect high statistics of experimental data (depending on the frequency the impulses of the discharge current and their total number). To eliminate the influence of the parasitic parameters of the circuit, the measurement circuit was located in the maximum proximity to the generation space of the emission plasma (in a vacuum chamber), which significantly increased the accuracy of the experimental data obtained.
A limit value of the volume discharge ignition frequency in dense gases
Authors: Kozlov B A
Published: November 2019

There is deduced analytical expression for maximum value of the volume discharge ignition frequency in dense gases. That expression indicates the way for achieve maximal values of pulse repetition rates in CO2-lasers at atmospheric and super-atmospheric pressures. The increasing of pulse repetition rates is connected with sectioning of main discharge gap and excitation of volume discharge in each section from separate pulse pumping generator. This work is devoted to describing of constructions and main characteristics of some types compact pulse generators with amplitude of voltage pulses up to 200 kV, rise-times about 10 nanoseconds and pulse energy per pulse up to 20 J. For reduction of rise-time of high-voltage pulses were used spark-discharge two electrodes commutators (sharpeners) at working pressures up to 100 atm.
Study of ionization waves in a pulse discharge in argon
Authors: Kurbanismailov V S , Ragimkhanov G B , Tershonok D V , Khalikova Z R
Published: November 2019

In the article we present the results of the investigation of the initial stage of nanosecond discharge formation in inhomogeneous pre-ionized argon of atmospheric pressure. The peculiarities of the cathode directed ionization wave development between two flat electrodes in argon of atmospheric pressure are presented.
Study of ionization waves in a pulse discharge in helium
Authors: Kurbanismailov V S , Omarov O A , Ragimkhanov G B , Tershonok D V
Published: November 2019

The paper presents the results of experimental and numerical studies of the space-time dynamics of the formation of a discharge in helium under conditions of preliminary ionization of the gas. The effect of local field amplification regions on the discharge development is studied.
Study of the ion plasma flow generated by a high-current vacuum arc
Authors: Morozov P A , Punanov I F , Emlin R V , Muziukin I L , Chaikovsky S A , Uimanov I V , Shmelev D L , Zemskov Yu A , Mikhailov P S
Published: November 2019

The vacuum arc discharge is intensively explored for a long time. It acts as a source of multiply charged plasma. The results of the special type plasma gun (5–10 kA, 12 μs) ion flow study with high temporal resolution and the electrode erosion dependences on the amplitude of the current pulse are presented in the research. The ion flow intensity had good reproducibility from series to series, while the values of total mass erosion differ significantly for different series of experiments under the same conditions. The ion erosion was measured to be significantly higher than that for arc sources with currents up to 1 kA.
On the nature of charged particle flow of vacuum arc
Authors: Muzyukin I L , Mikhailov P S
Published: November 2019

Time resolving investigations of charged particles flow from the cathode region of the vacuum arc reveal that the basis of charged particles flow is short-term burst. These bursts can form sequences, groups with a relatively smooth waveform and superbursts. The Fourier analysis showed that ion flow has a brown-like frequency law. This fact can serve as evidence of the fractal nature of the cathode spot. However, the detailed analysis of ionsand accelerated electron signals revealed that the fractal nature of charged particle signal can reflect the fractal nature of plasma turbulences in discharge plasma. Also, the strong correlation between intensive charged particle flow appearance and arc discharge parameter instabilities was revealed. Thus, the plasma instabilities can be considered as the cause of ion and electron flow acceleration in the vacuum arc.
The space charge formed by the runaway electron beam
Authors: Oreshkin E V
Published: November 2019

For discharges in atmospheric pressure air, a numerical simulation of the process of formation of a runaway electron beam from the emission zone at the cathode was performed. The model is based on the numerical solution of the equations of motion of electrons injected from the surface of the emission zone and secondary electrons that appeared during gas ionization. It is shown that when a beam of runaway electrons passes through, a space charge is formed, which determines the electric field in the interelectrode gap.
Measuring the expansion velocity of plasma formed during electrical breakdown along an exploding al foil in a medium of desorbed gases
Authors: Rousskikh A G , Zhigalin A S , Oreshkin V I , Baksht R B
Published: November 2019

This paper reflects the experimental results on the measurement of the expansion rate of the plasma formed during an electrical breakdown along the exploding Al foil. Electric breakdown took place in a mixture of gases that being desorbed from the surface of the foil as it heated by a current passing. Aluminum foil size: length 20 mm, thickness 6 µm and the width was varied in the range from 0.93 mm to 1.05 mm. The explosion of the foil was carried out by a sinusoidal current with an oscillation period of 1780 ns. The amplitude of the current I varied depending upon the voltage charge (Uch
= 10, 20 and 30 kV) of 0.25 µF capacitor was about 6.5, 14 and 22 kA accordingly. The measurements of the expansion rate of the plasma was carried out using three electrical probes located beneath an ground potential, near the edges and in the middle of the exploding foil, in the process, the distance from the foil to the electrical probe was varied from 2 mm to 16 mm. In the experiment we measured the time of the signal appearance relative to the moment of electrical breakdown occurrence along the foil. The rate of plasma expansion was calculated by measuring the time of plasma span from the foil to the probe with consideration of the distance to the probes.
Temperature gradients in targets with high-intensity implantation and their influence on the characteristics of ion-modified layers
Authors: Ryabchikov A I , Lopatin I V , Ananin P S , Bleicher G A , Ivanova A I , Koval T V , Modebadze G S , Sivin D O
Published: November 2019

This paper is devoted to the study of the gradient temperature field dynamics and distribution in the metal targets irradiated with high-intensity beams of gas and metal ions. The investigations concerned ion implantation modes with the ion beam current density from several tens of mA·cm−2 up to A·cm−2 were investigated. The ion beam power was additionally varied due to the change of ion energy in the range from 0.6 to several keV and the pulse duty factor in the range of 0.2–0.8. The integral temperature of the target was measured with an electrically isolated thermocouple. To measure the dynamic change in the local temperature on the irradiated target a high-temperature pulse pyrometer KLEIBER 740-LO was used. The problem of temperature evolution and metal sample melting under the exposure of a high-intensity repetitively pulsed ion beam was solved numerically using the heat conduction equation written in cylindrical coordinates. Analysis of the experimental data obtained with the use of electrically isolated thermocouple, pulse pyrometer, and numerical simulation revealed the presence of significant gradient temperature fields both over the surface and along the depth of targets irradiated by high-intensity ion beams.
Plasma potential around a single-dimensional dust particle chain placed in an external electric field
Authors: Salnikov M V , Fedoseev A V , Sukhinin G I
Published: November 2019

In this paper a model that allows to self-consistently calculate the potential distribution and plasma space charge distribution near an infinite one-dimensional chain consisting of highly charged dust particles, which is influenced by an external electric field, is presented. The results show that with a gradual increase of the external field amplitude, unlike in the case of an isolated dust particle, there is no anisotropy in the distribution of the space charge; however, with a further increase of the electric field power, zones of local potential maxima appear between the dust grains.
Comparison of plasma parameters and optical emission in DC, HIPIMS and hybrid DC+HIPIMS modes of magnetron sputtering
Authors: Semenov V A , Grenadyorov A S , Oskirko V O , Zakharov A N , Rabotkin S V , Ionov I V , Solovyev A A
Published: November 2019

Experimental studies of the parameters of the plasma of a magnetron discharge and optical radiation from plasma in the regime of direct current (DC), high-current mode (HIPIMS), and hybrid (DC+HIPIMS) mode for a copper cathode 100 mm in diameter were carried out. The hybrid mode of operation of the magnetron sputtering system was carried out by means of a matching unit of two power supplies APEL-M-5HIPIMS and APEL-M-5PDC. The results of the experiments showed that the plasma concentration at a distance of 120 mm from the cathode has maximum values (5.6·1011 cm−3) in the HIPIMS regime at a frequency of 500 Hz. Measurement of the optical emission spectra for a copper cathode in an argon plasma showed, that at the same average discharge power (500 W), the intensity of the copper ion lines in the high-current and hybrid modes is 3 and 1.5 times, respectively, more than in the DC regime.
Modeling of plasma jet of vacuum arc with copper-chromium cathode under action of strong axial magnetic field
Authors: Shmelev D L , Uimanov I V , Frolova V P
Published: November 2019

This paper deals with the computer simulation of a vacuum arc with composite cathode under action of external axial magnetic using hybrid model. The described hybrid model treats the electrons as a massless fluid and ions as macroparticles. It is shown that the average charge state of ions in a jet of a vacuum arc increases with increasing magnetic field. The calculation results are consistent with experimental data.
Simulation of high-pressure gas breakdown under conditions of spatially non-uniform initial ionization and temperature
Authors: Sitnikov A G , Kozyrev A V , Kozhevnikov V Yu , Kokovin A O , Semeniuk N S
Published: November 2019

The paper presents the results of numerical simulation of the extended atmospheric pressure discharge in configuration of the tip-to-plane diode. The simulation is based on a hydrodynamic model of a discharge plasma in a pure O2medium at low average electric field strengths ~ 10 kV·cm−1. It was investigated how initial conditions, such as the presence of a weakly ionized plasma channel or a given temperature profile on the discharge axis, influence on the formation of a discharge structure at the initiation stage.
Discharge features in crossed electric and magnetic fields
Authors: Strokin N , Bardakov V , Kazantsev A , Nguyen Thang , Stupin A , Kuz’mina A
Published: November 2019

The article discusses the study of a self-sustained discharge in the plasma accelerator with closed electron drift and the anode layer. Dependencies of the density and the average energy of ions on the magnitude and direction of the magnetic field induction vector n = f(BrA
), Wav
= f(BrA
) characterized by minimum and maximum values of n and Wav
have been discovered. It has been determined that the most efficient and optimal modes of discharge combustion are achieved when n and Wav
reach the maximum. The density rose to nopt
/n ≈ 5.5, and the average ion energy increased by 1.6 times. The evidence of “breakdowns” of density upon the change in the magnetic field is provided. The concept of isomagnetic jumps for the energy spectra of ions is introduced; their evolution is traced upon the change in discharge parameters. A theoretical model establishing the mechanisms of energy gain and loss by electrons has been proposed. It determines the formation of the ion energy distribution function as well as the ion density in the discharge gap. Likewise, the model explains various dependencies of the ion density upon the growth of the magnetic field and the “breakdown effect” of the ion density.
Some features of the electric discharge with the anode as a liquid electrolyte flow
Authors: Tazmeev G K , Tazmeeva R N
Published: November 2019

An electrical discharge between a liquid electrolyte anode and metal cathode was experimentally investigated. Sodium chloride solutions in distilled water with a mass concentration of 2–10 g·l−1 were used as electrolyte. The study was conducted in the range of currents of 0.1–3.5 A. The photo and video methods recorded features in the spatial structure of the electric discharge, which were manifested with an increase in current and variation of the discharge gap geometry. The conditions under which a volume discharge is formed in the diffuse combustion mode are revealed. A threshold current has been established, above which a contracted discharge channel is formed. The emission spectrum of the discharge in the visible region of the spectrum was studied.
Simulation of electron beam generation with a constant, rising and falling beam power during its pulse
Authors: Vorobyov M S , Kovalsky S S
Published: November 2019

In this work, we simulated the operation of an electron source with a grid plasma cathode based on a low-pressure arc discharge, where a high-voltage capacitor bank of a given capacity is used to accelerate the beam electrons. Based on the unique ability of such electron sources to generate electron beams with parameters independent of each other, capable of being regulated within relatively wide limits, the calculations were carried out with the aim of producing an electron beam whose power can be controlled during a beam pulse of a millisecond duration when the beam power is constant or has a linear rise or fall. The calculations confirm the uniqueness of plasma electron sources and open up new possibilities for their use in scientific and technological purposes.
Dependence of the plasma composition in the low-current vacuum arc discharge on CuCr cathode on the current value and surface conditions
Authors: Zemskov Yu A , Uimanov I V
Published: November 2019

The dependence of the ion flux mass-charge composition from the vacuum arc plasma with the CuCr cathode on a value of the discharge current was investigated via the Thomson spectrometer with automatic signal registration and analysis. The microsecond arc was formed in a millimeter gap between CuCr cathode and copper anode under high vacuum conditions. The arc current was changed within the range from a few to tens of ampere. At the highest currents the plasma composition corresponded the elemental composition of the cathode surface. The fraction of the chromium ions significantly decreased with the arc current decreasing below 30 A. There was noticeable increasing of the fraction of the chromium ions in the plasma at the discharge currents near the threshold values for the cathode materials. The effect appeared on coarse-grained non-melted cathode surfaces, and vanished after a multiple arcing.
Powerful source of VUV-UV radiation based on nanosecond volumetric discharge
Authors: Baryshnikov V I , Chirkov V Y , Paperny V L
Published: November 2019

The radiation of a volumetric gas discharge in xenon, excited by a compact high-current (5 kA) high-voltage (about 300 kV) sub-nanosecond generator, was investigated using a fast pin-diode. It was shown that the radiation lies mainly in the range of the vacuum ultraviolet with a wavelength of less than 200 nm, and the radiation intensity does not depend on the pressure of the working gas in the investigated range of 0.1–3.0 atm.
Switching devices – EPTRON with 100 kV operating voltage and sub-nanosecond switching times
Authors: Bokhan P A , Gugin P P , Kim V A , Lavrukhin M A , Zakrevsky D E
Published: November 2019

The data on the experimental study of the characteristics of a gas-discharge switching device consisting of an open discharge section with generation of counter propagating electron beams acting as an electron emitter, and a capillary discharge section providing a large time delay for the development of the discharge τ
d
and a rapid recombination of the plasma after the passage of the current pulse are presented. The ability of this device to operate at voltages up to 100 kV, while maintaining a delay time τ
d
of the order of several hundred ns and subnanosecond capillary breakdown τ
sc
, is demonstrated. The τ
sc
voltage independence in the range of helium pressures p
He = 6–30 Torr was found.
Profile formation of emission current of grid plasma cathode in a longitudinal magnetic field
Authors: Devyatkov V N , Koval N N
Published: November 2019

The paper presents a gas discharge system for a grid plasma cathode which provides the generation and transport of an intense pulsed (20–250 µs) electron beam with an energy of up to 25 keV and current of up to 500 A (against its nominal value of 300 A) in a longitudinal magnetic field of 20–50 mT. The main feature of the plasma-cathode discharge system is its stable operation with no discharge constriction in an inhomogeneous magnetic field (5–30 mT) which penetrates in the system from the beam transport region. The system shows stable initiation and operation of its main discharge without current cutoffs at an argon pressure of (2–8)×10–2 Pa, which has been attained by optimizing the geometry of its electrodes as well as the position and orientation of its permanent magnets. When transported in a magnetic field, the beam current reaches its maximum at the beam center. For controlling the cross-sectional beam homogeneity, the initial distribution of the emission current from the plasma cathode is varied by varying the magnetic field penetrating in the discharge system and the current flow at its redistributing electrode. Such corrections of the initial current from the cathode provides a more homogeneous (±10%) energy distribution over the beam cross-section after transport to a distance of 300 mm.
Microwave complex for obtaining low-temperature plasma at atmospheric pressure
Authors: Ivanov I A , Tikhonov V N , Tikhonov A V
Published: November 2019

Over the past two decades, the scientific and technological community has made significant efforts to develop, maintain and use atmospheric non-thermal (ANT) plasma because of its numerous scientific and industrial applications. The hardware complex was designed and manufactured to produce low-temperature and ANT plasmas at atmospheric pressure. The base of the designed complex is powerful (up to 3 kW) and inexpensive magnetron microwave generator. The complex includes three types of applicators, splitter, cable assembly and water load. The splitter allows adjustable sampling of microwave power from the waveguide path to the payload by 50 Ohm coaxial cable in the range from 0 to 400 W.
Formation of pulsed large-radius electron beam in the forevacuum pressure range by a plasma-cathode source based on arc discharge
Authors: Kazakov A V , Medovnik A V , Oks E M
Published: November 2019

The research on generation and propagation of large-radius low-energy (up to 10 keV) electron beam with millisecond pulse duration by the plasma-cathode electron source in the forevacuum pressure range (3–30 Pa) is presented. An arc discharge with cathode spot has been used to generate emission plasma with millisecond pulse duration. Large hollow anode and ball-shaped redistributing electrode have provided formation of arc plasma with emission surface of 100 cm2; emission plasma boundary has stabilized by metallic mesh. It is established, that gas type and gas pressure affect the parameters of the arc discharge. In case of gases with greater ionization cross section (argon, nitrogen), an increase of gas pressure has led to a decrease of arc voltage and to an increase of emission plasma density. Gas with small ionization cross section (helium) had weak effect on the arc discharge parameters. An increase of emission window in the anode has provided an increase in radius of the electron beam and an increase of efficiency of electron extraction from the arc plasma; on the other hand it has led to an increase of influence of back-streaming ion flow on the electron emission and led to a decrease of maximal operating gas pressure. Reducing the geometric transparency of the emission mesh, as well as the use of gas with small ionization cross section have provided an increase in the maximal operating pressure of the source of large-radius electron beam. It is established, that in the forevacuum pressure range, large-radius electron beam is efficiently generated in the investigated range of distances from the extractor up to 35 cm.
Generation of focused high-current electron beam with millisecond pulse duration by a forevacuum plasma-cathode electron source based on cathodic arc
Authors: Kazakov A V , Medovnik A V , Oks E M
Published: November 2019

We describe our work on the generation of low-energy (up to 10 keV) pulsed high-current electron beams with pulse duration up to 7 ms, compressed (focused) by a magnetic field in the forevacuum pressure range (3–30 Pa). We show that the focusing system, consisting of two coaxially arranged coils, provides effective compression of the beam. In the forevacuum pressure range, the gas pressure and type of gas affect the focusing of the beam at fixed emission current, accelerating voltage and magnetic field. Increased pressure leads first to increased beam current density, but beyond a certain optimal value further pressure increase leads to a decrease in the current density of the electron beam. The use of gas with greater ionization cross-section results in stronger compression of the beam at lower gas pressure, but also leads to decreased maximal operating gas pressure of the plasma-cathode electron beam source. Variation of magnetic fields provides control of the beam current density and the position of the beam crossover (focus). A low-energy electron beam with current density up to 15 A·cm−2 and pulse duration up to 7 ms is obtained in the forevacuum pressure range. The use of the focused beam for evaporation of high-temperature ceramics is demonstrated.
Operation features of the pulse penning ion source in the transition pressure range
Authors: Mamedov N V , Maslennilov S P , Solodovnikov A A , Yurkov D I
Published: November 2019

The paper presents the results of experiments studying the dependence of discharge and extracted currents on the pressure of pulsed penning ion source (PIS). A comparative analysis of the amplitude-time and current-voltage characteristics of PIS for the various anode voltage amplitudes, pulse repetition rates, pulse durations, magnitudes (and configurations) of the magnetic field is presented. The obtained results reveal the existence of different (stable and unstable) discharge modes depending on the operating conditions of the power supply system and the pressure range of the working gas (deuterium). The features of current waveforms in the transitional pressure range 0.5–2 mTorr are defined.
Angular distribution of mass and charge flows in far zone of plasma beams generated by nanosecond vacuum surface flashover at 70 kV
Authors: Morozov P A , Emlin R V , Punanov I F , Shcherbakov Ye N
Published: November 2019

In this work, we measure directional patterns of charge flow of ions and mass flow of neutrals in particle beam generated by vacuum surface flashover in linear configuration at voltage of 70 kV. We used a generator, which provide a discharge current of 2.8 kA. The samples used are polymethylmethacrylate, polytetrafluorethylene and polyethylene. We found that the directional patterns of mass and charge flows in linear configuration have distinct axial asymmetry. The corresponding angular distributions are significantly wider in the plane which is normal to the discharge than in the plane which contains the discharge. Angular distributions of charge flow are wider than distributions of neutral mass flow in the same planes. Besides, the asymmetry in ion current amplitudes at the cathode side and at the anode side is observed. We found that the share of low-velocity ions in ion current drops drastically in the plane which contains the discharge at the angles of 15 degrees and larger for all the tested materials.
Plasma source for auxiliary anode plasma generation in the electron source with grid plasma cathode
Authors: Moskvin P V , Devyatkov V N , Lopatin I V , Vorobyov M S
Published: November 2019

This paper presents an auxiliary source of anode plasma developed for the electron source with a plasma cathode based on a low-pressure arc discharge. The plasma source consists of three cells: the main ion-plasma system with closed electron drift and two auxiliary ones. The latter include a hollow cathode and a reflective discharge cell. The construction allows to generate and transport a submillisecond low-energy beam up to 25 keV with a diameter of 40 mm in axial magnetic field up to 80 mT. In the main mode of the auxiliary discharge, the anode plasma is created at a current of up to 15 A and with discharge voltage about 300 V. Using the source of auxiliary anode plasma allows you to expand the range of operating pressures of the electron source down to 3.6×10−3 Pa of argon and get rid of high-frequency beam current oscillations when operating at low pressure (up to 1.2×10−2 Pa).
Generation of atmospheric pressure plasma in molecular gas flows
Authors: Savkin K P , Bugaev A S , Gushenets V I , Vizir A V , Nikolaev A G , Oks E M , Yushkov G Yu , Shandrikov M V , Frolova V P , Bin Zhang , Gao Kaixiong
Published: November 2019

We have investigated an atmospheric pressure discharge, similar to a plasma jet, in the N2 and CO2 gas flows. We have also carried out an experimental modeling with the argon Ar flow. It has been shown that the use of a tantalum cathode and a copper anode provides a stable discharge in the nitrogen and carbon dioxide flows. We have studied the dependence of the discharge voltage on the discharge current (VAC). Optical emission spectra of discharge glow was investigated also. Using a single probe and a thermocouple, we have studied the axial distribution of the floating potential in the plasma jet and the gas temperature at the anode nozzle exit of the plasma generator. In applying to polymer surface modification, we have determined the optimal operation conditions: gas flow rate up to 5 l·min−1; continuous or pulsed working regime; discharge current about 80 mA; pulse duration up to 10 µs; pulse repetition rate 50 kHz.
Pulsed fields influence on PIG ion source performance
Authors: Schitov N N
Published: November 2019

The investigations of pulsed fields influence on PIG ion source performance preliminary results are presented. Fields are generated at the storage capacitance discharge through flat spiral antennas being cathodes of a Penning cell in H2. Theoretical estimates of the ionization probability at different discharge regimes are given. The experimental unit designed to investigate these regimes at different electrode system configuration, electrophysical and geometrical parameters as well as an external constant magnetic field is described. The experimental results are shown in comparison with theoretic estimates.
Partial discharge analysis through Lissajous figure at low air pressures
Authors: Shi Z , Zhang C , Given M
Published: November 2019

The condition of electrical insulation is significant to the safety of electric power systems, especially to the More Electric Aircraft (MEA) that carries hundreds of people. The property of insulation will be reduced by aging and degradation which caused by partial discharge (PD). This has become a topic of extensive research and investigation. This paper represents the PD detection in terms of Lissajous figures which is a composite of two orthogonal oscillations with integral proportional frequencies. It can be used to calculate the total charge of PD transferred per cycle and the total energy of PD per cycle, thus the average charge and energy of a single PD activity can be recognized accompany with the current pulse PD detection method based on IEC 60270. These parameters could be useful to evaluate whether the insulation was damaged or how badly the damage was, hence to provide references to engineers for insulation condition judgment and design service plan.
The deflection of a wide electron beam from the longitudinal axis of the source with a plasma cathode and plasma anode
Authors: Shin V I , Moskvin P V , Vorobyov M S , Devyatkov V N , Doroshkevich S Yu
Published: November 2019

An electron source with a plasma cathode based on a low-pressure arc discharge having a grid (layer) stabilization of the emission (cathode) plasma boundary and the open edge of the anode plasma has been used to study the deflection of a broad intense submillisecond electron beam from the electron source axis by a leading magnetic field. Measurements of the energy density distribution of the generated electron beam were made both under conditions of its deflection and in the mode of “direct” transport, when the collector target is in direct line of sight from the emission electrode. It was experimentally shown that the stability of the electron source operation with a beam deflection significantly increases. It allows to expand the range of beam parameters, which opens up new possibilities for use the electron source for both scientific and technological purposes.
Spectral measurements in the plasma of microwave and magnetron discharges
Authors: Shipilova O I , Chernikh A A , Paperny V L
Published: November 2019

Spectroscopic methods were used to study the parameters of a low-power (≤ 100 W) magnetron discharge plasma, as well as a low-pressure microwave discharge (6–40 Pa) in argon. It is shown that in the magnetron discharge the concentration of atoms and ions of the buffer gas (Ar) and the target material (Cu) decreases exponentially with distance from the target cathode and in the first case it occurs much more sharply. The temperature of electrons in a plasma stream, which is emitted by a discharge burning near the surface of the cathode, was estimated from the relative intensity of the spectral lines according to the LTE model and the coronal model. The values obtained in both cases were close, lying near 1 eV, and the temperature remained almost constant with the distance from the cathode. The electron temperature in the microwave discharge turned out to be almost constant over the cross section of the plasma column, while the concentration near the microwave emitter was 2–3 times higher than in the rest of the column.
Beam plasma discharge in technologies of materials for nanoelectronics
Authors: Shustin E G
Published: November 2019

The technologies developed at V.A. Kotelnikov Institute of Radio Engineering and Electronics of RAS for specific application in nanoelectronics that are not used in industry are reviewed. Physical problems that were been solved at their development are analyzed, and found solutions are represented. Tested applications are briefly described.