Development of Poynting vector direction method for electromagnetic pulses in the earth

Due to the increase in the threat of attacks with high-power electromagnetic (EM) pulses, there is great interest in metallic enclosures with high shielding effectiveness (SE). Necessary technological apertures in these enclosures reduce their effectiveness. Understanding the penetration and internal propagation of the high-power EM pulses into an apertured enclosure is fundamental to assessing the EM SE of the enclosure. In the present paper, results of the numerical simulations of development of the EM field in a shielding enclosure with aperture after the interference of a subnanosecond high-power EM plane wave pulse of the parallel polarization (having the duration of 0.3558 ns and the amplitudes of the electric and magnetic fields of 106 V/m and 2.6 × 103 A/m, respectively) are presented. The results obtained include 3D and 2D images , vector maps of the EM field developed inside the enclosure, and time-varying distributions of the electric charges formed on the inner walls of the enclosure. They revealed the mechanism of formation of the EM field inside the enclosure caused by the subnanosecond high-power parallelly polarized EM pulse. The EM field formed in the enclosure with aperture has the form of the electric and magnetic field interference structures. They are a superposition of the incident EM pulse field, which entered the enclosure through the aperture in the way described by the geometrical (ray) optics, the electric field generated by the electric charges formed on the aperture edges and inner sides of the walls of the enclosure, and the magnetic field generated by the surface current formed on the aperture edges and on the inner walls of the enclosure. The amplitudes of the electric and magnetic fields of the strongest EM interference structures decrease non-monotonically to about 0.7 × 105 V/m and 200 A/m at t = 5 ns. We found that the points in the enclosure are subjected to the disturbance of a long series of subnanosecond EM pulses, which we have called internal EM pulses. The amplitudes of these internal pulses are lower than those of the incident EM pulse. Nevertheless, they can pose a severe EM hazard inside the enclosure due to their large number (about 900 internal pulses in 30 ns). This means a fundamental change in the character of the EM disturbance caused by the subnanosecond pulse when the enclosure with aperture is used as a shield.

This paper considers the use of electromagnetic pulses (EMP) to inject transient faults into the calculations of a hardware and a software AES. A pulse generator and a 500 um-diameter magnetic coil were used to inject the localized EMP disturbances without any physical contact with the target. EMP injections were performed against a software AES running on a CPU, and a hardware AES (with and without countermeasure) embedded in a FPGA. The purpose of this work was twofold: (a) reporting actual faults injection induced by EMPs in our targets and describing their main properties, (b) explaining the coupling mechanism between the antenna used to produce the EMP and the targeted circuit, which causes the faults. The obtained results revealed a localized effect of the EMP since the injected faults were found dependent on the spatial position of the antenna on top of the circuit's surface. The assumption that EMP faults are related to the violation of the target's timing constraints was also studied and ascertained thanks to the use of a countermeasure based on monitoring such timing violations.


 Inside the plasma, when an intense rippled electromagnetic radiation pulse experiences self-focusing, one need to taking account of radial expansion in view of charge displacement due to ponderomotive force on electron and variation in the mass of oscillating electron under the influence of relativistic effect due to electromagnetic field. The extraordinary-mode (E-mode) propagation in a magnetoactive plasma, with stationary magnetic field, which is analogous to the wavering magnetic field of the electromagnetic radiation pulse, is the key feature for the self-guided propagation of rippling electromagnetic radiation pulse in magnetoactive plasma. If the condition for ultra-fast volume ionization is achieved, the radiation pulse itself can generate such a stationary magnetic field. It is demonstrated that external magnetic field affects the channels, causing them to bend. These effects cast new light on the phenomena of self-focusing of rippled electromagnetic radiation pulse. They raise the possibility of combining energy from several channels into one. It is found that the magnetic field strongly influences the plasma dynamic behavior and overall propagation of rippled electromagnetic radiation pulse.
 Keywords: Self-focusing, Self-guidance, Magnetized-plasma, Beam-propagation, Nonlinearity

AIM: The present paper investigated the effects of Electromagnetic pulses(EMP) on the male procreative system to establish personnel protection guidelines for the new type of electromagnetic radiation. MATERIALS AND RESULTS: Rats were used in this study, and EMP irradiation parameter: 100Kv/m field intensity, 3×106 and 4×106 pulses respectively. SD male rats were sacrificed at 6h, 12h, 24h and 48h after 4×106 pulses irradiation, and the testis were prepared for transmission electron microscopy (TEM). The contents of follicle-stimulating hormone (FSH), luteinizing hormone (LH) and testosterone (T) in the serum were examined using radioimmunoassay after different times exposed to EMP. The activity of total superoxide dismutase(T-SOD) and manganese superoxide dismutase(MnSOD) were determined according to xanthine oxygenation method. Meanwhile the density of maleic dialdehyde (MDA) was determined by thibabituric acid method. By semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), MnSOD and copper/zinc SOD (CuZnSOD) mRNA in the rat testis have been observed at different time after irradiation. The protein of NFκBp65 and IκBα in rat testis was assayed by western blotting. Under TEM, the rat testis was damaged at different time after irradiation, the damage was more serious at 24h than the other times and it wasn’t recovered until 48h after irradiation; After 3×106 or 4×106 pulses, FSH in the serum didn’t change obviously, LH and T in the serum of the radiation groups were changed fluctuatedly compared with that of parallel control respectively; the activity of T-SOD and MnSOD in rat testis decreased at 24h and the contents of MDA increased at 6h after irradiation, MnSOD mRNA expression decreased in rat testis at 24h after exposure, and CuZnSOD mRNA expression didn’t change; the protein of NFκBp65 and IκBα in rat testis didn’t change obviously after irradiation. CONCLUSION: The morphology was damaged and the function and metabolism of procreative system were altered on the rats after irradiation. EMP induced indiscriminate hormone secretion and excessive free radicals and over expression of some genes in the male procreative tissue played some roles directly or indirectly for the bioeffects.

The dynamics of time evolution of quantum oscillator excitation by electromagnetic pulses is investigated theoretically for an arbitrary field amplitude in a pulse. We consider a harmonic oscillator without damping and excitation between stationary states. The general formula for the excitation of quantum states as a function of time is derived in terms of instantaneous energy of an associated classical oscillator in the field of an electromagnetic pulse. The derived expression is used in detailed analysis of the time dependence of the quantum oscillator excitation probability beyond the range of perturbation theory for various pulse parameters including total excitation from the ground state, excitation from excited states, and excitation spectra.

Over the past 100 years a variety of definitions have been introduced in order to describe the velocity of an electromagnetic pulse as it travels through a dispersive material. Although these velocity measures provide comparable results in those frequency regions of the material dispersion where the loss is small, they disagree wherever the material loss is large. In fact, some definitions of the pulse velocity yield nonphysical results (superluminal or negative velocities), while others apply only to certain pulse characteristics. In 1970, Smith1 addressed these issues while proposing a new definition for the velocity of an electromagnetic pulse which he called the centrovelocity. This centrovelocity is defined by the quantity $$ \left| {\nabla \left( {\int_{ - \infty }^\infty {tE^2 (r,t)dt} /\int_{ - \infty }^\infty {E^2 (r,t)dt} } \right)} \right|^{ - 1} $$ where E(r, t) is the real electric intensity vector. Notice that the ratio of the two integrals is analogous to a center of mass calculation since it tracks the temporal center of gravity of the intensity of the pulse. Recently, Peatross, Glasgow and Ware2 introduced a variant of Smith’s centrovelocity which tracks the temporal center of gravity of the real Poynting vector S(r, t) rather than that of the intensity of the pulse, where the Poynting vector is defined (in MKS units) as $$ S(r,t) = E(r,t) \times H(r,t). $$ (1) In this paper, the centrovelocity of a rectangular-modulated plane-wave electromagnetic pulse traveling in the positive z -direction in a Lorentz model3 dielectric material is calculated in two independent ways: the first uses an asymptotic approximation and the second uses a numerical code based on the fast Fourier transform algorithm. The results show that, in the asymptotic limit as z → ∞, the centrovelocity approaches the speed at which the Brillouin precursor travels through the causally dispersive material

Electromagnetic pulses with tilted pulse fronts are instrumental in enhancing the efficiency of many light-matter interaction processes, with prominent examples including terahertz generation by optical rectification, dielectric laser acceleration, ultrafast electron imaging and X-ray generation from free electron lasers. Here, we find closed-form expressions for tilted-pulse-front pulses that capture their exact propagation dynamics even in deeply nonparaxial and sub-single-cycle regimes. By studying the zero-bandwidth counterparts of these pulses, we further obtain classes of nondiffracting wavepackets whose phase fronts are tilted with respect to the direction of travel of the intensity peak. The intensity profile of these nonparaxial nondiffracting wavepackets move at a constant velocity that can be much greater than or much less than the speed of light, and can even travel backwards relative to the direction of phase front propagation.

The present work is devoted to the study of the dynamics of multi-photon processes in semiconductor heterostructures. A time-dependent description is important for understanding in detail the transient response of semiconductors excited by ultrashort optical pulses. In the first part of this thesis, we set up a phenomenological model based on rate equations, in order to investigate the possibility of measuring degenerate two-photon gain in a semiconductor microcavity. The amplification predicted by the model is fairly low ( 2%) and mainly limited by the intra-band relaxation of the carriers, which leads to rapid saturation. In the second part, we develop a general theory for the dynamics of multi-photon processes in semiconductors. It will give insight into complex effects related to the coherence between the bands, which are not included in usual absorption coefficients or susceptibilities. For this purpose, we derive effective multi-band Bloch equations that include resonant multi-photon processes induced by two linearly polarized electromagnetic pulses of frequency close to the band gap and close to the half of the band gap respectively. The benefit of the proposed approach is two-fold. First, the description of the dynamics is restricted to a reduced number of bands. However, the discarded bands are not neglected, but consistently taken into account in the higher order processes. Second, all quantities appearing in the effective multi-band Bloch equations vary on the same time scale, which makes the numerical integration much more efficient. The time-dependent polarization current, as well as some susceptibilities, are derived on a consistent level of approximation, and are discussed in detail. The propagation of the electromagnetic fields is neglected. Such a model is appropriate for the description of low-dimensional quantum confined systems (e.g. quantum wells or quantum wires) excited by two colinearly propagating pulses. It accounts for various linear and nonlinear optical processes, such as one- and two-photon absorption, second-harmonic generation, difference-frequency mixing, or coherent control of photocurrent. In this thesis, the general theory is applied to the study of three specific physical situations. First, we investigate the charge and spin current in a symmetric AlGaAs/GaAs quantum well, injected by interference between one- and two-photon inter-band transitions. We identify new coherent terms in the expression of the current, which contribute significantly to the terahertz emission. The effects of the Stark shifts and the inter-valence band two-photon transitions are also calculated and discussed. Second, we calculate the anisotropic two-photon absorption spectra of an AlGaAs/GaAs V-shaped quantum wire with realistic band structure. The Coulomb interaction is taken into account within the Hartree-Fock approximation. The various excitonic peaks are identified with respect to the involved subbands and to the symmetry properties. We also show that excitons that are dark for one-photon excitation may become bright for two-photon spectroscopy, when the light is polarized perpendicularly to the growth direction, but not along a symmetry axis of the wire. Finally, the last application focuses on the optical injection of current in the presence of excitonic effects. Concentrating on the same AlGaAs/GaAs V-shaped quantum wire, we show that the Coulomb interaction within the Hartree-Fock approximation induces terahertz oscillations in the injected charge current. The oscillation frequency corresponds to the energy spacing between the two lowest excitonic resonances, slightly below the band gap, excited respectively by the laser pulse with frequency close to the band gap, and the one with frequency close to the half of the band gap.

Generation of PP and PS angle gathers for elastic reverse time migration (ERTM) has important applications in velocity model updating and subsurface parameter inversion. The Poynting-vector-based method provides a cost-effective way to extract angle gathers from ERTM. However, the estimated propagation directions or angles based on Poynting vectors at or near zero points are unstable, and the reflection energy at these points is likely to be placed in an incorrect angle bin. This instability problem severely limits its use in the generation of high-quality angle gathers. To overcome this problem, we add the conventional Poynting vector with an ancillary one of the Hilbert transformed wavefield, a 90° phase-shifted version of the original wavefield. The Poynting vector of the Hilbert transformed wavefield points in the same propagation direction as the conventional Poynting vector, but they have different zero-point distributions. Adding them together allows us to obtain a stabilized Poynting vector which thoroughly eliminates the zero points within the wave propagation range, and thus we obtain a stable algorithm to extract high-quality angle gathers from ERTM. The Hilbert transformed wavefield already exists in the P/S and up/down wavefield decomposition procedure, which has become a necessary step for ERTM to separate overlapping wavefields at reflectors before the computation of Poynting vectors. Results from two synthetic numerical examples indicate the effectiveness of our method in generating high-quality angle gathers for ERTM.

Using the propagation of an intense electromagnetic pulse through a neutral plasma as a model, we demonstrate how one can obtain information about the nonlinear behavior of modulated waves. Assuming no resonant instabilities, the envelope can be shown to evolve over long time scales according to a vector form of the well-known cubic nonlinear Schroedinger (NLS) equation. In the weakly relativistic regime, three distinct nonlinear effects contribute terms cubic in the amplitude and thus can be of comparable magnitude: ponderomotive forces, relativistic corrections, and harmonic generation. Modulational stability of any given system is shown to depend on polarization, frequency, composition, and these dependences are given. In the special case of a cold positron-electron plasma, the model is strictly modulationally stable for both linear and circular polarization. However the presence of an ambient magnetic field can make a decisive difference. Now modulational instability can arise within a broad range of frequencies and values of Bq, m particular for a pure positron-electron plasma. For the case of intensely propagating (relativistic) EM plane plasma waves, we find that the circularly-polarized waves are modulationally unstable under a range of conditions. We use a unified approach which illustrates how the modulational instability changes as one moves from the weakly relativistic case to the fully relativistic case. And we are able to give the first self-consistent calculation of the modulational instability properties of a slowly-modulated, fully relativistic envelope. Modulated, intensely propagating EM waves couple (in general) to longitudinal motions via the ponderomotive force. The effect of longitudinal motions is comparable to that of relativistic nonlinearities. A correct and proper expansion procedure requires solution of all the field equations up to the appropriate order, including the longitudinal equations. In particular, in the extreme relativistic limit of either an electron-positron or ion-electron plasma, waves with frequencies below twice the relativistic plasma frequency ω p , where ω p 2 ≡ 4πe 2 n 0(1/(mγ 0) + 1/(MΓ0)), are unstable. Growth occurs on a very short timescale comparable to the time for a wave packet to move past a fixed point. (This timescale is much shorter than that for spreading of the wave packet due to linear dispersion.)

The present paper is devoted to a full quantum mechanical study of the cis-->trans isomerization of HONO. In contrast to our previous study [Richter et al., J. Chem. Phys. 120, 6072 (2004)], the dynamics is now performed in the presence of an external time-dependent field in order to be closer to experimental conditions. A six-dimensional dipole surface is computed. Using a previously developed potential energy surface [Richter et al., J. Chem. Phys. 120, 1306 (2004)], all eigenstates up to 4000 cm(-1) are calculated. We simulate the dynamics during and after excitation by an electromagnetic pulse whose parameters are chosen to efficiently trigger the isomerization. Our investigations show that there is a selective isomerization pathway.

The effect of pulsed electromagnetic fields on metal films, which are the basis of modern micro- and nanoelectronics, can lead to changes in their conductivity characteristics and surface properties. The paper aims to study the effect of electromagnetic pulses on the surface condition of thin metallic films of Bi, Cr and Fe and to investigate the effect of electromagnetic pulses on their conductivity and conductivity variations of the films. Surface roughness measurements were performed using a SOLVER PRO probe scanning microscope. In order to study the fluctuations of the film conductivity, a setup was set up that allowed measurements to be made around the clock for several months. The samples were exposed to nanosecond electromagnetic pulses without carrier frequency for 30 minutes. It was found that such exposure most strongly changed the surface roughness of chromium film, to a lesser extent - bismuth film, and for iron film exposure did not cause significant changes in the surface. The iron film also proved to be the most resistant to exposure in the conductivity study. Its resistivity and variation remained virtually unchanged. Exposure of the film to bismuth resulted in a 2–3 times decrease in the average number of conductivity jumps and bursts. Exposure to chromium film resulted in a similar effect and a twofold decrease in the level of small-scale fluctuations of electrical conductivity.

In a surface-tension measurement of a solution by a drop volume method, a magnetic force was applied by a pulsed electromagnet (<15T) and a static permanent magnet (0.55T) in order to investigate the effect of a magnetic force. In the drop volume method, a drop of MnCl2 solution was formed at the end of a glass capillary that had 0.73 mmφ in outer diameter, using a syringe pump. From the droped volume of the aqueous solution, the surface tension was measured. When a magnetic field gradient was applied to the droplet formed at the capillary end, a smaller droplet was droped than that of the volume in the absence of a magnetic field. In case of a static magnetic field, the effect was well explained by the magnetic gravity force added to the original garavity force. On the other hand, a pulsed magnetic force of 0.43 ms or 0.80 ms was not enough to make the drop fall, because the pulse duration was too short to pull down the droplet. This result required the introduction of an effciency factor of 0.01∼0.97, depending on the pulse duration and the magnetic susceptibility of the sample solution. Furthermore, the pulsed magnetic-field experiment allowed to esitimate the relaxation time of a droplet as being 7.8 ms, which implied that the magnetic filed had to continue for at least this time to be droped. Based on the present study, it has been suggested that a simultaneous measurment of surface tention and magnetic susceptivility was plausible by using a drop-volume method under a static magnetic field, or a pulsed magnetic field.

We develop farther our “three-level” approach to graphene metamaterials including “metamaterial treatment” of 2D beams of electron (BE) in graphene with 2D inhomogeneous and nonlinear electromagnetic waves in graphene-dielecric multlayered structres. A possibility of resonant behaviour of the components of the electron disrribution function in 2D “diffraction grating”, with 1D periodicity along a direction of beam propagation, is shown, first. The theory of 2D electromagnetic (EM) pulse propagation through multilayered graphene-dielectric structure with electron nonlinearity and “transmission bistability” is developed.

The spin and orbital angular momentum carried by electromagnetic pulses open new perspectives to control nonlinear processes in light-matter interactions, with a wealth of potential applications. In this work, we use time-dependent density functional theory (TDDFT) to study the nonlinear optical response of a free-electron plasmonic nanowire to an intense, circularly polarized electromagnetic pulse. In contrast to the well-studied case of the linear polarization, we find that the nth harmonic optical response to circularly polarized light is determined by the multipole moment of order n of the induced nonlinear charge density that rotates around the nanowire axis at the fundamental frequency. As a consequence, the frequency conversion in the far field is suppressed, whereas electric near fields at all harmonic frequencies are induced in the proximity of the nanowire surface. These near fields are circularly polarized with handedness opposite to that of the incident pulse, thus producing an inversion of the spin angular momentum. An analytical approach based on general symmetry constraints nicely explains our numerical findings and allows for generalization of the TDDFT results. This work thus offers new insights into nonlinear optical processes in nanoscale plasmonic nanostructures that allow for the manipulation of the angular momentum of light at harmonic frequencies.