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Showing papers in "Plasma Physics Reports in 2020"


Journal ArticleDOI
TL;DR: In this paper, the authors investigate the nonlinear stage of the instability and resulting anomalous electron current using nonlinear Particle-in-Cell simulations and find that the anomalous current is proportional to the applied electric field thus demonstrating constant anomalous mobility.
Abstract: The transverse electron current due to the crossed electric and magnetic fields results in the robust instability driven by the electron $${\mathbf{E}} \times {\mathbf{B}}$$ drift. In the regime of interest for electric propulsion applications, this instability leads to the excitation of quasicoherent nonlinear wave resulting in the anomalous electron transport. We investigate the nonlinear stage of the instability and resulting anomalous electron current using nonlinear Particle-in-Cell simulations. It is found that the anomalous current is proportional to the applied electric field thus demonstrating constant anomalous mobility. Moreover, the scaling of the current density follows the dependence of the dominant resonance wavelength on the electric and magnetic field strength thus clearly demonstrating the cyclotron nature of the instability.

16 citations


Journal ArticleDOI
TL;DR: In this paper, a multispectral optical actinometry method was proposed for the analysis of the penetration of water molecules into the plasma chamber from the cooling circuits of the ITER near-wall plasma.
Abstract: The state-of-art of studies of processes involving small fractions of particles formed as a result of chemical transformations of the source gas or appearing from the outside as an impurity is discussed. Various high-sensitivity methods for measuring the low concentrations of particles are considered. The main focus is on spectral methods, both classical and laser ones. The main modern fields of the application of non-equilibrium plasma, features, and achievements of the diagnostic tools used in them are highlighted. The emphasis is on spectroscopic studies of plasma purity in the low-temperature near-wall layers of thermonuclear reactors. In this case, the issue of the penetration of water molecules into the plasma chamber from the cooling circuits is of particular importance. In view of the limited accessibility to the reactors, new remote versions of spectral emission methods are being developed that are focused on the diagnostics of the ITER near-wall plasma. A new method of multispectral optical actinometry is discussed, in which intermediate chemically unstable particles can play the role of actinometers. This broadens the range of possibilities for quantitative measurements of concentrations of particles of different kinds, and increases the sensitivity. Effective actinometric pairs were found for the objects under consideration, e.g., hydrogen and deuterium atoms. The schemes are worked out on laboratory facilities, and kinetic models of plasma-chemical processes are developed. Scaling of the results of model experiments makes it possible to predict the measurement of the impurity flows at the level (10–9–10–13) Pa m3 s–1 with the localization of sources determined by the spatial resolution of the optical system.

16 citations


Journal ArticleDOI
TL;DR: In this paper, a spark discharge is modeled in a long air gap of atmospheric pressure at a positive voltage with a long front duration, excluding the quasi-continuous development of the leader.
Abstract: A spark discharge is modelled in a long air gap of atmospheric pressure at a positive voltage with a long front duration, excluding the quasi-continuous development of the leader. It is shown that, with a front steepness of less than 30 kV/μs, an ionization wave moves in the gap, whose speed is 2 orders of magnitude slower than the speed of streamers in the streamer zone of the leader. The electric field behind the front of such a wave along the entire length of the formed primary channel is kept within 20–25 kV/cm, providing an electron density of 1011 cm–3 for hundreds of microseconds. The state of the gas in the primary channel changes dramatically with the propagation of a disturbing field effect of a nanosecond in duration. The disturbance range to the head of the primary channel initiates the development of a streamer flash from this head with the initial velocity of ~109 cm/s, which leads to a sharp increase in the brightness of the radiation from the channel. The reason for the amplification of radiation is the active production of electronically excited particles. The gas temperature in the channel does not exceed 1000 K. According to characteristics such as the gas temperature, longitudinal electric field, and electron density, the channel in the step phase of the development of a long spark differs fundamentally from the leader’s channel, which is able to exist and develop only in the quasi-continuous phase.

15 citations


Journal ArticleDOI
TL;DR: In this article, a new type of dust ion-acoustic shock wave related to anomalous dissipation is described, and the main dissipative processes related to charging of dust particles, absorption of ions by dust particles and Coulomb collisions between ions and dust particles are analyzed.
Abstract: Methods of description of ion–acoustic shock waves in dusty plasma are presented. A new type of dust ion–acoustic shock waves related to anomalous dissipation is described. The main dissipative processes related to charging of dust particles, absorption of ions by dust particles, Coulomb collisions between ions and dust particles, and Landau damping are analyzed. Proposed methods of theoretical analysis enable explaining all major specific features of dust ion–acoustic shock waves observed in the laboratory experiments. The shock waves of this type are present in the near-Earth plasma and the universe. Their investigation is possible in active ionospheric experiments of the Fluxus type. Important astrophysical problems in which the appearance of shock waves under consideration should be taken into consideration are the shock waves of supernovas, evolution of Local Interstellar medium, etc.

15 citations


Journal ArticleDOI
TL;DR: In this article, a brief review of the dusty plasma near the surface of the Moon is given, and problems related to theoretical and numerical modeling of the plasma-dust system near the Moon, its experimental investigation, and interpretation of data on near-lunar dusty plasma are formulated.
Abstract: A brief review is given of the dusty plasma near the surface of the Moon. Electrostatic processes represent an important factor of formation of such plasma. Problems related to theoretical and numerical modeling of the plasma–dust system near the Moon, its experimental investigation, and interpretation of data on near-lunar dusty plasma are formulated.

14 citations


Journal ArticleDOI
TL;DR: In this article, the authors consider the presence of two phases of acceleration of charged particles in solar flares in which nonrelativistic electrons and protons are accelerated in the first phase, while relativistic electron and proton are accelerated during the second phase.
Abstract: The solar proton events on September 4–10, 2017 motivated us to reconsider the hypothesis of the presence of two phases of acceleration of charged particles in solar flares in which nonrelativistic electrons are accelerated in the first phase, while relativistic electrons and protons are accelerated during the second phase. According to the data of SOHO/EPHIN (relativistic electrons) and ACS SPI (hard X-rays and protons with energy of >100 MeV), the populations of electrons and protons accelerated at the first and second phases of a flare could be separated in these events near the Earth. The data of observations are indicative of the realization of a stochastic mechanism of acceleration in flares according to which protons and electrons gain energy in many elementary acts, whose duration is much shorter than that of the flare itself. To reconcile the stochastic acceleration process with the existence of two phases in solar flares, it is necessary taking into account the gyrosynchrotron radiation losses of electrons that can be neglected at the first phase. The energy of accelerated protons at the first phase is too low for their detection in the Sun. However, in the second phase, it can reach levels sufficient for detection of nuclear and pion decay gamma lines. In this case, the role of coronal mass ejection consists in (1) involvement of an increasingly larger number of loops in the flare process at altitudes ranging from the chromosphere to the corona; (2) return of the accelerated particles into the flare region; (3) additional acceleration of particles at the shock front; (4) creation of conditions for escaping of particles into the interplanetary space in a wide spatial angle.

11 citations


Journal ArticleDOI
TL;DR: The Globus-M2 as discussed by the authors is a 1-Tesla spherical tokamak with toroidal magnetic field up to 0.73 T and plasma current up to 1.33 MA.
Abstract: Globus-M2—a new 1-Tesla spherical tokamak—was recently launched. The main features and research directions of this machine in scope of fusion–fission reactor development are described. Main results of the first experimental campaign with toroidal magnetic field up to 0.73 T and plasma current up to 0.33 MA are discussed. Significant improvement of the discharge parameters as compared to Globus-M was achieved. Plasma total stored energy higher than 7 kJ was obtained. Energy confinement time increase was consistent with predictions by spherical tokamak scalings. Toroidal Alfven eigenmode-induced losses decrease with increase of plasma current and toroidal magnetic field. For the first time, LHCD with the toroidal wave slowing-down was successfully used at a spherical tokamak.

11 citations


Journal ArticleDOI
TL;DR: In this paper, a method for producing microwave generation in a relativistic magnetically insulated vircator in the under-limit mode of an electron beam was proposed, where repeated or multiple passage of the electron beam of the drift tube is organized.
Abstract: A method is proposed for producing microwave generation in a relativistic magnetically insulated vircator in the under-limit mode of an electron beam. The method is implemented if the repeated or multiple passage of the electron beam of the drift tube is organized. In this case, a virtual cathode is formed in the vircator and the powerful microwave generation occurs. Using the particle-in-cell (PiC) simulation, the microwave producing characteristics of the radiation are calculated upon the re-introduction of the beam into the drift tube and the nonlinear dynamics of the electron beam is studied.

11 citations


Journal ArticleDOI
TL;DR: In this paper, the velocities of the positive and negative streamers in the air at atmospheric pressure are experimentally, theoretically, and computationally studied at the discharge of the needle-plane gap by the nanosecond voltage pulses.
Abstract: The velocities of the positive and negative streamers in the air at atmospheric pressure are experimentally, theoretically, and computationally studied at the discharge of the needle–plane gap by the nanosecond voltage pulses. The data on variation in the streamer’s velocity are obtained, including the data at various amplitudes of the voltage pulses. It is established that the streamer’s velocity varies along its motion and is maximum at the electrode with a small curvature radius and at the planar electrode. It is demonstrated that the character of variation in the computational values of the streamer’s velocity over the gap agrees with the experimental data.

10 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the diffraction phenomenon of EM-plane wave by a non-symmetric plate of finite length under the influence of cold plasma and formulated the Wiener-Hopf equation by boundary value problem related to this model and Fourier transform.
Abstract: The present research article presents the investigation of diffraction phenomenon of EM-plane wave by a non-symmetric plate of finite length under the influence of cold plasma. The Wiener–Hopf equation is formulated by boundary value problem related to this model and Fourier transform. The standard way of Wiener–Hopf procedure is used to tackle the resulting equation. Asymptotic expansion and modified stationary phase method are used to find the result for the diffracted wave by finite plate under the assumption of Neumann boundary conditions in an anisotropic medium. The case of an isotropic medium has been obtained by assigning the particular values to elements of permittivity tensor. The high-frequency signal can be assumed only when very large operating frequency is taken into account as compared to the cyclotron frequency. Various physical parameters for isotropic and anisotropic medium are discussed graphically.

9 citations


Journal ArticleDOI
TL;DR: In this article, the stability of a linear chain of dust particles in an external confining force field is studied, where the particles are located in a plasma with Maxwellian electrons with a directed flow of cold ions.
Abstract: The stability of a linear chain of dust particles in an external confining force field is studied. It is assumed that the particles are located in a plasma with Maxwellian electrons with a directed flow of cold ions. It is shown that the aperiodic instability of doubling the chain period can develop in a subsonic flow together with the instability of coupled waves. The region of the crystal stability in the space of external parameters is constructed.

Journal ArticleDOI
TL;DR: In this paper, the formation and evolution of a density bump in an electrostatic shock wave during decay of a discontinuity in a plasma characterized by the presence of hot electrons and a large drop in plasma density across the discontinuity are investigated.
Abstract: Formation and evolution of a density bump in an electrostatic shock wave during decay of a discontinuity in a plasma characterized by the presence of hot electrons and a large drop in plasma density across the discontinuity are investigated. Numerical particle-in-cell simulation in a wide range of plasma parameters revealed that the appearance of the density bump as a result of the action of the electric field of high-energy electrons in the region of the travelling shock front changes the character of generated ion–acoustic waves and is accompanied by complex nonlaminar kinetics of different fractions of accelerated and thermal ions, including those reflected from the front. Investigation of particle trajectories in real and phase spaces unveiled that ions on both sides of the discontinuity, namely, ions of the rarefied plasma captured by the wave and accelerated ions of the dense plasma catching it up, participate in formation and sustaining of the density bump in the shock wave. A qualitative analysis of contributions of both ion components to the density bump is carried out, and specific features of the latter for typical parameters of laser plasma are found.

Journal ArticleDOI
TL;DR: In this paper, the shape of the electron temperature profiles measured in experiments on the axial ECR heating at the L-2M stellarator at different densities and heating powers was analyzed.
Abstract: The shape is analyzed of the electron temperature profiles measured in experiments on the axial ECR heating at the L-2M stellarator at different densities and heating powers. It is ascertained that when the reduced ECR heating power exceeds some threshold value, the electron temperature profiles become broadened and flat in the core region of the plasma column. The correlation is revealed between the appearances of the flat temperature profiles and the density profiles with a dip in the axial region (the dip-shaped profiles) occurring as a result of the density pump-out effect. It is concluded that the appearance of the dip-shaped density profiles in the plasma results in a change in the mechanism of microwave radiation absorption. Hypothetically, the cyclotron absorption of the electron Bernstein waves becomes the dominant mechanism for the microwave radiation absorption that, in turn, results in the formation of the broad and flat (in the core region) electron temperature profiles.

Journal ArticleDOI
TL;DR: In this paper, a theoretical investigation has been made on modulational instability and dust-acoustic rogue waves (DARWs) in a four-component dusty plasma medium containing inertial negatively charged massive heavy (light) cold (hot) dust grains as well as super-thermal electrons and nonthermal ions.
Abstract: A theoretical investigation has been made on modulational instability (MI) and dust-acoustic (DA) rogue waves (DARWs) in a four-component dusty plasma medium containing inertial negatively charged massive heavy (light) cold (hot) dust grains as well as super-thermal electrons and non-thermal ions. The reductive perturbation method is used to derive the nonlinear Schrodinger equation, and two types of modes, namely fast and slow DA modes, have been observed. The conditions for the MI and the formation of associated DARWs are found to be significantly modified by the effects of non-thermality of ions (α), super-thermality of electrons (κ), density-ratio of non-thermal ion to cold dust ($${{\mu }_{i}}$$), and mass-ratio of cold dust to hot dust (σ), etc. The implications of our current investigation in space and laboratory plasmas are briefly discussed.

Journal ArticleDOI
TL;DR: In this article, a modified version of the Lee Model Code with better calculation of the magnetic field inside the Dense Plasma Focus (DPF) tube has been used to investigate the NiZn ferrite effect on the Amirkabir plasma focus (APF) machine behavior.
Abstract: A modified version of the Lee Model Code with better calculation of the magnetic field inside the Dense Plasma Focus (DPF) tube has been used to investigate the NiZn ferrite effect on the Amirkabir Plasma Focus (APF) machine behavior. It has been explained how various lengths of the ferrite can affect the discharge current trace.The minimum ferrite length which had sensible effects on APF working in 10 kV filled with 0.1-Torr argon has been determined. Regarding the optimum conditions for energy-transfer and argon Soft X-Ray (SXR) emission, the optimum length of the NiZn ferrite has been calculated for various charging voltages and pressures and a scaling-law curve has been presented. Measurements have proved increase in the SXR emission by employing ferrites.

Journal ArticleDOI
TL;DR: In this article, the effect of an unequal plasma glow discharge at atmospheric pressure on the surface properties of seeds of grain crops was studied, and it was shown that plasma treatment allows significant improvement of the contact properties of the surface of the seed and that significantly low values of contact wetting angle scan can be obtained.
Abstract: The effect of an glow discharge at atmospheric pressure on the surface properties of seeds of grain crops was studied. It was shown that plasma treatment allows significant improvement of the contact properties of the surface of the seed and that significantly low values of contact wetting angle scan be obtained. The effect on the seed membrane of an unequal plasma glow discharge at atmospheric pressure leads to modification of the surface of the seed, which consists in the development of a fine-mesh network on the surface of the seed. With an increase in exposure time or discharge power, the etching effect on the surface of the seed increases, while the seed germination rate does not increase with the intensification of the processing parameters.

Journal ArticleDOI
TL;DR: In this article, the characteristics of a slow ionization wave arising at the initial stage of breakdown in a long discharge tube under reduced pressure were studied, and the velocity and the time dependence of the intensities of the Ar, Ar+, and Hg lines in the IW at different distances from the high-voltage electrode were measured.
Abstract: The paper presents the results of studying the characteristics of a slow ionization wave (IW) arising at the initial stage of breakdown in a long discharge tube under reduced pressure. The discharge tube is a Philips TUV-30W mercury lamp with an electrode spacing of 80 cm and an inner diameter of 23 mm. The tube is filled with argon at a pressure of 2–4 Torr (nominal data) and mercury vapor. One of the electrodes is grounded, and, to the second one, positive or negative voltage pulses with an amplitude of 2 kV, a leading edge duration of ≈0.5 μs, and a repetition frequency of 1 Hz are applied. The IW velocity and the time dependence of the intensities of the Ar, Ar+, and Hg lines in the IW at different distances from the high-voltage electrode are measured. It is shown that the velocity of a positive IW (3 × 107–5 × 107 cm/s) is higher than the velocity of a negative IW (1 × 107–1.8 × 107 cm/s). The magnitude of the electric field in the front of an IW is evaluated from the comparison of the measured and calculated intensity ratios of the Ar, Ar+, and Hg lines. It is shown that, in a positive IW, the magnitude of the reduced electric field (260–450 Td) is noticeably larger than in a negative one (120–165 Td).

Journal ArticleDOI
TL;DR: In this article, a system of shallow-water equations for rotating stratified plasma in an external magnetic field was obtained in the beta-plane approximation, and the existence of parametric instabilities was demonstrated and their increments were found.
Abstract: Rotating magnetohydrodynamic flows of a thin stratified plasma layer in a gravitational field with a free boundary in an external vertical magnetic field were investigated. Magnetohydrodynamic equations were obtained in the two-layer shallow-water approximation in an external magnetic field when plasma is divided into two layers of different densities. A system of shallow-water equations for rotating stratified plasma in an external magnetic field was obtained in the beta-plane approximation. A linear theory was developed, and solutions in the form of magnetic Rossby waves, along with corrections that describe the effects of stratification, were obtained for stationary solutions in the form of vertical or horizontal magnetic field. Qualitative analysis of dispersion curves reveals the presence of three-wave nonlinear interactions of magnetic Rossby waves for each of the stationary states. The existence of parametric instabilities was demonstrated and their increments were found.

Journal ArticleDOI
TL;DR: In this paper, an experimental study of hybrid X-pinches (HXPs) as sources of vacuum ultraviolet (VUV) radiation within the wavelength range of λ < 2000 A is presented.
Abstract: The results of an experimental study of hybrid X-pinches (HXPs) as sources of vacuum ultraviolet (VUV) radiation within the wavelength range of λ < 2000 A are presented. A KING compact low-voltage generator (45 kV, 200 kA, 190 ns) was used to feed the X-pinches. The dynamics of forming the radiating plasma of HXPs of different materials were studied using pinhole cameras with radiation receivers based on microchannel plates with a time resolution of 5 ns and a spatial resolution of 150 µm. The time structure and energy characteristics of the radiation were studied using diamond photoconducting detectors (PCDs). The spectral composition of UV radiation was investigated using a spectrograph based on the transmission grating. It has been shown that the efficiency of conversion of the capacitor-stored energy to the VUV radiation may reach 5%, whereas the fraction of soft X-rays (SXR) with quanta energies above 800 eV is no more than 3%. In this case, the source brightness reaches 2 × 109 W/(sr cm2).

Journal ArticleDOI
TL;DR: In this paper, a review is devoted to studies of the processes and mechanisms of ignition of a glow discharge in tubes whose length significantly exceeds their diameter (long discharge tubes) at low pressures (~10 Torr and lower) and moderate voltage rise rates (~1 kV/μs and lower).
Abstract: The review is devoted to studies of the processes and mechanisms of ignition of a glow discharge in tubes whose length significantly exceeds their diameter (long discharge tubes) at low pressures (~10 Torr and lower) and moderate voltage rise rates (~1 kV/μs and lower). The electric field in such tubes before a breakdown is substantially nonuniform. Therefore, a breakdown occurs after an ionization wave (or waves) passes through the discharge gap at a speed of ~105–107 cm/s. This makes the characteristics of the breakdown in long tubes significantly different from the breakdown between large and closely spaced electrodes, where the electric field is uniform before the breakdown and where the Townsend or, under strong overvoltage, streamer mechanism is realized. On the other hand, the nature of these processes is very different from those occurring in nanosecond discharges, which arise at voltages with a steepness of ~1 kV/ns and higher and are associated with high-speed (~109 cm/s) ionization waves. The review is based on the materials of experimental and computational works published from 1938 to 2020. Breakdown processes, optical and electrical characteristics of the discharge gap during breakdown, and the influence of the external circuit parameters and external actions (shielding and illumination by external sources of visible radiation) are analyzed.

Journal ArticleDOI
TL;DR: In this paper, the dispersion curves for even and odd surface waves in a three-layer structure (sheath-plasma-sheath) surrounded by metal boundaries are calculated within the framework of the matrix model.
Abstract: Electrodynamic properties of a low-pressure (electron collision frequency much lower than the field frequency) capacitive high-frequency (HF) discharge with large-area electrodes maintained by an electromagnetic field with frequency higher than 13 MHz is studied analytically. The discharge is sustained by surface waves propagating along the plasma–space-charge sheath–metal interface. When describing the sheath, dispersion curves for even and odd surface waves in a three-layer structure (sheath–plasma–sheath) surrounded by metal boundaries are calculated within the framework of the matrix model. It is demonstrated that the field of the fundamental mode (the quasi-TEM mode) must be taken into account for correct discharge impedance calculation in the case of low electron densities, while the field of the surface wave must be taken into account in the case of high electron densities. An approximate expression governing the discharge impedance that is based on accounting only for one mode is derived. The expression is valid at low electron densities when the surface waves are absent, as well as high electron densities exceeding the value giving rise to a geometric resonance in the plasma–sheath system.

Journal ArticleDOI
TL;DR: In this paper, the reductive perturbation method was employed to derive the (3+1)-dimensional cylindrical Korteweg-de Vries (cKdV) equation, which is valid for small but finite amplitude SGASWs.
Abstract: Three-dimensional self-gravito-acoustic solitary waves (SGASWs) in a general (but realistic) self-gravitating degenerate quantum plasma media consisting of heavy nuclei/elements and degenerate electrons are studied. The reductive perturbation method, which is valid for small but finite amplitude SGASWs, is employed to derive the (3+1)-dimensional cylindrical Korteweg–de Vries (cKdV) equation (also known as cylindrical Kadomtsev–Petviashvili equation). To show the parametric regime corresponding to the existence of the localized SGASWs the energy integral equation, which is derived from cKdV equation, is used. Moreover, the effects of the physical parameters on the SGASWs are discussed. The implication of our results for space and laboratory plasmas is briefly discussed.

Journal ArticleDOI
TL;DR: In this paper, the interaction of an additional electron beam with a previously created charged electron plasma of the squeezed state of two counter-propagating superlimiting electron beams in a closed equipotential cavity was studied numerically.
Abstract: The interaction of an additional electron beam with a previously created charged electron plasma of the squeezed state of two counter-propagating superlimiting electron beams in a closed equipotential cavity was studied numerically. The onset of plasma–beam instability in the absence of ions and quasi-linear relaxation is demonstrated. A significant broadening of the EDF towards higher electron energies was established. The considered process can be useful, for example, in electronic traps operating in the electronic string mode and used for generating highly charged ions with their subsequent injection into ion accelerators.

Journal ArticleDOI
TL;DR: In this paper, the stability of a planar plasma crystal in an external confining force field is investigated, where particles are assumed to be located in the plasma with Maxwellian electrons and with a directed flow of cold ions.
Abstract: The stability of a planar plasma crystal in an external confining force field is investigated. Particles are assumed to be located in the plasma with Maxwellian electrons and with a directed flow of cold ions. It is shown that, together with the coupled wave instability, four more types of aperiodic instabilities arise, which lead to the formation of different structures. A region of the crystal stability in the space of external parameters is constructed.

Journal ArticleDOI
TL;DR: In this paper, a Mather-type plasma focus is registered with 1 mm and electron density larger than 1019 cm-3 by the laser sounding methods on a plasma focus with an initial velocity of 2 × 107 cm/s.
Abstract: Plasma bunches with the characteristic size of approximately 1 mm and electron density larger than 1019 cm–3 are registered by the laser sounding methods on a Mather-type plasma focus (PF). The bunches appear after the collapse of the plasma column and move along the discharge axis from the anode with the initial velocity of 2 × 107 cm/s. The generation of these bunches is mainly caused by the axial displacement of the plasma during development of the Rayleigh–Taylor instability on the pinch. The plasma jets in the second half-period of discharge are also registered. Moreover, the layered plasma structures are revealed at the decrease in the discharge current.

Journal ArticleDOI
TL;DR: In this paper, the ion composition of the arc discharge plasma at a consumable hot gadolinium cathode was determined at a discharge current of 50 A, arc voltage ranging from 4 to 14 V, and cathode temperature ranging from 19 to 195 K.
Abstract: The study of a diffuse vacuum arc (DVA) is of interest in connection with the developing methods of plasma processing of the spent nuclear fuel (SNF) This type of discharge can provide a high degree of ionization of the vapors of the cathode material in the absence of droplets and multiply charged ions This work is devoted to the study of the ion composition of the arc discharge plasma at a consumable hot gadolinium cathode by analyzing the optical and mass spectra of ions The plasma ion composition is determined at a discharge current of 50 A, arc voltage ranging from 4 to 14 V, and cathode temperature ranging from 19 to 195 kK The obtained data, together with the data recorded using the condensation probe method, showed that at an arc voltage of 5 to 6 V a plasma is generated with an ionization degree close to 100%, which contains more than 95% of singly charged ions among all the charged states

Journal ArticleDOI
TL;DR: In this article, the authors proposed a mechanism of formation of dusty plasma in meteoroid trails and demonstrated that charging of dust particles of the meteoroid material creates conditions for the appearance of dust acoustic waves.
Abstract: Plasma–dust processes in the Earth’s ionosphere related to transit of meteor bodies and spreading of meteor trail are analyzed. Processes that occur in the meteor trail itself and those taking place in the Earth’s atmosphere upon transit of a meteor body, along with their influence on observers and operation of various technical systems, are investigated. In particular, mechanisms explaining acoustic phenomena accompanying meteor transit during meteor showers are proposed. The mechanism of formation of dusty plasma in meteoroid trails is described. It is demonstrated that charging of dust particles of the meteoroid material creates conditions for the appearance of dust acoustic waves. Dust acoustic perturbations are driven as a result of development of modulation instability of electromagnetic waves emitted by the meteor trail and have frequencies typical of dust sound (0.003–60 Hz). The reports of witnesses revealed that observers on the Earth can hear low-frequency sounds appearing during meteor showers. It is suggested that the sound reaches the Earth’s surface as a result of transfer of oscillations from dust particles to neutrals the concentration of which in the atmosphere is high. The mechanisms of fragmentation of meteor bodies and charging of formed dust particles are analyzed. Characteristic charges of dust fragments for nano- and micrometer-scale particles are estimated. Particles of different shape are considered. The growth rates that give rise to modulation excitation of low-frequency dust acoustic perturbations are calculated. Conditions leading to development of a modulation instability are found.

Journal ArticleDOI
TL;DR: In this article, an analytical solution of the damped KdV equation is derived and the effects of superthermal electrons characterized by the parameter κ and dust-ion collision frequency are found to modify the properties of the DIA solitary waves.
Abstract: Nonlinear propagation of dust-ion-acoustic (DIA) waves in an unmagnetized collisional dusty plasma consisting of superthermal electrons, mobile ions and immobile negative dust particles have been investigated by employing the standard reductive perturbation technique. An analytical solution of the damped Korteweg–de Vries (KdV) equation is derived and the effects of superthermal electrons characterized by the parameter κ and dust-ion collision frequency $${{ u }_{{{\text{id}}}}}$$ are found to modify the properties of the DIA solitary waves. In particular, it has been found that the presence of the superthermal electrons increases the amplitude and also the width of the nonlinear DIA wave. The variation of the amplitude and the width of the DIA wave have been found to be dependent on time. A parametric study of the variation of the electrostatic potential, amplitude, and width of the solitary wave is presented in this investigation.

Journal ArticleDOI
TL;DR: The possibility of the formation of microspherules in plasma-dust processes initiated by meteoroids impacting the lunar surface is discussed in this article, where it is shown that spherules are formed from the material of the melt zone created by a high-speed meteoroid impacting the Moon surface.
Abstract: The possibility of the formation of microspherules in plasma-dust processes initiated by meteoroids impacting the lunar surface is discussed. It is demonstrated that spherules are formed from the material of the melt zone created by a high-speed meteoroid impacting the lunar surface. Initially, they rise above the surface of the Moon and then fall back. It is these spherules that were found in the course of investigation of the lunar soil. Liquid spherules solidify while floating above the surface of the Moon and acquire electric charges as a result of the interaction with electrons and ions, together with the solar radiation, thereby becoming part of the plasma-dust system above the Moon. The concentration of spherules in dusty plasma above the lunar surface and their size distribution are obtained. The upper bound of the spherule size in the distribution is determined by the existence of the upper bound in the statistical data on the size of relatively small meteoroids and amounts to several micrometers. The size of spherules substantially larger than 1 μm corresponds to meteoroids larger than 1 cm. It is impossible to obtain unique statistics with respect to size for large meteoroids. Therefore, it is possible to obtain the size distribution only of spherules of micron and submicron size. The size of meteoroids impacting the lunar surface and creating relatively large spherules can only be estimated. It is demonstrated that the presence of spherules in dusty plasma above the lunar surface can be discovered by piezoelectric sensors during future Luna-25 and Luna-27 missions.

Journal ArticleDOI
TL;DR: In this article, the effects of overtaking collisions of electrostatic multisolitons (i.e., N-solitons) in an electron-hole dense semiconductor plasma are examined employing the reductive perturbation theory (RPT) and Hirota's bilinear method (HBM).
Abstract: The effects of overtaking collisions of electrostatic multisolitons (i.e., N-soliton) in an electron–hole dense semiconductor plasma are examined employing the reductive perturbation theory (RPT) and Hirota’s bilinear method (HBM). A Korteweg-de Vries equation (KdVE), which admits N-soliton, is derived using the RPT. In addition, HBM is applied that resulted in two-soliton and three-soliton solutions. The exchange of energies due to the overtaking collisions between the electrostatic N-soliton are analyzed by varying physical parameters, such as the quantum semiconductor plasma number density and the exchange-correlation terms for electrons and holes, which causes alternation in the behavior of solitons. It is found that the existence of exchange-correlation potentials leads to a diminishing in a phase shift of N-soliton.The current study is an attempt to further exemplify the essential properties of N-soliton in electron–hole plasmas and their applications in the modern semiconductor electronic devices of nanoscale size.