A possible mechanism of current in medium under electromagnetic wave

In this paper a possible mechanism of current in medium is presented. Comparison between this current and the magnetization current was made. Expression for this current was derived. This work is helpful to understanding the interaction between medium and electromagnetic wave.     

Effect of gravitational radiation upon electromagnetic waves in a dispersive medium

We show that linearized gravitational radiation produces fluctuations in intensity and position of a distant source if the ray travels in a dispersive medium. The effect, however, depends upon the nongeodesic character of the ray and does not occur in an electrostatic plasma. When the index of refraction n is greater than unity a Cerenkov type resonance produces scintillation proportional to D _O ^3/2 (D _O being the distance of the source) and a dancing proportional to D _O ^1/2 if, instead, n<1 the scintillation behaves like D _O and the dancing does not diverge as D _O . The calculation is performed in detail for a random and isotropic spectrum of gravitational waves W(). This effect allows one to set an upper limit to W() at the frequency at which the fluctuations are observed, but for the rarified interstellar and intergalactic plasmas these limits are not very interesting.     

Transformation of electromagnetic radiation at moving inhomogeneities of a medium

The possibility of a significant up-conversion of the electromagnetic-radiation frequency due to its Doppler shift by ultrarelativistic nonlinear-medium inhomogeneities induced by high-intensity counterpropagating radiation pulses is analyzed. It is shown that the efficiency of parametric redistribution increases resonantly as the velocity of the inhomogeneity approaches the phase velocity of the high-frequency radiation.     

Nonstationary heating of a plane-layered medium by pulsed electromagnetic radiation

Nonstationary heat exchange in a nontransparent plane-layered medium irradiated with a directional beam of pulsed radiation is investigated theoretically. The radiation is absorbed on the irradiated surface, which becomes a distributed source of heat. The propagation of the heat into the layers is described by the heat-conduction equation with nonlinear boundary conditions, which take into account convection and heat exchange with the radiation. Dimensionless parameters, on which the solution depends, are obtained, and their effect on the change of the surface temperatures of the layers with time for one- and two-layered media and also on the heat pulse transmitted through the medium is analyzed.M. V. Lomonosov Moscow State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 115–121, November, 1992.     

Anisotropy of the velocity space of electromagnetic radiation in a moving medium

Anisotropy arising in moving media is considered. In these media, the phase velocity of light nonlinearly depends on the velocity vector field of the medium due to anisotropic binding forces between lattice atoms. Observations of the optical anisotropy of light in a rotating optically transparent medium are discussed. Laser radiation with wavelength ?? = 0.632991 ± 1 × 10^?7 ??m propagating in an interferometer was passed through a rotating optical disk D = 62 mm in diameter. The projection of the beam??s path length in the medium onto the flat surface of the disk is l = 41 mm; the refractive index of the glass and its thickness are, respectively, n = 1.71250 for ?? = 632.8 nm and 10 mm; and the angle of incidence of the beam on the flat surface of the disk is ?₀ = 60°. The optical disk is rotated in two directions, and its rotation frequency may reach 250 Hz. Experimental data confirm the linear dependence of the fringe shift on the velocity of the medium up to 29.6 m/s. The measurement accuracy is sufficient to detect angular variations ??? = 3 × 10^?5 in the position of fringes at a fixed rotation velocity of the optical disk.     

Coherent X-ray radiation from a relativistic electron in a combined medium

A theory of coherent X-ray radiation from a relativistic electron crossing a combined medium that consists of amorphous and crystal plates is constructed within the dynamic diffraction theory. The field reflection asymmetry relative to the target surface determined by the angle between the atomic planes and the target surface is taken into account in the theory. The expressions describing the spectral-angular densities of parametric X-ray and diffracted transition radiations in this medium are derived and investigated.     

光与介质作用下的一种分子电流机制

光与介质分子相互作用是一个活跃的研究领域,新的现象、技术和理论不断出现,原有理论对解释某些新的现象遇到困难.本文应用法拉第电磁感应原理研究了分子中电子云与光波之间的相互作用,提出了在光波作用下介质中存在的一种分子电流机制,这种电流的密度随磁场的时间变化率增加而增大,它不同于介质分子的极化电流和磁化电流.这些工作有助于深入认识光波与介质之间的相互作用.     

Change in the electromagnetic field frequency because of stimulated radiation in a medium

The spectrum of a two-photon electromagnetic field in a transparent dispersing medium consists of three branches. Excitation of the secondary branches of the spectrum implies a change in the electromagnetic field frequency during passage through a medium of finite size if excited impurity atoms are present.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 65–69, May, 1982.I am grateful to the participants of the seminar supervised by V. L. Bonch-Bruevich for favorable remarks.     

Transport of light radiation in a spatially finite three-dimensional scattering medium

We propose a new method for solving radiation transport problems, which permits including in analytic form for the case of normal incidence the effect of spatial finiteness of the scattering medium. The formation of the light field accompanying changes in the optical parameters and optical dimensions of the medium is analyzed.this paper, we examine the simplest case of a geometry of a scattering medium in the form of a parallelipiped with optical length _x, height _y, and width _z. The analysis is performed for the case =1, _y = _z with the latter varying in the range 0.1 to . The results obtained show that the light field depends strongly on the optical dimensions of the medium. The limiting values of the optical dimensions (_y = _z), beginning with which the spatial finiteness of the medium can be neglected, are determined.Translated from Izvestiya Vysshikh Uchebnykh Zavednii, Fizika, No. 8, pp. 82–85, August, 1982.     

Passive location of transition electromagnetic radiation of a beam electron emitter

In the study by Chudnovskii et al. (Russ. J. Phys. Chem. B., 2012, no. 2), it was shown that transition electromagnetic radiation appears between the linear-accelerator diaphragm and a target. In this case, produced bremsstrahlung leads to the generation of high-energy γ quanta on the accelerator target. The theoretical model of transition radiation that was developed in the aforementioned study and its experimental verification make it possible to closely approach the solution of the problem of detecting a beam-radiator source and determining its coordinates and engineering parameters. It is shown that for linear-accelerator pumping frequencies of 1, 3, and 10 GHz, the reliable location in space is possible for distances from the Earth’s surface of 6000, 2400, and 600 km, respectively. In this case, the minimum signal-to-noise ratio must exceed 2–3.     

Electric dipole mechanism of the generation of electromagnetic radiation due to the spin transport in an InSb semiconductor

Conditions for the generation of electromagnetic radiation by spin-polarized electron transport through a junction made on the basis of an InSb semiconductor and an HgCr₂Se₄ or Co₂MnSb ferromagnetic material are investigated. It is shown that electromagnetic radiation from the junction appears only when the electron flow passing from the ferromagnet to the InSb semiconductor is polarized. The radiation intensity is found to depend on the direction of the external magnetic field with respect to the InSb crystal axes. Maximum intensity values are observed for the field directions corresponding to the highest probability of electric dipole spin transitions between Zeeman levels.     

Transformation of electromagnetic radiation by rapidly moving inhomogeneities of a transparent medium

A theory of reflection and transmission of electromagnetic radiation by inhomogeneities of the parameters of a static transparent medium moving at the velocity of light is developed. Expressions are obtained for the Doppler frequency shift of radiation; it turns out that, under the condition of pronounced frequency dispersion, the frequency of incident radiation corresponds to two frequencies of reflected radiation (complementary waves). It is found that, as the velocity of an inhomogeneity tends to the phase velocity of radiation in the medium, the reflection and transmission coefficients of radiation by the inhomogeneity indefinitely increase. It is shown that the electromagnetic radiation frequency may increase severalfold, with a transformation coefficient of about unity, due to the Doppler shift by the inhomogeneities of a nonlinear medium that are induced by pulses (solitons) of intense counterpropagating radiation.     

A new spin effect in photoemission with unpolarized light: Experimental evidence of spin polarized electrons in normal emission from Pt(111) and Au(111)

Unpolarized light ejects spin polarized electrons from Pt(111) and Au(111) even if the electron emission occurs normal to the surface. For off normal incidence of 11.8 eV, 16.9 eV, and 21.2 eV radiation, and for the main peaks in the photoemission spectra, a degree of spin polarization of up to 30% or more is found for the spin polarization component P _y perpendicular to the reaction plane. A crystal rotation about its surface normal does not change P _y . P _y is largest for transitions from bands with symmetry ₆ ³ . All these experimental findings agree with a recent theoretical prediction [1] of a new spin effect by Tamura and Feder.     

Low-frequency electromagnetic radiation generated by electron beams in gases

13-MeV electron beams are shown to generate low-frequency electromagnetic radiation in the gaseous medium of a 100-m-long dielectric electron pipe.     

A new mechanism of anomalous penetration of electromagnetic waves into a metal

The high-frequency phenomena occuring in metals have been considered taking into account the multi-channel mode of carrier reflection from a perfect boundary. As has been found, umklapp processes can bring about an anomalous transparency of metallic plates in a wide range of magnetic-field strengths and electromagnetic-wave frequencies.     

Scattering of electromagnetic radiation by an ionized gaseous medium

A statistical model is proposed for the scattering of microwave radiation by a weakly ionized gaseous medium irradiated by hard ionizing radiation. It is shown that owing to the correlation of the positions of the elementary scatterers, the predominant contribution comes from scattering on the tracks of the high-energy ionizing particles. The prospects for radar detection of the tracks of radioactive ionization of air are assessed. The maximum distance for radar detection of a cloud of radioactive contamination is calculated as a function of the second release of nuclide activity. An analysis is made of the dependence of the detection threshold on the type of radioactivity, observation geometry, and wavelength of the probe radiation. Zh. Tekh. Fiz. 67, 76–82 (February 1997)     

Transition radiation of surface electromagnetic waves by electron bunches in a cylindrical waveguide

Transition surface electromagnetic radiation from electron bunches that cross a metal-insulator-semiconductor structure in a perfectly conducting semi-infinite cylindrical waveguide is studied. It is shown that, using a periodic sequence (train) of electron bunches, a particular surface waveguide eigenmode can be amplified by bringing its frequency to resonance with the bunch repetition frequency in the train. Those eigenmodes are amplified most efficiently whose frequency falls into the range occupied by the first maximum of the geometric factor of one bunch.