Pulsed Electromagnetic Radiation Research Articles

Characteristics of quasi-unipolar electromagnetic pulses formed in the interaction of high-power laser pulses with nanoscale targets

A new method is suggested for generating quasi-unipolar electromagnetic IR and terahertz pulses. The method is based on synchronous acceleration of electrons combined to a dense bunch with a charge of up to several tens nanocoulombs, which are forced out from a nanoscale target under an action of a high-power, sharp-leading edge laser pulse. The electromagnetic bunch moving in a field of laser radiation can generate high-power electromagnetic pulses with various spectral composition including terahertz and IR ranges. A physical mechanism underlying the formation of generated quasi-unipolar pulses of electromagnetic radiation is determined and numerically studied. The pulse characteristics are found by numerical simulation, such as amplitude and duration dependences on the angle between the pulse propagation direction and laser beam axis. It is established that in modern laser installations, the amplitudes of quasi-unipolar pulses may reach relativistic values. Reflection of a unipolar pulse from an ideally reflecting surface is numerically analysed. It is shown that the pulse retains its unipolar profile in this case.

Kinetics of Chemical Reactions under Exposure to Light near the First Ignition Limit of an Explosive Mixture

In this paper, we theoretically studied examined the effects of pulsed and continuous electromagnetic radiation on the generation and branching of chains in an explosive mixture near the first limit of ignition using the Semenov kinetic scheme. The effects of processing the inner surface of a quartz reactor in the interval between experiments with pulsed light of a xenon lamp on the intensity of the generation reaction under the first ignition limit of an explosive mixture were experimentally studied. Light irradiation energy (0.5 J, 200 pulses) was found to be insufficient for a noticeable effect on surface active centers and the generation reaction.

Uncertainty Quantification for the Transient Response of Human Equivalent Antenna Using the Stochastic Collocation Approach

The paper deals with the uncertainty quantification of the transient axial current induced along the human body exposed to electromagnetic pulse radiation. The body is modeled as a straight wire antenna whose length and radius exhibit random nature. The uncertainty is propagated to the output transient current by means of the stochastic collocation method. The stochastic approach is entirely nonintrusive and serves as a wrapper around the deterministic code. The numerical deterministic model is based on the time domain Hallen integral equation solved by means of the Galerkin-Bubnov indirect boundary element method (GB-IBEM). The stochastic moments, i.e., the mean and the variance of the transient current, are calculated. Confidence margins are obtained for the whole duration of the transient response as well as for the maximal current value. The presented approach enables the estimation of the probability for the induced current to exceed the basic restrictions prescribed by regulatory bodies. The sensitivity analysis of the input parameters indicates to which extent the variation of the input parameter set influences the output values which is particularly interesting for the design of the human equivalent antenna.

THE IMPACT OF BROADBAND ELECTROMAGNETIC PULSES ON THE COGNITIVE REACTIONS OF WHITE MICE

There were executed studies to assess the impact of broadband pulsed electromagnetic radiation on the central nervous system of white mice in test “open field”, “T-maze”, “Forced swimming”. The results of the study proved the influence of pulsed electromagnetic radiation on cognitive function. Experimental studies were performed in a shielded equipped semi-anechoic chambers with the remote control of the work of the simulator of broadband pulse EMT. At the end of the performed studies it was revealed that when exposed to broadband pulsed electromagnetic radiation into three groups of animals (exposure of 15, 30, 60 minutes) only in the group with exposure for 15 minutes there were no detected changes in behavioral responses. In the other two groups there were shown statistically significant changes in indices of the horizontal and vertical locomotor activity. The results confirm the possibility of separation between the processes of inhibition and excitation under the influence of EMF of low intensity (non-thermal) on biological objects.

On Acceleration of a Relativistic Particle by a Radiation Pulse

Concerning direct acceleration of charges by pulses of electromagnetic (laser) radiation with arbitrary shapes, we have found a relationship between the components of the mechanical momentum of a relativistic (but not ultrarelativistic) particle. In a wide range of conditions, the energy transferred by the radiation to a particle to be accelerated is determined by the electric area of the laser pulse, i.e., by the integral of the electric field strength over the pulse time. This indicates that it is promising to develop schemes for generation of quasi-unipolar radiation laser pulses, in which the strength of the dominant component of the electric field does not change its sign during the main pulse duration.

Об ускорении релятивистской частицы импульсом излучения

AbstractConcerning direct acceleration of charges by pulses of electromagnetic (laser) radiation with arbitrary shapes, we have found a relationship between the components of the mechanical momentum of a relativistic (but not ultrarelativistic) particle. In a wide range of conditions, the energy transferred by the radiation to a particle to be accelerated is determined by the electric area of the laser pulse, i.e., by the integral of the electric field strength over the pulse time. This indicates that it is promising to develop schemes for generation of quasi-unipolar radiation laser pulses, in which the strength of the dominant component of the electric field does not change its sign during the main pulse duration.

Magnetic-field creation by solar-mass neutrino jets

Parity violation and its effects for neutrinos in astrophysical contexts have been considered earlier in pioneering papers of Hawking and Vilenkin. But because even the largest magnetic moments predicted by physics beyond the Standard Model are some twelve orders of magnitude smaller than the Bohr magneton, their implications for magnetic-field generation and neutrino oscillations are generally considered insignificant. Here we show that since in astrophysical scenarios a huge number of neutrinos may be emitted, the smallness of the magnetic moment, when coupled with parity violation, is compensated by the sheer number of neutrinos. The merger of neutron stars would leave behind a short pulse of electromagnetic synchrotron radiation even if the neutrino jet in the merger points away from the neutrino detectors. We show that the magnetic field can be as large as 106 Gauss and comment on the possibility of direct detection. Observation of such a pulse would lend strong support for neutrino magnetic moments and resolve the missing neutrino problem in neutron star mergers.

Experiment research on electromagnetic pulse effects of typical nuclear security system

High-altitude electromagnetic pulse(HEMP) is a kind of transient electromagnetic wave which can be coupled into various electronic and electrical equipments through field lines or holes. To ensure that the security system of key departments can work normally under the electromagnetic pulse environment, it is necessary to carry out the electromagnetic pulse effect test against the security system, and analyze the weak link and survival ability of this kind of system under the electromagnetic pulse environment. According to the topology of nuclear security system, the electromagnetic pulse radiation test and pulse current injection test platform are set up, and the threshold and effect phenomena of the key components of the nuclear security system are obtained through the test. Furthermore, the failure mechanism of key components is analyzed based on the circuit principle of each component, and the weak link of typical nuclear security system is summarized, which provide data support for the protection and reinforcement design of the follow-up security system.

强电磁脉冲辐照屏蔽舱结构电子系统的效应仿真

强电磁脉冲辐照屏蔽舱结构电子系统的效应仿真

Out-of-equilibrium electron dynamics of silver driven by ultrafast electromagnetic fields - a novel hydrodynamical approach.

We investigate the ultrafast nonlinear response of silver upon excitation by infrared electromagnetic radiation pulses with a duration of a few femtoseconds. By adopting the Landau weak coupling approach to account for electron-electron and electron-phonon collisions, we solve the Boltzmann equation through the method of moments obtaining a novel set of hydrodynamical equations describing the ultrafast nonlinear dynamics of electrons in silver. While the novel hydrodynamical model that was obtained reduces to the Drude model for small intensities of the driving field, it predicts that absorption saturates for large but experimentally attainable peak intensities of the order of GW cm-2. Our results are important for absorption mitigation in plasmonic devices, with potential impact for low-loss plasmonic waveguides and interconnects.

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.

New ultra high-speed all-optical coherent D-trigger

We study the interaction of two counterpropagating unipolar video pulses of electromagnetic radiation in a dense resonant two-level medium. The pulse durations are less than one oscillation period of an atomic transition. We show that a polariton cluster (i.e. the compact long-living strongly coupled state of electromagnetic field and matter polarisation) is created, when two unipolar video pulses collide in a resonant medium of the frequency ωo (the pulses correspond to self-induced transparency solitons of the same amplitudes and opposite polarities).We studied for the first time multiple recording and erasing of a polariton cluster in a thin layer of a resonant medium (quantum dots) placed on the mirror surface. We showed that dynamics of the medium population difference N(x,t) is analogous to the operation of a D-trigger of the pulse rate 60 000 GHz and higher. We found such a method of the polariton cluster recording and erasing that excludes the accumulation of erasing errors. Therefore, the total duration of the optical D-trigger operation time can strongly exceed the phase relaxation time T2.

Electromagnetic Radiation Characteristics of Series DC Arc Fault and Its Determining Factors

A dc arc fault can be a serious threat to the safe operation of a low-voltage dc system. Typically, a fair amount of electromagnetic radiation (EMR) accompanies the arcing process. To investigate the characteristics of EMR of the series dc arc fault, a fourth-order Hilbert fractal antenna is used to detect the EMR signals generated by the dc arc. The factors influencing the characteristics of EMR including electrode material, diameter, current, and pressure are considered. The amplitudes of the EMR pulses at the arc initiation moment are measured, and fast Fourier transform is used to analyze the characteristics of the frequency spectrums. The test results indicate that the amplitudes of the EMR pulses generated by stainless steel electrodes are higher than those generated by brass, copper, and aluminum electrodes. Furthermore, the trends of the amplitudes of the EMR pulses with increasing current are different for electrodes with different diameters. Finally, it is observed that the influence of the pressure is different for different electrode materials. The characteristic frequency band of the EMR pulses of the dc arcs generated under various test conditions is in a certain range (36–41 MHz), which can be used as a detecting characteristic parameter for the series dc arc.

The effect of 2.45 GHz non-ionizing radiation on the structure and ultrastructure of the testis in juvenile rats.

Nowadays, mobile devices that emit non-ionizing electromagnetic radiation (EMR) are predominantly used by juveniles and pubescents. The aim of the present study was to evaluate the effect of whole body pulsed EMR on the juvenile Wistar albino rat testis at a frequency of 2.45 GHz and mean power density of 2.8 mW/cm². The investigated animals (n=24) were divided into two control and two EMR groups (5 and 6 week old rats; 6 rats per group). Both EMR groups were irradiated continually for 3 weeks (2h/day) from postnatal days 14 and 21, respectively. EMR caused an irregular shape of seminiferous tubules with desquamated immature germ cells in the lumen, a large number of empty spaces along the seminiferous epithelium and dilated and congested blood vessels in the interstitial tissue of the testis. The cytoplasm of Sertoli cells showed strong vacuolization and damaged organelles, with the cytoplasm full of different heterophagic and lipid vacuoles or the cytoplasm of spermatocytes with swollen mitochondria in both irradiated groups. A significant increase in the total tubular area of seminiferous tubules was observed in both EMR groups compared with controls (P<0.001). A significant increase in the TUNEL-positive apoptotic nuclei (P<0.01) was accompanied by a significant rise in both Cu-Zn-SOD (P<0.01) and Mn-SOD (P<0.001) positive cells in the 6 week old experimental rats compared to control animals. Our results confirmed a harmful effect of non-ionizing radiation on the structure and ultrastructure of the juvenile rat testis.

Study on SAR Distribution of Human Body on the Vehicle Platform Using a Modified FDTD Method

This paper is devoted to characterizing the specific absorption rate (SAR) distribution of a human body model in a vehicle-based shelter in the presence of high-power intentional electromagnetic pulse (IEMP) radiation using a modified finite-difference time-domain (FDTD) method. The proposed method combines the FDTD(2, 4) method along with dielectric conformal techniques, where the updating equations of FDTD(2, 4) method are modified by introducing an effective dielectric constant and a new conductivity derived by area average of different dielectric regions including coating layer in nine spatial discrete cells. Numerical results show that our method even with coarse meshes has good agreements and efficiency comparing with the traditional FDTD method and CST simulation tool. Furthermore, the proposed method is applied to predict the SAR distribution of human body in a vehicle-based metallic shelter, where the peak SAR and average SAR are captured and compared in the presence of an IEMP with different polarizations and incident angles.

EXTRANEOUS ELECTROMAGNETIC RADIATION IMPACT ON WAVEGUIDE CHARACTERISTICS OF A SEMICONDUCTOR SUPERLATTICE

The subject matter is the mechanisms of emergence of instabilities in natural oscillations of semiconductor supertattices caused by their interaction with charged particle flows of extraneous electromagnetic radiation. The aim is calculating ratios to determine a degree of deviation of operating characteristics of semiconductor components from the norm, depending on the parameters of extraneous pulsed electromagnetic radiation. The objective is to model how currents that are induced with extraneous EMR interact with electrostatic oscillations of a semiconductor supertattice, using an implementation of (Cherenkov) resonance interaction of moving charges with electromagnetic oscillations under conditions where the phase velocity of the wave and the velocity of the charged particle are the same. The methods used: analytical methods for solving Maxwell's equations and medium equations in a framework of hydrodynamic approach. The following results are obtained. We have studied semiconductor components of electronic equipment (supertattices) being exposed to strong pulsed electromagnetic fields. The study was focused on the nature of changes in the working capacity of the components. We show that the effect of pulsed electromagnetic radiation is accompanied by an emergence of currents in the conductive hardware elements and an emergence of internal fields within them. One kind of reversible failures of semiconductor hardware elements is determined, based on interaction of extraneous radiation induced currents with the intrinsic fields of the supertattices of the hardware components. Similar failures occur under conditions of Cerenkov radiation (when the current is parallel to the structure boundary). It is shown that such interaction leads to energy losses in the induced currents spent to excitation of natural oscillations of the supertattice, i.e. to emergence of an oscillation generation mode that is characterized with a change in the volt-ampere characteristics of the hardware. Conclusion. The results obtained in this work can be used to evaluate the efficiency of active radio electronic devices (amplifiers, generators and converters of electromagnetic oscillations in the millimeter and sub-millimeter ranges) being exposed to extraneous pulsed electromagnetic fields. The comparative analysis of quantitative evaluations of reversible failures of semiconductor devices in dependence on the spatial configuration of the acting field (induced current parallel to the structure boundary) allows solving problems in optimizing the degree of distortion of the performance characteristics of these devices.

Study on characteristics of EMR signals induced from fracture of rock samples and their application in rockburst prediction in copper mine

A rockburst is a dynamic disaster that occurs during underground excavation or mining which has been a serious threat to safety. Rockburst prediction and control are as important as any other underground engineering in deep mines. For this paper, we tested electromagnetic radiation (EMR) signals generated during the deformation and fracture of rock samples from a copper mine under uniaxial compression, tension, and cycle-loading experiments, analyzed the changes in the EMR intensity, pulse number, and frequency corresponding to the loading, and a high correlation between these EMR parameters and the applied loading was observed. EMR apparently reflects the deformation and fracture status to the loaded rock. Based on this experimental work, we invented the KBD5-type EMR monitor and used it to test EMR signals generated in the rock surrounding the Hongtoushan copper mine. From the test results, it is determined the responding characteristics of EMR signals generated by changes in mine-generated stresses and stress concentrations and it is proposed that this EMR monitoring method can be used to provide early warning for rockbursts.

Design and Evaluation of a Sensitive, Low Cost and Portable Millimeter Wave Survey Meter

We developed a small, hand-held, portable, low cost, millimeter wave (mmW) meter to detect and display the levels of emissions from L3 ProVision security scanners used in hundreds of airports for detection of contraband and weapons. The meter is intended to measure radiation emissions from this particular scanner and enable the user to enable periodic quality assurance measurements and to see if undesirably high levels were to occur. The non-engineering staff of the Transportation Security Administration (TSA) can use this meter to demonstrate safety of these scanners to passengers using this simple handheld instrument certified by the US Food Drug administration. This meter can assess human exposure levels during periodic quality assurance inspections, in a region where a person is being scanned, and demonstrate the lack of possible interference with body worn medical devices. It has receiving, signal processing, output display, and user control subsystems, and displays graphical and numerical information. The meter detects low level, pulses of mmW electromagnetic radiation (20 - 30 GHz with levels of 0.02 V/m to 0.15 V/m). It displays a single burst of five or more 10 μsec pulses. It detects levels as low as several thousand times below the maximum permissible levels prescribed by international human exposure safety standards. This compact system replaces the bulky and costly collection of large and costly instruments needed to perform the same measurements.

Attosecond nanotechnology: from subatomic electrostatic strings entangling electron pairs to supra-atomic quantum nanoelectromechanical systems energy storage in materials

This paper is concerned with a physical model and computer simulation describing joint processes of attosecond bi-electronics and femtosecond electronics at the supra-atomic level of materials. It has been proved that an external attosecond pulse of electromagnetic radiation excites an electrostatic χ-string of the gauge electromagnetic field in materials, which entangles a subatomic electron pair (ē~χ~ē). This string is a result of spontaneous breaking of the gauge electronic field symmetry of the condensed state. The quantum coherence length of attosecond propagation in a subatomic entangled electron pair varies from 0.1 nm to 10 nm and determines a spatial supra-atomic level in non-equilibrium materials. Attosecond processes of bi-electronics and femtosecond processes of standard electronics take place at the nanometre scale of materials from one to several thousand atoms. General approaches of thermo-field dynamics and quantum field chemistry of the condensed state describe joint parallel energy dissipation processes in the Fermi gas of electrons and the Bose gas of bi-electrons. Boundaries of bi-electron supercapacitor electrostatic χ-strings confine a part of nuclei and an electron Fermi gas inside their compact spatial basin. They create quantum nanoelectromechanical system energy storage. This paper presents main stages of the genesis of quantum nanoelectromechanical system energy storage using attosecond pulses of ultra-violet and soft X-ray radiation. The paper also provides computer modelling of the quantum nanoelectromechanical system with 500 atomic cuboids in the face centred cubic (FCC) crystal lattice of the palladium group metals at the temperature of 77 K. It is shown that these cuboids stable accumulate energy about 1 keV that corresponds with quanta of soft X-ray radiation.

Измерительный комплекс для определения устойчивости радиоэлектронной аппаратуры к помехам импульсного электромагнитного излучения

Измерительный комплекс для определения устойчивости радиоэлектронной аппаратуры к помехам импульсного электромагнитного излучения