bluuebunny/crossref_metadata_2025 huggingface dataset:
Dark matter with chiral symmetry admixed with hadronic matterin compact stars *
Authors: Wei Si-Na , Feng Zhao-Qing
Published: November 2021

Using the two-fluid Tolman-Oppenheimer-Volkoff equation, the properties of dark matter (DM) admixed neutron stars (DANSs) have been investigated. In contrast to previous studies, we find that an increase in the maximum mass and a decrease in the radius of 1.4

NSs can occur simultaneously in DANSs. This stems from the ability of the equation of state (EOS) for DM to be very soft at low density but very stiff at high density. It is well known that the IU-FSU and XS models are unable to produce a neutron star (NS) with a maximum mass greater than 2.0

. However, by considering the IU-FSU and XS models for DANSs, there are interactions with DM that can produce a maximum mass greater than 2.0

and a radius of 1.4

NSs below 13.7 km. When considering a DANS, the difference between DM with chiral symmetry (DMC) and DM with meson exchange (DMM) becomes obvious when the central energy density of DM is greater than that of nuclear matter (NM). In this case, the DMC model with a DM mass of 1000 MeV can still produce a maximum mass greater than 2.0

and a radius of a 1.4

NS below 13.7 km. Additionally, although the maximum mass of the DANS using the DMM model is greater than 2.0

, the radius of a 1.4

NS can surpass 13.7 km. In the two-fluid system, the maximum mass of a DANS can be larger than 3.0

. Consequently, the dimensionless tidal deformability

of a DANS with 1.4

, which increases with increasing maximum mass, may be larger than 800 when the radius of the 1.4

DANS is approximately 13.0 km.
Real-time removal of stimulation artifacts in closed-loop deep brain stimulation
Authors: Nie Yingnan , Guo Xuanjun , Li Xiao , Geng Xinyi , Li Yan , Quan Zhaoyu , Zhu Guanyu , Yin Zixiao , Zhang Jianguo , Wang Shouyan
Published: November 2021

Objective. Closed-loop deep brain stimulation (DBS) with neural feedback has shown great potential in improving the therapeutic effect and reducing side effects. However, the amplitude of stimulation artifacts is much larger than the local field potentials, which remains a bottleneck in developing a closed-loop stimulation strategy with varied parameters. Approach. We proposed an irregular sampling method for the real-time removal of stimulation artifacts. The artifact peaks were detected by applying a threshold to the raw recordings, and the samples within the contaminated period of the stimulation pulses were excluded and replaced with the interpolation of the samples prior to and after the stimulation artifact duration. This method was evaluated with both simulation signals and in vivo closed-loop DBS applications in Parkinsonian animal models. Main results. The irregular sampling method was able to remove the stimulation artifacts effectively with the simulation signals. The relative errors between the power spectral density of the recovered and true signals within a wide frequency band (2–150 Hz) were 2.14%, 3.93%, 7.22%, 7.97% and 6.25% for stimulation at 20 Hz, 60 Hz, 130 Hz, 180 Hz, and stimulation with variable low and high frequencies, respectively. This stimulation artifact removal method was verified in real-time closed-loop DBS applications in vivo, and the artifacts were effectively removed during stimulation with frequency continuously changing from 130 Hz to 1 Hz and stimulation adaptive to beta oscillations. Significance. The proposed method provides an approach for real-time removal in closed-loop DBS applications, which is effective in stimulation with low frequency, high frequency, and variable frequency. This method can facilitate the development of more advanced closed-loop DBS strategies.
Determination of the characteristic magnetic pre-sheath length at divertor surfaces using micro-engineered targets on DiMES at DIII-D
Authors: Abe S. , Skinner C.H. , Bykov I. , Yeh Y.W. , Lasa A. , Coburn J. , Rudakov D.L. , Lasnier C.J. , Wang H.Q. , McLean A.G. , Abrams T. , Koel B.E.
Published: November 2021

The magnetic pre-sheath (MPS) length, L
MPS, is a critical parameter to define the sheath potential, which controls the ion trajectory of low-Z species (D, T, He, and C), as well as the prompt re-deposition of high-Z species. To determine L
MPS, we fabricated micro-trenches (30 × 30 × 4 μm) via focused ion beam milling on a silicon surface and exposed them to L-mode deuterium plasmas in DIII-D via the divertor material evaluation system (DiMES) removable sample exposure probe. The areal distribution of impurity depositions, mainly consisting of carbon, was measured by energy-dispersive x-ray spectroscopy (EDS) to reveal the deuterium ion shadowing effect on the trench floors. The carbon deposition profiles showed that the erosion was maximized for the azimuthal direction of φ = −40° (referenced to the toroidal magnetic field direction) as well as the polar angle of θ = 80°. A Monte Carlo equation-of-motion (EOM) model, based on a collisionless MPS, was used to calculate the azimuthal and polar deuterium ion angle distributions (IADs) at the surface for a range of L
MPS = k × ρ
i, where ρ
i is the ion gyro radius and k = 0.5–4. Then, gross erosion profiles were calculated by a Monte Carlo micro-patterning and roughness (MPR) code for ion sputtering using as input the calculated azimuthal and polar IADs for each value of k. Good agreement with the experimental C deposition profiles was obtained for the case k = 2.5–3.5. This result is consistent with a previous kinetic modeling prediction of k ∼ 3, as well as previous analytical investigations that predicted the L
MPS to be several ion gyro radii. A validation of theoretical sheath models supports its applicability to ITER and pilot plant divertors to successfully predict plasma–materials interactions.
Novel internal measurements of ion cyclotron frequency range fast-ion driven modes
Authors: Crocker N.A. , Tang S.X. , Thome K.E. , Lestz J.B. , Belova E.V. , Zalzali A. , Dendy R.O. , Peebles W.A. , Barada K.K. , Hong R. , Rhodes T.L. , Wang G. , Zeng L. , Carter T.A. , DeGrandchamp G.H. , Heidbrink W.W. , Pinsker R.I.
Published: November 2021

Novel internal measurements and analysis of ion cyclotron frequency range fast-ion driven modes in DIII-D are presented. Observations, including internal density fluctuation (

n

~

) measurements obtained via Doppler backscattering, are presented for modes at low harmonics of the ion cyclotron frequency localized in the edge. The measurements indicate that these waves, identified as coherent ion cyclotron emission (ICE), have high wave number, k
⊥
ρ
fast ≳ 1, consistent with the cyclotron harmonic wave branch of the magnetoacoustic cyclotron instability, or electrostatic instability mechanisms. Measurements show extended spatial structure (at least ∼1/6 the minor radius). These edge ICE modes undergo amplitude modulation correlated with edge localized modes (ELM) that is qualitatively consistent with expectations for ELM-induced fast-ion transport.
On

P

Wπ-regular rings
Authors: Mahmood Raida D. , Khider Khedher J.
Published: November 2021

As a popularization of weakly π-regular rings, we tender the connotation of W

P

Wπ-regular rings, that is if for each 𝔞 ∈ Ɉ(𝔑), there exist a natural number 𝔫 such that 𝔞𝔫 ∈ 𝔞𝔫 𝔑 𝔞𝔫 𝔑 (𝔞𝔫 ∈ 𝔑 𝔞𝔫 𝔑 𝔞𝔫). In this treatise, numerous properties of this sort of rings are discussed, some important results are secured. Using the connotation of

P

Wπ-regular rings. It is show that :

1- Let 𝔑 be a right

P

Wπ-regular ring and ℵɈ-rings with 𝔞𝔫𝔑 = 𝔑𝔞𝔫
for every 𝔞 ∈ Ɉ(𝔑) and for at least one of a natural number. Then Ɉ(𝔑) = ℵ𝔑.

2- Let 𝔑 a right

P

Wπ-regular ring and 𝔞𝔑 = 𝔑𝔞 for each ∈Ɉ(𝔑). Then 𝔑 is right

P

.𝔗-ring.

3 Let 𝔑 be a ring with ɍ(𝔞) ⊆ ɭ(𝔞), for each ∈ Ɉ (𝔑). If any of the next conditions are hold, then 𝔑 is

P

Wπ-regular rings :

i – Every maximal right ideal of 𝔑 is a right annihilator and right Ɉ

PP

-ring.

ii – any simple singular right 𝔑-module is Ɉ-injective and 𝔑 is semi prime.
15th International Conference “Gas Discharge Plasmas and Their Applications”
Authors: Mesyats G A , Chaikovsky S A , Zubarev N M , Kaygorodov A S , Kokorina E E
Published: November 2021

This paper is a preface to the proceedings of the 15th International Conference “Gas Discharge Plasmas and Their Applications”, which was held in Ekaterinburg, Russian Federation on September 5 to 10, 2021.
Different modes of runaway electron beams generated in high-pressure gases
Authors: Tarasenko V F , Sorokin D A , Beloplotov D V , Lomaev M I , Baksht E Kh , Burachenko A G
Published: November 2021

This article presents the results of experimental studies of different modes of a runaway electron beam (RAEB) generation in high-pressure gases as well as X-rays caused by it. In particular, the mode with the greatest beam current amplitude, the one with two current pulses, that with the X-ray pulse duration of 100s ns, the mode in which a RAEB propagates in the direction opposite from an anode, and some others are described. The effect of the cathode design and material on the RAEB current amplitude and duration in atmospheric-pressure air is shown. When analyzing the most common modes, the features of the gap breakdown are used.
Instabilities of electrical properties of He-induced W “fuzz” within the pre-breakdown and breakdown regimes
Authors: Zemskov Yu A , Mamontov Yu I , Uimanov I V , Zubarev N M , Kaziev A V , Kharkov M M , Barengolts S A
Published: November 2021

The investigation of the He-induced W “fuzz” electrical properties was carried out. For the research, an automated experimental setup was designed. The setup was based on a vacuum chamber operated under high vacuum conditions (~ 10−7 Pa). The vacuum diode under investigation comprised of a flat W “fuzz” cathode with an area of about 1 cm2 and a 2 mm radius cylindrical copper anode with a hemisphere tip. The cathode-anode distance was about 100 μm. The voltage applied was up to 10 kV. A DAC/ADC module controlled an HV power supply and automatically registered currents and voltages in the circuit. The effect of a spontaneous change in the emissive ability of the investigated surface area was observed. These changes can vary significantly in magnitude. Large-scale changes can lead to a permanent increase in the emissive ability of a specific area or to a breakdown of the gap. Small changes, as a rule, are reversible, have a stepped nature, and make it difficult to record and interpret the current-voltage characteristics of the field emitter.
Runaway electron flows in magnetized coaxial gas diodes
Authors: Mesyats G A , Sharypov K A , Shpak V G , Shunailov S A , Yalandin M I , Zubarev N M
Published: November 2021

This paper presents the experimental results on applying a strong magnetic field (B) to increase the uniformity and density of a picosecond runaway electron flow (RAEF) formed in an air coaxial diode with a tubular cathode. A uniform longitudinal field Bz
allows to confine RAEF similarly to the electron beam in a magnetically insulated coaxial vacuum diode. Dependence of the spatial discreteness of RAEF emission and the transverse size of the emitting plasma regions on Bz
has been demonstrated. For the cathode diameter of 8 mm, a current density was significantly increased from 40 A/cm2 (at Bz
= const) to 100 A/cm2 by applying B-field with converging field lines. In the region of B maximum (5 T) the RAEF diameter was squeezed by ≈ 4 times.
Picosecond high-current discharge pumping of gaseous media emitting VUV-UV
Authors: Baryshnikov V I , Paperny V L
Published: November 2021

The possibility of creating small picosecond lasers in the VUV-UV spectral range by pumping by a high-current volume discharge of gaseous media (Xe and N2) at a pressure of 1-3 atm is investigated. Generation of picosecond (200 ps) powerful (1.2 MW) pulses at a wavelength of 337 nm at an N2 pressure of 1–3 atm has been achieved. Based on studies of high-current volume picosecond discharges in xenon, using VUV-UV spectroscopy, the presence of short-lived absorption of VUV radiation by discharge plasma was observed. A mechanism for the suppression of the formation of

Xe

2
*

dimers due to thermal effects at the stage of recombination of electrons with Xe+ ions at a plasma temperature of 105 K with a pulsed pump of 200 ps duration was suggested.
Measurement of the duration of runaway current pulses using measuring equipment with bandwidths up to 50 GHz
Authors: Beloplotov D V , Tarasenko V F , Sorokin D A , Ripenko V S , Leshchinskaia S B
Published: November 2021

The duration of current pulses of runaway electrons generated during the formation of a nanosecond discharge in air in a sharply inhomogeneous electric field was measured using measuring equipment with a bandwidth of 50 GHz. The influence of the gas pressure and the shape of a cathode on the duration of the RE current pulses is investigated. Current pulses with full width at half maximum of 16–28 ps were recorded, depending on the conditions.
Nanosecond breakdown in a pulsed open discharge
Authors: Bokhan P A , Glubokov N A , Gugin P P , Zakrevsky D E
Published: November 2021

The paper presents the results of studies of open discharge breakdown characteristics at nanosecond supply pulse in helium, neon, argon working medium in a wide pressure range. It is shown that the open discharge exists in the range of p
He = 20–100 Torr, pNe
= 1.5–25 Torr, p
Ar = 0.5–3.7 Torr with used experimental conditions. With increasing pressure, the role of separate elementary processes increases which can lead to a change of the discharge form to a presumably avalanche or streamer discharge. However, in this case, due to the photoemissive nature of the open discharge initiation, the similarity law Ep = f(pι) does not coincide with that for a nanosecond avalanche discharge.
The initial stage of the plasma formation at skin explosion of cylindrical conductors
Authors: Datsko I M , Labetskaya N A , Chaikovsky S A , Van’kevich V A , Oreshkin V I
Published: November 2021

The formation of plasma on the surface of the electrically exploded conductor is a key issue in terms of the energy introduced into the metal substance. The purpose of this work was to study the dynamics of dense plasma formation on the metal surface at magnetic induction values of 200-600 T and its rising rates of (2-6) T/ns. The experiments were carried out on a terawatt MIG generator with current amplitude up to 2.5 MA and rise time of 100 ns. In experiments, skin electrical explosion of cylindrical conductors made of different materials and with different diameters was studied. The formation of plasma on the surface of the conductor was recorded using a four-frame optical camera with an exposure time of 3 ns for each frame. It was shown that when the current increases, “spots” appear on the surface of a cylindrical conductor. These spots are the centers of plasma formation. Later in the time, longitudional plasma channels were registered. In course of subsequent merging of the channels relatively uniform plasma formation occurs. The paper discusses the features of the dynamics of plasma formation as a function of the peak and the rising rate of the magnetic field induction.
The measurements of vacuum arc behaviour at threshold current
Authors: Muzyukin I L , Mikhailov P S
Published: November 2021

The measurements of vacuum arc current parameters at the threshold current were made. The threshold currents for Cu, W, graphite cathodes were measured. It was shown that the current that vacuum arc chops with, has a statistical distribution. The vacuum arc current chopping is accompanied with significant ion current burst. The ion current of W and Cu cathodes contains intensive peaks with 30-50 ns duration. It was shown that the cathode materials that have intense peaks have a significant threshold current.
Determination of the conductor resistance during their explosion in vacuum under conditions of skinning the current
Authors: Rousskikh A G , Zhigalin A S , Oreshkin V I
Published: November 2021

The work is devoted to the investigation of the features of the conductor explosion in a vacuum under the conditions of skinning the current, and specifically, the effect of the magnetic field nonlinear diffusion wave spreading over the exploded conductor on its electrical properties. Experiments on the explosion of conductors were carried out on the IMRI-5 pulse power generator. The exploded conductor was soldered to the cathode and mechanically clamped between the plates on the anode. In the experiments, we used two types of conductors, cylindrical and flat (foils). Cylindrical conductors were of two types: copper (0.5 mm in diameter) and aluminum (0.44 mm in diameter). Foils were also of two types: copper with a thickness of 300 microns and aluminum with a thickness of 200 microns. The foil width varied from 1 to 3 mm. The length always remained 30 mm. To calculate the circuit inductance and calculate the corrections for the real conductor inductance, we used a load that was either a copper foil 600 μm thick and 1 cm wide, or a copper conductor with a diameter of 2 mm (short circuit mode).
Surface discharge during electrical explosion of conductors in strong magnetic fields
Authors: Oreshkin V I , Chaikovsky S A , Oreshkin E V
Published: November 2021

In experiments on the electrical explosion of conductors in rapidly growing mega-Gaussian magnetic fields, it was found that at the initial stage of the explosion, “hot spots” up to 500 pieces/mm2 were recorded on the surface. At a later stage, a plasma layer was formed on the surface of the conductor, in which filaments, that is, current channels, were formed. In this work, on the basis of the ecton theory, a model of the development of a surface discharge is constructed. The model makes it possible to estimate, firstly, the magnitude of the current flowing through the surface plasma, and secondly, the thickness of the plasma layer.
Numerical investigation of a high-pressure gas medium preionization by runaway electrons
Authors: Lisenkov V V , Mamontov Yu I , Tikhonov I N
Published: November 2021

A comparative simulation of the generation and acceleration of runaway electrons in the discharge gap during the initiation of the discharge by nanosecond and subnanosecond pulses is carried out. We used a numerical model based on the PIC-MCC method. Calculations were carried out for N2 6 atm pressure. Numerical simulation of a formation process of the electron avalanche initiated by an electron field-emitted from the top of the cathode microspike was carried out taking into account the motion of each electron in the avalanche. Characteristic runaway electron trajectories, runaway electron energy gained during the motion through the discharge gap, times required for runaway electrons to reach the anode were calculated. We compared our results with calculations using well-known differential equation of electron acceleration using braking force in Bethe approximation. We solved this equation also for braking force based on real (experimental) ionization cross section. The reasons for the discrepancy in the calculation results are discussed.
Simulation of negative corona discharge in atmospheric air: from mode of Trichel pulses to stationary discharge
Authors: Kokovin A O , Kozyrev A V , Kozhevnikov V Yu
Published: November 2021

The paper presents a 2D multi-fluid non-stationary model of a negative corona discharge in atmospheric-pressure air in the needle-to-plane diode. Discharges were simulated in gaps up to 1 cm with an applied voltage in the range of 8-100 kV. The simulation results demonstrate two stages of the discharge evolution: a pulsed-periodic stage called the Trichel pulses mode and a stationary glow discharge mode. The spatio-temporal distributions of the discharge plasma and electric field are shown in detail. Physical mechanism of Trichel pulses formation and transition to the stationary discharge are also revealed. The duration of the Trichel pulse mode gradually decreases with increasing of the applied voltage.
The problem of “anomalous” ion transport in high-current vacuum discharges
Authors: Kozhevnikov V Y , Kozyrev A V , Kokovin A O
Published: November 2021

This paper gives an exhaustive theoretical description of the so-called “anomalous” ion transport phenomenon that exists in vacuum diodes with cathode plasma emission. The phenomenon is represented by the cathode plasma directed movement towards anode. In general terms, the “anomality” means that metal ions are accelerated towards an electrode with a higher electrostatic potential (anode). The theoretical description is given within the framework of a one-dimensional kinetic model, which is based on the Vlasov-Poisson system of equations for plasma and electrostatic field components. Time-dependent accurate numerical solution of this system describes the process evolution leading to “anomalous” ion transport. It was shown that the “anomalous” transport has fast electrodynamic nature.
Formation of volume discharges in dense gases at pulse repetition rates up to 10 kHz
Authors: Kozlov B A
Published: November 2021

Abstact

It is shown that for the formation of stable volume discharges at pulse repetition frequencies up to 10 kHz and more, it is recommended to use sectioning of the discharge gap with subsequent excitation of discharges in each section from an autonomous pulse generator. The role of an autonomous pulse generator can also be performed by an auxiliary circuit that directs the necessary part of the energy stored in the main energy storage of a pulse generator with only a single switch to an individual discharge gaps. The description and results of the study of one of these variants of a partitioned discharge gap and a pulse generator are given. Pumping energy densities of 100–150 mJ-cm−3 at pulse repetition frequencies up to 8 kHz in CO2 laser mixtures and 80–100 mJ-cm−3 in N2-Ne and Xe–Ne mixtures at pulse repetition frequencies up to 10 kHz were achieved.
Electric explosion of flat copper conductors in asymmetric and symmetric configurations in the current skinning mode
Authors: Labetskaya N A , Datsko I M , Chaikovsky S A , Vankevich V A , Oreshkin E V , Oreshkin V I
Published: November 2021

Plasma formation on the surface of conductors as a result of a skin explosion is one of the key issues of the efficiency of energy transportation along the vacuum lines of terawatt-level pulsed generators. Experimental studies of plasma formation on the surface of flat conductors were carried out on the MIG generator (current level ~ 2.5 MA, rise time ~ 100 ns). The magnitude of the magnetic field induction exceeded the values required for the explosion of the conductor surface facing the magnetic field in an asymmetric configuration or both surfaces of the conductor in a symmetric configuration. It was shown that in both configurations, a plasma channel is formed on the surface of a copper foil with a thickness of 100 microns along its longitudinal axis. Experimental data on the dynamics of plasma formation at the edges of a flat conductor have been obtained. A magnetohydrodynamic simulation of an explosion in strong magnetic fields of flat conductors whose width is much greater than their thickness showed that: the expansion of the plasma along the width of the conductor is suppressed, and the plasma expands mainly along its thickness. The simulation results are in good agreement with the experimental once.
On hybrid type of cathode attachment in high current vacuum arcs
Authors: Shmelev D L , Chaikovsky S A , Uimanov I V
Published: November 2021

This paper discusses the issues of a possible change of the type of cathode attachment of high-current vacuum arcs (HCVA) with an average cathode current density of more than 105 A/cm2. This type of HCVA is used as pumping plasma gun in experiments with plasma puff z-pinches. These experiments showed that the measured linear mass of the HCVA plasma jet is much higher (by a factor of 10 or more) than the expected mass, which can be obtained from the assumption that cathode attachment occurs only through a multitude of cathode spots emitting supersonic plasma jets. It is shown that in HCVA of the type under consideration, at some time instant there are two types of cathode attachments - cathode spots and thermionic erosion attachment (TEA). It can be said that HCVA of this type have a hybrid cathodic attachment. Unlike cathode spots, TEA produces a subsonic plasma flow, which contributes to an increase in the linear mass of the HCVA plasma jet.
Time behavior of an electron beam current pulse in the axial and peripheral zones of an anode in vacuum and gas-filled diodes
Authors: Sorokin D A , Lomaev M I , Dyatlov A V , Tarasenko V F
Published: November 2021

The study of the time behavior of a current pulse of an electron beam generated during a high-voltage nanosecond discharge in gas-filled and vacuum diodes has been carried out. As follows from the experimental results, in both cases, the distribution of the beam current density in the plane of a grounded anode is non-uniform. The highest beam current density is recorded in the axial part of the anode. It was established that in the case of a gas-filled diode, ~ 2 ns after the onset of the beam current pulse, its shape in the axial anode zone changes relative to that in the peripheral one. It is assumed that the most probable reason for this is the effect of compensation of the charge of the beam electrons by the positive charge of ions arising in the ionization process in the paraxial zone.
Hole size effect on microhollow cathode discharge in air
Authors: Moshkunov S I , Nebogatkin S V , Romanov K I , Shershunova E A
Published: November 2021

In this work the values of main electrical parameters of the microhollow cathode discharge in atmospheric air (peak discharge current, discharge ignition voltage) depending on the diameter of the hole in the cathode were obtained. It was experimentally found that at currents up to 2 mA, the discharge operated in a self-pulsing mode. According to the experimental results it was concluded that the value of the discharge ignition voltage at average discharge current exceeding 2 mA didn’t depend on the hole diameter.
Runaway of electrons and initiation of explosive electron emission during pulse breakdown of high-pressure gases
Authors: Mesyats G A , Zubarev N M
Published: November 2021

We propose a scenario of the initiation of explosive electron emission on the boundary of the electrode and a high-pressure gas. According to this scenario, positive ions are formed due to the gas ionization by field-emission electrons and accumulated in the vicinity of protrusions of micron size at the cathode. The distance between the ion cloud and the emitting surface decreases with increasing pressure which results in a growth of the local field. As a consequence, an explosive growth of the emission current density occurs for a dense gas (the gas with the pressure of tens of atm). As a result, explosive-emission centers can be formed in dozens of ps. These centers give a start to plasma channels expanding towards the anode. Runaway electron flow generated near the channel heads ionizes the gas gap, causing its subnanosecond breakdown.
Experimental installation for studying cathode plasma processes in vacuum gap of pulsed electron accelerator with gas or liquid injection
Authors: Egorov I S , Klimkin A V , Poloskov A V , Serebrennikov M A , Trigub M V
Published: November 2021

One of the directions of using plasma sources is the formation of plasma emitters for electron beams as part of direct-action charged particle accelerators. The parameters of the accelerator generators require mutual matching with the characteristics of the plasma emitters. The paper describes the design, composition and diagnostic equipment of an experimental stand based on a vacuum chamber of a pulsed electron accelerator for testing plasma sources of pulsed electron beams. The stand includes a vacuum volume with a high-voltage bushing, pumping out pipes, diagnostic windows along the perimeter and a mounting flange of a complex device for diagnosing the characteristics of pulsed electron beams. The stand provides the possibility of controlled supply of gas and liquid to the formation region of the plasma emitter of electrons under the influence of an accelerating voltage pulse. The location of the diagnostic windows and flanges of the stand allows direct optical observations of the plasma formation region in the frontal and profile directions. The use of the stand will make it possible to determine the characteristics of the tested plasma emitters for their operation as part of a vacuum diode of pulsed electron accelerator.
Magnetic field influence on the Penning discharge characteristics
Authors: Mamedov N V , Rohmanenkov A S , Solodovnikov A A
Published: November 2021

In this work characteristics of pulsed penning ion source for miniature linear accelerators was investigated by experimental measurements and PIC (Particle-In-Cell) simulations. The paper presents dependences of the discharge current and extracted current on intensities of the uniform magnetic field for different pressure. Also, typical examples of the current pulse waveforms obtained by PIC simulation and experiment for different magnetic field are presented. The simulated electron and ion distributions inside discharge gap give qualitative explanation of the experimentally observed fluctuations in current pulses. These current fluctuations arise as a result of the violation of the electric field axial symmetry due to the electron spoke movement of the towards the anode.
Generation of plasma in low-pressure discharge
Authors: Nikulin S P
Published: November 2021

A hydrodynamic model of plasma has been developed, which takes into account both secondary and primary electrons. It has been shown that a solution with a plasma potential higher than the anode potential is possible if the ionization frequency is higher than some critical value. At lower ionization frequencies, it is possible to obtain a solution with a plasma potential below the anode potential
Multi-cycle of AISI 5135 steel modification by irradiation of the “film (Si (0.2 μm) + Nb (0.2 μm))/(AISI 5135 steel) substrate” system with an intense pulsed electron beam
Authors: Koval N N , Ivanov Yu F , Shugurov V V , Teresov A D , Petrikova E A
Published: November 2021

Steel AISI 5135 surface layer modification carried out by high-cycle high-speed melting of the “film (Si + Nb)/(steel AISI 5135) substrate” system with an intense pulsed electron beam with an impact area of several square centimeters, have been implemented in a single vacuum cycle on the “COMPLEX” setup. The regime of the system “film (Si (0.2 μm) + Nb (0.2 μm))/(steel AISI 5135) substrate” irradiation with an intense pulsed electron beam (20 J/cm2, 200 μs, 3 pulses, 3 cycles) which makes it possible to form a surface layer with high thermal stability have been revealed. This layer is characterized by high hardness, more than 3 times higher than the hardness of AISI 5135 steel in the original (ferrite-pearlite structure) and wear resistance, more than 90 times higher than the wear resistance of the initial AISI 5135 steel. It is shown that the high strength and tribological properties of steel are due to the formation of the hardening phase particles (niobium silicide of Nb5Si3 composition).
Charge and elemental composition of plasma generated by sputtering of powder target from amorphous boron
Authors: Ivanov Y F , Shugurov V V , Krysina O V , Prokopiev V E
Published: November 2021

One of the effective and widespread methods of surface hardening of metal products is an ion-plasma saturation of the surface of machine parts and mechanisms with various elements (nitrogen, oxygen, carbon). Less investigated method is the process of ion-plasma saturation of the metals and alloys surface with boron. The purpose of the present work is to develop a method for the formation and study of parameters (electron temperature, plasma potential and concentration), elemental and charge composition of plasma generated at sputtering of a target from amorphous boron powder. To achieve the stated goal, a discharge system with a hot anode made of powder boron, as well as a pulse arc evaporator with a hot cathode made of sintered boron powder, was developed, designed, created and tested. Charge and elemental composition of boron-containing plasma generated during powder target sputtering from amorphous boron are defined by optical spectrometry method. It is shown that the generated plasma contains mainly neutral atoms and single-charge boron ions, as well as iron, silicon, copper and argon particles.
Development of the computer model of the plasma installation
Authors: Okulov R A , Popov E V , Gelchinsky B R , Rempel A A
Published: November 2021

Mathematical model of a plasma installation for the production of metal powder and coating has been developed. The problem of creating an objective mathematical model of the plasma jet flow is solved, which adequately describes the real process and allows predicting the parameters of the plasma jet. The value of the temperature of the plasma jet at a characteristic point located on its axis is investigated. The computer model was verified by carrying out a full-scale experiment. Comparative analysis of the results of numerical and field experiments showed satisfactory convergence. It is shown that the temperature of the plasma jet flow obeys the normal Gaussian distribution. The research results can be used to improve processes and technological equipment.
Investigation of the plasma composition of a discharge with a self-heating hollow cathode and an active anode in a gas mixture with titanium and hexamethyldisilazane vapors
Authors: Menshakov A I , Bruhanova Yu A , Surkov Yu S , Skorynina P A
Published: November 2021

The analysis of composition of low-pressure (~0.1-1 mTorr) hollow cathode arc plasma in Ar+N2 gas mixture with Ti+hexamethyldisilazane vapors was carried out by optical emission spectroscopy. The influence of HMDS flow rate (1-10 g/h), discharge current (10-50 A) and Ti-vapors flow on hexamethyldisilazane decomposition degree and plasma composition and was investigated. The proposed plasma activation method provides both an intense flow and a high activation degree of metal vapors, and a sufficient decomposition degree of precursor vapors for the formation of solid TiSiCN coatings at a high deposition rate. Test coatings with a thickness of 6 microns and a hardness of 31 GPa were obtained in 1 hour at 400ºC.
Effect of the O2 dissociation degree on the rate of anodic evaporation of Al in a low-pressure arc
Authors: Kamenetskikh A S , Gavrilov N V , Krivoshapko S V , Tretnikov P V , Chukin A V
Published: November 2021

The results of probe diagnostics and optical emission spectroscopy of Ar-O2 plasma of a low-pressure arc generated under anodic evaporation of Al and an increased (0.32 – 0.48) degree of O2 dissociation are presented. It is shown that an increase in the degree of O2 dissociation at a constant gas flow into the discharge gap leads to a significant (more than 1.5 times) decrease in the density of the evaporated atoms flux and a corresponding decrease in the coating deposition rate. The observed effect is due to the accelerated growth of the oxide film on the melt surface, which leads to the limitation of the flow of evaporated Al atoms by the rate of diffusion through the alumina.
Influence of electron-beam heating modes on the structure of composite ZrO2-Al2O3 ceramics
Authors: Klimov A S , Bakeev I Y , Zenin A A
Published: November 2021

The article presents the results of electron beam sintering of composite ceramics based on Al2O3 and ZrO2 powders. Samples were made with different contents of Al2O3 and ZrO2 components and different pressing pressures. Sintering was carried out in vacuum at a helium pressure of 30 Pa. An electron beam generated by a forevacuum plasma electron source was used for sintering. It is shown that the sintering result depends on the pressing pressure and the percentage of components. The influence of the geometry of the samples and their composition on the temperature drop over their volume during sintering has been determined.
Electron beam sintering of Mn-Zn ferrites using a forevacuum plasma electron source
Authors: Klimov A S , Bakeev I Y , Zenin A A
Published: November 2021

The article presents the results of electron beam sintering without applying pressure of Mn-Zn ferrites in an oxygen environment. Samples for sintering were made from fine powders and pressed at various pressures into compacts in the form of disks. Measurements of the elemental composition and structure of the sample after sintering are presented. It is shown that the result of sintering depends on the pressing pressure of compacts, time and temperature of sintering.
Influence of temperature on tungsten carbide formation in a beam plasma discharge
Authors: Zhanbolatova G K , Baklanov V V , Skakov M K , Sokolov I A , Bukina O S , Kozhahmetov Ye A , Orazgaliev N A
Published: November 2021

This paper presents a method of tungsten surface carbidization using a plasma-beam setup to assess the effect of temperature on the formation of tungsten carbides. Methane was used as a plasma-forming gas. The working gas pressure in the chamber was (1.3–1.4)10−1 Pa. Experiments on the formation of carbides were carried out at different temperatures (700-1000°C). It was recorded that at a temperature of 700°C, crystallization centers of a carbon film appear on the sample surface. With an increase in the irradiation temperature to 800°C and 900°C, the surface of the samples is covered with a continuous carbon film. As a result of the experimental work carried out, it was found that the formation of tungsten semicarbide occurs at 900°C. A further increase in temperature leads to the formation of tungsten monocarbide.
Comparative study on high-voltage nanosecond pulses and dielectric barrier discharge effects on surface morphology and physico-chemical properties of natural pyrrhotite
Authors: Bunin I Zh , Khabarova I A
Published: November 2021

In this paper we used analytical electron microscopy, potentiometric titration (electrode potential), sorption and flotation measurements and other methods to study changes in the surface morphology, electrochemical, and physicochemical properties of the natural pyrrhotite exposed to nonthermal action of the repetitive nanosecond high-power electromagnetic pulses and low-temperature plasma of dielectric barrier discharge in air at atmospheric pressure. As a result of exposure to high-voltage nanosecond pulses, a sharp shift in the electrode potential of pyrrhotite to the region of negative values caused a decrease in the sorption of the anionic collector on the mineral, a decrease in the hydrophobicity of the surface and flotation of the mineral was due to an increase in the content of oxidized ferric iron on the mineral surface. Dielectric barrier discharge treatment caused the shift of the electrode potential to the region of negative values (–60 mV) in the range of pH 9.7-12, which causes the effect of a decrease in the sorption and flotation activity of pyrrhotite. The advantages of using the short-term (10-30 seconds) energy impacts for structural and chemical modification of the surface and physicochemical properties of sulfide minerals of iron are shown.
Effect of ion irradiation on structural state and mechanical properties of naturally-aged hot-pressed D16 (Al-Cu-Mg) alloy profiles
Authors: Gushchina N V , Ovchinnikov V V , Kaigorodova L I , Rasposienko D Y , Vichuzhanin D I
Published: November 2021

The effect of irradiation with 20 keV argon ions on the mechanical properties, structure, and phase composition of quenched and then naturally aged, hot-pressed profiles (6 mm thick) from the D16 alloy of the Al-Cu-Mg system has been studied. It was found that short-term irradiation with Ar+ ions (E = 20 keV, j = 200 μA/cm2, F = 1×1016 cm-2, irradiation time 8 s) leads to transformation of the microstructure and phase composition of the alloy. The coarsening of the initial subgrain structure occurs near the sample surface. Both in the surface layer and at a distance of ∼ 150 μm from it, partial dissolution and fragmentation of complex intermetallic compounds of crystallization origin located along grain boundaries are observed, as well as a decrease in the size and change in the morphology of Al6(Fe, Mn) intermetallic compounds of crystallization origin are observed too: the distribution density of lamellar precipitations decreases, and equiaxial precipitations disappear. Under the influence of irradiation, the decomposition of the supersaturated solid solution is activated with the formation of a more stable phase S’. As a result of ion-beam treatment in this mode, the plasticity of the alloy increases while maintaining the strength properties.
Ion current optimization in a magnetron with tunable magnetic field configuration
Authors: Kaziev A V , Ageychenkov D G , Tumarkin A V , Kolodko D V , Sergeev N S , Kharkov M M , Leonova K A
Published: November 2021

The response of the ion current in the substrate region to the magnetic system configuration of a circular magnetron was studied during direct current sputtering of aluminum target. The unbalancing degree induced by changing of magnets’ positions was modelled with finite element methods. The ion saturation current in the substrate region showed more than twofold variation with unbalancing degree in the range 0.6–1.2. The dependence was non-monotonic, and the system was optimized to maximize the substrate ion current. The Langmuir probe diagnostics showed plasma density ~ 1016 m−3 in the optimized magnetic configuration.
Modification of stainless steel based on synergistic of low-energy high-intensity ion implantation and high-current electron beam impact on the surface layer
Authors: Ryabchikov A I , Korneva O S , Sivin D O , Ivanova A I , Lopatin I V , Bozhko I A
Published: November 2021

The results of experiments on low-energy implantation of AISI 321 stainless steel by nitrogen ions are presented. The treatment was carried out by a pulsed beam of nitrogen ions obtained using a ballistic ion focusing system. The surface modification occurs with the formation of a two-layer structure, which is typical for ion-plasma nitriding processes of stainless steels. The thickness of the modified layer can reach 27 μm after 1 hour of ion-plasma treatment. The influence of subsequent modification of the ion-doped layer by the action on the surface of the pulsed high-current electron beam of microsecond duration is studied. The work presents the results of the studying the regularities of changes in the depth distribution of dopants, microstructure and phase composition of the modified and matrix layers by optical metallography, diffraction analysis and transmission electron microscopy.
Energy density distribution of a modulated electron beam in a source with a plasma cathode based on a low pressure arc
Authors: Shin V I , Moskvin P V , Vorobyov M S , Devyatkov V N , Koval N N
Published: November 2021

The article presents the results of studies devoted to the study of the energy density distribution in the amplitude-modulated regime of electron beam generation. It is shown that in the first ≈ 50 μs of the duration of the beam current pulse, its spatial rearrangement occurs, due to the development of the arc discharge current. Thus, the rearrangement of the arc current, which develops from the axis of the system, leads to an axial diving of the emission current density and the beam current density on the target. With the development of the arc current, the energy density on the target on the axis of the system decreases and after ≈ 50 μs takes on a steady-state value, which can change only as a result of a change in the conditions for generating an electron beam or the transition to a modulated regime of electron beam generation. It has been experimentally shown using calorimetric measurements that the shape of the electron beam current pulse with its amplitude modulation with a pulse duration of more than 100 μs has little effect on the distribution of the beam energy density in the target region.
Formation of a silicon-niobium-based surface alloy using electron-ion-plasma surface engineering
Authors: Shugurov V V , Koval N N , Ivanov Yu F , Teresov A D , Petrikova E A
Published: November 2021

The results of the development and study of the modes of formation of a surface alloy based on silicon and niobium on steel 40X using electron-ion-plasma engineering of the surface are presented. The surface alloy was created in several stages: first, layers of silicon and niobium were deposited successively, and then electron-beam remelting of the surface took place. After that, the samples were subjected to nitriding. The dependences of the change in the surface hardness of the samples on the processing modes are shown. In the optimal processing mode, the surface hardness increased by almost 70 times compared to the original material.
Interaction of plasma with beryllium
Authors: Sokolov’ I A , Skakov M K , Miniyazov A Z , Tulenbergenov T R , Zhanbolatova G K
Published: November 2021

In this work shows some results of studying the microstructure of HP-56 beryllium after plasma irradiation. The experiments revealed a change in the microstructure of beryllium after irradiation with hydrogen, deuterium and helium atoms. The pore diameter and their bulk density increase depending on the plasma parameters.
Effect of the annealing temperature on the structural properties of hafnium nanofilms by magnetron sputtering
Authors: Win Thant Sin , Kuzmenko A P , Rodionov V V , Than Min Myo
Published: November 2021

In this work investigated the effect of the annealing temperature on hafnium nanofilms obtained by DC magnetron sputtering on Si substrates. The nanofilms annealed through 100°C to 700°C by a High-Temperature Strip Heater Chambers (HTK-16N) on an X-ray Diffractometer (XRD). The microstructure and morphology of the films at different temperatures were investigated by XRD, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Raman Microspectrometer (RS). It was found that annealing affects changes in the lattice strains, texture, grain size, and roughness of Hf nanofilms. According to XRD data, the structure of the thin films showed amorphous from room temperature to 100°C and starting from a temperature of 200°C were changed crystallization. At 500°C a monoclinic structure corresponding to hafnium dioxide HfO2was formed in hafnium nanofilms.
Electron-beam deposition of thermoconducting ceramic coatings for microelectronic devices
Authors: Oks’ E M , Tyunkov A V , Yushkov Y G , Zolotukhin D B
Published: November 2021

This paper presents the experimental study of dielectric coatings based on aluminum oxide (Al2O3) and aluminum nitride (AlN) ceramics as applied to their use in microelectronics. It is shown that the coatings obtained by electron-beam evaporation of ceramic in forevacuum pressures (1-100 Pa) endow devices with required dielectric parameters and improves heat sink from the surface of monolithic integral circuits.
Plasma nitriding in complex post-processing of stainless steel parts obtained by additive laser technology
Authors: Makarov A V , Kuznetsov V P , Skorynina P A , Sirosh V A , Vladimirov A B , Lezhnin N V , Kolmakov S V
Published: November 2021

Considered are the prospects of applying complex post-processing for an additive manufactured product with the deposition of a multilayer composite coating [Ti0.2C0.8/a-C]40 at the final stage. It is shown that heat treatment, finish milling, ion-plasma nitriding and burnishing with a sliding diamond indenter of a PH1 steel part obtained by selective laser melting (SLM) before deposition of a thin-film coating provides the coating with a minimum surface roughness Ra = 82-86 nm and a maximum hardness of 25.2 ± 1.4 GPa with an increase in the microhardness of the entire “coating-substrate” system.