Motion Of Plasma Particles Research Articles

Modeling plasma particle motion with MATLAB in the physics classroom

Modeling plasma particle motion with MATLAB in the physics classroom

Plasma line detected by Voyager 1 in the interstellar medium: Tips and traps for quasi-thermal noise spectroscopy

The quasi-thermal motion of plasma particles produces electrostatic fluctuations, whose voltage power spectrum induced on electric antennas reveals plasma properties. In weakly magnetised plasmas, the main feature of the spectrum is a line at the plasma frequency – proportional to the square root of the electron density – whose global shape can reveal the electron temperature, while the fine structure reveals the suprathermal electrons. Since it is based on electrostatic waves, quasi-thermal noise spectroscopy (QTN) provides in situ measurements. This method has been successfully used for more than four decades in a large variety of heliosphere environments. Very recently, it has been tentatively applied in the very local interstellar medium (VLISM) to interpret the weak line discovered on board Voyager 1 and in the context of the proposed interstellar probe mission. The present paper shows that the line is still observed in the Voyager Plasma Wave Science data, and concentrates on the main features that distinguish the plasma QTN in the VLISM from that in the heliosphere. We give several tools to interpret it in this medium and highlight the errors arising when it is interpreted without caution, as has recently been done in several publications. We show recent solar wind data, which confirm that the electric field of the QTN line in a weakly magnetised stable plasma is not aligned with the local magnetic field. We explain why the amplitude of the line does not depend on the concentration of suprathermal electrons, and why its observation with a short antenna does not require a kappa electron velocity distribution. Finally, we suggest an origin for the suprathermal electrons producing the QTN and we summarise the properties of the VLISM that could be deduced from an appropriate implementation of QTN spectroscopy on a suitably designed instrument.

Impact of Heavy Ions on the Structure of Current Sheets in the Gravity Field of Exoplanets and Stars

Boundary current sheets (CSs) can be formed in collisionless space plasmas in the environment of exoplanets and cold stars. Usually they represent curved surfaces carrying the electric current analogous to the well-known planetary ionospheres, magnetopauses, or stellar coronas surrounding celestial bodies. At smaller local scales, some of them can be imagined as planar current layers of a finite scale located parallel to the surface of a celestial object and, correspondingly, perpendicular to the direction of the gravitational force. In some cases, this force crossed with magnetic field can influence the dynamics of charged particles in CSs and substantially change the structure of both the current layer and the magnetic field. We have generalized our prior model, taking into account a multi-ion plasma composition and a magnetic field configuration with a shear. It is shown that, due to the drift motion of plasma particles in the crossed gravitational and magnetic fields, the structure of CSs becomes more complex, accruing asymmetric and shifted profiles of the current and plasma densities that depend on dominating current carriers and the characteristics of the magnetic shear. We discuss possible applications of the results to the interpretation of observations of boundary layers in different space plasmas.

THE INFLUENCE OF THERMAL MOTION OF PARTICLES ON THE FORMATION OF CAVITIES IN PLASMA

The effect of the thermal motion of ions and electrons on the formation of plasma density cavities which appear due to inhomogeneous stochastic electric fields is considered. Using the equation of motion of plasma particles in a constant magnetic field and in an inhomogeneous stochastic electric field with a frequency of the order of lower hybrid oscillations, taking into account the thermal motion of particles, the diffusion coefficients and drift velocities of ions and electrons are obtained. These values are used in the Fokker-Planck equation to determine the stationary distribution of the plasma density due to the effect of an inhomogeneous stochastic electric field. The conditions for the thermal velocities of particles under which the formation of a cavity is possible are obtained.

Quantum and Relativistic Effects on the KdV and Envelope Solitons in Ion-Plasma Waves

In this article, we investigate the linear and nonlinear behavior of ion-plasma waves in a two-component plasma containing ions and dust particles. We have studied the linear dispersion characteristics, nonlinear KdV solitons, and amplitude modulated electrostatic waves. Such ion-plasma wave modes in dust-ion plasma have been theoretically investigated by incorporating quantum diffraction and relativistic effects. Numerical analysis of the linear dispersion relation with variations of different parameters has been carried out. By employing the reductive perturbation technique the KdV equation describing the small amplitude solitary profile has been studied. Using the standard multiple scale perturbation method, a nonlinear Schrödinger (NLS) equation has been derived by including quantum and relativistic effects, which describes the nonlinear evolution of the ion-plasma waves in dust-ion plasma. The wave is found to become modulationally unstable beyond certain critical wavenumber. The critical wavenumber and the growth rate of modulational instability are shown to depend significantly on the relativistic motion of plasma particles and the quantum diffraction effect. The results presented in the article are expected to be helpful for understanding the propagation of finite amplitude ion-plasma waves in some laboratory and astrophysical plasma systems. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PACS</i> —52.59.Hq, 67.10.Jn, 52.20 −j, 52.25 −b, 52.30 −d, 52.35 Mw, 52.65 Vv

Effect of Asymmetry Induced by Staggered Angle on the Rectification of Dust Particles in a Dusty Plasma Ratchet

Converting random motion into directional motion of charged dust particles in plasma, i.e., the rectification, can be achieved by using a dusty plasma ratchet, in which the asymmetry of system plays a very important role. Here, we use different staggered angles between the inner and outer gears to control the asymmetry of system and further study experimentally the effect of the asymmetry induced by staggered angle on the rectification of dust particles in a dusty plasma ratchet. Our results show that the spatial distribution and the velocity of dust particles along the saw channel are nonuniform. Decreasing the asymmetry can reduce the flow of dust particle in the saw channel.

Generalized non-ideal treatment and growth rates analysis of drift waves instabilities in a collisions-free magnetized dusty plasma

Dust acoustic wave propagation in weak magnetized homogeneous dusty plasmas has been extensively and successfully studied by different authors. Here, it is analyzed the behavior of electrostatic drift waves of very low frequency, appearing as due to the motion of plasma particles across the static magnetic field and the inhomogeneity introduced by the distribution of the particles in the dusty plasma generating the well-known diamagnetic effect. To study this situation, the kinetic Vlasov model in plasmas will be used. However, these models tend to behave unstably driven by the quasi-equilibrium of the diamagnetic current arising by the heavier species of dusty plasma particles. While other authors have used a standard state equation, such as the Van der Waals one, here, a more accurate model has been chosen as the equation of Ree and Hoover, a state equation that can be considered as a new form of the state equation. Together with the multipole approximation of the dispersion function, Z53 [P. Martin et al., J. Math. Phys. 21, 280–283 (1980)] allows a new derivation to obtain the simplest form of the dispersion relation in the form of a polynomial with complex coefficients. This mathematical approach was realized successfully and allowed straightforward calculus of the growth rate due to the drift unstable mode. This problem has been extensively analyzed in this work, including the non-ideal effect of dusty plasmas. These unstable modes are well discriminated and plotted as a function of the density of the grains in dusty plasma and their radius. Temperature gradients and charge fluctuation have been ignored.

Rationalization of plasma piston’s particles parameters in a coaxial railgun

This article is devoted to collisionless plasma particle motion in a coaxial railgun bore. Numerical modeling results showed that 2 types of motion can be realized in this system. Plasma particle parameters such as mass and charge were rationalized according to the types of motion and their roles in throwing body acceleration. The most effective parameters of the whole system were obtained.

A splitting Fourier pseudospectral method for Vlasov–Poisson–Fokker–Planck system

In this paper, we propose a splitting Fourier pseudospectral method for Vlasov–Poisson–Fokker–Planck (VPFP) system, which describes the motion of charged particles in plasma. The numerical integration for the system is performed by employing the splitting method in time, Fourier Galerkin method in space direction, and Fourier collocation method in phase direction, respectively. The algorithm has spectral accuracy in both space and phase directions and can be implemented efficiently with the fast Fourier transform and technique of diagonalization, respectively. Extensive numerical results in one-dimensional phase space (or 1x×1v) from the proposed numerical method are shown and have proven the good agreement with the theory and previous studies. Numerical algorithm for the VPFP system in two-dimensional phase space (or 2x×2v) has been summarized in Appendix.

The Generalized Nonlinear Ohm's Law: How a Strong Electric Field Influences Nonideal MHD Effects in Dusty Protoplanetary Disks

Abstract The magnetohydrodynamics (MHD) of protoplanetary disks are strongly subject to the nonideal MHD effects arising from the low ionization fraction of the disk gas. A strong electric field induced by gas motions can heat ionized gas particles and can thereby affect the ionization balance in the disks. Our previous studies revealed that in dusty protoplanetary disks, the ohmic conductivity decreases with increasing electric field strength until the electrical breakdown of the disk gas occurs. In this study, we extend our previous work to more general cases where both electric and magnetic fields affect the motion of plasma particles, allowing us to study the impacts of plasma heating on all nonideal MHD effects: ohmic, Hall, and ambipolar diffusion. We find that the upper limit on the electric current we previously derived applies even in the presence of magnetic fields. Although the Hall and ambipolar resistivities can either increase or decrease with electric field strength depending on the abundance of charged dust grains, the ohmic resistivity always increases with electric field strength. An order-of-magnitude estimate suggests that a large-scale electric current generated by gas motions in the inner part of protoplanetary disks could exceed the upper limit. This implies that MHD motions of the inner disk, such as the motion driven by the Hall-shear instability, could either get suppressed or trigger electrical breakdown (lightning discharge). This may have important implications for gas accretion and chondrule formation in the inner part of protoplanetary disks.

Three-dimensional effect of particle motion on plasma filament dynamics

It is shown for the first time with the three-dimensional (3D) electrostatic particle-in-cell simulation that the plasma particle motion influences plasma filament dynamics three-dimensionally. If we assume that the filament size on the cross section is a few times as large as ρemi/me and that the ion temperature is higher than the electron temperature, the poloidal symmetry of filament propagation is broken and the propagation velocity has the non-negligible poloidal component, where ρe is the electron Larmor radius. Then, it is observed that such propagation dynamics depend on the position on the magnetic field line, i.e., in the toroidal direction. As the ion temperature increases beyond the electron temperature, the perpendicular electric field in a filament varies greatly according to the toroidal position. Such a variation might arise from the presheath potential drop on the potential hill side in a filament. Thus, the toroidal dependence of the propagation dynamics appears.

A fast and accurate numerical implementation of the envelope model for laser–plasma dynamics

In laser-driven, plasma wakefield acceleration regimes (LWFA), when relevant scale lengths of the laser envelope and of the driven plasma waves are well separated from the wavelength and frequency of the laser fast oscillating component, a reduced physical model (usually referred to as the envelope model), has been introduced, allowing to formulate the laser–plasma equations in terms of laser cycle-averaged dynamical variables. As a main consequence, physical regimes where this reduced model applies, can be investigated with significant savings of computational resources still assuring comparable accuracy, with respect to standard Particle-In-Cell (PIC) models where all relevant space–time scales have to be resolved.Here we propose a computational framework characterized by two previously unexplored numerical implementations of the envelope model. The first one is based on explicit second order leapfrog integration of the exact wave equation for laser pulse propagation in a laboratory coordinate system in 3D cartesian geometry, replacing the usually quoted representation in an Eulerian frame moving at the speed of light. Since the laser and driven wakefield wave equations in a laboratory frame are advection dominated, we introduce a proper modification of finite differences approximating longitudinal space derivatives, to minimize dispersive numerical errors coming from the discretized advection operators. The proposed implementation, avoiding semi-implicit procedures otherwise required when dealing with a comoving frame, assures significant saving in computational time and ease of implementation for parallel platforms. The associated equation of motion for plasma particles has been integrated, as in standard PIC codes, using the Boris pusher, properly extended to take into account the specific form of the Lorentz force in the envelope model.As a second contribution, a novel numerical implementation of the plasma dynamics equations in the cold-fluid approximation, is presented. The scheme is based on the second-order one-step Adams–Bashforth time integrator coupled to upwind non-oscillatory WENO reconstruction for discretized space derivatives. The proposed integration scheme for the Eulerian fluid equations is equivalent to a leapfrog scheme with an added higher order dissipative truncation errors. It can be used either as a much faster, yet of comparable accuracy, alternative to the PIC representation of plasma particle motion, or even in a hybrid fluid–particle combination when kinetic effects and particle injection and acceleration in a wakefield have to be investigated.

Microscopic Effect on Filamentary Coherent Structure Dynamics in Boundary Layer Plasmas

This study has demonstrated kinetic behaviors on the plasma filament propagation with the three-dimensional (3D) Particle-in-Cell (PIC) simulation. When the ion-to-electron temperature ratio T i / T e is higher, the poloidal symmetry breaking in the filament propagation occurs. The poloidal symmetry breaking is thought to be induced by the unbalanced potential structure that arises from the effect of the gyro motion of plasma particles.

A Review on Dust Particle Image Analysis in Dusty Plasma

Plasma is gas of charged and neutral particles that exhibit collective behaviour. Studies of dusty plasma associated phenomena are known to have applications in many astrophysical environments, laboratory environments and in industrial plasma systems. Presence of dust particles in plasma invariably changes their behaviour and become dominant in terms of energy and momentum transport.The most prominent of these techniques are the Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV). Dust structures and motion of dust particles in plasma are studied in the laboratory by making optical measurements using the scattering of laser light.Taking a sequence of image is one of the most important methods of diagnosing dusty plasma. Understand the motion of the dust particles is also very important from the point of view of controlled nuclear fusion. Presence of dust in controlled nuclear fusion reactor is not desired and large amount of dust is expected to be produced in thermonuclear reactor, hence understanding the behaviour of dust particles in plasma and its efficient removal from the reactor will be useful from the point of view of controlled nuclear fusion. It holds the promise of potentially limitless and clean energy. This paper undertakes a comprehensive review of the various techniques discussed in these research papers and attempts to qualify them based on their approach, accuracy of results, ease of implementation and critical shortcomings.

Modeling of different scenarios of thin current sheet equilibria in the Earth’s magnetotail

The Earth’s magnetosphere is an open dynamic system permanently interacting with the solar wind, i.e., the plasma flow from the Sun. Some plasma processes in the magnetosphere are of spontaneous explosive character, while others develop rather slowly as compared to the characteristic times of plasma particle motion in it. The large-scale current sheet in the magnetotail can be in an almost equilibrium state both in quiet periods and during geomagnetic perturbations, and its variations can be considered quasistatic. Thus, under some conditions, the magnetotail current sheet can be described as an equilibrium plasma system. Its state depends on various parameters, in particular, on those determining the dynamics of charged particles. Knowing the main governing parameters, one can study the structure and properties of the current sheet equilibrium. This work is devoted to the self-consistent modeling of the equilibrium thin current sheet (TCS) of the Earth’s magnetotail, the thickness of which is comparable with the ion gyroradius. The main objective of this work is to examine how the TCS structure depends on the parameters characterizing the particle dynamics and magnetic field geometry. A numerical hybrid self-consistent TCS model in which the tension of magnetic field lines is counterbalanced by the inertia of ions moving through the sheet is constructed. The ion dynamics is considered in the quasi-adiabatic approximation, while the electron motion, in the conductive fluid approximation. Depending on the values of the adiabaticity parameter κ (which determines the character of plasma particle motion) and the dimensionless normal component of the magnetic field bz, the following two scenarios are considered: (A) the adiabaticity parameter is proportional to the particle energy and bz = const and (B) the particle energy is fixed and the adiabaticity parameter is proportional to bz. The structure of the current sheet and particle dynamics in it are studied as functions of the parameters κ and bz. It is shown that, in scenario A, the current sheet thickness decreases with increasing adiabaticity parameter due to a decrease in the ion gyroradius. Accordingly, the radius of curvature of magnetic field lines decreases, which leads to an increase in the contribution of electron drift currents near the neutral plane z = 0. Numerical simulations demonstrate that current equilibria can exist if the adiabaticity parameter lies in the range 0.05 ≤ κ ≤ 0.7. At κ ∼ 0.7, the contribution of electron drift currents to the total current density is much larger than the contribution of ions and the ion motion becomes chaotic. At larger values of the adiabaticity parameter, no equilibrium solutions were found in the framework of the given one-dimensional model. Therefore, the value κ = 0.7 corresponds to the upper applicability limit of the quasi-adiabatic model of the current sheet. In scenario B, an increase in the parameter κ leads to the appearance of a large number of quasi-trapped ions in the current sheet, due to which the current sheet thickens and the amplitude of the current density decreases. As a result, equilibrium solutions exist in a much narrower range of the adiabaticity parameter, 0.05≤ κ ≤ 0.25. Consequences of the existence of parametric boundaries of equilibrium solutions for the TCS under actual geomagnetic conditions are discussed.

Dust magneto-gravitational drift wave in g×B configuration

The dispersion relation of electrostatic waves in a magnetized complex plasma under gravity is presented. It is assumed that the waves propagate perpendicular to the external fields. The effects of weak electric field, neutral drag force, and ion drag force are also taken into account. The dispersion relation is numerically examined in an appropriate parameter space in which the gravity plays the dominant role in the dynamics of magnetized microparticles. The numerical results show that an unstable low frequency drift wave can be developed in the long wavelength limit. This unstable mode is transformed into an aperiodic stationary structure at a cut-off wavenumber. Furthermore, the influence of the external fields on the dispersion properties is analyzed. It is shown that the instability is essentially due to the E×B drift motion of plasma particles. However, in the absence of weak electric field, the g×B drift motion of microparticles can cause the instability in a wide range of wavenumbers. It is also found that by increasing the magnetic field strength, the wave frequency is first increased and then decreased. This behaviour is explained by the existence of an extremum point in the dust magneto-gravitational drift velocity.

On the mean profiles of radio pulsars - I. Theory of propagation effects

We study the influence of propagation effects on the mean profiles of radio pulsars using the method of wave propagation in inhomogeneous media described by Kravtsov & Orlov. This approach allows us first to take into consideration the transition from geometrical optics to vacuum propagation, the cyclotron absorption and the wave refraction simultaneously. In addition, the non-dipole magnetic field configuration, the drift motion of plasma particles and their realistic energy distribution are taken into account. It is confirmed that, for ordinary pulsars (period P ∼ 1 s, surface magnetic field B0 ∼ 1012 G) and typical plasma generation near the magnetic poles (multiplicity parameter λ = ne/nGJ ∼ 103), the polarization is formed inside the light cylinder at a distance resc ∼ 1000 R from the neutron star, the circular polarization being 5–20 per cent which is in agreement with observational data. A one-to-one correspondence between the signs of circular polarization and position angle (PA) derivative along the profile for both ordinary and extraordinary waves is predicted. Using numerical integration we now can model the mean profiles of radio pulsars. It is shown that the standard S-shape form of the PA swing can be realized for small enough multiplicity λ and large enough bulk Lorentz factor γ only. It is also shown that the value of the maximum derivative of PA, which is often used for determination of the angle between magnetic dipole and rotation axis, depends on the plasma parameters and could differ from the rotation vector model (RVM) prediction.

A detailed study of collisionless explosion of single- and two-ion-species spherical nanoplasmas

The collisionless adiabatic expansion into vacuum of spherical plasma targets (clusters) composed of cold single- or multispecies ions and hot electrons is studied kinetically by numerical solving of the nonrelativistic equations of motion of plasma particles in the self-consistent electrostatic field. The expansion dynamics for the whole range of electron temperatures from much less than to much higher than the cluster Coulomb energy is described for various initial plasma density profiles and cluster structures. The explosion of two ion species heterogeneous (layered) and homogeneously mixed targets is studied in detail for the wide range of light ion concentration and kinematic parameter.

Inverse problems for the Boltzmann-Vlasov kinetic equation: Representations for solutions and coefficients

Some exact representations are given for solutions and coefficients of the kinetic equation which describes motion of particles in plasma. The obtained solution possesses some functional arbitrariness.

Baryon loading and the Weibel instability in gamma-ray bursts

The dynamics of two counter-streaming electron-positron-ion unmagnetized plasma shells with zero net charge is analyzed in the context of magnetic field generation in GRB internal shocks due to the Weibel instability. The effects of large thermal motion of plasma particles, arbitrary mixture of plasma species and space charge effects are taken into account. We show that, although thermal effects slow down the instability, baryon loading leads to a non-negligible growth rate even for large temperatures and different shell velocities, thus guaranteeing the robustness and the occurrence of the Weibel instability for a wide range of scenarios.