The electromagnetic radiation of a charge moving in an infinite 3D structure made parallel wires is considered. periods the are assumed to be small; therefore, it can described by effective permittivity tensor. velocity perpendicular wires. Analytical and numerical investigations performed, some unusual properties noted. It shown that propagates along concentrates near certain rays behind charge. wave field does not vary with distance from these (if energy loss medium negligible). prospects...

We analyze the radiation from a charged particle crossing boundary between an ordinary medium and "left-handed" metamaterial. obtain exact approximate expressions for field components develop algorithms their computation. The spatial in this system can be separated into three distinct components, corresponding to transition having relatively large magnitude, Cherenkov radiation, reversed Cherenkov-transition (RCTR). last one is explained by reflection refraction of at interface. Conditions...

We analyze the electromagnetic field of a moving point charge in presence ``left-handed'' medium (LHM). First, case uniform motion infinite LHM was considered. Using complex function theory methods, we decomposed total into ``quasi-Coulomb'' field, wave (Cherenkov radiation) and ``plasma trace.'' In addition, an effective numerical algorithm developed for computation, typical plots were presented. It shown that lags behind more so than it does ordinary medium. Furthermore, investigated...

We analyze radiation produced by an ultrarelativistic charge as it exits the open end of a cylindrical waveguide with dielectric lining. The can be either orthogonal to structure axis or skewed. To obtain terahertz from waveguides centimeter millimeter radii, we consider high order TM(0m) modes driven beam. integral representation which describes single mode in Fraunhofer zone. perform series numerical calculations for structures look promising generation THz radiation. It is shown that...

We analyze the electromagnetic field generated by a point charge intersecting interface between vacuum and nonmagnetic anisotropic medium with plasma-type dispersion of dielectric permittivity tensor. After penetrating medium, moves along its main axis. The total is presented as sum self-field (i.e., in corresponding unbounded medium) scattered associated boundary influence. show that considered divided into quasistatic wave (the so-called ``plasma trace'' absent case under consideration)....

We report on a dielectric target that concentrates Cherenkov radiation into small spatial area. In contrast to traditional devices, this can focus almost all of the without using additional lenses or mirrors. consider case where is produced by point charge moving along axis cylindrical channel inside an axially symmetrical target. The specific form determined laws ray optics. field calculated aperture integration method determine near focus. Typical plots and distribution outside are...

We analyze the electromagnetic field of a charge crossing boundary between vacuum and cold plasma in waveguide. obtain exact expressions for components spectral density transition radiation. With steepest descent technique, we investigate components. show that has different structure than plasma. also develop an algorithm computation based on certain transformation integration path. The behavior depending distance time frequency are explored velocities. Some important physical effects noted....

The electromagnetic fields of charges moving along the boundary a ``wire metamaterial'' perpendicularly to wires are investigated. metamaterial under consideration represents volume-periodic structure thin parallel located in square lattice. This is described by an effective permittivity tensor and exhibits both spatial frequency dispersion. It shown that charge generates nondivergent radiation, as case infinite metamaterial. However, unlike infinite-metamaterial case, radiation concentrates...

Some of the problems with theory moving charge radiation in media frequency dispersion are analyzed. First, some general properties integrals for field components described. The results applied to cases passive and active media. In one instance, a an arbitrary number resonances is considered. Components have been presented as sum "quasi-Coulomb" field, wave "plasma trace." another example, case medium two resonant frequencies It has demonstrated that amplified even purely real refractive...

We present a method to determine the effective parameters of periodic structure with small spacing. This technique is analogous averaged boundary condition applied planar structures. The permittivity from parallel wires dielectric and magnetic coating was obtained. It contains an plasma frequency some parameter that responsible for spatial dispersion. dependences these on electromagnetic geometric characteristics were analysed. Particularly, it shown role dispersion decreases if we increase...

We analyze the electromagnetic field of a charged particle moving uniformly in circular waveguide and crossing boundary between dielectric vacuum. Our study focuses on case when Cherenkov radiation is generated dielectric. Analytical numerical investigation modes performed. show that large can be excited vacuum area. The mode amplitudes greater than those from Gaussian bunch also studied. note effect under consideration used to generate quasimonochromatic or multimode radiation.

The Vavilov-Cherenkov radiation of a charge moving along the main axis an anisotropic uniaxial nongyrotropic medium with resonant-type dispersion is analyzed. This model typical both for crystals and some metamaterials. analytical results obtained using complex plane analysis corresponding computed examples electromagnetic field components energy patterns are given. presented as sum quasi-Coulomb (the plasma oscillations not generated in case under consideration). classification media...

The electromagnetic field of a point charge moving in "wire metamaterial" parallel to the wires is investigated. metamaterial under consideration periodic structure perfect conductors with dielectric or magnetic coating. spacing assumed be much less than typical wavelengths; therefore, can described as an anisotropic medium that exhibits both frequency and spatial dispersions. In this paper, general expressions for components have been obtained. A comparison cold plasma has performed. shown...

An approximate method for calculating the radiation from a moving charge in presence of dielectric object is developed. The composed two steps. first step calculation field medium without considering external boundaries object, and second an (ray-optical) wave propagation outside object. As test problem, we consider case crossing plate. Computations are performed using exact methods. It shown that results agree well. Additionally, apply under consideration to cone-shaped with vacuum channel....

We proceed with investigation of specific dielectric target that effectively concentrates Cherenkov radiation from a charged particle bunch into small vicinity the focus point located at symmetry axis target. The case "non-ideal concentration" where charge velocity differs designed one was considered theoretically in our previous paper. In particular, we have noted geometrical rays form caustics this case, and areas concentration are shifted respect to point. Since direction shift relates...

Bunch radiation in periodical waveguides was mainly analyzed for situations when wavelengths are comparable to the structure period (Smith-Purcell emission). However, it is also interesting study long wave with which much greater than period. In this paper, electromagnetic field using method of equivalent boundary conditions. According approach, exact conditions on complex periodic surface replaced certain must be fulfilled smooth surface. We consider a vacuum circular waveguide corrugated...

The radiation of a charge moving in the presence large (compared with wavelengths under consideration) dielectric prism two different configurations is studied: case (I), channel, and (II), along prism's face. approximate method that combines an exact solution certain "key problems" (without external boundaries object) ray-optics technique for field outside used. A general analytical problems obtained, particular small angles considered, algorithm computation developed. computed results are...

The present paper addresses the electromagnetic field generated by a point charge or small charged particle bunch moving with constant velocity in cold magnetized plasma, along external magnetic field. Attention is focused on case of ultrarelativistic motion. surrounding investigated both analytically and numerically. In analytical study, we obtain rigorous decomposition into quasistatic wave components. Beating behavior far-field zone harmonic vicinity trajectory are found using suitable...

The electromagnetic field of a bunch moving in the presence plane grid composed thin parallel wires is considered by using averaged boundary conditions method. Two different cases motion are examined. In first one, moves at constant distance from orthogonally to wires. excited surface wave presented form spectral integral for with an arbitrary longitudinal profile. propagates along and does not decay (if dissipation negligible). Energy losses over unit path obtained. second case, crosses...

Radiation generated by a charge moving in vacuum channel through dielectric cone is analyzed. The size of the conical target assumed to be much greater than wavelengths under consideration. We calculate wave field outside using Stratton-Chu formulas (``aperture integrals''). This work focuses mainly on investigation electromagnetic far-field area (Fraunhofer area). representative radiation patterns and show that typically maximal direction one refracted rays. However, specific case where ray...

We develop an original method for calculation of radiation from a charge moving in the presence dielectric object. The can be applied to objects which are larger than wavelengths under consideration. First, field infinite medium (without external boundaries) is calculated. Further at boundary object ("the aperture") found using Snell's and Fresnel's laws. At final step this technique, we calculate outside target Stratton-Chu formulae ("aperture integrals"). Contrary ray-optic valid...

We analyze the electromagnetic field of a charged particle that uniformly moves in circular waveguide and crosses boundary between dielectric medium, which possesses frequency dispersion resonant type, vacuum area. The investigation mode components is analytically numerically performed. It shown Cherenkov radiation (CR) can penetrate through boundary, Cherenkov-transition (CTR) be excited region. conditions for this effect are obtained. CTR composed single (compared with nondispersive...

The radiation of a charged-particle bunch moving perpendicularly to semi-infinite plane grid composed thin parallel wires is analyzed using the method averaged boundary conditions (the period assumed be much less than wavelengths under investigation). We perform an analysis volume and surface waves generated by finite length. It shown that patterns fundamentally differ from those arise in case infinite grid. properties are similar Cherenkov three-dimensional wire metamaterial. These...

We analyze the interaction between a charge and its electromagnetic field in case of moving waveguide intersecting boundary two nondispersive media. The total work done by on is calculated both analytically numerically. It shown that positive under certain conditions, force actuating accelerating. A physical interpretation this phenomenon from point view energy conservation given. kinetic gain per unit length for all time motion analyzed as well.