bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract

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

Abstract
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

Abstract
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

Abstract
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.
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

AbstractThis 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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.