A5054663443- Crystallography and Radiation Phenomena
- Quantum Electrodynamics and Casimir Effect
- Cosmology and Gravitation Theories
- Particle Accelerators and Free-Electron Lasers
- Black Holes and Theoretical Physics
- Noncommutative and Quantum Gravity Theories
- Gyrotron and Vacuum Electronics Research
- Plasmonic and Surface Plasmon Research
- Photonic Crystals and Applications
- Relativity and Gravitational Theory
- Astrophysics and Cosmic Phenomena
- Geophysical Methods and Applications
- Advanced X-ray Imaging Techniques
- Laser-Plasma Interactions and Diagnostics
- Electromagnetic Simulation and Numerical Methods
- Ultrasonics and Acoustic Wave Propagation
- Photonic and Optical Devices
- Metamaterials and Metasurfaces Applications
- Near-Field Optical Microscopy
- Electromagnetic Scattering and Analysis
- Electromagnetic Compatibility and Measurements
Institute for Informatics and Automation Problems
2019-2023
Yerevan State University
2018-2023
Abstract We investigate the quasi-coherent radiation from a train of electron bunches moving along axis cylindrical waveguide, assuming that part waveguide is filled with dielectric medium. For permittivity latter, general case dispersion considered. It shown under certain conditions on medium and values problem parameters, modes become equidistant. As consequence, Cherenkov may be generated first several simultaneously. An example law provided for which corresponding suppressed.
We investigate the radiation of surface polaritons by a charged particle rotating around dielectric waveguide. The general case is considered when waveguide immersed in homogeneous medium. For evaluation corresponding electromagnetic fields Green tensor used. A formula derived for spectral distribution intensity surface-type modes. It shown that waves are radiated on eigenmodes cylinder. demonstrate number quanta given harmonic can be essentially larger than guiding modes geometry under...
The radiation of electromagnetic surface waves is investigated for a charged particle rotating around dielectric cylinder immersed into homogeneous medium. Formulae are provided the corresponding electric and magnetic fields intensity. It shown that radiated on eigenmodes cylindrical waveguide.
The vacuum expectation value of the current density for a charged scalar field is investigated in Rindler spacetime with part spatial dimensions compactified to torus. It assumed that prepared Fulling-Rindler state. For general values phases periodicity conditions and lengths compact dimensions, expressions are provided Hadamard function currents. along periodic magnetic flux enclosed by those vanishes on horizon. obtained results compared corresponding currents Minkowski vacuum....
We investigate the radiation from a bunch of relativistic electrons moving along cylindrical waveguide axis, assuming that is partially loaded by medium with periodic dielectric permittivity and magnetic permeability. The spectral distribution energy flux through cross section studied at large distances medium. analysis based on corresponding exact solution Maxwell equations for case single electron axis. results numerical calculations are presented in special layered consisting finite...
We investigate the radiation from a charged particle rotating around dielectric cylinder with negative real part of permittivity. For general case frequency dispersion in permittivity, expressions are derived for electric and magnetic fields angular density intensity on given harmonic. Compared positive new interesting features arise nonrelativistic limit at small angles respect to axis. Another feature is appearance sharp narrow peaks large harmonics. analytically estimate height, width...
Abstract One of the areas research conducted at Institute Applied Problems Physics (IAPP) is study influence different media on radiation processes generated by relativistic charged particles (channeling radiation, transition Cherenkov diffraction etc.). Additionally, many interesting phenomena arise when acoustic fields are excited in media. This exactly field acoustophysics. The paper devoted to review studies Lab. 3 IAPP these areas.
We investigate the radiation of surface polaritons by an annular beam that coaxially encloses a cylindrical waveguide surrounded homogeneous medium. By using Green dyadic, electromagnetic potentials and electric magnetic fields are found inside outside waveguide. The expression for energy losses is derived general case dispersion dielectric permittivities cylinder. A comprehensive analysis presented in spectral range corresponding to polaritons. highest peaks distribution obtained...
For a massive scalar field with general curvature coupling we evaluate the Wightman function in geometry of two parallel branes perpendicular to AdS boundary. On separate branes, operator is constrained by Robin boundary conditions, general, different coefficients. In region between their contribution explicitly separated. By using this decomposition, brane-induced effects on vacuum expectation values for squared and energy-momentum tensor are investigated. The behavior those studied various...
For the electromagnetic field in (D+1)-dimensional locally de Sitter (dS) spacetime, we analyze effects of a generalized cosmic string type defect on vacuum expectation value energy-momentum tensor. Bunch-Davies state, topological contributions are explicitly extracted both diagonal and off-diagonal components. The latter describes presence radially directed energy flux state. It vanishes for $D=3$ because conformal invariance is towards $D\geq 4$ . stresses anisotropic and, unlike to...
For the electromagnetic field in (D+1)-dimensional locally de Sitter (dS) spacetime, we analyze effects of a generalized cosmic string type defect on vacuum expectation value energy-momentum tensor. Bunch-Davies state, topological contributions are explicitly extracted both diagonal and off-diagonal components. The latter describes presence radially directed energy flux state. It vanishes for $D=3$ because conformal invariance is towards $D\geq 4$ . stresses anisotropic and, unlike to...
We investigate the properties of fermionic Fulling-Rindler vacuum for a massive Dirac field in general number spatial dimensions. As important local characteristics, condensate and expectation value energy-momentum tensor are evaluated. The renormalization is reduced to subtraction corresponding values Minkowski vacuum. It shown that fermion vanishes massless negative nonzero mass. Unlike case scalar fields, stresses isotropic fields. energy density pressures negative. For spectral...
We investigate the expectation value of field squared for a charged scalar in Rindler spacetime with toroidally compact dimensions. The values are compared Fulling-Rindler and Minkowski vacua. For general phases periodicity conditions on operator along dimensions, integral representations provided difference those values. vacuum is an even periodic function magnetic flux enclosed by Simple asymptotic expressions given near horizon small accelerations. show that mean smaller than respective vacuum.
We investigate the properties of fermionic Fulling-Rindler vacuum for a massive Dirac field in general number spatial dimensions. As important local characteristics, condensate and expectation value energy-momentum tensor are evaluated. The renormalization is reduced to subtraction corresponding values Minkowski vacuum. It shown that fermion vanishes massless negative nonzero mass. Unlike case scalar fields, stresses isotropic fields. energy density pressures negative. For field, spectral...
We investigate the electromagnetic radiation from a chain of relativistic charged particles uniformly rotating along equatorial orbit around dielectric ball. For weak absorption in ball material, at certain rotation frequency intensity becomes significantly higher than corresponding value for charges free space or transparent medium with same constant as that material. In case an equidistant distribution we determine values parameters problem which emit coherently. It is shown on given...
For a massive scalar field with general curvature coupling we evaluate the Wightman function in geometry of two parallel branes perpendicular to AdS boundary. On separate branes, operator is constrained by Robin boundary conditions, general, different coefficients. In region between their contribution explicitly separated. By using this decomposition, brane-induced effects on vacuum expectation values (VEVs) for squared and energy-momentum tensor are investigated. The behavior those studied...
For general number of spatial dimensions we investigate the cosmological dynamics driven by a constant and source with barotropic equation state. It is assumed that for both those sources energy density can be either positive or negative. Exact solutions equations are provided flat models. models curved space zero expressed in terms hypergeometric function. The qualitative evolution described all values state parameter. We specify parameter combinations signs matter which nonsingular. An...