Intense Electromagnetic Pulses Research Articles

Relativistic electromagnetic flat top solitons and their stability

The inclusion of ion response in the study of relativistically intense electromagnetic laser pulse propagation in plasma yields certain distinct varieties of single peak solitonic structures. A flat top slow moving structure (for which the various fields have a flat profile over a wide spatial range) is one such solution. A detailed characterization of these solutions along with the eigen spectrum of their formation in the parameter space has been presented. The evolution of this particular solution is studied in detail with the help of a coupled fluid Maxwell set of equations. The study shows that the flat top solution is unstable. The instability is characterized as the backward Brillouin instability for which the electron quiver velocity plays the role of the effective temperature.

On the design of experiments for the study of extreme field limits in the interaction of laser with ultrarelativistic electron beam

We propose the experiments on the collision of laser light and high intensity electromagnetic pulses generated by relativistic flying mirrors, with electron bunches produced by a conventional accelerator and with laser wake field accelerated electrons for studying extreme field limits in the nonlinear interaction of electromagnetic waves. The regimes of dominant radiation reaction, which completely changes the electromagnetic wave-matter interaction, will be revealed in the laser plasma experiments. This will result in a new powerful source of ultra short high brightness gamma-ray pulses. A possibility of the demonstration of the electron-positron pair creation in vacuum in a multi-photon processes can be realized. This will allow modeling under terrestrial laboratory conditions neutron star magnetospheres, cosmological gamma ray bursts and the Leptonic Era of the Universe.

Interaction of Atomic Clusters with Intense Attosecond Pulses

AbstractWe consider the interaction between intense attosecond electromagnetic pulses and the Van der Waals atomic clusters. The important conclusion has been made that the cross section for scattering of soft x‐ray by Xe clusters increases resonantly when the photon energy is of the order of 100‐150 eV. This phenomenon is explained by resonance excitation of the giant resonance at the collection oscillations of Xe atomic 4d‐shell (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Relativistic laser-plasma interactions in the quantum regime

We consider nonlinear interactions between a relativistically strong laser beam and a plasma in the quantum regime. The collective behavior of electrons is modeled by a Klein-Gordon equation, which is nonlinearly coupled with the electromagnetic wave through the Maxwell and Poisson equations. This allows us to study nonlinear interactions between arbitrarily large-amplitude electromagnetic waves and a quantum plasma. We have used our system of nonlinear equations to study theoretically the parametric instabilities involving stimulated Raman scattering and modulational instabilities. A model for quasi-steady-state propagating electromagnetic wave packets is also derived, and which shows possibility of localized solitary structures in a quantum plasma. Numerical simulations demonstrate collapse and acceleration of electrons in the nonlinear stage of the modulational instability, as well as possibility of the wake-field acceleration of electrons to relativistic speeds by short laser pulses at nanometer length scales. Our study is relevant for understanding the localization of intense electromagnetic pulses in a quantum plasma with extremely high electron densities and relatively low temperature.

New Materials Properties Induced by Intense THz Electromagnetic Pulse(Current Topics)

New Materials Properties Induced by Intense THz Electromagnetic Pulse(Current Topics)

Swarm of ultra-high intensity attosecond pulses from laser-plasma interaction

We report on the realistic scheme of intense X-rays and γ-radiation generation in a laser interaction with thin foils. It is based on the relativistic mirror concept, i.e., a flying thin plasma slab interacts with a counterpropagating laser pulse, reflecting part of it in the form of an intense ultra-short electromagnetic pulse having an up-shifted frequency. A series of relativistic mirrors is generated in the interaction of the intense laser with a thin foil target as the pulse tears off and accelerates thin electron layers. A counterpropagating pulse is reflected by these flying layers in the form of a swarm of ultra-short pulses resulting in a significant energy gain of the reflected radiation due to the momentum transfer from flying layers.

A survey of ELF and VLF research on lightning‐ionosphere interactions and causative discharges

Extremely low frequency (ELF) and very low frequency (VLF) observations have formed the cornerstone of measurement and interpretation of effects of lightning discharges on the overlying upper atmospheric regions, as well as near‐Earth space. ELF (0.3–3 kHz) and VLF (3–30 kHz) wave energy released by lightning discharges is often the agent of modification of the lower ionospheric medium that results in the conductivity changes and the excitation of optical emissions that constitute transient luminous events (TLEs). In addition, the resultant ionospheric changes are best (and often uniquely) observable as perturbations of subionospherically propagating VLF signals. In fact, some of the earliest evidence for direct disturbances of the lower ionosphere in association with lightning discharges was obtained in the course of the study of such VLF perturbations. Measurements of the detailed ELF and VLF waveforms of parent lightning discharges that produce TLEs and terrestrial gamma ray flashes (TGFs) have also been very fruitful, often revealing properties of such discharges that maximize ionospheric effects, such as generation of intense electromagnetic pulses (EMPs) or removal of large quantities of charge. In this paper, we provide a review of the development of ELF and VLF measurements, both from a historical point of view and from the point of view of their relationship to optical and other observations of ionospheric effects of lightning discharges.

The damage effect and mechanism of the bipolar transistor induced by the intense electromagnetic pulse

A study of the internal damage process and mechanism of the typical n+-p-n-n+ structure bipolar transistor induced by the intense electromagnetic pulse (EMP) is carried out in this paper from the variation analysis of the distribution of the electric field,the current density and the temperature. Research shows that the damage position of the bipolar transistor is different with the different magnitude of the injecting voltage,when the magnitude of the injecting voltage is low the damage will appear firstly near the collector region under the center of the emitter region,and when the magnitude of the injecting voltage is sufficiently high the damage will appear firstly at the edge of the base near the emitter due to the breakdown of the PIN structure composed of the base-epitaxial layer-collector. Adopting the data analysis software,the relation equation between the device damage power P and the pulse width T under different injecting voltage is obtained. Owing to the variety of the device damage energy,it is demonstrated that the empirical formulas of the intense electromagnetic pulse P=AT-1 (A is a constant) is modified to P=AT-1.4 for the bipolar transistor.

Long-time solution of the time-dependent Schrödinger equation for an atom in an electromagnetic field using complex coordinate contours

We demonstrate that exterior complex scaling (ECS) can be used to impose outgoing wave boundary conditions exactly on solutions of the time-dependent Schr\"odinger equation for atoms in intense electromagnetic pulses using finite grid methods. The procedure is formally exact when applied in the appropriate gauge and is demonstrated in a calculation of high-harmonic generation in which multiphoton resonances are seen for long pulse durations. However, we also demonstrate that while the application of ECS in this way is formally exact, numerical error can appear for long-time propagations that can only be controlled by extending the finite grid. A mathematical analysis of the origins of that numerical error, illustrated with an analytically solvable model, is also given.

Ensemble of ultra-high intensity attosecond pulses from laser–plasma interaction

The efficient generation of intense X-rays and γ-radiation is studied. The scheme is based on the relativistic mirror concept, i.e., a flying thin plasma slab interacts with a counterpropagating laser pulse, reflecting part of it in the form of an intense ultra-short electromagnetic pulse having an up-shifted frequency. In the proposed scheme a series of relativistic mirrors is generated in the interaction of the intense laser with a thin foil target as the pulse tears off and accelerates thin electron layers. A counterpropagating pulse is reflected by these flying layers in the form of an ensemble of ultra-short pulses resulting in a significant energy gain of the reflected radiation due to the momentum transfer from flying layers.

The time-dependent Dirac equation for atoms exposed to short intense electromagnetic pulses

The time dependent Dirac equation for hydrogen-like systems exposed to intense laser pulses, is solved numerically and compared to the corresponding prediction from the non-relativistic Schrödinger equation. It is found that virtual electron-positron pairs are instrumental for a correct description of effects beyond the dipole approximation. Relativistic effects in the ionization dynamics of highly charged systems are studied

Solution of the Dirac equation for hydrogenlike systems exposed to intense electromagnetic pulses

The time-dependent Dirac equation is solved numerically and compared to the corresponding prediction of the nonrelativistic Schr\"odinger equation for hydrogenlike systems exposed to intense laser pulses. It is found that for a correct description of effects beyond the dipole approximation, virtual electron-positron pairs can be very important. Relativistic effects in the ionization dynamics of highly charged systems are studied.

Stability of a plasma foil in the radiation pressure dominated regime

The stability of a thin plasma foil accelerated to relativistic velocities by the radiation pressure of an ultra high intensity electromagnetic pulse is investigated. The effects of the onset of a Rayleigh-Taylor-like instability are discussed in the context of the ion acceleration process during the interaction of the laser pulse with the plasma. It is stressed that the experimental study of this advanced laser plasma interaction regime will be accessible within the framework of the ELI experiment and will be of relevance for our understanding of high energy astrophysical phenomena.

Image plate response for conditions relevant to laser–plasma interaction experiments

We have measured the absolute response and detective quantum efficiency of image plates (IPs) for 5.9 keV x-rays using a calibrated iron-55 source. The types of IPs considered in this study are now commonly used as x-ray detectors in high-intensity laser–plasma interaction experiments, where conventional CCD fails because of the intense electromagnetic pulse that follows a high-intensity shot. Since the plates are not read out immediately after each laser shot, a detailed fading analysis of the plates is also presented. This work is important for future implementation of IPs as absolute x-ray photon detectors in large-scale laser facilities.

Photon Bubbles and Ion Acceleration in a Plasma Dominated by the Radiation Pressure of an Electromagnetic Pulse

The stability of a thin plasma foil accelerated by the radiation pressure of a high intensity electromagnetic (e.m.) pulse is investigated analytically and with particle in cell numerical simulations. It is shown that the onset of a Rayleigh-Taylor-like instability can lead to transverse bunching of the foil and to broadening of the energy spectrum of fast ions. The use of a properly tailored e.m. pulse with a sharp intensity rise can stabilize the foil acceleration.

Nonlinear propagation of broadband intense electromagnetic waves in an electron-positron plasma

A kinetic equation describing the nonlinear evolution of intense electromagnetic pulses in electron-positron (e-p) plasmas is presented. The modulational instability is analyzed for a relativistically intense partially coherent pulse, and it is found that the modulational instability is inhibited by the spectral pulse broadening. A numerical study for the one-dimensional kinetic photon equation is presented. Computer simulations reveal a Fermi-Pasta-Ulam-type recurrence phenomenon for localized broadband pulses. The results should be of importance in understanding the nonlinear propagation of broadband intense electromagnetic pulses in e-p plasmas in laser-plasma systems as well as in astrophysical plasma settings.

H+2 ionization by ultra-short electromagnetic pulses investigated through a non-perturbative Coulomb–Volkov approach

The sudden Coulomb–Volkov theoretical approximation has been shown to well describe atomic ionization by intense and ultra-short electromagnetic pulses, such as pulses generated by very fast highly-charged ions. This approach is extended here to investigate single ionization of homonuclear diatomic molecules by such pulses in the framework of one-active electron. Under particular conditions, a Young-like interference formula can approximately be factored out. Present calculations show interference effects originating from the molecular two-centre structure. Fivefold differential angular distributions of the ejected electron are studied as a function of the molecular orientation and internuclear distance. Both non-perturbative and perturbative regimes are examined. In the non-perturbative case, an interference pattern is visible but a main lobe, opposite to the electric field polarization direction, dominates the angular distribution. In contrast, in perturbation conditions the structure of interferences shows analogies to the Young-like interference pattern obtained in ionization of molecules by fast electron impacts. Finally, the strong dependence of these Young-like angular distributions on the internuclear distance is addressed.

Coulomb—Volkov approaches to atom ionization by short electromagnetic pulses

A non-perturbative approach based on Coulomb-Volkov-type states can predict both angular and energy distributions of electrons which are ejected when atoms interact with very short and intense electromagnetic pulses. For atomic hydrogen targets, this theory makes accurate predictions as long as the interaction time, both, does not exceed half the initial orbital period of the electron, and does not permit more than two oscillations of the electric field. For a given pulse, the results are all the better when the electric field amplitude is high and the initial quantum number is large. It might be well adapted to the study of ion impact ionization, i.e. when the electric field is created by a swift ion. Further, when the interaction betweeen an atom and a high frequency (X-UV) laser pulse is a perturbation, an alternative approach, also based on Coulomb—Volkov-type states, gives reliable results for Above Threshold Ionization (ATI). It provides accurate ATI spectra when both the photon energy is greater than the ionization potential and the total ionization probability does not exceed 20%. It is well suited to the investigation of ionization by the present-day high-harmonics laser pulses.

Lightning effects at high altitudes: sprites, elves, and terrestrial gamma ray flashes

A fascinating set of newly discovered complex phenomena indicate that thunderstorms and lightning discharges are strongly coupled to the overlying upper atmospheric regions. Lightning discharges at cloud altitudes (<20 km) affect altitudes >40 km either via the release of intense electromagnetic pulses (EMPs) and/or the production of intense quasi-static electric (QE) fields. The intense transient QE fields of up to ∼1 kV·m −1, which for positive CG discharges is directed downwards, can avalanche accelerate upward-driven runaway MeV electron beams, producing brief (∼1 ms) flashes of gamma radiation. A spectacular manifestation of these intense fields is the so-called ‘Sprites’, large luminous discharges in the altitude range of ∼40 km to 90 km, which are produced by the heating of ambient electrons for a few to tens of milliseconds following intense lightning flashes. The so-called ‘Elves’ are optical flashes which last much shorter (<1 ms) than sprites, and are typically limited to 80–95 km altitudes with much larger (up to 600 km) lateral extent, being produced by the heating, ionization, and optical emissions due to the EMPs radiated by both positive and negative lightning discharges. To cite this article: U.S. Inan, C. R. Physique 3 (2002) 1411–1421.

Response of a nonlinear magnetic medium to an incident intense electromagnetic pulse

Abstract Reflection of an intense electromagnetic wave pulse is considered from a class of strongly nonlinear magnetic media. It is shown that almost all the incident energy of the electromagnetic pulse can be reflected, and the polarization of the reflected wave will be rotated like magneto-optical Kerr effect. Also constitutive equations for those media are obtained by analytical solution of Maxwell equations. Such media can be of interest as a power limiters against powerful laser pulses.