Structures In Magnetized Plasma Research Articles

Interplay among turbulence, flow and impurities for sustaining magnetic island

As ubiquitous structures in magnetized fusion plasmas, magnetic islands (MIs) would short-circuit adjacent magnetic flux surfaces and result in a reduced pressure gradient and fluctuations inside the island; it is widely accepted that due to the stabilizing of drift wave instability, the turbulence intensity inside MIs is much lower for larger islands. Here, we provide the first observations that strong turbulence could be generated inside a large radiation MI, which is probably driven by the electron temperature dip due to strongly localized impurity radiation. Moreover, the flow velocity inside the MI is strongly correlated with the turbulence intensity, and the impurity concentration rate suddenly increases as the flow velocity reaches a threshold value, strongly suggesting that turbulence and flow inside the island play important roles in trapping heavy impurities and sustaining radiative MIs.

Direct observations of a complex coronal web driving highly structured slow solar wind

The solar wind consists of continuous streams of charged particles that escape into the heliosphere from the Sun, and is split into fast and slow components, with the fast wind emerging from the interiors of coronal holes. Near the ecliptic plane, the fast wind from low-latitude coronal holes is interspersed with a highly structured slow solar wind, the source regions and drivers of which are poorly understood. Here we report extreme-ultraviolet observations that reveal a spatially complex web of magnetized plasma structures that persistently interact and reconnect in the middle corona. Coronagraphic white-light images show concurrent emergence of slow wind streams over these coronal web structures. With advanced global magnetohydrodynamics coronal models, we demonstrate that the observed coronal web is a direct imprint of the magnetic separatrix web (S-web). By revealing a highly dynamic portion of the S-web, our observations open a window into important middle-coronal processes that appear to play a key role in driving the structured slow solar wind.

Kilotesla plasmoid formation by a trapped relativistic laser beam.

A strong quasistationary magnetic field is generated in hollow targets with curved internal surface under the action of a relativistically intense picosecond laser pulse. Experimental data evidence the formation of quasistationary strongly magnetized plasma structures decaying on a hundred picoseconds timescale, with the magnetic field strength of the kilotesla scale. Numerical simulations unravel the importance of transient processes during the magnetic field generation and suggest the existence of fast and slow regimes of plasmoid evolution depending on the interaction parameters. The proposed setup is suited for perspective highly magnetized plasma application and fundamental studies.

Superthermal electron’s effects on lump solitons structures in magnetized auroral plasma

Based on the considerations of the acknowledgements of the numerous space observations by satellites in the auroral plasma, astrophysics plasmas, spacecraft observations, various plasma models have been framed and revealed different interesting features, like electrostatic structures, solitary waves, double layers, supersolitons, etc. Soliton theory is a very efficient and competent way to describe nonlinear features. Using Viking satellite data in the auroral plasma, we have derived lump soliton solutions of the Kadomstev-Petviashvili (KP) equation by employing Hirota bilinear method. Due to its wide range of applications, the study of lump soliton is very attractive and important too. It has been shown that the lump solitons structures as well as in the one-dimensional form of lump soliton are varied with associated parameters in the auroral magnetized plasma. During the analysis of the features of the lump solitons, it is found that the system parameters play a pivotal role on the lump solitons structures.

The Algebra of Cosmic Intelligence: Inhumanism and Cosmology in the Reflexive Neocybernetics of Vladimir Lefebvre

ABSTRACT This article reconstructs the theory of the Soviet-American psychologist Vladimir Lefebvre as part of the neocybernetic movement. In particular, I propose to explore such elements of his research of the 1970s—1990s as systemic vision; reflexive analysis; a search for holistic configuration and Janus cosmology; and the realization of neocybernetics. An interest in the reflexive structures of cognition and action led Lefebvre to an understanding of the limited nature of the world’s scientific picture. The conflicting objects he studied proved too complex for behavioral modeling and forecasting. Lefebvre therefore expanded the boundaries of the application of his formal theory of intelligence, relying on functionalist positions, which led him to the science-fiction narrative of “The Big Correction.” I contend that Lefebvre’s works not only propose an original Soviet version of the neocybernetics the 1970s but develop their own model of inhumanism long before it appeared on the scene of modern philosophy. Lefebvre’s formal theory, reinforced by thermodynamics and elements of Russian cosmism, builds cognitive behavior into the teleology of the Big Correction, which involves the idea of overcoming the heat death of the universe. The activity of cosmic intelligence, which Lefebvre equates with magnetic-plasma structures in the finished areas of the universe, is aimed at cooperation and prolonging the existence of life and the intellect.

Painlevé analysis, auto-Bäcklund transformation and analytic solutions for modified KdV equation with variable coefficients describing dust acoustic solitary structures in magnetized dusty plasmas

In this paper, variable coefficients mKdV equation is examined by using Painlevé analysis and auto-Bäcklund transformation method. The proposed equation is an important equation in magnetized dusty plasmas. The Painlevé analysis is used to determine the integrability whereas an auto-Bäcklund transformation technique is being explored to derive unique family of analytical solutions for variable coefficients mKdV equation. New kink–antikink and periodic-kink- type soliton solutions have been determined successfully for the considered equation. This paper shows that auto-Bäcklund transformation method is effective, direct and easy to use, and used to determine the analytic soliton solutions of various nonlinear evolution equations in the field of science and engineering. The results are plotted graphically to signify the potency and applicability of this proposed scheme for solving the above considered equation. The obtained results are in the form of soliton-like solutions, solitary wave solutions, exponential and trigonometric function solutions. Therefore, these solutions help us to understand the potential and physical behaviors of the proposed equation.

Torsional waves with force-free magnetic fields in solar plasma structures

ABSTRACT The aim here is to model torsional waves in homogeneous and expanding twisted flux tubes of solar coronal magnetic plasma structures. For the sake of simplicity, a force-free condition applicable to solar magnetic structures is presented to determine the existing three-dimensional equilibrium magnetic fields. The determined magnetic field is implemented to study the effects of the magnetic twist parameter on the eigenvalues and eigenfunctions of torsional waves. Solenoidal and force-free conditions are applied to find the three-dimensional components of the magnetic field with respect to the numerical flux function. The obtained differential equation is linear where the technique of the separation of variables is implemented in order to solve it. The equilibrium magnetic field components and appropriate vector potential are extracted. Using the provided components in the magnetohydrodynamic theory, a differential equation that governs the frequency dependence of the torsional wave is obtained, whereby the differential transform method is solved. Both eigenvalues and eigenfunctions of torsional waves are calculated numerically. The obtained values for the frequency of the fundamental mode and its first harmonic, together with appropriate functions, exhibit a fine consistency with observations, with regards to the ratio of ω2/ω1, which is estimated to be around 2. At a fixed distance from the tube axis, the ratio increases with the increase of the twist parameter. The higher the applied twist parameter, the more variations of the ω2/ω1 ratio are observed. We cannot find significant variations of the eigenfunctions of torsional waves due to the twist parameter. The consistency between analytical results and observations proves adequate for implementing a force-free equilibrium magnetic field subject to conditions in solar plasma structures regarding torsional wave propagation.

Effects of plasma turbulence on the nonlinear evolution of magnetic island in tokamak

Magnetic islands (MIs), resulting from a magnetic field reconnection, are ubiquitous structures in magnetized plasmas. In tokamak plasmas, recent researches suggested that the interaction between an MI and ambient turbulence can be important for the nonlinear MI evolution, but a lack of detailed experimental observations and analyses has prevented further understanding. Here, we provide comprehensive observations such as turbulence spreading into an MI and turbulence enhancement at the reconnection site, elucidating intricate effects of plasma turbulence on the nonlinear MI evolution.

Flux Ropes Are Born in Pairs: An Outcome of Interlinked, Reconnecting Flux Tubes

AbstractFlux transfer events are transient magnetized plasma structures that are self‐balancing, rope‐like phenomena that can appear at the Earth's magnetopause when the interplanetary magnetic field is southward. The formation of this type of flux rope has been unclear. Using measurements of particles and magnetic fields on the MMS spacecraft, we find that rope‐like structures containing magnetospheric energetic electrons have exactly the same occurrence rate as those without magnetospheric electrons, independent of solar wind properties and location of observation. This equality is consistent with a pair of flux bundles being generated at the same time but displaced from each other as an outcome of their collision and resultant entanglement and reconnection. This entanglement reconnection produces one flux rope with two ends connected to the magnetosphere and the other connected on both ends to the shocked solar wind. Away from the subsolar entanglement zone, reconnection transports magnetic flux from the “closed” magnetosphere to the “open” tail lobes, as predicted by Dungey (1961, https://doi.org/10.1103/PhysRevLett.6.47).

The influence of Landau quantization on the propagation of solitary structures in collisional plasmas

In this work, we study damped ion acoustic solitary wave structures in magnetized dense plasmas. The collisional effects of ions with electrons and neutrals are considered. The trapping effects of electrons and Landau quantization are included in the plasma model under consideration. We assume that magnetic field is quantized such that the condition is satisfied. We have derived the damped Korteweg–de Vries (dKdV) equation by using small amplitude reductive perturbation technique. The time-dependent analytical and numerical solutions of the dKdV equation are presented. For numerical solutions we apply a two level finite difference scheme with the help of the Runge Kutta method. The effects of variations of different plasma parameters on the propagation characteristics of damped solitary structures in the presence of collisions are discussed.

Experimental observation and numerical investigation of filamentary structures in magnetized plasmas

Filamentary structures in low-pressure, low-temperature plasmas are produced when strong magnetic fields are applied parallel to the electric field defined by parallel electrodes. Filamentary structures are regions within the plasma that have distinct properties such as optical brightness and extend along the magnetic field lines. In our experiments, an argon, radio frequency discharge is exposed to a strong background magnetic field in the magnetized dusty plasma experiment at Auburn University. Different forms of filamentary structures emerge in the plasma such as columns, target, or spiral-like structures. To investigate the origin and the characteristics of these patterns, we have developed a three-dimensional fluid model that can reproduce the experimental observations which enables us to investigate the underlying mechanisms of the filamentation process.

Three-dimensional Nonlinear Structures in Magnetized Complex Plasmas

A three-dimensional multi-component magneto-plasma system consisting of hybrid nonextensive-nonthermal-distributed electrons, positive ions, and immobile negatively charged dust grains is considered to examine the modulational instability (MI) of dust ion-acoustic waves (DIAWs). The reductive perturbation method, which is valid for small but finite amplitude DIAWs, is employed to derive the (3 + 1)-dimensional nonlinear Schrodinger equation (NLSE). The NLSE leads to the MI of DIAWs as well as the formation of dust ion-acoustic rogue waves (DIARWs), which are formed due to the effects of nonlinearity in the propagation of DIAWs. It is found that the basic features (viz. amplitude and width) of the DIAWs and DIARWs (which is formed in the unstable region) are significantly modified by the various plasma parameters such as non-extensive (non-thermal) parameter q(α), number densities of plasma species, threshold modulational obliqueness ($${{\theta }_{c}}$$), etc. The application of the results in space and laboratory magneto-plasma system is briefly discussed.

Magnetized plasma implosion in a snail target driven by a moderate-intensity laser pulse

Optical generation of compact magnetized plasma structures is studied in the moderate intensity domain. A sub-ns laser beam irradiated snail-shaped targets with the intensity of about 1016 W/cm2. With a neat optical diagnostics, a sub-megagauss magnetized plasmoid is traced inside the target. On the observed hydrodynamic time scale, the hot plasma formation achieves a theta-pinch-like density and magnetic field distribution, which implodes into the target interior. This simple and elegant plasma magnetization scheme in the moderate-intensity domain is of particular interest for fundamental astrophysical-related studies and for development of future technologies.

Higher harmonic waveforms are revealed in nonlinear structures of magnetized plasma

Newly found characteristics of nonlinear streamer structures in magnetized plasma include self-coupled higher harmonics, plus a relation between the streamer’s envelope and the mediator’s waveform.

Coherent transport structures in magnetized plasmas. II. Numerical results

In a pair of linked articles (called Papers I and II, respectively), we apply the concept of Lagrangian Coherent Structures borrowed from the study of Dynamical Systems to chaotic magnetic field configurations in order to separate regions where field lines have different kinds of behavior. In the present article, Paper II, by means of a numerical procedure, we investigate the Lagrangian Coherent Structures in the case of a two-dimensional magnetic configuration with two island chains that are generated by magnetic reconnection and evolve nonlinearly in time. The comparison with previous results, obtained by assuming a fixed magnetic field configuration, allows us to explore the dependence of transport barriers on the particle velocity.

Whispering Gallery Effect in Relativistic Optics

A relativistic laser pulse, confined in a cylindrical-like target, under specific conditions may perform multiple scattering along the internal target surface. This results in the confinement of the laser light, leading to a very efficient interaction. The demonstrated propagation of the laser pulse along the curved surface is just yet another example of the “whispering gallery” effect, although nonideal due to laser–plasma coupling. In the relativistic domain its important feature is a gradual intensity decrease, leading to changes in the interaction conditions. The process may pronounce itself in plenty of physical phenomena, including very efficient electron acceleration and generation of relativistic magnetized plasma structures.

Physics of erupting solar flux ropes: Coronal mass ejections (CMEs)—Recent advances in theory and observation

Solar eruptions, observed as flares and coronal mass ejections (CMEs), are the most energetic visible plasma phenomena in the solar system. CMEs are the central component of solar eruptions and are detected as coherent magnetized plasma structures expanding in the solar wind (SW). If they reach the Earth, their magnetic fields can drive strong disturbances in the ionosphere, causing deleterious effects on terrestrial technological systems. The scientific and practical importance of CMEs has led to numerous satellite missions observing the Sun and SW. This has culminated in the ability to continuously observe CMEs expanding from the Sun to 1 AU, where the magnetic fields and plasma parameters of the evolved structures (“ejecta”) can be measured in situ. Until recently, the physical mechanisms responsible for eruptions were major unanswered questions in solar and by extension stellar physics. New observations of CME dynamics and associated eruptive phenomena are now providing more stringent constraints on models, and quantitative theory-data comparisons are helping to establish the correct mechanism of solar eruptions, particularly the driving force of CMEs and the evolution of their magnetic fields in three dimensions. Recent work has demonstrated that theoretical results can simultaneously replicate the observed CME position-time data, temporal profiles of associated solar flare soft X-ray emissions, and the magnetic field and plasma parameters of CME ejecta measured at 1 AU. Thus, a new theoretical framework with testable predictions is emerging to model eruptions and the coupling of CME ejecta to geomagnetic disturbances. The key physics in CME dynamics is the Lorentz hoop force acting on toroidal “flux ropes,” scalable from tokamaks and similar laboratory plasma structures. The present paper reviews the latest advances in observational and theoretical understanding of CMEs with the emphasis on quantitative comparisons of theory and observation.

Magnetized plasma structures in laser-irradiated curved targets

This work presents an extensive theoretical study of magnetic field generation effect in hollow targets with curved internal surface, known as “snail” or “escargot” targets []. They were recently proposed as a robust setup for generating intense spontaneous quasi-stationary magnetic fields frozen in laser-produced plasmas. The results of such studies are indispensable for planing experimental investigations and for possible applications of the curved targets, including, but not limited to, laboratory astrophysics, fast ignition, and particle acceleration.

Pulsating jet-like structures in magnetized plasma

The formation of pulsating jet-like structures has been studied in the scope of the nonhydrostatic model of a magnetized plasma with horizontally nonuniform density. We discuss two mechanisms which are capable of stopping the gravitational spreading appearing to grace the Rayleigh-Taylor instability and to lead to the formation of stationary or oscillating localized structures. One of them is caused by the Coriolis effect in the rotating frames, and another is connected with the Lorentz effect for magnetized fluids. Magnetized jets/drops with a positive buoyancy must oscillate in transversal size and can manifest themselves as “radio pulsars.” The estimates of their frequencies are made for conditions typical for the neutron star's ocean.

Magnetosonic Shocks in Ultra-Relativistic Dissipative Degenerate Plasmas

Magnetosonic shock structures in dissipative magnetized degenerate electron ion plasma are studied. The two fluid quantum magnetohydrodynamic equations for non-degenerate ions and ultra-relativistic degenerate electron fluids with the Maxwell equations are presented. Using the reductive perturbation technique the Korteweg de Vries Burgers (KdVB) equation is derived and its solution is presented with the tanh method. Astrophysical plasma parameters are used to study the effects of variation of plasma density, magnetic field intensity and kinematic viscosity on the propagation characteristics of nonlinear shock structures in such plasma systems.