Intense Electromagnetic Wave Research Articles

Acceleration of Electrons and Ions by an “Almost” Astrophysical Shock in the Heliosphere

Collisionless shock waves, ubiquitous in the Universe, are crucial for particle acceleration in various astrophysical systems. Currently, the heliosphere is the only natural environment available for their in situ study. In this work, we showcase the collective acceleration of electrons and ions by one of the fastest in situ shocks ever recorded, observed by the pioneering Parker Solar Probe at only 34.5 million km from the Sun. Our analysis of this unprecedented, near-parallel shock shows electron acceleration up to 6 MeV amidst intense multiscale electromagnetic wave emissions. We also present evidence of a variable shock structure capable of injecting and accelerating ions from the solar wind to high energies through a self-consistent process. The exceptional capability of the probe’s instruments to measure electromagnetic fields in a shock traveling at 1% the speed of light has enabled us, for the first time, to confirm that the structure of a strong heliospheric shock aligns with theoretical models of strong shocks observed in astrophysical environments. This alignment offers viable avenues for understanding astrophysical shock processes and the self-consistent acceleration of charged particles.

Scattering Cross Sections of Magnetized Particles within Intense Electromagnetic Waves: Application to Fast Radio Bursts

Abstract Recently, Beloborodov suggested that there exists a resonance phenomenon between an extremely intense electromagnetic wave and internal magnetized particles. The particles exchange energy with the wave at frequent resonance events and then reach the radiation reaction limit immediately. This process greatly enhances the scattering cross section of the particles. Note that these results only involve an extraordinary (X) mode wave. In this paper, we focus on an intense ordinary (O) mode wave propagating through magnetized particles and compare it with the case of the X-mode wave. Our result shows that the scattering cross section of the particles in the O-mode wave is significantly smaller than that in the X-mode wave. This has important implications for the transparency of a fast radio burst (FRB) inside the magnetosphere of a magnetar. We argue that there is a strong scattering region in the stellar magnetosphere, within which an O-mode wave is more transparent than an X-mode wave for an FRB.

A New Approach to Nuclear Fusion Based on Muon Catalysis by Means of High-Energy Ball Lightning and an Accelerative Mechanism

A new method of realizing nuclear fusion reactions based on muon catalysis and the accelerative mechanism is proposed. High-energy ball lightning is periodically generated in a reactor chamber filled with deuterium gas and directed into a container containing liquid tritium. The entry of ball lightning into the tritium is accompanied by the generation of muons and mesomolecules due to a cascade process. Following the ball lightning, a high-energy plasma jet moves under the influence of traveling transverse electromagnetic waves. Deuterium ions and electrons of the jet, accelerated by intense transverse electromagnetic waves, interact with the tritium. Nuclear fusion reactions occur with the participation of muonic molecules at very low temperature. The developed method resolves all physical and technical problems that are inherent in existing traditional methods.

Possible Global Generation Region of Nonlinear Whistler‐Mode Chorus Emission Waves at Mercury

AbstractChorus waves are a kind of intense electromagnetic emission wave in magnetized planets and can play important roles in the kinetic electron dynamics in planetary magnetospheres. Rapid changes of the ring electron current belt in Mercury’s magnetosphere and the contribution of chorus waves have remained long‐standing scientific issues from the first Mercury flyby observations by Mariner 10 in 1970s because of the small size of the magnetosphere. Based on theoretical analyses and simulations successfully reconstructing Earth’s chorus wave properties, we report on possible generation regions of chorus waves in Mercury’s magnetosphere. The theoretical analysis for low‐temperature‐anisotropy electrons shows a clear asymmetric day–night spatial distribution of the possible chorus generation region because of the difference in the nonlinear convective wave growth along the magnetic field lines. Simulation results show a rapid enhancement of the ring electron current belt by resonant interactions with repetitive chorus waves. Our study suggests that energetic electrons in Mercury’s magnetosphere can be enhanced locally by nonlinear chorus wave–particle interactions.

Radio Pulsars Resonantly Accelerating Electrons

Based on the recently demonstrated resonant wave–wave process, it is shown that electrons can be accelerated to ultra-relativistic energies in the magnetospheres of radio pulsars. The energization occurs via the resonant interaction of the electron wave (described by the Klein–Gordon (KG) equation) moving in unison with an intense electromagnetic (EM) wave; the KG wave/particle continuously draws energy from EM. In a brief recapitulation of the general theory, the high-energy (resonantly enhanced) electron states are investigated by solving the KG equation, minimally coupled to the EM field. The restricted class of solutions that propagate in phase with EM radiation (functions only of ζ=ωt−kz) are explored to serve as a possible basis for the proposed electron energization in the radio pulsars. We show that the wave–wave resonant energization mechanism could be operative in a broad class of radio pulsars with periods ranging from milliseconds to normal values (∼1 s); this could drive the magnetospheric electrons to acquire energies from 100 s of TeVs (millisecond pulsars) to 10 ZeVs (normal pulsars).

THE ROLE OF HIGHER MOMENTS ON THE DISTRIBUTION OF PARTICLES IN THE SPACE OF IMPULSES AT CYCLOTRON RESONANCES

The results of the analysis of the dynamics of charged particles under conditions of cyclotron resonances in the field of an intense electromagnetic wave are presented. Particular attention is paid to regimes with dynamic chaos. It is shown that there are two qualitatively different regimes. The appearance of the first one is due to the overlap of nonlinear cyclotron resonances. The second mode is related to intermittency. The moments and spectra of each of these regimes are determined. It is shown that with an increase in the intensity of an external electromagnetic wave, the first regime appears at the beginning and only then the second regime appears. A characteristic feature of the second regime is intermittency. Steps appear on the time dynamics of pulses in the second mode. It is shown that the spectra in the second mode are narrower than in the first mode. A characteristic feature of the second regime (the regime with intermittency) is the fact that the higher moments turn out to be larger than the lower moments. In the first regime, the highest moments decrease rapidly. To find the particle momentum distribution function, the generalized Fokker-Planck equation was used. Solutions of this equation are written out for some important cases.

Comment on: “Interacting quantum and classical waves: Resonant and non-resonant energy transfer to electrons immersed in an intense electromagnetic wave” [Phys. Plasmas 29, 022107 (2022)

Comment on: “Interacting quantum and classical waves: Resonant and non-resonant energy transfer to electrons immersed in an intense electromagnetic wave” [Phys. Plasmas <b>29</b>, 022107 (2022)

Response to comment on “Interacting quantum and classical waves: Resonant and non-resonant energy transfer to electrons immersed in an intense electromagnetic wave” [Phys. Plasmas 30, 084701 (2023)

This is a note in response to Dr. Machi's comment on our recent paper [S. M. Mahajan and F. A. Asenjo, Phys. Plasmas 29, 022107 (2022)].

Optimization design of 3D-printed pyramid structure for broadband electromagnetic wave absorption

Aiming to improve the bandwidth of the absorber, which is more favorable for applications in military and civil fields, a novel FeSiAl/polylactic acid (PLA) composites pyramid was fabricated by fused deposition molding (FDM) 3D printing technology. The study investigated the impact of the geometric parameters of the unit structure on the absorption intensity and bandwidth of electromagnetic (EM) wave (EMW). The results show that the pyramid structure achieves a minimum reflection loss (RLmin) of − 37.2 dB. The cell structure of the pyramid structure features a period length of 22.5 mm, a base thickness of 0.5 mm, a cell thickness of 7.0 mm, and an upper surface edge length of 6.0 mm. These parameters result in a RL below − 10 dB within the frequency band of 6.7–18 GHz. Meanwhile, the effective absorption bandwidth (EAB, for RL below −10 dB) of TE polarization exceeds 11 GHz when the incident angle changes from 0° to 50°, and the EAB value of TM polarization still reaches 6.9 GHz at 70°. The broadband absorption properties of the proposed absorber are attributed to the synergistic enhancement effect of the structure and material.

On the Role of Kinetic Alfven Waves in the Magnetosheath Ion Thermalization Around the Night‐Side Magnetopause

AbstractThe solar wind ion transport across the magnetopause is one of the main sources of plasma for the Earth's magnetotail. Such a transport is supported by various dynamic processes at the flank magnetopause, where wave‐particle interactions play a crucial role in ion flow thermalization and diffusion across magnetic field surfaces of the magnetopause tangential discontinuity. In this paper we numerically model such ion thermalization by the most intense electromagnetic waves observed in the magnetosheath, kinetic Alfven waves. We aim to develop an approach for long‐term simulations of ion scattering by waves and ion dynamics around realistic magnetopause magnetic fields. This approach is based on a combination of test particle simulations and stochastic differential equations modeling ion diffusion in velocity space. We demonstrate that for realistic magnetopause configuration and wave characteristics, the magnetosheath ion flow can be substantially thermalized around the magnetopause. This result explains observations of ion energy conservation across the flank magnetopause: kinetic and thermal energies of flowing magnetosheath ions approximately equal to the thermal energy of stagnant magnetospheric ions.

A comment to improve tumor-treating fields therapy

&lt;abstract&gt; &lt;p&gt;Recent investigations have shown that special frequencies and intensities of electromagnetic waves could control the differentiations of some types of cells. Using this fact, tumor-treating fields (TTFields) therapy has been proposed as a technique which uses alternating electric fields of intermediate frequency (~100–500 kHz) and low intensity (1–3 V/cm) to disrupt the cell divisions of tumors. However, this technique may have harmful effects on ionic liquids around normal cells. For example, electrodes could induce an extra electrical current within blood vessels. To observe these effects, we connected electrodes to a slide that includes water and some extra ions and put them under a 1000× microscope. We found that some ions, microbes and cells move toward negative electrons and some go away. These attractions of cells by electrodes could cause the destruction of the brain. We also found some electrical currents within the liquid emerge which absorb or repel water molecules and induce some bubbles. If these types of bubbles arise within the blood vessels, they can exert a force on the membranes of normal cells and destroy them. To avoid these problems, we suggest that electrodes should be replaced by some electromagnetic sender/receiver which emits some special frequencies. These frequencies could be absorbed only by blood vessels around the tumors because these vessels may be created only to provide the needed food for tumor cells and thus have a different potential and electrical current as compared to vessels around normal cells. Thus, these tumor vessels could act as the antenna for TTFields.&lt;/p&gt; &lt;/abstract&gt;

Electromagnetic-Wave Mechanism of Formation and Propagation of Astrophysical Vortex Jets Generated in the Jumper of a Spiral Galaxy

An explanation of the mechanism of generation and acceleration of jets in outer space is given on the basis of experiments in the physics of electrical discharge. The presence of two arms in the spiral Galaxy gives grounds to assume that they have excess charges of the opposite sign. At the moment when the electric field strength between the tips of the arms becomes sufficient, an electrical breakdown occurs, which is accompanied by the movement of the current-plasma leader in the jumper between the tips of the arms. In the head part of the leader there is a flat electric domain of a strong field, which, during its inception, emits intense transverse electromagnetic waves in a direction perpendicular to the direction of the leader’s motion and to the plane of the accretion disk. The electric domain periodically appears and collapses due to the entry of neutral particles. Transverse electromagnetic waves capture charged particles from the discharge region and accelerate them in the direction of wave propagation. The crossed fields of an electromagnetic wave perform the functions of a multistage accelerator. The acceleration of the particles of the plasma produced in the discharge to relativistic energy values in the region of narrow vortex jets occurs under the action of forces caused by the components of the electromagnetic wave fields and the pressure gradient. The charged particles of a vortex jet acquire a significant rotational moment under the action of the Lorentz force. Explanations of the generation of microwave, bremsstrahlung and optical radiation from the region of the jumper between the arms of the Galaxy in the absence of electrical breakdown are also given.

The Motion of a Charged Particle in the Electromagnetic Field of a Polarization-Modulated Wave

This article presents an exact solution of the equation of motion of a charged particle in the electromagnetic field of a high-intensity polarization-modulated wave. Expressions for the average kinetic energy of a particle without regard to its rest energy in the case of circular and linear polarization of a modulated wave are obtained. The motion of a charged particle in the field was analyzed and expressed in terms of dependences of its average kinetic energy on the electromagnetic wave intensity and on various types of modulation depths. The contribution of each type of modulation to the energy characteristics of a charged particle was demonstrated. Solving the equation of motion of a charged particle in the electromagnetic field of a plane wave opens up possibilities for various applications related, in particular, to various developments of multi-frequency lasers and laser modulation technology. This study was proposed due to the growing interest in experiments using high-intensity femtosecond laser radiation and high-temperature plasma

N-doped carbon nanofiber embedded with TiN nanoparticles: A type of efficient microwave absorbers with lightweight and wide-bandwidth

In this work, TiN-embedded in N-doped carbon nanofiber (TiN/NCNF) composites were synthesized by the electrospinning method and heat treatment process subsequently. The TiN/NCNF composites possess different TiN nanoparticles (TiNNPs) content, which can acquire by tuning the percentage of TiNNPs in the polyacrylonitrile precursor solutions. The study shows that TiN/NCNF composites hold more intense and tunable electromagnetic wave (EMW) absorption capabilities, as the embedded TiNNPs with more defects lead to enhanced electrical conductivity and cause room-temperature ferromagnetic. As a result, TiN/NCNF composites can achieve the well-matched impedance and contribute to significant electromagnetic wave attenuation capabilities due to their more interfacial polarization, defect dipole relaxation polarization, enhanced conductance loss, and magnetic loss caused by the defect, resulting in excellent microwave absorbing performance. When the mass fraction of the TiN/NCNF composites (S2 sample with nominal 3 wt% TiNNPs content) was only 30% in the absorbing coating, the optimal reflection loss (RL) value was achieved in − 45.19 dB at 15.6 GHz with a thickness of 1.91 mm, corresponding efficient absorption bandwidth (RL≤−10 dB) of 4.93 GHz. This work provides a novel method of realizing lightweight, wide-bandwidth, and efficient microwave absorbing characteristics of carbon fiber absorbents, using obtained particles from defect engineering strategies as loaded ones. As may be expected, the TiN/NCNF composites would have a significant potential application prospect as microwave absorbing materials.

Detection of setting time during cement hydration using ground penetrating radar

The setting time of concrete needs to be detected to ensure the construction quality control. This research provides a new non-contact, nondestructive remote sensing detection method based on ground penetrating radar (GPR) for monitoring cement setting time. The moisture content of cement paste decreases during hydration, resulting in a change of its dielectric constant. Furthermore, dielectric permittivity affects the wave velocity and echo intensity of electromagnetic waves. Based on these characteristics, this paper utilizes GPR to measure the moisture content of cement paste in terms of changing dielectric permittivity, and then assess the setting time depending on the link between the moisture content and setting state of the cement paste. To detect an object smaller than one-wavelength, the full-waveform inversion is used to analyze the GPR echo data instead of the traditional velocity inversion measurement. The positive correlation between the reflection coefficient and dielectric constant is verified by both simulations and experiments. The experiment results accurately determine the initial and final setting time of cement paste, compared with the Vicat apparatus test. The method of GPR monitoring cement paste setting time based on full-waveform inversion theory can solve the quality control problems of concrete leveling automation and concrete layered construction automation.

Tunable transmission of a normal incidence through a double-slab structure

In this work, a double-slab structure is proposed, in which one slab is made of near-zero-real-part-of-impedance metamaterial (NZRPIM), and the other slab is made of ordinary transparent material. We shall demonstrate that, when a beam of electromagnetic wave is normally incident into the double-slab structure, the transmission may be enhanced significantly due to existence of a cross term induced by coherent superposition between forward and backward waves arising in the NZRPIM slab, thus the corresponding transmission peak may be strongly affected by the other slab and fluid arising between the two slabs, which is instructive significance for the design and application of high sensitivity refractive index sensor based on electromagnetic wave intensity detection. Our work may provide a new possible way to design and manufacture sensors by using NZRPIM.

Coherent backscatter enhancement in bistatic Ku- and X-band radar observations of dry snow

Abstract. The coherent backscatter opposition effect (CBOE) enhances the backscatter intensity of electromagnetic waves by up to a factor of 2 in a very narrow cone around the direct return direction when multiple scattering occurs in a weakly absorbing, disordered medium. So far, this effect has not been investigated in terrestrial snow in the microwave spectrum. It has also received little attention in scattering models. We present the first characterization of the CBOE in dry snow using ground-based and spaceborne bistatic radar systems. For a seasonal snowpack in the Ku-band (17.2 GHz), we found backscatter enhancement of 50 %–60 % (+1.8–2.0 dB) at a zero bistatic angle and a peak half-width at half-maximum (HWHM) of 0.25∘. In the X-band (9.65 GHz), we found backscatter enhancement of at least 35 % (+1.3 dB) and an estimated HWHM of 0.12∘ in the accumulation areas of glaciers in the Jungfrau–Aletsch region, Switzerland. Sampling of the peak shape at different bistatic angles allows estimating the scattering and absorption mean free paths, ΛT and ΛA. In the VV polarization, we obtained ΛT=0.4±0.1 m and ΛA=19±12 m at the Ku-band and ΛT=2.1±0.4 m and ΛA=21.8±2.7 m at the X-band, assuming an optically thick medium. The HH polarization yielded similar results. The observed backscatter enhancement is thus significant enough to require consideration in backscatter models describing monostatic and bistatic radar experiments. Enhanced backscattering beyond the Earth, on the surface of solar system bodies, has been interpreted as being caused by the presence of water ice. In agreement with this interpretation, our results confirm the presence of the CBOE at X- and Ku-band frequencies in terrestrial snow.

Probability density of irradiance for electromagnetic waves propagating through turbulent magnetized plasma

SummaryNumerous physical mediums can be modelled as turbulent magnetized plasma, for example, the solar corona, and the ionosphere. Scintillation effects on the intensity of electromagnetic beam wave propagating through magnetized plasma necessitate the introduction of a statistical distribution valid over a large range of scintillation conditions, and incorporating the plasma physical properties. Under some simplifying assumptions, such a theoretical model can be derived based on the Rytov solution, the external magnetic field variation, and the space permeating plasma electron density variation. The resultant wave intensity distribution is compared with the Lognormal, Rician, and the Nakagami distributions for different scintillations conditions. The work presented in this paper is applicable to the analysis and design of optical wireless communication links through the ionosphere and deep space plasma.

Light-Matter Interactions in Hybrid Material Metasurfaces.

This Review focuses on the integration of plasmonic and dielectric metasurfaces with emissive or stimuli-responsive materials for manipulating light-matter interactions at the nanoscale. Metasurfaces, engineered planar structures with rationally designed building blocks, can change the local phase and intensity of electromagnetic waves at the subwavelength unit level and offers more degrees of freedom to control the flow of light. A combination of metasurfaces and nanoscale emitters facilitates access to weak and strong coupling regimes for enhanced photoluminescence, nanoscale lasing, controlled quantum emission, and formation of exciton-polaritons. In addition to emissive materials, functional materials that respond to external stimuli can be combined with metasurfaces to engineer tunable nanophotonic devices. Emerging metasurface designs including surface-functionalized, chemically tunable, and multilayer hybrid metasurfaces open prospects for diverse applications, including photocatalysis, sensing, displays, and quantum information.

Marginal stability of whistler-mode waves in plasma with multiple electron populations

Whistler-mode waves are one of the most intense electromagnetic waves in the planetary magnetospheres. These waves are responsible for energetic electron losses into the atmosphere and for electron acceleration up to relativistic energies. Generation of whistler-mode waves is typically attributed to the thermal electron anisotropy. The anisotropy corresponding to the marginal stability for whistler-mode waves has been derived for a single-component Maxwellian plasma, but this criterion does not always work in the Earth's magnetosphere where whistler-mode waves are generated by an energy-confined, strongly anisotropic electron population. This study aims to generalize the marginal stability equation for multi-component plasma with a small, but strongly anisotropic, electron population. New analytical equations for the marginal stability have been derived from the linear analysis. We have also discussed applicability of the derived equations for different electron populations in the Earth's magnetosphere.