ABOUT THE ACCELERATION RATE OF RELATIVISTIC BEAMS BY A SURFACE WAVE IN A DIELECTRIC LASER ACCELERATOR

An analysis of the dependence of the acceleration rate of charged particles by a surface wave arising when a la-ser pulse/(plane wave) is incident on the interface between two dielectric media on the phase velocity of the excited wave is carried out. It is shown that at resonance acceleration this dependence has a maximum, for ultra-relativistic particles the acceleration rate tends to zero. The dependences of the acceleration rate on the phase velocity of the excited wave for various refractive indices (dielectric permittivities) of optically transparent medias are investigated analytically and numerically.

Interaction of an electromagnetic E-wave with a thin conducting film between two dielectric media in the case of an anisotropic isoenergetic surface and impurity scattering

The coefficients of reflection, transmission and absorption are calculated in the framework of the kinetic approach, when an electromagnetic E-wave interacts with a thin conducting film located between two dielectric media. To account for the surface scattering of charge carriers is used a model of mirror-diffuse boundary conditions, assuming that the specularity coefficients of the upper and lower surfaces of the film differ from each other. The electromagnetic wave falls on the upper surface of the film at an arbitrary angle. The case of an anisotropic isoenergetic surface of a conductor having the form of a three-axis ellipsoid, one of the main axes of which is parallel to the magnetic field strength of the wave, and the other is perpendicular to the film surfaces, is considered. The impurity scattering of electrons (holes) is dominated in the volume of the conductor. The dependence of the absorption coefficient on the parameters of the isoenergetic surface of the conductor is analyzed.

Using Antenna Arrays with Only One Active Element for Beam Reconfiguration and Sensitive Study in Dielectric Media

Antenna array pattern reconfiguration is usually achieved by changing the relative amplitudes and/or phases of the excitation distribution present in the array, at the cost of complex feeding networks. In this work, the mechanical displacement of a parasitic array perpendicular to another array with a single driven element is proposed. Additionally, the antenna is optimized addressing the variation of its response led by changes of the environmental dielectric constant of a surrounding gaseous medium. In such a way, a novel multipurpose antenna of utmost simplicity is obtained. From the computation of the self and mutual impedances, a control of the antenna radiation pattern by means of the induced currents in the parasitic elements is modelled. To illustrate the procedure, the technique will be applied to the variation of the side lobe level of a pencil beam and to obtain a flat-topped broadside beam from the same pencil beam, something with high interest for satellite applications. The proposed methodology represents an advance on the development of multipurpose antennas which resounds in simplicity not only in the reconfiguration of antenna beams, but in applications for the detection of particulate matter and/or measurements of the atmospheric dielectric constant.

MOMENTUM OF AN ELECTROMAGNETIC WAVE IN TIME-VARYING DIELECTRIC MEDIA

In the context of the Abraham–Minkowski controversy, the problem of the propagation of electromagnetic waves in a linear dielectric medium with a time-varying dielectric constant is considered. It is shown that the momentum of an electromagnetic wave in the form of Minkowski is preserved with an instantaneous change in the dielectric permittivity of the medium. At the same time, the Abraham momentum is not conserved, despite the spatial homogeneity of the problem. This circumstance is interpreted as a manifestation of the Abraham force.

Two-level systems coupled to Graphene plasmons: A Lindblad equation approach

In this paper, we review the theory of open quantum systems and macroscopic quantum electrodynamics, providing a self-contained account of many aspects of these two theories. The former is presented in the context of a qubit coupled to a electromagnetic thermal bath, the latter is presented in the context of a quantization scheme for surface-plasmon polaritons (SPPs) in graphene based on Langevin noise currents. This includes a calculation of the dyadic Green’s function (in the electrostatic limit) for a Graphene sheet between two semi-infinite linear dielectric media, and its subsequent application to the construction of SPP creation and annihilation operators. We then bring the two fields together and discuss the entanglement of two qubits in the vicinity of a graphene sheet which supports SPPs. The two qubits communicate with each other via the emission and absorption of SPPs. We find that a Schrödinger cat state involving the two qubits can be partially protected from decoherence by taking advantage of the dissipative dynamics in graphene. A comparison is also drawn between the dynamics at zero temperature, obtained via Schrödinger’s equation, and at finite temperature, obtained using the Lindblad equation.

Light in dielectric media and scalar fields in a de Sitter spacetime

In the present work we discuss the behavior of light in a linear dielectric medium with a time-varying electric permittivity that increases exponentially at a constant rate and of a scalar field in a de Sitter spacetime, in both the classical and quantum contexts. Notably, we find that the behavior of these two systems are identical and can be described by similar Hamiltonians. By using the Lewis–Riesenfeld invariant method together with Fock states we solve the time-dependent Schrödinger equation for this problem and use its solutions to construct coherent states for the scalar field. Finally, we employ both the Fock and coherent states to evaluate some important properties of the quantized scalar field, such as expectation values of the amplitude and momentum of each mode their variances and the respective uncertainty principle.

Nanofocusing: reaching out

Nanofocusing, the term coined by Mark Stockman, has been observed in many different tapered waveguide configurations, demonstrating the possibility for optical modes to be efficiently delivered to and concentrated into nanoscale regions far beyond the diffraction limit in dielectric media. Strong and broadband local field enhancement and slowdown effects associated with the nanofocusing have been exploited for enhancing linear and nonlinear optical phenomena and reaching out to a broad spectrum of diverse applications, from electron generation to water vaporization. Starting with the historical background, we carefully elaborate on the basic concepts and mechanisms involved. We then provide examples of the latest developments in this exciting quest for bringing the fundamental physical phenomenon of nanofocusing into the realm of practical applications in modern nanotechnology.

Pengukuran dan Analisis High Frequency Current Transformer Pendeteksi Partial Discharge

The lifetime of high voltage equipment is very dependent on the condition of insulation, poor insulation means the life span of high voltage equipment is getting shorter. Partial Discharge is one of the causes of deterioration of high voltage equipment insulation. The ability to know the phenomenon of partial discharge in equipment becomes very important and adds value to the maintenance of high voltage equipment. Many explanations regarding partial discharge, partial discharge is the lack of uniformity of the electric field in the isolation or dielectric media which will result in the phenomenon of Partial Discharge where this will lead to the failure of the isolation media. Partial Discharge that occurs continuously can cause damage (breakdown) on a high voltage equipment. Therefore, before a high voltage device is used, Partial Discharge detection is necessary. Partial Discharge Detection can use the Partial Discharge measurement circuit. In testing partial discharges can be tested using a sensor with various circuits including High Frequency Current Transformers (HFCT) so that this research will discuss one part of the Partial Discharge measurement circuit, the HFCT detector. Hopefully, the HFCT detector can be further developed and can be used for better partial discharge detection.