Emission Of Electromagnetic Waves Research Articles

Об электромагнитном излучении отдельных зарядов

The aim of the study is to establish the conditions for synchrotron radiation based on significant differences between tangential and centripetal accelerations of electric charges. From the fact that electromagnetic radiation carries away energy, it follows that the energy of the radiating system changes during radiation. Related to this is the following well-known rule: a change in energy is equal to work done. Three relevant theorems are proved. Theorem 1 states that a tangentially accelerated electric charge emits electromagnetic waves. Theorem 2 states that a normally accelerated electric charge does not emit electromagnetic waves. It is a well-known circumstance that the centripetal force does not perform work (since the scalar product of orthogonal vectors must be equal to zero). The proofs of Theorems 1 and 2 are performed in terms of forces. For electric charges, the transition to the terms of accelerations is carried out in accordance with Theorem 3which states that an electric charge satisfies Newton's second law. The tangential acceleration of an electric charge leads to the emission of electromagnetic waves. Generalization of the phenomenon of radiation to acceleration in general, including. normal charge acceleration, is false. The cause of synchrotron radiation should be sought in the tangential acceleration due to Coulomb interactions between the beam charges.

Self-Similarity of Continuous-Spectrum Radiative Transfer in Plasmas with Highly Reflecting Walls

Radiative Transfer (RT) in a continuous spectrum in plasmas is caused by the emission and absorption of electromagnetic waves (EM) by free electrons. For a wide class of problems, the deviation of the velocity distribution function (VDF) of free electrons from the thermodynamic equilibrium, the Maxwellian VDF, can be neglected. In this case, RT in the geometric optics approximation is reduced to a single transport equation for the intensity of EM waves with source and sink functions dependent on the macroscopic parameters of the plasma (temperature and density of electrons). Integration of this equation for RT of radio-frequency EM waves in laboratory plasmas with highly reflecting metallic walls is substantially complicated by the multiple reflections which make the waves with the long free path the dominant contributors to the power balance profile. This in turn makes the RT substantially nonlocal with the spatial–spectral profile of the power balance determined by the spatial integrals of the plasma parameters. The geometric symmetry of the bounding walls, especially when enhanced by the diffuse reflectivity, provides a semi-analytic description of the RT problem. Analysis of the accuracy of such an approach reveals an approximate self-similarity of the power balance profile and the radiation intensity spectrum in both approximate and ab initio modeling. This phenomenon is shown here for a wide range of plasma parameters and wall reflectivity, including data from various numeric codes. The relationship between the revealed self-similarity and the accuracy of numeric codes is discussed.

Computational Algorithms for the Study of Distributions with Electric Charge and Radiation Flux in General Relativity

The following research contributes to the understanding of how electric charge influences the unwrapping of spherically symmetric distributions using a relativistic approach. With the recent detection of gravitational waves and the location of black holes, where a strong emission of electromagnetic radiation prevails, interest has arisen to consider the existence of compact charged objects. Thus, the appearance of charge in small quantities during gravitational collapse, the process by which black holes originate, is not ruled out; this also includes the emission of electromagnetic waves from them. This article intends to establish algorithms and write field equations for a charged fluid as those corresponding to an anisotropic fluid with radiation flux. Using an appropriate definition of the mass function, considering self-similar symmetry and Bondian observers, dynamical results are obtained for the Einstein–Maxwell electromagnetic system with added gravity. Imposing an additional homothetic symmetry, the field equations are solved, and the most relevant conclusions are drawn about the influence of the electric charge during the collapse and subsequent changes in the physical variables.

IceCube-Gen2: the window to the extreme Universe

The observation of electromagnetic radiation from radio to γ-ray wavelengths has provided a wealth of information about the Universe. However, at PeV (1015 eV) energies and above, most of the Universe is impenetrable to photons. New messengers, namely cosmic neutrinos, are needed to explore the most extreme environments of the Universe where black holes, neutron stars, and stellar explosions transform gravitational energy into non-thermal cosmic rays. These energetic particles have millions of times higher energies than those produced in the most powerful particle accelerators on Earth. As neutrinos can escape from regions otherwise opaque to radiation, they allow an unique view deep into exploding stars and the vicinity of the event horizons of black holes. The discovery of cosmic neutrinos with IceCube has opened this new window on the Universe. IceCube has been successful in finding first evidence for cosmic particle acceleration in the jet of an active galactic nucleus. Yet, ultimately, its sensitivity is too limited to detect even the brightest neutrino sources with high significance, or to detect populations of less luminous sources. In this white paper, we present an overview of a next-generation instrument, IceCube-Gen2, which will sharpen our understanding of the processes and environments that govern the Universe at the highest energies. IceCube-Gen2 is designed to:(a) Resolve the high-energy neutrino sky from TeV to EeV energies(b) Investigate cosmic particle acceleration through multi-messenger observations(c) Reveal the sources and propagation of the highest energy particles in the Universe(d) Probe fundamental physics with high-energy neutrinosIceCube-Gen2 will enhance the existing IceCube detector at the South Pole. It will increase the annual rate of observed cosmic neutrinos by a factor of ten compared to IceCube, and will be able to detect sources five times fainter than its predecessor. Furthermore, through the addition of a radio array, IceCube-Gen2 will extend the energy range by several orders of magnitude compared to IceCube. Construction will take 8 years and cost about $350M. The goal is to have IceCube-Gen2 fully operational by 2033.IceCube-Gen2 will play an essential role in shaping the new era of multi-messenger astronomy, fundamentally advancing our knowledge of the high-energy Universe. This challenging mission can be fully addressed only through the combination of the information from the neutrino, electromagnetic, and gravitational wave emission of high-energy sources, in concert with the new survey instruments across the electromagnetic spectrum and gravitational wave detectors which will be available in the coming years.

Partial Discharge Detection of Multiple‐Narrow Band Antenna under the Radio Communication Noise

The ultra‐high frequency (UHF) method is attempted to diagnose the insulation condition of high voltage equipment as detecting partial discharge (PD) – emitted electromagnetic (EM) wave. Although the EM wave caused by PD has broadband, the UHF band includes many communication and broadcasting line spectral frequencies, which can affect PD detection as a noise. The authors have developed the multiple‐narrow band (MNB) antenna to detect discharge signals with high resistance against noisy line spectral frequencies. In this paper, the MNB antenna was applied to measure PD in SF6 gas and compared with a standard wide‐band Horn antenna to identify the PD detection ability. Furthermore, the MNB antenna was applied to measure PD signal in SF6 gas under the artificial and the real communication noise to estimate the noise elimination ability of MNB antenna. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Highly-efficient terahertz emission from hydrogen-bonded single molecular crystal 4-nitro-2,5-bis(phenylethynyl)aniline.

We report terahertz electromagnetic wave emission by optical rectification from hydrogen-bonded single molecular crystal 4-nitro-2,5-bis(phenylethynyl)aniline designed to be polar via the hydrogen bonding between nitroaniline cores. The terahertz emission efficiency is comparable to the representative inorganic terahertz emitter ZnTe. We show terahertz emission characteristics, optical spectrum, and theoretical molecular orbital calculations. Another three kinds of nitroaniline-based organic molecules are revealed to form polar crystal structure, and they have large hyperpolarizabilities and have potential for terahertz photonics.

Computational FEM Model and Phantom Validation of Microwave Ablation for Segmental Microcalcifications in Breasts Using a Coaxial Double-Slot Antenna.

Introduction Cancer is the second leading cause of death worldwide. Breast cancer is the second most common cause of cancer-related mortality, accounting for 11.6% of the total number of deaths. The main treatments for this disease are surgical removal of the tumor, radiotherapy, and chemotherapy. Recently, different minimally invasive technologies have been applied (e.g., emission of electromagnetic waves, thermal and chemical means) to overcome the important side effects of these treatment modalities. The objective of this study was to develop and evaluate a predictive computational model of microwave ablation. Materials and Methods The predictive computational model of microwave ablation was constructed by means of a dual-slot coaxial antenna. The model was compared with an experiment performed using a breast phantom, which emulates the dielectric properties of breast tissue with segmental microcalcifications. The standing wave ratio (SWR) was obtained for both methods to make a comparison and determine the feasibility of applying electromagnetic ablation to premalignant lesions in breasts. Specifically, for the analysis of segmental microcalcifications, a breast phantom with segmental microcalcifications was developed and two computational models were performed under the same conditions (except for blood perfusion, which was excluded in one of the models). Results The SWR was obtained by triplicate experiments in the phantom, and the measurements had a difference of 0.191 between the minimum and maximum SWR values, implying a change of power reflection of 0.8%. The average of the three measurements was compared with the simulation that did not consider blood perfusion. The comparison yielded a change of 0.104, representing a 0.2% change in power reflection. Discussion. Both experimentation in phantom and simulations demonstrated that ablation therapy can be performed using this antenna. However, an additional optimization procedure is warranted to increase the efficiency of the antenna.

Emission of electromagnetic waves as a stopping mechanism for nonlinear collisionless ionization waves in a high-β regime.

A high energy density plasma embedded in a neutral gas is able to launch an outward-propagating nonlinear electrostatic ionization wave that traps energetic electrons. The trapping maintains a strong sheath electric field, enabling rapid and long-lasting wave propagation aided by field ionization. Using 1D3V kinetic simulations, we examine the propagation of the ionization wave in the presence of a transverse MG-level magnetic field with the objective to identify qualitative changes in a regime where the initial thermal pressure of the plasma exceeds the pressure of the magnetic field (β>1). Our key finding is that the magnetic field stops the propagation by causing the energetic electrons sustaining the wave to lose their energy by emitting an electromagnetic wave. The emission is accompanied by the magnetic field expulsion from the plasma and an increased electron loss from the trapping wave structure. The described effect provides a mechanism mitigating rapid plasma expansion for those applications that involve an embedded plasma, such as high-flux neutron production from laser-irradiated deuterium gas jets.

Optimal synchronization of laser pulses in THz generation scheme with colliding plasma wakes

This paper discusses optimal conditions for setting up a laboratory experiment on the generation of narrow-band THz radiation due to the head-on collision of two plasma wakes excited by a pair of femtosecond laser pulses in a supersonic helium jet. In this case, emission of electromagnetic waves at the second harmonic of the plasma frequency is caused by nonlinear interaction of counterpropagating plasma waves having different transverse potential profiles in the focus of the laser beams. Using particle-in-cell simulations, we study how strongly the efficiency of laser-to-terahertz energy conversion in this scheme is affected by the inhomogeneous electron density profile arising during field ionization of helium, as well as by the time-delay between arrivals of laser pulses to the focal point.

Dark Area Classification From Airborne SAR Images Based on Deep Margin Learning

The dark area in the SAR image corresponds to the zero-energy electromagnetic echo region because specular reflection occurs when the emitted electromagnetic wave (EMW) comes into contact with a smooth object on the ground. In addition, EWM sometimes cannot measure the entire portion of the ground object due to the incident angle of the actual aperture radar sensor and the height of the object on the ground, which creates a dark area in the SAR image called a SAR shadow. Therefore, it is challenging to distinguish the dark area from shadows or some ground objects with smooth surfaces. To address this problem, this paper proposes a novel deep marginal learning algorithm (DMLA) to implement the dark zone classification of airborne SAR images. Specifically, a novel Snake Search Algorithm (SSA) with a chain code is deployed to generate margin slices of dark areas in SAR images, which is used as the input to the following classification network. In addition, a deep convolutional neural network with simple architecture is constructed to train the margin slices of the SSA, which outputs the final classification results with labels. Finally, experiments on three public airborne SAR image datasets output the average classification accuracy of 98.775% for the dark margin slices and an accuracy of 100% to identify dark regions in the original SAR images. The proposed method not only contributes to a high classification accuracy but also improves time efficiency.

Earthquake precursors in the light of peroxy defects theory: Critical review of systematic observations

Forecasting earthquakes implies that there are time-varying processes, which depend on the changing conditions deep in the Earth's crust prior to major seismic activity. These processes may be linearly or non-linearly correlated. In seismology, the research has traditionally focused on mechanical variables, including precursory ground deformation (revealing the build-up of stress deep below) and on prior seismic events (past earthquakes may be related to or even trigger future earthquakes). Since the results have been less than convincing, there is a general consensus in the seismology community that earthquake forecasting on time scales comparable to meteorological forecasts is still quite far in the future, if ever attainable. The starting point of the present review is to acknowledge that there are innumerable reports of other types of precursory phenomena observable on the ground or in near-Earth space ranging from the emission of electromagnetic waves from ultralow frequency (ULF) to near-infrared (NIR) and visible (VIS) light, electric field and magnetic field anomalies of various kinds (see below), all the way to widely reported but never fully understood unusual animal behavior. These precursory signals are intermittent and seem not to occur systematically before every major earthquake. As a result they are not widely accepted, because no one could fully explain their origins. In addition, the diversity of these signals makes them look unrelatable, hampering any progress. In the first part, we review evidence for a solid-state mechanism based on decades of research bridging semi-conductor physics, solid state chemistry and rock physics, that is capable of providing explanations for the diversity of reported pre-earthquake phenomena. In fact, it appears that all pre-earthquake phenomena might be traceable to a single fundamental process on the atomic scale: the rupture of peroxy bonds via activation of electronic charges, electrons and positive holes, in rocks subjected to tectonic stresses prior to seismic activity. The positive holes are defect electrons in the O2- sublattice. They are unusual inasmuch as they are able to flow out of the stressed rock volume, into and through the surrounding unstressed or less stressed rocks. They form electric currents that travel fast and far, causing along the way a wide range of physical and chemical follow-on processes: electrical ground potentials, stimulated infrared emission, massive air ionization, radon emanation, increased levels of ozone, toxic levels of carbon monoxide (CO) and more. In the second part, we critically examine satellite and ground station data, recorded before a selection of past large earthquakes. Some of the phenomena can be directly related to the peroxy defect theory, namely, radon gas emanations, corona discharges, thermal infrared emissions, air ionization, ion and electron content in the ionosphere, and electro-magnetic anomalies. Of course there is a need for further systematic investigations, continuing statistical examination of the relevance and confidence levels of the observable precursors. Only then will the scientific community be able to assess and eventually improve the performance of earthquake forecasts.

Mildly relativistic magnetized shocks in electron–ion plasmas – I. Electromagnetic shock structure

ABSTRACT Mildly relativistic shocks in magnetized electron–ion plasmas are investigated with 2D kinetic particle-in-cell simulations of unprecedentedly high resolution and large scale for conditions that may be found at internal shocks in blazar cores. Ion-scale effects cause corrugations along the shock surface whose properties somewhat depend on the configuration of the mean perpendicular magnetic field, that is either in or out of the simulation plane. We show that the synchrotron maser instability persists to operate in mildly relativistic shocks in agreement with theoretical predictions and produces coherent emission of upstream-propagating electromagnetic waves. Shock front ripples are excited in both mean-field configurations and they engender effective wave amplification. The interaction of these waves with upstream plasma generates electrostatic wakefields.

Aircraft position estimation using angle of arrival of received radar signals

With increasing demand of air traffic, there is a need to optimize the use of available airspace. Effective utilization of airspace relies on quality of aircraft surveillance. Active research is carried out for enhancements in surveillance techniques and various methods are evaluated for future use. This paper evaluates the use of multiple signal classification (MUSIC) based angle of arrival (AOA) estimation along with multiangulation for locating aircrafts from their electromagnetic wave emission. The performance evaluation of the system is presented by evaluating the AOA estimation errors and position estimation (PE) errors. The errors are evaluated by comparing the estimated value to the actual value. An analysis on the system parameters, AOA error and PE error are presented in the end. AOA errors are affected by the AOA value (emitter bearing), number of array elements, SNR and resolution of AOA estimation algorithm. Errors in AOA estimation lead to PE errors. The simulation results show small errors for short ranges. The system performance can be improved at the expense of computational time by using higher MUSIC resolution and larger antenna arrays

Rotational coherence of encapsulated ortho and para water in fullerene-C60 revealed by time-domain terahertz spectroscopy

We resolve the real-time coherent rotational motion of isolated water molecules encapsulated in fullerene-C60 cages by time-domain terahertz (THz) spectroscopy. We employ single-cycle THz pulses to excite the low-frequency rotational motion of water and measure the subsequent coherent emission of electromagnetic waves by water molecules. At temperatures below ~ 100 K, C60 lattice vibrational damping is mitigated and the quantum dynamics of confined water are resolved with a markedly long rotational coherence, extended beyond 10 ps. The observed rotational transitions agree well with low-frequency rotational dynamics of single water molecules in the gas phase. However, some additional spectral features with their major contribution at ~2.26 THz are also observed which may indicate interaction between water rotation and the C60 lattice phonons. We also resolve the real-time change of the emission pattern of water after a sudden cooling to 4 K, signifying the conversion of ortho-water to para-water over the course of 10s hours. The observed long coherent rotational dynamics of isolated water molecules confined in C60 makes this system an attractive candidate for future quantum technology.

SCF-NiFe2O4/epoxy composites with high thermal conductivity and electromagnetic interference resistance

With the development of electronic components towards high power, high packaging density, and miniaturization of device size, heat dissipation and the electromagnetic interference problems between the electronic components are emerging. In order to solve the undesirable electromagnetic wave and heat emissions produced by electronic device simultaneously, the electronic packaging materials with high thermal conductivity and anti-electromagnetic interference are highly expected. In this work, NiFe2O4-modified short carbon fibers (SCF) were designed and prepared. NiFe2O4 were in situ grown on the surface of SCF by hydrothermal method. The chemical structure and morphology of SCF-NiFe2O4 were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The microwave absorbing performance test shows that SCF-NiFe2O4 possess superior microwave absorbing performance, where the minimum reflection loss is − 20.7 dB. Finally, SCF-NiFe2O4/epoxy resin composites were prepared by introducing SCF-NiFe2O4 as thermal conductive filler into epoxy resin. The surface-modified SCF with NiFe2O4 is more easily infiltrated by resin and exhibits strong interfacial interaction with the matrix. With the increase of the content of SCF-NiFe2O4, the thermal conductivity of the composites increases obviously. When the content of SCF-NiFe2O4 reaches 20 vol%, the composites show better thermal conductivity, and the thermal conductivity reaches 1.03 W/m K.

PIC Simulations of Microinstabilities and Waves at Near-Sun Solar Wind Perpendicular Shocks: Predictions for Parker Solar Probe and Solar Orbiter

Abstract Microinstabilities and waves excited at moderate-Mach-number perpendicular shocks in the near-Sun solar wind are investigated by full particle-in-cell simulations. By analyzing the dispersion relation of fluctuating field components directly issued from the shock simulation, we obtain key findings concerning wave excitations at the shock front: (1) at the leading edge of the foot, two types of electrostatic (ES) waves are observed. The relative drift of the reflected ions versus the electrons triggers an electron cyclotron drift instability (ECDI) that excites the first ES wave. Because the bulk velocity of gyro-reflected ions shifts to the direction of the shock front, the resulting ES wave propagates oblique to the shock normal. Immediately, a fraction of incident electrons are accelerated by this ES wave and a ring-like velocity distribution is generated. They can couple with the hot Maxwellian core and excite the second ES wave around the upper hybrid frequency. (2) From the middle of the foot all the way to the ramp, electrons can couple with both incident and reflected ions. ES waves excited by ECDI in different directions propagate across each other. Electromagnetic (EM) waves (X mode) emitted toward upstream are observed in both regions. They are probably induced by a small fraction of relativistic electrons. Results shed new insight on the mechanism for the occurrence of ES wave excitations and possible EM wave emissions at young coronal mass ejection–driven shocks in the near-Sun solar wind.

Quantum mass of an electron in the hydrogen atom derived from the relativistically modified Schrödinger equation

In Bohr's theory, the photon emission or absorption by the hydrogen atom is expressed by the frequency condition. In the hydrogen atom, the eigenvalue of energy derived from the relativistically modified Schrödinger equation contains the quantum mass of an electron. The frequency condition is explained using this mass. The electromagnetic wave (e.g., X rays) emission from the highly accelerated free electron was thus predicted from this mass.

Convolutional Neural Networks for Spectroscopic Redshift Estimation on Euclid Data

In this paper, we address the problem of spectroscopic redshift estimation in Astronomy. Due to the expansion of the Universe, galaxies recede from each other on average. This movement causes the emitted electromagnetic waves to shift from the blue part of the spectrum to the red part, due to the Doppler effect. Redshift is one of the most important observables in Astronomy, allowing the measurement of galaxy distances. Several sources of noise render the estimation process far from trivial, especially in the low signal-to-noise regime of many astrophysical observations. In recent years, new approaches for a reliable and automated estimation methodology have been sought out, in order to minimize our reliance on currently popular techniques that heavily involve human intervention. The fulfilment of this task has evolved into a grave necessity, in conjunction with the insatiable generation of immense amounts of astronomical data. In our work, we introduce a novel approach based on Deep Convolutional Neural Networks. The proposed methodology is extensively evaluated on a spectroscopic dataset of full spectral energy galaxy distributions, modelled after the upcoming Euclid satellite galaxy survey. Experimental analysis on observations of idealistic and realistic conditions demonstrate the potent capabilities of the proposed scheme.

Theory of electromagnetic wave (≥1 mm) emission and absorption by the hydrogen atom derived from the relativistically modified Schrödinger equation

The relativistically modified Schrödinger equation is solved for the hydrogen atom for consistency with the eigenvalues of electron’s energy derived from the Dirac equation. Based on the consistency of their eigenvalues, the theory of electromagnetic wave (≥1 mm) emission and absorption by the hydrogen atom is expressed. Another particle in addition to an electron is predicted from this theory.

Novel particle-based model of negative corona in oxygen for investigation on emission of electromagnetic waves

In recent years, the ultrahigh frequency (UHF) partial discharge (PD) measurement technique has gained more attention as an effective approach towards condition monitoring of power transformers. In this contribution, a novel model for the simulation of negative corona, based on particles' movement, is presented and implemented in COMSOL Multiphysics. Unlike existing models of PD, this model aims at an accurate representation of the phenomenon from an electromagnetic (EM) viewpoint. Following a discussion on the theoretical fundamentals of PD, the model containing the mechanisms and processes that occur during the PD phenomenon and lead to propagation of EM waves is discussed. Subsequently, simulation results are analyzed and previously ambiguous properties of negative corona are interpreted and some efforts are done to validate the theory using experimental measurement.