Huygen's principle in a moving isotropic homogeneous and linear medium
Huygen principle for analysis of electromagnetic field in moving isotropic homogeneous and linear medium
HUYGEN PRINCIPLE↗
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Results for “ELECTROMAGNETIC FIELDS”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Amplitude/phase modulation and spectrum of the vertical-cavity surface-emitting laser output
A new approach has been proposed for analysing the dynamics of the laser field amplitude on the basis of Maxwell’s equations. This approach has been used to develop a theory for calculating modulation characteristics of vertical-cavity surface-emitting lasers in the small modulation limit. The present analysis allows one to sequentially examine the dynamics of the amplitude and phase of the electromagnetic field of light in the framework of a single physical model, proceeding from fundamental principles. The proposed approach offers a natural and unique procedure for finding all laser cavity parameters necessary for calculation. An analytical calculation in the ‘small’-signal approximation has ensured good agreement with experimental data. (paper)
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
What is a photon: structure and wave function
Based on the model of a photon as a ‘radiation oscillator’ of a field moving in space with the speed of light and having a zero rest mass, we have constructed a wave function that describes the photon states of the electromagnetic field. It has been suggested that the entire space where the field is present splits into separate regions of the order of the radiation wavelength, within which the field is coherent and the total field energy is equal to the photon energy. (paper)
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
The electromagnetic torques on spherical earth satellites in a rarefied partially ionized atmosphere
Electromagnetic field effects on rotation rate of satellite in polar orbit - Echo II
POLAR ORBIT↗
Microcomputerized electric field meter diagnostic and calibration system
A computerized field meter calibration system which includes an apparatus for testing the calibration of field meters normally utilized for measuring electromagnetic field potentials is described. A reference voltage is applied to the field meter for causing signals to be produced on the output terminals thereof. A bank of relays is provided for selectively connecting output terminals of the field meter to a multiplexer by means of a digital voltmeter and an oscilloscope. A frequency-shift-keyed receiver is also connected to one of the terminals of the field meter for transmitting and converting a frequency shift keyed signal to a digital signal which is, subsequently, applied to the multiplexer.
Holley, L. D.↗
A kinetic study of solar wind mass loading and cometary bow shocks
The kinetic processes associated with solar wind mass loading due to pickup of cometary ions, and the formation of cometary bow shocks were investigated numerically using a hybrid simulation code described by Leroy et al. (1981), in which solar wind protons and heavy cometary ions are treated kinetically, but the electrons are treated as a massless fluid. It was found that the solar wind decelaration and pickup of cometary ions take place through both the macroscopic electromagnetic fields embedded in the solar wind and the microscopic field associated with low-frequency electromagnetic waves that are generated by the unstable velocity distribution function of the cometary ions. The results of the main simulation runs at various cone angles are described and compared with the recent observations of comets Giacobini-Zinner and Halley.
Omidi, N.↗
Geographical Variations In Measured Lightning Fields
Brief report describes continuing program of measurements to determine variations, caused by local terrain, in vertical electric fields radiated by distant lightning. Lightning electromagnetic field increased or decreased with respect to nominal value, depending on slope of local terrain, extent of local vegitation, and distances, sizes, and shapes of nearby structures.
Maier, Launa↗
Quadratic squeezing: An overview
The amplitude of the electric field of a mode of the electromagnetic field is not a fixed quantity: there are always quantum mechanical fluctuations. The amplitude, having both a magnitude and a phase, is a complex number and is described by the mode annihilation operator a. It is also possible to characterize the amplitude by its real and imaginary parts which correspond to the Hermitian and anti-Hermitian parts of a, X sub 1 = 1/2(a(sup +) + a) and X sub 2 = i/2(a(sup +) - a), respectively. These operators do not commute and, as a result, obey the uncertainty relation (h = 1) delta X sub 1(delta X sub 2) greater than or = 1/4. From this relation we see that the amplitude fluctuates within an 'error box' in the complex plane whose area is at least 1/4. Coherent states, among them the vacuum state, are minimum uncertainty states with delta X sub 1 = delta X sub 2 = 1/2. A squeezed state, squeezed in the X sub 1 direction, has the property that delta X sub 1 is less than 1/2. A squeezed state need not be a minimum uncertainty state, but those that are can be obtained by applying the squeeze operator.
Hillery, M.↗
Theoretical study on optical response in nanostructures in the Born–Markov regime: The role of spontaneous emission and dephasing
We theoretically study the linear and nonlinear optical susceptibility in a nanostructure that interacts with a classical monochromatic optical field, by means of the solution of a Born–Markov master equation in the Lindblad form, considering as environment for the system the quantum vacuum of the continuum of modes of the external electromagnetic field. The processes of spontaneous emission and dephasing between two levels of the nanostructured quantum system are studied formally, within the framework of the quantum theory of open systems. It was found that the phenomenological master equation corresponds to a Born–Markov master equation in the Lindblad form that considers only the dissipative terms of spontaneous emission and dephasing, provided that the transverse coherence time T{sub 2} is smaller than spontaneous emission time T{sub 1}. Finally, comparative results are presented between the proposed methodology and the conventional method for: optical rectification, optical absorption, generation of second harmonic and generation of third harmonic in a cylindrical quantum dot (CQD) of AsGa∕AsGaAl with a hydrogen-like impurity inside it and under the action of a uniform magnetic field.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
The relativistic dynamics of a point charge in the field of a plane electromagnetic wave traveling in the direction of a uniform static magnetic field
The motion of a charged particle in electromagnetic fields of various geometric configurations and arising from a variety of sources is of intrinsic interest in electromagnetic theory. The particular configuration consisting of a plane wave propagating in the presence of a static uniform magnetic field whose direction is parallel to the wave normal is examined. The analysis presented here is treated within the context of classical electromagnetic theory. A numerical solution - at least to the approximate Lorentz-Dirac equation - is obtained.
Mitchell, T. P.↗
A CFD Study Assisted with Experimental Confirmation for Liquid Shape Control of Electromagnetically Levitated Bulk Materials
Two types of optimized electromagnetic levitators were designed to achieve the free surface shape control of metallic melts as the combined results of the Lorentz force, sample gravity, and surface tension. The levitation behavior of bulk melts was investigated using computational fluid dynamics (CFD) modeling coupled with high-frequency electromagnetic field analysis and the arbitrary Lagrangian–Eulerian (ALE) method. The difference in the oscillation behavior between the solid and molten samples was explained by the damping of the electromagnetic induction and liquid viscosity. The motion of the mass center, melt shape, flow pattern, and Lorentz force in the levitated melt were determined within a wide excitation current range. With the increase in the applied current, the melt’s centroid position rose sharply in the area with low current but displayed a slow increase in the area with high current. Meanwhile, the stable shape of the bulk melt showed the typical transition from a long taper through a short taper and then into a rhombus. The internal flow pattern transformed from a simple double-loop structure to a complex configuration with three or four loops. The dependence of the deformation on the Bond number was analyzed in the two types of levitators. In addition, the stable shape and swing process of the bulk Al melt within the two types of electromagnetic levitation (EML) systems were quantitatively studied under protective inert gas conditions. The melt contour could be well described by the 10th Legendre polynomial function with a deviation of less than 0.5 pct.
36 MATERIALS SCIENCE↗
The dyadic green's function for an infinite moving medium
Derivation of dyadic Green function for electromagnetic field in moving medium using Minkowski theory and method of Fourier analysis
ELECTROMAGNETIC FIELD↗
Fields in the image space of symmetrical focusing reflectors.
Electromagnetic fields scattered by symmetric focused parabolic reflector illuminated by linearly polarized wave incident normally on aperture
Minnett, H. C.↗
Broadband radiation transport in an optically dense gas in the presence of an RF field
The theory of transport of fluctuating double-frequency optical radiation in a gas of three-level atoms in the presence of rf radiation forming a closed excitation circuit has been generalized. The theory is based on the quantum kinetic equations for the atomic density matrix, which are solved together with the wave equations for classical electromagnetic fields. After averaging over the radiation fluctuation ensemble, a transition is made to equations for atomic-field correlation functions and transport equations for the spectral density of fields.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Casimir effect in Very Special Relativity at finite temperature
Recently a great deal of interest in field theories formulated in a Lorentz violating framework has been developed. Here the Very Special Relativity (VSR) is considered. The main aspect in the VSR proposal is that laws of physics are invariant under the subgroups of the Poincaré group preserving the basic elements of special relativity. An important point is that the photon acquires a mass. In this context, the energy–momentum tensor for the electromagnetic field is calculated. From this, the Stefan–Boltzmann law and Casimir effect at finite temperature in VSR are obtained. The effects of temperature are introduced using the Thermo Field Dynamics (TFD) formalism. A comparative analysis with the Casimir effect for the standard electromagnetic case is developed.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Effect of interparticle fields and radiation reaction on beam dynamics
The dynamics of relativistic particles in an intense electromagnetic field can be described by the Landau-Lifshitz (LL) equation, where the radiation reaction (RR) is accounted for via a self-force, and interparticle fields are often neglected as an approximation. However, the inclusion of interparticle fields is necessary to ensure energy-momentum conservation, particularly during coherent emission. Here we present (i) an analytical proof showing that the energy-momentum conservation law of the Hamilton-Rohrlich-Dirac action, which is divergence free and describes a generic system of interacting charges, respects causality and provides physically sensible results; (ii) a simple generalization of the LL equation for many particles evaluated as a function of the total field, i.e., the sum of the external and interparticle fields. By performing first-principles numerical simulations of a neutral, relativistic bunch of electrons and positrons (e − /e + ) colliding with a laser pulse, this theory is shown to satisfy energy-momentum conservation when interparticle fields and RR are simultaneously taken into account; and (iii) the combined effect of interparticle fields and RR primarily affects the tail of the particle energy distribution. Additionally, our first-principles simulations show that the effect of interparticle fields on beam energy loss becomes smaller when most of the radiated energy is incoherent.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Measurement of the environmental broadband electromagnetic waves in a mid-size European city
In this paper, the level of exposure to broadband radiofrequency electromagnetic field in a mid-size European city was evaluated in accordance with the International Commission on Non-ionizing Radiation Protection guidelines from 1998. With the aim to analyse all the potential electromagnetic waves present in the city up to 18 GHz, a total of 271 locations distributed along Terrassa (Spain) have been measured. To show the results in an easy-to-interpret way by the citizen, the results have been represented in a set of raster maps. The measurement results obtained showed that the electromagnetic wave measured in all broadband frequency range along the city is much lower than the safety level according to the international regulations for both public and occupational sectors.
54 ENVIRONMENTAL SCIENCES↗
Axion-photon conversion caused by dielectric interfaces: quantum field calculation
Axion-photon conversion at dielectric interfaces, immersed in a near-homogeneous magnetic field, is the basis for the dielectric haloscope method to search for axion dark matter. In analogy to transition radiation, this process is possible because the photon wave function is modified by the dielectric layers ('Garibian wave function') and is no longer an eigenstate of momentum. A conventional first-order perturbative calculation of the transition probability between a quantized axion state and these distorted photon states provides the microwave production rate. It agrees with previous results based on solving the classical Maxwell equations for the combined system of axions and electromagnetic fields. We argue that in general the average photon production rate is given by our result, independently of the detailed quantum state of the axion field. Moreover, our result provides a new perspective on axion-photon conversion in dielectric haloscopes because the rate is based on an overlap integral between unperturbed axion and photon wave functions, in analogy to the usual treatment of microwave-cavity haloscopes.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗