Propagation Of Electromagnetic Pulses Research Articles

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.

Operating Member of Shock Machines Based on the Non-axial Slider-crank Mechanism with a Disjointed Slider

To perform various technological operations to process and destruct materials, power pulses of high amplitude and very short duration are necessary. Special devices, which can be hydraulic, pneumatic, electromagnetic or mechanical pulse generators, generate such shock pulses. Mechanical generators of power pulses can be based on the various mechanisms, many of which are among the mechanisms of a variable structure.The Machinery Researching Institute of National Academy of Sciences of Kyrgyz Republic has offered to use the crank-slider mechanism of a variable structure with a disjointed slider in the shock machines. The operation aspect of this mechanism is that at the beginning of the working course a lead (drive dog) and a hammer block, which form the slider, make a joint movement, are separated when the lead movement slows down, and then upon the shock of the hammer block to the tool and the mechanism being under idle operation these two parts again make a joint movement.The shortcoming of this mechanism is that its coefficient of the changing average speed of the slider is equal to unit. But as to the shock machine, it is desirable for this coefficient to be higher than one. In this case the average speed of the slider at the working course will be higher than when idling, and the hammer block can have the higher speed. Also it should be noted that when idling there are more favorable conditions to fix the hammer block, which has made a rebound after the shock to the tool, with a lead at great values of the coefficient of the changing average speed of the slider.The coefficient of the changing average speed of the slider can be increased through the crank support shift in direction, perpendicular to the trajectories of the slider movement, by converting an axial mechanism into the non-axial one. Based on the specified values of frequency and energy of blow and also conditions for ensuring the working capacity and compactness of the shock machine, the paper makes synthesis of key parameters of the operating member of the non-axial slider-crank mechanism with the disjointed slider.

Simulation of electromagnetic pulses generated by escaped electrons in a high-power laser chamber

Intensive electromagnetic pulses (EMPs) can be generated when a high-power laser strikes a target. The transient electromagnetic field can have an intensity of up to several hundred kV m−1 with a broad frequency of up to several gigahertz, which may affect diagnostics and interfere with, or even damage, electronic equipment. In this paper, the process in which hot electrons produced by the laser−target interaction radiate EMPs is studied and simulated. The physical process is divided into three stages which are: the production of hot electrons; the escape of hot electrons; and the generation of EMPs. Instead of using a general finite difference time domain (FDTD) method to solve the Maxwell equations, a particle-in-cell method together with a time-biased FDTD method is applied in EMP simulation to restrain high-frequency noise. The results show that EMPs are stronger with higher laser intensity and larger target size.

Electron Dynamics and Characteristics of Attosecond Electromagnetic Emissions in Relativistic Laser-Plasma Interactions**Supported by the National Natural Science Foundation of China under Grant No 11674146, and the National Basic Research Program of China under Grant No 2013CBA01500.

Generation of attosecond electromagnetic (EM) pulses and the associated electron dynamics are studied using particle-in-cell simulations of relativistic laser pulses interacting with over-dense plasma foil targets. The interaction process is found to be so complicated even in the situation of utilizing driving laser pulses of only one cycle. Two electron bunches closely involved in the laser-driven wavebreaking process contribute to attosecond EM pulses through the coherent synchrotron emission process whose spectra are found to follow an exponential decay rule. Detailed investigations of electron dynamics indicate that the early part of the reflected EM emission is the high-harmonics produced through the relativistic oscillating mirror mechanism. High harmonics are also found to be generated through the Bremsstrahlung radiation by one electron bunch that participates in the wavebreaking process and decelerates when it experiences the local wavebreaking-generated high electrostatic field in the moving direction.

Symmetric split Hopkinson compression and tension tests using synchronized electromagnetic stress pulse generators

This work presents an original impact testing arrangement and its applications using two identical synchronized stress pulses to load symmetrically the specimen sandwiched between the two identical Hopkinson pressure bars. In order to obtain two synchronized stress pulses, two identical electromagnetic stress pulse generators connected to the same LC discharge circuit are used. This symmetric impact loading configuration might be easily interchanged into a compressive as well as a tensile version because of the versatility of the electromagnetic stress pulse generators.In order to validate this apparatus, two materials (copper alloy and aluminum alloy) are tested in compression and in tension using this new experimental setup. The measured forces and velocities at the pressure bar/specimen interfaces are indeed identical and simultaneous. The derived material properties of tested materials are compared with those of the traditional split Hopkinson bars and a good agreement is found.A new symmetric Double Cantilever Beam (DCB) test using this experimental device is also presented. It allows overcoming the difficulties of only one moving side in previous work, which avoids an induced mode II component in a DCB test supposed to be a pure mode I testing.

Modulation instability in two-dimensional waveguide arrays with alternating signs of refractive index

We consider the propagation of coupled forward and backward waves in two-dimensional arrays of alternating waveguides with positive and negative refractive indices. The array has a cross section in the form of a face-centered square lattice. The unit cell consists of three different waveguides with different optical properties. We obtain the condensate solutions for electromagnetic pulse propagation in such an array of waveguides. The base equations describing this model have solutions that correspond to the static and homogeneous intensity distribution on the waveguides. The stability of these solutions in both normal and anomalous dispersion regimes is also investigated using modulation instability analysis.