Generation Of Electromagnetic Radiation Research Articles

Using a New Phenomenon of Electronic Oscillations Near the Positive Electrode to Generate Powerful Microwave Radiation

A novel microwaves generator scheme is introduced, where electrons perform oscillations within the electric field of a positively charged electrode. This phenomenon is based on a recently developed theory of the interaction of electrons with electric fields, which predicts the presence of a repulsive force acting on an electron near strongly positively charged bodies. Along with the usual attractive force acting at a distance, this newly discovered repulsive force causes specific oscillations of electrons in the vicinity of a positively charged electrode, leading to the generation of electromagnetic radiation. The proposed generator represents a new variant of a vircator, wherein a virtual cathode is formed in front of, rather than behind, a positively charged anode.

Optimization of Electro-Optic Sampling by Photodiode's Choice for Terahertz Detection

Despite being widely used in a lot of measurements involving the generation of electromagnetic radiation, most of the optimization of this EOS technique only focused on the detection crystal and nonlinear coefficient of the said crystal. After the detection crystal, the combined pump-probe beam should be separated again based on its polarization and measured simultaneously with photodiodes. The authors found out that there are not many studies focusing on this part of the EOS technique and decided to present in this paper to contribute to the better optimization of detection with the EOS technique. We found out that the change of photodiode could have a relationship with the detected signal’s shape in the time and space domain, alongside the change of delay-time detection.

Optimization of Electro-Optic Sampling by Photodiode's Choice for Terahertz Detection

Despite being widely used in a lot of measurements involving the generation of electromagnetic radiation, most of the optimization of this EOS technique only focused on the detection crystal and nonlinear coefficient of the said crystal. After the detection crystal, the combined pump-probe beam should be separated again based on its polarization and measured simultaneously with photodiodes. The authors found out that there are not many studies focusing on this part of the EOS technique and decided to present in this paper to contribute to the better optimization of detection with the EOS technique. We found out that the change of photodiode could have a relationship with the detected signal’s shape in the time and space domain, alongside the change of delay-time detection.

Development of barium hexaferrite core–shell composites as high-performance microwave absorption by optimizing hydrothermal synthesis

In conjunction with the enhancement of societal living standards and the rapid development of information technology, an extensive variety of high-capacity electronic devices are being introduced to the market. The heightened demands result in the generation of electromagnetic wave radiation, which poses a potential risk to human well-being. Barium hexaferrite (BHF) is one of the radar-absorbing materials (RAMs) that can absorb electromagnetic waves because it has a high anisotropic field. However, its drawbacks are narrow absorption and less stability. Molybdenum disulfide (MoS2), is the best candidate for the reinforcement of BHF. The study investigated the impact of increasing the thiourea, temperature, hydrothermal holding time, and sample thickness on reflection loss. This study used a two-step molten salt and hydrothermal synthesis to make a BaFe12O19@MoS2 core-cell composite. Two-step molten salt and hydrothermal synthesis methods created single-phase BaFe12O19@MoS2 core-cell composites that worked well. The results showed that adding MoS2 to BHF changed BHF's magnetic properties from hard to soft. Increasing the hydrothermal temperature up to 220 °C effectively reduced the reflection loss of BaFe12O19@MoS2. On a 2 mm thick sample containing 100 mmol thiourea, the study achieved an electromagnetic wave absorption of 99.97 % with a reflection loss of –35.41 dB (17.37 GHz). The results of this research can be applied to protect electronic devices vulnerable to signal interference from satellite radar systems at frequencies of 12–18 GHz

Automatic Recognition of Vertical-Line Pulse Train from China Seismo-Electromagnetic Satellite Based on Unsupervised Clustering

Pulse signals refer to electromagnetic waveforms with short duration and high peak energy in the time domain. Spatial electromagnetic pulse interference signals can be caused by various factors such as lightning, arc discharge, solar disturbances, and electromagnetic disturbances in space. Pulse disturbance signals appear as instantaneous, high-energy vertical-line pulse trains (VLPTs) on the spectrogram. This paper uses computer vision techniques and unsupervised clustering algorithms to process and analyze VLPT on very-low-frequency (VLF) waveform spectrograms collected by the China Seismo-Electromagnetic Satellite (CSES) electric field detector. First, the waveform data are transformed into time–frequency spectrograms with a duration of 8 s using the short-time Fourier transform. Then, the spectrograms are subjected to grayscale transformation, vertical line feature extraction, and binarization preprocessing. In the third step, the preprocessed data are dimensionally reduced and fed into an unsupervised K-means++ clustering model to achieve automatic recognition and labeling of VLPTs. By recognizing and studying VLPT, not only can interference be recognized, but the temporal and spatial locations of these interferences can also be determined. This lays the foundation for identifying VLPT sources and gaining deeper insights into the generation, propagation, and characteristics of electromagnetic radiation.

The danger of ball lightning

Ball lightning in close contact with living beings can strike them with electric current or high-frequency radio emission. The current, passing through the surface of the skin, can cause it to burn. The entry of current into the region of the heart or the respiratory center of the brain can lead to death. High-frequency radio emission from ball lightning occurs in the wavelength range of 1-10 cm and can be absorbed by liquid water. When ball lightning comes into close contact with the body, blood heating and muscle rupture can occur. Cases of the indicated action of ball lightning on people are given. It is shown that the charge of ball lightning can be kept in a shell consisting of polarized water molecules. The reason for the generation of electromagnetic radiation of ball lightning is the cyclic movement of electrons in closed orbits. The radiation power sharply increases when the uniform distribution of electrons along the orbit is violated. It had been proven that dashed traces that appear on photographic films during electrical discharges in water are created by the action of multiply charged clusters having the structure of ball lightning. These clusters can penetrate the skin into living organisms and remain in them for a long time. The biological effect of these clusters has not yet been studied, but there is evidence that they are hazardous to health (causing cancer and liver damage).

Vacuum Arcs on Solar Array Surfaces

Arcs on the solar arrays appear to be the most plausible source for the electromagnetic radiation observed with the Arecibo radio telescope. In the laboratory, electrostatic discharges (arcs) on solar array coupons were studied in a simulated geosynchronous equatorial orbit environment. Arc current pulses were recorded with a high time resolution (up to 0.2 ns). Spectral properties of these pulses demonstrated no monotonic behavior but rather separated peaks within the frequency range of 100–1000 MHz. Electromagnetic radiation from these arcs was registered and recorded with a Yagi antenna 8 m distant from the arc site, and a high-speed oscilloscope. Analysis of the spectra resulted in the discovery of well-separated “lines.” Evaluation of arc current spectra and radio-frequency spectra revealed statistically significant patterns in the frequency domain. Measured radio fluxes and theoretical estimates of the power of electromagnetic radiation from arcs on spacecraft solar arrays strongly argue in favor of the arcing hypothesis for the source of this radiation. These results have enabled considerable progress to be made in understanding the physical nature of the generation of electromagnetic radiation by transient vacuum discharges.

Electromagnetic radiation of semiconductor crystals in crossed electric and magnetic fields

The features of generation of electromagnetic radiation by semiconductor crystals in crossed electric and magnetic fields have been analyzed. Analytical relations for calculating the power of cyclotron radiation have been given. The obtained results are of interest for the purposes of obtaining the sources of electromagnetic radiation in the terahertz frequency range.

X-Ray and Gamma Radiation of Lightning Discharge: Orbital Observations and Laboratory Simulation in Experiments with Long Sparks

Problems associated with observations and interpretation of the physical mechanisms underlying the generation of hard electromagnetic radiation from lightning discharges are considered. A review of modern problems of understanding the nature of atmospheric flashes of gamma radiation from the Earth’s atmosphere is given. The results of orbital observations, in particular, on the Vernov satellite, are analyzed. The possibilities of orbital observations of atmospheric gamma-ray flashes on CubeSat spacecraft are discussed, and a description of the recording equipment is given. The technique of a laboratory experiment with long sparks, which simulates electrical discharges in thunderclouds, is considered.

Research on Electromagnetic Radiation Mechanism during Detonation of Energetic Material.

In the process of deflagration of energetic materials, strong electromagnetic radiation is generated, which causes the surrounding electronic equipment to fail to work normally. To solve this problem, it is necessary to clarify the mechanism of electromagnetic radiation generated by energetic materials. The mechanism of plasma changed by the deflagration of energetic materials is an important topic in the aerospace and geophysics fields. The academic community holds two main viewpoints on the mechanism of electromagnetic radiation generated by energetic materials: one is that the solid material is squeezed and deformed during the deflagration of energetic materials, and the charges of different polarities rub in space to form effective electric dipoles, which eventually generate electromagnetic radiation. Another view is that the deflagration of energetic materials causes the temperature of the medium to rise sharply, and bremsstrahlung is formed during the compression and diffusion of the high-temperature wave front, resulting in the generation of electromagnetic radiation. This paper, based on theoretical analysis and experimental data, holds the view that electromagnetic radiation is generated by the high-temperature thermal effect. It studies the relationship between temperature and electromagnetic radiation and obtains quantitative analysis conclusions.

40 year anniversary of the RADAN systems – compact pulsed power sources for various investigations

This article includes a brief overview of the compact RADAN-series subgigawatt pulsed voltage sources and describes their capabilities in various electrophysical researches. We present the results obtained in the experiments at nano- and subnanosecond time scales on the formation of the voltage pulses with a special shape, electron beams emission in air gaps and by the cold cathodes in vacuum, as well as generation of electromagnetic radiation. Particular attention is paid to the promising application of the RADAN systems.

Time-Frequency Characteristics and the Influence Mechanism of the EMR from Coal with Different Joint Angles

It is vital to understand the electromagnetic radiation’s time-frequency characteristics in the process of coal and rock failure with different joint angles in order to reveal the generation mechanism of the electromagnetic radiation (EMR) and improve the accuracy of EMR early warning. We studied the time-frequency characteristics of EMR signals of coal samples with different joint angles. The study finds that, (1) with the increase of joint angle, the failure time and peak load of samples decrease first and increase later, and the postpeak failure time decreases gradually. The EMR counts’ peak value showed a slow rise, a sharp rise, and a slow rise in the three intervals of α = 0° to 45°, 45° to 60°, and 60° to 90°, respectively. The accumulated EMR counts showed a steady upward trend. The duration of the EMR waveform, the dominant frequency of the EMR, and the peak number of the frequency spectrum of coal samples are on the rise. (2) As the joint angle increases, the samples’ failure mode changes from the stage fracture dominated by tension cracks to the rapid fracture with the coexistence of shear and tension cracks and finally to the burst fracture which produces a large number of fragments. This is also the main reason for the difference of the EMR generation mechanism and the signal of samples with different joint angles. (3) According to the experimental results, we established the modified formulas for calculating the EMR threshold value and deviation of coal and rock with joints under different stress environments and revealed that the longer the EMR waveform duration, the higher the dominant frequency, and the more the number of spectrum peaks, the greater the burst risk of coal and rock.

FLAP Collaboration: Tasks and Perspectives. Study of Fundamentals and New Applications of Controllable Generation of Electromagnetic Radiation by Relativistic Electrons Using Functional Materials

We present the scope of research of a new collaboration FLAP (Fundamental & applied Linear Accelerator Physics collaboration) devoted to the study of the basics of electromagnetic interactions and new applications of controllable generation of electromagnetic radiation by relativistic electrons using functional materials.

Electromagnetic microwave generation by acoustic vibrations gives rise to nanoradiophotonics

The development of new methods for generating pulsed electromagnetic microwave radiation is currently an actively developing area of research. Schemes for microwave radiation generation with optical pumping are of great interest. In this paper we propose and experimentally demonstrate principally new method for photonic generation of microwave electromagnetic radiation. This method is based on the use of radiation of charged submicron particles oscillating at their own acoustic frequency. Laser radiation of the optical range implements an effective buildup of acoustic vibrations of submicron particles forming the system under study, according to the Raman mechanism.

Radiation instability of a relativistic electron beam moving in a split resonator

In this paper, we considered the radiation instability in a split asymmetric resonator for the relativistic case assuming the space charge of the beam. In the small-signal approximation, expressions for the energy loss by a particle passing through the resonator and for the beam current modulation are obtained. Based on analytical and numerical calculations, it is shown that the symmetric configuration provides the highest growth rate of instability. It is found that with the increase of the initial electron energy, the modulation of the beam current as well as the efficiency of the energy transfer from particles to the electromagnetic field decrease. The increase of the beam density has a positive effect on the radiation instability. The results obtained have to be taken into account when developing generators of electromagnetic radiation or a system for modulating the beam current based on a split resonator.

Generation of intense coherent electromagnetic radiation during the interaction of a multi-terawatt laser pulse with a nanowire target* *Reported at the 4th International Conference on Ultrafast Optical Science (Russia, Moscow, FIAN, 28 September – 2 October 2020).

Generation of coherent radiation in the IR and terahertz ranges during the propagation of a multi-terawatt laser pulse along a nanowire target is investigated. In the process of interaction, dense electron bunches are displaced from the target and accelerated in the laser field, generating intense electromagnetic radiation. Three regimes of interaction can be realised depending on the duration and shape of the laser pulse. In the first regime, when the laser pulse is long enough (tens and hundreds of femtoseconds), electrons are only partially forced out of the target. The characteristics of the low-frequency part of the spectrum of the generated radiation are determined in this case by the duration of the laser pulse, as well as by its amplitude and target parameters (geometric dimensions and concentration of electrons). In the second regime, the laser pulse has a large amplitude and a steep rising edge (the amplitude of the first half-wave is of the order of the maximum pulse amplitude); as a result, most of the electrons are displaced from the target already at the initial moment of interaction. In this regime, unipolar and bipolar pulses with a duration of tens of laser field periods can be formed. Changing the target length makes it possible to control the period of field oscillations and their number in the generated radiation. In the intermediate regime of short laser pulses with an insufficiently steep rising edge, oscillations of the formed electron bunches can occur in the macroscopic Coulomb attraction field of the charged target, which gives rise to radiation with a frequency several times lower than that of laser radiation. In this case, the pulses of the generated radiation contain a few cycles of the field with decreasing amplitude and increasing frequency. Using numerical simulation in three regimes of interaction, the characteristics of IR and terahertz radiation are found, in particular, the pulse shapes, ranges of generated frequencies, amplitudes and angular distributions of radiation are determined. It is shown that the amplitude of the generated pulse can reach subrelativistic and relativistic values (the field strength is more than 1 TV m−1 at a frequency ten times lower than the laser radiation frequency), and the energy conversion efficiency can be of the order of one percent.

The Role Of Quantum Electronics In Alternative Energy

The article deals with Quantum electronics, as a field of physics that studies methods of amplification and generation of electromagnetic radiation based on the phenomenon of stimulated radiation in nonequilibrium quantum systems, as well as the properties of amplifiers and generators obtained in this way and their application, a description of the structure of the most important lasers is given, physical foundations of quantum electronics, which are reduced primarily to the application of Einstein's theory of radiation to thermodynamically nonequilibrium systems with discrete energy levels. The article is intended for undergraduates of the Department of Physics, Radio Engineering, who have interests in the field of research and applications of laser radiation, and is aimed at giving them the minimum necessary for that initial information on quantum electronics.

Diffractive shadowing of coherent polarization radiation

We report on the study of shadowing of electromagnetic fields radiated in the Terahertz (THz) region from two consecutive sources of coherent diffraction and transition radiation. In these conditions, the formation length is predicted to be ≲100 m, and shadowing effects should result in an almost complete suppression of radiated fields within distances of the order of tens of centimeters. We experimentally measured that shadowing effects disappear for distances significantly shorter than those predicted. We propose a new model that explains our experimental observations by taking into account 3D diffraction effects. These findings will have a positive impact on the beneficial use of consecutive radiators both for the generation of intense electromagnetic radiation and for beam diagnostics using coherent polarization radiation from ultra-relativistic charged particles.

Terahertz Scanning Reflectometer for Structure Visualization of Polymer Constructions in Additive Manufacturing

The results of the development and practical application of a quasi-optical system for reflectometry of objects in the terahertz frequency range for analyzing the structure in additive manufacturing of objects are presented. A backward-wave oscillator is used for continuous generation of electromagnetic radiation; an acousto-optic converter (Golay cell) is applied as a detector. The reflectometer is controlled by personal computer through the L-card E 154 input-output module and the standard digital-to-analog converter of the STD-21 spectrometer. The system is tested at the frequency of 874 GHz on the 3D-printed composite structure sample. Our paper is terahertz reflectometer with a source of continuous monochromatic electromagnetic radiation based on a backward wave oscillator is presented. The purpose of this work in creating a scanning THz reflectometer is considered to have been achieved. At the same time, the following tasks are solved: a quasi-optical scheme of the reflectometer is selected and assembled; the hardware part of the system (all mechanisms and components) is implemented; a program for controlling the radiation intensity registration system is adapted for this task; the test sample is manufactured using 3D printing technology, the THz reflectometer is tested. The obtained practical results of registration of the two-dimensional distribution of the reflection coefficient show that the use of THz radiation is promising for visualizing the structure of structures obtained by additive technology. Further development of the project is planned by changing the construction of the positioning mechanism, which will provide micrometric calibration of the sample holder relative to the diaphragm. The use of the quasi-optical scheme of the two-beam interferometer for recording the phase distribution and amplitude of reflected THz radiation will allow obtaining information about the spatial location of defects (inhomogeneities) of products obtained by additive technology.

Electromagnetic radiation detection in cement-mortar/lead zirconate titanate composites using drop-weight impact technique

Investigation on the electromagnetic radiation (EMR) emission from cement-mortar/lead zirconate titanate (cement-mortar/PZT) composites using a drop-weight impact technique has been undertaken to explore its possible applications in civil structures as a sensor. Unpoled soft grade PZT (SP-5A) powder, having a particle size of 1 µm is used for preparing the cement-mortar/PZT composite samples onto which the experiments were conducted in unpoled state. The EMR generation from cement-mortar/PZT composites is due to the accelerated movement of the charged particles in the pores of hydrated cement and due to oscillations of dipoles in the PZT. The values of EMR voltage, the average release rate of EMR energy, and dominant frequency are observed to increase with the rise of the PZT content and the height of impact. The deformation/strain in the composite could be sensed by measuring the EMR voltage. Also, the addition of PZT in mortar results in an increase in the compressive strength and bulk density and a decrease in the porosity of the composite. The effect of the separation of the antenna and the composite samples on the EMR voltage has also been studied. The results obtained, foreshadow the prospect of the present non-destructive technique, a better option for structural health monitoring.