Two-dimensional Magnetized Plasma Research Articles

On acoustic solitary waves in a multispecies degenerate relativistic magnetized plasma using physics informed neural networks

In this paper, we investigate the nonlinear electrostatic wave propagation in a two-dimensional magnetized plasma. The plasma consists of electron and positron components with relativistic degeneracy and stationary ions for neutralizing its background. Using the basic equations for this type of plasma in combination with the reductive perturbation method, we derived the Zakharov–Kuznetsov equation using the Lorentz transformation stretching method (LT). For the first time, we compared the results of the Galilean transformation stretching method (GT) and the LT method to investigate the effect of plasma parameters, such as the relativistic degeneracy parameter of electron particles (re0), the density ratio of ion to electrons (δ), and the normalized electron cyclotron (Ωe), on the amplitude and width of the wave solutions. The plasma parameters used in this research are representative of compact astrophysical objects. Numerical results showed that the amplitude of wave solutions obtained by the LT method is smaller than the GT method, but the width is greater. We provide a physical explanation for these differences. Furthermore, we present a physics-informed neural network (PINN) approach to directly recover the intrinsic nonlinear dynamics from spatiotemporal data. The PINN model uses a deep neural network constrained by the governing equations to learn the optimal parameters, with the aim of enhancing the predictive capabilities of the system. The results of this study provide valuable insight into the propagation of nonlinear waves in white dwarfs, where relativistic effects are significant. These findings could substantially advance the development of emerging machine learning applications in astrophysics.

Tunable band structure in two-dimensional magnetized plasma photonic crystal for sensing applications in terahertz frequencies

Tunable band structure in two-dimensional magnetized plasma photonic crystal for sensing applications in terahertz frequencies

Designing externally controllable optical filters with two-dimensional magnetized plasma photonic crystals

Designing externally controllable optical filters with two-dimensional magnetized plasma photonic crystals

Bandgap structure and density of states of two-dimensional magnetized plasma photonic crystals

In this paper, we study dispersion properties in a two-dimensional magnetized plasma photonic crystal, based on the modified plane wave expansion method. Transverse electric polarization is considered. The influence of different factors such as external magnetic field, lattice constant, dielectric constants of background and central rod, and electron density of plasma in photonic bandgap structure and photonic bandgap map is studied. The photonic density of states is also demonstrated. Results show that a large magnetic field produces more band gaps in higher frequencies. The lattice constant is an important factor in controlling the bandgap structure and it can compensate low magnetic field effect. Using a larger dielectric constant in the background compared to the central dielectric rod leads to more and sharper band gaps in higher frequencies. Electron density of plasma plays an important role in tuning bandgap structure. There would be three or four band areas in the band structure and the band frequencies are larger than the cutoff frequency of plasma.

Geometric electrostatic particle-in-cell algorithm on unstructured meshes

We present a geometric particle-in-cell (PIC) algorithm on unstructured meshes for studying electrostatic perturbations with frequency lower than electron gyrofrequency in magnetized plasmas. In this method, ions are treated as fully kinetic particles and electrons are described by the adiabatic response. The PIC method is derived from a discrete variational principle on unstructured meshes. To preserve the geometric structure of the system, the discrete variational principle requires that the electric field is interpolated using Whitney 1-forms, the charge is deposited using Whitney 0-forms and the electric field is computed by discrete exterior calculus. The algorithm has been applied to study the ion Bernstein wave (IBW) in two-dimensional magnetized plasmas. The simulated dispersion relations of the IBW in a rectangular region agree well with theoretical results. In a two-dimensional circular region with fixed boundary condition, the spectrum and eigenmode structures of the IBW are obtained from simulations. We compare the energy conservation property of the geometric PIC algorithm derived from the discrete variational principle with that of previous PIC methods on unstructured meshes. The comparison shows that the new PIC algorithm significantly improves the energy conservation property.

External-field driven motion of charged grains in magnetized plasma

Long-time evolution of charged grains in a two-dimensional magnetized plasma under a spatially harmonic external force is investigated using molecular dynamics simulation. It is found that the grains can converge into a single quasi-steady crystal disc, and their trajectories trace out a complex but regular flowery pattern that gradually becomes simpler in time until a quasi-steady rotating pattern is reached.

Enstrophy non-conservation and the forward cascade of energy in two-dimensional electrostatic magnetized plasma turbulence

A fluid system is derived to describe electrostatic magnetized plasma turbulence at scales somewhat larger than the Larmor radius of a given species. It is related to the Hasegawa–Mima equation, but does not conserve enstrophy, and, as a result, exhibits a forward cascade of energy, to small scales. The inertial-range energy spectrum is argued to be shallower than a $-11/3$ power law, as compared to the $-5$ law of the Hasegawa–Mima enstrophy cascade. This property, confirmed here by direct numerical simulations of the fluid system, may help explain the fluctuation spectrum observed in gyrokinetic simulations of streamer-dominated electron-temperature-gradient driven turbulence (Plunk et al., Phys. Rev. Lett., vol. 122, 2019, 035002), and also possibly some cases of ion-temperature-gradient driven turbulence where zonal flows are suppressed (Plunk et al., Phys. Rev. Lett., vol. 118, 2017, 105002).

Direct electron acceleration with a linearly polarized laser beam in a two-dimensional magnetized plasma channel

AbstractWe examine the electron acceleration induced by an ultra-relativistic intensity laser–plasma interaction in a two-dimensional plasma channel in the presence of a self-generated transverse magnetic field. We find that the electron dynamics is strongly affected by the laser pulse polarization angle, plasma density, and magnetic field strength. We investigate in detail, the dependencies of the electron acceleration in terms of different parameters and find excellent agreement with non-magnetized plasma in the absence of the magnetic field. The numerical results show that the self-generated magnetic field plays a constructive role in the electron acceleration process. It is shown that electron acceleration is more affected by self-generated magnetic field for the laser radiations with large polarization angles. The numerical results show the maximum enhancement for electron acceleration for a laser radiation with polarization angle θ = π/2.

Parallel magneticcontrolled THz modulator based on two-dimensional magnetized plasma photonic crystal

THz waves are very good candidates for high-capacity wireless links since they offer a much higher bandwidth than RF frequencies. Photonic crystal (PC) offers a new opportunity for integrated THz wave devices. It permits the integrated devices to be miniaturized to a scale comparable to the wavelength of the electromagnetic wave. Considering their governing properties such as photonic band gap (PBG) and photon localization effect to control electromagnetic wave propagations, PC-based THz modulator has attracted much attention. Tunability strategies include mechanical control, electrical control, magneto static control, temperature control and optical pumping. However, the development of high-speed THz wireless communication system is limited by the low modulation depth and rate of previously reported modulators. In this paper, we propose a novel magnetic-controlled THz modulator based on a magnetized plasma PC consisting of line defects and a point defect. InSb, a semiconductor with high electron mobility, is introduced into the point defect. According to the magneto-optical effect, the refractive index of InSb changes rapidly under the control of the applied magnetic field (MF) intensity. Then the mode frequency in the point defect changes dynamically. The structure is based on a two-dimensional PC constructed by triangular lattice of Si rods in air. Based on the magneto-optic effect, the magnetized plasma defect mode in the THz regime can be decomposed into the left- and right-handed circularly polarized light when the applied magnetic field is parallel to the direction of the THz wave. And the difference in effective refractive index between the left- and right-handed circularly polarized light increases with the applied uniform magnetic field increasing. Therefore the on/off modulation of left- and right-hand circularly polarized light can be realized. The steady-state field intensity distribution and the time domain steady state response of TE wave propagating parallelly to the external magnetic field are simulated by the finite-difference-time-domain and finite element method. The simulation results show that PC-based mode transfer modulator has the potential application to THz wireless broadband communication system with a good performance of high contrast ratio (25.4 dB), low insertion loss (0.3 dB) and high modulation rate (～4 GHz). It is convenient to load the modulation signals in an easy MF application way. The device designed is leading the way to extend the application of THz wireless communication filed with advantages of small size, low insertion loss, and high extinction ratio.

Diffusion in Two-dimensional Magnetized Dusty Plasmas

A molecular dynamical simulation method is used to investigate the diffusion of the two-dimensional magnetized dusty plasmas. The effects of charge and mass of the particles, as well as the external magnetic field are discussed in detail. It is shown that, relative to the mass of particulate, the charge and magnetic field have a more considerable effect on the diffusion process, particularly on the resulting structure of the system. The dependence of diffusion coefficient on the temperature is shown to be linearly changed over a wide range of temperature.

On linear transformation of waves in a two-dimensional inhomogeneous magnetized plasma with collisional absorption

UDC 537.876 We consider the linear coupling of waves in the electron-cyclotron frequency range in a nonone-dimensional inhomogeneous magnetized plasma in the vicinity of the plasma cutoff surface with allowance for their collisional dissipation. Model wave equations describing the normal wave interaction in the considered case are formulated and solved analytically. Effects of the absorption anisotropy typical of magnetized plasma on the linear mode coupling in two-dimensional inhomogeneous geometry are analyzed.

Photonic band structures of two-dimensional magnetized plasma photonic crystals

By using modified plane wave method, photonic band structures of the transverse electric polarization for two types of two-dimensional magnetized plasma photonic crystals are obtained, and influences of the external magnetic field, plasma density, and dielectric materials on the dispersion curves are studied, respectively. Results show that two areas of flat bands appear in the dispersion curves due to the role of external magnetic field, and the higher frequencies of the up and down flat bands are corresponding to the right-circled and left-circled cutoff frequencies, respectively. Adjusting external magnetic field and plasma density can not only control positions of the flat bands, but also can control the location and width of the local gap; increasing relative dielectric constant of the dielectric materials makes omni-direction gaps appear.

Magnetic reconnection from a multiscale instability cascade

Magnetic reconnection, the process whereby magnetic field lines break and then reconnect to form a different topology, underlies critical dynamics of magnetically confined plasmas in both nature and the laboratory. Magnetic reconnection involves localized diffusion of the magnetic field across plasma, yet observed reconnection rates are typically much higher than can be accounted for using classical electrical resistivity. It is generally proposed that the field diffusion underlying fast reconnection results instead from some combination of non-magnetohydrodynamic processes that become important on the 'microscopic' scale of the ion Larmor radius or the ion skin depth. A recent laboratory experiment demonstrated a transition from slow to fast magnetic reconnection when a current channel narrowed to a microscopic scale, but did not address how a macroscopic magnetohydrodynamic system accesses the microscale. Recent theoretical models and numerical simulations suggest that a macroscopic, two-dimensional magnetohydrodynamic current sheet might do this through a sequence of repetitive tearing and thinning into two-dimensional magnetized plasma structures having successively finer scales. Here we report observations demonstrating a cascade of instabilities from a distinct, macroscopic-scale magnetohydrodynamic instability to a distinct, microscopic-scale (ion skin depth) instability associated with fast magnetic reconnection. These observations resolve the full three-dimensional dynamics and give insight into the frequently impulsive nature of reconnection in space and laboratory plasmas.

Self-organization and symmetry-breaking in two-dimensional plasma turbulence

The spontaneous self-organization of two-dimensional magnetized plasma is investigated within the framework of magnetohydrodynamics with a particular emphasis on the symmetry-breaking induced by the shape of the confining boundaries. This symmetry-breaking is quantified by the angular momentum, which is shown to be generated rapidly and spontaneously from initial conditions free from angular momentum as soon as the geometry lacks axisymmetry. This effect is illustrated by considering circular, square, and elliptical boundaries. It is shown that the generation of angular momentum in nonaxisymmetric geometries can be enhanced by increasing the magnetic pressure. The effect becomes stronger at higher Reynolds numbers. The generation of magnetic angular momentum (or angular field), previously observed at low Reynolds numbers, becomes weaker at larger Reynolds numbers.

Turbulence and transport in two-dimensional magnetized electron plasmas

Electron plasmas confined by an external magnetic field exhibit variations in a two-dimensional plane orthogonal to the confining magnetic field. A nonlinear fluid simulation code to investigate the properties of 2D electron plasma wave turbulence in a nonuniform magnetoplasma has been developed. It is found that the presence of the density gradient convection by mean electric fields considerably influence the characteristic nonlinear interaction processes, such as the energy cascades and the cross-field electron transport. The initial random turbulent state evolves towards an intermittent state where forward cascade of vorticity coexists with an inverse cascade of electric potential fluctuations. The latter lead to the formation of large scale entities in 2D electron plasmas and can be alternatively understood by seeking exact nonlinear coherent vortex solutions in the form of a dipolarlike configuration. The energy cascades are governed typically by the Kolmogorov-type k−5∕3 spectrum. In agreement with the experimental observations, we find that the electron transport is improved significantly by the application of an externally imposed electric field.

Kinetic equation for charged particles in axisymmetric two-dimensional magnetized plasmas

Kinetic equation for charged particles in axisymmetric two-dimensional magnetized plasmas

City of Light: The Story of Fiber Optics. Jeff Hecht

Previous articleNext article No AccessBook ReviewsCity of Light: The Story of Fiber Optics. Jeff Hecht Mark Henry ClarkMark Henry Clark Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Isis Volume 92, Number 2Jun., 2001 Publication of the History of Science Society Article DOIhttps://doi.org/10.1086/385261 Views: 5Total views on this site Citations: 1Citations are reported from Crossref Copyright 2001 The History of Science Society, Inc.PDF download Crossref reports the following articles citing this article:Kazem Jamshidi-Ghaleh, Fahimeh Karami-Garehgeshlagi, Farzaneh Bayat Designing externally controllable optical filters with two-dimensional magnetized plasma photonic crystals, The European Physical Journal D 76, no.88 (Aug 2022).https://doi.org/10.1140/epjd/s10053-022-00466-8

Zonal flow generation by parametric instability in magnetized plasmas and geostrophic fluids

Two-dimensional magnetized plasmas and geostrophic fluids exhibit a common nonlinearity due to the advection of vorticity. It is shown here that due to this nonlinearity, the propagation of small scale wave packets is accompanied by instability of a low frequency, long wavelength component. This instability is the coherent hydrodynamic generalization of the resonant type mean flow instability identified recently [P. H. Diamond, M. N. Rosenbluth, F. L. Hinton, M. Malkov, J. Fleischer, and A. Smolyakov, 17th IAEA Fusion Energy Conference, IAEA-CN-69/TH3/1, Yokohama, 1998 (to be published, International Atomic Energy Agency, Vienna)]. The mechanism discussed here, along with the resonant type, constitutes the “hydrodynamic” and “kinetic” regimes of the same process, similar to the case of plasma-beam instabilities. It is suggested that this generic mechanism is responsible for the generation of mean flow in atmospheres of rotating planets and magnetized plasmas.

Collisionless Diffusion of Particles and Current Across a Magnetic Field in Beam/Plasma Interaction

A drift-kinetic Eulerian Vlasov code with fluid equations for the ions is used to study the collisionless diffusion of particles and current across a magnetic field for the case of an electron beam injected near the edge of a two-dimensional magnetized plasma slab. The case of a magnetic field tilted with respect to the beam direction at an angle of θ = 10 deg is considered. Test particles diagnostic techniques are used to study the evolution of the phase space at different locations across the plasma slab. We analyze the anomalous diffusion process triggered by the beam-plasma instability and induced in space across the magnetic field by the Kelvin-Helmholtz instability and the velocity space diffusion induced along the magnetic field due to the kinetic effects of the beam-plasma instability. In the present slab geometry it is found that the collisionless diffusion coefficients D y and D v ∥, describing respectively the anomalous diffusion in physical space and in velocity space, are related by the relation D y = D v ∥ tan 2 θ/ω ce 2 . This relation, which links the electron dynamics in the x-y real space and in the y-v∥ phase space, is verified accurately using the test particles diagnostic techniques. The Vlasov code associated with test particles techniques provides a powerful tool to study particle diffusion in space and in phase space, especially in the low-density regions of the distribution function.

Study of the diffusion across a magnetic field in a beam–plasma interaction using a drift-kinetic Vlasov code

A drift-kinetic Eulerian Vlasov code, with fluid equations for the ions, is developed to study the problem of the injection of an electron beam into a two-dimensional magnetized plasma, often referred to as direct current (dc) helicity injection. The diffusion of electrons across a magnetic field in the presence of a beam–plasma instability is studied. The case of a magnetic field tilted with respect to the beam direction is considered. The competition between the velocity shear Kelvin–Helmholtz (KH) and the beam–plasma (BP) instabilities is investigated in order to analyze the plasma heating and current drive mechanism induced by the beam injection. The KH instability generates low-frequency plasma convection motion associated with cE×B/B2 drift. In particular, the diffusion coefficients Dy and Dv ∥ describing, respectively, the anomalous diffusion process induced in space across the magnetic field by the KH instability, and the velocity diffusion process due to the kinetic effects induced in velocity space along the magnetic field by the BP instability, are computed using test-particle diagnostics. In the present Cartesian model, it is found that Dy = Dv∥ tan2 θ/ωce2 where θ is the angle between the magnetic field and the x axis. This relation which links the electron dynamics in the x-y real space and in the x-v∥ phase space is verified by the numerical code. The Vlasov code provides a powerful tool to study particle diffusion in space and in phase space, especially in the low-density regions of the distribution function.