Propagation Of Electromagnetic Pulses Research Articles

A Finite-Difference Scheme for the One-Dimensional Maxwell Equations

This paper deals with a difference scheme of second-order approximation using Laquerre transform for the one-dimensional Maxwell equations. Supplementary parameters are introduced into this difference scheme. These parameters are obtained by minimizing the error of a difference approximation for a Helmholtz equation. The optimal parameters do not depend on the step size and the number of nodes in the difference scheme. It is shown that the use of the Laguerre decomposition method allows obtaining higher accuracy of approximation of the equations in comparison with similar difference schemes when using the Fourier decomposition method. The second-order finite difference scheme with the parameters is compared to a fourth-order difference scheme in two cases: The use of the optimal difference scheme when solving a problem of electromagnetic pulse propagation in an inhomogeneous medium yields a solution accuracy comparable to that obtained with the fourth-order difference scheme. When solving an inverse problem the second-order difference scheme allows obtaining higher solution accuracy as compared to the fourth-order difference scheme. In these problems the second-order difference scheme with the supplementary parameters has decreased the calculation time by 20–25% as compared to the fourth-order difference scheme.

Features of the Propagation of a Solitary Electromagnetic Wave in a Two-Dimensional Graphene-Based Superlattice

An equation is obtained for describing the propagation of electromagnetic waves in a two-dimensional grapheme-based superlattice in a collisionless approximation. The effect a high-frequency electric field and the nonadditivity of the energy spectrum have on the propagation of a solitary electromagnetic pulse in arbitrary directions inside a sample is determined. The soliton–electric current and charge carried away by a soliton are calculated.

Laser produced electromagnetic pulses: generation, detection and mitigation

This paper provides an up-to-date review of the problems related to the generation, detection and mitigation of strong electromagnetic pulses created in the interaction of high-power, high-energy laser pulses with different types of solid targets. It includes new experimental data obtained independently at several international laboratories. The mechanisms of electromagnetic field generation are analyzed and considered as a function of the intensity and the spectral range of emissions they produce. The major emphasis is put on the GHz frequency domain, which is the most damaging for electronics and may have important applications. The physics of electromagnetic emissions in other spectral domains, in particular THz and MHz, is also discussed. The theoretical models and numerical simulations are compared with the results of experimental measurements, with special attention to the methodology of measurements and complementary diagnostics. Understanding the underlying physical processes is the basis for developing techniques to mitigate the electromagnetic threat and to harness electromagnetic emissions, which may have promising applications.

Estimation of sand water content using GPR combined time-frequency analysis in the Ordos Basin, China

Abstract Groundwater is the key factor of determining the growth of vegetation. Identifying the characteristics of groundwater is an important basis to formulate a management plan for water resources and develop the technology of controlling desertification in arid areas scientifically. It is also important to the environmental protection in China. Ground penetrating radar (GPR) signals produce a special response to the changes in water content during propagation, thus it is essential to study the propagation of electromagnetic pulse in aeolian sand with different water content. The GPR tests of aeolian sand samples with different water content were conducted by a GPR system, dielectric constant meter, and conductivity meter. The temporal and frequency spectral characteristics of electromagnetic signals measured from aeolian sand samples were analyzed. The results show that the dielectric constant and conductivity of aeolian sand increase nonlinearly as the water content increases, and the attenuation coefficient of electromagnetic pulses increases parabolically. Meanwhile, the temporal waveform fluctuates significantly at the boundary of different media, and its two-way travel time increases nonlinearly as the water content increases, the pulse velocity decreases nonlinearly. Furthermore, the peak frequency of the spectrum for a signal propagating through aeolian sand decreases as the water content increases. The peak frequency is concentrated in the 1000 to 1400 MHz range, but the shape and bandwidth of the spectrum are less affected by water content. The above-mentioned correlations can provide a water content estimation of aeolian sand with direct value to the local authorities which are involved in the decision-making process for effective water management in arid and semi-arid area.

Analysis of electromagnetic pulses generation from laser coupling with polymer targets: Effect of metal content in target

Powerful lasers interacting with solid targets can generate intense electromagnetic pulses (EMPs). In this study, EMPs produced by a pulsed laser (1 ps, 100 J) shooting at CH targets doped with different titanium (Ti) contents at the XG-III laser facility are measured and analyzed. The results demonstrate that the intensity of EMPs first increases with Ti doping content from 1% to 7% and then decreases. The electron spectra show that EMP emission is closely related to the hot electrons ejected from the target surface, which is confirmed by an analysis based on the target–holder–ground equivalent antenna model. The conclusions of this study provide a new approach to achieve tunable EMP radiation by adjusting the metal content of solid targets, and will also help in understanding the mechanism of EMP generation and ejection of hot electrons during laser coupling with targets.

Effect of expanding plasma on propagation of electromagnetic pulses by laser-plasma interaction

Experiments were performed using the Prague Asterix Laser System to study the effect of expanding plasma on electromagnetic pulse propagation (EMP) in the interaction chamber in an intensity regime of 1016 W cm−2. Similar to the interaction that occurs between radio waves and the ionosphere, the expansion of laser-produced plasma causes the vacuum chamber to be gradually filled with inhomogeneous plasma that interacts with the emitted EMP. Combining the space-time analysis of a plasma density inside the interaction chamber and the fast Fourier transform filtering of antenna signals, we have resolved the influence of the expanding plasma on space-time characteristics of EMP.

X‐ray Signatures of Lightning‐Induced Electron Precipitation

AbstractWe present detailed numerical modeling to predict expected X‐ray signatures from lightning‐induced electron precipitation (LEP) events. Simulations include the transionospheric propagation of the lightning electromagnetic pulse; ray tracing through the magnetosphere, including Landau damping; wave‐particle interactions resulting in loss cone fluxes; and Monte Carlo simulation of the electron precipitation process, including bremsstrahlung photon production and propagation to a balloon observing platform. Modeling is included to show that our simulated events are consistent with subionospheric very low frequency observations of LEP. Simulations show that these events should be observable from balloon‐based platforms. The modeled LEP event signatures, including X‐ray flux, spectrum, and pulse shape, are then compared with observations of energetic X‐ray pulses from the Balloon Array for Radiation‐belt Relativistic Electron Losses 1U balloon taken in January 2013 and are shown to be highly consistent with the observations. The pulses were observed near , while the balloon was off the coast of Antarctica at about 70°S, 5–20°W. Correlations with GOES imagery and global lightning data, together with analysis of the temporal and spectral signatures of these pulses, led to the initial suggestion that these events could be signatures of LEP. However, for only a fraction of these events could a causative lightning discharge be identified in global lightning data sets. This poor correlation may be partially attributed to causative strokes being missed by the global lightning networks; nonetheless, we discuss other possible explanations for these events.

Asymptotic dynamics of three-dimensional bipolar ultrashort electromagnetic pulses in an array of semiconductor carbon nanotubes.

We study the propagation of three-dimensional bipolar ultrashort electromagnetic pulses in an array of semiconductor carbon nanotubes at times much longer than the pulse duration, yet still shorter than the relaxation time in the system. The interaction of the electromagnetic field with the electronic subsystem of the medium is described by means of Maxwell's equations, taking into account the field inhomogeneity along the nanotube axis beyond the approximation of slowly varying amplitudes and phases. A model is proposed for the analysis of the dynamics of an electromagnetic pulse in the form of an effective equation for the vector potential of the field. Our numerical analysis demonstrates the possibility of a satisfactory description of the evolution of the pulse field at large times by means of a three-dimensional generalization of the sine-Gordon and double sine-Gordon equations.

A Research on Electronic Component Wrecker Using Electro-Magnetic Pulse (EMP)

An EMP (Electro-Magnetic Pulse) has the destructive tendency to destroy any electronic equipment in its specified range, causing electronic equipment to malfunction. This makes the Electro-Magnetic Pulse one of the most devastating weapon in the world causing huge damage to any devices. We include all the bases of Electro-Magnetic Pulse generation and its possible causes & effects on the nearby electronic components within its specified range capability. We introduced a novel system to destroy this kind of hidden cameras in the dressing rooms. In our project, using an application of we can eradicate the issues of the hidden camera for the women and children falling victims. The EMP will devastate any devices which it encounters on its range. We can also use this technology for military defense purpose in order to deactivate the hidden nuclear weapons.

Relativistic air-plasma far-infrared radiation effects by ultrashort laser pulses in air

Interactions of ultrashort laser pulses with gases have a wide variety of applications including lighting control, electromagnetic radiation and remote sensing. Considering the radiation effects, the ionization process, plasma formation and the current produced due to the formed plasmas, are the important fundamental processes. Here, a 2D relativistic fluid model is presented in which the interaction of an ultrashort laser pulse with air, leading to the electromagnetic pulse generation, is investigated. As the model is relativistic, it is appropriate for the investigation of the air-plasma radiation effects at high intensities. The results show that the intense laser-air interaction is suitable for the intense broadband far-infrared pulse generation due to the fact that the wave amplitude increases with the laser intensity. Moreover, for the laser intensities above 1020 W/m2, the laser pulse magnetic field gives rise to a strong axial electron current and a consequent axial wave component, which has to be accounted for in the proposed physical models. In addition, the Fourier transform analysis reveals that the radiated pulse is broadband and its frequency spectrum is not affected by the laser intensity.

Numerical modeling of short electromagnetic pulse propagation in nonequilibrium and nonstationary plasma media

A general approach is developed for the numerical study of short electromagnetic pulse propagation in nonstationary and nonequilibrium plasma or dielectric media. It is based on the numerical integration of the second order wave equation. Special attention is paid to the response function of nonstationary and nonequilibrium plasma to the external electromagnetic pulses of different frequency bands which are of an arbitrary duration. The details of numerical code realization are discussed. The possibility of using the developed approach to study the radio communication blackout problem is demonstrated.

Arecibo ALFA Array Observations in Search of Lunar Meteoroid-Strike EMPs

We present the preliminary results of a search for transient Electromagnetic Pulses (EMP) associated with the impact of meteoroids on the lunar surface as observed with the Arecibo Observatory ALFA (Arecibo L-band Feed Array) system. The ALFA system is a cluster of seven, dual-linear polarization feeds/beams arranged in a hexagonal manner and operated in the protected L-band region centered at 1.41 GHz. We analyzed 8 TB of data totaling nearly 5.5 h of on- and off-moon observations made in February 2016. We demonstrate the observing strategy and time–frequency methods for the detection and removal of the local-radar transient interference signals while identifying potential EMPs. Local out of band radar interference signals are observed as intermodulation artifacts in the protected L-band. Seven transient wideband EMP events with time scales of less than 10 μs have been detected following the extensive vetting process we describe. Assuming that these EMP-like events originate from gram-sized meteoroid strikes and using very approximate hypervelocity impact, plasma production theory, and EMP generation theory, we estimate the progenitor impact meteoroid kinetic energy to be approximately 1.8 × 107 J. Assuming that the observed EMPs are the result of 10 g meteoroid impacts, the resultant meteoroid flux is 3 × 10−7 km−2 h−1 based solely on lunar surface area observed and net observing period. Implications of the observed transient EMP events, measured lunar noise temperature and the comparison with energy estimates derived from the existing lunar impact optical observations are also discussed.

Group velocity mismatch at ultrashort electromagnetic pulse propagation in nonlinear metamaterials

Abstract The parametric interaction of optical wave pulses in metamaterials is considered in the first approximation of the theory of dispersion. The interaction between the quasi-monochromatic pump wave and the wave pulse at the total frequency with quadratic phase modulation is assumed. The results of calculation of the shape of the spectrum of an excited signal wave at a difference frequency are presented for low frequency pumping. It is shown that the effects of group mismatch in metamaterials lead to a narrowing of the spectrum of the excited wave. With an increase in the modulation degree of a weak exciting wave, the spectrum of the excited wave broadens.

Measurement of the electric field strength generated in the experimental chamber by 10 TW femtosecond laser pulse interaction with a solid target

Results are reported on a direct measurement of the electric field of a strong electromagnetic pulse generated through laser interaction with a thick solid target inside an experimental chamber of a 10 TW femtosecond laser. Two Prodyn FD5C conductive D-dot probes were used to demonstrate that the signal-to-noise ratio in this arrangement is 10:1 and that probes are sensitive to the component of the electric field parallel to their axis. Maximum value of the electric field on the order of 18 kV/m was obtained for a 50 fs laser pulse with 270 mJ energy on target. To ascertain a correct estimate of the recorded electric fields a comparative study was performed in an anechoic chamber with two other D-dot probes, involving electromagnetic pulses emitted by a tube antenna and the high-power broadband electromagnetic pulse generator. Some frequency dependence in the FD5C equivalent area was found below 1 GHz.

Electron Beam Driven Generation of Frequency-Tunable Isolated Relativistic Subcycle Pulses.

We propose a novel scheme for frequency-tunable subcycle electromagnetic pulse generation. To this end a pump electron beam is injected into an electromagnetic seed pulse as the latter is reflected by a mirror. The electron beam is shown to be able to amplify the field of the seed pulse while upshifting its central frequency and reducing its number of cycles. We demonstrate the amplification by means of 1D and 2D particle-in-cell simulations. In order to explain and optimize the process, a model based on fluid theory is proposed. We estimate that using currently available electron beams and terahertz pulse sources, our scheme is able to produce millijoule-strong midinfrared subcycle pulses.

Terahertz Solitons in Condensed Media

Theoretical approaches to the formation and propagation of soliton-like broadband electromagnetic and acoustic pulses with terahertz frequencies in condensed media are reviewed. Solitons of different types are analyzed and controlling their parameters by modifying the nonlinear medium is discussed. Nonlinear molecular excitations in biopolymers whose frequencies fall into the terahertz range are considered, and their interactions with external fields of resonant frequencies are discussed.

Advanced Dielectrics and Related Devices

SiO2 and related dielectrics are basic constituents of many optical and electronic devices with applications in frontier optoelectronics as well as in many radiation and harsh environments. The ongoing activity of researchers ranges from fundamentals of the electron processes, including defects formation and radiation-matter interaction; to growth mechanisms, spanning from bulk to fibers, nanostructures and composites; to characterization techniques and to modeling, simulation, and devices. This issue contains 24 articles selected from the contributions to the International Symposium SiO2, Advanced Dielectrics and Related Devices, held on June 11–13, 2018 in Bari, Italy. It was the XII edition of a symposium with French-Italian organizing committees which brought together more than 60 researchers from all around the world. The collected contributions cover the different research activities of the symposium community highlighting the recent advancements and perspectives together with the forefront topics. The four feature articles span from SiO2 optical fibers where radiation, temperature and doping are shown to be critical for applications, to graphene transferred to SiO2, evidencing the relevant role of the dielectric substrate in affecting the electronic properties of the 2D material. The other frontier topics concern attractive applications of photonic and plasmonic integrated cavities in the field of biosensing and trapping of biological matter at the nanoscale as well as novel computational models for simulating electromagnetic pulse propagation into dielectrics enabling the prediction in applicative tasks. The original papers can be grouped in hot topics of defects characterization and formation in crystalline and amorphous SiO2 with reference also to F, Bi, Al, P, Gd and other dopants of recent and avant-garde interest for applications, considering both experimental and simulative studies. In addition, many optical devices including sensors, optical fibers and waveguides have been reported evaluating both their stability and performances. Finally, nanostructures, ceramics and composites system based on SiO2 have been deepened with perspective to applications in emerging fields as solar energy, healthcare and environment. We kindly acknowledge all the authors and the reviewers for their contribution and the Journal Physica Status Solidi (a) for acceptance to publish this special issue. The editor's continuous support during all the publication steps has been indispensable for the final goal. The SiO2 Symposium is one of the best forums to meet and exchange ideas in the physics and chemistry of SiO2 and novel dielectrics. Finally, we would like to dedicate this issue to Roberto Boscaino, passed away this year. On behalf of the scientific community we express our deepest respect for him: for both what has he done himself directly in Physics and, in particular, for the enormous and successful work done in developing his research group, teaching, supporting and encouraging his collaborators. Together with Italian and French colleagues, Roberto Boscaino has fully promoted the SiO2 Symposium and created a strong international momentum in SiO2 studies. Organizing committee Luciano Mescia (Chair) Marco Cannas (Chair) Simonpietro Agnello Franco Mario Gelardi

The History and Use of Electromagnetic Weapons

This thesis is about the origin and development of electromagnetic weapons used in policing and military tasks as a non-lethal tool. The electromagnetic weapon was taken into consideration as a military or police means of antipersonnel engagement in the late 1970s. In the 1980s the USA conducted some defense programs towards development of lethal high energy laser weapons, to shoot down ballistic missiles and high-power microwave weapons designed to destroy electronic equipment. This technology was adapted by US Joint Non-Lethal Weapons Directorate (JNLWD) to construct new or adapted non-lethal delivery systems, which could be used in military operations. Until late 1990s several types of electromagnetic weapons were created and taken into account for practical use. The most important were: Active Denial System and electromagnetic pulse generators devices, for example E-bomb, which was probably used against Iraq in 2003 war.

Time detector design for Time-of-Flight Elastic Recoil Detection Analysis (ToF-E ERDA)

Time-of-flight-energy elastic recoil detection analysis (ToF-E ERDA) is a uniquely powerful thin-film analytical technique because it can be used to measure simultaneously the depth distributions of all elements in a thin-film sample. The basic design of the time detectors which are generally based on the electron mirror has not changed significantly over 25 years or so. A classic electron optical study has been made to elucidate the factors that limit the time resolution of electron mirror time pick off detectors and how they are interrelated. Degradation of the time resolution is mainly associated with the electron divergence from an ideal straight trajectory and variations in the propagation of electromagnetic pulses over the anode surface. A set of equations that can be used to optimise time detector design are presented along with a new configuration that has an expected time resolution of 40 ps fwhm and overcomes most of the drawbacks of the conventional configuration.

Effect of target size on electromagnetic pulses generation from laser radiation with targets

The cylindrical cavity is needed to realize inertial confinement fusion (ICF) via an indirect driving mode, which will generate abundant plasmas and hot electrons when the laser irradiates cavity at the ShenGuang-III laser facility, leading to radiation of intensive electromagnetic pulses (EMP) inside and outside the laser chamber. It is thus significant to reveal the relationship between the EMP’s intensity and distribution with laser parameters since it can be helpful to understand ICF and benefits shielding design to protect various diagnostics. The EMP intensity decreased with the size of the cylindrical cavity chamber, which was also confirmed by the simulating results obtained by developing a cylindrical model with different sizes.