THz Coherent Vavilov-Cherenkov Radiation in a Special Three-Mirror Cavity

In the modern science and technology a compact and having enough output power terahertz radiation source working in room temperature have earned great attention. This paper is devoted to utilize electron bunches stimulate Vavilov-Cherenkov Radiation (VCR) in a special three-mirror quasi-optical cavity to generate coherent THz waves. This novel three-mirror quasi-optical resonant cavity has the coaxial field pattern which enables field establish in this cavity effectively. The analytical theory of the radiation exited by a train of electron bunches in the special kind of three-mirror cavity has been carried out and the coherent VCR has been achieved by the computer simulation. All those shows that this method can be used to establish useful THz radiation source by the normal electron gun and the commonly used microwave devices.     

Vavilov–Cherenkov radiation when cosmic rays pass through the relic photon gas and when fast charged particles traverse an optical laser beam

Using a new [9, 10] quantum theory of Vavilov–Cherenkov radiation (VCR) based on Abraham’s theory, we show that a threshold VCR effect can be excited by the relic photon gas when relativistic charged cosmic-ray particles with γ ≥ γ_th ≈ 1.9 × 10¹⁰ (where γ^–2 = 1–v²/c², v is the particle speed, and c is the speed of light in a vacuum) pass through it. This is compatible with the well-known GZK cutoff [7, 8] at γ ≈ 10¹¹. We have obtained the condition γ > γ_th ≈ 2.1 × 10² for the appearance of VCR when a sufficiently fast charged particle (an electron, a proton, or a nucleus) passes through intense laser radiation. This condition ensures that VCR can be observed experimentally (e.g., on the Large Hadron Collider) without invoking any additional conditions required from the currently existing estimate of γth > 8.8 × 10⁴ [13] based on the now universally accepted quantum theory of VCR, which follows from Minkowski’s theory (and which gives an estimate of γ > 10²¹ when excited by the relic photon gas).     

Spectral and Amplitude–Time Characteristics of the Cherenkov Radiation upon Excitation of Transparent Materials by an Electron Beam

Optics and Spectroscopy - The interest in studying characteristics of the Vavilov–Cherenkov radiation (VCR) increased in connection with works on creation of runaway electron (RE) detectors...     

Vavilov–Cherenkov Radiation in an Inclined Dielectric Plate and Violation of Azimuthal Symmetry

Physics of Particles and Nuclei Letters - For over half a century, Vavilov–Cherenkov radiation (VCR) has been used for detecting elementary particles. Lately, some authors have proposed using...     

Absence of Cherenkov properties of coherent radio emission from atmospheric showers at frequencies below 100 MHz

In many modern papers devoted to the calculation of radio emissions from extensive atmospheric showers (EASs) in the 10–100 MHz range, the radiation from EASs of charged particles moving with a velocity higher than the speed of light in air is identified as Vavilov—Cherenkov radiation (VCR). In this paper it is shown that radio emissions from EASs at frequencies less than 100 MHz do not possess the properties of VCR recorded from EASs in the optical range. Original Russian Text ? N.N. Kalmykov, A.A. Konstantinov, 2009, published in Vestnik Moskovskogo Universiteta. Fizika, 2009, No. 3, pp. 99–102.     

双波长分光光度法同时测定载硫酸长春新碱/姜黄素聚合物纳米粒中两种药物的含量

以聚乙二醇单甲醚-聚乳酸-乙醇酸共聚物（m PEG-PLGA）为载体材料,制备同时载带硫酸长春新碱（VCR）和与之具有协同抗肿瘤作用的姜黄素（Cur）的m PEG-PLGA纳米粒（VCR/Cur-m PEG-PLGA-NP）。建立了以等吸收双波长紫外分光光度法同时测定纳米粒中VCR和Cur含量的方法,研究显示,VCR测定波长296.5nm,等吸收波长462nm;Cur测定波长414nm;VCR在4.0—36.0μg.mL-1范围内,浓度C与差值吸光度ΔA呈良好线性相关;Cur在0.5—8.0μg.mL-1范围内,浓度C与吸光度A具有良好的线性关系。该方法简便迅速,结果准确可靠,适用于VCR/Cur-m PEG-PLGA-NP中药物含量的同时测定。     

On the theory of diffraction radiation

A macroscopic theory of diffraction radiation emerging when a charged point particle moves in the vicinity of a perfectly conducting screen is developed. The integral equations derived for radiation fields form the basis for analyzing the similarity and difference of diffraction of electromagnetic radiation and diffraction radiation from a charged particle. It is shown that in the case considered here, the widely used model in which the radiation field can be represented as the field of surface current has more stringent limits of application as compared to the classical theory of diffraction. This considerably restricts the applicability of the results obtained earlier using the double-layer method to only ultrarelativistic energies and to transit angles of particles close to the direction of the normal to the screen surface. The method developed here is used for analyzing familiar problems of diffraction radiation, such as radiation emerging during normal transit of a particle along the axis of a circular aperture in the screen, radiation emitted during oblique transit near a perfectly conducting half-plane, and radiation emitted during oblique transit of a particle through a rectangular slit in an infinitely large screen. In the latter case, the results obtained after the limiting transition to zero width of the slit completely coincide with the theory of transition radiation for arbitrary energies of the particle and its angle of incidence to the screen.     

Influence of the polarisation of the medium on the radiation of channeled particles

The theory of the electromagnetic radiation from channeled particles is developed with inclusion of a virtual photon interaction with the crystal. Simple estimates are made for the spectral and angular distribution of the radiation. It is shown that the polarisation of the medium may lead to a drastic shrinking of the frequency range allowed for the radiation. The possibility of an increase of the transverse energy of a particle caused by radiation is predicted.     

A new approach to the theory of Cherenkov radiation based on relativistic generalization of the Landau criterion

Relativistic generalization of the Landau criterion is obtained which, in contrast to the classical Tamm-Frank and Ginzburg theories, determines the primary energy mechanism of emission of nonbremsstrahlung Cherenkov radiation. It is shown that Cherenkov radiation may correspond to a threshold energetically favorable conversion of the condensate (ultimately long-wavelength) elementary Bose perturbations of a medium into transverse Cherenkov photons emitted by the medium proper during its interaction with a sufficiently fast charged particle. The threshold conditions of emission are determined for a medium with an arbitrary refractive index n, including the case of isotropic plasma with n<1 for which the classical theory of Cherenkov radiation prohibits such direct and effective nonbremsstrahlung emission of these particular transverse high-frequency electromagnetic waves. It is established that these conditions of emission agree with the data of well-known experiments on the threshold for observation of Cherenkov radiation, whereas the classical theory only corresponds to the conditions of observation of the interference maximum of this radiation. The possibility of direct effective emission of nonbremsstrahlung Cherenkov radiation, not taken into account in the classical theory, is considered for many observed astrophysical phenomena (type III solar radio bursts, particle acceleration by radiation, etc.).     

Modeling of the laser and lamp treatment of telangiectasia

The effects of monochromatic and polychromatic radiation on human skin and veins are modeled on the basis of the theory of radiation transfer and the theory of heat conduction. Using the criteria of safety and efficiency of treatment, conclusions regarding the optimal parameters of sources of radiation are drawn.     

Semi-classical approximation and the problem of boundary conditions in the theory of relativistic particle radiation

Abstract

The process of relativistic particle radiation in an external field has been studied in the semi-classical approximation rather extensively. The main problem arising in the studies is to express the formula of the quantum theory of radiation in terms of classical quantities, for example of the classical trajectories. However, it still remains unclear how the particle trajectory is assigned, that is which particular initial or boundary conditions determine the trajectory in semi-classical approximation quantum theory of radiation.

We shall try to solve this problem. Its importance comes from the fact that in some cases one and the same boundary conditions may give rise to two or more trajectories. We demonstrate that this fact must necessarily be taken into account on deriving the classical limit for the formulae of the quantum theory of radiation, since it leads to a specific interference effect in radiation.

The method we used to deal with the problem is similar to the method employed by Fock to analyze the problem of a canonical transformation in classical and quantum mechanics.     

Quantum deformation of the angular distributions of synchrotron radiation. Emission from particles in the first excited state

The exact expressions for the characteristics of synchrotron radiation of charged particles in the first excited state are obtained in analytical form using quantum theory methods. We performed a detailed analysis of the angular distribution structure of radiation power and its polarization for particles with spin 0 and 1/2. It is shown that the exact quantum calculations lead to results that differ substantially from the predictions of classical theory.     

Generalized surface current method in the macroscopic theory of diffraction radiation

The surface current method known in the theory of electromagnetic waves diffraction has been generalized to be applied to the problems of diffraction radiation generated by a charged particle moving nearby an ideally-conducting screen in vacuum. An expression for induced surface current density leading to the exact results in the theory of transition radiation has been derived, and by using this expression several exact solutions of diffraction radiation problems are found. Limits of applicability for the earlier known models based on the surface current conception are indicated. Properties of radiation from a semi-plane and from a slit in cylinder are investigated at the various distances to observer.     

On the eikonal approximation in the theory of transition radiation

The transition radiation of relativistic electrons in nonuniform media is considered. Based on the equivalent photon method and the eikonal approximation in wave mechanics, a method for describing this process is proposed. For the case in which the permittivity depends on several coordinates, equations for the spectral-angular density of transition radiation are obtained. The main results obtained in the Born and eikonal approximations of the theory of transition radiation are compared. The equations obtained are used to analyze the transition radiation process for a fiberlike target.     

An application of the stationary-phase method to the analysis of complex systems

The equation describing the points of stationary phase for the integral representing the vector potential gives the conditions of existence and limits of regions of locally coherent radiation. The equation is applied to Cherenkov radiation and to the theory of conical spiral antennas.     

The Hertz Tensor as the Basis of Relativistic Sub-Electrodynamics

Russian Physics Journal - At the present time, the classical theory of radiation of charged particles is a complete theory. It has wide applications in the generation of various radiation sources:...     

A generalization of the method of enclosing surfaces in classical radiation theory

The method of enclosing surfaces in classical radiation theory is generalized to the case of a charged particle moving in a transparent isotropic dispersive medium. The synchrotron and ondulator radiation problems are discussed, and expressions are derived and analyzed for the angular-spectral distribution of the radiation power in these cases.     

Extension of the doubling method to inhomogeneous sources

This paper gives a general theory for applying the doubling method to spatially inhomogeneous radiation sources whose angular and spatial variations separate. In particular, inhomogeneous sources of thermal radiation may be efficiently treated by the methods herein, as well as direct and specularly-reflected beams of radiation which do not lie along a quadrature direction for the intensity. Doubling rules for a linear-in-optical-depth source (which may approximate a source of thermal radiation) and for an exponential-in-optical-depth source are derived as special cases.     

Scattering matrix and radiation characteristics of the junction between two different monomode microwave or optical dielectric waveguides

The elements of the scattering matrix of the junction between two circular monomode dielectric waveguides with different diameters and/or different refractive indices are calculated using the mode matching method. The theory is evaluated numerically for a wide range of parameters and simplified considerably for two important cases of weakly guiding waveguides.The radiation pattern of the junction is calculated using the Huygens-Kirchhoff theory of diffraction and shown to be reducible to the weighted difference of the radiation patterns of the ends of the primary and secondary waveguide. Simple approximations are derived for weakly guided waves.The theory is verified experimentally by measuring the scattering parameters, the far-field radiation pattern and the near-field distribution of abrupt changes in diameter of microwave dielectric rod transmission lines.