Solar Radiation Scattering by Aerosol Axially Symmetric Objects

We have obtained analytical expressions for the scattering coefficient and the angular distribution of radiation for the aerosol train (tail) modeled by a homogeneous cylinder with given scattering coefficient and phase function of the elementary volume. The analytical formulas for the angular distribution of scattered radiation have been obtained in the single-scattering approximation. Using the Monte Carlo method, we have calculated the directional scattering coefficients of a homogeneous monodisperse tail consisting of spherical water particles with a mean radius of 1 μm for various diametrical optical thicknesses of the tail. The relations obtained can be used for passive remote sensing of aerosol air pollutions. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 5, pp. 604–610, September–October, 2005.     

Diffraction radiation of ultrarelativistic particles passing through a slit in a tilted screen

Diffraction radiation generated by relativistic particles passing through a slit in a tilted screen is proposed for nondestructive particle beam diagnostics. For ultrarelativistic particles with the Lorentz factor γ≫1, simple relations are derived for the field strength of diffraction radiation from a slit in a tilted perfectly conducting plane. It is shown that the total radiation loss is proportional to γ. The effect of the initial beam divergence on the angular distribution pattern of diffraction radiation is pointed out. A principal possibility of determining a beam divergence smaller than γ^-1 is demonstrated when measuring the angular distribution of radiation with a constant wavelength. Tomsk Polytechnical University. Translated from Izvestiya Vysshykh Uchebnykh Zavedenii, Fizika, No. 4, pp. 56–61, April, 2000.     

Observation of coherent X-ray production by 800-MeV electrons in a periodic triple-crystal target

The production of coherent x radiation by 800-MeV electrons in a target consisting of three 16-μm silicon crystals is investigated at the Tomsk synchrotron. The target structure makes it possible to observe from each crystal in turn, as the target is rotated, the radiation due to the summation of parametric x radiation (PXR) and the diffracted resonance transition radiation (DRTR) produced at the surfaces of the preceding crystals. The orientational dependence obtained shows that the contribution of the DRTR increases with the number of the crystal in the series, so that the angular density of the DRTR from the third crystal is approximately 1.7 times higher than the density of the PXR. Pis’ma Zh. éksp. Teor. Fiz. 65, No. 8, 594–599 (25 April 1997)     

Photoinduced improvement of the properties of light-emitting diodes

Results from studies of the effect of the action of optical radiation on the characteristics of light-emitting diodes (LEDs) produced using the binary heterostructure Ga_xAl_1−xAs (λ=0.88 μm) are presented. High sensitivity of the LED to the following parameters of the optical radiation is shown: flux density, quantum energy, and exposure dose. The action of optical radiation in the form of a band with a maximum at 255 nm on the LED heterostructures lowers the leakage current into the bulk, decreases the loss identified as surface leakage current by about an order of magnitude, increases the radiated power by 50–100% in the current region up to 10⁻³ A, and increases the overall light output of the diodes. Tomsk Polytechnic University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 109–114, August, 1997.     

Radiation scattering by finite dielectric cyclinders

The volumetric integral equation formalism (VIEF) is used to determine characteristics of scattering of radiation falling along the axis of dielectric cylinders that scatter the radiation. The spectral dependence of the extinction efficiency factor Q is studied with changes in the length l of the cylinder (300–2200 nm), its width d (100–300 nm), and the refraction index m (1.33–1.65). In the range of angles θ=0–180°, for a cylinder with l=700 nm, d=100 nm, and m=1.33, angular intensity distribution functions i_i and i₂ are calculated for the components of the scattered radiation that are polarized perpendicular and parallel to the plane of observation, respectively. No effect of scattered-radiation depolarization is found. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 2, pp. 256–260, March–April, 1998.     

Formation of a plane layer of plasma under irradiation by a soft X-ray source

We investigate theoretically the formation of a plasma in a plane layer of polymer foam (density ρ = 0.002 g/cm³ and thickness 800 μm) under the action of an external source of soft X-ray radiation under the conditions of PHELIX experiments. The incident flux is assumed to have a Planck’s distribution over the spectrum with T _rad = 20–40 eV. In numerical calculations, the flux of incident X-ray radiation and the spectral constants of the target substance are varied. The action of an external X-ray radiation source on a low-density foam substance with a density of 2 mg/cm³ causes a plasma to be formed with relatively homogeneous profiles of density and temperature T = 15–35 eV. Absorption of externalradiation energy is distributed in the volume. The plasma temperature increases with increase in the external energy, and the energy passed through the plasma also increases. The results prove to be sensitive to the values of optical constants used in numeral simulation. The spectral flux of external radiation passed through the plasma is chosen as a criterion of correctness of the optical constants used in the calculations. In future experiments using the PHELIX facility, we plan to investigate the slowing-down of an ion beam in a plasma formed as a result of indirect heating of low-density polymer triacetate cellulose (TAC) foam with densities ρ = 0.001–0.01 g/cm³ under the action of a pulse of X-ray radiation, into which the laser radiation is preliminarily transformed.     

Directionality and mode structure of radiation of semiconductor lasers with electron-beam pumping

We present results of investigations of the directionality diagram and mode structure of radiation of semiconductor lasers with electron pumping that have microrelief reflectors instead of a blind mirror and output mirrors, whose coefficient of reflection depends on the wavelength and the angle of light propagation. Application of such mirrors allows one to narrow the spectrum of output radiation of the lasers, simultaneously reducing the threshold and increasing the output power. The discovered multilobe structure of the directionality diagrams is explained on the basis of geometrical optics. The possibility of controlling the directionality of radiation depending on the spectral and angular characteristics of the output mirror is shown. Reported at the Second International Scientific and Technical Conference on Quantum Electronics, Minsk, November 23–25, 1998. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 5, pp. 092–697, Septemter–October, 1999.     

Radiation of slow electromagnetic waves in an isotropic medium with spatial dispersion

This paper discusses the distinctive features of radiation of electromagnetic waves with anomalously large values of the wave vector and small phase velocity that exist near narrow absorption lines. The distribution of radiated energy with respect to angle and frequency is calculated for Čerenkov radiation and bremsstrahlung of the slow waves. It is shown that the angular distribution of the slow-wave bremsstrahlung exhibits a characteristic maximum in the direction perpendicular to the plane of motion of the particles. Zh. éksp. Teor. Fiz. 112, 1557–1562 (November 1997)     

Stimulated and spontaneous far infra-red emission from uniaxially strained gapless Hg<Subscript>1−x</Subscript>Cd<Subscript>x</Subscript>Te

The intensive far infra-red irradiation in the range of 80–100 μm was observed in uniaxially strained gapless p-Hg_1−xCd_xTe (MCT) with x = 0.14 in the strong electric field. The inverse occupation in strained MCT is created because the hot electrons distribution occurs in the c-band under impact ionization, while the holes are localized near the v-band top. The probability of band-to-band radiative transition increases dramatically when the acceptor level becomes resonance in the v-band. At threshold values of strain and electric field (P = 2.5–2.7 kbar, E = 50–55 V/cm), increase in irradiation (by 3 orders of magnitude) and increase in current (by 4–6 times) occur.     

Magnetic phase transitions in TbNi<Subscript>5</Subscript> single crystal: Bulk properties and neutron diffraction studies

The angular dependence of the intensity of CK_α radiation measured from a film of oriented carbon nanotubes shows an increase in the yield of x-ray fluorescence along the growth direction of the nanotubes. The angular distribution of the intensity of scattered x rays is close in magnitude to the angular distribution of the directivity of nanotubes in the film that is determined by analyzing an electron-microscope image. To explain the propagation of radiation along the nanotubes, two mechanisms are proposed on the basis of reflection from inner walls of a tube (channeling) and an anomalous dispersion of CK_α photons in the carbon medium.     

Cyclotron scattering with mode switching in plasma on degenerate stars I. Radiative relaxation in a homogeneous rarefied plasma

Population balance equations for the Landau levels in a non-relativistic rarefied plasma are written for arbitrary polarization of cyclotron modes. Self-consistent evolution of the transverse distribution of electrons interacting, by virtue of the cyclotron processes, with an isotropic radiation at frequencies near the first harmonic of the electron gyrofrequency is studied. The spectrum of the relaxation times of the system is found for a fixed radiation intensity. It is shown that the time of cyclotron relaxation under the action of the first-harmonic radiation with broad angular and frequency spectra is entirely determined by the rate of spontaneous processes and does not depend on the radiation intensity. Cyclotron radiation transfer coefficients which account for the process of mode switching at the first harmonic are obtained. Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 11, pp. 1035–1053, November, 1999.     

Long-range correlations upon wave propagation in random media under the conditions of strong internal reflection from their boundaries

The large-scale behavior of the spatial distribution of radiation in a random medium is investigated under the assumption of strong internal reflection from its boundaries. The qualitative variations of the angular coherent backscattering spectrum and long-range spatial intensity correlations in the transmitted and reflected radiation fluxes are predicted. Zh. éksp. Teor. Fiz. 113, 291–312 (January 1998)     

Angular distribution of electrons during two-photon ionization of atoms by elliptically polarized radiation

Two-photon ionization of the hydrogen-like uranium ion by elliptically polarized radiation is investigated in the present work. It is demonstrated that the fundamental effect of interference of the probability amplitudes arises in the angular photoelectron distribution when the degree of ellipticity of ionizing radiation is varied. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 39–41, December, 2008.     

Transition radiation of a charge in media with a nonuniform potential

The influence of a potential barrier on the transition radiation in the form of volume and surface electromagnetic waves emitted by a charged particle crossing an interface between media is investigated. It is shown that the volume-wave radiation field arises not only as a result of the jump in the dielectric constant at the boundary but also as a result of the velocity jump and the reflection of an electron induced by the presence of a nonuniform potential barrier. The angular distribution of the transition radiation intensity is obtained. Zh. Tekh. Fiz. 68, 11–14 (January 1998)     

Special features of the angular distribution of synchrotron radiation power of descrete spectral harmonics

A review of new achievements in theoretical investigations of angular distribution of synchrotron radiation power is presented. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 5–19, April, 2008.     

Nature of the microwave response of a YBaCuO Josephson junction on a bicrystalline substrate

The response of YBaCuO Josephson junctions on a bicrystalline substrate to the action of microwave radiation is found to contain, besides the Josephson response, a contribution associated with the tunneling of quasiparticles through channels formed by localized states in the region of the Josephson junction. It is shown that this contribution is associated with an increase in the conduction through these channels under the action of the radiation on the junction. Pis’ma Zh. éksp. Teor. Fiz. 64, No. 6, 416–420 (25 September 1996)     

An integrated optical system for the vacuum ultraviolet region

We use a 0.5 m Seya-Namioka monochromator and two gold plated cylindrical mirrors to set up an optical system which produces a collimated beam of plane polarized, monochromatic radiation in the vacuum ultraviolet region. The two mirrors compensate for the astigmatism of the Seya-Namioka monochromator, thereby increasing the spectral resolution drastically. The degree of linear polarization is about 0.97–1.00 in the spectral region of 6–11.5 eV.     

Excitation of the hydrogen subsystem in metals and alloys by ionizing radiation

Models of nonequilibrium-stimulated diffusion and the release of hydrogen and its isotopes from metals by the action of ionizing radiation are considered. It is suggested that the acceleration of the release of hydrogen from metals by the action of radiation is due to the excitation of nonequilibrium vibrational states in the hydrogen subsystem of the metals and a reduction in the surface potential barrier by the desorbing molecules. It is shown, in particular, that the diffusion coefficient of deuterium in Pd is increased by a factor of 30 by the action of radiation compared with a nonirradiated sample. Tomsk Polytechnical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 3–10, November, 1998.     

The Chern–Simons term induced at high temperature and the quantization of its coefficient

By perturbative calculations of the high-temperature ground-state axial vector current of fermion fields coupled to gauge fields, an anomalous Chern–Simons topological mass term is induced in the three-dimensional effective action. The anomaly in three dimensions appears just in the ground-state current rather than in the divergence of ground-state current. In the Abelian case, the contribution comes only from the vacuum polarization graph, whereas in the non-Abelian case, contributions come from the vacuum polarization graph and the two triangle graphs. The relation between the quantization of the Chern–Simons coefficient and the Dirac quantization condition of magnetic charge is also obtained. It implies that in a (2+1)-dimensional QED with the Chern–Simons topological mass term and a magnetic monopole with magnetic charge g present, the Chern–Simons coefficient must be also quantized, just as in the non-Abelian case. Received: 7 April 1999 / Published online: 3 November 1999     

Method of kinematic projecting of pulsar-emission profiles

A method for constructing profiles of incoherent pulsar emission based on the instantaneous angular phase distribution function of radiant power emitted by a relativistic source that moves in the magnetosphere of a neutron star is suggested. In general, this phase function depends on the kinematic parameters of the radiation source (its velocity and acceleration) and on the direction of radiation emission with respect to the rotating neutron star (the observation direction). The method is illustrated by the example of calculated profiles of fan pulsar radiation with the use of the phase function of synchrotron radiation. It is stated that his method can easily be generalized for other types of relativistic radiation. Tomsk State University; Tomsk State Pedagogical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 26–31, January, 2000.