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We study theoretically the Vavilov-Čerenkov radiation from a nonrelativistic electron bunch moving in free space over a left-handed
medium. It is shown that in the frequency range in which the refractive index of the medium is negative, Vavilov-Čerenkov
radiation leads to simultaneous excitation of volume and surface electromagnetic waves in the same frequency range. The wave
vector of the surface wave in the plane of an interface of two media is greater in magnitude than the corresponding quantity
for the volume wave. The energy fluxes of volume and surface waves in the left-handed medium are studied. The radiation pattern
of the bunch is found.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 5, pp. 406–417, May 2007. 相似文献
2.
E. I. Averkov 《Journal of Applied Spectroscopy》1988,48(3):294-297
Translated from Zhurnal Prikladnoi Spektroskopii, Vo. 48, No. 3, pp. 425–529, March, 1988. 相似文献
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Excitation of potential surface waves by a nonrelativistic electron beam traveling in a vacuum space near the boundary of
a layered superconductor is studied theoretically. Dispersion relations for surface waves at an arbitrary angle between superconductor
layers and interface are obtained. Allowance is made for an arbitrary direction of wave propagation in the interfacial plane.
Increments of kinetic and hydrodynamic instabilities are found. It is shown that absolute instability may occur. 相似文献
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The possibility of using the transition radiation of an electron bunch to generate nonstationary anharmonic pulses in free space and in a dispersive medium is demonstrated. It is shown that the transition radiation of the bunch gives rise to an infinite train of nonstationary anharmonic pulses described by solutions to the Klein-Gordon equation. The polarization of the resulting field at its leading edge appears to be different from the field polarization at the interface. The leading edge becomes steeper with time. It is shown that the bunch density longitudinal distribution and the parameters of the dispersive medium can be determined from the values of the fields and their derivatives near the leading edge of the resulting signal. 相似文献
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Technical Physics - Dispersion properties of eigenwaves of an anisotropic cylindrical solid-state waveguide without frequency dispersion in permittivity tensor components have been analyzed... 相似文献
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Mathematical Programming - For a set X of integer points in a polyhedron, the smallest number of facets of any polyhedron whose set of integer points coincides with X is called the... 相似文献
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For each dimension d, d-dimensional integral simplices with exactly one interior integral point have bounded volume. This was first shown by Hensley. Explicit volume bounds were determined by Hensley, Lagarias and Ziegler, Pikhurko, and Averkov. In this paper we determine the exact upper volume bound for such simplices and characterize the volume-maximizing simplices. We also determine the sharp upper bound on the coefficient of asymmetry of an integral polytope with a single interior integral point. This result confirms a conjecture of Hensley from 1983. Moreover, for an integral simplex with precisely one interior integral point, we give bounds on the volumes of its faces, the barycentric coordinates of the interior integral point and its number of integral points. Furthermore, we prove a bound on the lattice diameter of integral polytopes with a fixed number of interior integral points. The presented results have applications in toric geometry and in integer optimization. 相似文献
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