Quantum Cherenkov radiation at the relative sliding of two transparent plates

Quantum Cherenkov radiation and quantum friction at the relative sliding of two transparent plates with the refractive index n have been studied in a fully relativistic theory. Radiation appears at velocities above the threshold value, v > v _c = 2nc/(n ² + 1). The contribution from s-polarized electromagnetic waves dominates near the threshold velocity. However, in the ultrarelativistic case (v → c), contributions from both polarizations are much larger than those in a nonrelativistic theory and a new contribution from the mixing of waves with different polarizations appears. The numerical results are supplemented by analytical calculations near the threshold velocity and the speed of light.     

Quantum regime for dielectric Cherenkov radiation and graphene surface plasmons

In this article, we propose a quantum regime for Cherenkov free-electron laser (CFEL) and surface plasmon polaritons (SPPs) excited in dielectric and multilayer graphene waveguides, respectively. This quantum regime is realized when the momentum spread induced in the interaction is smaller than the photon recoil. The discrete momentum exchange characterizing this interaction yields a significantly narrow single emission line. To determine the condition of the quantum regime, we derive an expression for the gain in the Cherenkov effect using a quantum mechanical treatment. It is assumed that the effective spread in momentum is due to the finite interaction length L (or the propagation length in the case of SPPs). For both cases, CFEL and SPPs, the effects of electron beam and waveguide parameters on the possibility of the quantum regime are studied. We conclude that the quantum regime can be basically verified at low electron beam energy (<40 keV) and at emission wavelengths in the near infrared range (<5 μm) when L is in the order of millimeters. In the case of SPPs, we also show that the feasibility to realize quantum SPPs is enhanced by increasing the chemical potential and number of graphene layers.     

Cherenkov radiation of a spinning particle

We consider the Cherenkov radiation of a neutral particle with magnetic moment, and the spin-dependent contribution to the Cherenkov radiation of a charged spinning particle. The corresponding radiation intensity is obtained for an arbitrary value of spin and for an arbitrary spin orientation with respect to velocity. The article is published in the original.     

填充等离子体的介质同轴波导中的切伦科夫辐射

 利用自洽线性场理论，导出了薄环形相对论电子注通过填充等离子体的介质同轴波导中的注波互作用色散方程，得到了注波互作用产生切伦科夫辐射的同步条件和波增长率。分析了填充等离子体后的波与电子注之间的能量交换及等离子体密度对色散特性、波增长率和注波能量交换的影响。分析结果表明：切伦科夫辐射是由沿介质同轴波导传播的慢波与沿薄环形相对论电子注传播的负能空间电荷波耦合所致，且其耦合强度与电子注的密度成正比；输出频率和波增长率随着填充等离子体密度的增大而提高；保持一定的输出频率，增大电子注的束流可得到高的微波输出功率。     

On the polarization characteristics of Cherenkov radiation from a dielectric screen

The Cherenkov effect is a well-known phenomenon and its properties are widely used in many fields of physics. However, some features of the polarization characteristics of Cherenkov radiation that appears when charged particles pass near azimuthally asymmetric, finite dielectric targets are still poorly studied. This problem is solved in this work. The polarization characteristics of Cherenkov radiation in the case of a rectangular dielectric screen are analyzed using the Stokes approach. Owing to the azimuthal asymmetry of the target, radiation acquires an elliptic polarization whose rotation direction and inclination angle depend both on the direction of radiation propagation and on the dielectric properties of a substance. The results demonstrate that the Cherenkov effect can be used to create sources of elliptically polarized radiation with the controlled direction of polarization rotation.     

Detection of diffraction radiation in a dielectric target simultaneously with Cherenkov radiation

The effect of the simultaneous generation of Cherenkov radiation and diffraction radiation in a dielectric target by electrons that pass near it has been experimentally studied. It has been shown that diffraction radiation appears at the upstream edge of the dielectric target, propagates inside the target, and is refracted at the down-stream edge as a beam of real photons.     

Cherenkov radiation emitted by a vortex into an anisotropic dielectric

The fields produced by a Josephson vortex moving in a sandwich placed into an anisotropic dielectric are investigated. When the vortex velocity exceeds the velocity of light in the direction of the normal to the sandwich surface, Cherenkov emission of electromagnetic waves propagating from the sandwich to the bulk of the dielectric takes place. The Poynting vector of outgoing waves is determined. It is shown that the radiation directivity considerably depends on the degree of anisotropy in the permittivity. The radiation loss power of the vortex is determined, and the relation between the transport current and the vortex velocity is established.     

Absorption of intense radiation in a transparent dielectric containing impurities

The dynamics of the process of heating a transparent dielectric medium surrounding a strongly absorbing microimpurity in an intense radiation flux are theoretically considered. It is shown that the size of the region of nonlinear absorption in the dielectric near the microimpurity increases with time no more rapidly than t. A formula is obtained for determination of the threshold intensity which satisfies the criterion of destruction of the surface layer of a solid dielectric.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 90–95, June, 1978.In conclusion, the authors express their thanks to A. M. Bonch-Bruevich for his evaluation of the results obtained.     

Cherenkov radiation by the charged particle moving in moving Hermitian medium

Detailed theoretical investigation and computer calculations on the Cherenkov radiation (CR) in moving Hermitian medium (CRMH) are presented in this paper. It has been found that, similar to that in stationary Hermitian medium (CRH) case, there are two modes in the CRMH; in general, only one of them is radiative mode, another one is local field, and the comparison of the two modes is given in the paper. The small absorption of CRMH mainly results in the Gaussian-like field intensity pattern. And the group velocity in the CRMH is always slower than the phase velocity in the moving HM, so the fine inner structure occurs. Comparing the behaviors of CRMH and CRH, we have found that the movement of the Hermitian medium (HM) brings significant influences on the CR, so there are some interesting characteristics of CRMH, such as in the CRMH; the radiation power of the “o” mode is much higher than that of “e” mode. And because of the relativistic Doppler effect, the frequency region where both modes are radiative becomes quite different from that for CRH.     

Cherenkov radiation of a Josephson vortex moving in a sandwich embedded in a dielectric medium

A motion of a Josephson vortex in a long sandwich embedded in a dielectric medium is described. If the velocity of the vortex is greater than the velocity of light in the dielectric, terahertz-band Cherenkov radiation is generated and emitted from the lateral surface of the sandwich. The radiation loss power is determined. In the case when radiation loss is compensated for by the energy gain due to transport current, a relation between the current and the velocity of the vortex is obtained.     

Simulation of propagating EAS Cherenkov radiation over the ocean surface

We present computing results of the Cherenkov light propagation in the air and water from an extensive air shower (EAS) over the ocean. Limits on the zenith angles of the showers, for which the registration of the flash of reflected photons by the space-detector is possible, are analyzed with consideration for waves on the ocean surface.     

Variation in linear susceptibility tensor at crystal surface probed by linear Cherenkov radiation

At the surfaces of crystals, linear susceptibility tensors would differ from their counterparts in the interior of the bulk crystal. However, this phenomenon has not been shown in a visible way yet. In previous researches, numerous types of nonlinear Cherenkov radiation based on different materials have been studied, while linear Cherenkov radiation is barely reported. We experimentally prove the generation of linear Cherenkov radiation on the potassium dihydrogen phosphate(KDP) crystal surface and theoretically analyze its phase-matching scheme. In our study, o-polarized light and e-polarized light can mutually convert through the linear Cherenkov process. According to this result, we figure out new nonzero elements at off-diagonal positions in the linear susceptibility tensor matrix at crystal surfaces, compared with the normal form of a bulk KDP.     

On the motion of a charged particle with radiation reaction

The object of this paper is to show that initial acceleration is uniquely determined by the condition that the physical solutions of the Dirac-Lorentz equation are regular at 2e ²/3mc ³=0. The method for obtaining this initial acceleration in the general case is given.     

Coaxial configuration of the dielectric Cherenkov maser

The linearized Lorentz force, continuity equation, and Maxwell's equations are used to calculate the system dispersion relation for a coaxial configuration of the dielectric Cherenkov maser. The system consists of two coaxial conductors lined with dielectric and an annular relativistic electron beam, which propagates between the two liners. The dispersion relation for the beam and dielectric-lined coaxial waveguide structure and the no-beam system that describes the dependence of the generated frequency on the coaxial waveguide parameters are presented. Using the linearized dispersion relation, the growth rate for the beam-TM_0n waveguide mode instability is calculated in the strong-coupling tenuous beam limit     

Quantum theory of Vavilov-Cerenkov radiation by Dirac particles in a transparent uniaxial crystal

The quantum theory of Vavilov-Cerenkov radiation by Dirac particles in a transparent uniaxial crystal is discussed. The case, in which a particle is initially moving along the crystal optical axis or perpendicular to it, is investigated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 7, pp. 100–104, July, 1971.In conclusion the authors are grateful to Professor A. A. Sokolov for his attention and interest in this work.     

Quantum particle confined to a thin-layer volume: Non-uniform convergence toward the curved surface

We clearly refine the fundamental framework of the thin-layer quantization procedure, and further develop the procedure by taking the proper terms of degree one in q₃$q_3$ (q₃$q_3$ denotes the curvilinear coordinate variable perpendicular to curved surface) back into the surface quantum equation. The well-known geometric potential and kinetic term are modified by the surface thickness. Applying the developed formalism to a toroidal system obtains the modification for the kinetic term and the modified geometric potential including the influence of the surface thickness.     

Simulating the motion of a quantum particle at constant temperature

The extended system method of Nosé and Hoover for the control of temperature of a classical ensemble if applied to the de Broglie-Bohm-Vigier formulation of quantum mechanics. This allows for the simulation of the motion of a quantum particle at a constant preset temperature. A specific algorithm for numerical solution of the resulting equations of motion, based on the application of the methods of molecular dynamics simulation, is provided.     

Electromagnetic radiation of a neutral fermi particle moving in an external field

The neutral particle has an anomalous magnetic moment; the motion in constant and homogeneous electric and magnetic fields is discussed. Photons can be emitted; the polarization is examined. It is shown that the emission is related to spin rotation.