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1.
A relativistic expression has been obtained for the curvature of trajectory of the wave vector of an electromagnetic wave in a moving optically transparent medium. It has been shown that the curvature of the trajectory and angular deviation of rays appear in a homogeneous isotropic medium if the gradient of the velocity field in the medium is nonzero. The bending of the trajectory in the medium with the velocity gradient is a firstorder effect in the ratio u/c. 相似文献
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Dispersion and energy characteristics of slow volume electromagnetic waves in tangentially magnetized ferromagnetic films are computed in a rigorous manner. For a wave that experiences anomalous dispersion and propagates with the external magnetostatic field, distinguishing features of the energy-flux velocity and the ratio of the electric to the magnetic energy density as functions of the wave number are noted. A marked contrast between these results and those obtained within the magnetostatic approximation is revealed for a wide range of wave numbers. 相似文献
4.
It is shown that due to the relativistic transformation law of angles, a laser pulse reflected from a moving retroreflector propagates not strictly back, but at a small angle to the direction of the laser station. For this reason, the ray located on the periphery of a pulse reaches the receiving telescope of the laser station instead of the central ray of a pulse. As a result, the flux of electromagnetic energy received by the laser station is certainly less than the flux of energy in the vicinity of the central ray. The energy flux attenuation coefficient is assessed on the basis of numerical analysis. It is shown that if the receiving telescope is separated from the laser station in order to be mobile and is moving along the Earth’s surface so that the center of each spot formed by a pulse of the reflected light hits the telescope, then the electromagnetic energy flux during laser probing of the satellite will be higher by more than 100 times in comparison with the energy flux received by the stationary telescope of the laser station. From our study it follows that the maximum speed of motion of the centers of spots on the Earth’s surface does not exceed 8 km/h. 相似文献
5.
We consider the radiation from nonoscillating dipoles traveling with constant velocity directed parallel or antiparallel to
the velocity of a homogeneous transparent moving medium. It is assumed that the medium in its rest frame is isotropic and
has no spatial dispersion. We obtain expressions for the radiative energy losses and estimate the polarization energy losses
of electric and magnetic dipoles of different orientations. In particular, it is shown that the energy loss of a source is
negative if it moves in the direction of the medium motion and the source velocity is less than the medium velocity. Estimates
for the energy losses of dipoles in the cases of an electron beam and a flow of a weakly dispersive medium are given.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 6, pp. 502–512, June 2006. 相似文献
6.
A. Shevchenko 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2012,66(6):1-12
Electromagnetic angular momentum describes the ability of electromagnetic field to impose torque on matter. We show that for an electromagnetic field ?C such as an optical beam field ?C in a medium, the torque density is determined by two fundamental quantities: the angular momentum flux tensor and the angular momentum density of the field. It is remarkable that the tensor alone gives the full picture of the angular momentum transfer between the field and the medium in all stationary electromagnetic phenomena. We derive a general expression for this tensor and apply the theory to several important examples without resorting to the classical paraxial approximation. 相似文献
7.
We consider the radiation from oscillating electric and magnetic dipoles moving with constant velocity directed parallel or
antiparallel to the velocity of the surrounding medium. It is assumed that the medium in its rest frame is isotropic and has
no spatial dispersion. We obtain expressions for the spectral density of the radiated power. In the case of a nondispersive
medium, algebraic expressions for the total radiated power in the regime of “subluminal relative motion” are also obtained.
In particular, it is shown that the energy loss of a source is negative if it moves in the direction of the superluminal motion
of the medium and the source velocity is somewhat smaller than the medium velocity. It is noted that this phenomenon takes
place for a smaller difference between the velocities of the source and the medium compared with a similar phenomenon for
nonoscillating sources.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 4, pp. 316–328, May 2007. 相似文献
8.
We study radiation fields of various dipole sources as well as of a source of bisphere type moving in a nondispersive medium with velocity less than the speed of light in this medium. In particular, it is shown that in certain cases, there is a displacement of the angular pattern of a source in the direction opposite to the medium flow. Expressions for energy losses of the considered sources are obtained. It is pointed out that the radiation power of both a bisphere and a toroidal dipole increases with increasing velocity of motion of the medium more rapidly compared with the ordinary dipoles. 相似文献
9.
The electromagnetic radiation produced by the single moving Josephson vortex in the inhomogeneous junction has been theoretically considered. The radiation is shown to appear at the definite threshold vortex velocity. The expressions for the energy flux and the radiation frequency have been found. 相似文献
10.
I. P. Lokhtin S. V. Petrushanko L. I. Sarycheva A. M. Snigirev 《Physics of Atomic Nuclei》2006,69(9):1609-1621
Measurement of angular correlations between energy fluxes is one of the promising methods for analyzing the structure of events in ultrarelativistic heavy-ion collisions. The possibility of diagnosing the rescattering and the energy loss of hard partons in dense QCD matter is studied here on the basis of an analysis of the transverse-energy correlation function. It is shown that, if events are chosen for an analysis in a special way (that is, if at least one jet is required to have a transverse energy above some threshold) and if the procedure of background subtraction is applied in each event, the energy correlation function is sensitive to the parton energy loss and the angular spectrum of gluons emitted in a medium. The transverse-energy correlation function calculated for all events reflects the global structure of the transverse energy flux: it is independent of the azimuthal anisotropy of the energy flux for central collisions and is sensitive to the azimuthal anisotropy of the energy flux, reproducing all of its Fourier harmonics for noncentral collisions, but the coefficients of these harmonics are squared. A special correlation function in the vicinity of the maximum energy deposition in each event makes it possible to study changes in the jet shape. Within the conventional scenario of the scattering of hard jet partons on accompanying medium constituents, the correlation function is independent of the rapidity position of the jet axis and becomes much broader (symmetrically in the rapidity and azimuthal angle) than in proton-proton collisions. In the case of scattering on slow medium constituents, the broadening of the correlation function depends on the rapidity position of the jet axis and, in relation to the preceding scenario, increases sizably for jets of rather high rapidity. 相似文献
11.
《Physics letters. A》2001,292(3):166-172
A set of exact quasi-local conservation equations is derived from the Einstein's equations using the first-order Kaluza–Klein formalism of general relativity in the (2,2)-splitting of 4-dimensional spacetime. These equations are interpreted as quasi-local energy, momentum, and angular momentum conservation equations. In the asymptotic region of asymptotically flat spacetimes, it is shown that the quasi-local energy and energy-flux integral reduce to the Bondi energy and energy-flux, respectively. In spherically symmetric spacetimes, the quasi-local energy becomes the Misner–Sharp energy. Moreover, on the event horizon of a general dynamical black hole, the quasi-local energy conservation equation coincides with the conservation equation studied by Thorne et al. We discuss the remaining quasi-local conservation equations briefly. 相似文献
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It is shown that the generally accepted definition of the Poynting vector and the energy flux vector defined by means of the energy density of the electromagnetic field (Umov vector) lead to the prediction of the different results touching electromagnetic energy flux. The experiment shows that within the framework of the mentioned generally accepted definitions the Poynting vector adequately describes the electromagnetic energy flux unlike the Umov vector. Therefore one can conclude that a generally accepted definitions of the electromagnetic energy density and the Poynting vector, in general, are not always compatible. 相似文献
14.
In a recent paper a new theory of radiative energy transfer in free electromagnetic fields was formulated. The basic quantities in this theory are the so-called angular components of the average electromagnetic energy density and of the average Poynting vector. In the present paper it is shown that these angular components obey differential equations that may be considered to be rigorous equations for the radiative transfer of energy and of momentum in free electromagnetic fields. 相似文献
15.
Edward Witten 《Annals of Physics》1979,120(1):72-81
We consider the behavior of a slowly moving classical point particle in a magnetic field in two dimensions, and show that, although energy conservation would permit the particle to escape to infinity, it in fact does not escape but is permanently trapped in the field. For any given magnetic field, this is true for particles of slow enough velocity. For such motion the magnetic flux enclosed by the Larmor orbits is an adiabatic invariant. Our results may be described by saying the deviations from conservation of this invariant are not cumulative but remain bounded over arbitrary time intervals, and are small if the velocity is small. 相似文献
16.
The electromagnetic radiation of a charge moving in an infinite 3D structure made of parallel wires is considered. The periods of the structure are assumed to be small; therefore, it can be described by an effective permittivity tensor. The charge velocity is perpendicular to the wires. Analytical and numerical investigations are performed, and some unusual properties of the radiation are noted. It is shown that the radiation propagates along the wires and concentrates near certain rays behind the charge. The wave field does not vary with distance from the charge along these rays (if energy loss in the medium is negligible). The prospects for the use of the structure under consideration for diagnostics of bunches are noted. 相似文献
17.
P. K. Shukla L. Stenflo R. Bingham H. A. Bethe J. M. Dawson J. T. Mendon a 《Physics letters. A》1997,230(5-6):353-357
The nonlinear propagation of an intense neutrino flux in an electron-positron plasma with equilibrium density and magnetic field inhomogeneities is considered. It is found that the neutrinos are nonlinearly coupled with electrostatic and electromagnetic disturbances due to weak Fermi interaction and ponderomotive forces. The process is governed by a Klein-Gordon equation for the neutrino flux and a wave equation for the plasma oscillations in the presence of the ponderomotive force of the neutrinos. This pair of equations is then used to derive a nonlinear dispersion relation which exhibits that nonthermal electrostatic and electromagnetic fluctuations are created on account of the energy density of the neutrinos. The relevance of our investigation to the anomalous absorption of neutrinos in a nonuniform magnetized medium is pointed out. 相似文献
18.
G Whitworth 《The Journal of the Acoustical Society of America》1990,88(4):1960-1963
Acoustic streaming theory is derived that is applicable to a fluid that is slow moving in a reference frame that rotates with a constant angular velocity omega. A simplified streaming equation is obtained for the special case in which the acoustic angular frequency omega is large relative to omega, and the change in fluid density due to rotation alone is negligible. For this special case it is shown that the "driving force" for the acoustic streaming is independent of omega. Thus, if no acoustic streaming is present in a fluid system that is stationary, then no steady-state acoustic streaming is predicted for a similar system that rotates with constant angular velocity. For a system in which acoustic streaming is present, the flow behavior depends on the relative magnitudes of the Coriolis forces and the viscous forces. If the Ekman number is large (that is, the viscous force dominates) then the predicted flow is identical to that which would exist in a stationary system. If, on the other hand, the Ekman number is small then the Coriolis force dominates and the component of flow in the direction of the axis of rotation can be much smaller in the rotating system than in a similar system at rest. 相似文献
19.
Xiaochang Ni K. K. Anoop X. Wang D. Paparo S. Amoruso R. Bruzzese 《Applied Physics A: Materials Science & Processing》2014,117(1):111-115
We investigated the ion laser-produced plasma plume generated during ultrafast laser ablation of copper and silicon targets in high vacuum. The ablation plasma was induced by ≈50 fs, 800 nm Ti:Sa laser pulses irradiating the target surface at an angle of 45°. An ion probe was used to investigate the time-of-flight profiles of the emitted ions in a laser fluence range from the ablation threshold up to ≈10 J/cm2. The angular distribution of the ion flux and average velocity of the produced ions were studied by moving the ion probe on a circle around the ablation spot. The angular distribution of the ion flux is well described by an adiabatic and isentropic model of expansion of a plume produced by laser ablation of solid targets. The angular distribution of the ion flux narrows as the laser pulse fluence increases. Moreover, the ion average velocity reaches values of several tens of km/s, evidencing the presence of ions with kinetic energy of several hundred eV. Finally, the ion flux energy is confined in a narrow angular region around the target normal. 相似文献
20.
Pablo L. Saldanha 《Optics Communications》2011,284(12):2653-2657
We defend a natural division of the energy density, energy flux and momentum density of electromagnetic waves in linear media in electromagnetic and material parts. In this division, the electromagnetic part of these quantities have the same form as in vacuum when written in terms of the macroscopic electric and magnetic fields, the material momentum is calculated directly from the Lorentz force that acts on the charges of the medium, the material energy is the sum of the kinetic and potential energies of the charges of the medium and the material energy flux results from the interaction of the electric field with the magnetized medium. We present reasonable models for linear dispersive non-absorptive dielectric and magnetic media that agree with this division. We also argue that the electromagnetic momentum of our division can be associated with the electromagnetic relativistic momentum, inspired on the recent work of Barnett [Phys. Rev. Lett. 104 (2010) 070401] that showed that the Abraham momentum is associated with the kinetic momentum and the Minkowski momentum is associated with the canonical momentum. 相似文献