Plasma Vortex Research Articles

Dipolar and chain of vortices in quantum plasmas with electrons exchange-correlation effects

The study of linear and nonlinear drift ion acoustic waves in a quantum plasma with electrons exchange correlation and pressure degeneracy effects is presented. A modified linear dispersion relation is obtained for an inhomogeneous degenerate plasma. In the nonlinear regime, dipolar and chain of vortices of drift ion waves are investigated. It is noticed that the amplitude of the dipolar vortices increases as the drift velocity decreases. The present results are compared with the previous studies. The relevance of the research work to laboratory and astrophysical plasmas is also pointed out.

Stable finite element analysis of viscous dusty plasma

PurposeThe purpose of this paper is to provide an analysis of dust acoustic (solitary) waves including viscosity. Specifically, the authors consider a dusty unmagnetized plasma system consisting of negatively charged dust and Boltzmann electrons and ions.Design/methodology/approachIn this paper, a Petrov–Galerkin weak form with upwinding is adopted. Nonlinearity of ion and electron number density in terms of an electrostatic potential is included. A fully implicit time integration is used (backward Euler method), which requires the first derivative of the weak form. A three-field formulation is proposed, with the dust number density, the electrostatic potential and the dust velocity being the unknown fields.FindingsIn this study, two numerical examples are introduced and results show great promise for the proposed formulation as a predictive tool in viscous dusty plasmas. Presence of solitary waves was demonstrated. Dusty plasma vortices are predicted in 2D and 3D, as mentioned in the specialized literature.Research limitations/implicationsWe observed some dependence on step size, which is due to the simple time-stepping scheme. This can be solved with a higher order integration scheme, which implies an added cost to the solution.Practical implicationsDusty plasmas are found in astrophysics (Saturn rings) and electronics industry at several scales and have high impact as a contaminant.Originality/valueTo the authors’ knowledge, this is the first paper with a simulation of dusty plasma including vortices.

High effective heterogeneous plasma vortex reactor for production of heat energy and hydrogen

This work is a continuation of our previous studies [1-10] of physical parameters and properties of a long-lived heterogeneous plasmoid (plasma formation with erosive nanoclusters) created by combined discharge in a high-speed swirl flow. Here interaction of metal nanoclusters with hydrogen atoms is studied in a plasma vortex reactor (PVR) with argon-water steam mixture. Metal nanoclusters were created by nickel cathode’s erosion at combined discharge on. Dissociated hydrogen atoms and ions were obtained in water steam by electric discharge. These hydrogen atoms and ions interacted with metal nanoclusters, which resulted in the creation of a stable plasmoid in a swirl gas flow. This plasmoid has been found to create intensive soft X-ray radiation. Plasma parameters of this plasmoid were measured by optical spectroscopy method. It has been obtained that there is a high non-equilibrium plasmoid: Te > TV >> TR. The measured coefficient of energy performance of this plasmoid is about COP = 2÷10. This extra power release in plasmoid is supposed to be connected with internal excited electrons. The obtained experimental results have proved our suggestion.

Numerical simulation of an argon swirling flow in the presence of a DC discharge

Numerical simulations of the non-stationary three-dimensional swirling Ar flow are presented for plasma vortex reactor (PVR) with a paraxial heat source at various positions of the heat source and electrode forms. Flow and duct parameters correspond to the experimental conditions. Flow velocity and thermal fields have been obtained.

Plasma vortex reactor for production of heat energy and hydrogen

Numerical simulation of the turbulent three-dimensional swirling flow structure in plasma vortex reactor is conducted. Flow and set up parameters correspond to the experimental conditions. Flow velocity and thermal fields have been obtained. A qualitative agreement between the results of the calculations and the experimental data for pure argon has been shown.

Rapid Deposition of Photocatalytically Enhanced TiO<sub>2</sub> Film by Atmospheric SPPS Using Ar/N<sub>2</sub>-Vortex Plasma Jet

Rapid Deposition of Photocatalytically Enhanced TiO<sub>2</sub> Film by Atmospheric SPPS Using Ar/N<sub>2</sub>-Vortex Plasma Jet

Plasma flow disturbances in the magnetospheric plasma sheet during substorm activations

We have considered variations in fields and particle fluxes in the near-Earth plasma sheet on the THEMIS-D satellite together with the auroral dynamics in the satellite-conjugate ionospheric part during two substorm activations on December 19, 2014 with K p = 2. The satellite was at ~8.5RE and MLT = 21.8 in the outer region of captured energetic particles with isotropic ion fluxes near the convection boundary of electrons with an energy of ~10 keV. During substorm activations, the satellite recorded energetic particle injections and magnetic field oscillations with a period of ~90 s. In the satellite-conjugate ionospheric part, the activations were preceded by wavelike disturbances of auroral brightness along the southern azimuthal arc. In the expansion phase of activations, large-scale vortex structures appeared in the structure of auroras. The sudden enhancements of auroral activity (brightening of arcs, auroral breakup, and appearance of NS forms) coincided with moments of local magnetic field dipolarization and an increase in the amplitude Pi2 of pulsations of the Bz component of the magnetic field on the satellite. Approximately 30–50 s before these moments, the magnetosphere was characterized by an increased rate of plasma flow in the radial direction, which initiated the formation of plasma vortices. The auroral activation delays relative to the times when plasma vortices appear in the magnetosphere decreased with decreasing latitude of the satellite projection. The plasma vortices in the magnetosphere are assumed to be responsible for the observed auroral vortex structures and the manifestation of the hybrid vortex instability (or shear flow ballooning instability) that develops in the equatorial magnetospheric plane in the presence of a shear plasma flow in the region of strong pressure gradients in the Earthward direction.

Investigation of electrode erosion products of alternating current plasma torch operating on mixture of steam, carbon dioxide, methane and carbon tetrachloride

The most important unit of the plasma torch mainly subjected to the thermal load of the electric arc is electrode. Tungsten, hafnium, yttrium, aluminum, copper, iron and their alloys are used as electrode materials depending on the plasma-forming gas. Copper-based alloys can be rationally used for gases containing oxygen. The experiments were performed on the three-phase alternating current vortex plasma torch with power of 120 kW working on a mixture of steam, carbon dioxide, methane and carbon tetrachloride for the following flow rates 2.9 g/s, 2.9 g/s, 1.21 g/s and 2.44 g/s respectively. The material of erosion of copper rod electrodes was sampled from water-cooled walls of electric arc plasma torch channels made of stainless steel. The sample was divided into magnetized and non-magnetic parts. According to the energy-dispersive elemental analysis the products of electrode erosion contain oxides and chlorides of copper and iron, as well as metallic copper and iron.

Creation of twisted terahertz carrying orbital angular momentum via stimulated Raman scattering in a plasma vortex

Here, a scheme for the generation of twisted terahertz radiation in a plasma vortex with a helical structure is proposed. Based on stimulated Raman scattering, the incident laser decays into the Langmuir wave. Beating the Langmuir wave with the plasma wave of the media causes the production of current density. The current density can excite twisted radiation at the terahertz frequency. For an incident laser with Gaussian envelops, the orbital angular momentum of terahertz radiation is provoked by the helicity of the plasma vortex. Furthermore, for the Laguerre–Gaussian laser, the orbital angular momentum of terahertz radiation is equal to the difference between the topological charge of the lasers and the electron plasma vortex.

Nonlinear Electrostatic Waves in PIE and PI Plasmas With Field-Aligned Shear Flow

Nonlinear low-frequency ion acoustic (IA) wave and pair plasma convective cell (PPCC) mode are investigated in pair-ion (PI) plasmas with and without electrons in the presence of sheared flows. IA wave forms both KdV solitons and dipolar vortices in PI-electron plasma, and their amplitude depends upon electron density and sheared flow. But when electron density is too low, the structures disappear, because IA does not exist in pure PI plasma. On the other hand, PPCC mode cannot form pulse-type solitary structures in the pair plasma, while it forms dipolar vortices due to finite vorticity. The nonlinear analysis has been performed assuming the presence of electrons in fullerene PI plasma and limit of zero electron density is also considered for a comparison.

Rotation of a single vortex in dusty plasma**Project supported by the National Natural Science Foundation of China (Grant Nos. 11205044 and 11405042), the Program for Young Principal Investigators of Hebei Province, China, the Natural Science Foundation of Hebei University, China (Grant No. 2011JQ04), the NaturalScience Fund for Excellent Young Scholars of Hebei Province, China(Grant No. A2017201099), and the Midwest Universities

A single vortex is obtained in radio-frequency capacitive discharge in argon gas. The dust subsystem is confined in the horizontal plane with an asymmetrical saw structure placed on the lower electrode. The vortex rotates as a whole along the long side of the saw-teeth. Asymmetry of the saw structure plays an important role in the rotation of the vortex. Nonzero curl of the total force resulting from the local ion flow and the electric field in the plasma sheath could be attributed to the persistent rotation of vortex.

Generation of twisted terahertz radiation by transferring orbital angular momentum from static plasma vortex

Here, a new scheme to create a twisted terahertz wave in a static plasma vortex is demonstrated. A static plasma vortex with a helical structure, which is submerged in the static electric field is considered. By propagating lasers in a predominant collisional nonlinearity regime, the nonlinear current density is created at the beating frequency. Based on the transfer orbital angular momentum, three schemes to excite a twisted terahertz radiation are proposed: The creation of twisted terahertz by two Laguerre-Gaussian lasers carrying different orbital angular momenta in the plasma ripple is surveyed. The helicity of terahertz radiation is provoked by the charge numbers of the lasers. In another case, the twisted terahertz generation by Laguerre-Gaussian lasers with similar orbital angular momenta in the static plasma vortex is demonstrated. Finally, even in the absence of a twisted laser, by employing the static plasma vortex, the twisted terahertz radiation can be created. In the last two cases, the helical structure of the static plasma vortex excite the orbital angular momentum of the terahertz.

Polarizability of electrically induced magnetic vortex plasma

Electric field control of magnetic structures, particularly topological defects in magnetoelectric materials, draws a great attention in recent years, which has led to experimental success in creation and manipulation by electric field of single magnetic defects, such as domain walls and skyrmions. In this work we explore a scenario of electric field creation of another type of topological defects -- magnetic vortices and antivortices, which are characteristic for materials with easy plane (XY) symmetry. Each magnetic (anti)vortex in magnetoelectric materials (such as type-II multiferroics) possesses a quantized magnetic and an electric charge, where the former is responsible for interaction between vortices and the latter couples the vortices to electric field. This property of magnetic vortices opens a peculiar possibility of creation of magnetic vortex plasma by non-uniform electric fields. We show that the electric field, created by a cantilever tip, produces a "magnetic atom" with a localized spatially ordered spot of vortices ("nucleus" of the atom) surrounded by antivortices ("electronic shells"). We analytically find the vortex density distribution profile and temperature dependence of polarizability of this structure and confirm it numerically. We show that electric polarizability of the "magnetic atom" depends on temperature as $\alpha \sim 1/T^{1-\eta}$ ($\eta>0$), which is consistent with Euclidean random matrix theory prediction.

27 August 2001 substorm: Preonset phenomena, two main onsets, field‐aligned current systems, and plasma flow channels in the ionosphere and in the magnetosphere

AbstractWe supplement the results of the 27 August 2001 substorm studied earlier in the series of papers. Described is the plasma flow in the nightside ionosphere from the near‐polar region from the polar cap to the auroral oval during the substorm preonset phase and two expansion onsets, EO1 and EO2, produced by reconnection in the closed tail (magnetic reconnection (MR1) and in the open tail lobes (MR2), respectively. We discuss the location of the MR2 region (is it near, middle, and/or distant tail?) and the EO2 trigger mechanism. The upward substorm current wedge field‐aligned current (FAC) and the downward FAC in the polar cap dusk sector that were both produced by different types of magnetosphere‐ionosphere feedback instability are found to provide the main contribution to the system of FACs during EO1 and EO2. Also, we obtain the estimates for the EO1 and EO2 power and energy. Addressed are the variations in the tail lobe magnetic flux and their (variations) association with EO2. In addition, we describe a 3‐D system of mesoscale cells, each of which involves a plasma vortex and a local FAC maximum. The cells of this system in the inner magnetosphere and in the tail lobes intensify one after other within 2 min interval. At last, we substantiate the assumption that the fast plasma flow recorded by the Cluster satellites 7 min prior to EO1 was a bursty bulk flow from the most distant tail.

Semi-Classical theory of Nonlinear interaction of circularly polarized optical vortex beam with plasma channel

A semiclassical approach of nonlinear interaction of intense circularly polarized optical vortex Laguerre-Gaussian (LG) beam modes with a plasma channel is analyzed theoretically and numerically. We study an exchange of angular momentum between the vortex beam and plasma channel. The transfer of angular momentum and the generated magnetic field are calculated. We have observed that both the generated magnetic field and angular momentum transfer depend on beam mode, intensity, and the polarization state of beam mode.

Driven phase space vortices in plasmas with nonextensive velocity distribution

The evolution of chirp-driven electrostatic waves in unmagnetized plasmas is numerically investigated by using a one-dimensional (1D) Vlasov-poisson solver with periodic boundary conditions. The initial velocity distribution of the 1D plasma is assumed to be governed by nonextensive q distribution [C. Tsallis, J. Stat. Phys. 52, 479 (1988)]. For an infinitesimal amplitude of an external drive, we investigate the effects of chirp driven dynamics that leads to the formation of giant phase space vortices (PSV) for both Maxwellian (q = 1) and non-Maxwellian (q≠1) plasmas. For non-Maxwellian plasmas, the formation of giant PSV with multiple extrema and phase velocities is shown to be dependent on the strength of “q”. Novel features such as “shark”-like and transient “honeycomb”-like structures in phase space are discussed. Wherever relevant, we compare our results with previous work.

Experimental observation of self excited co-rotating multiple vortices in a dusty plasma with inhomogeneous plasma background

We report an experimental observation of multiple co-rotating vortices in an extended dust column in the background of an inhomogeneous diffused plasma. An inductively coupled rf discharge is initiated in the background of argon gas in the source region. This plasma was later found to diffuse into the main experimental chamber. A secondary DC glow discharge plasma is produced to introduce dust particles into the plasma volume. These micron-sized poly-disperse dust particles get charged in the background of the DC plasma and are transported by the ambipolar electric field of the diffused plasma. These transported particles are found to be confined in an electrostatic potential well, where the resultant electric field due to the diffused plasma (ambipolar E–field) and glass wall charging (sheath E–field) holds the micron–sized particles against the gravity. Multiple co-rotating (anti–clockwise) dust vortices are observed in the dust cloud for a particular discharge condition. The transition from multiple vortices to a single dust vortex is observed when input rf power is lowered. The occurrence of these vortices is explained on the basis of the charge gradient of dust particles, which is orthogonal to the ion drag force. The charge gradient is a consequence of the plasma inhomogeneity along the dust cloud length. The detailed nature and the reason for multiple vortices are still under investigation through further experiments; however, preliminary qualitative understanding is discussed based on the characteristic scale length of the dust vortex. There is a characteristic size of the vortex in the dusty plasma; therefore, multiple vortices could possibly be formed in an extended dusty plasma with inhomogeneous plasma background. The experimental results on the vortex motion of particles are compared with a theoretical model and are found to be in close agreement.

Force-free foliations

Electromagnetic field configurations with vanishing Lorentz force density are known as force-free and appear in terrestrial, space, and astrophysical plasmas. We explore a general method for finding such configurations based on formulating equations for the field lines rather than the field itself. The basic object becomes a foliation of spacetime or, in the stationary axisymmetric case, of the half-plane. We use this approach to find some new stationary and axisymmetric solutions, one of which could represent a rotating plasma vortex near a magnetic null point.

Flow control for suppression of self-excited rolling oscillation at high angles of attack

A cruciform-finned slender body can excite a limit-cycle rolling oscillation at high angles of attack. To suppress the unwanted motions, flow control approaches should be employed if the aerodynamic control surfaces lose control efficiency at high angles of attack. As a promising technology, the ns-dielectric barrier discharge plasma actuator has been successfully used in high-speed and high-Reynolds-number flow control applications. The present work employs a π-type ns-dielectric barrier discharge plasma actuator and vortex generators to suppress self-excited rolling oscillation at α = 50°. The free-to-roll tests show that the plasma actuator ignited at F+ ∼ 1.5 and that the vortex generators can suppress rolling oscillation. The flow patterns from particle image velocimetry measurement at different cross-sections and rolling angles suggest that the vorticity decrease of the leeward vortices may be the control mechanism for the plasma actuator. For the vortex generators, evident modification of the flow field structure can be observed due to the vortices generated from the vortex generators, which decreases the rolling moment induced by the asymmetry vortices to suppress the self-excited rolling oscillation.

TIME EVOLUTION OF KELVIN–HELMHOLTZ VORTICES ASSOCIATED WITH COLLISIONLESS SHOCKS IN LASER-PRODUCED PLASMAS

ABSTRACT We report experimental results on Kelvin–Helmholtz (KH) instability and resultant vortices in laser-produced plasmas. By irradiating a double plane target with a laser beam, asymmetric counterstreaming plasmas are created. The interaction of the plasmas with different velocities and densities results in the formation of asymmetric shocks, where the shear flow exists along the contact surface and the KH instability is excited. We observe the spatial and temporal evolution of plasmas and shocks with time-resolved diagnostics over several shots. Our results clearly show the evolution of transverse fluctuations, wavelike structures, and circular features, which are interpreted as the KH instability and resultant vortices. The relevant numerical simulations demonstrate the time evolution of KH vortices and show qualitative agreement with experimental results. Shocks, and thus the contact surfaces, are ubiquitous in the universe; our experimental results show general consequences where two plasmas interact.