Proton and neutron electromagnetic form factors and uncertainties

DOE PAGES

Ye, Zhihong; Arrington, John; Hill, Richard J.; ...

2017-12-06

We determine the nucleon electromagnetic form factors and their uncertainties from world electron scattering data. The analysis incorporates two-photon exchange corrections, constraints on the low-Q 2 and high-Q 2 behavior, and additional uncertainties to account for tensions between different data sets and uncertainties in radiative corrections.

Hypercube matrix computation task

NASA Technical Reports Server (NTRS)

Calalo, Ruel H.; Imbriale, William A.; Jacobi, Nathan; Liewer, Paulett C.; Lockhart, Thomas G.; Lyzenga, Gregory A.; Lyons, James R.; Manshadi, Farzin; Patterson, Jean E.

1988-01-01

A major objective of the Hypercube Matrix Computation effort at the Jet Propulsion Laboratory (JPL) is to investigate the applicability of a parallel computing architecture to the solution of large-scale electromagnetic scattering problems. Three scattering analysis codes are being implemented and assessed on a JPL/California Institute of Technology (Caltech) Mark 3 Hypercube. The codes, which utilize different underlying algorithms, give a means of evaluating the general applicability of this parallel architecture. The three analysis codes being implemented are a frequency domain method of moments code, a time domain finite difference code, and a frequency domain finite elements code. These analysis capabilities are being integrated into an electromagnetics interactive analysis workstation which can serve as a design tool for the construction of antennas and other radiating or scattering structures. The first two years of work on the Hypercube Matrix Computation effort is summarized. It includes both new developments and results as well as work previously reported in the Hypercube Matrix Computation Task: Final Report for 1986 to 1987 (JPL Publication 87-18).

First-Principles Modeling Of Electromagnetic Scattering By Discrete and Discretely Heterogeneous Random Media

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Dlugach, Janna M.; Yurkin, Maxim A.; Bi, Lei; Cairns, Brian; Liu, Li; Panetta, R. Lee; Travis, Larry D.; Yang, Ping; Zakharova, Nadezhda T.

2016-01-01

A discrete random medium is an object in the form of a finite volume of a vacuum or a homogeneous material medium filled with quasi-randomly and quasi-uniformly distributed discrete macroscopic impurities called small particles. Such objects are ubiquitous in natural and artificial environments. They are often characterized by analyzing theoretically the results of laboratory, in situ, or remote-sensing measurements of the scattering of light and other electromagnetic radiation. Electromagnetic scattering and absorption by particles can also affect the energy budget of a discrete random medium and hence various ambient physical and chemical processes. In either case electromagnetic scattering must be modeled in terms of appropriate optical observables, i.e., quadratic or bilinear forms in the field that quantify the reading of a relevant optical instrument or the electromagnetic energy budget. It is generally believed that time-harmonic Maxwell's equations can accurately describe elastic electromagnetic scattering by macroscopic particulate media that change in time much more slowly than the incident electromagnetic field. However, direct solutions of these equations for discrete random media had been impracticable until quite recently. This has led to a widespread use of various phenomenological approaches in situations when their very applicability can be questioned. Recently, however, a new branch of physical optics has emerged wherein electromagnetic scattering by discrete and discretely heterogeneous random media is modeled directly by using analytical or numerically exact computer solutions of the Maxwell equations. Therefore, the main objective of this Report is to formulate the general theoretical framework of electromagnetic scattering by discrete random media rooted in the Maxwell- Lorentz electromagnetics and discuss its immediate analytical and numerical consequences. Starting from the microscopic Maxwell-Lorentz equations, we trace the development of the first principles formalism enabling accurate calculations of monochromatic and quasi-monochromatic scattering by static and randomly varying multiparticle groups. We illustrate how this general framework can be coupled with state-of-the-art computer solvers of the Maxwell equations and applied to direct modeling of electromagnetic scattering by representative random multi-particle groups with arbitrary packing densities. This first-principles modeling yields general physical insights unavailable with phenomenological approaches. We discuss how the first-order-scattering approximation, the radiative transfer theory, and the theory of weak localization of electromagnetic waves can be derived as immediate corollaries of the Maxwell equations for very specific and well-defined kinds of particulate medium. These recent developments confirm the mesoscopic origin of the radiative transfer, weak localization, and effective-medium regimes and help evaluate the numerical accuracy of widely used approximate modeling methodologies.

First-principles modeling of electromagnetic scattering by discrete and discretely heterogeneous random media.

PubMed

Mishchenko, Michael I; Dlugach, Janna M; Yurkin, Maxim A; Bi, Lei; Cairns, Brian; Liu, Li; Panetta, R Lee; Travis, Larry D; Yang, Ping; Zakharova, Nadezhda T

2016-05-16

A discrete random medium is an object in the form of a finite volume of a vacuum or a homogeneous material medium filled with quasi-randomly and quasi-uniformly distributed discrete macroscopic impurities called small particles. Such objects are ubiquitous in natural and artificial environments. They are often characterized by analyzing theoretically the results of laboratory, in situ , or remote-sensing measurements of the scattering of light and other electromagnetic radiation. Electromagnetic scattering and absorption by particles can also affect the energy budget of a discrete random medium and hence various ambient physical and chemical processes. In either case electromagnetic scattering must be modeled in terms of appropriate optical observables, i.e., quadratic or bilinear forms in the field that quantify the reading of a relevant optical instrument or the electromagnetic energy budget. It is generally believed that time-harmonic Maxwell's equations can accurately describe elastic electromagnetic scattering by macroscopic particulate media that change in time much more slowly than the incident electromagnetic field. However, direct solutions of these equations for discrete random media had been impracticable until quite recently. This has led to a widespread use of various phenomenological approaches in situations when their very applicability can be questioned. Recently, however, a new branch of physical optics has emerged wherein electromagnetic scattering by discrete and discretely heterogeneous random media is modeled directly by using analytical or numerically exact computer solutions of the Maxwell equations. Therefore, the main objective of this Report is to formulate the general theoretical framework of electromagnetic scattering by discrete random media rooted in the Maxwell-Lorentz electromagnetics and discuss its immediate analytical and numerical consequences. Starting from the microscopic Maxwell-Lorentz equations, we trace the development of the first-principles formalism enabling accurate calculations of monochromatic and quasi-monochromatic scattering by static and randomly varying multiparticle groups. We illustrate how this general framework can be coupled with state-of-the-art computer solvers of the Maxwell equations and applied to direct modeling of electromagnetic scattering by representative random multi-particle groups with arbitrary packing densities. This first-principles modeling yields general physical insights unavailable with phenomenological approaches. We discuss how the first-order-scattering approximation, the radiative transfer theory, and the theory of weak localization of electromagnetic waves can be derived as immediate corollaries of the Maxwell equations for very specific and well-defined kinds of particulate medium. These recent developments confirm the mesoscopic origin of the radiative transfer, weak localization, and effective-medium regimes and help evaluate the numerical accuracy of widely used approximate modeling methodologies.

First-principles modeling of electromagnetic scattering by discrete and discretely heterogeneous random media

PubMed Central

Mishchenko, Michael I.; Dlugach, Janna M.; Yurkin, Maxim A.; Bi, Lei; Cairns, Brian; Liu, Li; Panetta, R. Lee; Travis, Larry D.; Yang, Ping; Zakharova, Nadezhda T.

2018-01-01

A discrete random medium is an object in the form of a finite volume of a vacuum or a homogeneous material medium filled with quasi-randomly and quasi-uniformly distributed discrete macroscopic impurities called small particles. Such objects are ubiquitous in natural and artificial environments. They are often characterized by analyzing theoretically the results of laboratory, in situ, or remote-sensing measurements of the scattering of light and other electromagnetic radiation. Electromagnetic scattering and absorption by particles can also affect the energy budget of a discrete random medium and hence various ambient physical and chemical processes. In either case electromagnetic scattering must be modeled in terms of appropriate optical observables, i.e., quadratic or bilinear forms in the field that quantify the reading of a relevant optical instrument or the electromagnetic energy budget. It is generally believed that time-harmonic Maxwell’s equations can accurately describe elastic electromagnetic scattering by macroscopic particulate media that change in time much more slowly than the incident electromagnetic field. However, direct solutions of these equations for discrete random media had been impracticable until quite recently. This has led to a widespread use of various phenomenological approaches in situations when their very applicability can be questioned. Recently, however, a new branch of physical optics has emerged wherein electromagnetic scattering by discrete and discretely heterogeneous random media is modeled directly by using analytical or numerically exact computer solutions of the Maxwell equations. Therefore, the main objective of this Report is to formulate the general theoretical framework of electromagnetic scattering by discrete random media rooted in the Maxwell–Lorentz electromagnetics and discuss its immediate analytical and numerical consequences. Starting from the microscopic Maxwell–Lorentz equations, we trace the development of the first-principles formalism enabling accurate calculations of monochromatic and quasi-monochromatic scattering by static and randomly varying multiparticle groups. We illustrate how this general framework can be coupled with state-of-the-art computer solvers of the Maxwell equations and applied to direct modeling of electromagnetic scattering by representative random multi-particle groups with arbitrary packing densities. This first-principles modeling yields general physical insights unavailable with phenomenological approaches. We discuss how the first-order-scattering approximation, the radiative transfer theory, and the theory of weak localization of electromagnetic waves can be derived as immediate corollaries of the Maxwell equations for very specific and well-defined kinds of particulate medium. These recent developments confirm the mesoscopic origin of the radiative transfer, weak localization, and effective-medium regimes and help evaluate the numerical accuracy of widely used approximate modeling methodologies. PMID:29657355

Electromagnetic scattering and emission by a fixed multi-particle object in local thermal equilibrium: General formalism.

PubMed

Mishchenko, Michael I

2017-10-01

The majority of previous studies of the interaction of individual particles and multi-particle groups with electromagnetic field have focused on either elastic scattering in the presence of an external field or self-emission of electromagnetic radiation. In this paper we apply semi-classical fluctuational electrodynamics to address the ubiquitous scenario wherein a fixed particle or a fixed multi-particle group is exposed to an external quasi-polychromatic electromagnetic field as well as thermally emits its own electromagnetic radiation. We summarize the main relevant axioms of fluctuational electrodynamics, formulate in maximally rigorous mathematical terms the general scattering-emission problem for a fixed object, and derive such fundamental corollaries as the scattering-emission volume integral equation, the Lippmann-Schwinger equation for the dyadic transition operator, the multi-particle scattering-emission equations, and the far-field limit. We show that in the framework of fluctuational electrodynamics, the computation of the self-emitted component of the total field is completely separated from that of the elastically scattered field. The same is true of the computation of the emitted and elastically scattered components of quadratic/bilinear forms in the total electromagnetic field. These results pave the way to the practical computation of relevant optical observables.

Research in Antenna Technology, Radar Technology and Electromagnetic Scattering Phenomena

DTIC Science & Technology

2015-04-06

a group of six researchers in the fields of electromagnetics , radar and antenna technology. Research was conducted during this reporting period in...Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 Research in Antenna technology, Radar Technology and Electromagnetic Scattering Phenomena...Matrix Theory Based on Gaussian Beams………...65 4.5.3 Array realization of complex-source beam……………………………85 4.5.4 Electromagnetic Scattering-Matrix

Electromagnetic Scattering Analysis of Large Size Asteroids/Comets for Reflection/Transmission Tomography (RTT)

NASA Technical Reports Server (NTRS)

Deshpande, Manohar

2011-01-01

A precise knowledge of the interior structure of asteroids, comets, and Near Earth Objects (NEO) is important to assess the consequences of their impacts with the Earth and develop efficient mitigation strategies. Knowledge of their interior structure also provides opportunities for extraction of raw materials for future space activities. Low frequency radio sounding is often proposed for investigating interior structures of asteroids and NEOs. For designing and optimizing radio sounding instrument it is advantageous to have an accurate and efficient numerical simulation model of radio reflection and transmission through large size bodies of asteroid shapes. In this presentation we will present electromagnetic (EM) scattering analysis of electrically large size asteroids using (1) a weak form formulation and (2) also a more accurate hybrid finite element method/method of moments (FEM/MOM) to help estimate their internal structures. Assuming the internal structure with known electrical properties of a sample asteroid, we first develop its forward EM scattering model. From the knowledge of EM scattering as a function of frequency and look angle we will then present the inverse scattering procedure to extract its interior structure image. Validity of the inverse scattering procedure will be presented through few simulation examples.

Electromagnetic wave scattering from rough terrain

NASA Astrophysics Data System (ADS)

Papa, R. J.; Lennon, J. F.; Taylor, R. L.

1980-09-01

This report presents two aspects of a program designed to calculate electromagnetic scattering from rough terrain: (1) the use of statistical estimation techniques to determine topographic parameters and (2) the results of a single-roughness-scale scattering calculation based on those parameters, including comparison with experimental data. In the statistical part of the present calculation, digitized topographic maps are used to generate data bases for the required scattering cells. The application of estimation theory to the data leads to the specification of statistical parameters for each cell. The estimated parameters are then used in a hypothesis test to decide on a probability density function (PDF) that represents the height distribution in the cell. Initially, the formulation uses a single observation of the multivariate data. A subsequent approach involves multiple observations of the heights on a bivariate basis, and further refinements are being considered. The electromagnetic scattering analysis, the second topic, calculates the amount of specular and diffuse multipath power reaching a monopulse receiver from a pulsed beacon positioned over a rough Earth. The program allows for spatial inhomogeneities and multiple specular reflection points. The analysis of shadowing by the rough surface has been extended to the case where the surface heights are distributed exponentially. The calculated loss of boresight pointing accuracy attributable to diffuse multipath is then compared with the experimental results. The extent of the specular region, the use of localized height variations, and the effect of the azimuthal variation in power pattern are all assessed.

Analysis of the electromagnetic scattering from an inlet geometry with lossy walls

NASA Technical Reports Server (NTRS)

Myung, N. H.; Pathak, P. H.; Chunang, C. D.

1985-01-01

One of the primary goals is to develop an approximate but sufficiently accurate analysis for the problem of electromagnetic (EM) plane wave scattering by an open ended, perfectly-conducting, semi-infinite hollow circular waveguide (or duct) with a thin, uniform layer of lossy or absorbing material on its inner wall, and with a simple termination inside. The less difficult but useful problem of the EM scattering by a two-dimensional (2-D), semi-infinite parallel plate waveguide with an impedance boundary condition on the inner walls was chosen initially for analysis. The impedance boundary condition in this problem serves to model a thin layer of lossy dielectric/ferrite coating on the otherwise perfectly-conducting interior waveguide walls. An approximate but efficient and accurate ray solution was obtained recently. That solution is presently being extended to the case of a moderately thick dielectric/ferrite coating on the walls so as to be valid for situations where the impedance boundary condition may not remain sufficiently accurate.

Geometric phase coded metasurface: from polarization dependent directive electromagnetic wave scattering to diffusion-like scattering.

PubMed

Chen, Ke; Feng, Yijun; Yang, Zhongjie; Cui, Li; Zhao, Junming; Zhu, Bo; Jiang, Tian

2016-10-24

Ultrathin metasurface compromising various sub-wavelength meta-particles offers promising advantages in controlling electromagnetic wave by spatially manipulating the wavefront characteristics across the interface. The recently proposed digital coding metasurface could even simplify the design and optimization procedures due to the digitalization of the meta-particle geometry. However, current attempts to implement the digital metasurface still utilize several structural meta-particles to obtain certain electromagnetic responses, and requiring time-consuming optimization especially in multi-bits coding designs. In this regard, we present herein utilizing geometric phase based single structured meta-particle with various orientations to achieve either 1-bit or multi-bits digital metasurface. Particular electromagnetic wave scattering patterns dependent on the incident polarizations can be tailored by the encoded metasurfaces with regular sequences. On the contrast, polarization insensitive diffusion-like scattering can also been successfully achieved by digital metasurface encoded with randomly distributed coding sequences leading to substantial suppression of backward scattering in a broadband microwave frequency. The proposed digital metasurfaces provide simple designs and reveal new opportunities for controlling electromagnetic wave scattering with or without polarization dependence.

Geometric phase coded metasurface: from polarization dependent directive electromagnetic wave scattering to diffusion-like scattering

PubMed Central

Chen, Ke; Feng, Yijun; Yang, Zhongjie; Cui, Li; Zhao, Junming; Zhu, Bo; Jiang, Tian

2016-01-01

Ultrathin metasurface compromising various sub-wavelength meta-particles offers promising advantages in controlling electromagnetic wave by spatially manipulating the wavefront characteristics across the interface. The recently proposed digital coding metasurface could even simplify the design and optimization procedures due to the digitalization of the meta-particle geometry. However, current attempts to implement the digital metasurface still utilize several structural meta-particles to obtain certain electromagnetic responses, and requiring time-consuming optimization especially in multi-bits coding designs. In this regard, we present herein utilizing geometric phase based single structured meta-particle with various orientations to achieve either 1-bit or multi-bits digital metasurface. Particular electromagnetic wave scattering patterns dependent on the incident polarizations can be tailored by the encoded metasurfaces with regular sequences. On the contrast, polarization insensitive diffusion-like scattering can also been successfully achieved by digital metasurface encoded with randomly distributed coding sequences leading to substantial suppression of backward scattering in a broadband microwave frequency. The proposed digital metasurfaces provide simple designs and reveal new opportunities for controlling electromagnetic wave scattering with or without polarization dependence. PMID:27775064

Low frequency acoustic and electromagnetic scattering

NASA Technical Reports Server (NTRS)

Hariharan, S. I.; Maccamy, R. C.

1986-01-01

This paper deals with two classes of problems arising from acoustics and electromagnetics scattering in the low frequency stations. The first class of problem is solving Helmholtz equation with Dirichlet boundary conditions on an arbitrary two dimensional body while the second one is an interior-exterior interface problem with Helmholtz equation in the exterior. Low frequency analysis show that there are two intermediate problems which solve the above problems accurate to 0(k/2/ log k) where k is the frequency. These solutions greatly differ from the zero frequency approximations. For the Dirichlet problem numerical examples are shown to verify the theoretical estimates.

A Discrete Scatterer Technique for Evaluating Electromagnetic Scattering from Trees

DTIC Science & Technology

2016-09-01

ARL-TR-7799 ● SEP 2016 US Army Research Laboratory A Discrete Scatterer Technique for Evaluating Electromagnetic Scattering from...longer needed. Do not return it to the originator. ARL-TR-7799 ● SEP 2016 US Army Research Laboratory A Discrete Scatterer Technique...DD-MM-YYYY) September 2016 2. REPORT TYPE Technical Report 3. DATES COVERED (From - To) 2015–2016 4. TITLE AND SUBTITLE A Discrete Scatterer

Spectral peculiarities of electromagnetic wave scattering by Veselago's cylinders

NASA Astrophysics Data System (ADS)

Sukhov, S. V.; Shevyakhov, N. S.

2006-03-01

The results are presented of spectral calculations of extinction cross-section for scattering of E- and H-polarized electromagnetic waves by cylinders made of Veselago material. The insolvency of previously developed models of scattering is demonstrated. It is shown that correct description of scattering requires separate consideration of both electric and magnetic subsystems.

Spectral peculiarities of electromagnetic wave scattered by Veselago's cylinders

NASA Astrophysics Data System (ADS)

Sukhov, S. V.; Shevyakhov, N. S.

2005-09-01

The results are presented of spectral calculations of extinction cross-section for scattering of E- and H-polarized electromagnetic waves by cylinders made of Veselago material. The insolvency of previously developed models of scattering is demonstrated. It is shown that correct description of scattering requires separate consideration of both electric and magnetic subsystems.

Effects on RCS of a perfect electromagnetic conductor sphere in the presence of anisotropic plasma layer

NASA Astrophysics Data System (ADS)

Ghaffar, A.; Hussan, M. M.; Illahi, A.; Alkanhal, Majeed A. S.; Ur Rehman, Sajjad; Naz, M. Y.

2018-01-01

Effects on RCS of perfect electromagnetic conductor (PEMC) sphere by coating with anisotropic plasma layer are studied in this paper. The incident, scattered and transmitted electromagnetic fields are expanded in term of spherical vector wave functions using extended classical theory of scattering. Co and cross-polarized scattered field coefficients are obtained at the interface of free space-anisotropic plasma and at anisotropic plasma-PEMC sphere core by scattering matrices method. The presented analytical expressions are general for any perfect conducting sphere (PMC, PEC, or PEMC) with general anisotropic/isotropic material coatings that include plasma and metamaterials. The behavior of the forward and backscattered radar cross section of PEMC sphere with the variation of the magnetic field strength, incident frequency, plasma density, and effective collision frequency for the co-polarized and the cross polarized fields are investigated. It is also observed from the obtained results that anisotropic layer on PEMC sphere shows reciprocal behavior as compared to isotopic plasma layer on PEMC sphere. The comparisons of the numerical results of the presented analytical expressions with available results of some special cases show the correctness of the analysis.

Electromagnetic Scattering by Multiple Cavities Embedded in the Infinite 2D Ground Plane

DTIC Science & Technology

2014-07-01

Electromagnetic Scattering by Multiple Cavities Embedded in the Infinite 2D Ground Plane Peijun Li 1 and Aihua W. Wood 2 1 Department of...of the electromagnetic wave scattering by multiple open cavities, which are embedded in an infinite two-dimensional ground plane . By introducing a...equation, variational formulation. I. INTRODUCTION A cavity is referred to as a local perturbation of the infinite ground plane . Given the cavity

Radical-Driven Silicon Surface Passivation for Organic-Inorganic Hybrid Photovoltaics

NASA Astrophysics Data System (ADS)

Chandra, Nitish

The advent of metamaterials has increased the complexity of possible light-matter interactions, creating gaps in knowledge and violating various commonly used approximations and rendering some common mathematical frameworks incomplete. Our forward scattering experiments on metallic shells and cavities have created a need for a rigorous geometry-based analysis of scattering problems and more rigorous current distribution descriptions in the volume of the scattering object. In order to build an accurate understanding of these interactions, we have revisited the fundamentals of Maxwell's equations, electromagnetic potentials and boundary conditions to build a bottom-up geometry-based analysis of scattering. Individual structures or meta-atoms can be designed to localize the incident electromagnetic radiation in order to create a change in local constitutive parameters and possible nonlinear responses. Hence, in next generation engineered materials, an accurate determination of current distribution on the surface and in the structure's volume play an important role in describing and designing desired properties. Multipole expansions of the exact current distribution determined using principles of differential geometry provides an elegant way to study these local interactions of meta-atoms. The dynamics of the interactions can be studied using the behavior of the polarization and magnetization densities generated by localized current densities interacting with the electromagnetic potentials associated with the incident waves. The multipole method combined with propagation of electromagnetic potentials can be used to predict a large variety of linear and nonlinear physical phenomena. This has been demonstrated in experiments that enable the analog detection of sources placed at subwavelength separation by using time reversal of observed signals. Time reversal is accomplished by reversing the direction of the magnetic dipole in bianisotropic metasurfaces while simultaneously providing a method to reduce the losses often observed when light interacts with meta-structures.

Radar cross section studies

NASA Technical Reports Server (NTRS)

Burnside, W. D.; Dominek, A. K.; Gupta, I. J.; Newman, E. H.; Pathak, P. H.; Peters, L., Jr.

1987-01-01

The ultimate goal is to generate experimental techniques and computer codes of rather general capability that would enable the aerospace industry to evaluate the scattering properties of aerodynamic shapes. Another goal involves developing an understanding of scattering mechanisms so that modification of the vehicular structure could be introduced within constraints set by aerodynamics. The development of indoor scattering measurement systems with special attention given to the compact range is another goal. There has been considerable progress in advancing state-of-the-art scattering measurements and control and analysis of the electromagnetic scattering from general targets.

Impressed sources and fields in the volume-integral-equation formulation of electromagnetic scattering by a finite object: A tutorial

NASA Astrophysics Data System (ADS)

Mishchenko, Michael I.; Yurkin, Maxim A.

2018-07-01

Although free space cannot generate electromagnetic waves, the majority of existing accounts of frequency-domain electromagnetic scattering by particles and particle groups are based on the postulate of existence of an impressed incident field, usually in the form of a plane wave. In this tutorial we discuss how to account for the actual existence of impressed source currents rather than impressed incident fields. Specifically, we outline a self-consistent theoretical formalism describing electromagnetic scattering by an arbitrary finite object in the presence of arbitrarily distributed impressed currents, some of which can be far removed from the object and some can reside in its vicinity, including inside the object. To make the resulting formalism applicable to a wide range of scattering-object morphologies, we use the framework of the volume integral equation formulation of electromagnetic scattering, couple it with the notion of the transition operator, and exploit the fundamental symmetry property of this operator. Among novel results, this tutorial includes a streamlined proof of fundamental symmetry (reciprocity) relations, a simplified derivation of the Foldy equations, and an explicit analytical expression for the transition operator of a multi-component scattering object.

Wave propagation, scattering and emission in complex media

NASA Astrophysics Data System (ADS)

Jin, Ya-Qiu

I. Polarimetric scattering and SAR imagery. EM wave propagation and scattering in polarimetric SAR interferometry / S. R. Cloude. Terrain topographic inversion from single-pass polarimetric SAR image data by using polarimetric stokes parameters and morphological algorithm / Y. Q. Jin, L. Luo. Road detection in forested area using polarimetric SAR / G. W. Dong ... [et al.]. Research on some problems about SAR radiometric resolution / G. Dong ... [et al.]. A fast image matching algorithm for remote sensing applications / Z. Q. Hou ... [et al.]. A new algorithm of noised remote sensing image fusion based on steerable filters / X. Kang ... [et al.]. Adaptive noise reduction of InSAR data based on anisotropic diffusion models and their applications to phase unwrapping / C. Wang, X. Gao, H. Zhang -- II. Scattering from randomly rough surfaces. Modeling tools for backscattering from rough surfaces / A. K. Fung, K. S. Chen. Pseudo-nondiffracting beams from rough surface scattering / E. R. Méndez, T. A. Leskova, A. A. Maradudin. Surface roughness clutter effects in GPR modeling and detection / C. Rappaport. Scattering from rough surfaces with small slopes / M. Saillard, G. Soriano. Polarization and spectral characteristics of radar signals reflected by sea-surface / V. A. Butko, V. A. Khlusov, L. I. Sharygina. Simulation of microwave scattering from wind-driven ocean surfaces / M. Y. Xia ... [et al.]. HF surface wave radar tests at the Eastern China Sea / X. B. Wu ... [et al.] -- III. Electromagnetics of complex materials. Wave propagation in plane-parallel metamaterial and constitutive relations / A. Ishimaru ... [et al.]. Two dimensional periodic approach for the study of left-handed metamaterials / T. M. Grzegorczyk ... [et al.]. Numerical analysis of the effective constitutive parameters of a random medium containing small chiral spheres / Y. Nanbu, T. Matsuoka, M. Tateiba. Wave propagation in inhomogeneous media: from the Helmholtz to the Ginzburg -Landau equation / M. Gitterman. Transformation of the spectrum of scattered radiation in randomly inhomogeneous absorptive plasma layer / G. V. Jandieri, G. D. Aburjunia, V. G. Jandieri. Numerical analysis of microwave heating on saponification reaction / K. Huang, K. Jia -- IV. Scattering from complex targets. Analysis of electromagnetic scattering from layered crossed-gratings of circular cylinders using lattice sums technique / K. Yasumoto, H. T. Jia. Scattering by a body in a random medium / M. Tateiba, Z. Q. Meng, H. El-Ocla. A rigorous analysis of electromagnetic scattering from multilayered crossed-arrays of metallic cylinders / H. T. Jia, K. Yasumoto. Vector models of non-stable and spatially-distributed radar objects / A. Surkov ... [et al.]. Simulation of algorithm of orthogonal signals forming and processing used to estimate back scattering matrix of non-stable radar objects / D. Nosov ... [et al.]. New features of scattering from a dielectric film on a reflecting metal substrate / Z. H. Gu, I. M. Fuks, M. Ciftan. A higher order FDTD method for EM wave propagation in collision plasmas / S. B. Liu, J. J. Mo, N. C. Yuan -- V. Radiative transfer and remote sensing. Simulating microwave emission from Antarctica ice sheet with a coherent model / M. Tedesco, P. Pampaloni. Scattering and emission from inhomogeneous vegetation canopy and alien target by using three-dimensional Vector Radiative Transfer (3D-VRT) equation / Y. Q. Jin, Z. C. Liang. Analysis of land types using high-resolution satellite images and fractal approach / H. G. Zhang ... [et al.]. Data fusion of RADARSAT SAR and DMSP SSM/I for monitoring sea ice of China's Bohai Sea / Y. Q. Jin. Retrieving atmospheric temperature profiles from simulated microwave radiometer data with artificial neural networks / Z. G. Yao, H. B. Chen -- VI. Wave propagation and wireless communication. Wireless propagation in urban environments: modeling and experimental verification / D. Erricolo ... [et al.]. An overview of physics-based wave propagation in forested environment / K. Sarabandi, I. Koh. Angle-of-arrival fluctuations due to meteorological conditions in the diffraction zone of C-band radio waves, propagated over the ground surface / T. A. Tyufilina, A. A. Meschelyakov, M. V. Krutikov. Simulating radio channel statistics using ray based prediction codes / H. L. Bertoni. Measurement and simulation of ultra wideband antenna elements / W. Sörgel, W. Wiesbeck. The experimental investigation of a ground-placed radio complex synchronization system / V. P. Denisov ... [et al.] -- VII. Computational electromagnetics. Analysis of 3-D electromagnetic wave scattering with the Krylov subspace FFT iterative methods / R. S. Chen ... [et al.]. Sparse approximate inverse preconditioned iterative algorithm with block toeplitz matrix for fast analysis of microstrip circuits / L. Mo, R. S. Chen, E. K. N. Yung. An Efficient modified interpolation technique for the translation operators in MLFMA / J. Hu, Z. P. Nie, G. X. Zou. Efficient solution of 3-D vector electromagnetic scattering by CG-MLFMA with partly approximate iteration / J. Hu, Z. P. Nie. The effective constitution at interface of different media / L. G. Zheng, W. X. Zhang. Novel basis functions for quadratic hexahedral edge element / P. Liu ... [et al.]. A higher order FDTD method for EM wave propagation in collision plasmas / S. B. Liu, J. J. Mo, N. C. Yuan. Attenuation of electric field eradiated by underground source / J. P. Dong, Y. G. Gao.

Scattering engineering in continuously shaped metasurface: An approach for electromagnetic illusion

PubMed Central

Guo, Yinghui; Yan, Lianshan; Pan, Wei; Shao, Liyang

2016-01-01

The control of electromagnetic waves scattering is critical in wireless communications and stealth technology. Discrete metasurfaces not only increase the design and fabrication complex but also cause difficulties in obtaining simultaneous electric and optical functionality. On the other hand, discontinuous phase profiles fostered by discrete systems inevitably introduce phase noises to the scattering fields. Here we propose the principle of a scattering-harness mechanism by utilizing continuous gradient phase stemming from the spin-orbit interaction via sinusoidal metallic strips. Furthermore, by adjusting the amplitude and period of the sinusoidal metallic strip, the scattering characteristics of the underneath object can be greatly changed and thus result in electromagnetic illusion. The proposal is validated by full-wave simulations and experiment characterization in microwave band. Our approach featured by continuous phase profile, polarization independent performance and facile implementation may find widespread applications in electromagnetic wave manipulation. PMID:27439474

Scattering engineering in continuously shaped metasurface: An approach for electromagnetic illusion

NASA Astrophysics Data System (ADS)

Guo, Yinghui; Yan, Lianshan; Pan, Wei; Shao, Liyang

2016-07-01

The control of electromagnetic waves scattering is critical in wireless communications and stealth technology. Discrete metasurfaces not only increase the design and fabrication complex but also cause difficulties in obtaining simultaneous electric and optical functionality. On the other hand, discontinuous phase profiles fostered by discrete systems inevitably introduce phase noises to the scattering fields. Here we propose the principle of a scattering-harness mechanism by utilizing continuous gradient phase stemming from the spin-orbit interaction via sinusoidal metallic strips. Furthermore, by adjusting the amplitude and period of the sinusoidal metallic strip, the scattering characteristics of the underneath object can be greatly changed and thus result in electromagnetic illusion. The proposal is validated by full-wave simulations and experiment characterization in microwave band. Our approach featured by continuous phase profile, polarization independent performance and facile implementation may find widespread applications in electromagnetic wave manipulation.

Nonlinear interferometric vibrational imaging

NASA Technical Reports Server (NTRS)

Boppart, Stephen A. (Inventor); Marks, Daniel L. (Inventor)

2009-01-01

A method of examining a sample, which includes: exposing a reference to a first set of electromagnetic radiation, to form a second set of electromagnetic radiation scattered from the reference; exposing a sample to a third set of electromagnetic radiation to form a fourth set of electromagnetic radiation scattered from the sample; and interfering the second set of electromagnetic radiation and the fourth set of electromagnetic radiation. The first set and the third set of electromagnetic radiation are generated from a source; at least a portion of the second set of electromagnetic radiation is of a frequency different from that of the first set of electromagnetic radiation; and at least a portion of the fourth set of electromagnetic radiation is of a frequency different from that of the third set of electromagnetic radiation.

Electromagnetic scattering laws in Weyl systems.

PubMed

Zhou, Ming; Ying, Lei; Lu, Ling; Shi, Lei; Zi, Jian; Yu, Zongfu

2017-11-09

Wavelength determines the length scale of the cross section when electromagnetic waves are scattered by an electrically small object. The cross section diverges for resonant scattering, and diminishes for non-resonant scattering, when wavelength approaches infinity. This scattering law explains the colour of the sky as well as the strength of a mobile phone signal. We show that such wavelength scaling comes from the conical dispersion of free space at zero frequency. Emerging Weyl systems, offering similar dispersion at non-zero frequencies, lead to new laws of electromagnetic scattering that allow cross sections to be decoupled from the wavelength limit. Diverging and diminishing cross sections can be realized at any target wavelength in a Weyl system, providing the ability to tailor the strength of wave-matter interactions for radiofrequency and optical applications.

On the electromagnetic scattering from infinite rectangular conducting grids

NASA Technical Reports Server (NTRS)

Christodoulou, C.

1985-01-01

The study and development of two numerical techniques for the analysis of electromagnetic scattering from a rectangular wire mesh are described. Both techniques follow from one basic formulation and they are both solved in the spectral domain. These techniques were developed as a result of an investigation towards more efficient numerical computation for mesh scattering. These techniques are efficient for the following reasons: (a1) make use of the Fast Fourier Transform; (b2) they avoid any convolution problems by converting integrodifferential equations into algebraic equations; and (c3) they do not require inversions of any matrices. The first method, the SIT or Spectral Iteration Technique, is applied for regions where the spacing between wires is not less than two wavelengths. The second method, the SDCG or Spectral Domain Conjugate Gradient approach, can be used for any spacing between adjacent wires. A study of electromagnetic wave properties, such as reflection coefficient, induced currents and aperture fields, as functions of frequency, angle of incidence, polarization and thickness of wires is presented. Examples and comparisons or results with other methods are also included to support the validity of the new algorithms.

UTD analysis of electromagnetic scattering by flat structures. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Sikta, F. A.; Peters, L., Jr.

1981-01-01

The different scattering mechanisms that contribute to the radar cross of finite flat plates were identified and analyzed. The geometrical theory of diffraction, the equivalent current and the corner diffraction are used for this study. A study of the cross polarized field for a monopole mounted on a plate is presented, using novel edge wave mechanism in the analysis. The results are compared with moment method solutions as well as measured data.

Intrasystem Analysis Program (IAP) code summaries

NASA Astrophysics Data System (ADS)

Dobmeier, J. J.; Drozd, A. L. S.; Surace, J. A.

1983-05-01

This report contains detailed descriptions and capabilities of the codes that comprise the Intrasystem Analysis Program. The four codes are: Intrasystem Electromagnetic Compatibility Analysis Program (IEMCAP), General Electromagnetic Model for the Analysis of Complex Systems (GEMACS), Nonlinear Circuit Analysis Program (NCAP), and Wire Coupling Prediction Models (WIRE). IEMCAP is used for computer-aided evaluation of electromagnetic compatibility (ECM) at all stages of an Air Force system's life cycle, applicable to aircraft, space/missile, and ground-based systems. GEMACS utilizes a Method of Moments (MOM) formalism with the Electric Field Integral Equation (EFIE) for the solution of electromagnetic radiation and scattering problems. The code employs both full matrix decomposition and Banded Matrix Iteration solution techniques and is expressly designed for large problems. NCAP is a circuit analysis code which uses the Volterra approach to solve for the transfer functions and node voltage of weakly nonlinear circuits. The Wire Programs deal with the Application of Multiconductor Transmission Line Theory to the Prediction of Cable Coupling for specific classes of problems.

Electromagnetic Modeling, Optimization and Uncertainty Quantification for Antenna and Radar Systems Surfaces Scattering and Energy Absorption

DTIC Science & Technology

2017-03-06

design of antenna and radar systems, energy absorption and scattering by rough-surfaces. This work has lead to significant new methodologies , including...problems in the field of electromagnetic propagation and scattering, with applicability to design of antenna and radar systems, energy absorption...and scattering by rough-surfaces. This work has lead to significant new methodologies , including introduction of a certain Windowed Green Function

Analysis of electromagnetic scattering by uniaxial anisotropic bispheres.

PubMed

Li, Zheng-Jun; Wu, Zhen-Sen; Li, Hai-Ying

2011-02-01

Based on the generalized multiparticle Mie theory and the Fourier transformation approach, electromagnetic (EM) scattering of two interacting homogeneous uniaxial anisotropic spheres with parallel primary optical axes is investigated. By introducing the Fourier transformation, the EM fields in the uniaxial anisotropic spheres are expanded in terms of the spherical vector wave functions. The interactive scattering coefficients and the expansion coefficients of the internal fields are derived through the continuous boundary conditions on which the interaction of the bispheres is considered. Some selected calculations on the effects of the size parameter, the uniaxial anisotropic absorbing dielectric, and the sphere separation distance are described. The backward radar cross section of two uniaxial anisotropic spheres with a complex permittivity tensor changing with the sphere separation distance is numerically studied. The authors are hopeful that the work in this paper will help provide an effective calibration for further research on the scattering characteristic of an aggregate of anisotropic spheres or other shaped anisotropic particles.

Scattering of Non-Relativistic Charged Particles by Electromagnetic Radiation

NASA Astrophysics Data System (ADS)

Apostol, M.

2017-11-01

The cross-section is computed for non-relativistic charged particles (like electrons and ions) scattered by electromagnetic radiation confined to a finite region (like the focal region of optical laser beams). The cross-section exhibits maxima at scattering angles given by the energy and momentum conservation in multi-photon absorption or emission processes. For convenience, a potential scattering is included and a comparison is made with the well-known Kroll-Watson scattering formula. The scattering process addressed in this paper is distinct from the process dealt with in previous studies, where the scattering is immersed in the radiation field.

User's manual for three dimensional FDTD version A code for scattering from frequency-independent dielectric materials

NASA Technical Reports Server (NTRS)

Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.

1991-01-01

The Finite Difference Time Domain Electromagnetic Scattering Code Version A is a three dimensional numerical electromagnetic scattering code based upon the Finite Difference Time Domain Technique (FDTD). This manual provides a description of the code and corresponding results for the default scattering problem. In addition to the description, the operation, resource requirements, version A code capabilities, a description of each subroutine, a brief discussion of the radar cross section computations, and a discussion of the scattering results.

The Propagation and Scattering of EM Waves in Electrically Large Ducts

NASA Astrophysics Data System (ADS)

Khan, Saeed Mahmood

The electromagnetic scattering from large arbitrarily shaped ducts with complex termination is studied here by a hybrid technique. The propagation of electromagnetic waves in the duct is analyzed in terms of an approximate modal solution. A finite difference technique is employed for computing the reflection characteristics of the complex terminations. Both solutions are combined using the unimoment method. The analysis here is carried out for monostatic RCS and considers only fields backscattered from inside the cavity. Rim-diffraction has been left out. The procedure offers such advantages as in that it is not necessary to find complicated Green's functions, which may not be readily available, when compared with the integral equation method. Hybridization performed by combining an approximate modal technique with a finite difference one makes the scheme numerically efficient. From a computational EM point of view, it brings together a whole spectrum of techniques associated with high frequency modal analysis, Fourier Methods, Radar Cross Section and Scattering, finite difference solution and the Unimoment Method. The practical application of this technique may range from the study of RCS scattered from jet inlets of radar evasive aircraft to submarine communication waveguides.

Transition operators in electromagnetic-wave diffraction theory - General theory

NASA Technical Reports Server (NTRS)

Hahne, G. E.

1992-01-01

A formal theory is developed for the scattering of time-harmonic electromagnetic waves from impenetrable immobile obstacles with given linear, homogeneous, and generally nonlocal boundary conditions of Leontovich (impedance) type for the wave of the obstacle's surface. The theory is modeled on the complete Green's function and the transition (T) operator in time-independent formal scattering theory of nonrelativistic quantum mechanics. An expression for the differential scattering cross section for plane electromagnetic waves is derived in terms of certain matrix elements of the T operator for the obstacle.

Scattering of ultrashort electromagnetic pulses on metal clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Astapenko, V. A., E-mail: astval@mail.ru; Sakhno, S. V.

We have calculated and analyzed the probability of ultrashort electromagnetic pulse (USP) scattering on small metal clusters in the frequency range of plasmon resonances during the field action. The main attention is devoted to dependence of the probability of scattering on the pulse duration for various detunings of the USP carrier frequency from the plasmon resonance frequency. Peculiarities of the USP scattering from plasmon resonances with various figures of merit are revealed.

Scattering of ultrashort electromagnetic pulses on metal clusters

NASA Astrophysics Data System (ADS)

Astapenko, V. A.; Sakhno, S. V.

2016-12-01

We have calculated and analyzed the probability of ultrashort electromagnetic pulse (USP) scattering on small metal clusters in the frequency range of plasmon resonances during the field action. The main attention is devoted to dependence of the probability of scattering on the pulse duration for various detunings of the USP carrier frequency from the plasmon resonance frequency. Peculiarities of the USP scattering from plasmon resonances with various figures of merit are revealed.

Radar Cross Section Studies/Compact Range Research

NASA Technical Reports Server (NTRS)

Burnside, W. D.; Dominek, A. K.; Gupta, I. J.; Newman, E. H.; Pathak, P. H.; Peters, L., Jr.

1988-01-01

A summary is given of the achievements of NASA Grant NsG-1613 by Ohio State University from May 1, 1987 to April 30, 1988. The major topics covered are as follows: (1) electromagnetic scattering analysis; (2) indoor scattering measurement systems; (3) RCS control; (4) waveform processing techniques; (5) material scattering and design studies; (6) design and evaluation of design studies; and (7) antenna studies. Major progress has been made in each of these areas as verified by the numerous publications produced.

Topics in electromagnetic, acoustic, and potential scattering theory

NASA Astrophysics Data System (ADS)

Nuntaplook, Umaporn

With recent renewed interest in the classical topics of both acoustic and electromagnetic aspects for nano-technology, transformation optics, fiber optics, metamaterials with negative refractive indices, cloaking and invisibility, the topic of time-independent scattering theory in quantum mechanics is becoming a useful field to re-examine in the above contexts. One of the key areas of electromagnetic theory scattering of plane electromagnetic waves --- is based on the properties of the refractive indices in the various media. It transpires that the refractive index of a medium and the potential in quantum scattering theory are intimately related. In many cases, understanding such scattering in radially symmetric media is sufficient to gain insight into scattering in more complex media. Meeting the challenge of variable refractive indices and possibly complicated boundary conditions therefore requires accurate and efficient numerical methods, and where possible, analytic solutions to the radial equations from the governing scalar and vector wave equations (in acoustics and electromagnetic theory, respectively). Until relatively recently, researchers assumed a constant refractive index throughout the medium of interest. However, the most interesting and increasingly useful cases are those with non-constant refractive index profiles. In the majority of this dissertation the focus is on media with piecewise constant refractive indices in radially symmetric media. The method discussed is based on the solution of Maxwell's equations for scattering of plane electromagnetic waves from a dielectric (or "transparent") sphere in terms of the related Helmholtz equation. The main body of the dissertation (Chapters 2 and 3) is concerned with scattering from (i) a uniform spherical inhomogeneity embedded in an external medium with different properties, and (ii) a piecewise-uniform central inhomogeneity in the external medium. The latter results contain a natural generalization of the former (previously known) results. The link with time-independent quantum mechanical scattering, via morphology-dependent resonances (MDRs), is discussed in Chapter 2. This requires a generalization of the classical problem for scattering of a plane wave from a uniform spherically-symmetric inhomogeneity (in which the velocity of propagation is a function only of the radial coordinate r. i.e.. c = c(r)) to a piecewise-uniform inhomogeneity. In Chapter 3 the Jost-function formulation of potential scattering theory is used to solve the radial differential equation for scattering which can be converted into an integral equation corresponding via the Jost boundary conditions. The first two iterations for the zero angular momentum case l = 0 are provided for both two-layer and three-layer models. It is found that the iterative technique is most useful for long wavelengths and sufficiently small ratios of interior and exterior wavenumbers. Exact solutions are also provided for these cases. In Chapter 4 the time-independent quantum mechanical 'connection' is exploited further by generalizing previous work on a spherical well potential to the case where a delta 'function' potential is appended to the exterior of the well (for l ≠ 0). This corresponds to an idealization of the former approach to the case of a 'coated sphere'. The poles of the associated 'S-matrix' are important in this regard, since they correspond directly with the morphology-dependent resonances discussed in Chapter 2. These poles (for the l = 0 case, to compare with Nussenzveig's analysis) are tracked in the complex wavenumber plane as the strength of the delta function potential changes. Finally, a set of 4 Appendices is provided to clarify some of the connections between (i) the scattering of acoustic/electromagnetic waves from a penetrable/dielectric sphere and (ii) time-independent potential scattering theory in quantum mechanics. This, it is hoped, will be the subject of future work.

Electromagnetic scattering by impedance structures

NASA Technical Reports Server (NTRS)

Balanis, Constantine A.; Griesser, Timothy

1987-01-01

The scattering of electromagnetic waves from impedance structures is investigated, and current work on antenna pattern calculation is presented. A general algorithm for determining radiation patterns from antennas mounted near or on polygonal plates is presented. These plates are assumed to be of a material which satisfies the Leontovich (or surface impedance) boundary condition. Calculated patterns including reflection and diffraction terms are presented for numerious geometries, and refinements are included for antennas mounted directly on impedance surfaces. For the case of a monopole mounted on a surface impedance ground plane, computed patterns are compared with experimental measurements. This work in antenna pattern prediction forms the basis of understanding of the complex scattering mechanisms from impedance surfaces. It provides the foundation for the analysis of backscattering patterns which, in general, are more problematic than calculation of antenna patterns. Further proposed study of related topics, including surface waves, corner diffractions, and multiple diffractions, is outlined.

Electrostatic lower hybrid waves excited by electromagnetic whistler mode waves scattering from planar magnetic-field-aligned plasma density irregularities

NASA Technical Reports Server (NTRS)

Bell, T. F.; Ngo, H. D.

1990-01-01

This paper presents a theoretical model for electrostatic lower hybrid waves excited by electromagnetic whistler mode waves propagating in regions of the magnetosphere and the topside ionosphere, where small-scale magnetic-field-aligned plasma density irregularities are thought to exist. In this model, the electrostatic waves are excited by linear mode coupling as the incident electromagnetic whistler mode waves scatter from the magnetic-field-aligned plasma density irregularities. Results indicate that high-amplitude short-wavelength (5 to 100 m) quasi-electrostatic whistler mode waves can be excited when electromagnetic whistler mode waves scatter from small-scale planar magnetic-field-aligned plasma density irregularities in the topside ionosphere and magnetosphere.

Compactness and robustness: Applications in the solution of integral equations for chemical kinetics and electromagnetic scattering

NASA Astrophysics Data System (ADS)

Zhou, Yajun

This thesis employs the topological concept of compactness to deduce robust solutions to two integral equations arising from chemistry and physics: the inverse Laplace problem in chemical kinetics and the vector wave scattering problem in dielectric optics. The inverse Laplace problem occurs in the quantitative understanding of biological processes that exhibit complex kinetic behavior: different subpopulations of transition events from the "reactant" state to the "product" state follow distinct reaction rate constants, which results in a weighted superposition of exponential decay modes. Reconstruction of the rate constant distribution from kinetic data is often critical for mechanistic understandings of chemical reactions related to biological macromolecules. We devise a "phase function approach" to recover the probability distribution of rate constants from decay data in the time domain. The robustness (numerical stability) of this reconstruction algorithm builds upon the continuity of the transformations connecting the relevant function spaces that are compact metric spaces. The robust "phase function approach" not only is useful for the analysis of heterogeneous subpopulations of exponential decays within a single transition step, but also is generalizable to the kinetic analysis of complex chemical reactions that involve multiple intermediate steps. A quantitative characterization of the light scattering is central to many meteoro-logical, optical, and medical applications. We give a rigorous treatment to electromagnetic scattering on arbitrarily shaped dielectric media via the Born equation: an integral equation with a strongly singular convolution kernel that corresponds to a non-compact Green operator. By constructing a quadratic polynomial of the Green operator that cancels out the kernel singularity and satisfies the compactness criterion, we reveal the universality of a real resonance mode in dielectric optics. Meanwhile, exploiting the properties of compact operators, we outline the geometric and physical conditions that guarantee a robust solution to the light scattering problem, and devise an asymptotic solution to the Born equation of electromagnetic scattering for arbitrarily shaped dielectric in a non-perturbative manner.

User's manual for three dimensional FDTD version D code for scattering from frequency-dependent dielectric and magnetic materials

NASA Technical Reports Server (NTRS)

Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.

1992-01-01

The Penn State Finite Difference Time Domain Electromagnetic Scattering Code version D is a 3-D numerical electromagnetic scattering code based upon the finite difference time domain technique (FDTD). The manual provides a description of the code and corresponding results for several scattering problems. The manual is organized into 14 sections: introduction; description of the FDTD method; operation; resource requirements; version D code capabilities; a brief description of the default scattering geometry; a brief description of each subroutine; a description of the include file; a section briefly discussing Radar Cross Section computations; a section discussing some scattering results; a sample problem setup section; a new problem checklist; references and figure titles. The FDTD technique models transient electromagnetic scattering and interactions with objects of arbitrary shape and/or material composition. In the FDTD method, Maxwell's curl equations are discretized in time-space and all derivatives (temporal and spatial) are approximated by central differences.

Experimental demonstration of invisible electromagnetic impedance matching cylindrical transformation optics cloak shell

NASA Astrophysics Data System (ADS)

Chen, Mingji; Wang, Changxian; Cheng, Xiaodong; Gong, Congcheng; Song, Weili; Yuan, Xujin; Fang, Daining

2018-04-01

The realization of an ideal invisible cloak implementing transformation optics is still missing. An impedance matching concept is implanted into transformation optics cloak to generate an impedance matching cloak (IMC) shell. In this work, it is proved that impedance matching structure reduces the cloaking structure’s disturbance to a propagating electromagnetic field and improves its invisibility measured by scattering field intensity. Such a cylindrical IMC shell is designed, fabricated with proposed rounded rectangular split-ring-resonators (RR-SRRs), and experimental measurements show the total scattering field of a perfect electric conductor (PEC) cylinder surrounded by an IMC shell is improved greatly compared to the PEC cylinder showing electromagnetic wave front ripple suppression and a considerable scattering shrinking effect. IMC shell backward scattering field is suppressed down to 7.29%, compared to the previous value of 86.7% due to its impedance matching character, and overall scattering field intensity shrinking is down to 19.3% compared to the previously realized value of 56.4%. Sideward scattering field recorded in the experiment also has a remarkable improvement compared to the PEC cylinder. The impedance matching concept might enlighten the realization of an ideal cloak and other novel electromagnetic cloaking and shielding structures.

Modal Ring Method for the Scattering of Electromagnetic Waves

NASA Technical Reports Server (NTRS)

Baumeister, Kenneth J.; Kreider, Kevin L.

1993-01-01

The modal ring method for electromagnetic scattering from perfectly electric conducting (PEC) symmetrical bodies is presented. The scattering body is represented by a line of finite elements (triangular) on its outer surface. The infinite computational region surrounding the body is represented analytically by an eigenfunction expansion. The modal ring method effectively reduces the two dimensional scattering problem to a one-dimensional problem similar to the method of moments. The modal element method is capable of handling very high frequency scattering because it has a highly banded solution matrix.

Modeling of scattering from ice surfaces

NASA Astrophysics Data System (ADS)

Dahlberg, Michael Ross

Theoretical research is proposed to study electromagnetic wave scattering from ice surfaces. A mathematical formulation that is more representative of the electromagnetic scattering from ice, with volume mechanisms included, and capable of handling multiple scattering effects is developed. This research is essential to advancing the field of environmental science and engineering by enabling more accurate inversion of remote sensing data. The results of this research contributed towards a more accurate representation of the scattering from ice surfaces, that is computationally more efficient and that can be applied to many remote-sensing applications.

Spectrum of an electromagnetic light wave on scattering from an anisotropic semisoft boundary medium.

PubMed

Wang, Tao; Jiang, Zhenfei; Ji, Xiaoling; Zhao, Daomu

2016-04-01

Spectral shifts and spectral switches of a polychromatic electromagnetic light wave on scattering from an anisotropic semisoft boundary medium are discussed. It is shown that both the property of the incident field and the character of the scattering medium play roles in the change of the spectrum of the far-zone scattered field. It is also shown that the distribution of the far-zone scattered spectrum, including the magnitude of the spectral shift and the direction at which the spectral switch occurs, is rotationally nonsymmetric.

Long-range monostatic remote sensing of geomaterial structure weak vibrations

NASA Astrophysics Data System (ADS)

Heifetz, Alexander; Bakhtiari, Sasan; Gopalsami, Nachappa; Elmer, Thomas W.; Mukherjee, Souvik

2018-04-01

We study analytically and numerically signal sensitivity in remote sensing measurements of weak mechanical vibration of structures made of typical construction geomaterials, such as concrete. The analysis includes considerations of electromagnetic beam atmospheric absorption, reflection, scattering, diffraction and losses. Comparison is made between electromagnetic frequencies of 35GHz (Ka-band), 94GHz (W-band) and 260GHz (WR-3 waveguide band), corresponding to atmospheric transparency windows of the electromagnetic spectrum. Numerical simulations indicate that 94GHz frequency is optimal in terms of signal sensitivity and specificity for long-distance (>1.5km) sensing of weak multi-mode vibrations.

Plasmon Mapping in Metallic Nanostructures and its Application to Single Molecule Surface Enhanced Raman Scattering: Imaging Electromagnetic Hot-Spots and Analyte Location

DOE Office of Scientific and Technical Information (OSTI.GOV)

Camden, Jon P.

2013-07-12

A major component of this proposal is to elucidate the connection between optical and electron excitation of plasmon modes in metallic nanostructures. These accomplishments are reported: developed a routine protocol for obtaining spatially resolved, low energy EELS spectra, and resonance Rayleigh scattering spectra from the same nanostructures; correlated optical scattering spectra and plasmon maps obtained using STEM/EELS; and imaged electromagnetic hot spots responsible for single-molecule surface-enhanced Raman scattering (SMSERS).

Some examples of exact and approximate solutions in small particle scattering - A progress report

NASA Technical Reports Server (NTRS)

Greenberg, J. M.

1974-01-01

The formulation of basic equations from which the scattering of radiation by a localized variation in a medium is discussed. These equations are developed in both the differential and the integral form. Primary interest is in the scattering of electromagnetic waves for which the solution of the vector wave equation with appropriate boundary conditions must be considered. Scalar scattering by an infinite homogeneous isotropic circular cylinder, and scattering of electromagnetic waves by infinite circular cylinders are treated, and the case of the finite circular cylinder is considered. A procedure is given for obtaining angular scattering distributions from spheroids.

Switchable Scattering Meta-Surfaces for Broadband Terahertz Modulation

PubMed Central

Unlu, M.; Hashemi, M. R.; Berry, C. W.; Li, S.; Yang, S.-H.; Jarrahi, M.

2014-01-01

Active tuning and switching of electromagnetic properties of materials is of great importance for controlling their interaction with electromagnetic waves. In spite of their great promise, previously demonstrated reconfigurable metamaterials are limited in their operation bandwidth due to their resonant nature. Here, we demonstrate a new class of meta-surfaces that exhibit electrically-induced switching in their scattering parameters at room temperature and over a broad range of frequencies. Structural configuration of the subwavelength meta-molecules determines their electromagnetic response to an incident electromagnetic radiation. By reconfiguration of the meta-molecule structure, the strength of the induced electric field and magnetic field in the opposite direction to the incident fields are varied and the scattering parameters of the meta-surface are altered, consequently. We demonstrate a custom-designed meta-surface with switchable scattering parameters at a broad range of terahertz frequencies, enabling terahertz intensity modulation with record high modulation depths and modulation bandwidths through a fully integrated, voltage-controlled device platform at room temperature. PMID:25028123

Quantization of an electromagnetic field in two-dimensional photonic structures based on the scattering matrix formalism ( S-quantization)

NASA Astrophysics Data System (ADS)

Ivanov, K. A.; Nikolaev, V. V.; Gubaydullin, A. R.; Kaliteevski, M. A.

2017-10-01

Based on the scattering matrix formalism, we have developed a method of quantization of an electromagnetic field in two-dimensional photonic nanostructures ( S-quantization in the two-dimensional case). In this method, the fields at the boundaries of the quantization box are expanded into a Fourier series and are related with each other by the scattering matrix of the system, which is the product of matrices describing the propagation of plane waves in empty regions of the quantization box and the scattering matrix of the photonic structure (or an arbitrary inhomogeneity). The quantization condition (similarly to the onedimensional case) is formulated as follows: the eigenvalues of the scattering matrix are equal to unity, which corresponds to the fact that the set of waves that are incident on the structure (components of the expansion into the Fourier series) is equal to the set of waves that travel away from the structure (outgoing waves). The coefficients of the matrix of scattering through the inhomogeneous structure have been calculated using the following procedure: the structure is divided into parallel layers such that the permittivity in each layer varies only along the axis that is perpendicular to the layers. Using the Fourier transform, the Maxwell equations have been written in the form of a matrix that relates the Fourier components of the electric field at the boundaries of neighboring layers. The product of these matrices is the transfer matrix in the basis of the Fourier components of the electric field. Represented in a block form, it is composed by matrices that contain the reflection and transmission coefficients for the Fourier components of the field, which, in turn, constitute the scattering matrix. The developed method considerably simplifies the calculation scheme for the analysis of the behavior of the electromagnetic field in structures with a two-dimensional inhomogeneity. In addition, this method makes it possible to obviate difficulties that arise in the analysis of the Purcell effect because of the divergence of the integral describing the effective volume of the mode in open systems.

Total electron count variability and stratospheric ozone effects on solar backscatter and LWIR emissions

DTIC Science & Technology

2017-03-10

electromagnetic radiation that propagates through a planetary atmosphere. These codes vary in the extent of their scope, incorporated models, and derived...emissive properties of the atmosphere. The propagation of electromagnetic radiation is affected by the scattering and absorption by both air molecules...Mie theory is the collection of the Mie solutions and methods to Maxwell’s Equations, which 35 describe how electromagnetic waves are scattered by

Interaction of electromagnetic and acoustic waves in a stochastic atmosphere

NASA Technical Reports Server (NTRS)

Bhatnagar, N.; Peterson, A. M.

1979-01-01

In the Stanford radio acoustic sounding system (RASS) an electromagnetic signal is made to scatter from a moving acoustic pulse train. Under a Bragg-scatter condition maximum electromagnetic scattering occurs. The scattered radio signal contains temperature and wind information as a function of the acoustic-pulse position. In this investigation RASS performance is assessed in an atmosphere characterized by the presence of turbulence and mean atmospheric parameters. The only assumption made is that the electromagnetic wave is not affected by stochastic perturbations in the atmosphere. It is concluded that the received radio signal depends strongly on the intensity of turbulence for altitudes of the acoustic pulse greater than the coherence length of propagation. The effect of mean vertical wind and mean temperature on the strength of the received signal is also demonstrated to be insignificant. Mean horizontal winds, however, shift the focus of the reflected electromagnetic energy from its origin, resulting in a decrease in received signal level when a monostatic radio-frequency (RF) system is used. For a bistatic radar configuration with space diversified receiving antennas, the shifting of the acoustic pulse makes possible the remote measurement of the horizontal wind component.

Electromagnetic and light scattering by nonspherical particles XV: Celebrating 150 years of Maxwell's electromagnetics

NASA Astrophysics Data System (ADS)

Macke, Andreas; Mishchenko, Michael I.

2016-07-01

The 15th Electromagnetic and Light Scattering Conference (ELS-XV) was held in Leipzig, Germany from 21 to 26 of June 2015 (Fig. 1). This conference built on the great success of the previous meetings held in Amsterdam (1995) [1], Helsinki (1997) [2], New York City (1998) [3], Vigo (1999), Halifax (2000) [4], Gainesville (2002) [5], Bremen (2003) [6], Salobreña (2005) [7], St. Petersburg (2006) [8], Bodrum (2007) [9], Hatfield (2008) [10], Helsinki (2010) [11], Taormina (2011) [12], and Lille [13] as well as the workshops held in Bremen (1996, 1998) and Moscow (1997). As usual, the main objective of this conference was to bring together scientists, engineers, and PhD students studying various aspects of electromagnetic scattering and to provide a relaxed atmosphere for in-depth discussion of theory, measurements, and applications. Furthermore, ELS-XV supported the United Nations "Year of Light" and celebrated the 150th anniversary of Maxwell's electromagnetics. Maxwell's paper on "A Dynamical Theory of the Electromagnetic Field" [14] was published in 1865 and has widely been acknowledged as one of the supreme achievements in the history of science.

Extension of On-Surface Radiation Condition (OSRC) theory to full-vector electromagnetic wave scattering by three-dimensional conducting, dielectric, and coated targets

NASA Astrophysics Data System (ADS)

Taflove, Allen; Umashankar, Korada R.

1993-08-01

This project introduced radiation boundary condition (RBC) and absorbing boundary condition (ABC) theory to the engineering electromagnetics community. An approximate method for obtaining the scattering of 2-D and 3-D bodies, the on-surface radiation condition (OSRC) method, was formulated and validated. RBC's and ABC's were shown to work well at points closer to scatterers than anyone had expected. Finite-difference time domain (FD-TD) methods exploiting these ABC's were pursued for applications in scattering, radiation, penetration, biomedical studies, and nonlinear optics. Multiprocessing supercomputer software was developed for FD-TD, leading to the largest scale detailed electromagnetic wave interaction models ever conducted, including entire jet fighter aircraft modeled for radar cross section (RCS) at UHF frequencies up to 500 MHz.

Solution of electromagnetic scattering problems using time domain techniques

NASA Technical Reports Server (NTRS)

Britt, Charles L.

1989-01-01

New methods are developed to calculate the electromagnetic diffraction or scattering characteristics of objects of arbitrary material and shape. The methods extend the efforts of previous researchers in the use of finite-difference and pulse response techniques. Examples are given of the scattering from infinite conducting and nonconducting cylinders, open channel, sphere, cone, cone sphere, coated disk, open boxes, and open and closed finite cylinders with axially incident waves.

Experimental measurement and theoretical modeling of microwave scattering and the structure of the sea surface influencing radar observations from space

NASA Technical Reports Server (NTRS)

Arnold, David; Kong, J. A.

1992-01-01

The electromagnetic bias is an error present in radar altimetry of the ocean due to the non-uniform reflection from wave troughs and crests. A study of the electromagnetic bias became necessary to permit error reduction in mean sea level measurements of satellite radar altimeters. Satellite radar altimeters have been used to find the upper and lower bounds for the electromagnetic bias. This report will present a theory using physical optics scattering and an empirical model of the short wave modulation to predict the electromagnetic bias. The predicted electromagnetic bias will be compared to measurements at C and Ku bands.

Investigations of electromagnetic scattering by columnar ice crystals

NASA Technical Reports Server (NTRS)

Weil, H.; Senior, T. B. A.

1976-01-01

An integral equation approach was developed to determine the scattering and absorption of electromagnetic radiation by thin walled cylinders of arbitrary cross-section and refractive index. Based on this method, extensive numerical data was presented at infrared wavelengths for hollow hexagonal cross section cylinders which simulate columnar sheath ice crystals.

Electromagnetic backscattering from a random distribution of lossy dielectric scatterers

NASA Technical Reports Server (NTRS)

Lang, R. H.

1980-01-01

Electromagnetic backscattering from a sparse distribution of discrete lossy dielectric scatterers occupying a region 5 was studied. The scatterers are assumed to have random position and orientation. Scattered fields are calculated by first finding the mean field and then by using it to define an equivalent medium within the volume 5. The scatterers are then viewed as being embedded in the equivalent medium; the distorted Born approximation is then used to find the scattered fields. This technique represents an improvement over the standard Born approximation since it takes into account the attenuation of the incident and scattered waves in the equivalent medium. The method is used to model a leaf canopy when the leaves are modeled by lossy dielectric discs.

XUV and x-ray elastic scattering of attosecond electromagnetic pulses on atoms

NASA Astrophysics Data System (ADS)

Rosmej, F. B.; Astapenko, V. A.; Lisitsa, V. S.

2017-12-01

Elastic scattering of electromagnetic pulses on atoms in XUV and soft x-ray ranges is considered for ultra-short pulses. The inclusion of the retardation term, non-dipole interaction and an efficient scattering tensor approximation allowed studying the scattering probability in dependence of the pulse duration for different carrier frequencies. Numerical calculations carried out for Mg, Al and Fe atoms demonstrate that the scattering probability is a highly nonlinear function of the pulse duration and has extrema for pulse carrier frequencies in the vicinity of the resonance-like features of the polarization charge spectrum. Closed expressions for the non-dipole correction and the angular dependence of the scattered radiation are obtained.

Influence of Spectral Transfer Processes in Compressible Low Frequency Plasma Turbulence on Scattering and Refraction of Electromagnetic Signals

DTIC Science & Technology

2015-01-01

AFRL-RY-WP-TR-2014-0230 INFLUENCE OF SPECTRAL TRANSFER PROCESSES IN COMPRESSIBLE LOW FREQUENCY PLASMA TURBULENCE ON SCATTERING AND...INFLUENCE OF SPECTRAL TRANSFER PROCESSES IN COMPRESSIBLE LOW FREQUENCY PLASMA TURBULENCE ON SCATTERING AND REFRACTION OF ELECTROMAGNETIC SIGNALS 5a...research is to analyze influence of plasma turbulence on hypersonic sensor systems and NGOTHR applications and to meet the Air Force’s ever-increasing

Finding electromagnetic and chemical enhancement factors of surface-enhanced Raman scattering.

PubMed

Dvoynenko, Mykhaylo M; Wang, Juen-Kai

2007-12-15

The authors report two methods to determine electromagnetic and chemical enhancement factors in surface-enhanced Raman scattering (SERS), which are based on saturation property and decay dynamics of photoluminescence and concurrent measurements of photoluminescence and resonance Raman scattering intensities. Considerations for experimental implementation are discussed. This study is expected to facilitate the understanding of SERS mechanisms and the advancement of the usage of SERS in chemical and biological sensor applications.

Electromagnetic wave scattering from a forest or vegetation canopy - Ongoing research at the University of Texas at Arlington

NASA Technical Reports Server (NTRS)

Karam, Mostafa A.; Amar, Faouzi; Fung, Adrian K.

1993-01-01

The Wave Scattering Research Center at the University of Texas at Arlington has developed a scattering model for forest or vegetation, based on the theory of electromagnetic-wave scattering in random media. The model generalizes the assumptions imposed by earlier models, and compares well with measurements from several forest canopies. This paper gives a description of the model. It also indicates how the model elements are integrated to obtain the scattering characteristics of different forest canopies. The scattering characteristics may be displayed in the form of polarimetric signatures, represented by like- and cross-polarized scattering coefficients, for an elliptically-polarized wave, or in the form of signal-distribution curves. Results illustrating both types of scattering characteristics are given.

Coherent light scattering of heterogeneous randomly rough films and effective medium in the theory of electromagnetic wave multiple scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berginc, G

2013-11-30

We have developed a general formalism based on Green's functions to calculate the coherent electromagnetic field scattered by a random medium with rough boundaries. The approximate expression derived makes it possible to determine the effective permittivity, which is generalised for a layer of an inhomogeneous random medium with different types of particles and bounded with randomly rough interfaces. This effective permittivity describes the coherent propagation of an electromagnetic wave in a random medium with randomly rough boundaries. We have obtained an expression, which contains the Maxwell – Garnett formula at the low-frequency limit, and the Keller formula; the latter hasmore » been proved to be in good agreement with experiments for particles whose dimensions are larger than a wavelength. (coherent light scattering)« less

User's Manual for FEM-BEM Method. 1.0

NASA Technical Reports Server (NTRS)

Butler, Theresa; Deshpande, M. D. (Technical Monitor)

2002-01-01

A user's manual for using FORTRAN code to perform electromagnetic analysis of arbitrarily shaped material cylinders using a hybrid method that combines the finite element method (FEM) and the boundary element method (BEM). In this method, the material cylinder is enclosed by a fictitious boundary and the Maxwell's equations are solved by FEM inside the boundary and by BEM outside the boundary. The electromagnetic scattering on several arbitrarily shaped material cylinders using this FORTRAN code is computed to as examples.

International Conference on Mathematical Methods in Electromagnetic Theory (MMET 2000), Volume 1 Held in Kharkov, Ukraine on September 12-15, 2000

DTIC Science & Technology

2000-09-01

Minsk, 1987 ). [13] K. S. Miller and B. Ross, An Introduction to the Fractional Calculus and Fractional Differential Equations, John Wiley & Sons, New...arbitrary cross-section", IEE Proceedings, vol. 133, Pt. H, pp. 115-121, Apr. 1986. [5] S. Eisler and Y. Leviatan, "Analysis of electromagnetic scattering...the open two-mirror resonator," Dokl. Akad. nauk URSR, Ser. A, n. 8, pp. 51-54, 1987 . Kharkov, Ukraine, VIII-th International Conference on

Extension of On-Surface Radiation Condition (OSRC) Theory to Full-Vector Electromagnetic Wave Scattering by Three-Dimensional Conducting, Dielectric, and Coated Targets

DTIC Science & Technology

1993-08-27

rever"_? if necessary and identify by block number) FIELD SUB- GROUP Electromagnetic wave scattering, radiation boundary -. ... conditions, finite...international engineering electromagnetics symposia and in related journals has risen from a level of less than 10 per year (published primarily by my group ) to...Rzpoxs and Non -Refereed Papers: 3, as follows- I. D. S. Katz, A. Taflove, J. P. Brooks and E. Harrigan, "Large-scale methods in computational

Simulation study of localization of electromagnetic waves in two-dimensional random dipolar systems.

PubMed

Wang, Ken Kang-Hsin; Ye, Zhen

2003-12-01

We study the propagation and scattering of electromagnetic waves by random arrays of dipolar cylinders in a uniform medium. A set of self-consistent equations, incorporating all orders of multiple scattering of the electromagnetic waves, is derived from first principles and then solved numerically for electromagnetic fields. For certain ranges of frequencies, spatially localized electromagnetic waves appear in such a simple but realistic disordered system. Dependence of localization on the frequency, radiation damping, and filling factor is shown. The spatial behavior of the total, coherent, and diffusive waves is explored in detail, and found to comply with a physical intuitive picture. A phase diagram characterizing localization is presented, in agreement with previous investigations on other systems.

Analysis of regolith electromagnetic scattering as constrained by high resolution Earth-based measurements of the lunar microwave emission

NASA Technical Reports Server (NTRS)

Keihm, S. J.

1983-01-01

When high resolution measurements of the phase variation of the lunar disk center brightness temperature revealed that in situ regolith electrical losses were larger than those measured on returned samples by a factor of 1.5 to 2.0 at centimeter wavelengths, the need for a refinement of the regolith model to include realistic treatment of scattering effects was identified. Two distinct scattering regimes are considered: vertial variations in dielectric constant and volume scattering due to subsurface rock fragments. Models of lunar regolith energy transport processes are now at the state for which a maximum scientific return could be realized from a lunar orbiter microwave mapping experiment. A detailed analysis, including the effects of scattering produced a set of nominal brightness temperature spectra for lunar equatorial regions, which can be used for mapping as a calibration reference for mapping variations in mineralogy and heat flow.

Electromagnetic pulse scattering by a wedge moving in a free space with relativistic velocity

NASA Astrophysics Data System (ADS)

Ciarkowski, Adam

Recently, increased interest is observed in studying scattering of electromagnetic signals by objects moving with large velocities. The velocities considered can attain relativistic values. Interesting phenomena characteristic of this class of problems were observed, in this number the Doppler shift of equiphase surfaces in the diffracted wave. Apart from new techniques elaborated to attack general scattering problems involving moving objects, specific scaterring problems are also examined. Of special interest are moving scatterers with edges. The simplest scaterrer with this property is a wedge, which in particular case reduces to a half-plane. There is a number of recent works in which diffraction of specific electromagnetic signals by these objects in motion are analyzed. In most cases time-harmonic excitation fields are being assumed. This contribution is concerned with the analysis of 2D scattering of an electromagnetic pulse by a perfectly conducting wedge moving in a free space with relativistic velocity. The exciting field is a pulsed plane-wave signal, with its envelope described by a Dirac delta function. This choice is motivated by the fact that solutions to excitation fields with different envelopes can be obtained from that found here by its integration with an appropriate weight function. In this sense this solution plays a role of a Green function. In our analysis we neglect any dispersion phenomena connected with the surrounding medium. The results herein obtained may be useful in modelling phenomena connected with the space technology. In our analysis we apply the Frame Hopping Method. In particular we first Lorentz transform the pulse signal from the laboratory frame of reference where this field is defined, to the frame where the wedge is at rest. In the latter frame we Fourier transform the resulting field to the complex frequency domain, thus arriving at the problem of time-harmonic diffraction by the wedge at rest. This problem has the exact solution, found yet by Sommerfeld. We take advantage of this solution and transform it back from complex frequency to the time domain. In this transformation both inverse Fourier transform and Felsen technique are used. Finally, the transient field obtained in the moving frame of reference is Lorentz transformed to the laboratory frame. We carry our calculations for both E- and H-field polarizations and show that the field distribution in the laboratory frame is not simply a moving image of that in the moving frame. For wedge velocities much lower than the velocity of light we reduce general expressions for the field in this frame to simpler ones.

Electromagnetic inverse scattering

NASA Technical Reports Server (NTRS)

Bojarski, N. N.

1972-01-01

A three-dimensional electromagnetic inverse scattering identity, based on the physical optics approximation, is developed for the monostatic scattered far field cross section of perfect conductors. Uniqueness of this inverse identity is proven. This identity requires complete scattering information for all frequencies and aspect angles. A nonsingular integral equation is developed for the arbitrary case of incomplete frequence and/or aspect angle scattering information. A general closed-form solution to this integral equation is developed, which yields the shape of the scatterer from such incomplete information. A specific practical radar solution is presented. The resolution of this solution is developed, yielding short-pulse target resolution radar system parameter equations. The special cases of two- and one-dimensional inverse scattering and the special case of a priori knowledge of scatterer symmetry are treated in some detail. The merits of this solution over the conventional radar imaging technique are discussed.

Understanding light scattering by a coated sphere part 2: time domain analysis.

PubMed

Laven, Philip; Lock, James A

2012-08-01

Numerical computations were made of scattering of an incident electromagnetic pulse by a coated sphere that is large compared to the dominant wavelength of the incident light. The scattered intensity was plotted as a function of the scattering angle and delay time of the scattered pulse. For fixed core and coating radii, the Debye series terms that most strongly contribute to the scattered intensity in different regions of scattering angle-delay time space were identified and analyzed. For a fixed overall radius and an increasing core radius, the first-order rainbow was observed to evolve into three separate components. The original component faded away, while the two new components eventually merged together. The behavior of surface waves generated by grazing incidence at the core/coating and coating/exterior interfaces was also examined and discussed.

Concepts in Electromagnetic Scattering for Particulate-Systems Characterization

DTIC Science & Technology

2013-04-29

scientists attended and 19 presentations were given. Specific topics included remote sensing, polarimetry , analytic and numeric electromagnetic...presentations were given. Specific topics included remote sensing, polarimetry , ana- lytic and numeric electromagnetic theory, camouflage in nature

Soft-photon emission effects and radiative corrections for electromagnetic processes at very high energies

NASA Technical Reports Server (NTRS)

Gould, R. J.

1979-01-01

Higher-order electromagnetic processes involving particles at ultrahigh energies are discussed, with particular attention given to Compton scattering with the emission of an additional photon (double Compton scattering). Double Compton scattering may have significance in the interaction of a high-energy electron with the cosmic blackbody photon gas. At high energies the cross section for double Compton scattering is large, though this effect is largely canceled by the effects of radiative corrections to ordinary Compton scattering. A similar cancellation takes place for radiative pair production and the associated radiative corrections to the radiationless process. This cancellation is related to the well-known cancellation of the infrared divergence in electrodynamics.

Electromagnetic scattering analysis of a three-dimensional-cavity-backed aperture in an infinite ground plane using a combined finite element method/method of moments approach

NASA Technical Reports Server (NTRS)

Reddy, C. J.; Deshpande, Manohar D.; Cockrell, C. R.; Beck, F. B.

1995-01-01

A combined finite element method/method of moments (FEM/MoM) approach is used to analyze the electromagnetic scattering properties of a three-dimensional-cavity-backed aperture in an infinite ground plane. The FEM is used to formulate the fields inside the cavity, and the MoM (with subdomain bases) in both spectral and spatial domains is used to formulate the fields above the ground plane. Fields in the aperture and the cavity are solved using a system of equations resulting from the combination of the FEM and the MoM. By virtue of the FEM, this combined approach is applicable to all arbitrarily shaped cavities with inhomogeneous material fillings, and because of the subdomain bases used in the MoM, the apertures can be of any arbitrary shape. This approach leads to a partly sparse and partly full symmetric matrix, which is efficiently solved using a biconjugate gradient algorithm. Numerical results are presented to validate the analysis.

Method and apparatus for aerosol particle absorption spectroscopy

DOEpatents

Campillo, Anthony J.; Lin, Horn-Bond

1983-11-15

A method and apparatus for determining the absorption spectra, and other properties, of aerosol particles. A heating beam source provides a beam of electromagnetic energy which is scanned through the region of the spectrum which is of interest. Particles exposed to the heating beam which have absorption bands within the band width of the heating beam absorb energy from the beam. The particles are also illuminated by light of a wave length such that the light is scattered by the particles. The absorption spectra of the particles can thus be determined from an analysis of the scattered light since the absorption of energy by the particles will affect the way the light is scattered. Preferably the heating beam is modulated to simplify the analysis of the scattered light. In one embodiment the heating beam is intensity modulated so that the scattered light will also be intensity modulated when the particles absorb energy. In another embodiment the heating beam passes through an interferometer and the scattered light reflects the Fourier Transform of the absorption spectra.

EM-ANIMATE: A Computer Program for Displaying and Animating Electromagnetic Near-Field and Surface-Current Solutions: Video Supplement to NASA Technical Memorandum 4539

NASA Technical Reports Server (NTRS)

Hom, Kam W.

1994-01-01

In this video, several examples of electromagnetic field and surface-current animation sequences are shown to demonstrate the visualization capabilities of the EM-ANIMATE computer program. These examples show the animation of total and scattered electric near fields from test bodies of a flat plate, a corner reflector, and a sphere. These test cases show the electric-field behavior caused by different scattering mechanisms through the animation of electromagnetic data from the EM-ANIMATE routine.

User's manual for two dimensional FDTD version TEA and TMA codes for scattering from frequency-independent dielectic materials

NASA Technical Reports Server (NTRS)

Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.

1991-01-01

The Penn State Finite Difference Time Domain Electromagnetic Scattering Code Versions TEA and TMA are two dimensional numerical electromagnetic scattering codes based upon the Finite Difference Time Domain Technique (FDTD) first proposed by Yee in 1966. The supplied version of the codes are two versions of our current two dimensional FDTD code set. This manual provides a description of the codes and corresponding results for the default scattering problem. The manual is organized into eleven sections: introduction, Version TEA and TMA code capabilities, a brief description of the default scattering geometry, a brief description of each subroutine, a description of the include files (TEACOM.FOR TMACOM.FOR), a section briefly discussing scattering width computations, a section discussing the scattering results, a sample problem set section, a new problem checklist, references and figure titles.

User's manual for two dimensional FDTD version TEA and TMA codes for scattering from frequency-independent dielectric materials

NASA Technical Reports Server (NTRS)

Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.

1991-01-01

The Penn State Finite Difference Time Domain Electromagnetic Scattering Code Versions TEA and TMA are two dimensional electromagnetic scattering codes based on the Finite Difference Time Domain Technique (FDTD) first proposed by Yee in 1966. The supplied version of the codes are two versions of our current FDTD code set. This manual provides a description of the codes and corresponding results for the default scattering problem. The manual is organized into eleven sections: introduction, Version TEA and TMA code capabilities, a brief description of the default scattering geometry, a brief description of each subroutine, a description of the include files (TEACOM.FOR TMACOM.FOR), a section briefly discussing scattering width computations, a section discussing the scattering results, a sample problem setup section, a new problem checklist, references, and figure titles.

Synthesis of resistive tapers to control scattering patterns of strips

NASA Astrophysics Data System (ADS)

Haupt, Randy L.

Scattering occurs when an electromagnetic wave impinges on an object and creates currents in that object which reradiate other electromagnetic waves. Three primary methods exist to reduce microwave scattering from an object: covering it with absorber, changing its shape, and detuning it through impedance loading. Absorbers convert unwanted electromagnetic energy into heat. An example is lining an anechoic chamber with absorbers. Changing its shape channels energy from one direction to another, changes dominant scattering centers, or causes returns from one direction to another, changes dominant scattering centers, or causes returns from various parts to coherently add and cancel the total return. Impedance loading alters the resonant frequency of an object. Absorbers have the most attractive features. They have a broad bandwidth, attenuate the return in many directions, and may be used to reduce scattering from an object after the object is designed. Before trying to control scattering from complex shapes, such as an antenna or airplane, one should try to develop methods to control scattering from simple objects. A very simple object is two dimensional strip. It is infinitely thin, has a finite width, and an infinite length. The scattering pattern of the strip depends upon its width and material composition. Varying these two factors provides a means for controlling the radar cross-section (RCS) of the strip. The goal of this thesis is to synthesize resistive tapers for the strip that produce desired bistatic scattering and backscattering patterns.

Electromagnetic properties of material coated surfaces

NASA Technical Reports Server (NTRS)

Beard, L.; Berrie, J.; Burkholder, R.; Dominek, A.; Walton, E.; Wang, N.

1989-01-01

The electromagnetic properties of material coated conducting surfaces were investigated. The coating geometries consist of uniform layers over a planar surface, irregularly shaped formations near edges and randomly positioned, electrically small, irregularly shaped formations over a surface. Techniques to measure the scattered field and constitutive parameters from these geometries were studied. The significance of the scattered field from these geometries warrants further study.

On the Concept of Random Orientation in Far-Field Electromagnetic Scattering by Nonspherical Particles

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Yurkin, Maxim A.

2017-01-01

Although the model of randomly oriented nonspherical particles has been used in a great variety of applications of far-field electromagnetic scattering, it has never been defined in strict mathematical terms. In this Letter we use the formalism of Euler rigid-body rotations to clarify the concept of statistically random particle orientations and derive its immediate corollaries in the form of most general mathematical properties of the orientation-averaged extinction and scattering matrices. Our results serve to provide a rigorous mathematical foundation for numerous publications in which the notion of randomly oriented particles and its light-scattering implications have been considered intuitively obvious.

Electromagnetic field scattering by a triangular aperture.

PubMed

Harrison, R E; Hyman, E

1979-03-15

The multiple Laplace transform has been applied to analysis and computation of scattering by a double triangular aperture. Results are obtained which match far-field intensity distributions observed in experiments. Arbitrary polarization components, as well as in-phase and quadrature-phase components, may be determined, in the transform domain, as a continuous function of distance from near to far-field for any orientation, aperture, and transformable waveform. Numerical results are obtained by application of numerical multiple inversions of the fully transformed solution.

Electromagnetic interference impact of the proposed emitters for the High Frequency Active Auroral Research Program (HAARP). Interim report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robertshaw, G.A.; Snyder, A.L.; Weiner, M.M.

1993-05-14

The proposed HAARP emitters at the Gakona (Alaska) preferred site and at the Clear AFS (Alaska) alternative site are the Ionospheric Research Instrument (IRI), the Incoherent Scatter Radar (ISR), and the Vertical Incidence Sounder(VIS). The electromagnetic interference (EMI) impact of those emitters on receiving systems in the vicinity of the sites is estimated in this study. The results are intended for use as an input to the Air Force Environmental Impact Statement as part of the Environmental Impact Analysis Process.

What are the correct ρ0(770 ) meson mass and width values?

NASA Astrophysics Data System (ADS)

Bartoš, Erik; Dubnička, Stanislav; Liptaj, Andrej; Dubničková, Anna Zuzana; Kamiński, Robert

2017-12-01

The accuracy of the Gounaris-Sakurai pion electromagnetic form factor model at the elastic region, in which just the ρ0(770 ) resonance appears, is investigated by the particular analysis of the most accurate P-wave isovector π π scattering phase shift δ11(t ) data, obtained by the Garcia-Martin-Kamiński-Peláez-Yndurain approach, and by an application of the Unitary&Analytic pion electromagnetic structure model to a description of the newest precise data on the e+e-→π+π- process.

Demonstration of Numerical Equivalence of Ensemble and Spectral Averaging in Electromagnetic Scattering by Random Particulate Media

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Dlugach, Janna M.; Zakharova, Nadezhda T.

2016-01-01

The numerically exact superposition T-matrix method is used to model far-field electromagnetic scattering by two types of particulate object. Object 1 is a fixed configuration which consists of N identical spherical particles (with N 200 or 400) quasi-randomly populating a spherical volume V having a median size parameter of 50. Object 2 is a true discrete random medium (DRM) comprising the same number N of particles randomly moving throughout V. The median particle size parameter is fixed at 4. We show that if Object 1 is illuminated by a quasi-monochromatic parallel beam then it generates a typical speckle pattern having no resemblance to the scattering pattern generated by Object 2. However, if Object 1 is illuminated by a parallel polychromatic beam with a 10 bandwidth then it generates a scattering pattern that is largely devoid of speckles and closely reproduces the quasi-monochromatic pattern generated by Object 2. This result serves to illustrate the capacity of the concept of electromagnetic scattering by a DRM to encompass fixed quasi-random particulate samples provided that they are illuminated by polychromatic light.

Resonant enhancement of Raman scattering in metamaterials with hybrid electromagnetic and plasmonic resonances

NASA Astrophysics Data System (ADS)

Guddala, Sriram; Narayana Rao, D.; Ramakrishna, S. Anantha

2016-06-01

A tri-layer metamaterial perfect absorber of light, consisting of (Al/ZnS/Al) films with the top aluminum layer patterned as an array of circular disk nanoantennas, is investigated for resonantly enhancing Raman scattering from C60 fullerene molecules deposited on the metamaterial. The metamaterial is designed to have resonant bands due to plasmonic and electromagnetic resonances at the Raman pump frequency (725 nm) as well as Stokes emission bands. The Raman scattering from C60 on the metamaterial with resonantly matched bands is measured to be enhanced by an order of magnitude more than C60 on metamaterials with off-resonant absorption bands peaking at 1090 nm. The Raman pump is significantly enhanced due to the resonance with a propagating surface plasmon band, while the highly impedance-matched electromagnetic resonance is expected to couple out the Raman emission efficiently. The nature and hybridization of the plasmonic and electromagnetic resonances to form compound resonances are investigated by numerical simulations.

Inhibition of electron thermal conduction by electromagnetic instabilities. [in stellar coronas

NASA Technical Reports Server (NTRS)

Levinson, Amir; Eichler, David

1992-01-01

Heat flux inhibition by electromagnetic instabilities in a hot magnetized plasma is investigated. Low-frequency electromagnetic waves become unstable due to anisotropy of the electron distribution function. The chaotic magnetic field thus generated scatters the electrons with a specific effective mean free path. Saturation of the instability due to wave-wave interaction, nonlinear scattering, wave propagation, and collisional damping is considered. The effective mean free path is found self-consistently, using a simple model to estimate saturation level and scattering, and is shown to decrease with the temperature gradient length. The results, limited to the assumptions of the model, are applied to astrophysical systems. For some interstellar clouds the instability is found to be important. Collisional damping stabilizes the plasma, and the heat conduction can be dominated by superthermal electrons.

Weak scattering of scalar and electromagnetic random fields

NASA Astrophysics Data System (ADS)

Tong, Zhisong

This dissertation encompasses several studies relating to the theory of weak potential scattering of scalar and electromagnetic random, wide-sense statistically stationary fields from various types of deterministic or random linear media. The proposed theory is largely based on the first Born approximation for potential scattering and on the angular spectrum representation of fields. The main focus of the scalar counterpart of the theory is made on calculation of the second-order statistics of scattered light fields in cases when the scattering medium consists of several types of discrete particles with deterministic or random potentials. It is shown that the knowledge of the correlation properties for the particles of the same and different types, described with the newly introduced pair-scattering matrix, is crucial for determining the spectral and coherence states of the scattered radiation. The approach based on the pair-scattering matrix is then used for solving an inverse problem of determining the location of an "alien" particle within the scattering collection of "normal" particles, from several measurements of the spectral density of scattered light. Weak scalar scattering of light from a particulate medium in the presence of optical turbulence existing between the scattering centers is then approached using the combination of the Born's theory for treating the light interaction with discrete particles and the Rytov's theory for light propagation in extended turbulent medium. It is demonstrated how the statistics of scattered radiation depend on scattering potentials of particles and the power spectra of the refractive index fluctuations of turbulence. This theory is of utmost importance for applications involving atmospheric and oceanic light transmission. The second part of the dissertation includes the theoretical procedure developed for predicting the second-order statistics of the electromagnetic random fields, such as polarization and linear momentum, scattered from static media. The spatial distribution of these properties of scattered fields is shown to be substantially dependent on the correlation and polarization properties of incident fields and on the statistics of the refractive index distribution within the scatterers. Further, an example is considered which illustrates the usefulness of the electromagnetic scattering theory of random fields in the case when the scattering medium is a thin bio-tissue layer with the prescribed power spectrum of the refractive index fluctuations. The polarization state of the scattered light is shown to be influenced by correlation and polarization states of the illumination as well as by the particle size distribution of the tissue slice.

Microwave imaging by three-dimensional Born linearization of electromagnetic scattering

NASA Astrophysics Data System (ADS)

Caorsi, S.; Gragnani, G. L.; Pastorino, M.

1990-11-01

An approach to microwave imaging is proposed that uses a three-dimensional vectorial form of the Born approximation to linearize the equation of electromagnetic scattering. The inverse scattering problem is numerically solved for three-dimensional geometries by means of the moment method. A pseudoinversion algorithm is adopted to overcome ill conditioning. Results show that the method is well suited for qualitative imaging purposes, while its capability for exactly reconstructing the complex dielectric permittivity is affected by the limitations inherent in the Born approximation and in ill conditioning.

The Harp probe - An in situ Bragg scattering sensor

NASA Technical Reports Server (NTRS)

Mollo-Christensen, E.; Huang, N. E.; Long, S. R.; Bliven, L. F.

1984-01-01

A wave sensor, consisting of parallel, evenly spaced capacitance wires, whose output is the sum of the water surface deflections at the wires, has been built and tested in a wave tank. The probe output simulates Bragg scattering of electromagnetic waves from a water surface with waves; it can be used to simulate electromagnetic probing of the sea surface by radar. The study establishes that the wave probe, called the 'Harp' for short, will simulate Bragg scattering and that it can also be used to study nonlinear wave processes.

Concentric layered Hermite scatterers

NASA Astrophysics Data System (ADS)

Astheimer, Jeffrey P.; Parker, Kevin J.

2018-05-01

The long wavelength limit of scattering from spheres has a rich history in optics, electromagnetics, and acoustics. Recently it was shown that a common integral kernel pertains to formulations of weak spherical scatterers in both acoustics and electromagnetic regimes. Furthermore, the relationship between backscattered amplitude and wavenumber k was shown to follow power laws higher than the Rayleigh scattering k2 power law, when the inhomogeneity had a material composition that conformed to a Gaussian weighted Hermite polynomial. Although this class of scatterers, called Hermite scatterers, are plausible, it may be simpler to manufacture scatterers with a core surrounded by one or more layers. In this case the inhomogeneous material property conforms to a piecewise continuous constant function. We demonstrate that the necessary and sufficient conditions for supra-Rayleigh scattering power laws in this case can be stated simply by considering moments of the inhomogeneous function and its spatial transform. This development opens an additional path for construction of, and use of scatterers with unique power law behavior.

Electromagnetic radiation from filamentary sources in the presence of axially magnetized cylindrical plasma scatterers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Es’kin, V. A.; Ivoninsky, A. V.; Kudrin, A. V., E-mail: kud@rf.unn.ru

Electromagnetic radiation from filamentary electric-dipole and magnetic-current sources of infinite length in the presence of gyrotropic cylindrical scatterers in the surrounding free space is studied. The scatterers are assumed to be infinitely long, axially magnetized circular plasma columns parallel to the axis of the filamentary source. The field and the radiation pattern of each source are calculated in the case where the source frequency is equal to one of the surface plasmon resonance frequencies of the cylindrical scatterers. It is shown that the presence of even a single resonant magnetized plasma scatterer of small electrical radius or a few suchmore » scatterers significantly affects the total fields of the filamentary sources, so that their radiation patterns become essentially different from those in the absence of scatterers or the presence of isotropic scatterers of the same shape and size. It is concluded that the radiation characteristics of the considered sources can efficiently be controlled using their resonance interaction with the neighboring gyrotropic scatterers.« less

An isogeometric boundary element method for electromagnetic scattering with compatible B-spline discretizations

NASA Astrophysics Data System (ADS)

Simpson, R. N.; Liu, Z.; Vázquez, R.; Evans, J. A.

2018-06-01

We outline the construction of compatible B-splines on 3D surfaces that satisfy the continuity requirements for electromagnetic scattering analysis with the boundary element method (method of moments). Our approach makes use of Non-Uniform Rational B-splines to represent model geometry and compatible B-splines to approximate the surface current, and adopts the isogeometric concept in which the basis for analysis is taken directly from CAD (geometry) data. The approach allows for high-order approximations and crucially provides a direct link with CAD data structures that allows for efficient design workflows. After outlining the construction of div- and curl-conforming B-splines defined over 3D surfaces we describe their use with the electric and magnetic field integral equations using a Galerkin formulation. We use Bézier extraction to accelerate the computation of NURBS and B-spline terms and employ H-matrices to provide accelerated computations and memory reduction for the dense matrices that result from the boundary integral discretization. The method is verified using the well known Mie scattering problem posed over a perfectly electrically conducting sphere and the classic NASA almond problem. Finally, we demonstrate the ability of the approach to handle models with complex geometry directly from CAD without mesh generation.

Full-wave Nonlinear Inverse Scattering for Acoustic and Electromagnetic Breast Imaging

NASA Astrophysics Data System (ADS)

Haynes, Mark Spencer

Acoustic and electromagnetic full-wave nonlinear inverse scattering techniques are explored in both theory and experiment with the ultimate aim of noninvasively mapping the material properties of the breast. There is evidence that benign and malignant breast tissue have different acoustic and electrical properties and imaging these properties directly could provide higher quality images with better diagnostic certainty. In this dissertation, acoustic and electromagnetic inverse scattering algorithms are first developed and validated in simulation. The forward solvers and optimization cost functions are modified from traditional forms in order to handle the large or lossy imaging scenes present in ultrasonic and microwave breast imaging. An antenna model is then presented, modified, and experimentally validated for microwave S-parameter measurements. Using the antenna model, a new electromagnetic volume integral equation is derived in order to link the material properties of the inverse scattering algorithms to microwave S-parameters measurements allowing direct comparison of model predictions and measurements in the imaging algorithms. This volume integral equation is validated with several experiments and used as the basis of a free-space inverse scattering experiment, where images of the dielectric properties of plastic objects are formed without the use of calibration targets. These efforts are used as the foundation of a solution and formulation for the numerical characterization of a microwave near-field cavity-based breast imaging system. The system is constructed and imaging results of simple targets are given. Finally, the same techniques are used to explore a new self-characterization method for commercial ultrasound probes. The method is used to calibrate an ultrasound inverse scattering experiment and imaging results of simple targets are presented. This work has demonstrated the feasibility of quantitative microwave inverse scattering by way of a self-consistent characterization formalism, and has made headway in the same area for ultrasound.

User's manual for three dimensional FDTD version C code for scattering from frequency-independent dielectric and magnetic materials

NASA Technical Reports Server (NTRS)

Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.

1991-01-01

The Penn State Finite Difference Time Domain Electromagnetic Scattering Code Version C is a three dimensional numerical electromagnetic scattering code based upon the Finite Difference Time Domain Technique (FDTD). The supplied version of the code is one version of our current three dimensional FDTD code set. This manual provides a description of the code and corresponding results for several scattering problems. The manual is organized into fourteen sections: introduction, description of the FDTD method, operation, resource requirements, Version C code capabilities, a brief description of the default scattering geometry, a brief description of each subroutine, a description of the include file (COMMONC.FOR), a section briefly discussing Radar Cross Section (RCS) computations, a section discussing some scattering results, a sample problem setup section, a new problem checklist, references and figure titles.

User's manual for three dimensional FDTD version D code for scattering from frequency-dependent dielectric and magnetic materials

NASA Technical Reports Server (NTRS)

Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.

1991-01-01

The Penn State Finite Difference Time Domain Electromagnetic Scattering Code Version D is a three dimensional numerical electromagnetic scattering code based upon the Finite Difference Time Domain Technique (FDTD). The supplied version of the code is one version of our current three dimensional FDTD code set. This manual provides a description of the code and corresponding results for several scattering problems. The manual is organized into fourteen sections: introduction, description of the FDTD method, operation, resource requirements, Version D code capabilities, a brief description of the default scattering geometry, a brief description of each subroutine, a description of the include file (COMMOND.FOR), a section briefly discussing Radar Cross Section (RCS) computations, a section discussing some scattering results, a sample problem setup section, a new problem checklist, references and figure titles.

User's manual for three dimensional FDTD version A code for scattering from frequency-independent dielectric materials

NASA Technical Reports Server (NTRS)

Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.

1992-01-01

The Penn State Finite Difference Time Domain (FDTD) Electromagnetic Scattering Code Version A is a three dimensional numerical electromagnetic scattering code based on the Finite Difference Time Domain technique. The supplied version of the code is one version of our current three dimensional FDTD code set. The manual provides a description of the code and the corresponding results for the default scattering problem. The manual is organized into 14 sections: introduction, description of the FDTD method, operation, resource requirements, Version A code capabilities, a brief description of the default scattering geometry, a brief description of each subroutine, a description of the include file (COMMONA.FOR), a section briefly discussing radar cross section (RCS) computations, a section discussing the scattering results, a sample problem setup section, a new problem checklist, references, and figure titles.

User's manual for three dimensional FDTD version C code for scattering from frequency-independent dielectric and magnetic materials

NASA Technical Reports Server (NTRS)

Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.

1992-01-01

The Penn State Finite Difference Time Domain Electromagnetic Scattering Code Version C is a three-dimensional numerical electromagnetic scattering code based on the Finite Difference Time Domain (FDTD) technique. The supplied version of the code is one version of our current three-dimensional FDTD code set. The manual given here provides a description of the code and corresponding results for several scattering problems. The manual is organized into 14 sections: introduction, description of the FDTD method, operation, resource requirements, Version C code capabilities, a brief description of the default scattering geometry, a brief description of each subroutine, a description of the include file (COMMONC.FOR), a section briefly discussing radar cross section computations, a section discussing some scattering results, a new problem checklist, references, and figure titles.

User's manual for three dimensional FDTD version B code for scattering from frequency-dependent dielectric materials

NASA Technical Reports Server (NTRS)

Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.

1991-01-01

The Penn State Finite Difference Time Domain Electromagnetic Scattering Code Version B is a three dimensional numerical electromagnetic scattering code based upon the Finite Difference Time Domain Technique (FDTD). The supplied version of the code is one version of our current three dimensional FDTD code set. This manual provides a description of the code and corresponding results for several scattering problems. The manual is organized into fourteen sections: introduction, description of the FDTD method, operation, resource requirements, Version B code capabilities, a brief description of the default scattering geometry, a brief description of each subroutine, a description of the include file (COMMONB.FOR), a section briefly discussing Radar Cross Section (RCS) computations, a section discussing some scattering results, a sample problem setup section, a new problem checklist, references and figure titles.

Electromagnetic ray tracing model for line structures.

PubMed

Tan, C B; Khoh, A; Yeo, S H

2008-03-17

In this paper, a model for electromagnetic scattering of line structures is established based on high frequency approximation approach - ray tracing. This electromagnetic ray tracing (ERT) model gives the advantage of identifying each physical field that contributes to the total solution of the scattering phenomenon. Besides the geometrical optics field, different diffracted fields associated with the line structures are also discussed and formulated. A step by step addition of each electromagnetic field is given to elucidate the causes of a disturbance in the amplitude profile. The accuracy of the ERT model is also discussed by comparing with the reference finite difference time domain (FDTD) solution, which shows a promising result for a single polysilicon line structure with width of as narrow as 0.4 wavelength.

The SEM description of interaction of a transient electromagnetic wave with an object

NASA Technical Reports Server (NTRS)

Pearson, L. W.; Wilton, D. R.

1980-01-01

The singularity expansion method (SEM), proposed as a means for determining and representing the transient surface current density induced on a scatterer by a transient electromagnetic wave is described. The resulting mathematical description of the transient surface current on the object is discussed. The data required to represent the electromagnetic scattering properties of a given object are examined. Experimental methods which were developed for the determination of the SEM description are discussed. The feasibility of characterizing the surface current induced on aircraft flying in proximity to a lightning stroke by way of SEM is examined.

Strain-induced three-photon effects

NASA Astrophysics Data System (ADS)

Jeong, Jae-Woo; Shin, Sung-Chul; Lyubchanskii, I. L.; Varyukhin, V. N.

2000-11-01

Strain-induced three-photon effects such as optical second-harmonic generation and hyper-Rayleigh light scattering, characterized by electromagnetic radiation at the double frequency of an incident light, are phenomenologically investigated by adopting a nonlinear photoelastic interaction. The relations between the strain and the nonlinear optical susceptibility for crystal surfaces with point symmetries of 4mm and 3m are described by a symmetry analysis of the nonlinear photoelastic tensor. We theoretically demonstrate a possibility of determining the strain components by measuring the rotational anisotropy of radiation at the second-harmonic frequency. Hyper-Rayleigh light scattering by dislocation strain is also described using a nonlinear photoelastic tensor. The angular dependencies of light scattered at the double frequency of an incident light for different scattering geometries are analyzed.

User's manual for three dimensional FDTD version B code for scattering from frequency-dependent dielectric materials

NASA Technical Reports Server (NTRS)

Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.

1992-01-01

The Penn State Finite Difference Time Domain Electromagnetic Code Version B is a three dimensional numerical electromagnetic scattering code based upon the Finite Difference Time Domain Technique (FDTD). The supplied version of the code is one version of our current three dimensional FDTD code set. This manual provides a description of the code and corresponding results for several scattering problems. The manual is organized into 14 sections: introduction, description of the FDTD method, operation, resource requirements, Version B code capabilities, a brief description of the default scattering geometry, a brief description of each subroutine, a description of the include file, a discussion of radar cross section computations, a discussion of some scattering results, a sample problem setup section, a new problem checklist, references and figure titles.

10 years of Elsevier/JQSRT awards

NASA Astrophysics Data System (ADS)

Stoop, José; Bernath, Peter F.; Mengüç, M. Pinar; Mishchenko, Michael I.; Rothman, Laurence S.

2017-10-01

The Elsevier award program administered by the Editorial Board of the Journal of Quantitative Spectroscopy and Radiative Transfer (JQSRT) was conceived in June of 2006 at the 9th Electromagnetic and Light Scattering Conference in St. Petersburg, Russia. Initially the program included three annual Elsevier/JQSRT awards for exceptional early-career scientists working in the main research fields covered by JQSRT: quantitative spectroscopy, radiative transfer, and electromagnetic scattering. In June of 2010 at the 12th Electromagnetic and Light Scattering Conference in Helsinki, Finland, it was decided to expand the award program to include three biennial Elsevier awards intended to celebrate fundamental life-time achievements of internationally recognized leaders in the same research fields. Finally, in 2013 the Elsevier award program was augmented to include a fourth annual early-career award in the category of atmospheric radiation and remote sensing.

Damping and scattering of electromagnetic waves by small ferrite spheres suspended in an insulator

NASA Technical Reports Server (NTRS)

Englert, Gerald W.

1992-01-01

The intentional degradation of electromagnetic waves by their penetration into a media comprised of somewhat sparsely distributed energy absorbing ferrite spheres suspended in an electrical insulator is investigated. Results are presented in terms of generalized parameters involving wave length and sphere size, sphere resistivity, permeability, and spacing; their influence on dissipation of wave power by eddy currents, magnetic hysteresis, and scattering is shown.

Advanced electromagnetic methods for aerospace vehicles

NASA Technical Reports Server (NTRS)

Balanis, Constantine A.; Sun, Weimin; El-Sharawy, El-Budawy; Aberle, James T.; Birtcher, Craig R.; Peng, Jian; Tirkas, Panayiotis A.

1992-01-01

The Advanced Helicopter Electromagnetics (AHE) Industrial Associates Program continues its research on variety of main topics identified and recommended by the Advisory Task Force of the program. The research activities center on issues that advance technology related to helicopter electromagnetics. While most of the topics are a continuation of previous works, special effort has been focused on some of the areas due to recommendations from the last annual conference. The main topics addressed in this report are: composite materials, and antenna technology. The area of composite materials continues getting special attention in this period. The research has focused on: (1) measurements of the electrical properties of low-conductivity materials; (2) modeling of material discontinuity and their effects on the scattering patterns; (3) preliminary analysis on interaction of electromagnetic fields with multi-layered graphite fiberglass plates; and (4) finite difference time domain (FDTD) modeling of fields penetration through composite panels of a helicopter.

Determination of concrete cover thickness in a reinforced concrete pillar by observation of the scattered electromagnetic field

NASA Astrophysics Data System (ADS)

Di Gregorio, Pietro Paolo; Frezza, Fabrizio; Mangini, Fabio; Pajewski, Lara

2017-04-01

The electromagnetic scattered field by a reinforced concrete structure is calculated by means of frequency-domain numerical simulations and by making use of the scattered-field formulation. The concrete pillar, used as supporting architectural element, is modelled as a parallelepiped shell made of concrete material inside which are present steel bars. In order to make the model simpler, the steel bars are supposed running parallel to the air-pillar interface. To excite the model, a linearly-polarized plane wave impinging normally with respect to the pillars surface, is adopted. We consider two different polarizations in order to determine the most useful in terms of scattered-field sensitivity. Moreover, a preliminary frequency sweep allows us to choose the most suitable operating frequency depending on the dimensions of the pillar cross-section, the steel bars cross-section and the concrete cover. All the three components of the scattered field are monitored along a line just above the interface air-pillar. The electromagnetic properties of the materials employed in this study are present in the literature and, since a frequency-domain technique is adopted, no further approximation is needed. The results obtained for different values of the concrete cover are compared, with the goal of determining the scattered field dependence on the concrete cover thickness. Considering different concrete cover thicknesses, we want to provide an electromagnetic method to obtain this useful parameter by observation of the scattered electromagnetic field. One of the practical applications of this study in the field of Civil Engineering may be the use of ground penetrating radar (GPR) techniques to monitor the thickness of the concrete that separates the metal bars embedded in the pillar from the outer surface. A correct distance is useful because the concrete cover serves as a protection against external agents avoiding corrosion of the bars that might prejudice the reinforced concrete; it ensures also an optimal transmission and distribution of the adhesion forces in the pillar. Acknowledgement This work is a contribution to COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar" (www.GPRadar.eu, www.cost.eu).

Homogeneous illusion device exhibiting transformed and shifted scattering effect

NASA Astrophysics Data System (ADS)

Mei, Jin-Shuo; Wu, Qun; Zhang, Kuang; He, Xun-Jun; Wang, Yue

2016-06-01

Based on the theory of transformation optics, a type of homogeneous illusion device exhibiting transformed and shifted scattering effect is proposed in this paper. The constitutive parameters of the proposed device are derived, and full-wave simulations are performed to validate the electromagnetic properties of transformed and shifted scattering effect. The simulation results show that the proposed device not only can visually shift the image of target in two dimensions, but also can visually transform the shape of target. It is expected that such homogeneous illusion device could possess potential applications in military camouflage and other field of electromagnetic engineering.

A new numerically stable implementation of the T-matrix method for electromagnetic scattering by spheroidal particles

NASA Astrophysics Data System (ADS)

Somerville, W. R. C.; Auguié, B.; Le Ru, E. C.

2013-07-01

We propose, describe, and demonstrate a new numerically stable implementation of the extended boundary-condition method (EBCM) to compute the T-matrix for electromagnetic scattering by spheroidal particles. Our approach relies on the fact that for many of the EBCM integrals in the special case of spheroids, a leading part of the integrand integrates exactly to zero, which causes catastrophic loss of precision in numerical computations. This feature was in fact first pointed out by Waterman in the context of acoustic scattering and electromagnetic scattering by infinite cylinders. We have recently studied it in detail in the case of electromagnetic scattering by particles. Based on this study, the principle of our new implementation is therefore to compute all the integrands without the problematic part to avoid the primary cause of loss of precision. Particular attention is also given to choosing the algorithms that minimise loss of precision in every step of the method, without compromising on speed. We show that the resulting implementation can efficiently compute in double precision arithmetic the T-matrix and therefore optical properties of spheroidal particles to a high precision, often down to a remarkable accuracy (10-10 relative error), over a wide range of parameters that are typically considered problematic. We discuss examples such as high-aspect ratio metallic nanorods and large size parameter (≈35) dielectric particles, which had been previously modelled only using quadruple-precision arithmetic codes.

Electromagnetic topology: Characterization of internal electromagnetic coupling

NASA Technical Reports Server (NTRS)

Parmantier, J. P.; Aparicio, J. P.; Faure, F.

1991-01-01

The main principles are presented of a method dealing with the resolution of electromagnetic internal problems: Electromagnetic Topology. A very interesting way is to generalize the multiconductor transmission line network theory to the basic equation of the Electromagnetic Topology: the BLT equation. This generalization is illustrated by the treatment of an aperture as a four port junction. Analytical and experimental derivations of the scattering parameters are presented. These concepts are used to study the electromagnetic coupling in a scale model of an aircraft, and can be seen as a convenient means to test internal electromagnetic interference.

Analysis of the Hessian for Inverse Scattering Problems. Part 3. Inverse Medium Scattering of Electromagnetic Waves in Three Dimensions

DTIC Science & Technology

2012-08-01

small data noise and model error, the discrete Hessian can be approximated by a low-rank matrix. This in turn enables fast solution of an appropriately...implication of the compactness of the Hessian is that for small data noise and model error, the discrete Hessian can be approximated by a low-rank matrix. This...probability distribution is given by the inverse of the Hessian of the negative log likelihood function. For Gaussian data noise and model error, this

Electromagnetic Scattering from Arbitrarily Shaped Aperture Backed by Rectangular Cavity Recessed in Infinite Ground Plane

NASA Technical Reports Server (NTRS)

Cockrell, C. R.; Beck, Fred B.

1997-01-01

The electromagnetic scattering from an arbitrarily shaped aperture backed by a rectangular cavity recessed in an infinite ground plane is analyzed by the integral equation approach. In this approach, the problem is split into two parts: exterior and interior. The electromagnetic fields in the exterior part are obtained from an equivalent magnetic surface current density assumed to be flowing over the aperture and backed by an infinite ground plane. The electromagnetic fields in the interior part are obtained in terms of rectangular cavity modal expansion functions. The modal amplitudes of cavity modes are determined by enforcing the continuity of the electric field across the aperture. The integral equation with the aperture magnetic current density as an unknown is obtained by enforcing the continuity of magnetic fields across the aperture. The integral equation is then solved for the magnetic current density by the method of moments. The electromagnetic scattering properties of an aperture backed by a rectangular cavity are determined from the magnetic current density. Numerical results on the backscatter radar cross-section (RCS) patterns of rectangular apertures backed by rectangular cavities are compared with earlier published results. Also numerical results on the backscatter RCS patterns of a circular aperture backed by a rectangular cavity are presented.

Electromagnetic Scattering by a Morphologically Complex Object: Fundamental Concepts and Common Misconceptions

NASA Technical Reports Server (NTRS)

Mischenko, Michael I.; Travis, Larry D.; Cairns, Brian; Tishkovets, Victor P.; Dlugach, Janna M.; Rosenbush, Vera K.; Kiselev, Nikolai N.

2011-01-01

Following Keller(Proc Symp Appl Math 1962;13:227:46), we classify all theoretical treatments of electromagnetic scattering by a morphologically complex object into first- principle (or "honest" in Keller s terminology) and phenomenological (or "dishonest") categories. This helps us identify, analyze, and dispel several profound misconceptions widespread in the discipline of electromagnetic scattering by solitary particles and discrete random media. Our goal is not to call for a complete renunciation of phenomenological approaches but rather to encourage a critical and careful evaluation of their actual origin, virtues, and limitations. In other words, we do not intend to deter creative thinking in terms of phenomenological short-cuts, but we do want to raise awareness when we stray (often for practical reasons) from the fundamentals. The main results and conclusions are illustrated by numerically-exact data based on direct numerical solutions of the macroscopic Maxwell equations.

Modeling of Electromagnetic Scattering by Discrete and Discretely Heterogeneous Random Media by Using Numerically Exact Solutions of the Maxwell Equations

NASA Technical Reports Server (NTRS)

Dlugach, Janna M.; Mishchenko, Michael I.

2017-01-01

In this paper, we discuss some aspects of numerical modeling of electromagnetic scattering by discrete random medium by using numerically exact solutions of the macroscopic Maxwell equations. Typical examples of such media are clouds of interstellar dust, clouds of interplanetary dust in the Solar system, dusty atmospheres of comets, particulate planetary rings, clouds in planetary atmospheres, aerosol particles with numerous inclusions and so on. Our study is based on the results of extensive computations of different characteristics of electromagnetic scattering obtained by using the superposition T-matrix method which represents a direct computer solver of the macroscopic Maxwell equations for an arbitrary multisphere configuration. As a result, in particular, we clarify the range of applicability of the low-density theories of radiative transfer and coherent backscattering as well as of widely used effective-medium approximations.

Forward and inverse models of electromagnetic scattering from layered media with rough interfaces

NASA Astrophysics Data System (ADS)

Tabatabaeenejad, Seyed Alireza

This work addresses the problem of electromagnetic scattering from layered dielectric structures with rough boundaries and the associated inverse problem of retrieving the subsurface parameters of the structure using the scattered field. To this end, a forward scattering model based on the Small Perturbation Method (SPM) is developed to calculate the first-order spectral-domain bistatic scattering coefficients of a two-layer rough surface structure. SPM requires the boundaries to be slightly rough compared to the wavelength, but to understand the range of applicability of this method in scattering from two-layer rough surfaces, its region of validity is investigated by comparing its output with that of a first principle solver that does not impose roughness restrictions. The Method of Moments (MoM) is used for this purpose. Finally, for retrieval of the model parameters of the layered structure using scattered field, an inversion scheme based on the Simulated Annealing method is investigated and a strategy is proposed to address convergence to local minimum.

Analysis of 4He+40Ca and 4He+44Ti scattering using different optical model potentials

NASA Astrophysics Data System (ADS)

Ibraheem, Awad A.

2016-09-01

Elastic scattering of 4He+40Ca and 4He+44Ti reactions at backward angles has been analyzed using two differentmodels, microscopic and semimicroscopic folding potentials. The derived real potentials supplemented with phenomenological Woods-Saxon imaginary potentials, provide good agreement with the experimental data at energy E c.m. = 21.8 MeV without need to renormalize the potentials. Coupledchannels calculations are used to extract the inelastic scattering cross section to the low-lying state 2+ (1.083 MeV) of 44Ti. The deformation length is obtained and compared with the electromagnetic measurement values as well as those obtained from previous studies.

Computation of tightly-focused laser beams in the FDTD method

PubMed Central

Çapoğlu, İlker R.; Taflove, Allen; Backman, Vadim

2013-01-01

We demonstrate how a tightly-focused coherent TEMmn laser beam can be computed in the finite-difference time-domain (FDTD) method. The electromagnetic field around the focus is decomposed into a plane-wave spectrum, and approximated by a finite number of plane waves injected into the FDTD grid using the total-field/scattered-field (TF/SF) method. We provide an error analysis, and guidelines for the discrete approximation. We analyze the scattering of the beam from layered spaces and individual scatterers. The described method should be useful for the simulation of confocal microscopy and optical data storage. An implementation of the method can be found in our free and open source FDTD software (“Angora”). PMID:23388899

Computation of tightly-focused laser beams in the FDTD method.

PubMed

Capoğlu, Ilker R; Taflove, Allen; Backman, Vadim

2013-01-14

We demonstrate how a tightly-focused coherent TEMmn laser beam can be computed in the finite-difference time-domain (FDTD) method. The electromagnetic field around the focus is decomposed into a plane-wave spectrum, and approximated by a finite number of plane waves injected into the FDTD grid using the total-field/scattered-field (TF/SF) method. We provide an error analysis, and guidelines for the discrete approximation. We analyze the scattering of the beam from layered spaces and individual scatterers. The described method should be useful for the simulation of confocal microscopy and optical data storage. An implementation of the method can be found in our free and open source FDTD software ("Angora").

MOM3D method of moments code theory manual

NASA Technical Reports Server (NTRS)

Shaeffer, John F.

1992-01-01

MOM3D is a FORTRAN algorithm that solves Maxwell's equations as expressed via the electric field integral equation for the electromagnetic response of open or closed three dimensional surfaces modeled with triangle patches. Two joined triangles (couples) form the vector current unknowns for the surface. Boundary conditions are for perfectly conducting or resistive surfaces. The impedance matrix represents the fundamental electromagnetic interaction of the body with itself. A variety of electromagnetic analysis options are possible once the impedance matrix is computed including backscatter radar cross section (RCS), bistatic RCS, antenna pattern prediction for user specified body voltage excitation ports, RCS image projection showing RCS scattering center locations, surface currents excited on the body as induced by specified plane wave excitation, and near field computation for the electric field on or near the body.

Microwave analog experiments on optically soft spheroidal scatterers with weak electromagnetic signature

NASA Astrophysics Data System (ADS)

Saleh, H.; Charon, J.; Dauchet, J.; Tortel, H.; Geffrin, J.-M.

2017-07-01

Light scattering by optically soft particles is being theoretically investigated in many radiative studies. An interest is growing up to develop approximate methods when the resolution of Maxwell's equations is impractical due to time and/or memory size problems with objects of complex geometries. The participation of experimental studies is important to assess novel approximations when no reference solution is available. The microwave analogy represents an efficient solution to perform such electromagnetic measurements in controlled conditions. In this paper, we take advantage of the particular features of our microwave device to present an extensive experimental study on the electromagnetic scattering by spheroidal particles analogs with low refractive indices, as a first step toward the assessment of micro-organisms with low refractive index and heterogeneities. The spheroidal analogs are machined from a low density material and they mimic soft particles of interest to the light scattering community. The measurements are confronted to simulations obtained with Finite Element Method and T-Matrix method. A good agreement is obtained even with refractive index as low as 1.13. Scattered signals of low intensities are correctly measured and the position of the targets is precisely controlled. The forward scattering measurements show high sensitivity to noise and require careful extraction. The configuration of the measurement device reveals different technical requirements between forward and backward scattering directions. The results open interesting perspectives about novel measurement procedures as well as about the use of high prototyping technologies to manufacture analogs of precise refractive indices and shapes.

The role of plasma density scale length on the laser pulse propagation and scattering in relativistic regime

NASA Astrophysics Data System (ADS)

Pishdast, Masoud; Ghasemi, Seyed Abolfazl; Yazdanpanah, Jamal Aldin

2017-10-01

The role of plasma density scale length on two short and long laser pulse propagation and scattering in under dense plasma have been investigated in relativistic regime using 1 D PIC simulation. In our simulation, different density scale lengths and also two short and long pulse lengths with temporal pulse duration τL = 60 fs and τL = 300 fs , respectively have been used. It is found that laser pulse length and density scale length have considerable effects on the energetic electron generation. The analysis of total radiation spectrum reveals that, for short laser pulses and with reducing density scale length, more unstable electromagnetic modes grow and strong longitudinal electric field generates which leads to the generation of more energetic plasma particles. Meanwhile, the dominant scattering mechanism is Raman scattering and tends to Thomson scattering for longer laser pulse.

Three-Dimensional Electromagnetic Scattering from Layered Media with Rough Interfaces for Subsurface Radar Remote Sensing

NASA Astrophysics Data System (ADS)

Duan, Xueyang

The objective of this dissertation is to develop forward scattering models for active microwave remote sensing of natural features represented by layered media with rough interfaces. In particular, soil profiles are considered, for which a model of electromagnetic scattering from multilayer rough surfaces with or without buried random media is constructed. Starting from a single rough surface, radar scattering is modeled using the stabilized extended boundary condition method (SEBCM). This method solves the long-standing instability issue of the classical EBCM, and gives three-dimensional full wave solutions over large ranges of surface roughnesses with higher computational efficiency than pure numerical solutions, e.g., method of moments (MoM). Based on this single surface solution, multilayer rough surface scattering is modeled using the scattering matrix approach and the model is used for a comprehensive sensitivity analysis of the total ground scattering as a function of layer separation, subsurface statistics, and sublayer dielectric properties. The buried inhomogeneities such as rocks and vegetation roots are considered for the first time in the forward scattering model. Radar scattering from buried random media is modeled by the aggregate transition matrix using either the recursive transition matrix approach for spherical or short-length cylindrical scatterers, or the generalized iterative extended boundary condition method we developed for long cylinders or root-like cylindrical clusters. These approaches take the field interactions among scatterers into account with high computational efficiency. The aggregate transition matrix is transformed to a scattering matrix for the full solution to the layered-medium problem. This step is based on the near-to-far field transformation of the numerical plane wave expansion of the spherical harmonics and the multipole expansion of plane waves. This transformation consolidates volume scattering from the buried random medium with the scattering from layered structure in general. Combined with scattering from multilayer rough surfaces, scattering contributions from subsurfaces and vegetation roots can be then simulated. Solutions of both the rough surface scattering and random media scattering are validated numerically, experimentally, or both. The experimental validations have been carried out using a laboratory-based transmit-receive system for scattering from random media and a new bistatic tower-mounted radar system for field-based surface scattering measurements.

Electromagnetic scattering and absorption by thin walled dielectric cylinders with application to ice crystals

NASA Technical Reports Server (NTRS)

Senior, T. B. A.; Weil, H.

1977-01-01

Important in the atmospheric heat balance are the reflection, transmission, and absorption of visible and infrared radiation by clouds and polluted atmospheres. Integral equations are derived to evaluate the scattering and absorption of electromagnetic radiation from thin cylindrical dielectric shells of arbitrary cross section when irradiated by a plane wave of any polarization incident in a plane perpendicular to the generators. Application of the method to infinitely long hexagonal cylinders has yielded numerical scattering and absorption data which simulate columnar sheath ice crystals. It is found that the numerical procedures are economical for cylinders having perimeters less than approximately fifteen free-space wavelengths.

A maximally informative version of inelastic scattering of electromagnetic waves by Langmuir waves

NASA Astrophysics Data System (ADS)

Erofeev, V. I.

2015-09-01

The concept of informativeness of nonlinear plasma physics scenarios is explained. Natural ideas of developing highly informative models of plasma kinetics are spelled out. A maximally informative version of inelastic scattering of electromagnetic waves by Langmuir waves in a weakly turbulent inhomogeneous plasma is developed with consideration of possible changes in wave polarization. In addition, a new formula for wave drift in spatial positions and wave vectors is derived. New scenarios of the respective wave drift and inelastic scattering are compared with the previous visions. The results indicate the need for further revision of the traditional understanding of nonlinear plasma phenomena.

Research on the FDTD method of scattering effects of obliquely incident electromagnetic waves in time-varying plasma sheath on collision and plasma frequencies

NASA Astrophysics Data System (ADS)

Chen, Wei; Guo, Li-xin; Li, Jiang-ting

2017-04-01

This study analyzes the scattering characteristics of obliquely incident electromagnetic (EM) waves in a time-varying plasma sheath. The finite-difference time-domain algorithm is applied. According to the empirical formula of the collision frequency in a plasma sheath, the plasma frequency, temperature, and pressure are assumed to vary with time in the form of exponential rise. Some scattering problems of EM waves are discussed by calculating the radar cross section (RCS) of the time-varying plasma. The laws of the RCS varying with time are summarized at the L and S wave bands.

Modulated scattering technique in the terahertz domain enabled by current actuated vanadium dioxide switches

PubMed Central

Vitale, W. A.; Tamagnone, M.; Émond, N.; Le Drogoff, B.; Capdevila, S.; Skrivervik, A.; Chaker, M.; Mosig, J. R.; Ionescu, A. M.

2017-01-01

The modulated scattering technique is based on the use of reconfigurable electromagnetic scatterers, structures able to scatter and modulate an impinging electromagnetic field in function of a control signal. The modulated scattering technique is used in a wide range of frequencies up to millimeter waves for various applications, such as field mapping of circuits or antennas, radio-frequency identification devices and imaging applications. However, its implementation in the terahertz domain remains challenging. Here, we describe the design and experimental demonstration of the modulated scattering technique at terahertz frequencies. We characterize a modulated scatterer consisting in a bowtie antenna loaded with a vanadium dioxide switch, actuated using a continuous current. The modulated scatterer behavior is demonstrated using a time domain terahertz spectroscopy setup and shows significant signal strength well above 0.5 THz, which makes this device a promising candidate for the development of fast and energy-efficient THz communication devices and imaging systems. Moreover, our experiments allowed us to verify the operation of a single micro-meter sized VO2 switch at terahertz frequencies, thanks to the coupling provided by the antenna. PMID:28145523

Analysis of MUSIC-type imaging functional for single, thin electromagnetic inhomogeneity in limited-view inverse scattering problem

NASA Astrophysics Data System (ADS)

Ahn, Chi Young; Jeon, Kiwan; Park, Won-Kwang

2015-06-01

This study analyzes the well-known MUltiple SIgnal Classification (MUSIC) algorithm to identify unknown support of thin penetrable electromagnetic inhomogeneity from scattered field data collected within the so-called multi-static response matrix in limited-view inverse scattering problems. The mathematical theories of MUSIC are partially discovered, e.g., in the full-view problem, for an unknown target of dielectric contrast or a perfectly conducting crack with the Dirichlet boundary condition (Transverse Magnetic-TM polarization) and so on. Hence, we perform further research to analyze the MUSIC-type imaging functional and to certify some well-known but theoretically unexplained phenomena. For this purpose, we establish a relationship between the MUSIC imaging functional and an infinite series of Bessel functions of integer order of the first kind. This relationship is based on the rigorous asymptotic expansion formula in the existence of a thin inhomogeneity with a smooth supporting curve. Various results of numerical simulation are presented in order to support the identified structure of MUSIC. Although a priori information of the target is needed, we suggest a least condition of range of incident and observation directions to apply MUSIC in the limited-view problem.

Book Review: Book review

NASA Astrophysics Data System (ADS)

Mishchenko, Michael I.

2017-07-01

This fundamental (and in many respects encyclopedic) 755-page monograph was published as part of the "Mario Boella Series on Electromagnetism in Information and Communication" edited by P. L. E. Uslenghi. The main purpose of the book is systematic exposition of several important aspects of the electromagnetic scattering theory along with the presentation of the requisite mathematical apparatus and illustrative numerical results. What distinguishes this volume from the vast majority of related books is the extensive treatment of the time-domain scattering theory.

Scattering of electromagnetic wave by the layer with one-dimensional random inhomogeneities

NASA Astrophysics Data System (ADS)

Kogan, Lev; Zaboronkova, Tatiana; Grigoriev, Gennadii., IV.

A great deal of attention has been paid to the study of probability characteristics of electro-magnetic waves scattered by one-dimensional fluctuations of medium dielectric permittivity. However, the problem of a determination of a density of a probability and average intensity of the field inside the stochastically inhomogeneous medium with arbitrary extension of fluc-tuations has not been considered yet. It is the purpose of the present report to find and to analyze the indicated functions for the plane electromagnetic wave scattered by the layer with one-dimensional fluctuations of permittivity. We assumed that the length and the amplitude of individual fluctuations as well the interval between them are random quantities. All of indi-cated fluctuation parameters are supposed as independent random values possessing Gaussian distribution. We considered the stationary time cases both small-scale and large-scale rarefied inhomogeneities. Mathematically such problem can be reduced to the solution of integral Fred-holm equation of second kind for Hertz potential (U). Using the decomposition of the field into the series of multiply scattered waves we obtained the expression for a probability density of the field of the plane wave and determined the moments of the scattered field. We have shown that all odd moments of the centered field (U-¡U¿) are equal to zero and the even moments depend on the intensity. It was obtained that the probability density of the field possesses the Gaussian distribution. The average field is small compared with the standard fluctuation of scattered field for all considered cases of inhomogeneities. The value of average intensity of the field is an order of a standard of fluctuations of field intensity and drops with increases the inhomogeneities length in the case of small-scale inhomogeneities. The behavior of average intensity is more complicated in the case of large-scale medium inhomogeneities. The value of average intensity is the oscillating function versus the average fluctuations length if the standard of fluctuations of inhomogeneities length is greater then the wave length. When the standard of fluctuations of medium inhomogeneities extension is smaller then the wave length, the av-erage intensity value weakly depends from the average fluctuations extension. The obtained results may be used for analysis of the electromagnetic wave propagation into the media with the fluctuating parameters caused by such factors as leafs of trees, cumulus, internal gravity waves with a chaotic phase and etc. Acknowledgment: This work was supported by the Russian Foundation for Basic Research (projects 08-02-97026 and 09-05-00450).

On the determination of the electromagnetic field upon scattering by a small inhomogeneous spherical object

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shalashov, A. G., E-mail: ags@appl.sci-nnov.ru; Gospodchikov, E. D.

An efficient and fairly simple method of solving the problem of the incidence of a plane electromagnetic wave on an inhomogeneous object with specified spherically symmetric distributions of its electric permittivity and magnetic permeability is presented. The fields inside the object and the integrated scattering and absorption cross sections are found by assuming the object to be small compared to the vacuum wavelength. Since no constraints are imposed on the scales of the fields inside the object, the method is suitable for investigating complex cases, including those associated with the local amplification and absorption of the electromagnetic field in inhomogeneousmore » resonant media.« less

Condition for invariant spectrum of an electromagnetic wave scattered from an anisotropic random media.

PubMed

Li, Jia; Wu, Pinghui; Chang, Liping

2015-08-24

Within the accuracy of the first-order Born approximation, sufficient conditions are derived for the invariance of spectrum of an electromagnetic wave, which is generated by the scattering of an electromagnetic plane wave from an anisotropic random media. We show that the following restrictions on properties of incident fields and the anisotropic media must be simultaneously satisfied: 1) the elements of the dielectric susceptibility matrix of the media must obey the scaling law; 2) the spectral components of the incident field are proportional to each other; 3) the second moments of the elements of the dielectric susceptibility matrix of the media are inversely proportional to the frequency.

Nonlinear optical response in narrow graphene nanoribbons

NASA Astrophysics Data System (ADS)

Karimi, Farhad; Knezevic, Irena

We present an iterative method to calculate the nonlinear optical response of armchair graphene nanoribbons (aGNRs) and zigzag graphene nanoribbons (zGNRs) while including the effects of dissipation. In contrast to methods that calculate the nonlinear response in the ballistic (dissipation-free) regime, here we obtain the nonlinear response of an electronic system to an external electromagnetic field while interacting with a dissipative environment (to second order). We use a self-consistent-field approach within a Markovian master-equation formalism (SCF-MMEF) coupled with full-wave electromagnetic equations, and we solve the master equation iteratively to obtain the higher-order response functions. We employ the SCF-MMEF to calculate the nonlinear conductance and susceptibility, as well as to calculate the dependence of the plasmon dispersion and plasmon propagation length on the intensity of the electromagnetic field in GNRs. The electron scattering mechanisms included in this work are scattering with intrinsic phonons, ionized impurities, surface optical phonons, and line-edge roughness. Unlike in wide GNRs, where ionized-impurity scattering dominates dissipation, in ultra-narrow nanoribbons on polar substrates optical-phonon scattering and ionized-impurity scattering are equally prominent. Support by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-SC0008712.

Robust multiscale field-only formulation of electromagnetic scattering

NASA Astrophysics Data System (ADS)

Sun, Qiang; Klaseboer, Evert; Chan, Derek Y. C.

2017-01-01

We present a boundary integral formulation of electromagnetic scattering by homogeneous bodies that are characterized by linear constitutive equations in the frequency domain. By working with the Cartesian components of the electric E and magnetic H fields and with the scalar functions (r .E ) and (r .H ) where r is a position vector, the problem can be cast as having to solve a set of scalar Helmholtz equations for the field components that are coupled by the usual electromagnetic boundary conditions at material boundaries. This facilitates a direct solution for the surface values of E and H rather than having to work with surface currents or surface charge densities as intermediate quantities in existing methods. Consequently, our formulation is free of the well-known numerical instability that occurs in the zero-frequency or long-wavelength limit in traditional surface integral solutions of Maxwell's equations and our numerical results converge uniformly to the static results in the long-wavelength limit. Furthermore, we use a formulation of the scalar Helmholtz equation that is expressed as classically convergent integrals and does not require the evaluation of principal value integrals or any knowledge of the solid angle. Therefore, standard quadrature and higher order surface elements can readily be used to improve numerical precision for the same number of degrees of freedom. In addition, near and far field values can be calculated with equal precision, and multiscale problems in which the scatterers possess characteristic length scales that are both large and small relative to the wavelength can be easily accommodated. From this we obtain results for the scattering and transmission of electromagnetic waves at dielectric boundaries that are valid for any ratio of the local surface curvature to the wave number. This is a generalization of the familiar Fresnel formula and Snell's law, valid at planar dielectric boundaries, for the scattering and transmission of electromagnetic waves at surfaces of arbitrary curvature. Implementation details are illustrated with scattering by multiple perfect electric conductors as well as dielectric bodies with complex geometries and composition.

Introduction to Radar Polarimetry

DTIC Science & Technology

1991-04-23

Coulomb force 11 1,2 Static etectric fields 13 1.3 Summary 15 2 ELECTROMAGNETIC WAVES 16 2.1 Harmonic plane waves 16 2.2 The average intensity of a...harmonic plane wave 17 2.3 Spherical harmonic waves 18 2.4 Summary 19 3 THE POLARIZATION OF AN ELECTROMAGNETIC WAVE 20 3.1 The polarization ellipse 20 3.2...CHANGE OF POLARIZATION 31 4.1 Simple examples 31 4.2 Scattering at a plane interface 33 4.3 Summary 36 5 THE SCATTERING MATRIX 37 5.1 Transmission

Invisibility problem in acoustics, electromagnetism and heat transfer. Inverse design method

NASA Astrophysics Data System (ADS)

Alekseev, G.; Tokhtina, A.; Soboleva, O.

2017-10-01

Two approaches (direct design and inverse design methods) for solving problems of designing devices providing invisibility of material bodies of detection using different physical fields - electromagnetic, acoustic and static are discussed. The second method is applied for solving problems of designing cloaking devices for the 3D stationary thermal scattering model. Based on this method the design problems under study are reduced to respective control problems. The material parameters (radial and tangential heat conductivities) of the inhomogeneous anisotropic medium filling the thermal cloak and the density of auxiliary heat sources play the role of controls. A unique solvability of direct thermal scattering problem in the Sobolev space is proved and the new estimates of solutions are established. Using these results, the solvability of control problem is proved and the optimality system is derived. Based on analysis of optimality system, the stability estimates of optimal solutions are established and numerical algorithms for solving particular thermal cloaking problem are proposed.

Monte Carlo calculation of large and small-angle electron scattering in air

NASA Astrophysics Data System (ADS)

Cohen, B. I.; Higginson, D. P.; Eng, C. D.; Farmer, W. A.; Friedman, A.; Grote, D. P.; Larson, D. J.

2017-11-01

A Monte Carlo method for angle scattering of electrons in air that accommodates the small-angle multiple scattering and larger-angle single scattering limits is introduced. The algorithm is designed for use in a particle-in-cell simulation of electron transport and electromagnetic wave effects in air. The method is illustrated in example calculations.

Permittivity estimation over Mars by using SHARAD data: the Cerberus Palus area

NASA Astrophysics Data System (ADS)

Alberti, Giovanni; Castaldo, Luigi; Orosei, Roberto; Frigeri, Alessandro; Cirillo, Giuseppe

2012-09-01

Cerberus Palus is a thoroughly studied region of Mars, characterized by evident platy textures that were interpreted either as evidence for a frozen sea close to Mars' equator or as being resultant of lava, mud or ice-flows coming from Cerberus Fossae through Athabasca Valles. Radargrams provided by radar sounder SHARAD clearly show the presence of subsurface layers in the area. By exploiting the great amount of available data, authors have performed an accurate quantitative analysis aimed to estimate electromagnetic properties of surface and subsurface layers, in terms of permittivity and attenuation. To this aim, a simplified electromagnetic approach has been used, but taking into account effects of scattering due to surface roughness, for avoiding overestimated results. This has been done by using theory of electromagnetic scattering from fractal surfaces and by estimating needed parameters from topographic data provided by MOLA. Three distinct geologic formations have been analyzed, namely a part of Zephyria Planum, the Cerberus plains and the bedrock beneath the plains. The retrieved electromagnetic parameters have been also modeled as a mixture of volcanic rocks with either ice or air. The Zephyria Planum material was found to be significantly porous [50-60%] with an attenuation more likely compatible with empty pores. Ambiguous results were obtained for the plains material, being the resulting porosity high in both the cases of empty [40-50%] and of ice-filled [80%] pores. The obtained results do not allow for evidence of a frozen sea on Cerberus Palus area.

Electromagnetic structure of the proton within the CP-violation hypothesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krutov, A. F., E-mail: krutov@ssu.samara.ru; Kudinov, M. Yu., E-mail: kudinov@ssu.samara.ru

2013-11-15

The so-called non-Rosenbluth behavior of the proton electromagnetic form factors can be explained within the hypothesis of CP violation in electromagnetic processes involving composite systems of strongly interacting particles. It is shown that this hypothesis leads to the appearance of an additional, anapole, form factor of the proton. The proton electromagnetic form factors, including the anapole form factor, are estimated on the basis of experimental data on elastic electron-proton scattering.

The EMCC / DARPA Massively Parallel Electromagnetic Scattering Project

NASA Technical Reports Server (NTRS)

Woo, Alex C.; Hill, Kueichien C.

1996-01-01

The Electromagnetic Code Consortium (EMCC) was sponsored by the Advanced Research Program Agency (ARPA) to demonstrate the effectiveness of massively parallel computing in large scale radar signature predictions. The EMCC/ARPA project consisted of three parts.

A laboratory study of the electromagnetic bias of rough surface scattering by water waves

NASA Technical Reports Server (NTRS)

Parsons, Chester L.; Miller, Lee S.

1990-01-01

The design, development, and use of a focused-beam radar to measure the electromagnetic bias introduced by the scattering of radar waves by a roughened water surface are discussed. The bias measurements were made over wide ranges of environmental conditions in a wavetank laboratory. Wave-elevation data were provided by standard laboratory capacitance probes. Backscattered radar power measurements coincident in time and space with the elevation data were produced by the radar. The two data sets are histogrammed to produce probability density functions for elevation and radar reflectivity, from which the electromagnetic bias is computed. The experimental results demonstrate that the electromagnetic bias is quite variable over the wide range of environmental conditions that can be produced in the laboratory. The data suggest that the bias is dependent upon the local wind field and on the amplitude and frequency of any background wave field that is present.

A Numerical Analysis of Electromagnetic Scattering from Two-Dimensional Edge Terminations

NASA Technical Reports Server (NTRS)

Gray, B. E.; Dominek, A. K.; Wang, N.

1995-01-01

Several techniques that influence the low frequency scattering from penetrable edge terminations are evaluated using a hybrid finite element and boundary element method code. The edge terminations consist of a dielectric skin forming an exterior shape with an internal conducting bulkhead. Some of the techniques considered are bulkhead shaping, internal material loading, placement of resistive cards, and the placement of lossy dielectric material rods. The intent of the various treatments is to find a combination or combinations that influence(s) the backscattered field to acceptable levels over a range of frequencies for both transverse magnetic and transverse electric polarizations.

Comparisons of neutrino event generators from an oscillation-experiment perspective

NASA Astrophysics Data System (ADS)

Mayer, Nathan

2015-05-01

Monte Carlo generators are crucial to the analysis of high energy physics data, ideally giving a baseline comparison between the state-of-art theoretical models and experimental data. Presented here is a comparison between three of final state distributions from the GENIE, Neut, NUANCE, and NuWro neutrino Monte Carlo event generators. The final state distributions chosen for comparison are: the electromagnetic energy fraction in neutral current interactions, the energy of the leading π0 vs. the scattering angle for neutral current interactions, and the muon energy vs. scattering angle of νµ charged current interactions.

Analysis of {sup 4}He+{sup 40}Ca and {sup 4}He+{sup 44}Ti scattering using different optical model potentials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ibraheem, Awad A., E-mail: awad-ah-eb@hotmail.com

Elastic scattering of {sup 4}He+{sup 40}Ca and {sup 4}He+{sup 44}Ti reactions at backward angles has been analyzed using two different models, microscopic and semimicroscopic folding potentials. The derived real potentials supplemented with phenomenological Woods–Saxon imaginary potentials, provide good agreement with the experimental data at energy E{sub c.m.} = 21.8 MeV without need to renormalize the potentials. Coupled channels calculations are used to extract the inelastic scattering cross section to the low-lying state 2+ (1.083 MeV) of {sup 44}Ti. The deformation length is obtained and compared with the electromagnetic measurement values as well as those obtained from previous studies.

Geometric saliency to characterize radar exploitation performance

NASA Astrophysics Data System (ADS)

Nolan, Adam; Keserich, Brad; Lingg, Andrew; Goley, Steve

2014-06-01

Based on the fundamental scattering mechanisms of facetized computer-aided design (CAD) models, we are able to define expected contributions (EC) to the radar signature. The net result of this analysis is the prediction of the salient aspects and contributing vehicle morphology based on the aspect. Although this approach does not provide the fidelity of an asymptotic electromagnetic (EM) simulation, it does provide very fast estimates of the unique scattering that can be consumed by a signature exploitation algorithm. The speed of this approach is particularly relevant when considering the high dimensionality of target configuration variability due to articulating parts which are computationally burdensome to predict. The key scattering phenomena considered in this work are the specular response from a single bounce interaction with surfaces and dihedral response formed between the ground plane and vehicle. Results of this analysis are demonstrated for a set of civilian target models.

The application of contraction theory to an iterative formulation of electromagnetic scattering

NASA Technical Reports Server (NTRS)

Brand, J. C.; Kauffman, J. F.

1985-01-01

Contraction theory is applied to an iterative formulation of electromagnetic scattering from periodic structures and a computational method for insuring convergence is developed. A short history of spectral (or k-space) formulation is presented with an emphasis on application to periodic surfaces. To insure a convergent solution of the iterative equation, a process called the contraction corrector method is developed. Convergence properties of previously presented iterative solutions to one-dimensional problems are examined utilizing contraction theory and the general conditions for achieving a convergent solution are explored. The contraction corrector method is then applied to several scattering problems including an infinite grating of thin wires with the solution data compared to previous works.

Scattering theory derivation of a 3D acoustic cloaking shell.

PubMed

Cummer, Steven A; Popa, Bogdan-Ioan; Schurig, David; Smith, David R; Pendry, John; Rahm, Marco; Starr, Anthony

2008-01-18

Through acoustic scattering theory we derive the mass density and bulk modulus of a spherical shell that can eliminate scattering from an arbitrary object in the interior of the shell--in other words, a 3D acoustic cloaking shell. Calculations confirm that the pressure and velocity fields are smoothly bent and excluded from the central region as for previously reported electromagnetic cloaking shells. The shell requires an anisotropic mass density with principal axes in the spherical coordinate directions and a radially dependent bulk modulus. The existence of this 3D cloaking shell indicates that such reflectionless solutions may also exist for other wave systems that are not isomorphic with electromagnetics.

Generation of Optical Vortices by Nonlinear Inverse Thomson Scattering at Arbitrary Angle Interactions

NASA Astrophysics Data System (ADS)

Taira, Yoshitaka; Katoh, Masahiro

2018-06-01

We theoretically verify that optical vortices carrying orbital angular momentum are generated in various astrophysical situations via nonlinear inverse Thomson scattering. Arbitrary angle collisions between relativistic electrons and circularly polarized strong electromagnetic waves are treated. We reveal that the higher harmonic components of scattered photons carry well-defined orbital angular momentum under a specific condition that the Lorentz factor of the electron is much larger than the field strength parameter of the electromagnetic wave. Our study indicates that optical vortices in a wide frequency range from radio waves to gamma-rays are naturally generated in environments where high-energy electrons interact with circularly polarized strong electromagnetic waves at various interaction angles. Optical vortices should be a new multi-messenger member carrying information concerning the physical circumstances of their sources, e.g., the magnetic and radiation fields. Moreover, their interactions with matter via their orbital angular momenta may play an important role in the evolution of matter in the universe.

Effect of void shape in Czochralski-Si wafers on the intensity of laser-scattering

NASA Astrophysics Data System (ADS)

Takahashi, J.; Kawakami, K.; Nakai, K.

2001-06-01

The shape effect of anisotropic-shaped microvoid defects in Czochralski-grown silicon wafers on the intensity of laser scattering has been investigated. The size and shape of the defects were examined by means of transmission electron microscopy. Octahedral voids in conventional (nitrogen-undoped) wafers showed an almost isotropic scattering property under the incident condition of a p-polarization beam. On the other hand, parallelepiped-plate-shaped voids in nitrogen-doped wafers showed an anisotropic scattering property on both p- and s-polarized components of scattered light, depending strongly on the incident laser direction. The measured results were explained not by scattering calculation using Born approximation but by calculation based on Rayleigh scattering. It was found that the s component is explained by an inclination of a dipole moment induced on a defect from the scattering plane. Furthermore, using numerical electromagnetic analysis it was shown that the asymmetric behavior of the s component on the parallelepiped-plate voids is ascribed to the parallelepiped shape effect. These results suggest that correction of the scattering intensity is necessary to evaluate the size and volume of anisotropic-shaped defects from the scattered intensity.

Simulation electromagnetic scattering on bodies through integral equation and neural networks methods

NASA Astrophysics Data System (ADS)

Lvovich, I. Ya; Preobrazhenskiy, A. P.; Choporov, O. N.

2018-05-01

The paper deals with the issue of electromagnetic scattering on a perfectly conducting diffractive body of a complex shape. Performance calculation of the body scattering is carried out through the integral equation method. Fredholm equation of the second time was used for calculating electric current density. While solving the integral equation through the moments method, the authors have properly described the core singularity. The authors determined piecewise constant functions as basic functions. The chosen equation was solved through the moments method. Within the Kirchhoff integral approach it is possible to define the scattered electromagnetic field, in some way related to obtained electrical currents. The observation angles sector belongs to the area of the front hemisphere of the diffractive body. To improve characteristics of the diffractive body, the authors used a neural network. All the neurons contained a logsigmoid activation function and weighted sums as discriminant functions. The paper presents the matrix of weighting factors of the connectionist model, as well as the results of the optimized dimensions of the diffractive body. The paper also presents some basic steps in calculation technique of the diffractive bodies, based on the combination of integral equation and neural networks methods.

Comparison of Cartesian grid configurations for application of the finite-difference time-domain method to electromagnetic scattering by dielectric particles.

PubMed

Yang, Ping; Kattawar, George W; Liou, Kuo-Nan; Lu, Jun Q

2004-08-10

Two grid configurations can be employed to implement the finite-difference time-domain (FDTD) technique in a Cartesian system. One configuration defines the electric and magnetic field components at the cell edges and cell-face centers, respectively, whereas the other reverses these definitions. These two grid configurations differ in terms of implication on the electromagnetic boundary conditions if the scatterer in the FDTD computation is a dielectric particle. The permittivity has an abrupt transition at the cell interface if the dielectric properties of two adjacent cells are not identical. Similarly, the discontinuity of permittivity is also observed at the edges of neighboring cells that are different in terms of their dielectric constants. We present two FDTD schemes for light scattering by dielectric particles to overcome the above-mentioned discontinuity on the basis of the electromagnetic boundary conditions for the two Cartesian grid configurations. We also present an empirical approach to accelerate the convergence of the discrete Fourier transform to obtain the field values in the frequency domain. As a new application of the FDTD method, we investigate the scattering properties of multibranched bullet-rosette ice crystals at both visible and thermal infrared wavelengths.

Systems and methods for locating and imaging proppant in an induced fracture

DOEpatents

Aldridge, David F.; Bartel, Lewis C.

2016-02-02

Born Scattering Inversion (BSI) systems and methods are disclosed. A BSI system may be incorporated in a well system for accessing natural gas, oil and geothermal reserves in a geologic formation beneath the surface of the Earth. The BSI system may be used to generate a three-dimensional image of a proppant-filled hydraulically-induced fracture in the geologic formation. The BSI system may include computing equipment and sensors for measuring electromagnetic fields in the vicinity of the fracture before and after the fracture is generated, adjusting the parameters of a first Born approximation model of a scattered component of the surface electromagnetic fields using the measured electromagnetic fields, and generating the image of the proppant-filled fracture using the adjusted parameters.

Scattering properties of electromagnetic waves from metal object in the lower terahertz region

NASA Astrophysics Data System (ADS)

Chen, Gang; Dang, H. X.; Hu, T. Y.; Su, Xiang; Lv, R. C.; Li, Hao; Tan, X. M.; Cui, T. J.

2018-01-01

An efficient hybrid algorithm is proposed to analyze the electromagnetic scattering properties of metal objects in the lower terahertz (THz) frequency. The metal object can be viewed as perfectly electrical conducting object with a slightly rough surface in the lower THz region. Hence the THz scattered field from metal object can be divided into coherent and incoherent parts. The physical optics and truncated-wedge incremental-length diffraction coefficients methods are combined to compute the coherent part; while the small perturbation method is used for the incoherent part. With the MonteCarlo method, the radar cross section of the rough metal surface is computed by the multilevel fast multipole algorithm and the proposed hybrid algorithm, respectively. The numerical results show that the proposed algorithm has good accuracy to simulate the scattering properties rapidly in the lower THz region.

Application of Dynamic Logic Algorithm to Inverse Scattering Problems Related to Plasma Diagnostics

NASA Astrophysics Data System (ADS)

Perlovsky, L.; Deming, R. W.; Sotnikov, V.

2010-11-01

In plasma diagnostics scattering of electromagnetic waves is widely used for identification of density and wave field perturbations. In the present work we use a powerful mathematical approach, dynamic logic (DL), to identify the spectra of scattered electromagnetic (EM) waves produced by the interaction of the incident EM wave with a Langmuir soliton in the presence of noise. The problem is especially difficult since the spectral amplitudes of the noise pattern are comparable with the amplitudes of the scattered waves. In the past DL has been applied to a number of complex problems in artificial intelligence, pattern recognition, and signal processing, resulting in revolutionary improvements. Here we demonstrate its application to plasma diagnostic problems. [4pt] Perlovsky, L.I., 2001. Neural Networks and Intellect: using model-based concepts. Oxford University Press, New York, NY.

A high frequency analysis of electromagnetic plane wave scattering by perfectly-conducting semi-infinite parallel plate and rectangular waveguides with absorber coated inner walls

NASA Technical Reports Server (NTRS)

Noh, H. M.; Pathak, P. H.

1986-01-01

An approximate but sufficiently accurate high frequency solution which combines the uniform geometrical theory of diffraction (UTD) and the aperture integration (AI) method is developed for analyzing the problem of electromagnetic (EM) plane wave scattering by an open-ended, perfectly-conducting, semi-infinite hollow rectangular waveguide (or duct) with a thin, uniform layer of lossy or absorbing material on its inner wall, and with a planar termination inside. In addition, a high frequency solution for the EM scattering by a two dimensional (2-D), semi-infinite parallel plate waveguide with a absorber coating on the inner walls is also developed as a first step before analyzing the open-ended semi-infinite three dimensional (3-D) rectangular waveguide geometry. The total field scattered by the semi-infinite waveguide consists firstly of the fields scattered from the edges of the aperture at the open-end, and secondly of the fields which are coupled into the waveguide from the open-end and then reflected back from the interior termination to radiate out of the open-end. The first contribution to the scattered field can be found directly via the UTD ray method. The second contribution is found via the AI method which employs rays to describe the fields in the aperture that arrive there after reflecting from the interior termination. It is assumed that the direction of the incident plane wave and the direction of observation lie well inside the forward half space tht exists outside the half space containing the semi-infinite waveguide geometry. Also, the medium exterior to the waveguide is assumed to be free space.

A new technique for the characterization of chaff elements

NASA Astrophysics Data System (ADS)

Scholfield, David; Myat, Maung; Dauby, Jason; Fesler, Jonathon; Bright, Jonathan

2011-07-01

A new technique for the experimental characterization of electromagnetic chaff based on Inverse Synthetic Aperture Radar is presented. This technique allows for the characterization of as few as one filament of chaff in a controlled anechoic environment allowing for stability and repeatability of experimental results. This approach allows for a deeper understanding of the fundamental phenomena of electromagnetic scattering from chaff through an incremental analysis approach. Chaff analysis can now begin with a single element and progress through the build-up of particles into pseudo-cloud structures. This controlled incremental approach is supported by an identical incremental modeling and validation process. Additionally, this technique has the potential to produce considerable savings in financial and schedule cost and provides a stable and repeatable experiment to aid model valuation.

Sparsity Aware Adaptive Radar Sensor Imaging in Complex Scattering Environments

DTIC Science & Technology

2015-06-15

while meeting the requirement on the peak to average power ratio. Third, we study impact of waveform encoding on nonlinear electromagnetic tomographic...Enyue Lu. Time Domain Electromagnetic Tomography Using Propagation and Backpropagation Method, IEEE International Conference on Image Processing...Received Paper 3.00 4.00 Yuanwei Jin, Chengdon Dong, Enyue Lu. Waveform Encoding for Nonlinear Electromagnetic Tomographic Imaging, IEEE Global

Monte Carlo calculation of large and small-angle electron scattering in air

DOE PAGES

Cohen, B. I.; Higginson, D. P.; Eng, C. D.; ...

2017-08-12

A Monte Carlo method for angle scattering of electrons in air that accommodates the small-angle multiple scattering and larger-angle single scattering limits is introduced. In this work, the algorithm is designed for use in a particle-in-cell simulation of electron transport and electromagnetic wave effects in air. The method is illustrated in example calculations.

Analysis on the electromagnetic scattering properties of crops at multi-band

NASA Astrophysics Data System (ADS)

Wu, Tao; Wu, Zhensen; Liu, Xiaoyi

2014-12-01

The vector radiative transfer (VRT) theory for active microwave remote sensing and Rayleigh-Gans approximation (GRG) are applied in the study, and an iterative algorithm is used to solve the RT equations, thus we obtain the zeroorder and first-order equation for numerical results. The Michigan Microwave Canopy Scattering (MIMICS) model is simplified to adapt to the crop model, by analyzing body-surface bistatic scattering and backscattering properties between a layer of soybean or wheat consisting of stems and leaves and different underlying soil surface at multi-band (i.e. P, L, S, X, Ku-band), we obtain microwave scattering mechanisms of crop components and the effect of underlying ground on total crop scattering. Stem and leaf are regard as a needle and a circular disk, respectively. The final results are compared with some literature data to verify our calculating method, numerical results show multi-band crop microwave scattering properties differ from scattering angle, azimuth angle and moisture of vegetation and soil, which offer the part needed information for the design of future bistatic radar systems for crop sensing applications.

Size validity of plasma-metamaterial cloaking monitored by scattering wave in finite-difference time-domain method

NASA Astrophysics Data System (ADS)

Bambina, Alexandre; Yamaguchi, Shuhei; Iwai, Akinori; Miyagi, Shigeyuki; Sakai, Osamu

2018-01-01

Limitation of the cloak-size reduction is investigated numerically by a finite-difference time-domain (FDTD) method. A metallic pole that imitates an antenna is cloaked with an anisotropic and parameter-gradient medium against electromagnetic-wave propagation in microwave range. The cloaking structure is a metamaterial submerged in a plasma confined in a vacuum chamber made of glass. The smooth-permittivity plasma can be compressed in the radial direction, which enables us to decrease the size of the cloak. Theoretical analysis is performed numerically by comparing scattering waves in various cases; there exists a high reduction of the scattering wave when the radius of the cloak is larger than a quarter of one wavelength. This result indicates that the required size of the cloaking layer is more than an object scale in the Rayleigh scattering regime.

Time-reversal MUSIC imaging of extended targets.

PubMed

Marengo, Edwin A; Gruber, Fred K; Simonetti, Francesco

2007-08-01

This paper develops, within a general framework that is applicable to rather arbitrary electromagnetic and acoustic remote sensing systems, a theory of time-reversal "MUltiple Signal Classification" (MUSIC)-based imaging of extended (nonpoint-like) scatterers (targets). The general analysis applies to arbitrary remote sensing geometry and sheds light onto how the singular system of the scattering matrix relates to the geometrical and propagation characteristics of the entire transmitter-target-receiver system and how to use this effect for imaging. All the developments are derived within exact scattering theory which includes multiple scattering effects. The derived time-reversal MUSIC methods include both interior sampling, as well as exterior sampling (or enclosure) approaches. For presentation simplicity, particular attention is given to the time-harmonic case where the informational wave modes employed for target interrogation are purely spatial, but the corresponding generalization to broadband fields is also given. This paper includes computer simulations illustrating the derived theory and algorithms.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mackowski, Daniel W.; Mishchenko, Michael I.

The conventional orientation-averaging procedure developed in the framework of the superposition T-matrix approach is generalized to include the case of illumination by a Gaussian beam (GB). The resulting computer code is parallelized and used to perform extensive numerically exact calculations of electromagnetic scattering by volumes of discrete random medium consisting of monodisperse spherical particles. The size parameters of the scattering volumes are 40, 50, and 60, while their packing density is fixed at 5%. We demonstrate that all scattering patterns observed in the far-field zone of a random multisphere target and their evolution with decreasing width of the incident GBmore » can be interpreted in terms of idealized theoretical concepts such as forward-scattering interference, coherent backscattering (CB), and diffuse multiple scattering. It is shown that the increasing violation of electromagnetic reciprocity with decreasing GB width suppresses and eventually eradicates all observable manifestations of CB. This result supplements the previous demonstration of the effects of broken reciprocity in the case of magneto-optically active particles subjected to an external magnetic field.« less

Theory of scattering of electromagnetic waves of the microwave range in a turbid medium

NASA Astrophysics Data System (ADS)

Konstantinov, O. V.; Matveentsev, A. V.

2013-02-01

The coefficient of extinction of electromagnetic waves of the microwave range due to their scattering from clusters suspended in an amorphous medium and responsible for turbidity is calculated. Turbidity resembles the case when butter clusters transform water into milk. In the case under investigation, the clusters are conductors (metallic or semiconducting). The extinction coefficient is connected in a familiar way with the cross section of light scattering from an individual cluster. A new formula is derived for the light scattering cross section in the case when damping of oscillations of an electron is due only to spontaneous emission of light quanta. In this case, the resonant scattering cross section for light can be very large. It is shown that this can be observed only in a whisker nanocluster. In addition, the phonon energy on a whisker segment must be higher than the photon energy, which is close to the spacing between the electron energy levels in the cluster.

ELECTROMAGNETIC SCATTERING AND ANTENNA TECHNOLOGY (EMSAT) Task Order 0003: Design of a Circularly Polarized, 20 60 GHZ Active Phased Array for Wide Angle Scanning

DTIC Science & Technology

2017-08-08

Another area of the design that needs to be experimentally tested is the SMPS connectors used to attach the two beamforming stages together. In...AFRL-RY-WP-TR-2017-0104 ELECTROMAGNETIC SCATTERING AND ANTENNA TECHNOLOGY (EMSAT) Task Order 0003: Design of a Circularly Polarized, 20-60...Order 0003: Design of a Circularly Polarized, 20-60 GHZ Active Phased Array for Wide Angle Scanning 5a. CONTRACT NUMBER FA8650-14-D-1714-0003 5b

Efficient Solution of Three-Dimensional Problems of Acoustic and Electromagnetic Scattering by Open Surfaces

NASA Technical Reports Server (NTRS)

Turc, Catalin; Anand, Akash; Bruno, Oscar; Chaubell, Julian

2011-01-01

We present a computational methodology (a novel Nystrom approach based on use of a non-overlapping patch technique and Chebyshev discretizations) for efficient solution of problems of acoustic and electromagnetic scattering by open surfaces. Our integral equation formulations (1) Incorporate, as ansatz, the singular nature of open-surface integral-equation solutions, and (2) For the Electric Field Integral Equation (EFIE), use analytical regularizes that effectively reduce the number of iterations required by iterative linear-algebra solution based on Krylov-subspace iterative solvers.

The Dubna-Mainz-Taipei Dynamical Model for πN Scattering and π Electromagnetic Production

NASA Astrophysics Data System (ADS)

Yang, Shin Nan

Some of the featured results of the Dubna-Mainz-Taipei (DMT) dynamical model for πN scattering and π0 electromagnetic production are summarized. These include results for threshold π0 production, deformation of Δ(1232),and the extracted properties of higher resonances below 2 GeV. The excellent agreement of DMT model's predictions with threshold π0 production data, including the recent precision measurements from MAMI establishes results of DMT model as a benchmark for experimentalists and theorists in dealing with threshold pion production.

Absorption of electromagnetic radiation in a quantum wire with an anisotropic parabolic potential in a transverse magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karpunin, V. V., E-mail: karpuninvv@mail.ru; Margulis, V. A., E-mail: theorphysics@mrsu.ru

2016-06-15

An analytical expression for the coefficient of absorption of electromagnetic radiation by electrons in a quantum wire in a magnetic field is derived. The case of a magnetic field transverse with respect to the wire axis is considered. The resonance character of absorption is shown, and the resonance frequencies as functions of the field are determined. The effect of the scattering of electrons at optical phonons is studied, and it is shown that scattering is responsible for additional resonance absorption peaks.

Spontaneous periodic ordering on the surface and in the bulk of dielectrics irradiated by ultrafast laser: a shared electromagnetic origin.

PubMed

Rudenko, Anton; Colombier, Jean-Philippe; Höhm, Sandra; Rosenfeld, Arkadi; Krüger, Jörg; Bonse, Jörn; Itina, Tatiana E

2017-09-26

Periodic self-organization of matter beyond the diffraction limit is a puzzling phenomenon, typical both for surface and bulk ultrashort laser processing. Here we compare the mechanisms of periodic nanostructure formation on the surface and in the bulk of fused silica. We show that volume nanogratings and surface nanoripples having subwavelength periodicity and oriented perpendicular to the laser polarization share the same electromagnetic origin. The nanostructure orientation is defined by the near-field local enhancement in the vicinity of the inhomogeneous scattering centers. The periodicity is attributed to the coherent superposition of the waves scattered at inhomogeneities. Numerical calculations also support the multipulse accumulation nature of nanogratings formation on the surface and inside fused silica. Laser surface processing by multiple laser pulses promotes the transition from the high spatial frequency perpendicularly oriented nanoripples to the low spatial frequency ripples, parallel or perpendicular to the laser polarization. The latter structures also share the electromagnetic origin, but are related to the incident field interference with the scattered far-field of rough non-metallic or transiently metallic surfaces. The characteristic ripple appearances are predicted by combined electromagnetic and thermo-mechanical approaches and supported by SEM images of the final surface morphology and by time-resolved pump-probe diffraction measurements.

Analysis of scattering by spheres having a negative acoustical refractive index

NASA Astrophysics Data System (ADS)

Marston, Philip L.

2005-04-01

Electromagnetic waves having oppositely directed phase and group velocities propagate in metamaterials having a negative permeability and negative permittivity [J. B. Pendry and D. R. Smith, Phys. Today 57(6), 37-44 (2004)]. Such materials are predicted to have unusual electromagnetic scattering properties [R. Ruppin, Solid State Commun. 116, 411-415 (2000)]. If it is possible to fabricate acoustical materials having a simultaneously negative effective elastic modulus and density (in a dynamical sense), the mechanical energy flux will have the opposite direction as the wave-vector associated with phase evolution. Rays descriptive of the energy flux refracted by such hypothetical materials at interfaces with ordinary fluids would be characterized by a negative acoustical refractive index. Partial-wave-series calculations of high frequency scattering by fluid spheres having an acoustical refractive index at (or close to) 1 reveal backscattering enhancements associated with glory rays which, unlike ordinary spheres [P. L. Marston and D. S. Langley, J. Acoust. Soc. Am. 73, 1464-1475 (1983)], require only a single internal chord. Generalized Lamb waves on elastic shells having opposite phase and group velocities also cause enhanced backscattering associated with unusual rays [G. Kaduchak, D. H. Hughes, and P. L. Marston, J. Acoust. Soc. Am. 96, 3704-3714 (1994)].

Applicability of Rayleigh–Gans Scattering to Spherical Particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kerker, M.; Farone, W. A.; Matijevic, E.

1963-01-01

Exact computations of scattering functions for spheres are compared with those obtained from the Rayleigh-Gans theory of scattering of electromagnetic radiation. The range of validity for spheres as a guide for non-homogeneous particles and other geometries. This study is limited to non-absorbing particles with real indices of refraction. (C.E.S.)

Direct Simulation of Multiple Scattering by Discrete Random Media Illuminated by Gaussian Beams

NASA Technical Reports Server (NTRS)

Mackowski, Daniel W.; Mishchenko, Michael I.

2011-01-01

The conventional orientation-averaging procedure developed in the framework of the superposition T-matrix approach is generalized to include the case of illumination by a Gaussian beam (GB). The resulting computer code is parallelized and used to perform extensive numerically exact calculations of electromagnetic scattering by volumes of discrete random medium consisting of monodisperse spherical particles. The size parameters of the scattering volumes are 40, 50, and 60, while their packing density is fixed at 5%. We demonstrate that all scattering patterns observed in the far-field zone of a random multisphere target and their evolution with decreasing width of the incident GB can be interpreted in terms of idealized theoretical concepts such as forward-scattering interference, coherent backscattering (CB), and diffuse multiple scattering. It is shown that the increasing violation of electromagnetic reciprocity with decreasing GB width suppresses and eventually eradicates all observable manifestations of CB. This result supplements the previous demonstration of the effects of broken reciprocity in the case of magneto-optically active particles subjected to an external magnetic field.

Phase function of a spherical particle when scattering an inhomogeneous electromagnetic plane wave.

PubMed

Frisvad, Jeppe Revall

2018-04-01

In absorbing media, electromagnetic plane waves are most often inhomogeneous. Existing solutions for the scattering of an inhomogeneous plane wave by a spherical particle provide no explicit expressions for the scattering components. In addition, current analytical solutions require evaluation of the complex hypergeometric function F 1 2 for every term of a series expansion. In this work, I develop a simpler solution based on associated Legendre functions with argument zero. It is similar to the solution for homogeneous plane waves but with new explicit expressions for the angular dependency of the far-field scattering components, that is, the phase function. I include recurrence formulas for practical evaluation and provide numerical examples to evaluate how well the new expressions match previous work in some limiting cases. The predicted difference in the scattering phase function due to inhomogeneity is not negligible for light entering an absorbing medium at an oblique angle. The presented theory could thus be useful for predicting scattering behavior in dye-based random lasing and in solar cell absorption enhancement.

Tunable multiband directional electromagnetic scattering from spoof Mie resonant structure.

PubMed

Wu, Hong-Wei; Chen, Hua-Jun; Xu, Hua-Feng; Fan, Ren-Hao; Li, Yang

2018-06-11

We demonstrate that directional electromagnetic scattering can be realized in an artificial Mie resonant structure that supports electric and magnetic dipole modes simultaneously. The directivity of the far-field radiation pattern can be switched by changing wavelength of the incident light as well as tailoring the geometric parameters of the structure. In addition, we further design a quasiperiodic spoof Mie resonant structure by alternately inserting two materials into the slits. The results show that multi-band directional light scattering is realized by exciting multiple electric and magnetic dipole modes with different frequencies in the quasiperiodic structure. The presented design concept is suitable for microwave to terahertz region and can be applied to various advanced optical devices, such as antenna, metamaterial and metasurface.

Advanced studies of electromagnetic scattering

NASA Technical Reports Server (NTRS)

Ling, Hao

1994-01-01

In radar signature applications it is often desirable to generate the range profiles and inverse synthetic aperture radar (ISAR) images of a target. They can be used either as identification tools to distinguish and classify the target from a collection of possible targets, or as diagnostic/design tools to pinpoint the key scattering centers on the target. The simulation of synthetic range profiles and ISAR images is usually a time intensive task and computation time is of prime importance. Our research has been focused on the development of fast simulation algorithms for range profiles and ISAR images using the shooting and bouncing ray (SBR) method, a high frequency electromagnetic simulation technique for predicting the radar returns from realistic aerospace vehicles and the scattering by complex media.

Biologically Inspired Radio-Frequency (RF) Direction Finding

DTIC Science & Technology

2015-12-15

estimation of an electromagnetic signal is important for many commercial and military applications including electronic warfare [1] and mobile...without scatter with scatter 1 Incident Angle (degree) 0 30 60 90 R ec ei ve d Pa tte rn (d B ) -62 -60 -58 -56 -54 -52 -50 port1 without scatter...150 without scatter with scatter 2 Incident Angle (degree) 0 30 60 90 R ec ei ve d Pa tte rn (d B ) -52 -50 -48 -46 -44 -42 port1 without scatter

Electromagnetic and Light Scattering by Nonspherical Particles XV: Celebrating 150 Years of Maxwell's Electromagnetics

NASA Technical Reports Server (NTRS)

Macke, Andreas; Mishchenko, Michael I.

2015-01-01

The 15th Electromagnetic and Light Scattering Conference (ELS-XV) was held in Leipzig, Germany from 21 to 26 of June 2015. This conference built on the great success of the previous meetings held in Amsterdam (1995), Helsinki(1997) [2], New York City(1998) [3], Vigo (1999),Halifax (2000), Gainesville (2002), Bremen (2003), Salobreña (2005), St. Petersburg (2006), Bodrum (2007), Hatfield (2008), Helsinki (2010), Taormina (2011), and Lille as well as the workshops held in Bremen (1996,1998) and Moscow (1997). As usual, the main objective of this conference was to bring together scientists, engineers, and PhD students studying various aspects of electromagnetic scattering and to provide a relaxed atmosphere for in-depth discussion of theory, measurements, and applications. Furthermore, ELS-XV supported the United Nations "Year of Light" and celebrated the150th anniversary of Maxwell's electromagnetics. Maxwell's paper on "A Dynamical Theory of the Electromagnetic Field" was published in1865 and has widely been acknowledged as one of the supreme achievements in the history of science. The conference was attended by136 scientists from 22 countries. The scientific program included two plenary lectures, 16 invited reviews, 88 contributed oral talks, and 70 poster presentations. The program and the abstracts of conference presentations are available at the conference website http://www.els-xv-2015.net/home.html. Following the well-established ELS practice and with Elsevier's encouragement, we solicited full-size papers for a topical issue of the Journal of Quantitative Spectroscopy and Radiative Transfer (JQSRT). The result of this collective effort is now in the reader's hands. As always, every invited review and regular paper included in this topical issue has undergone the same rigorous peer review process as any other manuscript published in the JQSRT.

Asymptotic symmetries and electromagnetic memory

NASA Astrophysics Data System (ADS)

Pasterski, Sabrina

2017-09-01

Recent investigations into asymptotic symmetries of gauge theory and gravity have illuminated connections between gauge field zero-mode sectors, the corresponding soft factors, and their classically observable counterparts — so called "memories". Namely, low frequency emissions in momentum space correspond to long time integrations of the corre-sponding radiation in position space. Memory effect observables constructed in this manner are non-vanishing in typical scattering processes, which has implications for the asymptotic symmetry group. Here we complete this triad for the case of large U(1) gauge symmetries at null infinity. In particular, we show that the previously studied electromagnetic memory effect, whereby the passage of electromagnetic radiation produces a net velocity kick for test charges in a distant detector, is the position space observable corresponding to th Weinberg soft photon pole in momentum space scattering amplitudes.

A hybrid asymptotic-modal analysis of the EM scattering by an open-ended S-shaped rectangular waveguide cavity

NASA Technical Reports Server (NTRS)

Law, P. H.; Burkholder, R. J.; Pathak, P. H.

1988-01-01

The electromagnetic fields (EM) backscatter from a 3-dimensional perfectly conducting S-shaped open-ended cavity with a planar interior termination is analyzed when it is illuminated by an external plane wave. The analysis is based on a self-consistent multiple scattering method which accounts for the multiple wave interactions between the open end and the interior termination. The scattering matrices which described the reflection and transmission coefficients of the waveguide modes reflected and transmitted at each junction between the different waveguide sections, as well at the scattering from the edges at the open end are found via asymptotic high frequency methods such as the geometrical and physical theories of diffraction used in conjunction with the equivalent current method. The numerical results for an S-shaped inlet cavity are compared with the backscatter from a straight inlet cavity; the backscattered patterns are different because the curvature of an S-shaped inlet cavity redistributes the energy reflected from the interior termination in a way that is different from a straight inlet cavity.

Les résonances d'un trou noir de Schwarzschild.

NASA Astrophysics Data System (ADS)

Bachelot, A.; Motet-Bachelot, A.

1993-09-01

This paper is devoted to the theoretical and computational investigations of the scattering frequencies of scalar, electromagnetic, gravitational waves around a spherical black hole. The authors adopt a time dependent approach: construction of wave operators for the hyperbolic Regge-Wheeler equation; asymptotic completeness; outgoing and incoming spectral representations; meromorphic continuation of the Heisenberg matrix; approximation by dumping and cut-off of the potentials and interpretation of the semi group Z(t) in the framework of the membrane paradigma. They develop a new procedure for the computation of the resonances by the spectral analysis of the transient scattered wave, based on Prony's algorithm.

Dispersive approach to two-photon exchange in elastic electron-proton scattering

DOE PAGES

Blunden, P. G.; Melnitchouk, W.

2017-06-14

We examine the two-photon exchange corrections to elastic electron-nucleon scattering within a dispersive approach, including contributions from both nucleon and Δ intermediate states. The dispersive analysis avoids off-shell uncertainties inherent in traditional approaches based on direct evaluation of loop diagrams, and guarantees the correct unitary behavior in the high energy limit. Using empirical information on the electromagnetic nucleon elastic and NΔ transition form factors, we compute the two-photon exchange corrections both algebraically and numerically. Finally, results are compared with recent measurements of e + p to e - p cross section ratios from the CLAS, VEPP-3 and OLYMPUS experiments.

The scattering of electromagnetic pulses by a slit in a conducting screen

NASA Technical Reports Server (NTRS)

Ackerknecht, W. E., III; Chen, C.-L.

1975-01-01

A direct method for calculating the impulse response of a slit in a conducting screen is presented which is derived specifically for the analysis of transient scattering by two-dimensional objects illuminated by a plane incident wave. The impulse response is obtained by assuming that the total response is composed of two sequences of diffracted waves. The solution is determined for the first two waves in one sequence by using Green's functions and the equivalence principle, for additional waves in the sequence by iteration, and for the other sequence by a transformation of coordinates. The cases of E-polarization and H-polarization are considered.

Stimulated Brillouin scattering in the field of a two-dimensionally localized pumping wave

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solikhov, D. K., E-mail: davlat56@mail.ru; Dvinin, S. A., E-mail: dvinin@phys.msu.ru

2016-06-15

Stimulated Brillouin scattering of electromagnetic waves in the field of a two-dimensionally localized pump wave at arbitrary scattering angles in the regime of forward scattering is analyzed. Spatial variations in the amplitudes of interacting waves are studied for different values of the pump field and different dimensions of the pump wave localization region. The intensity of scattered radiation is determined as a function of the scattering angle and the dimensions of the pump wave localization region. It is shown that the intensity increases with increasing scattering angle.

Detecting Stealth Dark Matter Directly through Electromagnetic Polarizability.

PubMed

Appelquist, T; Berkowitz, E; Brower, R C; Buchoff, M I; Fleming, G T; Jin, X-Y; Kiskis, J; Kribs, G D; Neil, E T; Osborn, J C; Rebbi, C; Rinaldi, E; Schaich, D; Schroeder, C; Syritsyn, S; Vranas, P; Weinberg, E; Witzel, O

2015-10-23

We calculate the spin-independent scattering cross section for direct detection that results from the electromagnetic polarizability of a composite scalar "stealth baryon" dark matter candidate, arising from a dark SU(4) confining gauge theory-"stealth dark matter." In the nonrelativistic limit, electromagnetic polarizability proceeds through a dimension-7 interaction leading to a very small scattering cross section for dark matter with weak-scale masses. This represents a lower bound on the scattering cross section for composite dark matter theories with electromagnetically charged constituents. We carry out lattice calculations of the polarizability for the lightest "baryon" states in SU(3) and SU(4) gauge theories using the background field method on quenched configurations. We find the polarizabilities of SU(3) and SU(4) to be comparable (within about 50%) normalized to the stealth baryon mass, which is suggestive for extensions to larger SU(N) groups. The resulting scattering cross sections with a xenon target are shown to be potentially detectable in the dark matter mass range of about 200-700 GeV, where the lower bound is from the existing LUX constraint while the upper bound is the coherent neutrino background. Significant uncertainties in the cross section remain due to the more complicated interaction of the polarizablity operator with nuclear structure; however, the steep dependence on the dark matter mass, 1/m(B)(6), suggests the observable dark matter mass range is not appreciably modified. We briefly highlight collider searches for the mesons in the theory as well as the indirect astrophysical effects that may also provide excellent probes of stealth dark matter.

Electromagnetic scattering by a uniaxial anisotropic sphere located in an off-axis Bessel beam.

PubMed

Qu, Tan; Wu, Zhen-Sen; Shang, Qing-Chao; Li, Zheng-Jun; Bai, Lu

2013-08-01

Electromagnetic scattering of a zero-order Bessel beam by an anisotropic spherical particle in the off-axis configuration is investigated. Based on the spherical vector wave functions, the expansion expression of the zero-order Bessel beam is derived, and its convergence is numerically discussed in detail. Utilizing the tangential continuity of the electromagnetic fields, the expressions of scattering coefficients are given. The effects of the conical angle of the wave vector components of the zero-order Bessel beam, the ratio of the radius of the sphere to the central spot radius of the zero-order Bessel beam, the shift of the beam waist center position along both the x and y axes, the permittivity and permeability tensor elements, and the loss of the sphere on the radar cross section (RCS) are numerically analyzed. It is revealed that the maximum RCS appears in the conical direction or neighboring direction when the sphere is illuminated by a zero-order Bessel beam. Furthermore, the RCS will decrease and the symmetry is broken with the shift of the beam waist center.

Electromagnetic and light scattering by nonspherical particles XVI

NASA Astrophysics Data System (ADS)

Berg, Matthew J.; Eversole, Jay D.; Kolokolova, Ludmilla; Mishchenko, Michael I.; Videen, Gorden

2017-11-01

The 16th Electromagnetic and Light Scattering Conference (ELS-XVI) was held in College Park, MD from 19-25 March 2017 (Fig. 1). This conference built on the success of the previous meetings held in Amsterdam (1995) [1], Helsinki (1997) [2], New York (1998) [3], Vigo (1999), Halifax (2000) [4], Gainesville (2002) [5], Bremen (2003) [6], Salobreña (2005) [7], St. Petersburg (2006) [8], Bodrum (2007) [9], Hatfield (2008) [10], Helsinki (2010) [11], Taormina (2011) [12], Lille (2013) [13], and Leipzig (2015) [14], as well as of three related workshops held in Bremen (1996, 1998) and Moscow (1997). As before, the main objective of this conference was to assemble scientists, engineers, and PhD students researching various aspects of electromagnetic scattering by particles and particle groups and to provide a stimulating atmosphere for in-depth discussions of theory, measurements, and applications. The conference featured 143 presentations by 132 registered participants from 18 countries. The program and the abstracts of conference presentations are available at the official conference web site https://www.giss.nasa.gov/staff/mmishchenko/ELS-XVI.

AN INTEGRAL EQUATION REPRESENTATION OF WIDE-BAND ELECTROMAGNETIC SCATTERING BY THIN SHEETS

EPA Science Inventory

An efficient, accurate numerical modeling scheme has been developed, based on the integral equation solution to compute electromagnetic (EM) responses of thin sheets over a wide frequency band. The thin-sheet approach is useful for simulating the EM response of a fracture system ...

A theoretical study of radar return and radiometric emission from the sea

NASA Technical Reports Server (NTRS)

Peake, W. H.

1972-01-01

The applicability of the various electromagnetic models of scattering from the ocean are reviewed. These models include the small perturbation method, the geometric optics solution, the composite model, and the exact integral equation solution. The restrictions on the electromagnetic models are discussed.

The Coupling of Finite Element and Integral Equation Representations for Efficient Three-Dimensional Modeling of Electromagnetic Scattering and Radiation

NASA Technical Reports Server (NTRS)

Cwik, Tom; Zuffada, Cinzia; Jamnejad, Vahraz

1996-01-01

Finite element modeling has proven useful for accurtely simulating scattered or radiated fields from complex three-dimensional objects whose geometry varies on the scale of a fraction of a wavelength.

Stimulated Brillouin scatter in a magnetized ionospheric plasma.

PubMed

Bernhardt, P A; Selcher, C A; Lehmberg, R H; Rodriguez, S P; Thomason, J F; Groves, K M; McCarrick, M J; Frazer, G J

2010-04-23

High power electromagnetic waves transmitted from the HAARP facility in Alaska can excite low-frequency electrostatic waves by magnetized stimulated Brillouin scatter. Either an ion-acoustic wave with a frequency less than the ion cyclotron frequency (f(CI)) or an electrostatic ion cyclotron (EIC) wave just above f(CI) can be produced. The coupled equations describing the magnetized stimulated Brillouin scatter instability show that the production of both ion-acoustic and EIC waves is strongly influenced by the wave propagation relative to the background magnetic field. Experimental observations of stimulated electromagnetic emissions using the HAARP transmitter have confirmed that only ion-acoustic waves are excited for propagation along the magnetic zenith and that EIC waves can only be detected with oblique propagation angles. The ion composition can be obtained from the measured EIC frequency.

Target deception jamming method against spaceborne synthetic aperture radar using electromagnetic scattering

NASA Astrophysics Data System (ADS)

Sun, Qingyang; Shu, Ting; Tang, Bin; Yu, Wenxian

2018-01-01

A method is proposed to perform target deception jamming against spaceborne synthetic aperture radar. Compared with the traditional jamming methods using deception templates to cover the target or region of interest, the proposed method aims to generate a verisimilar deceptive target in various attitude with high fidelity using the electromagnetic (EM) scattering. Based on the geometrical model for target deception jamming, the EM scattering data from the deceptive target was first simulated by applying an EM calculation software. Then, the proposed jamming frequency response (JFR) is calculated offline by further processing. Finally, the deception jamming is achieved in real time by a multiplication between the proposed JFR and the spectrum of intercepted radar signals. The practical implementation is presented. The simulation results prove the validity of the proposed method.

Electromagnetic field redistribution induced selective plasmon driven surface catalysis in metal nanowire-film systems

PubMed Central

Pan, Liang; Huang, Yingzhou; Yang, Yanna; Xiong, Wen; Chen, Guo; Su, Xun; Wei, Hua; Wang, Shuxia; Wen, Weijia

2015-01-01

For the novel interpretation of Raman spectrum from molecule at metal surface, the plasmon driven surface catalysis (PDSC) reactions have become an interesting topic in the research field of surface enhanced Raman scattering (SERS). In this work, the selective PDSC reactions of p,p’-dimercaptoazobenzene (DMAB) produced from para-aminothiophenol (PATP) or 4-nitrobenzenethiol (4NBT) were demonstrated in the Ag nanowires dimer-Au film systems. The different SERS spectra collected at individual part and adjacent part of the same nanowire-film system pointed out the importance of the electromagnetic field redistribution induced by image charge on film in this selective surface catalysis, which was confirmed by the simulated electromagnetic simulated electro- magnetic field distributions. Our result indicated this electromagnetic field redistribution induced selective surface catalysis was largely affected by the polarization and wavelength of incident light but slightly by the difference in diameters between two nanowires. Our work provides a further understanding of PDSC reaction in metal nanostructure and could be a deep support for the researches on surface catalysis and surface analysis. PMID:26601698

A numerical study of electromagnetic scattering from ocean like surfaces

NASA Technical Reports Server (NTRS)

Lentz, R. R.

1972-01-01

The integral equations describing electromagnetic scattering from one dimensional conducting surfaces are formulated and numerical results are presented. The results are compared with those obtained using approximate methods such as physical optics, geometrical optics, and perturbation theory. The integral equation solutions show that the surface radius of curvature must be greater than 2.5 wavelengths for either the physical optics or geometric optics to give satisfactory results. It has also been shown that perturbation theory agrees with the exact fields as long as the root mean square surface roughness is less than one-tenth of a wavelength.

A class of invisible inhomogeneous media and the control of electromagnetic waves

NASA Astrophysics Data System (ADS)

Vial, B.; Liu, Y.; Horsley, S. A. R.; Philbin, T. G.; Hao, Y.

2016-12-01

We propose a general method to arbitrarily manipulate an electromagnetic wave propagating in a two-dimensional medium, without introducing any scattering. This leads to a whole class of isotropic spatially varying permittivity and permeability profiles that are invisible while shaping the field magnitude and/or phase. In addition, we propose a metamaterial structure working in the infrared that demonstrates deep subwavelength control of the electric field amplitude and strong reduction of the scattering. This work offers an alternative strategy to achieve invisibility with isotropic materials and paves the way for tailoring the propagation of light at the nanoscale.

Plane-wave scattering by self-complementary metasurfaces in terms of electromagnetic duality and Babinet's principle

NASA Astrophysics Data System (ADS)

Nakata, Yosuke; Urade, Yoshiro; Nakanishi, Toshihiro; Kitano, Masao

2013-11-01

We investigate theoretically electromagnetic plane-wave scattering by self-complementary metasurfaces. By using Babinet's principle extended to metasurfaces with resistive elements, we show that the frequency-independent transmission and reflection are realized for normal incidence of a circularly polarized plane wave onto a self-complementary metasurface, even if there is diffraction. Next, we consider two special classes of self-complementary metasurfaces. We show that self-complementary metasurfaces with rotational symmetry can act as coherent perfect absorbers, and those with translational symmetry compatible with their self-complementarity can split the incident power equally, even for oblique incidences.

Observation of unidirectional backscattering-immune topological electromagnetic states.

PubMed

Wang, Zheng; Chong, Yidong; Joannopoulos, J D; Soljacić, Marin

2009-10-08

One of the most striking phenomena in condensed-matter physics is the quantum Hall effect, which arises in two-dimensional electron systems subject to a large magnetic field applied perpendicular to the plane in which the electrons reside. In such circumstances, current is carried by electrons along the edges of the system, in so-called chiral edge states (CESs). These are states that, as a consequence of nontrivial topological properties of the bulk electronic band structure, have a unique directionality and are robust against scattering from disorder. Recently, it was theoretically predicted that electromagnetic analogues of such electronic edge states could be observed in photonic crystals, which are materials having refractive-index variations with a periodicity comparable to the wavelength of the light passing through them. Here we report the experimental realization and observation of such electromagnetic CESs in a magneto-optical photonic crystal fabricated in the microwave regime. We demonstrate that, like their electronic counterparts, electromagnetic CESs can travel in only one direction and are very robust against scattering from disorder; we find that even large metallic scatterers placed in the path of the propagating edge modes do not induce reflections. These modes may enable the production of new classes of electromagnetic device and experiments that would be impossible using conventional reciprocal photonic states alone. Furthermore, our experimental demonstration and study of photonic CESs provides strong support for the generalization and application of topological band theories to classical and bosonic systems, and may lead to the realization and observation of topological phenomena in a generally much more controlled and customizable fashion than is typically possible with electronic systems.

Fast Multipole / Wavelet-IML Hybrids for Electromagnetic Analysis

DTIC Science & Technology

2005-07-20

this project and honors/awards/degrees received - Mingyu Lu (Ph.D. granted in August 21, 2002; after that Post-doctoral Fellow on this project; he...Lu, K. Aygun, Mingyu Lu, and E. Michielssen, “Low frequency PWTD kernels”, To be submitted to Journal of Computational Physics, draft available upon...transient scattering phenomena involving large surfaces using integral equations. 18. M. Lu, K. Aygun, Mingyu Lu, and E. Michielssen, “Low frequency

Development of New Methods for Predicting the Bistatic Electromagnetic Scattering from Absorbing Shapes

DTIC Science & Technology

1990-01-01

least-squares sense by adding a penalty term proportional to the square of the divergence to the variational principle At the start of this project... principle required for stable solutions of the electromagnetic field: It must be possible to express the basis functions used in the finite element method as... principle to derive several different methods for computing stable solutions to electromagnetic field problems. To understand above principle , notice that

Depolarization and Scattering of Electromagnetic Waves. Appendices.

DTIC Science & Technology

1986-06-30

for both specular point scattering and Bragg scattering in a self-consistent manner is used to express the total cross section of the flake as a...by Arbitrarily Oriented Composite Rough Surfaces. In this work the full wave approach is used to determine the modu- lations of the like and cross...analyze multiple scattering using the equation of radiative transfer with the general Stokes’ parameters. Our ultimate goal is to develop codes which will

On electromagnetic and quantum invisibility

NASA Astrophysics Data System (ADS)

Mundru, Pattabhiraju Chowdary

The principle objective of this dissertation is to investigate the fundamental properties of electromagnetic wave interactions with artificially fabricated materials i.e., metamaterials for application in advanced stealth technology called electromagnetic cloaking. The main goal is to theoretically design a metamaterial shell around an object that completely eliminates the dipolar and higher order multipolar scattering, thus making the object invisible. In this context, we developed a quasi-effective medium theory that determines the optical properties of multi-layered-composites beyond the quasi-static limit. The proposed theory exactly reproduces the far-field scattering/extinction cross sections through an iterative process in which mode-dependent quasi-effective impedances of the composite system are introduced. In the large wavelength limit, our theory is consistent with Maxwell-Garnett formalism. Possible applications in determining the hybridization particle resonances of multi-shell structures and electromagnetic cloaking are identified. This dissertation proposes a multi-shell generic cloaking system. A transparency condition independent of the object's optical and geometrical properties is proposed in the quasi-static regime of operation. The suppression of dipolar scattering is demonstrated in both cylindrically and spherically symmetric systems. A realistic tunable low-loss shell design is proposed based on the composite metal-dielectric shell. The effects due to dissipation and dispersion on the overall scattering cross-section are thoroughly evaluated. It is shown that a strong reduction of scattering by a factor of up to 103 can be achieved across the entire optical spectrum. Full wave numerical simulations for complex shaped particle are performed to validate the analytical theory. The proposed design does not require optical magnetism and is generic in the sense that it is independent of the object's material and geometrical properties. A generic quantum cloak analogous to the optical cloak is also proposed. The transparency conditions required for the shells to cloak an object impinged by a low energy beam of particles are derived. A realistic cloaking system with semiconductor material shells is studied.

Resonant scattering from a two-dimensional honeycomb PT dipole structure

NASA Astrophysics Data System (ADS)

Markoš, P.; Kuzmiak, V.

2018-05-01

We studied numerically the electromagnetic response of the finite periodic structure consisting of the PT dipoles represented by two infinitely long, parallel cylinders with the opposite sign of the imaginary part of a refractive index, which are centered at the positions of a two-dimensional honeycomb lattice. We observed that the total scattered energy reveals a series of sharp resonances at which the energy increases by two orders of magnitude and an incident wave is scattered only in a few directions given by spatial symmetry of the periodic structure. We explain this behavior by analysis of the complex frequency spectra associated with an infinite honeycomb array of the PT dipoles and identify the lowest resonance with the broken PT -symmetry mode formed by a doubly degenerate pair with complex conjugate eigenfrequencies corresponding to the K point of the reciprocal lattice.

Coding metasurface for broadband microwave scattering reduction with optical transparency.

PubMed

Chen, Ke; Cui, Li; Feng, Yijun; Zhao, Junming; Jiang, Tian; Zhu, Bo

2017-03-06

Metasurfaces have promised great possibilities in full control of the electromagnetic wavefront by spatially manipulating the phase characteristics across the interface. Here, we report a scheme to realize broadband backward scattering reduction through diffusion-like microwave reflection by utilizing a flexible indium-tin-oxide (ITO)-based ultrathin coding metasurface (less than 0.1 wavelength thick) with high optical transparence. The diffusion-like scattering is caused by the destructive interference of the scattered far-field electromagnetic wave, which is further attributed to the randomly distributed reflection phases on the metasurface composed of pre-designed meta-atoms arranged with a computer-generated pseudorandom coding sequence. Both simulation and measurement on fabricated prototype sample have been carried out to validate its performance, demonstrating a polarization-independent broadband (nearly from 8 GHz to 15 GHz) 10 dB scattering reduction with good oblique performance. The excellent performances can also be preserved to conformal cases when the flexible metasurface is uniformly wrapped around a metallic cylinder. The proposed metasurface may create new opportunities to tailor the exotic microwave scattering features with simultaneously high transmittance in visible frequencies, which could provide crucial benefits in many practical uses, such as window and solar panel applications.

Electromagnetic scattering by a straight thin wire

NASA Technical Reports Server (NTRS)

Shamansky, Harry T.; Dominek, Allen K.; Peters, Leon, Jr.

1989-01-01

The traveling-wave energy, which multiply diffracts on a straight thin wire, is represented as a sum of terms, each with a distinct physical meaning, that can be individually examined in the time domain. Expressions for each scattering mechanism on a straight thin wire are cast in the form of four basic electromagnetic wave concepts: diffraction, attachment, launch, and reflection. Using the basic mechanisms from P. Ya. Ufimtsev (1962), each of the scattering mechanisms is included into the total scattered field for the straight thin wire. Scattering as a function of angle and frequency is then compared to the moment-method solution. These analytic expressions are then extended to a lossy wire with a simple approximate modification using the propagation velocity on the wire as derived from the Sommerfeld wave on a straight lossy wire. Both the perfectly conducting and lossy wire solutions are compared to moment-method results, and excellent agreement is found. As is common with asymptotic solutions, when the electrical length of wire is smaller than 0.2 lambda the results lose accuracy. The expressions modified to approximate the scattering for the lossy thin wire yield excellent agreement even for lossy wires where the wire radius is on the order of skin depth.

Scattering by multiple cylinders located on both sides of an interface

NASA Astrophysics Data System (ADS)

Lee, Siu-Chun

2018-07-01

The solution for scattering by multiple parallel infinite cylinders located in adjacent half spaces with dissimilar refractive index is presented in this paper. The incident radiation is an arbitrarily polarized plane wave propagating in the upper half space in the plane perpendicular to the axis of the cylinders. The formulation of the electromagnetic field vectors utilized Hertz potentials that are expressed in terms of an expansion of cylindrical wave functions. It accounts for the near-field multiple scattering, Fresnel effect at the interface, and interaction between cylinders in both half spaces. Analytical formulas are derived for the electromagnetic field and Poynting vector in the far-field. The present solution provides the theoretical framework for deducing the solutions for scattering by cylinders located on either side of an interface irradiated by a propagating or an evanescent incident wave. Deduction of these solutions from the present formulation is demonstrated. Numerical results are presented to illustrate the frustration of total internal reflection and scattering of light beyond the critical angle by nanocylinders located in either or both half spaces.

Electromagnetic Model Reliably Predicts Radar Scattering Characteristics of Airborne Organisms

NASA Astrophysics Data System (ADS)

Mirkovic, Djordje; Stepanian, Phillip M.; Kelly, Jeffrey F.; Chilson, Phillip B.

2016-10-01

The radar scattering characteristics of aerial animals are typically obtained from controlled laboratory measurements of a freshly harvested specimen. These measurements are tedious to perform, difficult to replicate, and typically yield only a small subset of the full azimuthal, elevational, and polarimetric radio scattering data. As an alternative, biological applications of radar often assume that the radar cross sections of flying animals are isotropic, since sophisticated computer models are required to estimate the 3D scattering properties of objects having complex shapes. Using the method of moments implemented in the WIPL-D software package, we show for the first time that such electromagnetic modeling techniques (typically applied to man-made objects) can accurately predict organismal radio scattering characteristics from an anatomical model: here the Brazilian free-tailed bat (Tadarida brasiliensis). The simulated scattering properties of the bat agree with controlled measurements and radar observations made during a field study of bats in flight. This numerical technique can produce the full angular set of quantitative polarimetric scattering characteristics, while eliminating many practical difficulties associated with physical measurements. Such a modeling framework can be applied for bird, bat, and insect species, and will help drive a shift in radar biology from a largely qualitative and phenomenological science toward quantitative estimation of animal densities and taxonomic identification.

Electromagnetic Model Reliably Predicts Radar Scattering Characteristics of Airborne Organisms

PubMed Central

Mirkovic, Djordje; Stepanian, Phillip M.; Kelly, Jeffrey F.; Chilson, Phillip B.

2016-01-01

The radar scattering characteristics of aerial animals are typically obtained from controlled laboratory measurements of a freshly harvested specimen. These measurements are tedious to perform, difficult to replicate, and typically yield only a small subset of the full azimuthal, elevational, and polarimetric radio scattering data. As an alternative, biological applications of radar often assume that the radar cross sections of flying animals are isotropic, since sophisticated computer models are required to estimate the 3D scattering properties of objects having complex shapes. Using the method of moments implemented in the WIPL-D software package, we show for the first time that such electromagnetic modeling techniques (typically applied to man-made objects) can accurately predict organismal radio scattering characteristics from an anatomical model: here the Brazilian free-tailed bat (Tadarida brasiliensis). The simulated scattering properties of the bat agree with controlled measurements and radar observations made during a field study of bats in flight. This numerical technique can produce the full angular set of quantitative polarimetric scattering characteristics, while eliminating many practical difficulties associated with physical measurements. Such a modeling framework can be applied for bird, bat, and insect species, and will help drive a shift in radar biology from a largely qualitative and phenomenological science toward quantitative estimation of animal densities and taxonomic identification. PMID:27762292

Electromagnetic Model Reliably Predicts Radar Scattering Characteristics of Airborne Organisms.

PubMed

Mirkovic, Djordje; Stepanian, Phillip M; Kelly, Jeffrey F; Chilson, Phillip B

2016-10-20

The radar scattering characteristics of aerial animals are typically obtained from controlled laboratory measurements of a freshly harvested specimen. These measurements are tedious to perform, difficult to replicate, and typically yield only a small subset of the full azimuthal, elevational, and polarimetric radio scattering data. As an alternative, biological applications of radar often assume that the radar cross sections of flying animals are isotropic, since sophisticated computer models are required to estimate the 3D scattering properties of objects having complex shapes. Using the method of moments implemented in the WIPL-D software package, we show for the first time that such electromagnetic modeling techniques (typically applied to man-made objects) can accurately predict organismal radio scattering characteristics from an anatomical model: here the Brazilian free-tailed bat (Tadarida brasiliensis). The simulated scattering properties of the bat agree with controlled measurements and radar observations made during a field study of bats in flight. This numerical technique can produce the full angular set of quantitative polarimetric scattering characteristics, while eliminating many practical difficulties associated with physical measurements. Such a modeling framework can be applied for bird, bat, and insect species, and will help drive a shift in radar biology from a largely qualitative and phenomenological science toward quantitative estimation of animal densities and taxonomic identification.

Detecting Stealth Dark Matter Directly through Electromagnetic Polarizability

DOE PAGES

Appelquist, T.; Berkowitz, E.; Brower, R. C.; ...

2015-10-23

We calculate the spin-independent scattering cross section for direct detection that results from the electromagnetic polarizability of a composite scalar “stealth baryon” dark matter candidate, arising from a dark SU(4) confining gauge theory—“stealth dark matter.” In the nonrelativistic limit, electromagnetic polarizability proceeds through a dimension-7 interaction leading to a very small scattering cross section for dark matter with weak-scale masses. This represents a lower bound on the scattering cross section for composite dark matter theories with electromagnetically charged constituents. We carry out lattice calculations of the polarizability for the lightest “baryon” states in SU(3) and SU(4) gauge theories using themore » background field method on quenched configurations. We find the polarizabilities of SU(3) and SU(4) to be comparable (within about 50%) normalized to the stealth baryon mass, which is suggestive for extensions to larger SU(N) groups. The resulting scattering cross sections with a xenon target are shown to be possibly detectable in the dark matter mass range of about 200–700 GeV, where the lower bound is from the existing LUX constraint while the upper bound is the coherent neutrino background. Significant uncertainties in the cross section remain due to the more complicated interaction of the polarizablity operator with nuclear structure; however, the steep dependence on the dark matter mass, 1/m 6 B, suggests the observable dark matter mass range is not appreciably modified. We highlight collider searches for the mesons in the theory as well as the indirect astrophysical effects that may also provide excellent probes of stealth dark matter.« less

Oblique scattering from radially inhomogeneous dielectric cylinders: An exact Volterra integral equation formulation

NASA Astrophysics Data System (ADS)

Tsalamengas, John L.

2018-07-01

We study plane-wave electromagnetic scattering by radially and strongly inhomogeneous dielectric cylinders at oblique incidence. The method of analysis relies on an exact reformulation of the underlying field equations as a first-order 4 × 4 system of differential equations and on the ability to restate the associated initial-value problem in the form of a system of coupled linear Volterra integral equations of the second kind. The integral equations so derived are discretized via a sophisticated variant of the Nyström method. The proposed method yields results accurate up to machine precision without relying on approximations. Numerical results and case studies ably demonstrate the efficiency and high accuracy of the algorithms.

Far-Field Lorenz-Mie Scattering in an Absorbing Host Medium: Theoretical Formalism and FORTRAN Program

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Yang, Ping

2018-01-01

In this paper we make practical use of the recently developed first-principles approach to electromagnetic scattering by particles immersed in an unbounded absorbing host medium. Specifically, we introduce an actual computational tool for the calculation of pertinent far-field optical observables in the context of the classical Lorenzâ€"Mie theory. The paper summarizes the relevant theoretical formalism, explains various aspects of the corresponding numerical algorithm, specifies the input and output parameters of a FORTRAN program available at https://www.giss.nasa.gov/staff/mmishchenko/Lorenz-Mie.html, and tabulates benchmark results useful for testing purposes. This public-domain FORTRAN program enables one to solve the following two important problems: (i) simulate theoretically the reading of a remote well-collimated radiometer measuring electromagnetic scattering by an individual spherical particle or a small random group of spherical particles; and (ii) compute the single-scattering parameters that enter the vector radiative transfer equation derived directly from the Maxwell equations.

Broadband diffuse terahertz wave scattering by flexible metasurface with randomized phase distribution

PubMed Central

Zhang, Yin; Liang, Lanju; Yang, Jing; Feng, Yijun; Zhu, Bo; Zhao, Junming; Jiang, Tian; Jin, Biaobing; Liu, Weiwei

2016-01-01

Suppressing specular electromagnetic wave reflection or backward radar cross section is important and of broad interests in practical electromagnetic engineering. Here, we present a scheme to achieve broadband backward scattering reduction through diffuse terahertz wave reflection by a flexible metasurface. The diffuse scattering of terahertz wave is caused by the randomized reflection phase distribution on the metasurface, which consists of meta-particles of differently sized metallic patches arranged on top of a grounded polyimide substrate simply through a certain computer generated pseudorandom sequence. Both numerical simulations and experimental results demonstrate the ultralow specular reflection over a broad frequency band and wide angle of incidence due to the re-distribution of the incident energy into various directions. The diffuse scattering property is also polarization insensitive and can be well preserved when the flexible metasurface is conformably wrapped on a curved reflective object. The proposed design opens up a new route for specular reflection suppression, and may be applicable in stealth and other technology in the terahertz spectrum. PMID:27225031

Calculated shape dependence of electromagnetic field in tip-enhanced Raman scattering by using a monopole antenna model

NASA Astrophysics Data System (ADS)

Kitahama, Yasutaka; Itoh, Tamitake; Suzuki, Toshiaki

2018-05-01

To evaluate the shape of an Ag tip with regard to tip-enhanced Raman scattering (TERS) signal, the enhanced electromagnetic (EM) field and scattering spectrum, arising from surface plasmon resonance at the apex of the tip, were calculated using a finite-difference time domain (FDTD) method. In the calculated forward scattering spectra from the smooth Ag tip, the band appeared within the visible region, similar to the experimental results and calculation for a corrugated Ag cone. In the FDTD calculation of TERS, the Ag tip acting as a monopole antenna was adopted by insertion of a perfect electric conductor between the root of the tip and a top boundary surface of the calculation space. As a result, the EM field was only enhanced at the apex. The shape dependence i.e. the EM field calculated at the apex with various curvatures on the different tapered tips, obtained using the monopole antenna model, was different from that simulated using a conventional dipole antenna model.

Broadband diffuse terahertz wave scattering by flexible metasurface with randomized phase distribution.

PubMed

Zhang, Yin; Liang, Lanju; Yang, Jing; Feng, Yijun; Zhu, Bo; Zhao, Junming; Jiang, Tian; Jin, Biaobing; Liu, Weiwei

2016-05-26

Suppressing specular electromagnetic wave reflection or backward radar cross section is important and of broad interests in practical electromagnetic engineering. Here, we present a scheme to achieve broadband backward scattering reduction through diffuse terahertz wave reflection by a flexible metasurface. The diffuse scattering of terahertz wave is caused by the randomized reflection phase distribution on the metasurface, which consists of meta-particles of differently sized metallic patches arranged on top of a grounded polyimide substrate simply through a certain computer generated pseudorandom sequence. Both numerical simulations and experimental results demonstrate the ultralow specular reflection over a broad frequency band and wide angle of incidence due to the re-distribution of the incident energy into various directions. The diffuse scattering property is also polarization insensitive and can be well preserved when the flexible metasurface is conformably wrapped on a curved reflective object. The proposed design opens up a new route for specular reflection suppression, and may be applicable in stealth and other technology in the terahertz spectrum.

Far-field Lorenz-Mie scattering in an absorbing host medium: Theoretical formalism and FORTRAN program

NASA Astrophysics Data System (ADS)

Mishchenko, Michael I.; Yang, Ping

2018-01-01

In this paper we make practical use of the recently developed first-principles approach to electromagnetic scattering by particles immersed in an unbounded absorbing host medium. Specifically, we introduce an actual computational tool for the calculation of pertinent far-field optical observables in the context of the classical Lorenz-Mie theory. The paper summarizes the relevant theoretical formalism, explains various aspects of the corresponding numerical algorithm, specifies the input and output parameters of a FORTRAN program available at https://www.giss.nasa.gov/staff/mmishchenko/Lorenz-Mie.html, and tabulates benchmark results useful for testing purposes. This public-domain FORTRAN program enables one to solve the following two important problems: (i) simulate theoretically the reading of a remote well-collimated radiometer measuring electromagnetic scattering by an individual spherical particle or a small random group of spherical particles; and (ii) compute the single-scattering parameters that enter the vector radiative transfer equation derived directly from the Maxwell equations.

Algorithm development for Maxwell's equations for computational electromagnetism

NASA Technical Reports Server (NTRS)

Goorjian, Peter M.

1990-01-01

A new algorithm has been developed for solving Maxwell's equations for the electromagnetic field. It solves the equations in the time domain with central, finite differences. The time advancement is performed implicitly, using an alternating direction implicit procedure. The space discretization is performed with finite volumes, using curvilinear coordinates with electromagnetic components along those directions. Sample calculations are presented of scattering from a metal pin, a square and a circle to demonstrate the capabilities of the new algorithm.

Wave multiple scattering by a finite number of unclosed circular cylinders

NASA Technical Reports Server (NTRS)

Veliyev, E. I.; Veremey, V. V.

1984-01-01

The boundary value problem of plane H-polarized electromagnetic wave multiple scattering by a finite number of unclosed circular cylinders is solved. The solution is obtained by two different methods: the method of successive scattering and the method of partial matrix inversion for simultaneous dual equations. The advantages of the successive scattering method are shown. Computer calculations of the suface currents and the total cross section are presented for the structure of two screens.

Geophysical Remote Sensing Using the HF Pumped Stimulated Brillouin Scatter (SBS) Emission Lines Produced by HAARP

NASA Astrophysics Data System (ADS)

Bernhardt, P. A.; Selcher, C. A.

2009-12-01

An ordinary or extraordinary mode electromagnetic wave can decay into a low frequency electrostatic wave and a scattered electromagnetic wave by a process called stimulated Brillouin scatter (SBS). The low frequency wave can be either an ion acoustic wave (IA) or an electrostatic ion cyclotron (EIC) wave. The first detection ion acoustic waves by this process during ionospheric modification with high power radio waves was reported by Norin et al. (2009) using the HAARP transmitter in Alaska. The first detection of the electrostatic ion cyclotron waves is reported here using HAARP during the March 2009 campaign. Subsequent experiments have provided additional verification of the SBS process and quantitative interpretation of the scattered wave frequency offsets to yield measurements of the electron temperatures in the heated ionosphere by Bernhardt et al. (2009). Using the SBS technique to generate ion acoustic waves, electron temperatures between 3000 and 4000 K were measured over the HAARP facility. The matching conditions for decay of the high frequency pump wave show that in addition to the production of an ion-acoustic wave, an electrostatic ion cyclotron wave can produced by the generalized SBS processes only if the pump waves makes a large angle with the magnetic field. When the EIC mode is produced, it is seen as a narrow of stimulated electromagnetic emissions at the ion cyclotron frequency. Occasionally, multiple lines are seen and analyzed to yield the relative abundance of oxygen, and molecular ions in the lower ionosphere. This ion mass spectrometer interpretation of the SBS data is new to the field of ionosphere remote sensing. In addition, based on the matching condition theory, the first profiles of the scattered wave amplitude are produced using the stimulated Brillouin scatter (SBS) matching conditions. These profiles are consistent with maximum ionospheric interactions at the upper-hybrid resonance height and at a region just below the plasma resonance altitude where the pump wave electric fields reach their maximum values. All of these measurements of the HF modified ionosphere are made possible at HAARP because of (1) the recently increased transmitter power to 3.6 MW into the large antenna array and (2) the new digital receiver diagnostics that allow up to 100 dB dynamic range in the stimulated electromagnetic emission measurements. Paul A. Bernhardt, Craig A. Selcher, Robert H. Lehmberg, Serafin Rodriguez, Joe Thomason, Mike McCarrick, Gordon Frazer, Determination of the Electron Temperature in the Modified Ionosphere over HAARP Using the HF Pumped Stimulated Brillouin Scatter (SBS) Emission Lines, Annales Geophysicae, in press, 2009. Norin, L., Leyser, T. B., Nordblad, E., Thidé, B., and McCarrick, M., Unprecedentedly strong and narrow electromagnetic emissions stimulated by high-frequency radio waves in the ionosphere, Phys. Rev. Lett., 102, 065003, 2009.

Stimulated Brillouin Scatter in a Magnetized Ionospheric Plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernhardt, P. A.; Selcher, C. A.; Lehmberg, R. H.

2010-04-23

High power electromagnetic waves transmitted from the HAARP facility in Alaska can excite low-frequency electrostatic waves by magnetized stimulated Brillouin scatter. Either an ion-acoustic wave with a frequency less than the ion cyclotron frequency (f{sub CI}) or an electrostatic ion cyclotron (EIC) wave just above f{sub CI} can be produced. The coupled equations describing the magnetized stimulated Brillouin scatter instability show that the production of both ion-acoustic and EIC waves is strongly influenced by the wave propagation relative to the background magnetic field. Experimental observations of stimulated electromagnetic emissions using the HAARP transmitter have confirmed that only ion-acoustic waves aremore » excited for propagation along the magnetic zenith and that EIC waves can only be detected with oblique propagation angles. The ion composition can be obtained from the measured EIC frequency.« less

Invisibility and Cloaking: Origins, Present, and Future Perspectives

NASA Astrophysics Data System (ADS)

Fleury, Romain; Monticone, Francesco; Alù, Andrea

2015-09-01

The development of metamaterials, i.e., artificially structured materials that interact with waves in unconventional ways, has revolutionized our ability to manipulate the propagation of electromagnetic waves and their interaction with matter. One of the most exciting applications of metamaterial science is related to the possibility of totally suppressing the scattering of an object using an invisibility cloak. Here, we review the available methods to make an object undetectable to electromagnetic waves, and we highlight the outstanding challenges that need to be addressed in order to obtain a fully functional coating capable of suppressing the total scattering of an object. Our outlook discusses how, while passive linear cloaks are fundamentally limited in terms of bandwidth of operation and overall scattering suppression, active and/or nonlinear cloaks hold the promise to overcome, at least partially, some of these limitations.

Studies of Scattering, Reflectivity, and Transmitivity in WBAN Channel: Feasibility of Using UWB

PubMed Central

Kabir, Md. Humaun; Ashrafuzzaman, Kazi; Chowdhury, M. Sanaullah; Kwak, Kyung Sup

2010-01-01

The Wireless Personal Area Network (WPAN) is one of the fledging paradigms that the next generation of wireless systems is sprouting towards. Among them, a more specific category is the Wireless Body Area Network (WBAN) used for health monitoring. On the other hand, Ultra-Wideband (UWB) comes with a number of desirable features at the physical layer for wireless communications. One big challenge in adoption of UWB in WBAN is the fact that signals get attenuated exponentially. Due to the intrinsic structural complexity in human body, electromagnetic waves show a profound variation during propagation through it. The reflection and transmission coefficients of human body are highly dependent upon the dielectric constants as well as upon the frequency. The difference in structural materials such as fat, muscles and blood essentially makes electromagnetic wave attenuation to be different along the way. Thus, a complete characterization of body channel is a challenging task. The connection between attenuation and frequency of the signal makes the investigation of UWB in WBAN an interesting proposition. In this paper, we study analytically the impact of body channels on electromagnetic signal propagation with reference to UWB. In the process, scattering, reflectivity and transmitivity have been addressed with analysis of approximate layer-wise modeling, and with numerical depictions. Pulses with Gaussian profile have been employed in our analysis. It shows that, under reasonable practical approximations, the human body channel can be modeled in layers so as to have the effects of total reflections or total transmissions in certain frequency bands. This could help decide such design issues as antenna characteristics of implant devices for WBAN employing UWB. PMID:22219673

Scattering of Light and Surface Plasmon Polaritons from Rough Surfaces

DTIC Science & Technology

2013-06-14

Scattering of an electromagnetic wave from a slightly random dielectric surface: Yoneda peak and Brewster angle in incoherent scattering.” Waves...device applications. Thus, the negative refraction of a surface plasmon polariton was studied in two papers. In the first [1], all- angle negative... angle of incidence, measured counterclockwise from the negative x1 axis, is . The surface plasmon polariton of frequency transmitted through the

Scattering and Imaging of Nonlinearly Loaded Antenna Structures in Half-Space and Complex-Room Environments

DTIC Science & Technology

2014-09-01

ABSTRACT The electromagnetic scattering responses of nonlinearly loaded antenna structures excited by single- tone or multi- tone incident fields are...3  Fig. 2 Monostatic scattered electric field strength for center array element: a) Single- tone excitation at 300 MHz...three diode-loaded targets and b) Two- tone excitation at 300 MHz and 305 MHz; two varactor-loaded targets

Electromagnetic scattering from microwave absorbers - Laboratory verification of the coupled wave theory

NASA Technical Reports Server (NTRS)

Gasiewski, A. J.; Jackson, D. M.

1992-01-01

W-band measurements of the bistatic scattering function of some common microwave absorbing structures, including periodic wedge-type and pyramid-type iron-epoxy calibration loads and flat carbon-foam 'Echosorb' samples, were made using a network analyzer interface to a focused-lens scattering range. Swept frequency measurements over the 75-100 GHz band revealed specular and Bragg reflection characteristics in the measured data.

Backscattering from a Gaussian distributed, perfectly conducting, rough surface

NASA Technical Reports Server (NTRS)

Brown, G. S.

1977-01-01

The problem of scattering by random surfaces possessing many scales of roughness is analyzed. The approach is applicable to bistatic scattering from dielectric surfaces, however, this specific analysis is restricted to backscattering from a perfectly conducting surface in order to more clearly illustrate the method. The surface is assumed to be Gaussian distributed so that the surface height can be split into large and small scale components, relative to the electromagnetic wavelength. A first order perturbation approach is employed wherein the scattering solution for the large scale structure is perturbed by the small scale diffraction effects. The scattering from the large scale structure is treated via geometrical optics techniques. The effect of the large scale surface structure is shown to be equivalent to a convolution in k-space of the height spectrum with the following: the shadowing function, a polarization and surface slope dependent function, and a Gaussian factor resulting from the unperturbed geometrical optics solution. This solution provides a continuous transition between the near normal incidence geometrical optics and wide angle Bragg scattering results.

High speed data transmission coaxial-cable in the space communication system

NASA Astrophysics Data System (ADS)

Su, Haohang; Huang, Jing

2018-01-01

An effective method is proved based on the scattering parameter of high speed 8-core coaxial-cable measured by vector network analyzer, and the semi-physical simulation is made to receive the eye diagram at different data transmission rate. The result can be apply to analysis decay and distortion of the signal through the coaxial-cable at high frequency, and can extensively design for electromagnetic compatibility of high-speed data transmission system.

Analytical evaluation of ILM sensors. Volume 2: Appendices

NASA Technical Reports Server (NTRS)

Kirk, R. J.

1975-01-01

The applicability of various sensing concepts to independent landing monitor systems was analyzed. Microwave landing system MLS accuracy requirements are presented along with a description of MLS airborne equipment. Computer programs developed during the analysis are described and include: a mathematical computer model for use in the performance assessment of reconnaissance sensor systems; a theoretical formulation of electromagnetic scattering to generate data at high incidence angles; atmospheric attenuation of microwaves; and microwave radiometry, programs

Solution of electromagnetic scattering and radiation problems using a spectral domain approach - A review

NASA Technical Reports Server (NTRS)

Mittra, R.; Ko, W. L.; Rahmat-Samii, Y.

1979-01-01

This paper presents a brief review of some recent developments on the use of the spectral-domain approach for deriving high-frequency solutions to electromagnetics scattering and radiation problems. The spectral approach is not only useful for interpreting the well-known Keller formulas based on the geometrical theory of diffraction (GTD), it can also be employed for verifying the accuracy of GTD and other asymptotic solutions and systematically improving the results when such improvements are needed. The problem of plane wave diffraction by a finite screen or a strip is presented as an example of the application of the spectral-domain approach.

Beyond Clausius-Mossotti - Wave propagation on a polarizable point lattice and the discrete dipole approximation. [electromagnetic scattering and absorption by interstellar grains

NASA Technical Reports Server (NTRS)

Draine, B. T.; Goodman, Jeremy

1993-01-01

We derive the dispersion relation for electromagnetic waves propagating on a lattice of polarizable points. From this dispersion relation we obtain a prescription for choosing dipole polarizabilities so that an infinite lattice with finite lattice spacing will mimic a continuum with dielectric constant. The discrete dipole approximation is used to calculate scattering and absorption by a finite target by replacing the target with an array of point dipoles. We compare different prescriptions for determining the dipole polarizabilities. We show that the most accurate results are obtained when the lattice dispersion relation is used to set the polarizabilities.

Technical background, chapter 3, part B

NASA Technical Reports Server (NTRS)

1975-01-01

A description is given of the physics of electromagnetic scattering from the sea and a guideline is presented to relate an observable (such as the radar cross section) to the hydrodynamics or physical properties of the sea. As specific examples of the interdisciplinary science of electromagnetics and geophysical oceanography, the physics is discussed in connection with data provided by three instruments: namely, the scatterometer, the altimeter, and the imaging radar. The data provided by each instrument are discussed in context with specular point and Bragg scattering theories. Finally, the degrading effect of extraneous sources of noise is discussed as a limiting mechanism of the accuracy of the ocean surface measurement.

Electromagnetic field enhancement and spectrum shaping through plasmonically integrated optical vortices.

PubMed

Ahn, Wonmi; Boriskina, Svetlana V; Hong, Yan; Reinhard, Björn M

2012-01-11

We introduce a new design approach for surface-enhanced Raman spectroscopy (SERS) substrates that is based on molding the optical powerflow through a sequence of coupled nanoscale optical vortices "pinned" to rationally designed plasmonic nanostructures, referred to as Vortex Nanogear Transmissions (VNTs). We fabricated VNTs composed of Au nanodiscs by electron beam lithography on quartz substrates and characterized their near- and far-field responses through combination of computational electromagnetism, and elastic and inelastic scattering spectroscopy. Pronounced dips in the far-field scattering spectra of VNTs provide experimental evidence for an efficient light trapping and circulation within the nanostructures. Furthermore, we demonstrate that VNT integration into periodic arrays of Au nanoparticles facilitates the generation of high E-field enhancements in the VNTs at multiple defined wavelengths. We show that spectrum shaping in nested VNT structures is achieved through an electromagnetic feed-mechanism driven by the coherent multiple scattering in the plasmonic arrays and that this process can be rationally controlled by tuning the array period. The ability to generate high E-field enhancements at predefined locations and frequencies makes nested VNTs interesting substrates for challenging SERS applications. © 2011 American Chemical Society

Offshell quantum electrodynamics

NASA Astrophysics Data System (ADS)

Land, Martin; Horwitz, Lawrence P.

2013-04-01

In this paper, we develop the quantum field theory of off-shell electromagnetism, and use it to calculate the Møller scattering cross-section. This calculation leads to qualitative deviations from the usual scattering cross-sections, which are, however, small effects, but may be visible at small angles near the forward direction.

Program Models A Laser Beam Focused In An Aerosol Spray

NASA Technical Reports Server (NTRS)

Barton, J. P.

1996-01-01

Monte Carlo analysis performed on packets of light. Program for Analysis of Laser Beam Focused Within Aerosol Spray (FLSPRY) developed for theoretical analysis of propagation of laser pulse optically focused within aerosol spray. Applied for example, to analyze laser ignition arrangement in which focused laser pulse used to ignite liquid aerosol fuel spray. Scattering and absorption of laser light by individual aerosol droplets evaluated by use of electromagnetic Lorenz-Mie theory. Written in FORTRAN 77 for both UNIX-based computers and DEC VAX-series computers. VAX version of program (LEW-16051). UNIX version (LEW-16065).

Effect of Diffuse Backscatter in Cassini Datasets on the Inferred Properties of Titan's surface

NASA Astrophysics Data System (ADS)

Sultan-Salem, A. K.; Tyler, G. L.

2006-12-01

Microwave (2.18 cm-λ) backscatter data for the surface of Titan obtained with the Cassini Radar instrument exhibit a significant diffuse scattering component. An empirical scattering law of the form Acos^{n}θ, with free parameters A and n, is often employed to model diffuse scattering, which may involve one or more unidentified mechanisms and processes, such as volume scattering and scattering from surface structure that is much smaller than the electromagnetic wavelength used to probe the surface. The cosine law in general is not explicit in its dependence on either the surface structure or electromagnetic parameters. Further, the cosine law often is only a poor representation of the observed diffuse scattering, as can be inferred from computation of standard goodness-of-fit measures such as the statistical significance. We fit four Cassini datasets (TA Inbound and Outbound, T3 Outbound, and T8 Inbound) with a linear combination of a cosine law and a generalized fractal-based quasi-specular scattering law (A. K. Sultan- Salem and G. L. Tyler, J. Geophys. Res., 111, E06S08, doi:10.1029/2005JE002540, 2006), in order to demonstrate how the presence of diffuse scattering increases considerably the uncertainty in surface parameters inferred from the quasi-specular component, typically the dielectric constant of the surface material and the surface root-mean-square slope. This uncertainty impacts inferences concerning the physical properties of the surfaces that display mixed scattering properties.

Plasmon enhanced Raman scattering effect for an atom near a carbon nanotube

DOE PAGES

Bondarev, I. V.

2015-01-01

Quantum electrodynamics theory of the resonance Raman scattering is developed for an atom in a close proximity to a carbon nanotube. The theory predicts a dramatic enhancement of the Raman intensity in the strong atomic coupling regime to nanotube plasmon near-fields. This resonance scattering is a manifestation of the general electromagnetic surface enhanced Raman scattering effect, and can be used in designing efficient nanotube based optical sensing substrates for single atom detection, precision spontaneous emission control, and manipulation.

Scattering from thin dielectric straps surrounding a perfectly conducting structure

NASA Technical Reports Server (NTRS)

Al-Hekail, Zeyad; Gupta, Inder J.

1989-01-01

A method to calculate the electromagnetic scattered fields from a dielectric strap wrapped around convex, conducting structure is presented. A moment method technique is used to find the current excited within the strap by the incident plane wave. Then, Uniform Geometrical Theory of Diffraction (UTD) is used to compute the fields scattered by the strap. Reasonable agreement was obtained between the computed and the measured results. The results found in this study are useful in evaluating straps as a target support structure for scattering measurements.

Study of electromagnetic wave scattering from an inhomogeneous plasma layer using Green's function volume integral equation method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soltanmoradi, Elmira; Shokri, Babak, E-mail: b-shokri@sbu.ac.ir; Laser and Plasma Research Institute, Shahid Beheshti University, G. C., Evin, Tehran 19839-63113

Gigahertz electromagnetic wave scattering from an inhomogeneous collisional plasma layer with bell-like and Epstein electron density distributions is studied by the Green's function volume integral equation method to find the reflectance, transmittance, and absorbance coefficients of this inhomogeneous plasma. Also, the effects of the frequency of the electromagnetic wave, plasma parameters, such as collision frequency, electron density, and plasma thickness, and the effects of the profile of the electron density on the electromagnetic wave scattering from this plasma slab are investigated. According to the results, when the electron density, collision frequency, and plasma thickness are increased, collisional absorbance is enhanced,more » and as a result, the absorbance bandwidth of plasma is broadened. Moreover, this broadening is more evident for plasma with bell-like electron density profile. Also, the bandwidth of the frequency and the range of pressure in which plasma behaves as a good reflector are determined in this article. According to the results, the bandwidth of the frequency is decreased for thicker plasma with bell-like profile, while it does not vary for a different plasma thickness with Epstein profile. Moreover, the range of the pressure is decreased for bell-like profile in comparison with Epstein profile. Furthermore, due to the sharp inhomogeneity of the Epstein profile, the coefficients of plasma that are uniform for plasma with bell-like profile are changed for plasma with Epstein profile, and some perturbations are seen.« less

Analysis of EM penetration into and scattering by electrically large open waveguide cavities using Gaussian beam shooting

NASA Technical Reports Server (NTRS)

Burkholder, Robert J.; Pathak, Prabhakar H.

1991-01-01

Gaussian beam (GB) representation methods are used to analyze the electromagnetic coupling into and the scattering by a large nonuniform cavity. The aperture field in the cavity is decomposed into beams using the Gabor expansion, and shooting techniques are then employed. The method is illustrated only for the two-dimensional (2-D) case. The GBs are tracked axially using the rules of beam optics which ignore any beam distortion upon reflection at the walls. The effects of beam distortion are not significant for relatively slowly varying waveguide cavities. The field scattered into the exterior by the termination within the cavity is found using a reciprocity integral formulation which requires a knowledge of the beam fields near the termination. Numerical results based on this GB approach are presented and compared with results based on an independent reference solution.

Giant pulses of the Crab Nebula pulsar as an indicator of a strong electromagnetic wave

NASA Astrophysics Data System (ADS)

Popov, M. V.; Rudnitskii, A. G.; Soglasnov, V. A.

2017-03-01

The spectra and visibility functions of giant pulses of the Crab Nebula pulsar derived from VLBI observations carried out through the "RadioAstron" project in 2015 are analyzed. Parameters of the scattering of the pulses in the interstellar medium are measured, namely, the scattering time and decorrelation bandwidth. A comparative analysis of the shapes of the spectra and visibility functions of giant pulses obtained in real observations and via modeling of their scattering is carried out. The results suggest the presence of short bursts ( dt < 30 ns) in the structure of the giant pulses at 1668 MHz, whose brightness temperatures exceed 1038 K. These pulses propagate in the pulsar magnetosphere in a strong electromagneticwave regime, leading to the generation of additional radiation perpendicular to the direction of propagation of the giant pulses. This radiation may be associated with anomalous components of the mean pulse profile observed at frequencies above 4 GHz.

ILS Localizer Performance Study : Part I. Dallas/Fort Worth Regional Airport and Model Validation - Syracuse Hancock Airport

DOT National Transportation Integrated Search

1972-07-01

The TSC electromagnetic scattering model has been used to predict the course deviation indications (CDI) at the planned Dallas Fort Worth Regional Airport. The results show that the CDI due to scattering from the modeled airport structures are within...

Scattering and extinction by spherical particles immersed in an absorbing host medium

NASA Astrophysics Data System (ADS)

Mishchenko, Michael I.; Dlugach, Janna M.

2018-05-01

Many applications of electromagnetic scattering involve particles immersed in an absorbing rather than lossless medium, thereby making the conventional scattering theory potentially inapplicable. To analyze this issue quantitatively, we employ the FORTRAN program developed recently on the basis of the first-principles electromagnetic theory to study far-field scattering by spherical particles embedded in an absorbing infinite host medium. We further examine the phenomenon of negative extinction identified recently for monodisperse spheres and uncover additional evidence in favor of its interference origin. We identify the main effects of increasing the width of the size distribution on the ensemble-averaged extinction efficiency factor and show that negative extinction can be eradicated by averaging over a very narrow size distribution. We also analyze, for the first time, the effects of absorption inside the host medium and ensemble averaging on the phase function and other elements of the Stokes scattering matrix. It is shown in particular that increasing absorption significantly suppresses the interference structure and can result in a dramatic expansion of the areas of positive polarization. Furthermore, the phase functions computed for larger effective size parameters can develop a very deep minimum at side-scattering angles bracketed by a strong diffraction peak in the forward direction and a pronounced backscattering maximum.

Numerical Solution of Light Scattered from and Transmitted through a Rough Dielectric Surface with Applications to Periodic Roughness and Isolated Structures

NASA Technical Reports Server (NTRS)

Sun, Wenbo; Videnn, Gorden; Lin, Bing; Hu, Yongxiang

2007-01-01

Light scattering and transmission by rough surfaces are of considerable interest in a variety of applications including remote sensing and characterization of surfaces. In this work, the finite-difference time domain technique is applied to calculate the scattered and transmitted electromagnetic fields of an infinite periodic rough surface. The elements of Mueller matrix for scattered light are calculated by an integral of the near fields over a significant number of periods of the surface. The normalized Mueller matrix elements of the scattered light and the spatial distribution of the transmitted flux for a monolayer of micron-sized dielectric spheres on a silicon substrate are presented. The numerical results show that the nonzero Mueller matrix elements of the system of the monolayer of dielectric spheres on a silicon substrate have specific maxima at some scattering angles. These maxima may be used in characterization of the feature of the system. For light transmitted through the monolayer of spheres, our results show that the transmitted energy focuses around the ray passing through centers of the spheres. At other locations, the transmitted flux is very small. The technique also may be used to calculate the perturbance of the electromagnetic field due to the presence of an isolated structure on the substrate.

Electromagnetic pulse scattering by a spacecraft nearing light speed.

PubMed

Garner, Timothy J; Lakhtakia, Akhlesh; Breakall, James K; Bohren, Craig F

2017-08-01

Humans will launch spacecraft that travel at an appreciable fraction of the speed of light. Spacecraft traffic will be tracked by radar. Scattering of pulsed electromagnetic fields by an object in uniform translational motion at relativistic speed may be computed using the frame-hopping technique. Pulse scattering depends strongly on the velocity, shape, orientation, and composition of the object. The peak magnitude of the backscattered signal varies by many orders of magnitude, depending on whether the object is advancing toward or receding from the source of the interrogating signal. The peak magnitude of the backscattered signal goes to zero as the object recedes from the observer at a speed very closely approaching light speed, rendering the object invisible to the observer. The energy scattered by an object in motion may increase or decrease relative to the energy scattered by the same object at rest. Both the magnitude and sign of the change depend on the velocity of the object, as well as on its shape, orientation, and composition. In some cases, the change in total scattered energy is greatest when the object is moving transversely to the propagation direction of the interrogating signal, even though the Doppler effect is strongest when the motion is parallel or antiparallel to the propagation direction.

A new formulation of electromagnetic wave scattering using an on-surface radiation boundary condition approach

NASA Technical Reports Server (NTRS)

Kriegsmann, Gregory A.; Taflove, Allen; Umashankar, Koradar R.

1987-01-01

A new formulation of electromagnetic wave scattering by convex, two-dimensional conducting bodies is reported. This formulation, called the on-surface radiation condition (OSRC) approach, is based upon an expansion of the radiation condition applied directly on the surface of a scatterer. It is now shown that application of a suitable radiation condition directly on the surface of a convex conducting scatterer can lead to substantial simplification of the frequency-domain integral equation for the scattered field, which is reduced to just a line integral. For the transverse magnetic case, the integrand is known explicitly. For the transverse electric case, the integrand can be easily constructed by solving an ordinary differential equation around the scatterer surface contour. Examples are provided which show that OSRC yields computed near and far fields which approach the exact results for canonical shapes such as the circular cylinder, square cylinder, and strip. Electrical sizes for the examples are ka = 5 and ka = 10. The new OSRC formulation of scattering may present a useful alternative to present integral equation and uniform high-frequency approaches for convex cylinders larger than ka = 1. Structures with edges or corners can also be analyzed, although more work is needed to incorporate the physics of singular currents at these discontinuities. Convex dielectric structures can also be treated using OSRC.

On the convergence of an iterative formulation of the electromagnetic scattering from an infinite grating of thin wires

NASA Technical Reports Server (NTRS)

Brand, J. C.

1985-01-01

Contraction theory is applied to an iterative formulation of electromagnetic scattering from periodic structures and a computational method for insuring convergence is developed. A short history of spectral (or k-space) formulation is presented with an emphasis on application to periodic surfaces. The mathematical background for formulating an iterative equation is covered using straightforward single variable examples including an extension to vector spaces. To insure a convergent solution of the iterative equation, a process called the contraction corrector method is developed. Convergence properties of previously presented iterative solutions to one-dimensional problems are examined utilizing contraction theory and the general conditions for achieving a convergent solution are explored. The contraction corrector method is then applied to several scattering problems including an infinite grating of thin wires with the solution data compared to previous works.

A Least-Squares Finite Element Method for Electromagnetic Scattering Problems

NASA Technical Reports Server (NTRS)

Wu, Jie; Jiang, Bo-nan

1996-01-01

The least-squares finite element method (LSFEM) is applied to electromagnetic scattering and radar cross section (RCS) calculations. In contrast to most existing numerical approaches, in which divergence-free constraints are omitted, the LSFF-M directly incorporates two divergence equations in the discretization process. The importance of including the divergence equations is demonstrated by showing that otherwise spurious solutions with large divergence occur near the scatterers. The LSFEM is based on unstructured grids and possesses full flexibility in handling complex geometry and local refinement Moreover, the LSFEM does not require any special handling, such as upwinding, staggered grids, artificial dissipation, flux-differencing, etc. Implicit time discretization is used and the scheme is unconditionally stable. By using a matrix-free iterative method, the computational cost and memory requirement for the present scheme is competitive with other approaches. The accuracy of the LSFEM is verified by several benchmark test problems.

The Use of a Gain Monitoring System in the G0 Experiment

NASA Astrophysics Data System (ADS)

Nakos, Melissa T.

2001-11-01

The main goal of the G0 experiment is to find the contributions of the three light quark flavors to the electromagnetic properties of the nucleon by comparing the electromagnetic and neutral weak form factors, measured through the observation of parity-violating asymmetries in elastic electron-nucleon scattering. The experiment will measure the time of flight and the momentum transfer of protons (at forward scattering angles) and electrons (at backward scattering angles). The detectors used in this experiment are plastic scintillators placed in the focal plane of a magnetic spectrometer such that the momentum transfer is directly measured. A gain monitoring system has been designed to track the timing and gain of the photomultiplier tubes at the end of each scintillator. The system is made of a pulsed ultraviolet laser, pure silica fiber optic cables, and a masking system to mimic a real event.

A class of hybrid finite element methods for electromagnetics: A review

NASA Technical Reports Server (NTRS)

Volakis, J. L.; Chatterjee, A.; Gong, J.

1993-01-01

Integral equation methods have generally been the workhorse for antenna and scattering computations. In the case of antennas, they continue to be the prominent computational approach, but for scattering applications the requirement for large-scale computations has turned researchers' attention to near neighbor methods such as the finite element method, which has low O(N) storage requirements and is readily adaptable in modeling complex geometrical features and material inhomogeneities. In this paper, we review three hybrid finite element methods for simulating composite scatterers, conformal microstrip antennas, and finite periodic arrays. Specifically, we discuss the finite element method and its application to electromagnetic problems when combined with the boundary integral, absorbing boundary conditions, and artificial absorbers for terminating the mesh. Particular attention is given to large-scale simulations, methods, and solvers for achieving low memory requirements and code performance on parallel computing architectures.

Review of FD-TD numerical modeling of electromagnetic wave scattering and radar cross section

NASA Technical Reports Server (NTRS)

Taflove, Allen; Umashankar, Korada R.

1989-01-01

Applications of the finite-difference time-domain (FD-TD) method for numerical modeling of electromagnetic wave interactions with structures are reviewed, concentrating on scattering and radar cross section (RCS). A number of two- and three-dimensional examples of FD-TD modeling of scattering and penetration are provided. The objects modeled range in nature from simple geometric shapes to extremely complex aerospace and biological systems. Rigorous analytical or experimental validatons are provided for the canonical shapes, and it is shown that FD-TD predictive data for near fields and RCS are in excellent agreement with the benchmark data. It is concluded that with continuing advances in FD-TD modeling theory for target features relevant to the RCS problems and in vector and concurrent supercomputer technology, it is likely that FD-TD numerical modeling will occupy an important place in RCS technology in the 1990s and beyond.

Excited Nucleons and Hadron Structure - Proceedings of the Nstar 2000 Conference

NASA Astrophysics Data System (ADS)

Burkert, V. D.; Elouadrhiri, L.; Kelly, J. J.; Minehart, R. C.

The Table of Contents for the book is as follows: * Probing the Structure of Nucleons in the Resonance Region * Pion Photoproduction Results from MAMI * Pion Production and Compton Scattering at LEGS * Electroproduction Multipoles from ELSA * Baryon Resonance Production at Jefferson Lab at High Q2 * A Dynamical Model for the Resonant Multipoles and the Δ Structure * Relations between N and Δ Electromagnetic Form Factors * Measurement of the Recoil Polarization in the [p(ěc e ,{e^prime}ěc p ){π ^0}] Reaction at the Energy of the Δ(1232) Resonance * Electroproduction Results from CLAS * S11 (1535) Resonance Production at Jefferson Lab at High Q2 * η and η' Electro- and Photoproduction with the CEBAF Large Acceptance Spectrometer * η Production in Hadronic Interactions * Electromagnetic Production of η and η' Mesons * The Crystal Barrel Experiment at ELSA * Measurement of π-p → Neutrals Using the Crystal Ball * π+π0 and η Photoproduction at GRAAL * Partial Wave Analysis of Pion Photoproduction with Constraints from Fixed-t Dispersion Relations * N* Resonances in e+e- Collisions at BEPC * What is the Structure of the Roper Resonance? * Hybrid Baryon Signatures * Mixing Angles Determination via the Process γp → ηp * SU(6) Breaking Effects in the Nucleon Elastic Electromagnetic Form Factors * The Hypercentral Constituent Quark Model * Baryon Resonance Decays Within Constituent Quark Models * Pion Production Model - Connection between Dynamics and Quark Models * N* Investigation via Two Pion Electroproduction with the CLAS Detector at Jefferson Laboratory * Isobar Model for Studies of N* Excitation in Charged Double Pion Production by Real and Virtual Photons * Double Pion Photoproduction in the Second Resonance Region * CLAS Electroproduction of ω(783) Mesons * Electromagnetic Production of Vector Mesons at Low Energies * Polarized Target Developments for GRAAL and Prospects * Analytic Structure of a Multichannel Model * Missing Nucleon Resonances in Kaon Production with Pions and Photons * Hyperon Electroproduction with CLAS * From Bjorken to Drell-Hearn-Gerasimov Sum Rules * GDH Measurements at Mainz * Double Polarization Measurements in Inclusive Inelastic e - p Scattering * Measurement of Inclusive Spin Asymmetries and Sum Rules on 3He and the Neutron * Polarization and Out-of-Plane Responses in Pion and ETA Electroproduction * Polarization Observables in π+ Electroproduction with CLAS * Pion Electroproduction on the Nucleon and the Generalized GDH Sum Rule * Virtual Compton Scattering in the Resonance Region * What We Know about the Theoretical Foundation of Duality in Electron Scattering * Hadron Structure in Lattice QCD: Exploring the Gluon Wave Functional * N* Spectrum in Lattice QCD * Baryon Spectrum in the Large Nc Limit * Deeply Virtual Photon and Meson Electroproduction * Why N*'s are Important * Participant List

Precision Measurements of the B(E1) Strengths in 11Be

NASA Astrophysics Data System (ADS)

Kwan, E.; Wu, C. Y.; Summers, N. C.; Hackman, G.; Drake, T. E.; Andreoiu, C.; Ashley, R.; Ball, G. C.; Bender, P. C.; Boston, A. J.; Boston, H. C.; Chester, A.; Close, A.; Cline, D.; Cross, D. S.; Dunlop, R.; Finley, A.; Garnsworthy, A.; Hayes, A. B.; Laffoley, A. T.; Nano, T.; Navrátil, P.; Pearson, C. J.; Pore, J.; Starosta, K.; Thompson, I. J.; Voss, P.; Williams, S. J.; Wang, Z. M.

2014-09-01

The electromagnetic transition strength between the two bound states were measured in the one-neutron halo nucleus 11Be from Coulomb excitation on 196Pt at projectile energies of 1.727 and 2.086 MeV/nucleon at TRIUMF. A B(E1) strength of 0.102(2) e2fm2, deduced from the forward-scattering data, is consistent with previous Coulomb excitation measurements at intermediate projectile energies with a model-dependent analysis.

Detection of buried targets using a new enhanced very early time electromagnetic (VETEM) prototype system

USGS Publications Warehouse

Cui, T.J.; Chew, W.C.; Aydiner, A.A.; Wright, D.L.; Smith, D.V.

2001-01-01

In this paper, numerical simulations of a new enhanced very early time electromagnetic (VETEM) prototype system are presented, where a horizontal transmitting loop and two horizontal receiving loops are used to detect buried targets, in which three loops share the same axis and the transmitter is located at the center of receivers. In the new VETEM system, the difference of signals from two receivers is taken to eliminate strong direct-signals from the transmitter and background clutter and furthermore to obtain a better SNR for buried targets. Because strong coupling exists between the transmitter and receivers, accurate analysis of the three-loop antenna system is required, for which a loop-tree basis function method has been utilized to overcome the low-frequency breakdown problem. In the analysis of scattering problem from buried targets, a conjugate gradient (CG) method with fast Fourier transform (FFT) is applied to solve the electric field integral equation. However, the convergence of such CG-FFT algorithm is extremely slow at very low frequencies. In order to increase the convergence rate, a frequency-hopping approach has been used. Finally, the primary, coupling, reflected, and scattered magnetic fields are evaluated at receiving loops to calculate the output electric current. Numerous simulation results are given to interpret the new VETEM system. Comparing with other single-transmitter-receiver systems, the new VETEM has better SNR and ability to reduce the clutter.

Scattering from fractals

NASA Astrophysics Data System (ADS)

Hurd, Alan J.

The realization that structures in Nature often can be described by Mandelbrot's fractals has led to a revolution in many areas of physics. The interaction of waves with fractal systems has, understandably, become intensely studied since scattering is the method of choice to probe delicate fractal structures such as chainlike particle aggregates. Not all of these waves are electromagnetic. Neutron scattering, for example, is an important complementary tool to structural studies by X-ray and light scattering. Since the phenomenology of small-angle neutron scattering (SANS), as it is applied to fractal systems, is identical to that of small-angle X-ray scattering (SAXS), it falls within the scope of this paper.

Scattering and Diffraction of Electromagnetic Radiation: An Effective Probe to Material Structure

NASA Technical Reports Server (NTRS)

Xu, Yu-Lin

2016-01-01

Scattered electromagnetic waves from material bodies of different forms contain, in an intricate way, precise information on the intrinsic, geometrical and physical properties of the objects. Scattering theories, ever deepening, aim to provide dependable interpretation and prediction to the complicated interaction of electromagnetic radiation with matter. There are well-established multiple-scattering formulations based on classical electromagnetic theories. An example is the Generalized Multi-particle Mie-solution (GMM), which has recently been extended to a special version ? the GMM-PA approach, applicable to finite periodic arrays consisting of a huge number (e.g., >>106) of identical scattering centers [1]. The framework of the GMM-PA is nearly complete. When the size of the constituent unit scatterers becomes considerably small in comparison with incident wavelength, an appropriate array of such small element volumes may well be a satisfactory representation of a material entity having an arbitrary structure. X-ray diffraction is a powerful characterization tool used in a variety of scientific and technical fields, including material science. A diffraction pattern is nothing more than the spatial distribution of scattered intensity, determined by the distribution of scattering matter by way of its Fourier transform [1]. Since all linear dimensions entered into Maxwell's equations are normalized by wavelength, an analogy exists between optical and X-ray diffraction patterns. A large set of optical diffraction patterns experimentally obtained can be found in the literature [e.g., 2,3]. Theoretical results from the GMM-PA have been scrutinized using a large collection of publically accessible, experimentally obtained Fraunhofer diffraction patterns. As far as characteristic structures of the patterns are concerned, theoretical and experimental results are in uniform agreement; no exception has been found so far. Closely connected with the spatial distribution of scattered intensities are cross sections, such as for extinction, scattering, absorption, and radiation pressure, as a critical type of key quantity addressed in most theoretical and experimental studies of radiative scattering. Cross sections predicted from different scattering theories are supposed to be in general agreement. For objects of irregular shape, the GMM-PA solutions can be compared with the highly flexible Discrete Dipole Approximation (DDA) [4,5] when dividing a target to no more than 106 unit cells. Also, there are different ways to calculate the cross sections in the GMM-PA, providing an additional means to examine the accuracy of the numerical solutions and to unveil potential issues concerning the theoretical formulations and numerical aspects. To solve multiple scattering by an assembly of material volumes through classical theories such as the GMM-PA, the radiative properties of the component scatterers, the complex refractive index in particular, must be provided as input parameters. When using a PA to characterize a material body, this involves the use of an adequate theoretical tool, an effective medium theory, to connect Maxwell's phenomenogical theory with the atomistic theory of matter. In the atomic theory, one regards matter as composed of interacting particles (atoms and molecules) embedded in the vacuum [6]. However, the radiative properties of atomic-scaled particles are known to be substantially different from bulk materials. Intensive research efforts in the fields of cluster science and nanoscience attempt to bridge the gap between bulk and atom and to understand the transition from classical to quantum physics. The GMM-PA calculations, which place virtually no restriction on the component-particle size, might help to gain certain insight into the transition.

Bistatic synthetic aperture radar imaging for arbitrary flight trajectories.

PubMed

Yarman, Can Evren; Yazici, Birsen; Cheney, Margaret

2008-01-01

In this paper, we present an analytic, filtered backprojection (FBP) type inversion method for bistatic synthetic aperture radar (BISAR). We consider a BISAR system where a scene of interest is illuminated by electromagnetic waves that are transmitted, at known times, from positions along an arbitrary, but known, flight trajectory and the scattered waves are measured from positions along a different flight trajectory which is also arbitrary, but known. We assume a single-scattering model for the radar data, and we assume that the ground topography is known but not necessarily flat. We use microlocal analysis to develop the FBP-type reconstruction method. We analyze the computational complexity of the numerical implementation of the method and present numerical simulations to demonstrate its performance.

Two-dimensional simulations of stimulated Brillouin scattering in laser produced plasmas

NASA Astrophysics Data System (ADS)

Amin, M. R.; Capjack, C. E.; Frycz, P.; Rozmus, W.; Tikhonchuk, V. T.

1993-07-01

A system of electromagnetic and ion acoustic wave equations coupled via the ponderomotive force are solved numerically in a two-dimensional planar geometry. The competition between forward, side, and backward Brillouin scattering of the finite size laser beam is studied for the first time without the standard paraxial optics approximation. Simulations reveal a strong dependence of the scattered light characteristics on the geometry of the interaction region, the shape of the pump beam, and the ion acoustic wave damping. The main effects include side and forward scattering enhancement and a stimulation of collimated backward scattered radiation.

Analysis and measurement of electromagnetic scattering by pyramidal and wedge absorbers

NASA Technical Reports Server (NTRS)

Dewitt, B. T.; Burnside, Walter D.

1986-01-01

By modifying the reflection coefficients in the Uniform Geometrical Theory of Diffraction a solution that approximates the scattering from a dielectric wedge is found. This solution agrees closely with the exact solution of Rawlins which is only valid for a few minor cases. This modification is then applied to the corner diffraction coefficient and combined with an equivalent current and geometrical optics solutions to model scattering from pyramid and wedge absorbers. Measured results from 12 inch pyramid absorbers from 2 to 18 GHz are compared to calculations assuming the returns add incoherently and assuming the returns add coherently. The measured results tend to be between the two curves. Measured results from the 8 inch wedge absorber are also compared to calculations with the return being dominated by the wedge diffraction. The procedures for measuring and specifying absorber performance are discussed and calibration equations are derived to calculate a reflection coefficient or a reflectivity using a reference sphere. Shaping changes to the present absorber designs are introduced to improve performance based on both high and low frequency analysis. Some prototypes were built and tested.

Scattering characteristics of electromagnetic waves in time and space inhomogeneous weakly ionized dusty plasma sheath

NASA Astrophysics Data System (ADS)

Guo, Li-xin; Chen, Wei; Li, Jiang-ting; Ren, Yi; Liu, Song-hua

2018-05-01

The dielectric coefficient of a weakly ionised dusty plasma is used to establish a three-dimensional time and space inhomogeneous dusty plasma sheath. The effects of scattering on electromagnetic (EM) waves in this dusty plasma sheath are investigated using the auxiliary differential equation finite-difference time-domain method. Backward radar cross-sectional values of various parameters, including the dust particle radius, charging frequency of dust particles, dust particle concentration, effective collision frequency, rate of the electron density variation with time, angle of EM wave incidence, and plasma frequency, are analysed within the time and space inhomogeneous plasma sheath. The results show the noticeable effects of dusty plasma parameters on EM waves.

Scattering from Artificial Piezoelectriclike Meta-Atoms and Molecules

NASA Astrophysics Data System (ADS)

Goltcman, Leonid; Hadad, Yakir

2018-01-01

Inspired by natural piezoelectricity, we introduce hybrid-wave electromechanical meta-atoms and metamolecules that consist of coupled electrical and mechanical oscillators with similar resonance frequencies. We explore the linearized electromechanical scattering process and demonstrate that by exploiting the hybrid-wave interaction one may enable functionalities that are forbidden otherwise. For example, we study a dimer metamolecule that is highly directional for electromagnetic waves, although it is electrically deep subwavelength. This unique behavior is a consequence of the fact that, while the metamolecule is electrically small, it is acoustically large. This idea opens vistas for a plethora of exciting dynamics and phenomena in electromagnetics and acoustics, with implications for miniaturized sensors, superresolution imaging, compact nonreciprocal antennas, and more.

Direct time integration of Maxwell's equations in linear dispersive media with absorption for scattering and propagation of femtosecond electromagnetic pulses

NASA Technical Reports Server (NTRS)

Joseph, Rose M.; Hagness, Susan C.; Taflove, Allen

1991-01-01

The initial results for femtosecond pulse propagation and scattering interactions for a Lorentz medium obtained by a direct time integration of Maxwell's equations are reported. The computational approach provides reflection coefficients accurate to better than 6 parts in 10,000 over the frequency range of dc to 3 x 10 to the 16th Hz for a single 0.2-fs Gaussian pulse incident upon a Lorentz-medium half-space. New results for Sommerfeld and Brillouin precursors are shown and compared with previous analyses. The present approach is robust and permits 2D and 3D electromagnetic pulse propagation directly from the full-vector Maxwell's equations.

X-ray EM simulation tool for ptychography dataset construction

NASA Astrophysics Data System (ADS)

Stoevelaar, L. Pjotr; Gerini, Giampiero

2018-03-01

In this paper, we present an electromagnetic full-wave modeling framework, as a support EM tool providing data sets for X-ray ptychographic imaging. Modeling the entire scattering problem with Finite Element Method (FEM) tools is, in fact, a prohibitive task, because of the large area illuminated by the beam (due to the poor focusing power at these wavelengths) and the very small features to be imaged. To overcome this problem, the spectrum of the illumination beam is decomposed into a discrete set of plane waves. This allows reducing the electromagnetic modeling volume to the one enclosing the area to be imaged. The total scattered field is reconstructed by superimposing the solutions for each plane wave illumination.

Network representations of angular regions for electromagnetic scattering

PubMed Central

2017-01-01

Network modeling in electromagnetics is an effective technique in treating scattering problems by canonical and complex structures. Geometries constituted of angular regions (wedges) together with planar layers can now be approached with the Generalized Wiener-Hopf Technique supported by network representation in spectral domain. Even if the network representations in spectral planes are of great importance by themselves, the aim of this paper is to present a theoretical base and a general procedure for the formulation of complex scattering problems using network representation for the Generalized Wiener Hopf Technique starting basically from the wave equation. In particular while the spectral network representations are relatively well known for planar layers, the network modelling for an angular region requires a new theory that will be developed in this paper. With this theory we complete the formulation of a network methodology whose effectiveness is demonstrated by the application to a complex scattering problem with practical solutions given in terms of GTD/UTD diffraction coefficients and total far fields for engineering applications. The methodology can be applied to other physics fields. PMID:28817573

Polarimetric Signatures of Sea Ice. Part 1; Theoretical Model

NASA Technical Reports Server (NTRS)

Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Drinkwater, M. R.

1995-01-01

Physical, structural, and electromagnetic properties and interrelating processes in sea ice are used to develop a composite model for polarimetric backscattering signatures of sea ice. Physical properties of sea ice constituents such as ice, brine, air, and salt are presented in terms of their effects on electromagnetic wave interactions. Sea ice structure and geometry of scatterers are related to wave propagation, attenuation, and scattering. Temperature and salinity, which are determining factors for the thermodynamic phase distribution in sea ice, are consistently used to derive both effective permittivities and polarimetric scattering coefficients. Polarimetric signatures of sea ice depend on crystal sizes and brine volumes, which are affected by ice growth rates. Desalination by brine expulsion, drainage, or other mechanisms modifies wave penetration and scattering. Sea ice signatures are further complicated by surface conditions such as rough interfaces, hummocks, snow cover, brine skim, or slush layer. Based on the same set of geophysical parameters characterizing sea ice, a composite model is developed to calculate effective permittivities and backscattering covariance matrices at microwave frequencies for interpretation of sea ice polarimetric signatures.

Calculated shape dependence of electromagnetic field in tip-enhanced Raman scattering by using a monopole antenna model.

PubMed

Kitahama, Yasutaka; Itoh, Tamitake; Suzuki, Toshiaki

2018-05-15

To evaluate the shape of an Ag tip with regard to tip-enhanced Raman scattering (TERS) signal, the enhanced electromagnetic (EM) field and scattering spectrum, arising from surface plasmon resonance at the apex of the tip, were calculated using a finite-difference time domain (FDTD) method. In the calculated forward scattering spectra from the smooth Ag tip, the band appeared within the visible region, similar to the experimental results and calculation for a corrugated Ag cone. In the FDTD calculation of TERS, the Ag tip acting as a monopole antenna was adopted by insertion of a perfect electric conductor between the root of the tip and a top boundary surface of the calculation space. As a result, the EM field was only enhanced at the apex. The shape dependence i.e. the EM field calculated at the apex with various curvatures on the different tapered tips, obtained using the monopole antenna model, was different from that simulated using a conventional dipole antenna model. Copyright © 2018 Elsevier B.V. All rights reserved.

Electromagnetic scattering of large structures in layered earths using integral equations

NASA Astrophysics Data System (ADS)

Xiong, Zonghou; Tripp, Alan C.

1995-07-01

An electromagnetic scattering algorithm for large conductivity structures in stratified media has been developed and is based on the method of system iteration and spatial symmetry reduction using volume electric integral equations. The method of system iteration divides a structure into many substructures and solves the resulting matrix equation using a block iterative method. The block submatrices usually need to be stored on disk in order to save computer core memory. However, this requires a large disk for large structures. If the body is discretized into equal-size cells it is possible to use the spatial symmetry relations of the Green's functions to regenerate the scattering impedance matrix in each iteration, thus avoiding expensive disk storage. Numerical tests show that the system iteration converges much faster than the conventional point-wise Gauss-Seidel iterative method. The numbers of cells do not significantly affect the rate of convergency. Thus the algorithm effectively reduces the solution of the scattering problem to an order of O(N2), instead of O(N3) as with direct solvers.

Scattering of an electromagnetic light wave from a quasi-homogeneous medium with semisoft boundary

NASA Astrophysics Data System (ADS)

Zhou, Jianyang; Zhao, Daomu

2016-08-01

Based on the first-order Born approximation, the scattering of an electromagnetic plane wave from a relatively more realistic random medium, a quasi-homogeneous medium with semisoft boundary, has been investigated. The analytic expressions for the spectral density, the spectral degree of coherence and the spectral degree of polarization have been derived, and the effects of the characteristics of the medium and the polarization of the incident light wave on the far-zone scattered field are determined. The numerical simulations indicate that, with the increasing of the edge softness M of the medium, the spectral density presents a pattern with interference fringes, and the number, position and width of interference fringes can be modified by the parameter. It is also found that there is an obvious value saltation in the coherence profile. Besides, unlike the intensity and the coherence are significantly affected by the properties of the medium, the polarization of the scattered field is irrelevant to them due to the quasi-homogeneity and isotropy of the medium, and it is only connected with the polarization of the incident light.

Mathematical Model Taking into Account Nonlocal Effects of Plasmonic Structures on the Basis of the Discrete Source Method

NASA Astrophysics Data System (ADS)

Eremin, Yu. A.; Sveshnikov, A. G.

2018-04-01

The discrete source method is used to develop and implement a mathematical model for solving the problem of scattering electromagnetic waves by a three-dimensional plasmonic scatterer with nonlocal effects taken into account. Numerical results are presented whereby the features of the scattering properties of plasmonic particles with allowance for nonlocal effects are demonstrated depending on the direction and polarization of the incident wave.

Scattering of Electromagnetic Radiation by ITO Nanoparticles with Various Doping Levels

NASA Astrophysics Data System (ADS)

Bugaev, A. S.; Astapenko, V. A.; Manuilovich, E. S.; Sakhno, S. V.; Khramov, E. S.; Yakovets, A. V.

2018-02-01

The process of scattering of radiation by indium‒tin oxide (ITO) nanoparticles is theoretically studied at various degrees of doping and for different radii of nanoparticles. Qualitative conclusions are made about the character of the dependence of the scattering cross section on the frequency with variation of the particle size and the percentage content of tin. The prospects of using ITO nanoparticles as an active substance in optical sensors are estimated.

Electromagnetic properties of ice coated surfaces

NASA Technical Reports Server (NTRS)

Dominek, A.; Walton, E.; Wang, N.; Beard, L.

1989-01-01

The electromagnetic scattering from ice coated structures is examined. The influence of ice is shown from a measurement standpoint and related to a simple analytical model. A hardware system for the realistic measurement of ice coated structures is also being developed to use in an existing NASA Lewis icing tunnel. Presently, initial measurements have been performed with a simulated tunnel to aid in the development.

Fourth workshop on Experiments and Detectors for a Relativistic Heavy Ion Collider

NASA Technical Reports Server (NTRS)

Fatyga, M. (Editor); Moskowitz, B. (Editor)

1992-01-01

We present a description of an experiment which can be used to search for effects of strong electromagnetic fields on the production of e(sup +) e(sup -) pairs in the elastic scattering of two heavy ions at the Relativistic Heavy Ion Collider (RHIC). A very brief discussion of other possible studies of electromagnetic phenomena at RHIC is also presented.

Numerical simulation of electromagnetic waves in Schwarzschild space-time by finite difference time domain method and Green function method

NASA Astrophysics Data System (ADS)

Jia, Shouqing; La, Dongsheng; Ma, Xuelian

2018-04-01

The finite difference time domain (FDTD) algorithm and Green function algorithm are implemented into the numerical simulation of electromagnetic waves in Schwarzschild space-time. FDTD method in curved space-time is developed by filling the flat space-time with an equivalent medium. Green function in curved space-time is obtained by solving transport equations. Simulation results validate both the FDTD code and Green function code. The methods developed in this paper offer a tool to solve electromagnetic scattering problems.

Organo Luminescent semiconductor nanocrystal probes for biological applications and process for making and using such probes

DOEpatents

Weiss, Shimon; Bruchez, Jr., Marcel; Alivisatos, Paul

1999-01-01

A luminescent semiconductor nanocrystal compound is described which is capable of linking to an affinity molecule. The compound comprises (1) a semiconductor nanocrystal capable of emitting electromagnetic radiation (luminescing) in a narrow wavelength band and/or absorbing energy, and/or scattering or diffracting electromagnetic radiation--when excited by an electromagnetic radiation source (of narrow or broad bandwidth) or a particle beam; and (2) at least one linking agent, having a first portion linked to the semiconductor nanocrystal and a second portion capable of linking to an affinity molecule. The luminescent semiconductor nanocrystal compound is linked to an affinity molecule to form an organo luminescent semiconductor nanocrystal probe capable of bonding with a detectable substance in a material being analyzed, and capable of emitting electromagnetic radiation in a narrow wavelength band and/or absorbing, scattering, or diffracting energy when excited by an electromagnetic radiation source (of narrow or broad bandwidth) or a particle beam. The probe is stable to repeated exposure to light in the presence of oxygen and/or other radicals. Further described is a process for making the luminescent semiconductor nanocrystal compound and for making the organo luminescent semiconductor nanocrystal probe comprising the luminescent semiconductor nanocrystal compound linked to an affinity molecule capable of bonding to a detectable substance. A process is also described for using the probe to determine the presence of a detectable substance in a material.

Reflection and Transmission of Plane Electromagnetic Waves by a Geologic Layer.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aldridge, David F.

Electric field and magnetic field reflection and transmission responses generated by a plane wave normally incident onto a finite - thickness geologic layer are mathematically derived and numerically evaluated. A thin layer with enhanced electric current conductivity and/or magnetic permeability is a reasonable geophysical representation of a hydraulic fracture inject ed with a high - contrast proppant pack. Both theory and numerics indicate that backward - and forward - scattered electromagnetic wavefields are potentially observable in a field experiment, despite the extreme thinness of a fracture compared to a typical low - frequency electromagnetic wavelength. The First Born Approximation (FBA)more » representation of layer scattering, significant for inversion studies, is shown to be accurate for a thin layer with mild medium parameter (i.e., conductivity, permeability, and per mittivity) contrasts with the surrounding homogeneous wholespace. However, FBA scattering theory breaks down for thick layers and strong parameter contrasts. ACKNOWLEDGEMENTS Sandia National Laboratories is a multi - mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE - AC04 - 94AL85000. This research is conducted under the auspices of CRADA (Cooperative Research and Development Agreement) SC11/01780.00 between Carbo Ceramics Inc. and Sandia National Laboratories. The author acknowledges former Carbo R&D Vic e - President Mr. Chad Cannan and former SNL Geophysics Department manage r Ms. Amy Halloran for their interest i n and support of this work. Technical discussions with Project Manager and Principal Investigator Dr. Chester J. Weiss of the SNL Geophysics Department greatly benefited this work. Dr. Lewis C. Bartel, formerly with S NL and presently a consultant to Carbo Ceramics, provided many useful and intuitive insights, and is acknowledged as the originator of the concept underpinning a recent patent grant (Aldridge and Bartel, 2016) involving electromagnetic wave scattering.« less

Free Space Analysis of the Scattered Electromagnetic Fields as a Dipole Approaches a Leaky Coaxial Cable.

DTIC Science & Technology

1981-12-01

Transactions on Antennas and Propagation, Vol AP-4: 288-93 (July 1956). 16. Von Hippel , Arthur R. Dielectric Materials and Applications. New York: John Wiley...KA=1,10 AT-KA/10.0-0.05 P-11-ATAN (ANT/CD! ST I EOIST-SORT(A%T92.0,COIST#*Z.0) M(-SQ2T(dETAI*,2Z.0-dFTA*#2.0) ARC ISHO*EDIST CALL MODBES(ARG1,KL) ERIC

Multi-modality analysis of glucose aqueous solution using photoacoustic and dielectric spectroscopy for non-invasive glucose monitoring

NASA Astrophysics Data System (ADS)

Tajima, Takuro; Tanaka, Yujiro; Nakamura, Masahito; Seyama, Michiko

2017-03-01

Quantitative analysis of glucose using conventional optical spectroscopy suffers from a lack of repeatability due to high optical scattering in skin tissue. Here we present a multi-modality analysis of glucose aqueous solution using photoacoustic spectroscopy (PAS) and broadband dielectric spectroscopy (BDS). These techniques involve the direct detection of the acoustic and electromagnetic waves propagating through or reflecting from tissue without their being scattered. They therefore have potential for better tolerance to the variation of scattering. For PAS, to differentiate signals induced by water absorption, we select another laser wavelength (1.38 μm) that exhibits the same absorbance for water at 1.61 μm. Furthermore, one of the two photoacoustic signals is used to normalize the variations of acoustic properties in differential signal. Measured results for glucose solutions (0-2 g/dL) showed that the differential signal has a sensitivity of 1.61%/g·dL-1 and a detection limit of 120 mg/dL. We also tested glucose detection with BDS (500 MHz to 50 GHz) by detecting glucose hydration bonding at around 10-20 GHz. Using a partial least square analysis and first derivation on broadband spectra, we obtained an RMS error 19 mg/dL and a detection limit of 59 mg/dL. Using both the low-scattering ultrasonic and microwave detection techniques, we successfully captured the glucose footprint in the physiological range.

Full-wave Characterization of Rough Terrain Surface Effects for Forward-looking Radar Applications: A Scattering and Imaging Study from the Electromagnetic Perspective

DTIC Science & Technology

2011-09-01

and Imaging Framework First, the parallelized 3-D FDTD algorithm is applied to simulate composite scattering from targets in a rough ground...solver as pertinent to forward-looking radar sensing , the effects of surface clutter on multistatic target imaging are illustrated with large-scale...Full-wave Characterization of Rough Terrain Surface Effects for Forward-looking Radar Applications: A Scattering and Imaging Study from the

Analytical study of the effects of clouds on the light produced by lightning

NASA Technical Reports Server (NTRS)

Phanord, Dieudonne D.

1990-01-01

Researchers consider the scattering of visible and infrared light due to lightning by cubic, cylindrical and spherical clouds. The researchers extend to cloud physics the work by Twersky for single and multiple scattering of electromagnetic waves. They solve the interior problem separately to obtain the bulk parameters for the scatterer equivalent to the ensemble of spherical droplets. With the interior solution or the equivalent medium approach, the multiple scattering problem is reduced to that of a single scatterer in isolation. Hence, the computing methods of Wiscombe or Bohren specialized to Mie scattering with the possibility for absorption were used to generate numerical results in short computer time.

Multiple scattering in planetary regoliths using first-order incoherent interactions

NASA Astrophysics Data System (ADS)

Muinonen, Karri; Markkanen, Johannes; Väisänen, Timo; Penttilä, Antti

2017-10-01

We consider scattering of light by a planetary regolith modeled using discrete random media of spherical particles. The size of the random medium can range from microscopic sizes of a few wavelengths to macroscopic sizes approaching infinity. The size of the particles is assumed to be of the order of the wavelength. We extend the numerical Monte Carlo method of radiative transfer and coherent backscattering (RT-CB) to the case of dense packing of particles. We adopt the ensemble-averaged first-order incoherent extinction, scattering, and absorption characteristics of a volume element of particles as input for the RT-CB. The volume element must be larger than the wavelength but smaller than the mean free path length of incoherent extinction. In the radiative transfer part, at each absorption and scattering process, we account for absorption with the help of the single-scattering albedo and peel off the Stokes parameters of radiation emerging from the medium in predefined scattering angles. We then generate a new scattering direction using the joint probability density for the local polar and azimuthal scattering angles. In the coherent backscattering part, we utilize amplitude scattering matrices along the radiative-transfer path and the reciprocal path, and utilize the reciprocity of electromagnetic waves to verify the computation. We illustrate the incoherent volume-element scattering characteristics and compare the dense-medium RT-CB to asymptotically exact results computed using the Superposition T-matrix method (STMM). We show that the dense-medium RT-CB compares favorably to the STMM results for the current cases of sparse and dense discrete random media studied. The novel method can be applied in modeling light scattering by the surfaces of asteroids and other airless solar system objects, including UV-Vis-NIR spectroscopy, photometry, polarimetry, and radar scattering problems.Acknowledgments. Research supported by European Research Council with Advanced Grant No. 320773 SAEMPL, Scattering and Absorption of ElectroMagnetic waves in ParticuLate media. Computational resources provided by CSC - IT Centre for Science Ltd, Finland.

Numerical electromagnetic frequency domain analysis with discrete exterior calculus

NASA Astrophysics Data System (ADS)

Chen, Shu C.; Chew, Weng Cho

2017-12-01

In this paper, we perform a numerical analysis in frequency domain for various electromagnetic problems based on discrete exterior calculus (DEC) with an arbitrary 2-D triangular or 3-D tetrahedral mesh. We formulate the governing equations in terms of DEC for 3-D and 2-D inhomogeneous structures, and also show that the charge continuity relation is naturally satisfied. Then we introduce a general construction for signed dual volume to incorporate material information and take into account the case when circumcenters fall outside triangles or tetrahedrons, which may lead to negative dual volume without Delaunay triangulation. Then we examine the boundary terms induced by the dual mesh and provide a systematical treatment of various boundary conditions, including perfect magnetic conductor (PMC), perfect electric conductor (PEC), Dirichlet, periodic, and absorbing boundary conditions (ABC) within this method. An excellent agreement is achieved through the numerical calculation of several problems, including homogeneous waveguides, microstructured fibers, photonic crystals, scattering by a 2-D PEC, and resonant cavities.

The Scattering of Partially Coherent Electromagnetic Beam Illumination from Statistically Rough Surfaces

DTIC Science & Technology

2014-06-19

scattering research performed by the radio - frequency /microwave and visible/near-infrared communities for synthetic aperture radar and remote...Rough Surfaces with Arbitrary Slope and Frequency ,” IEEE Trans. Antennas Propag. 28, 11 - 21 (1980). 76. E. Bahar, “Full-Wave Solutions for the...equations ..................................................................................... 11 2.2.1 Electric-field integral equations

Lectures on Quantum Mechanics

NASA Astrophysics Data System (ADS)

Weinberg, Steven

2015-09-01

Preface; Notation; 1. Historical introduction; 2. Particle states in a central potential; 3. General principles of quantum mechanics; 4. Spin; 5. Approximations for energy eigenstates; 6. Approximations for time-dependent problems; 7. Potential scattering; 8. General scattering theory; 9. The canonical formalism; 10. Charged particles in electromagnetic fields; 11. The quantum theory of radiation; 12. Entanglement; Author index; Subject index.

Advancements in Electromagnetic Wave Backscattering Simulations: Applications in Active Lidar Remote Sensing Involving Aerosols

NASA Astrophysics Data System (ADS)

Bi, L.

2016-12-01

Atmospheric remote sensing based on the Lidar technique fundamentally relies on knowledge of the backscattering of light by particulate matters in the atmosphere. This talk starts with a review of the current capabilities of electromagnetic wave scattering simulations to determine the backscattering optical properties of irregular particles, such as the backscatterer and depolarization ratio. This will be followed by a discussion of possible pitfalls in the relevant simulations. The talk will then be concluded with reports on the latest advancements in computational techniques. In addition, we summarize the laws of the backscattering optical properties of aerosols with respect to particle geometries, particle sizes, and mixing rules. These advancements will be applied to the analysis of the Lidar observation data to reveal the state and possible microphysical processes of various aerosols.

MUSIC electromagnetic imaging with enhanced resolution for small inclusions

NASA Astrophysics Data System (ADS)

Chen, Xudong; Zhong, Yu

2009-01-01

This paper investigates the influence of the test dipole on the resolution of the multiple signal classification (MUSIC) imaging method applied to the electromagnetic inverse scattering problem of determining the locations of a collection of small objects embedded in a known background medium. Based on the analysis of the induced electric dipoles in eigenstates, an algorithm is proposed to determine the test dipole that generates a pseudo-spectrum with enhanced resolution. The amplitudes in three directions of the optimal test dipole are not necessarily in phase, i.e., the optimal test dipole may not correspond to a physical direction in the real three-dimensional space. In addition, the proposed test-dipole-searching algorithm is able to deal with some special scenarios, due to the shapes and materials of objects, to which the standard MUSIC does not apply.

A new MUSIC electromagnetic imaging method with enhanced resolution for small inclusions

NASA Astrophysics Data System (ADS)

Zhong, Yu; Chen, Xudong

2008-11-01

This paper investigates the influence of test dipole on the resolution of the multiple signal classification (MUSIC) imaging method applied to the electromagnetic inverse scattering problem of determining the locations of a collection of small objects embedded in a known background medium. Based on the analysis of the induced electric dipoles in eigenstates, an algorithm is proposed to determine the test dipole that generates a pseudo-spectrum with enhanced resolution. The amplitudes in three directions of the optimal test dipole are not necessarily in phase, i.e., the optimal test dipole may not correspond to a physical direction in the real three-dimensional space. In addition, the proposed test-dipole-searching algorithm is able to deal with some special scenarios, due to the shapes and materials of objects, to which the standard MUSIC doesn't apply.

Numerical time-domain electromagnetics based on finite-difference and convolution

NASA Astrophysics Data System (ADS)

Lin, Yuanqu

Time-domain methods posses a number of advantages over their frequency-domain counterparts for the solution of wideband, nonlinear, and time varying electromagnetic scattering and radiation phenomenon. Time domain integral equation (TDIE)-based methods, which incorporate the beneficial properties of integral equation method, are thus well suited for solving broadband scattering problems for homogeneous scatterers. Widespread adoption of TDIE solvers has been retarded relative to other techniques by their inefficiency, inaccuracy and instability. Moreover, two-dimensional (2D) problems are especially problematic, because 2D Green's functions have infinite temporal support, exacerbating these difficulties. This thesis proposes a finite difference delay modeling (FDDM) scheme for the solution of the integral equations of 2D transient electromagnetic scattering problems. The method discretizes the integral equations temporally using first- and second-order finite differences to map Laplace-domain equations into the Z domain before transforming to the discrete time domain. The resulting procedure is unconditionally stable because of the nature of the Laplace- to Z-domain mapping. The first FDDM method developed in this thesis uses second-order Lagrange basis functions with Galerkin's method for spatial discretization. The second application of the FDDM method discretizes the space using a locally-corrected Nystrom method, which accelerates the precomputation phase and achieves high order accuracy. The Fast Fourier Transform (FFT) is applied to accelerate the marching-on-time process in both methods. While FDDM methods demonstrate impressive accuracy and stability in solving wideband scattering problems for homogeneous scatterers, they still have limitations in analyzing interactions between several inhomogenous scatterers. Therefore, this thesis devises a multi-region finite-difference time-domain (MR-FDTD) scheme based on domain-optimal Green's functions for solving sparsely-populated problems. The scheme uses a discrete Green's function (DGF) on the FDTD lattice to truncate the local subregions, and thus reduces reflection error on the local boundary. A continuous Green's function (CGF) is implemented to pass the influence of external fields into each FDTD region which mitigates the numerical dispersion and anisotropy of standard FDTD. Numerical results will illustrate the accuracy and stability of the proposed techniques.

Wave-Based Algorithms and Bounds for Target Support Estimation

DTIC Science & Technology

2015-05-15

vector electromagnetic formalism in [5]. This theory leads to three main variants of the optical theorem detector, in particular, three alternative...further expands the applicability for transient pulse change detection of ar- bitrary nonlinear-media and time-varying targets [9]. This report... electromagnetic methods a new methodology to estimate the minimum convex source region and the (possibly nonconvex) support of a scattering target from knowledge of

Conference Proceedings: 7th Annual Review of Progress in Applied Computational Electromagnetics at the Naval Postgraduate School, Monterey, California, March 18-22, 1991

DTIC Science & Technology

1991-03-01

34Volume integral Equations and Conjugate Gradient Methods in Electromagnetic Non destructive Evaluation’ by Dr. Harold P.. Sabbagh, Sabbagh Associates...8217 Experimental Demonstrations far teaching Electroamgnetic Folods and Energy’ M. Zathn, J. Mectrer...8217-....................................... . ...................................................... 329 ’PoalarimetrIc Scattering and Control at Radar Crass Section of Chirat Targets at Simple

Geometrical-optics code for computing the optical properties of large dielectric spheres.

PubMed

Zhou, Xiaobing; Li, Shusun; Stamnes, Knut

2003-07-20

Absorption of electromagnetic radiation by absorptive dielectric spheres such as snow grains in the near-infrared part of the solar spectrum cannot be neglected when radiative properties of snow are computed. Thus a new, to our knowledge, geometrical-optics code is developed to compute scattering and absorption cross sections of large dielectric particles of arbitrary complex refractive index. The number of internal reflections and transmissions are truncated on the basis of the ratio of the irradiance incident at the nth interface to the irradiance incident at the first interface for a specific optical ray. Thus the truncation number is a function of the angle of incidence. Phase functions for both near- and far-field absorption and scattering of electromagnetic radiation are calculated directly at any desired scattering angle by using a hybrid algorithm based on the bisection and Newton-Raphson methods. With these methods a large sphere's absorption and scattering properties of light can be calculated for any wavelength from the ultraviolet to the microwave regions. Assuming that large snow meltclusters (1-cm order), observed ubiquitously in the snow cover during summer, can be characterized as spheres, one may compute absorption and scattering efficiencies and the scattering phase function on the basis of this geometrical-optics method. A geometrical-optics method for sphere (GOMsphere) code is developed and tested against Wiscombe's Mie scattering code (MIE0) and a Monte Carlo code for a range of size parameters. GOMsphere can be combined with MIE0 to calculate the single-scattering properties of dielectric spheres of any size.

Cotton fiber quality characterization with light scattering and fourier transform infrared techniques.

PubMed

Thomasson, J A; Manickavasagam, S; Mengüç, M P

2009-03-01

Fiber quality measurement is critical to assessing the value of a bale of cotton for various textile purposes. An instrument that could measure numerous cotton quality properties by optical means could be made simpler and faster than current fiber quality measurement instruments, and it might be more amenable to on-line measurement at processing facilities. To that end, a laser system was used to investigate cotton fiber samples with respect to electromagnetic scattering at various wavelengths, polarization angles, and scattering angles. A Fourier transform infrared (FT-IR) instrument was also used to investigate the transmission of electromagnetic energy at various mid-infrared wavelengths. Cotton samples were selected to represent a wide range of micronaire values. Varying the wavelength of the laser at a fixed polarization resulted in little variation in scattered light among the cotton samples. However, varying the polarization at a fixed wavelength produced notable variation, indicating that polarization might be used to differentiate among cotton samples with respect to certain fiber properties. The FT-IR data in the 12 to 22 microm range produced relatively large differences in the amount of scattered light among all samples, and FT-IR data at certain combinations of fixed wavelengths were highly linearly related to certain measures of cotton quality including micronaire.

Asymptotic quantum elastic generalized Lorenz Mie theory

NASA Astrophysics Data System (ADS)

Gouesbet, G.

2006-10-01

The (electromagnetic) generalized Lorenz-Mie theory describes the interaction between an electromagnetic arbitrary shaped beam and a homogeneous sphere. It is a generalization of the Lorenz-Mie theory which deals with the simpler case of a plane-wave illumination. In a recent paper, we established that, if we restrict ourselves to the study of cross-sections, both for elastic and inelastic scatterings, a macroscopic sphere in Lorenz-Mie theory is formally equivalent to a quantum-like radial potential. To generalize this result, a prerequisite is to possess an asymptotic quantum generalized Lorenz-Mie theory expressing cross-sections in the case of a quantum radial potential interacting with a sub-class of quantum arbitrary wave-packets. Such a theory, restricted however to elastic scattering, is presented in this paper.

Radiation, Scattering and Guidance of Electromagnetic Fields by Arbitrarily Shaped Structures Embedded in Layered Media

DTIC Science & Technology

1993-03-31

34h(d by tIo)1 i Th1at 1 501i k, p S ~and by m aking use of. the dlivt’rgen4’’ Iievoreni . A.. .;m’t wlitu A-, 1 1 ~jA,-,k; p k u n,/ where V = z x ui...8217Conftrence anti Lxposition. (Toronto, Canada), pp. 660-66.5, Sept. 1983. [36] S. U . Hwu, D. R. Wilton, and S. M . Rao. "’Electromagnetic scattering and...o P , -rlI•(kp-,d O)ý~. M ~ ’, u O ’ (4:3) where jo and o are the radial and azimuthal unit vectors evaluated at (0 ,. ’o), and l• = kkP, with k

Resonant Spectra of Malignant Breast Cancer Tumors Using the Three-Dimensional Electromagnetic Fast Multipole Model. Part 1

NASA Technical Reports Server (NTRS)

El-Shenawee, Magda

2003-01-01

An intensive numerical study for the resonance scattering of malignant breast cancer tumors is presented. The rigorous three-dimensional electromagnetic model, based on the equivalence theorem, is used to obtain the induced electric and magnetic currents on the breast and tumor surfaces. The results show that a non-spherical malignant tumor can be characterized based its spectra regardless of its orientation, the incident polarization, or the incident or scattered directions. The tumor's spectra depend solely on its physical characteristics (i.e., the shape and the electrical properties), however, their locations are not functions of its burial depth. This work provides a useful guidance to select the appropriate frequency range for the tumor's size.

Benchmarks of simple, generic, shaped plates for validation of low-frequency electromagnetic computational codes

NASA Technical Reports Server (NTRS)

Deshpande, M. D.; Cockrell, C. R.; Beck, F. B.; Nguyen, T. X.

1993-01-01

The validation of low-frequency measurements and electromagnetic (EM) scattering computations for several simple, generic shapes, such as an equilateral-triangular plate, an equilateral-triangular plate with a concentric equilateral-triangular hole, and diamond- and hexagonal-shaped plates, is discussed. The plates were constructed from a thin aluminum sheet with a thickness of 0.08 cm. EM scattering by the planar plates was measured in the experimental test range (ETR) facility of NASA Langley Research Center. The dimensions of the plates were selected such that, over the frequency range of interest, the dimensions were in the range of lambda0 to 3(lambda0). In addition, the triangular plate with a triangular hole was selected to study internal-hole resonances.

The Impact of Microstructure on an Accurate Snow Scattering Parameterization at Microwave Wavelengths

NASA Astrophysics Data System (ADS)

Honeyager, Ryan

High frequency microwave instruments are increasingly used to observe ice clouds and snow. These instruments are significantly more sensitive than conventional precipitation radar. This is ideal for analyzing ice-bearing clouds, for ice particles are tenuously distributed and have effective densities that are far less than liquid water. However, at shorter wavelengths, the electromagnetic response of ice particles is no longer solely dependent on particle mass. The shape of the ice particles also plays a significant role. Thus, in order to understand the observations of high frequency microwave radars and radiometers, it is essential to model the scattering properties of snowflakes correctly. Several research groups have proposed detailed models of snow aggregation. These particle models are coupled with computer codes that determine the particles' electromagnetic properties. However, there is a discrepancy between the particle model outputs and the requirements of the electromagnetic models. Snowflakes have countless variations in structure, but we also know that physically similar snowflakes scatter light in much the same manner. Structurally exact electromagnetic models, such as the discrete dipole approximation (DDA), require a high degree of structural resolution. Such methods are slow, spending considerable time processing redundant (i.e. useless) information. Conversely, when using techniques that incorporate too little structural information, the resultant radiative properties are not physically realistic. Then, we ask the question, what features are most important in determining scattering? This dissertation develops a general technique that can quickly parameterize the important structural aspects that determine the scattering of many diverse snowflake morphologies. A Voronoi bounding neighbor algorithm is first employed to decompose aggregates into well-defined interior and surface regions. The sensitivity of scattering to interior randomization is then examined. The loss of interior structure is found to have a negligible impact on scattering cross sections, and backscatter is lowered by approximately five percent. This establishes that detailed knowledge of interior structure is not necessary when modeling scattering behavior, and it also provides support for using an effective medium approximation to describe the interiors of snow aggregates. The Voronoi diagram-based technique enables the almost trivial determination of the effective density of this medium. A bounding neighbor algorithm is then used to establish a greatly improved approximation of scattering by equivalent spheroids. This algorithm is then used to posit a Voronoi diagram-based definition of effective density approach, which is used in concert with the T-matrix method to determine single-scattering cross sections. The resulting backscatters are found to reasonably match those of the DDA over frequencies from 10.65 to 183.31 GHz and particle sizes from a few hundred micrometers to nine millimeters in length. Integrated error in backscatter versus DDA is found to be within 25% at 94 GHz. Errors in scattering cross-sections and asymmetry parameters are likewise small. The observed cross-sectional errors are much smaller than the differences observed among different particle models. This represents a significant improvement over established techniques, and it demonstrates that the radiative properties of dense aggregate snowflakes may be adequately represented by equal-mass homogeneous spheroids. The present results can be used to supplement retrieval algorithms used by CloudSat, EarthCARE, Galileo, GPM and SWACR radars. The ability to predict the full range of scattering properties is potentially also useful for other particle regimes where a compact particle approximation is applicable.

Designing of Multiphase Fly Ash/MWCNT/PU Composite Sheet Against Electromagnetic Environmental Pollution

NASA Astrophysics Data System (ADS)

Gujral, Parth; Varshney, Swati; Dhawan, S. K.

2016-06-01

Fly ash and multiwalled carbon nanotubes (MWCNT) reinforced multiphase polyurethane (PU) composite sheets have been fabricated by using a solution casting technique. Utilization of fly ash was the prime objective in order to reduce environmental pollution and to enhance the shielding properties of PU polymer. Our study proves that fly ash particles with MWCNTs in a PU matrix leads to novel hybrid high performance electromagnetic shielding interference material. Scanning electron microscopy confirms the existence of fly ash particles along with MWCNTs in a PU matrix. This multiphase composite shows total shielding effectiveness of 35.8 dB (>99.99% attenuation) in the Ku-band (12.4-18 GHz) frequency range. This is attributed to high dielectric losses of reinforcement present in the polymers matrix. The Nicolson-Ross-Weir algorithm has been applied to calculate the electromagnetic attributes and dielectric parameters of the PU samples by using scattering parameters ( S 11, S 22, S 12, S 21). The synthesized multiphase composites were further characterized by using x-ray diffraction, Fourier transform infrared spectroscopy, and thermo gravimetric analysis.

Integral Equations in Computational Electromagnetics: Formulations, Properties and Isogeometric Analysis

NASA Astrophysics Data System (ADS)

Lovell, Amy Elizabeth

Computational electromagnetics (CEM) provides numerical methods to simulate electromagnetic waves interacting with its environment. Boundary integral equation (BIE) based methods, that solve the Maxwell's equations in the homogeneous or piecewise homogeneous medium, are both efficient and accurate, especially for scattering and radiation problems. Development and analysis electromagnetic BIEs has been a very active topic in CEM research. Indeed, there are still many open problems that need to be addressed or further studied. A short and important list includes (1) closed-form or quasi-analytical solutions to time-domain integral equations, (2) catastrophic cancellations at low frequencies, (3) ill-conditioning due to high mesh density, multi-scale discretization, and growing electrical size, and (4) lack of flexibility due to re-meshing when increasing number of forward numerical simulations are involved in the electromagnetic design process. This dissertation will address those several aspects of boundary integral equations in computational electromagnetics. The first contribution of the dissertation is to construct quasi-analytical solutions to time-dependent boundary integral equations using a direct approach. Direct inverse Fourier transform of the time-harmonic solutions is not stable due to the non-existence of the inverse Fourier transform of spherical Hankel functions. Using new addition theorems for the time-domain Green's function and dyadic Green's functions, time-domain integral equations governing transient scattering problems of spherical objects are solved directly and stably for the first time. Additional, the direct time-dependent solutions, together with the newly proposed time-domain dyadic Green's functions, can enrich the time-domain spherical multipole theory. The second contribution is to create a novel method of moments (MoM) framework to solve electromagnetic boundary integral equation on subdivision surfaces. The aim is to avoid the meshing and re-meshing stages to accelerate the design process when the geometry needs to be updated. Two schemes to construct basis functions on the subdivision surface have been explored. One is to use the div-conforming basis function, and the other one is to create a rigorous iso-geometric approach based on the subdivision basis function with better smoothness properties. This new framework provides us better accuracy, more stability and high flexibility. The third contribution is a new stable integral equation formulation to avoid catastrophic cancellations due to low-frequency breakdown or dense-mesh breakdown. Many of the conventional integral equations and their associated post-processing operations suffer from numerical catastrophic cancellations, which can lead to ill-conditioning of the linear systems or serious accuracy problems. Examples includes low-frequency breakdown and dense mesh breakdown. Another instability may come from nontrivial null spaces of involving integral operators that might be related with spurious resonance or topology breakdown. This dissertation presents several sets of new boundary integral equations and studies their analytical properties. The first proposed formulation leads to the scalar boundary integral equations where only scalar unknowns are involved. Besides the requirements of gaining more stability and better conditioning in the resulting linear systems, multi-physics simulation is another driving force for new formulations. Scalar and vector potentials (rather than electromagnetic field) based formulation have been studied for this purpose. Those new contributions focus on different stages of boundary integral equations in an almost independent manner, e.g. isogeometric analysis framework can be used to solve different boundary integral equations, and the time-dependent solutions to integral equations from different formulations can be achieved through the same methodology proposed.

A Cryogenic Target for Compton Scattering Experiments at HI γS

NASA Astrophysics Data System (ADS)

Kendellen, David; Ahmed, Mohammad; Weller, Henry; Feldman, Gerald

2015-04-01

We have designed, constructed, and tested a cryogenic target for use at the High Intensity γ-ray Source (HI γS). The target is able to liquefy helium (LHe), hydrogen (LH2), and deuterium (LD2). It precools room-temperature gas in two stages with a Gifford-McMahon cryocooler. The precooled gas condenses onto a series of copper fins and drips down to fill a 0.25 L Kapton target cell. The cryotarget will be used to measure nuclear and nucleon electromagnetic polarizabilities. The electromagnetic polarizabilities of the nucleons, α and β, will be probed by scattering a γ-ray beam on unpolarized LD2 and LH2 targets. Scattered photons will be detected by the HI γS NaI Detector Array (HINDA). We have tested the target with LHe at 3 K and are preparing for LD2 testing and production running. Work supported by US Department of Energy Contracts DE-FG02-97ER41033, DE-FG02-06ER41422, and DE-SCOO0536.

Superscaling in electron-nucleus scattering and its link to CC and NC QE neutrino-nucleus scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barbaro, M. B.; Amaro, J. E.; Caballero, J. A.

2015-05-15

The superscaling approach (SuSA) to neutrino-nucleus scattering, based on the assumed universality of the scaling function for electromagnetic and weak interactions, is reviewed. The predictions of the SuSA model for bot CC and NC differential and total cross sections are presented and compared with the MiniBooNE data. The role of scaling violations, in particular the contribution of meson exchange currents in the two-particle two-hole sector, is explored.

Bistatic 3D Electromagnetic Scattering From a Right-Angle Dihedral at Arbitrary Orientation and Position

DTIC Science & Technology

2011-03-24

compared to shooting and bouncing rays (SBR) and method of moments (MoM) predictions, as well as measured data for applicable cases. The model in this...prediction codes based on Shooting and Bouncing Rays (SBR) or Method of Moments (MoM) can be used to obtain accurate bistatic scatter- ing solutions for a...in-plane RCS pattern for dihedral. (a) For monostatic in-plane scattering, rays entering a right-angle dihedral are reflected back in the direction

PEPSI — a Monte Carlo generator for polarized leptoproduction

NASA Astrophysics Data System (ADS)

Mankiewicz, L.; Schäfer, A.; Veltri, M.

1992-09-01

We describe PEPSI (Polarized Electron Proton Scattering Interactions), a Monte Carlo program for polarized deep inelastic leptoproduction mediated by electromagnetic interaction, and explain how to use it. The code is a modification of the LEPTO 4.3 Lund Monte Carlo for unpolarized scattering. The hard virtual gamma-parton scattering is generated according to the polarization-dependent QCD cross-section of the first order in α S. PEPSI requires the standard polarization-independent JETSET routines to simulate the fragmentation into final hadrons.

Extracting the σ-term from low-energy pion-nucleon scattering

NASA Astrophysics Data System (ADS)

Ruiz de Elvira, Jacobo; Hoferichter, Martin; Kubis, Bastian; Meißner, Ulf-G.

2018-02-01

We present an extraction of the pion-nucleon (π N) scattering lengths from low-energy π N scattering, by fitting a representation based on Roy-Steiner equations to the low-energy data base. We show that the resulting values confirm the scattering-length determination from pionic atoms, and discuss the stability of the fit results regarding electromagnetic corrections and experimental normalization uncertainties in detail. Our results provide further evidence for a large π N σ-term, {σ }π N=58(5) {{MeV}}, in agreement with, albeit less precise than, the determination from pionic atoms.

Light propagation in dentin: influence of microstructure on anisotropy.

PubMed

Kienle, Alwin; Forster, Florian K; Diebolder, Rolf; Hibst, Raimund

2003-01-21

We investigated the dependence of light propagation in human dentin on its microstructure. The main scatterers in dentin are the tubules, the shape of which can be approximated as long cylinders. We calculated the scattering of electromagnetic waves by an infinitely long cylinder and applied the results in a Monte Carlo code that simulates the light propagation in a dentin slab considering multi-scattering. The theory was compared with goniometric measurements. A pronounced anisotropic scattering pattern was found experimentally and theoretically. In addition, intensity peaks were measured which are shown to be caused by light diffraction by the tubules.

Variational divergence in wave scattering theory with Kirchhoffean trial functions

NASA Technical Reports Server (NTRS)

Bird, J. F.

1986-01-01

In a recent study of variational improvement of the Kirchhoff approximation for electromagnetic scattering by rough surfaces, a key ingredient in the variational principle was found to diverge for important configurations (e.g., backscatter) if the polarization had any vertical component. The cause and a cure of this divergence are discussed here. The divergence is demonstrated to occur for arbitrary perfectly conducting scatterers and its universal characterstics are determined, by means of a general divergence criterion that is derived. A variational cure for the divergence is prescribed, and it is tested successfully on a standard scattering model.

Theory of Thomson scattering in inhomogeneous plasmas

NASA Astrophysics Data System (ADS)

Belyi, V. V.

2018-05-01

A self-consistent kinetic theory of Thomson scattering of an electromagnetic field by a nonuniform plasma is derived. We show that not only the imaginary part, but also the time and space derivatives of the real part of the dielectric susceptibility determine the amplitude and the width of the Thomson scattering spectral lines. As a result of inhomogeneity, these properties become asymmetric with respect to inversion of the sign of the frequency. Our theory provides a method of a remote probing and measurement of electron density gradients in plasma; this is based on the demonstrated asymmetry of the Thomson scattering lines.

A theoretical study of hot plasma spheroids in the presence of low-frequency electromagnetic waves

NASA Astrophysics Data System (ADS)

Ahmadizadeh, Y.; Jazi, B.; Barjesteh, S.

2016-07-01

While taking into account thermal motion of electrons, scattering of electromagnetic waves with low frequency from hot plasma spheroids is investigated. In this theoretical research, ions are heavy to respond to electromagnetic fluctuations. The solution of scalar wave equation in spheroidal coordinates for electric potential inside the plasma spheroids are obtained. The variations of resonance frequencies vs. Debye length are studied and consistency between the obtained results in this paper and the results for the well-known plasma objects such as plasma column and spherical plasma have been proved.

Modeling of microwave scattering from vegetated covered terrain

NASA Technical Reports Server (NTRS)

Lang, R. H.

1982-01-01

General formulation of resonant backscattering from vegetation, mean field and Green's function in three media, and electromagnetic backscattering coefficients from a layer of vegetation are discussed.

T-Matrix Method and its Applications to Electromagnetic Scattering by Particles: A Current Perspective

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Travis, Larry D.; Mackowski, Daniel W.

2010-01-01

This note serves as a short introduction to the reprint of our article "T-matrix computations of light scattering by nonspherical particles: a review" (JQSRT 1996; 55:535:75). We first discuss the motivation for writing that article and explain its historical context. This is followed by a short overview of more recent developments.

Hadron Spectra, Decays and Scattering Properties Within Basis Light Front Quantization

NASA Astrophysics Data System (ADS)

Vary, James P.; Adhikari, Lekha; Chen, Guangyao; Jia, Shaoyang; Li, Meijian; Li, Yang; Maris, Pieter; Qian, Wenyang; Spence, John R.; Tang, Shuo; Tuchin, Kirill; Yu, Anji; Zhao, Xingbo

2018-07-01

We survey recent progress in calculating properties of the electron and hadrons within the basis light front quantization (BLFQ) approach. We include applications to electromagnetic and strong scattering processes in relativistic heavy ion collisions. We present an initial investigation into the glueball states by applying BLFQ with multigluon sectors, introducing future research possibilities on multi-quark and multi-gluon systems.

Scattering from the Finite-Length, Dielectric Circular Cylinder: Part I - Derivation of an Analytical Solution

DTIC Science & Technology

2015-07-01

lph s iS k k here match the formulations from Karam et al.17 (Note that there are typographical errors in Eq. 25 of that journal article.17) 3...mixed-species forests. IEEE Trans Geosci Rem Sens. 2005;43(11):2612–2626. 17. Karam MA, Fung AK, Antar YMM. Electromagnetic wave scattering from some

Scattering from a quantum anapole at low energies

NASA Astrophysics Data System (ADS)

Whitcomb, Kyle M.; Latimer, David C.

2017-12-01

In quantum field theory, the photon-fermion vertex can be described in terms of four form-factors that encode the static electromagnetic properties of the particle, namely, its charge, magnetic dipole moment, electric dipole moment, and anapole moment. For Majorana fermions, only the anapole moment can be nonzero, a consequence of the fact that these particles are their own antiparticles. Using the framework of quantum field theory, we perform a scattering calculation that probes the anapole moment with a spinless charged particle. In the limit of low momentum transfer, we confirm that the anapole can be classically likened to a point-like toroidal solenoid whose magnetic field is confined to the origin. Such a toroidal current distribution can be used to demonstrate the Aharonov-Bohm effect. We find that, in the non-relativistic limit, our scattering cross section agrees with a quantum mechanical computation of the cross section for a spinless current scattered by an infinitesimally thin toroidal solenoid. Our presentation is geared toward advanced undergraduate or beginning graduate students. This work serves as an introduction to the anapole moment and also provides an example of how one can develop an understanding of a particle's electromagnetic properties in quantum field theory.

Manipulation of polarization anisotropy in bare InAs and InAs/GaSb core-shell nanowires

NASA Astrophysics Data System (ADS)

Patra, Atanu; Roy, Anushree; Gomes, Umesh Prasad; Zannier, Valentina; Ercolani, Daniele; Sorba, Lucia

2018-04-01

In this article, we compare the excitation wavelength dependence of the polarization anisotropy (ρ) of an internal field induced Raman scattering signal in individual bare InAs and InAs/GaSb core-shell nanowires. The measured value of ρ of the Raman scattering intensity for InAs/GaSb core-shell nanowires has a minimum at ˜500 nm, while for the bare InAs nanowire, the value of ρ monotonically increases over the same range of wavelengths. We have modeled the scattering intensities of both systems by considering the joint role of Raman tensor components and confinement of electromagnetic radiation inside the nanowire at two orthogonal polarization configurations of the electromagnetic radiation. The theoretical results allow us to understand that the observed behavior of ρ is related to the nanowire geometry and to the difference in the wavelength dependence of the dielectric constants of InAs and GaSb. This work shows the possibility of manipulating the polarization anisotropy by selecting suitable diameters and materials for the core and the shell of the nanowire. We also report a six-fold increase in Raman scattering intensity due to the GaSb shell on InAs nanowires.

Microwave Remote Sensing of Falling Snow

NASA Technical Reports Server (NTRS)

Kim, Min-Jeong; Wang, J. R.; Meneghini, R.; Johnson, B.; Tanelli, S.; Roman-Nieves, J. I.; Sekelsky, S. M.; Skofronick-Jackson, G.

2005-01-01

This study analyzes passive and active microwave measurements during the 2003 Wakasa Bay field experiment for understanding of the electromagnetic characteristics of frozen hydrometeors at millimeter-wave frequencies. Based on these understandings, parameterizations of the electromagnetic scattering properties of snow at millimeter-wave frequencies are developed and applied to the hydrometeor profiles obtained by airborne radar measurements. Calculated brightness temperatures and radar reflectivity are compared with the millimeter-wave measurements.

Neutral Pion Production in MINERvA

NASA Astrophysics Data System (ADS)

Palomino, Jose

2012-03-01

MINERνA is a neutrino-nucleus scattering experiment employing multiple nuclear targets. The experiment is searching for neutral pion production, both in charged current and neutral current, from coherent, resonant and deep-inelastic processes off these targets. Neutral pions are detected through the 2 photon decay that then produce electromagnetic showers. We will describe how we isolate and reconstruct the electromagnetic showers to calculate the invariant mass of the photon pair.

Chevron beam dump for ITER edge Thomson scattering system.

PubMed

Yatsuka, E; Hatae, T; Vayakis, G; Bassan, M; Itami, K

2013-10-01

This paper contains the design of the beam dump for the ITER edge Thomson scattering system and mainly concerns its lifetime under the harsh thermal and electromagnetic loads as well as tight space allocation. The lifetime was estimated from the multi-pulse laser-induced damage threshold. In order to extend its lifetime, the structure of the beam dump was optimized. A number of bent sheets aligned parallel in the beam dump form a shape called a chevron which enables it to avoid the concentration of the incident laser pulse energy. The chevron beam dump is expected to withstand thermal loads due to nuclear heating, radiation from the plasma, and numerous incident laser pulses throughout the entire ITER project with a reasonable margin for the peak factor of the beam profile. Structural analysis was also carried out in case of electromagnetic loads during a disruption. Moreover, detailed issues for more accurate assessments of the beam dump's lifetime are clarified. Variation of the bi-directional reflection distribution function (BRDF) due to erosion by or contamination of neutral particles derived from the plasma is one of the most critical issues that needs to be resolved. In this paper, the BRDF was assumed, and the total amount of stray light and the absorbed laser energy profile on the beam dump were evaluated.

Fluctuating volume-current formulation of electromagnetic fluctuations in inhomogeneous media: Incandescence and luminescence in arbitrary geometries

NASA Astrophysics Data System (ADS)

Polimeridis, Athanasios G.; Reid, M. T. H.; Jin, Weiliang; Johnson, Steven G.; White, Jacob K.; Rodriguez, Alejandro W.

2015-10-01

We describe a fluctuating volume-current formulation of electromagnetic fluctuations that extends our recent work on heat exchange and Casimir interactions between arbitrarily shaped homogeneous bodies [A. W. Rodriguez, M. T. H. Reid, and S. G. Johnson, Phys. Rev. B 88, 054305 (2013), 10.1103/PhysRevB.88.054305] to situations involving incandescence and luminescence problems, including thermal radiation, heat transfer, Casimir forces, spontaneous emission, fluorescence, and Raman scattering, in inhomogeneous media. Unlike previous scattering formulations based on field and/or surface unknowns, our work exploits powerful techniques from the volume-integral equation (VIE) method, in which electromagnetic scattering is described in terms of volumetric, current unknowns throughout the bodies. The resulting trace formulas (boxed equations) involve products of well-studied VIE matrices and describe power and momentum transfer between objects with spatially varying material properties and fluctuation characteristics. We demonstrate that thanks to the low-rank properties of the associated matrices, these formulas are susceptible to fast-trace computations based on iterative methods, making practical calculations tractable. We apply our techniques to study thermal radiation, heat transfer, and fluorescence in complicated geometries, checking our method against established techniques best suited for homogeneous bodies as well as applying it to obtain predictions of radiation from complex bodies with spatially varying permittivities and/or temperature profiles.

Distinguishing non-resonant four-wave-mixing noise in coherent stokes and anti-stokes Raman scattering

NASA Technical Reports Server (NTRS)

Marks, Daniel L. (Inventor); Boppart, Stephen A. (Inventor)

2009-01-01

A method of examining a sample comprises exposing the sample to a pump pulse of electromagnetic radiation for a first period of time, exposing the sample to a stimulant pulse of electromagnetic radiation for a second period of time which overlaps in time with at least a portion of the first exposing, to produce a signal pulse of electromagnetic radiation for a third period of time, and interfering the signal pulse with a reference pulse of electromagnetic radiation, to determine which portions of the signal pulse were produced during the exposing of the sample to the stimulant pulse. The first and third periods of time are each greater than the second period of time.

Pushing, pulling and electromagnetic radiation force cloaking by a pair of conducting cylindrical particles

NASA Astrophysics Data System (ADS)

Mitri, F. G.

2018-02-01

The present analysis shows that two conducting cylindrical particles illuminated by an axially-polarized electric field of plane progressive waves at arbitrary incidence will attract, repel or become totally cloaked (i.e., invisible to the transfer of linear momentum carried by the incident waves), depending on their sizes, the interparticle distance as well as the angle of incidence of the incident field. Based on the rigorous multipole expansion method and the translational addition theorem of cylindrical wave functions, the electromagnetic (EM) radiation forces arising from multiple scattering effects between a pair of perfectly conducting cylindrical particles of circular cross-sections are derived and computed. An effective incident field on a particular particle is determined first, and used subsequently with its corresponding scattered field to derive the closed-form analytical expressions for the radiation force vector components. The mathematical expressions for the EM radiation force components (i.e. longitudinal and transverse) are exact, and have been formulated in partial-wave series expansions in cylindrical coordinates involving the angle of incidence, the interparticle distance and the expansion coefficients. Numerical examples illustrate the analysis for two perfectly conducting circular cylinders in a homogeneous nonmagnetic medium of wave propagation. The computations for the dimensionless radiation force functions are performed with particular emphasis on varying the angle of incidence, the interparticle distance, and the sizes of the particles. Depending on the interparticle distance and angle of incidence, the cylinders yield total neutrality (or invisibility); they experience no force and become unresponsive to the transfer of the EM linear momentum due to multiple scattering cancellation effects. Moreover, pushing or pulling EM forces between the two cylinders arise depending on the interparticle distance, the angle of incidence and their size parameters. This study provides a complete analytical method and computations for the longitudinal and transverse radiation force components in the multiple scattering of EM plane progressive waves with potential applications in particle manipulation, optically-engineered metamaterials with reconfigurable periodicities and cloaking devices to name a few examples.

An efficient high-frequency analysis of modal reflection and transmission coefficients for a class of waveguide discontinuities

NASA Technical Reports Server (NTRS)

Pathak, P. H.; Altintas, A.

1988-01-01

A high-frequency analysis of electromagnetic modal reflection and transmission coefficients is presented for waveguide discontinuities formed by joining different waveguide sections. The analysis uses an extended version of the concept of geometrical theory of diffraction based equivalent edge currents in conjunction with the reciprocity theorem to describe interior scattering effects. If the waveguide modes and their associated modal rays can be found explicitly, general two- and three-dimensional waveguide geometries can be analyzed. Expressions are developed for two-dimensional reflection and transmission coefficients. Numerical results are given for a flanged, semi-infinite parallel plate waveguide and for the junction between two linearly tapered waveguides.

Nonlinear resonance scattering of femtosecond X-ray pulses on atoms in plasmas

NASA Astrophysics Data System (ADS)

Rosmej, F. B.; Astapenko, V. A.; Lisitsa, V. S.; Moroz, N. N.

2017-11-01

It is shown that for sufficiently short pulses the resonance scattering probability becomes a nonlinear function of the pulse duration. For fs X-ray pulses scattered on atoms in plasmas maxima and minima develop in the nonlinear regime whereas in the limit of long pulses the probability becomes linear and turns over into the standard description of the electromagnetic pulse scattering. Numerical calculations are carried out in terms of a generalized scattering probability for the total time of pulse duration including fine structure splitting and ion Doppler broadening in hot plasmas. For projected X-ray monocycles, the generalized nonlinear approach differs by 1-2 orders of magnitude from the standard theory.

Electromagnetic Scattering by Spheroidal Volumes of Discrete Random Medium

NASA Technical Reports Server (NTRS)

Dlugach, Janna M.; Mishchenko, Michael I.

2017-01-01

We use the superposition T-matrix method to compare the far-field scattering matrices generated by spheroidal and spherical volumes of discrete random medium having the same volume and populated by identical spherical particles. Our results fully confirm the robustness of the previously identified coherent and diffuse scattering regimes and associated optical phenomena exhibited by spherical particulate volumes and support their explanation in terms of the interference phenomenon coupled with the order-of-scattering expansion of the far-field Foldy equations. We also show that increasing non-sphericity of particulate volumes causes discernible (albeit less pronounced) optical effects in forward and backscattering directions and explain them in terms of the same interference/multiple-scattering phenomenon.

The leaf-shape effect on electromagnetic scattering from vegetated media

NASA Technical Reports Server (NTRS)

Karam, M. A.; Fung, A. K.; Blanchard, A. J.; Shen, G. X.

1988-01-01

Using the generalized Rayleigh Gans approximation along with the radiative transfer method, a bistatic backscattering model for a layer of randomly oriented, elliptic-shaped leaves is formulated. Following a similar procedure the bistatic scattering model for a layer of needle-shaped leaves is also developed to simulate coniferous vegetation. The differences between the scattering characteristics of the deciduous and coniferous leaves are illustrated numerically for different orientation and incidence angles. It is found that both like and cross polarizations are needed to differentiate the difference in scattering due to the shapes of the scatterers. The calculated backscattering coefficients are compared with measured values from artificial canopies with circular-shaped leaves.

A review and reassessment of diffraction, scattering, and shadows in electrodynamics

NASA Astrophysics Data System (ADS)

Berg, Matthew J.; Sorensen, Christopher M.

2018-05-01

The concepts of diffraction and scattering are well known and considered fundamental in optics and other wave phenomena. For any type of wave, one way to define diffraction is the spreading of waves, i.e., no change in the average propagation direction, while scattering is the deflection of waves with a clear change of propagation direction. However, the terms "diffraction" and "scattering" are often used interchangeably, and hence, a clear distinction between the two is difficult to find. This review considers electromagnetic waves and retains the simple definition that diffraction is the spreading of waves but demonstrates that all diffraction patterns are the result of scattering. It is shown that for electromagnetic waves, the "diffracted" wave from an object is the Ewald-Oseen extinction wave in the far-field zone. The intensity distribution of this wave yields what is commonly called the diffraction pattern. Moreover, this is the same Ewald-Oseen wave that cancels the incident wave inside the object and thereafter continues to do so immediately behind the object to create a shadow. If the object is much wider than the beam but has a hole, e.g., a screen with an aperture, the Ewald-Oseen extinction wave creates the shadow behind the screen and the incident light that passes through the aperture creates the diffraction pattern. This point of view also illustrates Babinet's principle. Thus, it is the Ewald-Oseen extinction theorem that binds together diffraction, scattering, and shadows.

The FLAME-slab method for electromagnetic wave scattering in aperiodic slabs

NASA Astrophysics Data System (ADS)

Mansha, Shampy; Tsukerman, Igor; Chong, Y. D.

2017-12-01

The proposed numerical method, "FLAME-slab," solves electromagnetic wave scattering problems for aperiodic slab structures by exploiting short-range regularities in these structures. The computational procedure involves special difference schemes with high accuracy even on coarse grids. These schemes are based on Trefftz approximations, utilizing functions that locally satisfy the governing differential equations, as is done in the Flexible Local Approximation Method (FLAME). Radiation boundary conditions are implemented via Fourier expansions in the air surrounding the slab. When applied to ensembles of slab structures with identical short-range features, such as amorphous or quasicrystalline lattices, the method is significantly more efficient, both in runtime and in memory consumption, than traditional approaches. This efficiency is due to the fact that the Trefftz functions need to be computed only once for the whole ensemble.

Surface-enhanced Raman scattering on periodic metal nanotips with tunable sharpness.

PubMed

Linn, Nicholas C; Sun, Chih-Hung; Arya, Ajay; Jiang, Peng; Jiang, Bin

2009-06-03

This paper reports on a scalable bottom-up technology for producing periodic gold nanotips with tunable sharpness as surface-enhanced Raman scattering (SERS) substrates. Inverted silicon pyramidal pits, which are templated from non-close-packed colloidal crystals prepared by a spin-coating technology, are used as structural templates to replicate arrays of polymer nanopyramids with nanoscale sharp tips. The deposition of a thin layer of gold on the polymer nanopyramids leads to the formation of SERS-active substrates with a high enhancement factor (up to 10(8)). The thickness of the deposited metal determines the sharpness of the nanotips and the resulting Raman enhancement factor. Finite-element electromagnetic modeling shows that the nanotips can significantly enhance the local electromagnetic field and the sharpness of nanotips greatly affects the SERS enhancement.

Experimental and theoretical determination of sea-state bias in radar altimetry

NASA Technical Reports Server (NTRS)

Stewart, Robert H.

1991-01-01

The major unknown error in radar altimetry is due to waves on the sea surface which cause the mean radar-reflecting surface to be displaced from mean sea level. This is the electromagnetic bias. The primary motivation for the project was to understand the causes of the bias so that the error it produces in radar altimetry could be calculated and removed from altimeter measurements made from space by the Topex/Poseidon altimetric satellite. The goals of the project were: (1) observe radar scatter at vertical incidence using a simple radar on a platform for a wide variety of environmental conditions at the same time wind and wave conditions were measured; (2) calculate electromagnetic bias from the radar observations; (3) investigate the limitations of the present theory describing radar scatter at vertical incidence; (4) compare measured electromagnetic bias with bias calculated from theory using measurements of wind and waves made at the time of the radar measurements; and (5) if possible, extend the theory so bias can be calculated for a wider range of environmental conditions.

Surface enhanced Raman optical activity of molecules on orientationally averaged substrates: theory of electromagnetic effects.

PubMed

Janesko, Benjamin G; Scuseria, Gustavo E

2006-09-28

We present a model for electromagnetic enhancements in surface enhanced Raman optical activity (SEROA) spectroscopy. The model extends previous treatments of SEROA to substrates, such as metal nanoparticles in solution, that are orientationally averaged with respect to the laboratory frame. Our theoretical treatment combines analytical expressions for unenhanced Raman optical activity with molecular polarizability tensors that are dressed by the substrate's electromagnetic enhancements. We evaluate enhancements from model substrates to determine preliminary scaling laws and selection rules for SEROA. We find that dipolar substrates enhance Raman optical activity (ROA) scattering less than Raman scattering. Evanescent gradient contributions to orientationally averaged ROA scale to first or higher orders in the gradient of the incident plane-wave field. These evanescent gradient contributions may be large for substrates with quadrupolar responses to the plane-wave field gradient. Some substrates may also show a ROA contribution that depends only on the molecular electric dipole-electric dipole polarizability. These conclusions are illustrated via numerical calculations of surface enhanced Raman and ROA spectra from (R)-(-)-bromochlorofluoromethane on various model substrates.

Absorptive coding metasurface for further radar cross section reduction

NASA Astrophysics Data System (ADS)

Sui, Sai; Ma, Hua; Wang, Jiafu; Pang, Yongqiang; Feng, Mingde; Xu, Zhuo; Qu, Shaobo

2018-02-01

Lossless coding metasurfaces and metamaterial absorbers have been widely used for radar cross section (RCS) reduction and stealth applications, which merely depend on redirecting electromagnetic wave energy into various oblique angles or absorbing electromagnetic energy, respectively. Here, an absorptive coding metasurface capable of both the flexible manipulation of backward scattering and further wideband bistatic RCS reduction is proposed. The original idea is carried out by utilizing absorptive elements, such as metamaterial absorbers, to establish a coding metasurface. We establish an analytical connection between an arbitrary absorptive coding metasurface arrangement of both the amplitude and phase and its far-field pattern. Then, as an example, an absorptive coding metasurface is demonstrated as a nonperiodic metamaterial absorber, which indicates an expected better performance of RCS reduction than the traditional lossless coding metasurface and periodic metamaterial-absorber. Both theoretical analysis and full-wave simulation results show good accordance with the experiment.

Asymptotic Solutions for Optical Properties of Large Particles with Strong Absorption

NASA Technical Reports Server (NTRS)

Yang, Ping; Gao, Bo-Cai; Baum, Bryan A.; Hu, Yong X.; Wiscombe, Warren J.; Mishchenko, Michael I.; Winker, Dave M.; Nasiri, Shaima L.; Einaudi, Franco (Technical Monitor)

2000-01-01

For scattering calculations involving nonspherical particles such as ice crystals, we show that the transverse wave condition is not applicable to the refracted electromagnetic wave in the context of geometric optics when absorption is involved. Either the TM wave condition (i.e., where the magnetic field of the refracted wave is transverse with respect to the wave direction) or the TE wave condition (i.e., where the electric field is transverse with respect to the propagating direction of the wave) may be assumed for the refracted wave in an absorbing medium to locally satisfy the electromagnetic boundary condition in the ray tracing calculation. The wave mode assumed for the refracted wave affects both the reflection and refraction coefficients. As a result, a nonunique solution for these coefficients is derived from the electromagnetic boundary condition. In this study we have identified the appropriate solution for the Fresnel reflection/refraction coefficients in light scattering calculation based on the ray tracing technique. We present the 3 x 2 refraction or transmission matrix that completely accounts for the inhomogeneity of the refracted wave in an absorbing medium. Using the Fresnel coefficients for an absorbing medium, we derive an asymptotic solution in an analytical format for the scattering properties of a general polyhedral particle. Numerical results are presented for hexagonal plates and columns with both preferred and random orientations. The asymptotic theory can produce reasonable accuracy in the phase function calculations in the infrared window region (wavelengths near 10 micron) if the particle size (in diameter) is on the order of 40 micron or larger. However, since strong absorption is assumed in the computation of the single-scattering albedo in the asymptotic theory, the single scattering albedo does not change with variation of the particle size. As a result, the asymptotic theory can lead to substantial errors in the computation of single-scattering albedo for small and moderate particle sizes. However, from comparison of the asymptotic results with the FDTD solution, it is expected that a convergence between the FDTD results and the asymptotic theory results can be reached when the particle size approaches 200 micron. We show that the phase function at side-scattering and backscattering angles is insensitive to particle shape if the random orientation condition is assumed. However, if preferred orientations are assumed for particles, the phase function has a strong dependence on scattering azimuthal angle. The single-scattering albedo also shows very strong dependence on the inclination angle of incident radiation with respect to the rotating axis for the preferred particle orientations.

Analysis of forward scattering of an acoustical zeroth-order Bessel beam from rigid complicated (aspherical) structures

NASA Astrophysics Data System (ADS)

Li, Wei; Chai, Yingbin; Gong, Zhixiong; Marston, Philip L.

2017-10-01

The forward scattering from rigid spheroids and endcapped cylinders with finite length (even with a large aspect ratio) immersed in a non-viscous fluid under the illumination of an idealized zeroth-order acoustical Bessel beam (ABB) with arbitrary angles of incidence is calculated and analyzed in the implementation of the T-matrix method (TTM). Based on the present method, the incident coefficients of expansion for the incident ABB are derived and simplifying methods are proposed for the numerical accuracy and computational efficiency according to the geometrical symmetries. A home-made MATLAB software package is constructed accordingly, and then verified and validated for the ABB scattering from rigid aspherical obstacles. Several numerical examples are computed for the forward scattering from both rigid spheroids and finite cylinder, with particular emphasis on the aspect ratios, the half-cone angles of ABBs, the incident angles and the dimensionless frequencies. The rectangular patterns of target strength in the (β, θs) domain (where β is the half-cone angle of the ABB and θs is the scattered polar angle) and local/total forward scattering versus dimensionless frequency are exhibited, which could provide new insights into the physical mechanisms of Bessel beam scattering by rigid spheroids and finite cylinders. The ray diagrams in geometrical models for the scattering in the forward half-space and the optical cross-section theorem help to interpret the scattering mechanisms of ABBs. This research work may provide an alternative for the partial wave series solution under certain circumstances interacting with ABBs for complicated obstacles and benefit some related works in optics and electromagnetics.

Light Scattering by Nonspherical Particles

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Travis, Larry D.; Hovenier, Joop W.

1998-01-01

Improved understanding of electromagnetic scattering by nonspherical particles is important to many science and engineering disciplines and was the subject of the Conference on Light Scattering by Nonspherical Particles: Theory, Measurements, and Applications. The conference was held 29 September-1 October 1998 at the Goddard Institute for Space Studies in New York City and brought together 115 participants from 18 countries. The main objective of the conference was to highlight and summarize the rapid advancements in the field, including numerical methods for computing the single and multiple scattering of electromagnetic radiation by nonspherical and heterogeneous particles, measurement approaches, knowledge of characteristic features in scattering patterns, retrieval and remote sensing techniques, nonspherical particle sizing, and various practical applications. The conference consisted of twelve oral and one poster sessions. The presentations were loosely grouped based on broad topical categories. In each of these categories invited review talks highlighted and summarized specific active areas of research. To ensure a high-quality conference, all abstracts submitted had been reviewed by members of the Scientific Organizing Committee for technical merit and content. The conference program was published in the June 1998 issue of the Bulletin of the American Meteorological Society and is available on the World Wide Web at http://www.giss.nasa.gov/-crmim/conference/program.html. Authors of accepted papers and review presentations contributed to a volume of preprints published by the American Meteorological Society' and distributed to participants at the conference.

Nucleon-nucleon scattering from fully dynamical lattice QCD.

PubMed

Beane, S R; Bedaque, P F; Orginos, K; Savage, M J

2006-07-07

We present results of the first fully dynamical lattice QCD determination of nucleon-nucleon scattering lengths in the 1S0 channel and 3S1 - 3D1 coupled channels. The calculations are performed with domain-wall valence quarks on the MILC staggered configurations with a lattice spacing of b = 0.125 fm in the isospin-symmetric limit, and in the absence of electromagnetic interactions.

Phase-coherent elastic scattering of electromagnetic waves from a random array of resonant dielectric ridges on a dielectric substrate: Weak roughness limit

NASA Astrophysics Data System (ADS)

Danila, B.; McGurn, A. R.

2005-03-01

A theoretical discussion is given of the diffuse scattering of p -polarized electromagnetic waves from a vacuum-dielectric interface characterized by a one-dimensional disorder in the form of parallel, Gaussian shaped, dielectric ridges positioned at random on a planar semi-infinite dielectric substrate. The parameters of the surface roughness are chosen so that the surface is characterized as weakly rough with a low ridge concentration. The emphasis is on phase coherent features in the speckle pattern of light scattered from the surface. These features are determined from the intensity-intensity correlation function of the speckle pattern and are studied as functions of the frequency of light for frequencies near the dielectric frequency resonances of the ridge material. In the first part of the study, the ridges on the substrate are taken to be identical, made from either GaAs, NaF, or ZnS. The substrate for all cases is CdS. In a second set of studies, the heights and widths of the ridges are statistically distributed. The effects of these different types of randomness on the scattering from the random array of dielectric ridges is determined near the dielectric resonance frequency of the ridge material. The work presented is an extension of studies [A. B. McGurn and R. M. Fitzgerald, Phys. Rev. B 65, 155414 (2002)] that originally treated only the differential reflection coefficient of the diffuse scattering of light (not speckle correlation functions) from a system of identical ridges. The object of the present work is to demonstrate the effects of the dielectric frequency resonances of the ridge materials on the phase coherent features found in the speckle patterns of the diffusely scattered light. The dielectric frequency resonances are shown to enhance the observation of the weak localization of electromagnetic surface waves at the random interface. The frequencies treated in this work are in the infrared. Previous weak localization studies have concentrated mainly on the visible and ultraviolet.

A High Frequency Analysis of Electromagnetic Plane Wave Scattering by a Fully Illuminated Perfectly Conducting Semi-Infinite Cone.

DTIC Science & Technology

1986-01-01

mn, 5] sin OdOd (B.39) 98 V Due to the orthogonality of the Legendre polynomials (shown in Appendix D), there is only a value when v = v’. This yields... some of his unpublished results. These results were for the special case of axial incidence on the semi- infinite cone, and were useful in verifying my... general solution. I express gratitude to Mr.(Ph.D. Candidate) Ming Cheng Liang for our many hours of discussion, and to my office mate Mr.(Ph.D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blunden, P. G.; Melnitchouk, W.

We examine the two-photon exchange corrections to elastic electron-nucleon scattering within a dispersive approach, including contributions from both nucleon and Δ intermediate states. The dispersive analysis avoids off-shell uncertainties inherent in traditional approaches based on direct evaluation of loop diagrams, and guarantees the correct unitary behavior in the high energy limit. Using empirical information on the electromagnetic nucleon elastic and NΔ transition form factors, we compute the two-photon exchange corrections both algebraically and numerically. Finally, results are compared with recent measurements of e + p to e - p cross section ratios from the CLAS, VEPP-3 and OLYMPUS experiments.

Electromagnetic radiation and nonlinear energy flow in an electron beam-plasma system

NASA Technical Reports Server (NTRS)

Whelan, D. A.; Stenzel, R. L.

1985-01-01

It is shown that the unstable electron-plasma waves of a beam-plasma system can generate electromagnetic radiation in a uniform plasma. The generation mechanism is a scattering of the unstable electron plasma waves off ion-acoustic waves, producing electromagnetic waves whose frequency is near the local plasma frequency. The wave vector and frequency matching conditions of the three-wave mode coupling are experimentally verified. The electromagnetic radiation is observed to be polarized with the electric field parallel to the beam direction, and its source region is shown to be localized to the unstable plasma wave region. The frequency spectrum shows negligible intensity near the second harmonic of the plasma frequency. These results suggest that the observed electromagnetic radiation of type III solar bursts may be generated near the local plasma frequency and observed downstream where the wave frequency is near the harmonic of the plasma frequency.

Axisymmetric charge-conservative electromagnetic particle simulation algorithm on unstructured grids: Application to microwave vacuum electronic devices

NASA Astrophysics Data System (ADS)

Na, Dong-Yeop; Omelchenko, Yuri A.; Moon, Haksu; Borges, Ben-Hur V.; Teixeira, Fernando L.

2017-10-01

We present a charge-conservative electromagnetic particle-in-cell (EM-PIC) algorithm optimized for the analysis of vacuum electronic devices (VEDs) with cylindrical symmetry (axisymmetry). We exploit the axisymmetry present in the device geometry, fields, and sources to reduce the dimensionality of the problem from 3D to 2D. Further, we employ 'transformation optics' principles to map the original problem in polar coordinates with metric tensor diag (1 ,ρ2 , 1) to an equivalent problem on a Cartesian metric tensor diag (1 , 1 , 1) with an effective (artificial) inhomogeneous medium introduced. The resulting problem in the meridian (ρz) plane is discretized using an unstructured 2D mesh considering TEϕ-polarized fields. Electromagnetic field and source (node-based charges and edge-based currents) variables are expressed as differential forms of various degrees, and discretized using Whitney forms. Using leapfrog time integration, we obtain a mixed E - B finite-element time-domain scheme for the full-discrete Maxwell's equations. We achieve a local and explicit time update for the field equations by employing the sparse approximate inverse (SPAI) algorithm. Interpolating field values to particles' positions for solving Newton-Lorentz equations of motion is also done via Whitney forms. Particles are advanced using the Boris algorithm with relativistic correction. A recently introduced charge-conserving scatter scheme tailored for 2D unstructured grids is used in the scatter step. The algorithm is validated considering cylindrical cavity and space-charge-limited cylindrical diode problems. We use the algorithm to investigate the physical performance of VEDs designed to harness particle bunching effects arising from the coherent (resonance) Cerenkov electron beam interactions within micro-machined slow wave structures.

Optimizing Nanoscale Quantitative Optical Imaging of Subfield Scattering Targets

PubMed Central

Henn, Mark-Alexander; Barnes, Bryan M.; Zhou, Hui; Sohn, Martin; Silver, Richard M.

2016-01-01

The full 3-D scattered field above finite sets of features has been shown to contain a continuum of spatial frequency information, and with novel optical microscopy techniques and electromagnetic modeling, deep-subwavelength geometrical parameters can be determined. Similarly, by using simulations, scattering geometries and experimental conditions can be established to tailor scattered fields that yield lower parametric uncertainties while decreasing the number of measurements and the area of such finite sets of features. Such optimized conditions are reported through quantitative optical imaging in 193 nm scatterfield microscopy using feature sets up to four times smaller in area than state-of-the-art critical dimension targets. PMID:27805660

Development of a cross-polarization scattering system for the measurement of internal magnetic fluctuations in the DIII-D tokamak

DOE PAGES

Rhodes, Terry L.; Peebles, William A.; Crocker, Neal A.; ...

2014-08-05

The design and performance of a new cross-polarization scattering (CPS) system for the localized measurement of internal magnetic fluctuations is presented. CPS is a process whereby magnetic fluctuations scatter incident electromagnetic radiation into a perpendicular polarization which is subsequently detected. A new CPS design that incorporates a unique scattering geometry was laboratory tested, optimized, and installed on the DIII-D tokamak. Plasma tests of signal-to-noise, polarization purity, and frequency response indicate proper functioning of the system. Lastly, CPS data show interesting features related to internal MHD perturbations known as sawteeth that are not observed on density fluctuations.

Scattering by a slab containing randomly located cylinders: comparison between radiative transfer and electromagnetic simulation.

PubMed

Roux, L; Mareschal, P; Vukadinovic, N; Thibaud, J B; Greffet, J J

2001-02-01

This study is devoted to the examination of scattering of waves by a slab containing randomly located cylinders. For the first time to our knowledge, the complete transmission problem has been solved numerically. We have compared the radiative transfer theory with a numerical solution of the wave equation. We discuss the coherent effects, such as forward-scattering dip and backscattering enhancement. It is seen that the radiative transfer equation can be used with great accuracy even for optically thin systems whose geometric thickness is comparable with the wavelength. We have also shown the presence of dependent scattering.

Acoustic integrated extinction.

PubMed

Norris, Andrew N

2015-05-08

The integrated extinction (IE) is defined as the integral of the scattering cross section as a function of wavelength. Sohl et al. (2007 J. Acoust. Soc. Am. 122 , 3206-3210. (doi:10.1121/1.2801546)) derived an IE expression for acoustic scattering that is causal, i.e. the scattered wavefront in the forward direction arrives later than the incident plane wave in the background medium. The IE formula was based on electromagnetic results, for which scattering is causal by default. Here, we derive a formula for the acoustic IE that is valid for causal and non-causal scattering. The general result is expressed as an integral of the time-dependent forward scattering function. The IE reduces to a finite integral for scatterers with zero long-wavelength monopole and dipole amplitudes. Implications for acoustic cloaking are discussed and a new metric is proposed for broadband acoustic transparency.

Multiple scattering induced negative refraction of matter waves

PubMed Central

Pinsker, Florian

2016-01-01

Starting from fundamental multiple scattering theory it is shown that negative refraction indices are feasible for matter waves passing a well-defined ensemble of scatterers. A simple approach to this topic is presented and explicit examples for systems of scatterers in 1D and 3D are stated that imply negative refraction for a generic incoming quantum wave packet. Essential features of the effective scattering field, densities and frequency spectrum of scatterers are considered. Additionally it is shown that negative refraction indices allow perfect transmission of the wave passing the ensemble of scatterers. Finally the concept of the superlens is discussed, since it is based on negative refraction and can be extended to matter waves utilizing the observations presented in this paper which thus paves the way to ‘untouchable’ quantum systems in analogy to cloaking devices for electromagnetic waves. PMID:26857266

Methods of satellite oceanography

NASA Technical Reports Server (NTRS)

Stewart, R. H.

1985-01-01

The theoretical basis for remote sensing measurements of climate and ocean dynamics is examined. Consideration is given to: the absorption of electromagnetic radiation in the atmosphere; scattering in the atmosphere; and satellite observations using visible light. Consideration is also given to: the theory of radio scatter from the sea; scatter of centimeter waves from the sea; and the theory of operation of synthetic aperture radars. Additional topics include: the coordinate systems of satellite orbits for oceanographic remote sensing applications; the operating features of the major U.S. satellite systems for viewing the ocean; and satellite altimetry.

A model for the scattering of high-frequency electromagnetic fields from dielectrics exhibiting thermally-activated electrical losses

NASA Technical Reports Server (NTRS)

Hann, Raiford E.

1991-01-01

An equivalent circuit model (ECM) approach is used to predict the scattering behavior of temperature-activated, electrically lossy dielectric layers. The total electrical response of the dielectric (relaxation + conductive) is given by the ECM and used in combination with transmission line theory to compute reflectance spectra for a Dallenbach layer configuration. The effects of thermally-activated relaxation processes on the scattering properties is discussed. Also, the effect of relaxation and conduction activation energy on the electrical properties of the dielectric is described.

A phenomenological π-p scattering length from pionic hydrogen

NASA Astrophysics Data System (ADS)

Ericson, T. E. O.; Loiseau, B.; Wycech, S.

2004-07-01

We derive a closed, model independent, expression for the electromagnetic correction factor to a phenomenological hadronic scattering length ah extracted from a hydrogenic atom. It is obtained in a non-relativistic approach and in the limit of a short ranged hadronic interaction to terms of order α2logα using an extended charge distribution. A hadronic πN scattering length ahπ-p=0.0870(5)mπ-1 is deduced leading to a πNN coupling constant from the GMO relation gc2/(4π)=14.04(17).

Photoacoustic phasoscopy super-contrast imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Fei; Feng, Xiaohua; Zheng, Yuanjin, E-mail: yjzheng@ntu.edu.sg

2014-05-26

Phasoscopy is a recently proposed concept correlating electromagnetic (EM) absorption and scattering properties based on energy conservation. Phase information can be extracted from EM absorption induced acoustic wave and scattered EM wave for biological tissue characterization. In this paper, an imaging modality, termed photoacoustic phasoscopy imaging (PAPS), is proposed and verified experimentally based on phasoscopy concept with laser illumination. Both endogenous photoacoustic wave and scattered photons are collected simultaneously to extract the phase information. The PAPS images are then reconstructed on vessel-mimicking phantom and ex vivo porcine tissues to show significantly improved contrast than conventional photoacoustic imaging.

Scattering of electromagnetic waves from a half-space of randomly distributed discrete scatterers and polarized backscattering ratio law

NASA Technical Reports Server (NTRS)

Zhu, P. Y.

1991-01-01

The effective-medium approximation is applied to investigate scattering from a half-space of randomly and densely distributed discrete scatterers. Starting from vector wave equations, an approximation, called effective-medium Born approximation, a particular way, treating Green's functions, and special coordinates, of which the origin is set at the field point, are used to calculate the bistatic- and back-scatterings. An analytic solution of backscattering with closed form is obtained and it shows a depolarization effect. The theoretical results are in good agreement with the experimental measurements in the cases of snow, multi- and first-year sea-ice. The root product ratio of polarization to depolarization in backscattering is equal to 8; this result constitutes a law about polarized scattering phenomena in the nature.

Does electromagnetic radiation accelerate galactic cosmic rays

NASA Technical Reports Server (NTRS)

Eichler, D.

1977-01-01

The 'reactor' theories of Tsytovich and collaborators (1973) of cosmic-ray acceleration by electromagnetic radiation are examined in the context of galactic cosmic rays. It is shown that any isotropic synchrotron or Compton reactors with reasonable astrophysical parameters can yield particles with a maximum relativistic factor of only about 10,000. If they are to produce particles with higher relativistic factors, the losses due to inverse Compton scattering of the electromagnetic radiation in them outweigh the acceleration, and this violates the assumptions of the theory. This is a critical restriction in the context of galactic cosmic rays, which have a power-law spectrum extending up to a relativistic factor of 1 million.

Explosive electromagnetic radiation by the relaxation of a multimode magnon system.

PubMed

Vasyuchka, V I; Serga, A A; Sandweg, C W; Slobodianiuk, D V; Melkov, G A; Hillebrands, B

2013-11-01

Microwave emission from a parametrically pumped ferrimagnetic film of yttrium iron garnet was studied versus the magnon density evolution, which was detected by Brillouin light scattering spectroscopy. It has been found that the shutdown of external microwave pumping leads to an unexpected effect: The conventional monotonic decrease of the population of parametrically injected magnons is accompanied by an explosive behavior of electromagnetic radiation at the magnon frequency. The developed theory shows that this explosion is caused by a nonlinear energy transfer from parametrically driven short-wavelength dipolar-exchange magnons to a long-wavelength dipolar magnon mode effectively coupled to an electromagnetic wave.

Nonlinear electromagnetic interactions in energetic materials

DOE PAGES

Wood, Mitchell Anthony; Dalvit, Diego Alejandro; Moore, David Steven

2016-01-12

We study the scattering of electromagnetic waves in anisotropic energetic materials. Nonlinear light-matter interactions in molecular crystals result in frequency-conversion and polarization changes. Applied electromagnetic fields of moderate intensity can induce these nonlinear effects without triggering chemical decomposition, offering a mechanism for the nonionizing identification of explosives. We use molecular-dynamics simulations to compute such two-dimensional THz spectra for planar slabs made of pentaerythritol tetranitrate and ammonium nitrate. Finally, we discuss third-harmonic generation and polarization-conversion processes in such materials. These observed far-field spectral features of the reflected or transmitted light may serve as an alternative tool for standoff explosive detection.

Stimulated Brillouin scattering during electron gyro-harmonic heating at EISCAT

NASA Astrophysics Data System (ADS)

Fu, H. Y.; Scales, W. A.; Bernhardt, P. A.; Briczinski, S. J.; Kosch, M. J.; Senior, A.; Rietveld, M. T.; Yeoman, T. K.; Ruohoniemi, J. M.

2015-08-01

Observations of secondary radiation, stimulated electromagnetic emission (SEE), produced during ionospheric modification experiments using ground-based, high-power, high-frequency (HF) radio waves are considered. The High Frequency Active Auroral Research Program (HAARP) facility is capable of generating narrowband SEE in the form of stimulated Brillouin scatter (SBS) and stimulated ion Bernstein scatter (SIBS) in the SEE spectrum. Such narrowband SEE spectral lines have not been reported using the European Incoherent Scatter (EISCAT) heater facility before. This work reports the first EISCAT results of narrowband SEE spectra and compares them to SEE previously observed at HAARP during electron gyro-harmonic heating. An analysis of experimental SEE data shows observations of emission lines within 100 Hz of the pump frequency, interpreted as SBS, during the 2012 July EISCAT campaign. Experimental results indicate that SBS strengthens as the pump frequency approaches the third electron gyro-harmonic. Also, for different heater antenna beam angles, the CUTLASS radar backscatter induced by HF radio pumping is suppressed near electron gyro-harmonics, whereas electron temperature enhancement weakens as measured by EISCAT/UHF radar. The main features of these new narrowband EISCAT observations are generally consistent with previous SBS measurements at HAARP.

A programmable metasurface with dynamic polarization, scattering and focusing control

NASA Astrophysics Data System (ADS)

Yang, Huanhuan; Cao, Xiangyu; Yang, Fan; Gao, Jun; Xu, Shenheng; Li, Maokun; Chen, Xibi; Zhao, Yi; Zheng, Yuejun; Li, Sijia

2016-10-01

Diverse electromagnetic (EM) responses of a programmable metasurface with a relatively large scale have been investigated, where multiple functionalities are obtained on the same surface. The unit cell in the metasurface is integrated with one PIN diode, and thus a binary coded phase is realized for a single polarization. Exploiting this anisotropic characteristic, reconfigurable polarization conversion is presented first. Then the dynamic scattering performance for two kinds of sources, i.e. a plane wave and a point source, is carefully elaborated. To tailor the scattering properties, genetic algorithm, normally based on binary coding, is coupled with the scattering pattern analysis to optimize the coding matrix. Besides, inverse fast Fourier transform (IFFT) technique is also introduced to expedite the optimization process of a large metasurface. Since the coding control of each unit cell allows a local and direct modulation of EM wave, various EM phenomena including anomalous reflection, diffusion, beam steering and beam forming are successfully demonstrated by both simulations and experiments. It is worthwhile to point out that a real-time switch among these functionalities is also achieved by using a field-programmable gate array (FPGA). All the results suggest that the proposed programmable metasurface has great potentials for future applications.

Volume integral equation for electromagnetic scattering: Rigorous derivation and analysis for a set of multilayered particles with piecewise-smooth boundaries in a passive host medium

NASA Astrophysics Data System (ADS)

Yurkin, Maxim A.; Mishchenko, Michael I.

2018-04-01

We present a general derivation of the frequency-domain volume integral equation (VIE) for the electric field inside a nonmagnetic scattering object from the differential Maxwell equations, transmission boundary conditions, radiation condition at infinity, and locally-finite-energy condition. The derivation applies to an arbitrary spatially finite group of particles made of isotropic materials and embedded in a passive host medium, including those with edges, corners, and intersecting internal interfaces. This is a substantially more general type of scatterer than in all previous derivations. We explicitly treat the strong singularity of the integral kernel, but keep the entire discussion accessible to the applied scattering community. We also consider the known results on the existence and uniqueness of VIE solution and conjecture a general sufficient condition for that. Finally, we discuss an alternative way of deriving the VIE for an arbitrary object by means of a continuous transformation of the everywhere smooth refractive-index function into a discontinuous one. Overall, the paper examines and pushes forward the state-of-the-art understanding of various analytical aspects of the VIE.

A programmable metasurface with dynamic polarization, scattering and focusing control

PubMed Central

Yang, Huanhuan; Cao, Xiangyu; Yang, Fan; Gao, Jun; Xu, Shenheng; Li, Maokun; Chen, Xibi; Zhao, Yi; Zheng, Yuejun; Li, Sijia

2016-01-01

Diverse electromagnetic (EM) responses of a programmable metasurface with a relatively large scale have been investigated, where multiple functionalities are obtained on the same surface. The unit cell in the metasurface is integrated with one PIN diode, and thus a binary coded phase is realized for a single polarization. Exploiting this anisotropic characteristic, reconfigurable polarization conversion is presented first. Then the dynamic scattering performance for two kinds of sources, i.e. a plane wave and a point source, is carefully elaborated. To tailor the scattering properties, genetic algorithm, normally based on binary coding, is coupled with the scattering pattern analysis to optimize the coding matrix. Besides, inverse fast Fourier transform (IFFT) technique is also introduced to expedite the optimization process of a large metasurface. Since the coding control of each unit cell allows a local and direct modulation of EM wave, various EM phenomena including anomalous reflection, diffusion, beam steering and beam forming are successfully demonstrated by both simulations and experiments. It is worthwhile to point out that a real-time switch among these functionalities is also achieved by using a field-programmable gate array (FPGA). All the results suggest that the proposed programmable metasurface has great potentials for future applications. PMID:27774997

A programmable metasurface with dynamic polarization, scattering and focusing control.

PubMed

Yang, Huanhuan; Cao, Xiangyu; Yang, Fan; Gao, Jun; Xu, Shenheng; Li, Maokun; Chen, Xibi; Zhao, Yi; Zheng, Yuejun; Li, Sijia

2016-10-24

Diverse electromagnetic (EM) responses of a programmable metasurface with a relatively large scale have been investigated, where multiple functionalities are obtained on the same surface. The unit cell in the metasurface is integrated with one PIN diode, and thus a binary coded phase is realized for a single polarization. Exploiting this anisotropic characteristic, reconfigurable polarization conversion is presented first. Then the dynamic scattering performance for two kinds of sources, i.e. a plane wave and a point source, is carefully elaborated. To tailor the scattering properties, genetic algorithm, normally based on binary coding, is coupled with the scattering pattern analysis to optimize the coding matrix. Besides, inverse fast Fourier transform (IFFT) technique is also introduced to expedite the optimization process of a large metasurface. Since the coding control of each unit cell allows a local and direct modulation of EM wave, various EM phenomena including anomalous reflection, diffusion, beam steering and beam forming are successfully demonstrated by both simulations and experiments. It is worthwhile to point out that a real-time switch among these functionalities is also achieved by using a field-programmable gate array (FPGA). All the results suggest that the proposed programmable metasurface has great potentials for future applications.

On the Validity of Certain Approximations Used in the Modeling of Nuclear EMP

DOE PAGES

Farmer, William A.; Cohen, Bruce I.; Eng, Chester D.

2016-04-01

The legacy codes developed for the modeling of EMP, multiple scattering of Compton electrons has typically been modeled by the obliquity factor. A recent publication has examined this approximation in the context of the generated Compton current [W. A. Farmer and A. Friedman, IEEE Trans. Nucl. Sc. 62, 1695 (2015)]. Here, this previous analysis is extended to include the generation of the electromagnetic fields. Obliquity factor predictions are compared with Monte-Carlo models. In using a Monte-Carlo description of scattering, two distributions of scattering angles are considered: Gaussian and a Gaussian with a single-scattering tail. Additionally, legacy codes also neglect themore » radial derivative of the backward-traveling wave for computational efficiency. The neglect of this derivative improperly treats the backward-traveling wave. Moreover, these approximations are examined in the context of a high-altitude burst, and it is shown that in comparison to more complete models, the discrepancy between field amplitudes is roughly two to three percent and between rise-times, 10%. Finally, it is concluded that the biggest factor in determining the rise time of the signal is not the dynamics of the Compton current, but is instead the conductivity.« less

Electromagnetically induced acoustic emission—novel NDT technique for damage evaluation

NASA Astrophysics Data System (ADS)

Finkel, P.; Godinez, V.; Miller, R.; Finlayson, R.

2001-04-01

A recently developed electromagnetically induced acoustic emission technique (EM AE) which can be used for damage assessment of thin walled conducting structures is described. This technique allows a structure to be loaded locally by applying an electromagnetic field in order to produce an AE response, which may be captured by conventional or fiber optic (FO) AE sensors. The advantage of this technique is that the localized dynamic stresses induced by a short current pulse in the presence of an external magnetic field aid in the detection of cracks. Also, it is shown that electromagnetic stimulation can be applied to enhance conventional ultrasonics by modulation of the scattered signal from the defect (EM UT). Experimental data is presented for the case of a fatigue crack near rivet holes in thin walled aluminum structures.

Active and Passive Radiative Transfer Modeling with Preferentially-Aligned Particles

NASA Technical Reports Server (NTRS)

Adams, Ian Stuart

2017-01-01

The fluid dynamics of falling hydrometeors often results in preferential orientations that can affect both the intensity and polarization of electromagnetic radiation. In order to properly interpret remote sensing observations of ice and snow, such alignments should be considered when constructing databases of scattering particles; however, the inclusion of aligned particles increases the complexity of the scattering data. To demonstrate the use of scattering properties of preferentially-aligned particles, millimeter-wave brightness temperatures and radar observables, including reflectivity and linear depolarization ratio, are modeled using the Atmospheric Radiative Transfer Simulator (ARTS). The necessary scattering parameters for vector radiative transfer, particularly with respect to ARTS, are reviewed, and the exploitation of particle symmetries, as well as scattering reciprocity relationships, are detailed.

High-order integral equation methods for problems of scattering by bumps and cavities on half-planes.

PubMed

Pérez-Arancibia, Carlos; Bruno, Oscar P

2014-08-01

This paper presents high-order integral equation methods for the evaluation of electromagnetic wave scattering by dielectric bumps and dielectric cavities on perfectly conducting or dielectric half-planes. In detail, the algorithms introduced in this paper apply to eight classical scattering problems, namely, scattering by a dielectric bump on a perfectly conducting or a dielectric half-plane, and scattering by a filled, overfilled, or void dielectric cavity on a perfectly conducting or a dielectric half-plane. In all cases field representations based on single-layer potentials for appropriately chosen Green functions are used. The numerical far fields and near fields exhibit excellent convergence as discretizations are refined-even at and around points where singular fields and infinite currents exist.

A Theory of Radar Scattering by the Moon

NASA Technical Reports Server (NTRS)

Senior, T. B. A.; Siegel, K. M.

1959-01-01

A theory is described in which the moon is regarded as a "quasi-smooth" scatterer at radar frequencies. A scattered pulse is then composed of a number of individual returns each of which is provided by a single scattering area. In this manner it is possible to account for all the major features of the pulse, and the evidence in favor of the theory is presented. From a study of the measured power received at different frequencies, it is shown that the scattering area nearest to the earth is the source of a specular return, and it is then possible to obtain information about the material of which the area is composed. The electromagnetic constants are derived and their significance discussed.

Electromagnetic Scattering From a Polygonal Thin Metallic Plate Using Quadrilateral Meshing

NASA Technical Reports Server (NTRS)

Deshpande, Manohar D.

2003-01-01

The problem of electromagnetic (EM) scattering from irregularly shaped, thin, metallic flat plates in free space is solved using the electric field integral equation (EFIE) approach in conjunction with the method of moments (MoM) with quadrilateral meshing. An irregularly shaped thin plate is discretized into quadrilateral patches and the unknown electric surface current over the plate is expressed in terms of proper basis functions over these patches. The basis functions for the electric surface current density that satisfy the proper boundary conditions on these quadrilateral patches are derived. The unknown surface current density on these quadrilateral patches is determined by setting up and solving the electric field integral equation by the application of the MoM. From the knowledge of the surface current density, the EM scattering from various irregularly shaped plates is determined and compared with the earlier published results. The novelty in the present approach is the use of quadrilateral patches instead of well known and often used triangular patches. The numerical results obtained using the quadrilateral patches compare favorably with measured results.

Plasmonic Horizon in Gold Nanosponges.

PubMed

Vidal, Cynthia; Sivun, Dmitry; Ziegler, Johannes; Wang, Dong; Schaaf, Peter; Hrelescu, Calin; Klar, Thomas A

2018-02-14

An electromagnetic wave impinging on a gold nanosponge coherently excites many electromagnetic hot-spots inside the nanosponge, yielding a polarization-dependent scattering spectrum. In contrast, a hole, recombining with an electron, can locally excite plasmonic hot-spots only within a horizon given by the lifetime of localized plasmons and the speed carrying the information that a plasmon has been created. This horizon is about 57 nm, decreasing with increasing size of the nanosponge. Consequently, photoluminescence from large gold nanosponges appears unpolarized.

Applied Computational Electromagnetics Society Journal, volume 9, number 1, March 1994

NASA Astrophysics Data System (ADS)

1994-03-01

The partial contents of this document include the following: On the Use of Bivariate Spline Interpolation of Slot Data in the Design of Slotted Waveguide Arrays; A Technique for Determining Non-Integer Eigenvalues for Solutions of Ordinary Differential Equations; Antenna Modeling and Characterization of a VLF Airborne Dual Trailing Wire Antenna System; Electromagnetic Scattering from Two-Dimensional Composite Objects; and Use of a Stealth Boundary with Finite Difference Frequency Domain Simulations of Simple Antenna Problems.

Electromagnetic waves in a model with Chern-Simons potential.

PubMed

Pis'mak, D Yu; Pis'mak, Yu M; Wegner, F J

2015-07-01

We investigated the appearance of Chern-Simons terms in electrodynamics at the surface or interface of materials. The requirement of locality, gauge invariance, and renormalizability in this model is imposed. Scattering and reflection of electromagnetic waves in three different homogeneous layers of media is determined. Snell's law is preserved. However, the transmission and reflection coefficient depend on the strength of the Chern-Simons interaction (connected with Hall conductance), and parallel and perpendicular components are mixed.

Niobium pentoxide: a promising surface-enhanced Raman scattering active semiconductor substrate

NASA Astrophysics Data System (ADS)

Shan, Yufeng; Zheng, Zhihui; Liu, Jianjun; Yang, Yong; Li, Zhiyuan; Huang, Zhengren; Jiang, Dongliang

2017-03-01

Surface-enhanced Raman scattering technique, as a powerful tool to identify the molecular species, has been severely restricted to the noble metals. The surface-enhanced Raman scattering substrates based on semiconductors would overcome the shortcomings of metal substrates and promote development of surface-enhanced Raman scattering technique in surface science, spectroscopy, and biomedicine studies. However, the detection sensitivity and enhancement effects of semiconductor substrates are suffering from their weak activities. In this work, a semiconductor based on Nb2O5 is reported as a new candidate for highly sensitive surface-enhanced Raman scattering detection of dye molecules. The largest enhancement factor value greater than 107 was observed with the laser excitation at 633 and 780 nm for methylene blue detection. As far as literature review shows, this is in the rank of the highest sensitivity among semiconductor materials; even comparable to the metal nanostructure substrates with "hot spots". The impressive surface-enhanced Raman scattering activities can be attributed to the chemical enhancement dominated by the photo-induced charge transfer, as well as the electromagnetic enhancement, which have been supported by the density-functional-theory and finite element method calculation results. The chemisorption of dye on Nb2O5 creates a new highest occupied molecular orbital and lowest unoccupied molecular orbital contributed by both fragments in the molecule-Nb2O5 system, which makes the charge transfer more feasible with longer excitation wavelength. In addition, the electromagnetic enhancement mechanism also accounts for two orders of magnitude enhancement in the overall enhancement factor value. This work has revealed Nb2O5 nanoparticles as a new semiconductor surface-enhanced Raman scattering substrate that is able to replace noble metals and shows great potentials applied in the fields of biology related.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cornelis de Jager

The experimental and theoretical status of elastic electron scattering from the nucleon is reviewed. As a consequence of new experimental facilities, data of unprecedented precision have recently become available for the electromagnetic and the strange form factors of the nucleon.

Chronic Electromagnetic Exposure at Occupational Safety Level Does Not Affect the Metabolic Profile nor Cornea Healing after LASIK Surgery

PubMed Central

Dabouis, Vincent; Gentilhomme, Edgar; Vignal, Rodolphe; Bourbon, Fréderic; Fauvelle, Florence; Debouzy, Jean-Claude

2014-01-01

LASIK eye surgery has become a very common practice for myopic people, especially those in the military. Sometimes undertaken by people who need to keep a specific medical aptitude, this surgery could be performed in secret from the hierarchy and from the institute medical staff. However, even though the eyes have been previously described as one of the most sensitive organs to electromagnetic fields in the human body, no data exist on the potential deleterious effects of electromagnetic fields on the healing eye. The consequences of chronic long-lasting radar exposures at power density, in accordance with the occupational safety standards (9.71 GHz, 50 W/m2), were investigated on cornea healing. The metabolic and clinical statuses after experimental LASIK keratotomy were assessed on the different eye segments in a New Zealand rabbit model. The analysis methods were performed after 5 months of exposure (1 hour/day, 3 times/week). Neither clinical or histological examinations, nor experimental data, such as light scattering, 1H-NMR HRMAS metabolomics, 13C-NMR spectra of lipidic extracts, and antioxidant status, evidenced significant modifications. It was concluded that withdrawing the medical aptitude of people working in electromagnetic field environments (i.e., radar operators in the navy) after eye surgery was not justified. PMID:24757560

Illusions and Cloaks for Surface Waves

PubMed Central

McManus, T. M.; Valiente-Kroon, J. A.; Horsley, S. A. R.; Hao, Y.

2014-01-01

Ever since the inception of Transformation Optics (TO), new and exciting ideas have been proposed in the field of electromagnetics and the theory has been modified to work in such fields as acoustics and thermodynamics. The most well-known application of this theory is to cloaking, but another equally intriguing application of TO is the idea of an illusion device. Here, we propose a general method to transform electromagnetic waves between two arbitrary surfaces. This allows a flat surface to reproduce the scattering behaviour of a curved surface and vice versa, thereby giving rise to perfect optical illusion and cloaking devices, respectively. The performance of the proposed devices is simulated using thin effective media with engineered material properties. The scattering of the curved surface is shown to be reproduced by its flat analogue (for illusions) and vice versa for cloaks. PMID:25145953

Estimation of Moisture Content of Forest Canopy and Floor from SAR Data Part I: Volume Scattering Case

NASA Technical Reports Server (NTRS)

Moghaddam, M.; Saatchi, S.

1996-01-01

To understand and predict the functioning of forest biomes, their interaction with the atmosphere, and their growth rates, the knowledge of moisture content of their canopy and the floor soil is essential. The synthetic aperture radar on airborne and spaceborne platforms has proven to be a flexible tool for measuring electromagnetic back- scattering properties of vegetation related to their moisture content.

Peculiarities of both light and beta-particles scattering by ultrathin diamond-like semiconductor film.

PubMed

Rumyantsev, Vladimir V; Shtaerman, Esfir Y

2008-02-01

Peculiarities of scattering of TM-polarized light wave by a diamond-like crystalline nano-layer are studied. They are due to specific dispersion of n-phonon polaritons localized in the layer. The IR polaritons discussed here (relating to diamond and Si crystals which are nonpolar materials) will only appear if some of the vibration modes become polar, e.g., due to the presence of the surface. As a result of mixing of g- and u-modes of ion oscillations along the (111)-direction in the near-surface layer, it is possible to observe additional (with respect to bulk) scattering of coherent electromagnetic waves of the Stokes and anti-Stokes frequencies. beta-particles can be utilized as an independent tool of study of new semiconductors, in particular thin diamond films. The effect associated with response of a quasi-two-dimensional diamond-like layer to the moving electron field is considered. beta-particle field induces phonon excitation modes to arise in the material. Coupled with the beta-particle electromagnetic modes they generate polaritons. Spectral density of the radiation intensity of the flashed phonon polaritons has been estimated as a function of the layer thickness as well as of the scattering angle and the beta-particle velocity.

An electrical analogy to Mie scattering

PubMed Central

Caridad, José M.; Connaughton, Stephen; Ott, Christian; Weber, Heiko B.; Krstić, Vojislav

2016-01-01

Mie scattering is an optical phenomenon that appears when electromagnetic waves, in particular light, are elastically scattered at a spherical or cylindrical object. A transfer of this phenomenon onto electron states in ballistic graphene has been proposed theoretically, assuming a well-defined incident wave scattered by a perfectly cylindrical nanometer scaled potential, but experimental fingerprints are lacking. We present an experimental demonstration of an electrical analogue to Mie scattering by using graphene as a conductor, and circular potentials arranged in a square two-dimensional array. The tabletop experiment is carried out under seemingly unfavourable conditions of diffusive transport at room-temperature. Nonetheless, when a canted arrangement of the array with respect to the incident current is chosen, cascaded Mie scattering results robustly in a transverse voltage. Its response on electrostatic gating and variation of potentials convincingly underscores Mie scattering as underlying mechanism. The findings presented here encourage the design of functional electronic metamaterials. PMID:27671003

Angular description for 3D scattering centers

NASA Astrophysics Data System (ADS)

Bhalla, Rajan; Raynal, Ann Marie; Ling, Hao; Moore, John; Velten, Vincent J.

2006-05-01

The electromagnetic scattered field from an electrically large target can often be well modeled as if it is emanating from a discrete set of scattering centers (see Fig. 1). In the scattering center extraction tool we developed previously based on the shooting and bouncing ray technique, no correspondence is maintained amongst the 3D scattering center extracted at adjacent angles. In this paper we present a multi-dimensional clustering algorithm to track the angular and spatial behaviors of 3D scattering centers and group them into features. The extracted features for the Slicy and backhoe targets are presented. We also describe two metrics for measuring the angular persistence and spatial mobility of the 3D scattering centers that make up these features in order to gather insights into target physics and feature stability. We find that features that are most persistent are also the most mobile and discuss implications for optimal SAR imaging.

Chevron beam dump for ITER edge Thomson scattering system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yatsuka, E.; Hatae, T.; Bassan, M.

This paper contains the design of the beam dump for the ITER edge Thomson scattering system and mainly concerns its lifetime under the harsh thermal and electromagnetic loads as well as tight space allocation. The lifetime was estimated from the multi-pulse laser-induced damage threshold. In order to extend its lifetime, the structure of the beam dump was optimized. A number of bent sheets aligned parallel in the beam dump form a shape called a chevron which enables it to avoid the concentration of the incident laser pulse energy. The chevron beam dump is expected to withstand thermal loads due tomore » nuclear heating, radiation from the plasma, and numerous incident laser pulses throughout the entire ITER project with a reasonable margin for the peak factor of the beam profile. Structural analysis was also carried out in case of electromagnetic loads during a disruption. Moreover, detailed issues for more accurate assessments of the beam dump's lifetime are clarified. Variation of the bi-directional reflection distribution function (BRDF) due to erosion by or contamination of neutral particles derived from the plasma is one of the most critical issues that needs to be resolved. In this paper, the BRDF was assumed, and the total amount of stray light and the absorbed laser energy profile on the beam dump were evaluated.« less

Radar transponder antenna pattern analysis for the space shuttle

NASA Technical Reports Server (NTRS)

Radcliff, Roger

1989-01-01

In order to improve tracking capability, radar transponder antennas will soon be mounted on the Shuttle solid rocket boosters (SRB). These four antennas, each being identical cavity-backed helices operating at 5.765 GHz, will be mounted near the top of the SRB's, adjacent to the intertank portion of the external tank. The purpose is to calculate the roll-plane pattern (the plane perpendicular to the SRB axes and containing the antennas) in the presence of this complex electromagnetic environment. The large electrical size of this problem mandates an optical (asymptotic) approach. Development of a specific code for this application is beyond the scope of a summer fellowship; thus a general purpose code, the Numerical Electromagnetics Code - Basic Scattering Code, was chosen as the computational tool. This code is based on the modern Geometrical Theory of Diffraction, and allows computation of scattering of bodies composed of canonical problems such as plates and elliptic cylinders. Apertures mounted on a curved surface (the SRB) cannot be accomplished by the code, so an antenna model consisting of wires excited by a method of moments current input was devised that approximated the actual performance of the antennas. The improvised antenna model matched well with measurements taken at the MSFC range. The SRB's, the external tank, and the shuttle nose were modeled as circular cylinders, and the code was able to produce what is thought to be a reasonable roll-plane pattern.

Surface defects evaluation system based on electromagnetic model simulation and inverse-recognition calibration method

NASA Astrophysics Data System (ADS)

Yang, Yongying; Chai, Huiting; Li, Chen; Zhang, Yihui; Wu, Fan; Bai, Jian; Shen, Yibing

2017-05-01

Digitized evaluation of micro sparse defects on large fine optical surfaces is one of the challenges in the field of optical manufacturing and inspection. The surface defects evaluation system (SDES) for large fine optical surfaces is developed based on our previously reported work. In this paper, the electromagnetic simulation model based on Finite-Difference Time-Domain (FDTD) for vector diffraction theory is firstly established to study the law of microscopic scattering dark-field imaging. Given the aberration in actual optical systems, point spread function (PSF) approximated by a Gaussian function is introduced in the extrapolation from the near field to the far field and the scatter intensity distribution in the image plane is deduced. Analysis shows that both diffraction-broadening imaging and geometrical imaging should be considered in precise size evaluation of defects. Thus, a novel inverse-recognition calibration method is put forward to avoid confusion caused by diffraction-broadening effect. The evaluation method is applied to quantitative evaluation of defects information. The evaluation results of samples of many materials by SDES are compared with those by OLYMPUS microscope to verify the micron-scale resolution and precision. The established system has been applied to inspect defects on large fine optical surfaces and can achieve defects inspection of surfaces as large as 850 mm×500 mm with the resolution of 0.5 μm.

Parameter retrieval of chiral metamaterials based on the state-space approach.

PubMed

Zarifi, Davoud; Soleimani, Mohammad; Abdolali, Ali

2013-08-01

This paper deals with the introduction of an approach for the electromagnetic characterization of homogeneous chiral layers. The proposed method is based on the state-space approach and properties of a 4×4 state transition matrix. Based on this, first, the forward problem analysis through the state-space method is reviewed and properties of the state transition matrix of a chiral layer are presented and proved as two theorems. The formulation of a proposed electromagnetic characterization method is then presented. In this method, scattering data for a linearly polarized plane wave incident normally on a homogeneous chiral slab are combined with properties of a state transition matrix and provide a powerful characterization method. The main difference with respect to other well-established retrieval procedures based on the use of the scattering parameters relies on the direct computation of the transfer matrix of the slab as opposed to the conventional calculation of the propagation constant and impedance of the modes supported by the medium. The proposed approach allows avoiding nonlinearity of the problem but requires getting enough equations to fulfill the task which was provided by considering some properties of the state transition matrix. To demonstrate the applicability and validity of the method, the constitutive parameters of two well-known dispersive chiral metamaterial structures at microwave frequencies are retrieved. The results show that the proposed method is robust and reliable.

Hermite scatterers in an ultraviolet sky

NASA Astrophysics Data System (ADS)

Parker, Kevin J.

2017-12-01

The scattering from spherical inhomogeneities has been a major historical topic in acoustics, optics, and electromagnetics and the phenomenon shapes our perception of the world including the blue sky. The long wavelength limit of ;Rayleigh scattering; is characterized by intensity proportional to k4 (or λ-4) where k is the wavenumber and λ is the wavelength. With the advance of nanotechnology, it is possible to produce scatterers that are inhomogeneous with material properties that are functions of radius r, such as concentric shells. We demonstrate that with proper choice of material properties linked to the Hermite polynomials in r, scatterers can have long wavelength scattering behavior of higher powers: k8, k16, and higher. These ;Hermite scatterers; could be useful in providing unique signatures (or colors) to regions where they are present. If suspended in air under white light, the back-scattered spectrum would be shifted from blue towards violet and then ultraviolet as the higher order Hermite scatterers were illuminated.

Electromagnetic wave scattering from some vegetation samples

NASA Technical Reports Server (NTRS)

Karam, Mostafa A.; Fung, Adrian K.; Antar, Yahia M.

1988-01-01

For an incident plane wave, the field inside a thin scatterer (disk and needle) is estimated by the generalized Rayleigh-Gans (GRG) approximation. This leads to a scattering amplitude tensor equal to that obtained via the Rayleigh approximation (dipole term) with a modifying function. For a finite-length cylinder the inner field is estimated by the corresponding field for the same cylinder of infinite lenght. The effects of different approaches in estimating the field inside the scatterer on the backscattering cross section are illustrated numerically for a circular disk, a needle, and a finite-length cylinder as a function of the wave number and the incidence angle. Finally, the modeling predictions are compared with measurements.

Theory of waves incoherently scattered

NASA Technical Reports Server (NTRS)

Bauer, P.

1974-01-01

Electromagnetic waves impinging upon a plasma at frequencies larger than the plasma frequency, suffer weak scattering. The scattering arises from the existence of electron density fluctuations. The received signal corresponds to a particular spatial Fourier component of the fluctuations, the wave vector of which is a function of the wavelength of the radiowave. Wavelengths short with respect to the Debye length of the medium relate to fluctuations due to non-interacting Maxwellian electrons, while larger wavelengths relate to fluctuations due to collective Coulomb interactions. In the latter case, the scattered signal exhibits a spectral distribution which is characteristic of the main properties of the electron and ion gases and, therefore, provides a powerful diagnosis of the state of the ionosphere.

Scattering from finite bodies of translation - Plates, curved surfaces, and noncircular cylinders

NASA Astrophysics Data System (ADS)

Medgyesi-Mitschang, L. N.; Putnam, J. M.

1983-11-01

Electromagnetic scattering from finite, conducting bodies of translation (BOT) is examined using a formulation based on the electric field integral equation (EFIE) and solved by the method of moments (MM). The present approach provides a systematic, unified treatment for a wide class of finite, thin scatterers at all angles of illumination and polarization. Both concave and convex surfaces are considered. An entire-domain Galerkin expansion along one dimension of the body and a piecewise continuous one along the other are used to represent the unknown current variations. The scattering cross sections, obtained with this formulation, are compared with published results using more specialized methods and further confirmed by experimental measurements.

Organo luminescent semiconductor nanocrystal probes for biological applications and process for making and using such probes

DOEpatents

Weiss, Shimon [Pinole, CA; Bruchez, Jr., Marcel; Alivisatos, Paul [Oakland, CA

2008-01-01

A semiconductor nanocrystal compound is described capable of linking to an affinity molecule. The compound comprises (1) a semiconductor nanocrystal capable of emitting electromagnetic radiation and/or absorbing energy, and/or scattering or diffracting electromagnetic radiation--when excited by an electromagnetic radiation source or a particle beam; and (2) an affinity molecule linked to the semiconductor nanocrystal. The semiconductor nanocrystal is linked to an affinity molecule to form a semiconductor nanocrystal probe capable of bonding with a detectable substance. Exposure of the semiconductor nanocrystal to excitation energy will excite the semiconductor nanocrystal causing the emission of electromagnetic radiation. Further described are processes for respectively: making the luminescent semiconductor nanocrystal compound; making the semiconductor nanocrystal probe; and using the probe to determine the presence of a detectable substance in a material.

Evidence for light-by-light scattering in heavy-ion collisions with the ATLAS detector at the LHC

NASA Astrophysics Data System (ADS)

Aaboud, M.; Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Abeloos, B.; Abidi, S. H.; Abouzeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adachi, S.; Adamczyk, L.; Adelman, J.; Adersberger, M.; Adye, T.; Affolder, A. A.; Agatonovic-Jovin, T.; Agheorghiesei, C.; Aguilar-Saavedra, J. A.; Ahlen, S. P.; Ahmadov, F.; Aielli, G.; Akatsuka, S.; Akerstedt, H.; Åkesson, T. P. A.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Alconada Verzini, M. J.; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexopoulos, T.; Alhroob, M.; Ali, B.; Aliev, M.; Alimonti, G.; Alison, J.; Alkire, S. P.; Allbrooke, B. M. M.; Allen, B. W.; Allport, P. P.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Alshehri, A. A.; Alstaty, M.; Alvarez Gonzalez, B.; Álvarez Piqueras, D.; Alviggi, M. G.; Amadio, B. T.; Amaral Coutinho, Y.; Amelung, C.; Amidei, D.; Amor Dos Santos, S. P.; Amorim, A.; Amoroso, S.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, J. K.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Angelidakis, S.; Angelozzi, I.; Angerami, A.; Anghinolfi, F.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antel, C.; Antonelli, M.; Antonov, A.; Antrim, D. J.; Anulli, F.; Aoki, M.; Aperio Bella, L.; Arabidze, G.; Arai, Y.; Araque, J. P.; Araujo Ferraz, V.; Arce, A. T. H.; Ardell, R. E.; Arduh, F. A.; Arguin, J.-F.; Argyropoulos, S.; Arik, M.; Armbruster, A. J.; Armitage, L. J.; Arnaez, O.; Arnold, H.; Arratia, M.; Arslan, O.; Artamonov, A.; Artoni, G.; Artz, S.; Asai, S.; Asbah, N.; Ashkenazi, A.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N. B.; Augsten, K.; Avolio, G.; Axen, B.; Ayoub, M. K.; Azuelos, G.; Baas, A. E.; Baca, M. J.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Bagiacchi, P.; Bagnaia, P.; Baines, J. T.; Bajic, M.; Baker, O. K.; Baldin, E. M.; Balek, P.; Balestri, T.; Balli, F.; Balunas, W. K.; Banas, E.; Banerjee, Sw.; Bannoura, A. A. E.; Barak, L.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisits, M.-S.; Barklow, T.; Barlow, N.; Barnes, S. L.; Barnett, B. M.; Barnett, R. M.; Barnovska-Blenessy, Z.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barranco Navarro, L.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Bartoldus, R.; Barton, A. E.; Bartos, P.; Basalaev, A.; Bassalat, A.; Bates, R. L.; Batista, S. J.; Batley, J. R.; Battaglia, M.; Bauce, M.; Bauer, F.; Bawa, H. S.; Beacham, J. B.; Beattie, M. D.; Beau, T.; Beauchemin, P. H.; Bechtle, P.; Beck, H. P.; Becker, K.; Becker, M.; Beckingham, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bednyakov, V. A.; Bedognetti, M.; Bee, C. P.; Beermann, T. A.; Begalli, M.; Begel, M.; Behr, J. K.; Bell, A. S.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belotskiy, K.; Beltramello, O.; Belyaev, N. L.; Benary, O.; Benchekroun, D.; Bender, M.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez, J.; Benjamin, D. P.; Benoit, M.; Bensinger, J. R.; Bentvelsen, S.; Beresford, L.; Beretta, M.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Beringer, J.; Berlendis, S.; Bernard, N. R.; Bernardi, G.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Berta, P.; Bertella, C.; Bertoli, G.; Bertolucci, F.; Bertram, I. A.; Bertsche, C.; Bertsche, D.; Besjes, G. J.; Bessidskaia Bylund, O.; Bessner, M.; Besson, N.; Betancourt, C.; Bethani, A.; Bethke, S.; Bevan, A. J.; Bianchi, R. M.; Bianco, M.; Biebel, O.; Biedermann, D.; Bielski, R.; Biesuz, N. V.; Biglietti, M.; Bilbao de Mendizabal, J.; Billoud, T. R. V.; Bilokon, H.; Bindi, M.; Bingul, A.; Bini, C.; Biondi, S.; Bisanz, T.; Bittrich, C.; Bjergaard, D. M.; Black, C. W.; Black, J. E.; Black, K. M.; Blackburn, D.; Blair, R. E.; Blazek, T.; Bloch, I.; Blocker, C.; Blue, A.; Blum, W.; Blumenschein, U.; Blunier, S.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Bock, C.; Boehler, M.; Boerner, D.; Bogavac, D.; Bogdanchikov, A. G.; Bohm, C.; Boisvert, V.; Bokan, P.; Bold, T.; Boldyrev, A. S.; Bomben, M.; Bona, M.; Boonekamp, M.; Borisov, A.; Borissov, G.; Bortfeldt, J.; Bortoletto, D.; Bortolotto, V.; Bos, K.; Boscherini, D.; Bosman, M.; Bossio Sola, J. D.; Boudreau, J.; Bouffard, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Boutle, S. K.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bracinik, J.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Breaden Madden, W. D.; Brendlinger, K.; Brennan, A. J.; Brenner, L.; Brenner, R.; Bressler, S.; Briglin, D. L.; Bristow, T. M.; Britton, D.; Britzger, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Broughton, J. H.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruni, A.; Bruni, G.; Bruni, L. S.; Brunt, B. H.; Bruschi, M.; Bruscino, N.; Bryant, P.; Bryngemark, L.; Buanes, T.; Buat, Q.; Buchholz, P.; Buckley, A. G.; Budagov, I. A.; Buehrer, F.; Bugge, M. K.; Bulekov, O.; Bullock, D.; Burckhart, H.; Burdin, S.; Burgard, C. D.; Burger, A. M.; Burghgrave, B.; Burka, K.; Burke, S.; Burmeister, I.; Burr, J. T. P.; Busato, E.; Büscher, D.; Büscher, V.; Bussey, P.; Butler, J. M.; Buttar, C. M.; Butterworth, J. M.; Butti, P.; Buttinger, W.; Buzatu, A.; Buzykaev, A. R.; Cabrera Urbán, S.; Caforio, D.; Cairo, V. M.; Cakir, O.; Calace, N.; Calafiura, P.; Calandri, A.; Calderini, G.; Calfayan, P.; Callea, G.; Caloba, L. P.; Calvente Lopez, S.; Calvet, D.; Calvet, S.; Calvet, T. P.; Camacho Toro, R.; Camarda, S.; Camarri, P.; Cameron, D.; Caminal Armadans, R.; Camincher, C.; Campana, S.; Campanelli, M.; Camplani, A.; Campoverde, A.; Canale, V.; Cano Bret, M.; Cantero, J.; Cao, T.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capua, M.; Carbone, R. M.; Cardarelli, R.; Cardillo, F.; Carli, I.; Carli, T.; Carlino, G.; Carlson, B. T.; Carminati, L.; Carney, R. M. D.; Caron, S.; Carquin, E.; Carrillo-Montoya, G. D.; Carvalho, J.; Casadei, D.; Casado, M. P.; Casolino, M.; Casper, D. W.; Castelijn, R.; Castelli, A.; Castillo Gimenez, V.; Castro, N. F.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Caudron, J.; Cavaliere, V.; Cavallaro, E.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Celebi, E.; Ceradini, F.; Cerda Alberich, L.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cervelli, A.; Cetin, S. A.; Chafaq, A.; Chakraborty, D.; Chan, S. K.; Chan, W. S.; Chan, Y. L.; Chang, P.; Chapman, J. D.; Charlton, D. G.; Chatterjee, A.; Chau, C. C.; Chavez Barajas, C. A.; Che, S.; Cheatham, S.; Chegwidden, A.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, H.; Chen, S.; Chen, S.; Chen, X.; Chen, Y.; Cheng, H. C.; Cheng, H. J.; Cheng, Y.; Cheplakov, A.; Cheremushkina, E.; Cherkaoui El Moursli, R.; Chernyatin, V.; Cheu, E.; Chevalier, L.; Chiarella, V.; Chiarelli, G.; Chiodini, G.; Chisholm, A. S.; Chitan, A.; Chiu, Y. H.; Chizhov, M. V.; Choi, K.; Chomont, A. R.; Chouridou, S.; Chow, B. K. B.; Christodoulou, V.; Chromek-Burckhart, D.; Chu, M. C.; Chudoba, J.; Chuinard, A. J.; Chwastowski, J. J.; Chytka, L.; Ciftci, A. K.; Cinca, D.; Cindro, V.; Cioara, I. A.; Ciocca, C.; Ciocio, A.; Cirotto, F.; Citron, Z. H.; Citterio, M.; Ciubancan, M.; Clark, A.; Clark, B. L.; Clark, M. R.; Clark, P. J.; Clarke, R. N.; Clement, C.; Coadou, Y.; Cobal, M.; Coccaro, A.; Cochran, J.; Colasurdo, L.; Cole, B.; Colijn, A. P.; Collot, J.; Colombo, T.; Conde Muiño, P.; Coniavitis, E.; Connell, S. H.; Connelly, I. A.; Consorti, V.; Constantinescu, S.; Conti, G.; Conventi, F.; Cooke, M.; Cooper, B. D.; Cooper-Sarkar, A. M.; Cormier, F.; Cormier, K. J. R.; Cornelissen, T.; Corradi, M.; Corriveau, F.; Cortes-Gonzalez, A.; Cortiana, G.; Costa, G.; Costa, M. J.; Costanzo, D.; Cottin, G.; Cowan, G.; Cox, B. E.; Cranmer, K.; Crawley, S. J.; Creager, R. A.; Cree, G.; Crépé-Renaudin, S.; Crescioli, F.; Cribbs, W. A.; Crispin Ortuzar, M.; Cristinziani, M.; Croft, V.; Crosetti, G.; Cueto, A.; Cuhadar Donszelmann, T.; Cummings, J.; Curatolo, M.; Cúth, J.; Czirr, H.; Czodrowski, P.; D'Amen, G.; D'Auria, S.; D'Onofrio, M.; da Cunha Sargedas de Sousa, M. J.; da Via, C.; Dabrowski, W.; Dado, T.; Dai, T.; Dale, O.; Dallaire, F.; Dallapiccola, C.; Dam, M.; Dandoy, J. R.; Dang, N. P.; Daniells, A. C.; Dann, N. S.; Danninger, M.; Dano Hoffmann, M.; Dao, V.; Darbo, G.; Darmora, S.; Dassoulas, J.; Dattagupta, A.; Daubney, T.; Davey, W.; David, C.; Davidek, T.; Davies, M.; Davison, P.; Dawe, E.; Dawson, I.; de, K.; de Asmundis, R.; de Benedetti, A.; de Castro, S.; de Cecco, S.; de Groot, N.; de Jong, P.; de la Torre, H.; de Lorenzi, F.; de Maria, A.; de Pedis, D.; de Salvo, A.; de Sanctis, U.; de Santo, A.; de Vasconcelos Corga, K.; de Vivie de Regie, J. B.; Dearnaley, W. J.; Debbe, R.; Debenedetti, C.; Dedovich, D. V.; Dehghanian, N.; Deigaard, I.; Del Gaudio, M.; Del Peso, J.; Del Prete, T.; Delgove, D.; Deliot, F.; Delitzsch, C. M.; Dell'Acqua, A.; Dell'Asta, L.; Dell'Orso, M.; Della Pietra, M.; Della Volpe, D.; Delmastro, M.; Delporte, C.; Delsart, P. A.; Demarco, D. A.; Demers, S.; Demichev, M.; Demilly, A.; Denisov, S. P.; Denysiuk, D.; Derendarz, D.; Derkaoui, J. E.; Derue, F.; Dervan, P.; Desch, K.; Deterre, C.; Dette, K.; Deviveiros, P. O.; Dewhurst, A.; Dhaliwal, S.; di Ciaccio, A.; di Ciaccio, L.; di Clemente, W. K.; di Donato, C.; di Girolamo, A.; di Girolamo, B.; di Micco, B.; di Nardo, R.; di Petrillo, K. F.; di Simone, A.; di Sipio, R.; di Valentino, D.; Diaconu, C.; Diamond, M.; Dias, F. A.; Diaz, M. A.; Diehl, E. B.; Dietrich, J.; Díez Cornell, S.; Dimitrievska, A.; Dingfelder, J.; Dita, P.; Dita, S.; Dittus, F.; Djama, F.; Djobava, T.; Djuvsland, J. I.; Do Vale, M. A. B.; Dobos, D.; Dobre, M.; Doglioni, C.; Dolejsi, J.; Dolezal, Z.; Donadelli, M.; Donati, S.; Dondero, P.; Donini, J.; Dopke, J.; Doria, A.; Dova, M. T.; Doyle, A. T.; Drechsler, E.; Dris, M.; Du, Y.; Duarte-Campderros, J.; Duchovni, E.; Duckeck, G.; Ducourthial, A.; Ducu, O. A.; Duda, D.; Dudarev, A.; Dudder, A. Chr.; Duffield, E. M.; Duflot, L.; Dührssen, M.; Dumancic, M.; Dumitriu, A. E.; Duncan, A. K.; Dunford, M.; Duran Yildiz, H.; Düren, M.; Durglishvili, A.; Duschinger, D.; Dutta, B.; Dyndal, M.; Eckardt, C.; Ecker, K. M.; Edgar, R. C.; Eifert, T.; Eigen, G.; Einsweiler, K.; Ekelof, T.; El Kacimi, M.; El Kosseifi, R.; Ellajosyula, V.; Ellert, M.; Elles, S.; Ellinghaus, F.; Elliot, A. A.; Ellis, N.; Elmsheuser, J.; Elsing, M.; Emeliyanov, D.; Enari, Y.; Endner, O. C.; Ennis, J. S.; Erdmann, J.; Ereditato, A.; Ernis, G.; Ernst, M.; Errede, S.; Ertel, E.; Escalier, M.; Esch, H.; Escobar, C.; Esposito, B.; Etienvre, A. I.; Etzion, E.; Evans, H.; Ezhilov, A.; Fabbri, F.; Fabbri, L.; Facini, G.; Fakhrutdinov, R. M.; Falciano, S.; Falla, R. J.; Faltova, J.; Fang, Y.; Fanti, M.; Farbin, A.; Farilla, A.; Farina, C.; Farina, E. M.; Farooque, T.; Farrell, S.; Farrington, S. M.; Farthouat, P.; Fassi, F.; Fassnacht, P.; Fassouliotis, D.; Faucci Giannelli, M.; Favareto, A.; Fawcett, W. J.; Fayard, L.; Fedin, O. L.; Fedorko, W.; Feigl, S.; Feligioni, L.; Feng, C.; Feng, E. J.; Feng, H.; Fenyuk, A. B.; Feremenga, L.; Fernandez Martinez, P.; Fernandez Perez, S.; Ferrando, J.; Ferrari, A.; Ferrari, P.; Ferrari, R.; Ferreira de Lima, D. E.; Ferrer, A.; Ferrere, D.; Ferretti, C.; Fiedler, F.; Filipčič, A.; Filipuzzi, M.; Filthaut, F.; Fincke-Keeler, M.; Finelli, K. D.; Fiolhais, M. C. N.; Fiorini, L.; Fischer, A.; Fischer, C.; Fischer, J.; Fisher, W. C.; Flaschel, N.; Fleck, I.; Fleischmann, P.; Fletcher, R. R. M.; Flick, T.; Flierl, B. M.; Flores Castillo, L. R.; Flowerdew, M. J.; Forcolin, G. T.; Formica, A.; Forti, A.; Foster, A. G.; Fournier, D.; Fox, H.; Fracchia, S.; Francavilla, P.; Franchini, M.; Franchino, S.; Francis, D.; Franconi, L.; Franklin, M.; Frate, M.; Fraternali, M.; Freeborn, D.; Fressard-Batraneanu, S. M.; Freund, B.; Froidevaux, D.; Frost, J. A.; Fukunaga, C.; Fullana Torregrosa, E.; Fusayasu, T.; Fuster, J.; Gabaldon, C.; Gabizon, O.; Gabrielli, A.; Gabrielli, A.; Gach, G. P.; Gadatsch, S.; Gadomski, S.; Gagliardi, G.; Gagnon, L. G.; Gagnon, P.; Galea, C.; Galhardo, B.; Gallas, E. J.; Gallop, B. J.; Gallus, P.; Galster, G.; Gan, K. K.; Ganguly, S.; Gao, J.; Gao, Y.; Gao, Y. S.; Garay Walls, F. M.; García, C.; García Navarro, J. E.; Garcia-Sciveres, M.; Gardner, R. W.; Garelli, N.; Garonne, V.; Gascon Bravo, A.; Gasnikova, K.; Gatti, C.; Gaudiello, A.; Gaudio, G.; Gavrilenko, I. L.; Gay, C.; Gaycken, G.; Gazis, E. N.; Gee, C. N. P.; Geisen, M.; Geisler, M. P.; Gellerstedt, K.; Gemme, C.; Genest, M. H.; Geng, C.; Gentile, S.; Gentsos, C.; George, S.; Gerbaudo, D.; Gershon, A.; Ghasemi, S.; Ghneimat, M.; Giacobbe, B.; Giagu, S.; Giannetti, P.; Gibson, S. M.; Gignac, M.; Gilchriese, M.; Gillberg, D.; Gilles, G.; Gingrich, D. M.; Giokaris, N.; Giordani, M. P.; Giorgi, F. M.; Giraud, P. F.; Giromini, P.; Giugni, D.; Giuli, F.; Giuliani, C.; Giulini, M.; Gjelsten, B. K.; Gkaitatzis, S.; Gkialas, I.; Gkougkousis, E. L.; Gladilin, L. K.; Glasman, C.; Glatzer, J.; Glaysher, P. C. F.; Glazov, A.; Goblirsch-Kolb, M.; Godlewski, J.; Goldfarb, S.; Golling, T.; Golubkov, D.; Gomes, A.; Gonçalo, R.; Goncalves Gama, R.; Goncalves Pinto Firmino da Costa, J.; Gonella, G.; Gonella, L.; Gongadze, A.; González de La Hoz, S.; Gonzalez-Sevilla, S.; Goossens, L.; Gorbounov, P. A.; Gordon, H. A.; Gorelov, I.; Gorini, B.; Gorini, E.; Gorišek, A.; Goshaw, A. T.; Gössling, C.; Gostkin, M. I.; Goudet, C. R.; Goujdami, D.; Goussiou, A. G.; Govender, N.; Gozani, E.; Graber, L.; Grabowska-Bold, I.; Gradin, P. O. J.; Gramling, J.; Gramstad, E.; Grancagnolo, S.; Gratchev, V.; Gravila, P. M.; Gray, H. M.; Greenwood, Z. D.; Grefe, C.; Gregersen, K.; Gregor, I. M.; Grenier, P.; Grevtsov, K.; Griffiths, J.; Grillo, A. A.; Grimm, K.; Grinstein, S.; Gris, Ph.; Grivaz, J.-F.; Groh, S.; Gross, E.; Grosse-Knetter, J.; Grossi, G. C.; Grout, Z. J.; Guan, L.; Guan, W.; Guenther, J.; Guescini, F.; Guest, D.; Gueta, O.; Gui, B.; Guido, E.; Guillemin, T.; Guindon, S.; Gul, U.; Gumpert, C.; Guo, J.; Guo, W.; Guo, Y.; Gupta, R.; Gupta, S.; Gustavino, G.; Gutierrez, P.; Gutierrez Ortiz, N. G.; Gutschow, C.; Guyot, C.; Guzik, M. P.; Gwenlan, C.; Gwilliam, C. B.; Haas, A.; Haber, C.; Hadavand, H. K.; Hadef, A.; Hageböck, S.; Hagihara, M.; Hakobyan, H.; Haleem, M.; Haley, J.; Halladjian, G.; Hallewell, G. D.; Hamacher, K.; Hamal, P.; Hamano, K.; Hamilton, A.; Hamity, G. N.; Hamnett, P. G.; Han, L.; Han, S.; Hanagaki, K.; Hanawa, K.; Hance, M.; Haney, B.; Hanke, P.; Hansen, J. B.; Hansen, J. D.; Hansen, M. C.; Hansen, P. H.; Hara, K.; Hard, A. S.; Harenberg, T.; Hariri, F.; Harkusha, S.; Harrington, R. D.; Harrison, P. F.; Hartjes, F.; Hartmann, N. M.; Hasegawa, M.; Hasegawa, Y.; Hasib, A.; Hassani, S.; Haug, S.; Hauser, R.; Hauswald, L.; Havener, L. B.; Havranek, M.; Hawkes, C. M.; Hawkings, R. J.; Hayakawa, D.; Hayden, D.; Hays, C. P.; Hays, J. M.; Hayward, H. S.; Haywood, S. J.; Head, S. J.; Heck, T.; Hedberg, V.; Heelan, L.; Heidegger, K. K.; Heim, S.; Heim, T.; Heinemann, B.; Heinrich, J. J.; Heinrich, L.; Heinz, C.; Hejbal, J.; Helary, L.; Held, A.; Hellman, S.; Helsens, C.; Henderson, J.; Henderson, R. C. W.; Heng, Y.; Henkelmann, S.; Correia, A. M. Henriques; Henrot-Versille, S.; Herbert, G. H.; Herde, H.; Herget, V.; Hernández Jiménez, Y.; Herten, G.; Hertenberger, R.; Hervas, L.; Herwig, T. C.; Hesketh, G. G.; Hessey, N. P.; Hetherly, J. W.; Higashino, S.; Higón-Rodriguez, E.; Hill, E.; Hill, J. C.; Hiller, K. H.; Hillier, S. J.; Hinchliffe, I.; Hirose, M.; Hirschbuehl, D.; Hiti, B.; Hladik, O.; Hoad, X.; Hobbs, J.; Hod, N.; Hodgkinson, M. C.; Hodgson, P.; Hoecker, A.; Hoeferkamp, M. R.; Hoenig, F.; Hohn, D.; Holmes, T. R.; Homann, M.; Honda, S.; Honda, T.; Hong, T. M.; Hooberman, B. H.; Hopkins, W. H.; Horii, Y.; Horton, A. J.; Hostachy, J.-Y.; Hou, S.; Hoummada, A.; Howarth, J.; Hoya, J.; Hrabovsky, M.; Hristova, I.; Hrivnac, J.; Hryn'Ova, T.; Hrynevich, A.; Hsu, P. J.; Hsu, S.-C.; Hu, Q.; Hu, S.; Huang, Y.; Hubacek, Z.; Hubaut, F.; Huegging, F.; Huffman, T. B.; Hughes, E. W.; Hughes, G.; Huhtinen, M.; Huo, P.; Huseynov, N.; Huston, J.; Huth, J.; Iacobucci, G.; Iakovidis, G.; Ibragimov, I.; Iconomidou-Fayard, L.; Iengo, P.; Igonkina, O.; Iizawa, T.; Ikegami, Y.; Ikeno, M.; Ilchenko, Y.; Iliadis, D.; Ilic, N.; Introzzi, G.; Ioannou, P.; Iodice, M.; Iordanidou, K.; Ippolito, V.; Ishijima, N.; Ishino, M.; Ishitsuka, M.; Issever, C.; Istin, S.; Ito, F.; Iturbe Ponce, J. M.; Iuppa, R.; Iwasaki, H.; Izen, J. M.; Izzo, V.; Jabbar, S.; Jackson, P.; Jain, V.; Jakobi, K. B.; Jakobs, K.; Jakobsen, S.; Jakoubek, T.; Jamin, D. O.; Jana, D. K.; Jansky, R.; Janssen, J.; Janus, M.; Janus, P. A.; Jarlskog, G.; Javadov, N.; Javůrek, T.; Javurkova, M.; Jeanneau, F.; Jeanty, L.; Jejelava, J.; Jelinskas, A.; Jenni, P.; Jeske, C.; Jézéquel, S.; Ji, H.; Jia, J.; Jiang, H.; Jiang, Y.; Jiang, Z.; Jiggins, S.; Jimenez Pena, J.; Jin, S.; Jinaru, A.; Jinnouchi, O.; Jivan, H.; Johansson, P.; Johns, K. A.; Johnson, C. A.; Johnson, W. J.; Jon-And, K.; Jones, R. W. L.; Jones, S.; Jones, T. J.; Jongmanns, J.; Jorge, P. M.; Jovicevic, J.; Ju, X.; Juste Rozas, A.; Köhler, M. K.; Kaczmarska, A.; Kado, M.; Kagan, H.; Kagan, M.; Kahn, S. J.; Kaji, T.; Kajomovitz, E.; Kalderon, C. W.; Kaluza, A.; Kama, S.; Kamenshchikov, A.; Kanaya, N.; Kaneti, S.; Kanjir, L.; Kantserov, V. A.; Kanzaki, J.; Kaplan, B.; Kaplan, L. S.; Kar, D.; Karakostas, K.; Karastathis, N.; Kareem, M. J.; Karentzos, E.; Karpov, S. N.; Karpova, Z. M.; Karthik, K.; Kartvelishvili, V.; Karyukhin, A. N.; Kasahara, K.; Kashif, L.; Kass, R. D.; Kastanas, A.; Kataoka, Y.; Kato, C.; Katre, A.; Katzy, J.; Kawade, K.; Kawagoe, K.; Kawamoto, T.; Kawamura, G.; Kay, E. F.; Kazanin, V. F.; Keeler, R.; Kehoe, R.; Keller, J. S.; Kempster, J. J.; Keoshkerian; Kepka, O.; Kerševan, B. P.; Kersten, S.; Keyes, R. A.; Khader, M.; Khalil-Zada, F.; Khanov, A.; Kharlamov, A. G.; Kharlamova, T.; Khodinov, A.; Khoo, T. J.; Khovanskiy, V.; Khramov, E.; Khubua, J.; Kido, S.; Kilby, C. R.; Kim, H. Y.; Kim, S. H.; Kim, Y. K.; Kimura, N.; Kind, O. M.; King, B. T.; Kirchmeier, D.; Kirk, J.; Kiryunin, A. E.; Kishimoto, T.; Kisielewska, D.; Kiuchi, K.; Kivernyk, O.; Kladiva, E.; Klapdor-Kleingrothaus, T.; Klein, M. H.; Klein, M.; Klein, U.; Kleinknecht, K.; Klimek, P.; Klimentov, A.; Klingenberg, R.; Klingl, T.; Klioutchnikova, T.; Kluge, E.-E.; Kluit, P.; Kluth, S.; Knapik, J.; Kneringer, E.; Knoops, E. B. F. G.; Knue, A.; Kobayashi, A.; Kobayashi, D.; Kobayashi, T.; Kobel, M.; Kocian, M.; Kodys, P.; Koffas, T.; Koffeman, E.; Köhler, N. M.; Koi, T.; Kolb, M.; Koletsou, I.; Komar, A. A.; Komori, Y.; Kondo, T.; Kondrashova, N.; Köneke, K.; König, A. C.; Kono, T.; Konoplich, R.; Konstantinidis, N.; Kopeliansky, R.; Koperny, S.; Kopp, A. K.; Korcyl, K.; Kordas, K.; Korn, A.; Korol, A. A.; Korolkov, I.; Korolkova, E. V.; Kortner, O.; Kortner, S.; Kosek, T.; Kostyukhin, V. V.; Kotwal, A.; Koulouris, A.; Kourkoumeli-Charalampidi, A.; Kourkoumelis, C.; Kourlitis, E.; Kouskoura, V.; Kowalewska, A. B.; Kowalewski, R.; Kowalski, T. Z.; Kozakai, C.; Kozanecki, W.; Kozhin, A. S.; Kramarenko, V. A.; Kramberger, G.; Krasnopevtsev, D.; Krasznahorkay, A.; Krauss, D.; Kravchenko, A.; Kremer, J. A.; Kretz, M.; Kretzschmar, J.; Kreutzfeldt, K.; Krieger, P.; Krizka, K.; Kroeninger, K.; Kroha, H.; Kroll, J.; Kroseberg, J.; Krstic, J.; Kruchonak, U.; Krüger, H.; Krumnack, N.; Kruse, M. C.; Kruskal, M.; Kubota, T.; Kucuk, H.; Kuday, S.; Kuechler, J. T.; Kuehn, S.; Kugel, A.; Kuger, F.; Kuhl, T.; Kukhtin, V.; Kukla, R.; Kulchitsky, Y.; Kuleshov, S.; Kulinich, Y. P.; Kuna, M.; Kunigo, T.; Kupco, A.; Kuprash, O.; Kurashige, H.; Kurchaninov, L. L.; Kurochkin, Y. A.; Kurth, M. G.; Kus, V.; Kuwertz, E. S.; Kuze, M.; Kvita, J.; Kwan, T.; Kyriazopoulos, D.; La Rosa, A.; La Rosa Navarro, J. L.; La Rotonda, L.; Lacasta, C.; Lacava, F.; Lacey, J.; Lacker, H.; Lacour, D.; Ladygin, E.; Lafaye, R.; Laforge, B.; Lagouri, T.; Lai, S.; Lammers, S.; Lampl, W.; Lançon, E.; Landgraf, U.; Landon, M. P. J.; Lanfermann, M. C.; Lang, V. S.; Lange, J. C.; Lankford, A. J.; Lanni, F.; Lantzsch, K.; Lanza, A.; Lapertosa, A.; Laplace, S.; Laporte, J. F.; Lari, T.; Lasagni Manghi, F.; Lassnig, M.; Laurelli, P.; Lavrijsen, W.; Law, A. T.; Laycock, P.; Lazovich, T.; Lazzaroni, M.; Le, B.; Le Dortz, O.; Le Guirriec, E.; Le Quilleuc, E. P.; Leblanc, M.; Lecompte, T.; Ledroit-Guillon, F.; Lee, C. A.; Lee, S. C.; Lee, L.; Lefebvre, B.; Lefebvre, G.; Lefebvre, M.; Legger, F.; Leggett, C.; Lehan, A.; Lehmann Miotto, G.; Lei, X.; Leight, W. A.; Leite, M. A. L.; Leitner, R.; Lellouch, D.; Lemmer, B.; Leney, K. J. C.; Lenz, T.; Lenzi, B.; Leone, R.; Leone, S.; Leonidopoulos, C.; Lerner, G.; Leroy, C.; Lesage, A. A. J.; Lester, C. G.; Levchenko, M.; Levêque, J.; Levin, D.; Levinson, L. J.; Levy, M.; Lewis, D.; Leyton, M.; Li, B.; Li, C.; Li, H.; Li, L.; Li, L.; Li, Q.; Li, S.; Li, X.; Li, Y.; Liang, Z.; Liberti, B.; Liblong, A.; Lie, K.; Liebal, J.; Liebig, W.; Limosani, A.; Lin, S. C.; Lin, T. H.; Lindquist, B. E.; Lionti, A. E.; Lipeles, E.; Lipniacka, A.; Lisovyi, M.; Liss, T. M.; Lister, A.; Litke, A. M.; Liu, B.; Liu, H.; Liu, H.; Liu, J.; Liu, J. B.; Liu, K.; Liu, L.; Liu, M.; Liu, Y. L.; Liu, Y.; Livan, M.; Lleres, A.; Llorente Merino, J.; Lloyd, S. L.; Lo, C. Y.; Lo Sterzo, F.; Lobodzinska, E. M.; Loch, P.; Loebinger, F. K.; Loew, K. M.; Loginov, A.; Lohse, T.; Lohwasser, K.; Lokajicek, M.; Long, B. A.; Long, J. D.; Long, R. E.; Longo, L.; Looper, K. A.; Lopez, J. A.; Lopez Mateos, D.; Lopez Paz, I.; Lopez Solis, A.; Lorenz, J.; Lorenzo Martinez, N.; Losada, M.; Lösel, P. J.; Lou, X.; Lounis, A.; Love, J.; Love, P. A.; Lu, H.; Lu, N.; Lu, Y. J.; Lubatti, H. J.; Luci, C.; Lucotte, A.; Luedtke, C.; Luehring, F.; Lukas, W.; Luminari, L.; Lundberg, O.; Lund-Jensen, B.; Luzi, P. M.; Lynn, D.; Lysak, R.; Lytken, E.; Lyubushkin, V.; Ma, H.; Ma, L. L.; Ma, Y.; Maccarrone, G.; Macchiolo, A.; MacDonald, C. M.; Maček, B.; Machado Miguens, J.; Madaffari, D.; Madar, R.; Maddocks, H. J.; Mader, W. F.; Madsen, A.; Maeda, J.; Maeland, S.; Maeno, T.; Maevskiy, A.; Magradze, E.; Mahlstedt, J.; Maiani, C.; Maidantchik, C.; Maier, A. A.; Maier, T.; Maio, A.; Majewski, S.; Makida, Y.; Makovec, N.; Malaescu, B.; Malecki, Pa.; Maleev, V. P.; Malek, F.; Mallik, U.; Malon, D.; Malone, C.; Maltezos, S.; Malyukov, S.; Mamuzic, J.; Mancini, G.; Mandelli, L.; Mandić, I.; Maneira, J.; Manhaes de Andrade Filho, L.; Manjarres Ramos, J.; Mann, A.; Manousos, A.; Mansoulie, B.; Mansour, J. D.; Mantifel, R.; Mantoani, M.; Manzoni, S.; Mapelli, L.; Marceca, G.; March, L.; Marchiori, G.; Marcisovsky, M.; Marjanovic, M.; Marley, D. E.; Marroquim, F.; Marsden, S. P.; Marshall, Z.; Martensson, M. U. F.; Marti-Garcia, S.; Martin, C. B.; Martin, T. A.; Martin, V. J.; Martin Dit Latour, B.; Martinez, M.; Martinez Outschoorn, V. I.; Martin-Haugh, S.; Martoiu, V. S.; Martyniuk, A. C.; Marzin, A.; Masetti, L.; Mashimo, T.; Mashinistov, R.; Masik, J.; Maslennikov, A. L.; Massa, L.; Mastrandrea, P.; Mastroberardino, A.; Masubuchi, T.; Mättig, P.; Maurer, J.; Maxfield, S. J.; Maximov, D. A.; Mazini, R.; Maznas, I.; Mazza, S. M.; Mc Fadden, N. C.; McGoldrick, G.; McKee, S. P.; McCarn, A.; McCarthy, R. L.; McCarthy, T. G.; McClymont, L. I.; McDonald, E. F.; McFayden, J. A.; McHedlidze, G.; McMahon, S. J.; McNamara, P. C.; McPherson, R. A.; Meehan, S.; Megy, T. J.; Mehlhase, S.; Mehta, A.; Meideck, T.; Meier, K.; Meineck, C.; Meirose, B.; Melini, D.; Mellado Garcia, B. R.; Melo, M.; Meloni, F.; Menary, S. B.; Meng, L.; Meng, X. T.; Mengarelli, A.; Menke, S.; Meoni, E.; Mergelmeyer, S.; Mermod, P.; Merola, L.; Meroni, C.; Merritt, F. S.; Messina, A.; Metcalfe, J.; Mete, A. S.; Meyer, C.; Meyer, J.-P.; Meyer, J.; Meyer Zu Theenhausen, H.; Miano, F.; Middleton, R. P.; Miglioranzi, S.; Mijović, L.; Mikenberg, G.; Mikestikova, M.; Mikuž, M.; Milesi, M.; Milic, A.; Miller, D. W.; Mills, C.; Milov, A.; Milstead, D. A.; Minaenko, A. A.; Minami, Y.; Minashvili, I. A.; Mincer, A. I.; Mindur, B.; Mineev, M.; Minegishi, Y.; Ming, Y.; Mir, L. M.; Mistry, K. P.; Mitani, T.; Mitrevski, J.; Mitsou, V. A.; Miucci, A.; Miyagawa, P. S.; Mizukami, A.; Mjörnmark, J. U.; Mlynarikova, M.; Moa, T.; Mochizuki, K.; Mogg, P.; Mohapatra, S.; Molander, S.; Moles-Valls, R.; Monden, R.; Mondragon, M. C.; Mönig, K.; Monk, J.; Monnier, E.; Montalbano, A.; Montejo Berlingen, J.; Monticelli, F.; Monzani, S.; Moore, R. W.; Morange, N.; Moreno, D.; Moreno Llácer, M.; Morettini, P.; Morgenstern, S.; Mori, D.; Mori, T.; Morii, M.; Morinaga, M.; Morisbak, V.; Morley, A. K.; Mornacchi, G.; Morris, J. D.; Morvaj, L.; Moschovakos, P.; Mosidze, M.; Moss, H. J.; Moss, J.; Motohashi, K.; Mount, R.; Mountricha, E.; Moyse, E. J. W.; Muanza, S.; Mudd, R. D.; Mueller, F.; Mueller, J.; Mueller, R. S. P.; Muenstermann, D.; Mullen, P.; Mullier, G. A.; Munoz Sanchez, F. J.; Murray, W. J.; Musheghyan, H.; Muškinja, M.; Myagkov, A. G.; Myska, M.; Nachman, B. P.; Nackenhorst, O.; Nagai, K.; Nagai, R.; Nagano, K.; Nagasaka, Y.; Nagata, K.; Nagel, M.; Nagy, E.; Nairz, A. M.; Nakahama, Y.; Nakamura, K.; Nakamura, T.; Nakano, I.; Naranjo Garcia, R. F.; Narayan, R.; Narrias Villar, D. I.; Naryshkin, I.; Naumann, T.; Navarro, G.; Nayyar, R.; Neal, H. A.; Nechaeva, P. Yu.; Neep, T. J.; Negri, A.; Negrini, M.; Nektarijevic, S.; Nellist, C.; Nelson, A.; Nelson, M. E.; Nemecek, S.; Nemethy, P.; Nepomuceno, A. A.; Nessi, M.; Neubauer, M. S.; Neumann, M.; Neves, R. M.; Newman, P. R.; Ng, T. Y.; Nguyen Manh, T.; Nickerson, R. B.; Nicolaidou, R.; Nielsen, J.; Nikolaenko, V.; Nikolic-Audit, I.; Nikolopoulos, K.; Nilsen, J. K.; Nilsson, P.; Ninomiya, Y.; Nisati, A.; Nishu, N.; Nisius, R.; Nobe, T.; Noguchi, Y.; Nomachi, M.; Nomidis, I.; Nomura, M. A.; Nooney, T.; Nordberg, M.; Norjoharuddeen, N.; Novgorodova, O.; Nowak, S.; Nozaki, M.; Nozka, L.; Ntekas, K.; Nurse, E.; Nuti, F.; O'Neil, D. C.; O'Rourke, A. A.; O'Shea, V.; Oakham, F. G.; Oberlack, H.; Obermann, T.; Ocariz, J.; Ochi, A.; Ochoa, I.; Ochoa-Ricoux, J. P.; Oda, S.; Odaka, S.; Ogren, H.; Oh, A.; Oh, S. H.; Ohm, C. C.; Ohman, H.; Oide, H.; Okawa, H.; Okumura, Y.; Okuyama, T.; Olariu, A.; Oleiro Seabra, L. F.; Olivares Pino, S. A.; Oliveira Damazio, D.; Olszewski, A.; Olszowska, J.; Onofre, A.; Onogi, K.; Onyisi, P. U. E.; Oreglia, M. J.; Oren, Y.; Orestano, D.; Orlando, N.; Orr, R. S.; Osculati, B.; Ospanov, R.; Otero Y Garzon, G.; Otono, H.; Ouchrif, M.; Ould-Saada, F.; Ouraou, A.; Oussoren, K. P.; Ouyang, Q.; Owen, M.; Owen, R. E.; Ozcan, V. E.; Ozturk, N.; Pachal, K.; Pacheco Pages, A.; Pacheco Rodriguez, L.; Padilla Aranda, C.; Pagan Griso, S.; Paganini, M.; Paige, F.; Pais, P.; Palacino, G.; Palazzo, S.; Palestini, S.; Palka, M.; Pallin, D.; Panagiotopoulou, E. St.; Panagoulias, I.; Pandini, C. E.; Panduro Vazquez, J. G.; Pani, P.; Panitkin, S.; Pantea, D.; Paolozzi, L.; Papadopoulou, Th. D.; Papageorgiou, K.; Paramonov, A.; Paredes Hernandez, D.; Parker, A. J.; Parker, M. A.; Parker, K. A.; Parodi, F.; Parsons, J. A.; Parzefall, U.; Pascuzzi, V. R.; Pasner, J. M.; Pasqualucci, E.; Passaggio, S.; Pastore, Fr.; Pataraia, S.; Pater, J. R.; Pauly, T.; Pearce, J.; Pearson, B.; Pedersen, L. E.; Pedraza Lopez, S.; Pedro, R.; Peleganchuk, S. V.; Penc, O.; Peng, C.; Peng, H.; Penwell, J.; Peralva, B. S.; Perego, M. M.; Perepelitsa, D. V.; Perini, L.; Pernegger, H.; Perrella, S.; Peschke, R.; Peshekhonov, V. D.; Peters, K.; Peters, R. F. Y.; Petersen, B. A.; Petersen, T. C.; Petit, E.; Petridis, A.; Petridou, C.; Petroff, P.; Petrolo, E.; Petrov, M.; Petrucci, F.; Pettersson, N. E.; Peyaud, A.; Pezoa, R.; Phillips, P. W.; Piacquadio, G.; Pianori, E.; Picazio, A.; Piccaro, E.; Pickering, M. A.; Piegaia, R.; Pilcher, J. E.; Pilkington, A. D.; Pin, A. W. J.; Pinamonti, M.; Pinfold, J. L.; Pirumov, H.; Pitt, M.; Plazak, L.; Pleier, M.-A.; Pleskot, V.; Plotnikova, E.; Pluth, D.; Podberezko, P.; Poettgen, R.; Poggioli, L.; Pohl, D.; Polesello, G.; Poley, A.; Policicchio, A.; Polifka, R.; Polini, A.; Pollard, C. S.; Polychronakos, V.; Pommès, K.; Ponomarenko, D.; Pontecorvo, L.; Pope, B. G.; Popeneciu, G. A.; Poppleton, A.; Pospisil, S.; Potamianos, K.; Potrap, I. N.; Potter, C. J.; Potter, C. T.; Poulard, G.; Poveda, J.; Pozo Astigarraga, M. E.; Pralavorio, P.; Pranko, A.; Prell, S.; Price, D.; Price, L. E.; Primavera, M.; Prince, S.; Proklova, N.; Prokofiev, K.; Prokoshin, F.; Protopopescu, S.; Proudfoot, J.; Przybycien, M.; Puddu, D.; Puri, A.; Puzo, P.; Qian, J.; Qin, G.; Qin, Y.; Quadt, A.; Quayle, W. B.; Queitsch-Maitland, M.; Quilty, D.; Raddum, S.; Radeka, V.; Radescu, V.; Radhakrishnan, S. K.; Radloff, P.; Rados, P.; Ragusa, F.; Rahal, G.; Raine, J. A.; Rajagopalan, S.; Rangel-Smith, C.; Ratti, M. G.; Rauch, D. M.; Rauscher, F.; Rave, S.; Ravenscroft, T.; Ravinovich, I.; Rawling, J. H.; Raymond, M.; Read, A. L.; Readioff, N. P.; Reale, M.; Rebuzzi, D. M.; Redelbach, A.; Redlinger, G.; Reece, R.; Reed, R. G.; Reeves, K.; Rehnisch, L.; Reichert, J.; Reiss, A.; Rembser, C.; Ren, H.; Rescigno, M.; Resconi, S.; Resseguie, E. D.; Rettie, S.; Reynolds, E.; Rezanova, O. L.; Reznicek, P.; Rezvani, R.; Richter, R.; Richter, S.; Richter-Was, E.; Ricken, O.; Ridel, M.; Rieck, P.; Riegel, C. J.; Rieger, J.; Rifki, O.; Rijssenbeek, M.; Rimoldi, A.; Rimoldi, M.; Rinaldi, L.; Ristić, B.; Ritsch, E.; Riu, I.; Rizatdinova, F.; Rizvi, E.; Rizzi, C.; Roberts, R. T.; Robertson, S. H.; Robichaud-Veronneau, A.; Robinson, D.; Robinson, J. E. M.; Robson, A.; Roda, C.; Rodina, Y.; Rodriguez Perez, A.; Rodriguez Rodriguez, D.; Roe, S.; Rogan, C. S.; Røhne, O.; Roloff, J.; Romaniouk, A.; Romano, M.; Romano Saez, S. M.; Romero Adam, E.; Rompotis, N.; Ronzani, M.; Roos, L.; Rosati, S.; Rosbach, K.; Rose, P.; Rosien, N.-A.; Rossetti, V.; Rossi, E.; Rossi, L. P.; Rosten, J. H. N.; Rosten, R.; Rotaru, M.; Roth, I.; Rothberg, J.; Rousseau, D.; Rozanov, A.; Rozen, Y.; Ruan, X.; Rubbo, F.; Rühr, F.; Ruiz-Martinez, A.; Rurikova, Z.; Rusakovich, N. A.; Ruschke, A.; Russell, H. L.; Rutherfoord, J. P.; Ruthmann, N.; Ryabov, Y. F.; Rybar, M.; Rybkin, G.; Ryu, S.; Ryzhov, A.; Rzehorz, G. F.; Saavedra, A. F.; Sabato, G.; Sacerdoti, S.; Sadrozinski, H. F.-W.; Sadykov, R.; Safai Tehrani, F.; Saha, P.; Sahinsoy, M.; Saimpert, M.; Saito, M.; Saito, T.; Sakamoto, H.; Sakurai, Y.; Salamanna, G.; Salazar Loyola, J. E.; Salek, D.; Sales de Bruin, P. H.; Salihagic, D.; Salnikov, A.; Salt, J.; Salvatore, D.; Salvatore, F.; Salvucci, A.; Salzburger, A.; Sammel, D.; Sampsonidis, D.; Sánchez, J.; Sanchez Martinez, V.; Sanchez Pineda, A.; Sandaker, H.; Sandbach, R. L.; Sander, C. O.; Sandhoff, M.; Sandoval, C.; Sankey, D. P. C.; Sannino, M.; Sansoni, A.; Santoni, C.; Santonico, R.; Santos, H.; Santoyo Castillo, I.; Sapp, K.; Sapronov, A.; Saraiva, J. G.; Sarrazin, B.; Sasaki, O.; Sato, K.; Sauvan, E.; Savage, G.; Savard, P.; Savic, N.; Sawyer, C.; Sawyer, L.; Saxon, J.; Sbarra, C.; Sbrizzi, A.; Scanlon, T.; Scannicchio, D. A.; Scarcella, M.; Scarfone, V.; Schaarschmidt, J.; Schacht, P.; Schachtner, B. M.; Schaefer, D.; Schaefer, L.; Schaefer, R.; Schaeffer, J.; Schaepe, S.; Schaetzel, S.; Schäfer, U.; Schaffer, A. C.; Schaile, D.; Schamberger, R. D.; Scharf, V.; Schegelsky, V. A.; Scheirich, D.; Schernau, M.; Schiavi, C.; Schier, S.; Schildgen, L. K.; Schillo, C.; Schioppa, M.; Schlenker, S.; Schmidt-Sommerfeld, K. R.; Schmieden, K.; Schmitt, C.; Schmitt, S.; Schmitz, S.; Schnoor, U.; Schoeffel, L.; Schoening, A.; Schoenrock, B. D.; Schopf, E.; Schott, M.; Schouwenberg, J. F. P.; Schovancova, J.; Schramm, S.; Schuh, N.; Schulte, A.; Schultens, M. J.; Schultz-Coulon, H.-C.; Schulz, H.; Schumacher, M.; Schumm, B. A.; Schune, Ph.; Schwartzman, A.; Schwarz, T. A.; Schweiger, H.; Schwemling, Ph.; Schwienhorst, R.; Schwindling, J.; Schwindt, T.; Sciandra, A.; Sciolla, G.; Scuri, F.; Scutti, F.; Searcy, J.; Seema, P.; Seidel, S. C.; Seiden, A.; Seixas, J. M.; Sekhniaidze, G.; Sekhon, K.; Sekula, S. J.; Semprini-Cesari, N.; Serfon, C.; Serin, L.; Serkin, L.; Sessa, M.; Seuster, R.; Severini, H.; Sfiligoj, T.; Sforza, F.; Sfyrla, A.; Shabalina, E.; Shaikh, N. W.; Shan, L. Y.; Shang, R.; Shank, J. T.; Shapiro, M.; Shatalov, P. B.; Shaw, K.; Shaw, S. M.; Shcherbakova, A.; Shehu, C. Y.; Shen, Y.; Sherwood, P.; Shi, L.; Shimizu, S.; Shimmin, C. O.; Shimojima, M.; Shirabe, S.; Shiyakova, M.; Shlomi, J.; Shmeleva, A.; Shoaleh Saadi, D.; Shochet, M. J.; Shojaii, S.; Shope, D. R.; Shrestha, S.; Shulga, E.; Shupe, M. A.; Sicho, P.; Sickles, A. M.; Sidebo, P. E.; Sideras Haddad, E.; Sidiropoulou, O.; Sidorov, D.; Sidoti, A.; Siegert, F.; Sijacki, Dj.; Silva, J.; Silverstein, S. B.; Simak, V.; Simic, Lj.; Simion, S.; Simioni, E.; Simmons, B.; Simon, M.; Sinervo, P.; Sinev, N. B.; Sioli, M.; Siragusa, G.; Siral, I.; Sivoklokov, S. Yu.; Sjölin, J.; Skinner, M. B.; Skubic, P.; Slater, M.; Slavicek, T.; Slawinska, M.; Sliwa, K.; Slovak, R.; Smakhtin, V.; Smart, B. H.; Smiesko, J.; Smirnov, N.; Smirnov, S. Yu.; Smirnov, Y.; Smirnova, L. N.; Smirnova, O.; Smith, J. W.; Smith, M. N. K.; Smith, R. W.; Smizanska, M.; Smolek, K.; Snesarev, A. A.; Snyder, I. M.; Snyder, S.; Sobie, R.; Socher, F.; Soffer, A.; Soh, D. A.; Sokhrannyi, G.; Solans Sanchez, C. A.; Solar, M.; Soldatov, E. Yu.; Soldevila, U.; Solodkov, A. A.; Soloshenko, A.; Solovyanov, O. V.; Solovyev, V.; Sommer, P.; Son, H.; Song, H. Y.; Sopczak, A.; Sorin, V.; Sosa, D.; Sotiropoulou, C. L.; Soualah, R.; Soukharev, A. M.; South, D.; Sowden, B. C.; Spagnolo, S.; Spalla, M.; Spangenberg, M.; Spanò, F.; Sperlich, D.; Spettel, F.; Spieker, T. M.; Spighi, R.; Spigo, G.; Spiller, L. A.; Spousta, M.; St. Denis, R. D.; Stabile, A.; Stamen, R.; Stamm, S.; Stanecka, E.; Stanek, R. W.; Stanescu, C.; Stanitzki, M. M.; Stapnes, S.; Starchenko, E. A.; Stark, G. H.; Stark, J.; Stark, S. H.; Staroba, P.; Starovoitov, P.; Stärz, S.; Staszewski, R.; Steinberg, P.; Stelzer, B.; Stelzer, H. J.; Stelzer-Chilton, O.; Stenzel, H.; Stewart, G. A.; Stillings, J. A.; Stockton, M. C.; Stoebe, M.; Stoicea, G.; Stolte, P.; Stonjek, S.; Stradling, A. R.; Straessner, A.; Stramaglia, M. E.; Strandberg, J.; Strandberg, S.; Strandlie, A.; Strauss, M.; Strizenec, P.; Ströhmer, R.; Strom, D. M.; Stroynowski, R.; Strubig, A.; Stucci, S. A.; Stugu, B.; Styles, N. A.; Su, D.; Su, J.; Suchek, S.; Sugaya, Y.; Suk, M.; Sulin, V. V.; Sultansoy, S.; Sumida, T.; Sun, S.; Sun, X.; Suruliz, K.; Suster, C. J. E.; Sutton, M. R.; Suzuki, S.; Svatos, M.; Swiatlowski, M.; Swift, S. P.; Sydorenko, A.; Sykora, I.; Sykora, T.; Ta, D.; Tackmann, K.; Taenzer, J.; Taffard, A.; Tafirout, R.; Taiblum, N.; Takai, H.; Takashima, R.; Takeshita, T.; Takubo, Y.; Talby, M.; Talyshev, A. A.; Tanaka, J.; Tanaka, M.; Tanaka, R.; Tanaka, S.; Tanioka, R.; Tannenwald, B. B.; Tapia Araya, S.; Tapprogge, S.; Tarem, S.; Tartarelli, G. F.; Tas, P.; Tasevsky, M.; Tashiro, T.; Tassi, E.; Tavares Delgado, A.; Tayalati, Y.; Taylor, A. C.; Taylor, G. N.; Taylor, P. T. E.; Taylor, W.; Teixeira-Dias, P.; Temple, D.; Ten Kate, H.; Teng, P. K.; Teoh, J. J.; Tepel, F.; Terada, S.; Terashi, K.; Terron, J.; Terzo, S.; Testa, M.; Teuscher, R. J.; Theveneaux-Pelzer, T.; Thomas, J. P.; Thomas-Wilsker, J.; Thompson, P. D.; Thompson, A. S.; Thomsen, L. A.; Thomson, E.; Tibbetts, M. J.; Ticse Torres, R. E.; Tikhomirov, V. O.; Tikhonov, Yu. A.; Timoshenko, S.; Tipton, P.; Tisserant, S.; Todome, K.; Todorova-Nova, S.; Tojo, J.; Tokár, S.; Tokushuku, K.; Tolley, E.; Tomlinson, L.; Tomoto, M.; Tompkins, L.; Toms, K.; Tong, B.; Tornambe, P.; Torrence, E.; Torres, H.; Torró Pastor, E.; Toth, J.; Touchard, F.; Tovey, D. R.; Treado, C. J.; Trefzger, T.; Tricoli, A.; Trigger, I. M.; Trincaz-Duvoid, S.; Tripiana, M. F.; Trischuk, W.; Trocmé, B.; Trofymov, A.; Troncon, C.; Trottier-McDonald, M.; Trovatelli, M.; Truong, L.; Trzebinski, M.; Trzupek, A.; Tsang, K. W.; Tseng, J. C.-L.; Tsiareshka, P. V.; Tsipolitis, G.; Tsirintanis, N.; Tsiskaridze, S.; Tsiskaridze, V.; Tskhadadze, E. G.; Tsui, K. M.; Tsukerman, I. I.; Tsulaia, V.; Tsuno, S.; Tsybychev, D.; Tu, Y.; Tudorache, A.; Tudorache, V.; Tulbure, T. T.; Tuna, A. N.; Tupputi, S. A.; Turchikhin, S.; Turgeman, D.; Turk Cakir, I.; Turra, R.; Tuts, P. M.; Ucchielli, G.; Ueda, I.; Ughetto, M.; Ukegawa, F.; Unal, G.; Undrus, A.; Unel, G.; Ungaro, F. C.; Unno, Y.; Unverdorben, C.; Urban, J.; Urquijo, P.; Urrejola, P.; Usai, G.; Usui, J.; Vacavant, L.; Vacek, V.; Vachon, B.; Valderanis, C.; Valdes Santurio, E.; Valencic, N.; Valentinetti, S.; Valero, A.; Valéry, L.; Valkar, S.; Vallier, A.; Valls Ferrer, J. A.; van den Wollenberg, W.; van der Graaf, H.; van Eldik, N.; van Gemmeren, P.; van Nieuwkoop, J.; van Vulpen, I.; van Woerden, M. C.; Vanadia, M.; Vandelli, W.; Vanguri, R.; Vaniachine, A.; Vankov, P.; Vardanyan, G.; Vari, R.; Varnes, E. W.; Varni, C.; Varol, T.; Varouchas, D.; Vartapetian, A.; Varvell, K. E.; Vasquez, J. G.; Vasquez, G. A.; Vazeille, F.; Vazquez Schroeder, T.; Veatch, J.; Veeraraghavan, V.; Veloce, L. M.; Veloso, F.; Veneziano, S.; Ventura, A.; Venturi, M.; Venturi, N.; Venturini, A.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, J. C.; Vetterli, M. C.; Viaux Maira, N.; Viazlo, O.; Vichou, I.; Vickey, T.; Vickey Boeriu, O. E.; Viehhauser, G. H. A.; Viel, S.; Vigani, L.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinogradov, V. B.; Vishwakarma, A.; Vittori, C.; Vivarelli, I.; Vlachos, S.; Vlasak, M.; Vogel, M.; Vokac, P.; Volpi, G.; Volpi, M.; von der Schmitt, H.; von Toerne, E.; Vorobel, V.; Vorobev, K.; Vos, M.; Voss, R.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vuillermet, R.; Vukotic, I.; Wagner, P.; Wagner, W.; Wahlberg, H.; Wahrmund, S.; Wakabayashi, J.; Walder, J.; Walker, R.; Walkowiak, W.; Wallangen, V.; Wang, C.; Wang, C.; Wang, F.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, Q.; Wang, R.; Wang, S. M.; Wang, T.; Wang, W.; Wang, W.; Wang, Z.; Wanotayaroj, C.; Warburton, A.; Ward, C. P.; Wardrope, D. R.; Washbrook, A.; Watkins, P. M.; Watson, A. T.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, B. M.; Webb, A. F.; Webb, S.; Weber, M. S.; Weber, S. W.; Weber, S. A.; Webster, J. S.; Weidberg, A. R.; Weinert, B.; Weingarten, J.; Weiser, C.; Weits, H.; Wells, P. S.; Wenaus, T.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M. D.; Werner, P.; Wessels, M.; Whalen, K.; Whallon, N. L.; Wharton, A. M.; White, A.; White, M. J.; White, R.; Whiteson, D.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wiglesworth, C.; Wiik-Fuchs, L. A. M.; Wildauer, A.; Wilk, F.; Wilkens, H. G.; Williams, H. H.; Williams, S.; Willis, C.; Willocq, S.; Wilson, J. A.; Wingerter-Seez, I.; Winklmeier, F.; Winston, O. J.; Winter, B. T.; Wittgen, M.; Wobisch, M.; Wolf, T. M. H.; Wolff, R.; Wolter, M. W.; Wolters, H.; Worm, S. D.; Wosiek, B. K.; Wotschack, J.; Woudstra, M. J.; Wozniak, K. W.; Wu, M.; Wu, S. L.; Wu, X.; Wu, Y.; Wyatt, T. R.; Wynne, B. M.; Xella, S.; Xi, Z.; Xia, L.; Xu, D.; Xu, L.; Yabsley, B.; Yacoob, S.; Yamaguchi, D.; Yamaguchi, Y.; Yamamoto, A.; Yamamoto, S.; Yamanaka, T.; Yamauchi, K.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, H.; Yang, Y.; Yang, Z.; Yao, W.-M.; Yap, Y. C.; Yasu, Y.; Yatsenko, E.; Yau Wong, K. H.; Ye, J.; Ye, S.; Yeletskikh, I.; Yigitbasi, E.; Yildirim, E.; Yorita, K.; Yoshihara, K.; Young, C.; Young, C. J. S.; Youssef, S.; Yu, D. R.; Yu, J.; Yu, J.; Yuan, L.; Yuen, S. P. Y.; Yusuff, I.; Zabinski, B.; Zacharis, G.; Zaidan, R.; Zaitsev, A. M.; Zakharchuk, N.; Zalieckas, J.; Zaman, A.; Zambito, S.; Zanzi, D.; Zeitnitz, C.; Zeman, M.; Zemla, A.; Zeng, J. C.; Zeng, Q.; Zenin, O.; Ženiš, T.; Zerwas, D.; Zhang, D.; Zhang, F.; Zhang, G.; Zhang, H.; Zhang, J.; Zhang, L.; Zhang, L.; Zhang, M.; Zhang, R.; Zhang, R.; Zhang, X.; Zhang, Y.; Zhang, Z.; Zhao, X.; Zhao, Y.; Zhao, Z.; Zhemchugov, A.; Zhong, J.; Zhou, B.; Zhou, C.; Zhou, L.; Zhou, M.; Zhou, M.; Zhou, N.; Zhu, C. G.; Zhu, H.; Zhu, J.; Zhu, Y.; Zhuang, X.; Zhukov, K.; Zibell, A.; Zieminska, D.; Zimine, N. I.; Zimmermann, C.; Zimmermann, S.; Zinonos, Z.; Zinser, M.; Ziolkowski, M.; Živković, L.; Zobernig, G.; Zoccoli, A.; Zou, R.; Zur Nedden, M.; Zwalinski, L.

2017-09-01

Light-by-light scattering (γγ --> γγ) is a quantum-mechanical process that is forbidden in the classical theory of electrodynamics. This reaction is accessible at the Large Hadron Collider thanks to the large electromagnetic field strengths generated by ultra-relativistic colliding lead ions. Using 480 μb-1 of lead-lead collision data recorded at a centre-of-mass energy per nucleon pair of 5.02 TeV by the ATLAS detector, here we report evidence for light-by-light scattering. A total of 13 candidate events were observed with an expected background of 2.6 +/- 0.7 events. After background subtraction and analysis corrections, the fiducial cross-section of the process Pb + Pb (γγ) --> Pb(*) + Pb(*)γγ, for photon transverse energy ET > 3 GeV, photon absolute pseudorapidity |η| < 2.4, diphoton invariant mass greater than 6 GeV, diphoton transverse momentum lower than 2 GeV and diphoton acoplanarity below 0.01, is measured to be 70 +/- 24 (stat.) +/- 17 (syst.) nb, which is in agreement with the standard model predictions.

Exclusive QCD processes, quark-hadron duality, and the transition to perturbative QCD

NASA Astrophysics Data System (ADS)

Corianò, Claudio; Li, Hsiang-nan; Savkli, Cetin

1998-07-01

Experiments at CEBAF will scan the intermediate-energy region of the QCD dynamics for the nucleon form factors and for Compton Scattering. These experiments will definitely clarify the role of resummed perturbation theory and of quark-hadron duality (QCD sum rules) in this regime. With this perspective in mind, we review the factorization theorem of perturbative QCD for exclusive processes at intermediate energy scales, which embodies the transverse degrees of freedom of a parton and the Sudakov resummation of the corresponding large logarithms. We concentrate on the pion and proton electromagnetic form factors and on pion Compton scattering. New ingredients, such as the evolution of the pion wave function and the complete two-loop expression of the Sudakov factor, are included. The sensitivity of our predictions to the infrared cutoff for the Sudakov evolution is discussed. We also elaborate on QCD sum rule methods for Compton Scattering, which provide an alternative description of this process. We show that, by comparing the local duality analysis to resummed perturbation theory, it is possible to describe the transition of exclusive processes to perturbative QCD.

Near Zone: Basic scattering code user's manual with space station applications

NASA Technical Reports Server (NTRS)

Marhefka, R. J.; Silvestro, J. W.

1989-01-01

The Electromagnetic Code - Basic Scattering Code, Version 3, is a user oriented computer code to analyze near and far zone patterns of antennas in the presence of scattering structures, to provide coupling between antennas in a complex environment, and to determine radiation hazard calculations at UHF and above. The analysis is based on uniform asymptotic techniques formulated in terms of the Uniform Geometrical Theory of Diffraction (UTD). Complicated structures can be simulated by arbitrarily oriented flat plates and an infinite ground plane that can be perfectly conducting or dielectric. Also, perfectly conducting finite elliptic cylinder, elliptic cone frustum sections, and finite composite ellipsoids can be used to model the superstructure of a ship, the body of a truck, and airplane, a satellite, etc. This manual gives special consideration to space station modeling applications. This is a user manual designed to give an overall view of the operation of the computer code, to instruct a user in how to model structures, and to show the validity of the code by comparing various computed results against measured and alternative calculations such as method of moments whenever available.

Time-Domain Computation Of Electromagnetic Fields In MMICs

NASA Technical Reports Server (NTRS)

Lansing, Faiza S.; Rascoe, Daniel L.

1995-01-01

Maxwell's equations solved on three-dimensional, conformed orthogonal grids by finite-difference techniques. Method of computing frequency-dependent electrical parameters of monolithic microwave integrated circuit (MMIC) involves time-domain computation of propagation of electromagnetic field in response to excitation by single pulse at input terminal, followed by computation of Fourier transforms to obtain frequency-domain response from time-domain response. Parameters computed include electric and magnetic fields, voltages, currents, impedances, scattering parameters, and effective dielectric constants. Powerful and efficient means for analyzing performance of even complicated MMIC.

Surface-enhanced Raman scattering from graphene covered gold nanocap arrays

NASA Astrophysics Data System (ADS)

Long, Kailin; Luo, Xiaoguang; Nan, Haiyan; Du, Deyang; Zhao, Weiwei; Ni, Zhenhua; Qiu, Teng

2013-11-01

This work reports an efficient method to fabricate large-area flexible substrates for surface enhanced Raman scattering (SERS) application. Our technique is based on a single-step direct imprint process via porous anodic alumina stamps. Periodic hexagonal arrangements of porous anodic alumina stamps are transferred to the polyethylene terephthalate substrates by mechanically printing process. Printed nanocaps will turn into "hot spots" for electromagnetic enhancement with a deposited gold film by high vacuum evaporation. The gaps between the nanocaps are controllable with a tight correspondence to the thickness of the deposited gold, which dramatically influence the enhancement factor. After covered with a single-layer graphene sheet, the gold nanocap substrate can be further optimized with an extra enhancement of Raman signals, and it is available for the trace detection of probe molecules. This convenient, simple, and low-cost method of making flexible SERS-active substrates potentially opens a way towards biochemical analysis and disease detection.

Electromagnetic polarization-controlled perfect switching effect with high-refractive-index dimers and the beam-splitter configuration

PubMed Central

Barreda, Ángela I.; Saleh, Hassan; Litman, Amelie; González, Francisco; Geffrin, Jean-Michel; Moreno, Fernando

2017-01-01

Sub-wavelength particles made from high-index dielectrics, either individual or as ensembles, are ideal candidates for multifunctional elements in optical devices. Their directionality effects are traditionally analysed through forward and backward measurements, even if these directions are not convenient for in-plane scattering practical purposes. Here we present unambiguous experimental evidence in the microwave range that for a dimer of HRI spherical particles, a perfect switching effect is observed out of those directions as a consequence of the mutual particle electric/magnetic interaction. The binary state depends on the excitation polarization. Its analysis is performed through the linear polarization degree of scattered radiation at a detection direction perpendicular to the incident direction: the beam-splitter configuration. The scaling property of Maxwell's equations allows the generalization of our results to other frequency ranges and dimension scales, for instance, the visible and the nanometric scale. PMID:28051061

Properties of cutoff corrugated surfaces for corrugated horn design. [corrugation shape and density effects on scattering

NASA Technical Reports Server (NTRS)

Mentzer, C. A.; Peters, L., Jr.

1974-01-01

Corrugated horns involve a junction between the corrugated surface and a conducting ground plane. Proper horn design requires an understanding of the electromagnetic properties of the corrugated surface and this junction. An integral equation solution has been used to study the influence of corrugation density and tooth thickness on the power loss, surface current, and the scattering from a ground plane/corrugated surface junction.

COSMIC-RAY PITCH-ANGLE SCATTERING IN IMBALANCED MHD TURBULENCE SIMULATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weidl, Martin S.; Jenko, Frank; Teaca, Bogdan

2015-09-20

Pitch-angle scattering rates for cosmic-ray particles in MHD simulations with imbalanced turbulence are calculated for fully evolving electromagnetic turbulence. We compare with theoretical predictions derived from the quasilinear theory of cosmic-ray diffusion for an idealized slab spectrum and demonstrate how cross helicity affects the shape of the pitch-angle diffusion coefficient. Additional simulations in evolving magnetic fields or static field configurations provide evidence that the scattering anisotropy in imbalanced turbulence is not primarily due to coherence with propagating Alfvén waves, but an effect of the spatial structure of electric fields in cross-helical MHD turbulence.

Scattering of classical and quantum particles by impulsive fields

NASA Astrophysics Data System (ADS)

Balasin, Herbert; Aichelburg, Peter C.

2018-05-01

We investigate the scattering of classical and quantum particles in impulsive backgrounds fields. These fields model short outbursts of radiation propagating with the speed of light. The singular nature of the problem will be accounted for by the use of Colombeau’s generalized function which however give rise to ambiguities. It is the aim of the paper to show that these ambiguities can be overcome by implementing additional physical conditions, which in the non-singular case would be satisfied automatically. As example we discuss the scattering of classical, Klein–Gordon and Dirac particles in impulsive electromagnetic fields.

Vector and Axial Form Factors Applied to Neutrino Quasielastic Scattering

NASA Astrophysics Data System (ADS)

Budd, H.; Bodek, A.; Arrington, J.

2005-02-01

We calculate the quasielastic cross sections for neutrino scattering on nucleons using up to date fits to the nucleon elastic electromagnetic form factors GEp, GEn, GMp, GMn, and weak form factors. We show the extraction of F(q). We show the that F(q) has a different contribution to the anti-neutrino cross section, and how the anti-neutrino data can be used to check F(q) extracted from neutrino scattering. (Presented by Howard Budd at NuInt04, Mar. 2004, Laboratori Nazionali del Gran Sasso - INFN - Assergi, Italy [ http://nuint04.lngs.infn.it/])

Bragg scattering of electromagnetic waves by microwave-produced plasma layers

NASA Technical Reports Server (NTRS)

Kuo, S. P.; Zhang, Y. S.

1990-01-01

A set of parallel plasma layers is generated by two intersecting microwave pulses in a chamber containing dry air at a pressure comparable to the upper atmosphere. The dependencies of breakdown conditions on the pressure and pulse length are examined. The results are shown to be consistent with the appearance of tail erosion of the microwave pulse caused by air breakdown. A Bragg scattering experiment, using the plasma layers as a Bragg reflector, is then performed. Both time domain and frequency domain measurements of wave scattering are conducted. The experimental results are found to agree very well with the theory.

Electromagnetic scattering and radiation from microstrip patch antennas and spirals residing in a cavity

NASA Technical Reports Server (NTRS)

Volakis, J. L.; Gong, J.; Alexanian, A.; Woo, A.

1992-01-01

A new hybrid method is presented for the analysis of the scattering and radiation by conformal antennas and arrays comprised of circular or rectangular elements. In addition, calculations for cavity-backed spiral antennas are given. The method employs a finite element formulation within the cavity and the boundary integral (exact boundary condition) for terminating the mesh. By virtue of the finite element discretization, the method has no restrictions on the geometry and composition of the cavity or its termination. Furthermore, because of the convolutional nature of the boundary integral and the inherent sparseness of the finite element matrix, the storage requirement is kept very low at O(n). These unique features of the method have already been exploited in other scattering applications and have permitted the analysis of large-size structures with remarkable efficiency. In this report, we describe the method's formulation and implementation for circular and rectangular patch antennas in different superstrate and substrate configurations which may also include the presence of lumped loads and resistive sheets/cards. Also, various modelling approaches are investigated and implemented for characterizing a variety of feed structures to permit the computation of the input impedance and radiation pattern. Many computational examples for rectangular and circular patch configurations are presented which demonstrate the method's versatility, modeling capability and accuracy.

EDITORIAL: Introduction to the special issue on electromagnetic inverse problems: emerging methods and novel applications Introduction to the special issue on electromagnetic inverse problems: emerging methods and novel applications

NASA Astrophysics Data System (ADS)

Dorn, O.; Lesselier, D.

2010-07-01

Inverse problems in electromagnetics have a long history and have stimulated exciting research over many decades. New applications and solution methods are still emerging, providing a rich source of challenging topics for further investigation. The purpose of this special issue is to combine descriptions of several such developments that are expected to have the potential to fundamentally fuel new research, and to provide an overview of novel methods and applications for electromagnetic inverse problems. There have been several special sections published in Inverse Problems over the last decade addressing fully, or partly, electromagnetic inverse problems. Examples are: Electromagnetic imaging and inversion of the Earth's subsurface (Guest Editors: D Lesselier and T Habashy) October 2000 Testing inversion algorithms against experimental data (Guest Editors: K Belkebir and M Saillard) December 2001 Electromagnetic and ultrasonic nondestructive evaluation (Guest Editors: D Lesselier and J Bowler) December 2002 Electromagnetic characterization of buried obstacles (Guest Editors: D Lesselier and W C Chew) December 2004 Testing inversion algorithms against experimental data: inhomogeneous targets (Guest Editors: K Belkebir and M Saillard) December 2005 Testing inversion algorithms against experimental data: 3D targets (Guest Editors: A Litman and L Crocco) February 2009 In a certain sense, the current issue can be understood as a continuation of this series of special sections on electromagnetic inverse problems. On the other hand, its focus is intended to be more general than previous ones. Instead of trying to cover a well-defined, somewhat specialized research topic as completely as possible, this issue aims to show the broad range of techniques and applications that are relevant to electromagnetic imaging nowadays, which may serve as a source of inspiration and encouragement for all those entering this active and rapidly developing research area. Also, the construction of this special issue is likely to have been different from preceding ones. In addition to the invitations sent to specific research groups involved in electromagnetic inverse problems, the Guest Editors also solicited recommendations, from a large number of experts, of potential authors who were thereupon encouraged to contribute. Moreover, an open call for contributions was published on the homepage of Inverse Problems in order to attract as wide a scope of contributions as possible. This special issue's attempt at generality might also define its limitations: by no means could this collection of papers be exhaustive or complete, and as Guest Editors we are well aware that many exciting topics and potential contributions will be missing. This, however, also determines its very special flavor: besides addressing electromagnetic inverse problems in a broad sense, there were only a few restrictions on the contributions considered for this section. One requirement was plausible evidence of either novelty or the emergent nature of the technique or application described, judged mainly by the referees, and in some cases by the Guest Editors. The technical quality of the contributions always remained a stringent condition of acceptance, final adjudication (possibly questionable either way, not always positive) being made in most cases once a thorough revision process had been carried out. Therefore, we hope that the final result presented here constitutes an interesting collection of novel ideas and applications, properly refereed and edited, which will find its own readership and which can stimulate significant new research in the topics represented. Overall, as Guest Editors, we feel quite fortunate to have obtained such a strong response to the call for this issue and to have a really wide-ranging collection of high-quality contributions which, indeed, can be read from the first to the last page with sustained enthusiasm. A large number of applications and techniques is represented, overall via 16 contributions with 45 authors in total. This shows, in our opinion, that electromagnetic imaging and inversion remain amongst the most challenging and active research areas in applied inverse problems today. Below, we give a brief overview of the contributions included in this issue, ordered alphabetically by the surname of the leading author. 1. The complexity of handling potential randomness of the source in an inverse scattering problem is not minor, and the literature is far from being replete in this configuration. The contribution by G Bao, S N Chow, P Li and H Zhou, `Numerical solution of an inverse medium scattering problem with a stochastic source', exemplifies how to hybridize Wiener chaos expansion with a recursive linearization method in order to solve the stochastic problem as a set of decoupled deterministic ones. 2. In cases where the forward problem is expensive to evaluate, database methods might become a reliable method of choice, while enabling one to deliver more information on the inversion itself. The contribution by S Bilicz, M Lambert and Sz Gyimóthy, `Kriging-based generation of optimal databases as forward and inverse surrogate models', describes such a technique which uses kriging for constructing an efficient database with the goal of achieving an equidistant distribution of points in the measurement space. 3. Anisotropy remains a considerable challenge in electromagnetic imaging, which is tackled in the contribution by F Cakoni, D Colton, P Monk and J Sun, `The inverse electromagnetic scattering problem for anisotropic media', via the fact that transmission eigenvalues can be retrieved from a far-field scattering pattern, yielding, in particular, lower and upper bounds of the index of refraction of the unknown (dielectric anisotropic) scatterer. 4. So-called subspace optimization methods (SOM) have attracted a lot of interest recently in many fields. The contribution by X Chen, `Subspace-based optimization method for inverse scattering problems with an inhomogeneous background medium', illustrates how to address a realistic situation in which the medium containing the unknown obstacles is not homogeneous, via blending a properly developed SOM with a finite-element approach to the required Green's functions. 5. H Egger, M Hanke, C Schneider, J Schöberl and S Zaglmayr, in their contribution `Adjoint-based sampling methods for electromagnetic scattering', show how to efficiently develop sampling methods without explicit knowledge of the dyadic Green's function once an adjoint problem has been solved at much lower computational cost. This is demonstrated by examples in demanding propagative and diffusive situations. 6. Passive sensor arrays can be employed to image reflectors from ambient noise via proper migration of cross-correlation matrices into their embedding medium. This is investigated, and resolution, in particular, is considered in detail, as a function of the characteristics of the sensor array and those of the noise, in the contribution by J Garnier and G Papanicolaou, `Resolution analysis for imaging with noise'. 7. A direct reconstruction technique based on the conformal mapping theorem is proposed and investigated in depth in the contribution by H Haddar and R Kress, `Conformal mapping and impedance tomography'. This paper expands on previous work, with inclusions in homogeneous media, convergence results, and numerical illustrations. 8. The contribution by T Hohage and S Langer, `Acceleration techniques for regularized Newton methods applied to electromagnetic inverse medium scattering problems', focuses on a spectral preconditioner intended to accelerate regularized Newton methods as employed for the retrieval of a local inhomogeneity in a three-dimensional vector electromagnetic case, while also illustrating the implementation of a Lepskiĭ-type stopping rule outsmarting a traditional discrepancy principle. 9. Geophysical applications are a rich source of practically relevant inverse problems. The contribution by M Li, A Abubakar and T Habashy, `Application of a two-and-a-half dimensional model-based algorithm to crosswell electromagnetic data inversion', deals with a model-based inversion technique for electromagnetic imaging which addresses novel challenges such as multi-physics inversion, and incorporation of prior knowledge, such as in hydrocarbon recovery. 10. Non-stationary inverse problems, considered as a special class of Bayesian inverse problems, are framed via an orthogonal decomposition representation in the contribution by A Lipponen, A Seppänen and J P Kaipio, `Reduced order estimation of nonstationary flows with electrical impedance tomography'. The goal is to simultaneously estimate, from electrical impedance tomography data, certain characteristics of the Navier--Stokes fluid flow model together with time-varying concentration distribution. 11. Non-iterative imaging methods of thin, penetrable cracks, based on asymptotic expansion of the scattering amplitude and analysis of the multi-static response matrix, are discussed in the contribution by W-K Park, `On the imaging of thin dielectric inclusions buried within a half-space', completing, for a shallow burial case at multiple frequencies, the direct imaging of small obstacles (here, along their transverse dimension), MUSIC and non-MUSIC type indicator functions being used for that purpose. 12. The contribution by R Potthast, `A study on orthogonality sampling' envisages quick localization and shaping of obstacles from (portions of) far-field scattering patterns collected at one or more time-harmonic frequencies, via the simple calculation (and summation) of scalar products between those patterns and a test function. This is numerically exemplified for Neumann/Dirichlet boundary conditions and homogeneous/heterogeneous embedding media. 13. The contribution by J D Shea, P Kosmas, B D Van Veen and S C Hagness, `Contrast-enhanced microwave imaging of breast tumors: a computational study using 3D realistic numerical phantoms', aims at microwave medical imaging, namely the early detection of breast cancer. The use of contrast enhancing agents is discussed in detail and a number of reconstructions in three-dimensional geometry of realistic numerical breast phantoms are presented. 14. The contribution by D A Subbarayappa and V Isakov, `Increasing stability of the continuation for the Maxwell system', discusses enhanced log-type stability results for continuation of solutions of the time-harmonic Maxwell system, adding a fresh chapter to the interesting story of the study of the Cauchy problem for PDE. 15. In their contribution, `Recent developments of a monotonicity imaging method for magnetic induction tomography in the small skin-depth regime', A Tamburrino, S Ventre and G Rubinacci extend the recently developed monotonicity method toward the application of magnetic induction tomography in order to map surface-breaking defects affecting a damaged metal component. 16. The contribution by F Viani, P Rocca, M Benedetti, G Oliveri and A Massa, `Electromagnetic passive localization and tracking of moving targets in a WSN-infrastructured environment', contributes to what could still be seen as a niche problem, yet both useful in terms of applications, e.g., security, and challenging in terms of methodologies and experiments, in particular, in view of the complexity of environments in which this endeavor is to take place and the variability of the wireless sensor networks employed. To conclude, we would like to thank the able and tireless work of Kate Watt and Zoë Crossman, as past and present Publishers of the Journal, on what was definitely a long and exciting journey (sometimes a little discouraging when reports were not arriving, or authors were late, or Guest Editors overwhelmed) that started from a thorough discussion at the `Manchester workshop on electromagnetic inverse problems' held mid-June 2009, between Kate Watt and the Guest Editors. We gratefully acknowledge the fact that W W Symes gave us his full backing to carry out this special issue and that A K Louis completed it successfully. Last, but not least, the staff of Inverse Problems should be thanked, since they work together to make it a premier journal.

Nondestructive testing of delaminated interfaces between two materials using electromagnetic interrogation

NASA Astrophysics Data System (ADS)

Cakoni, Fioralba; de Teresa, Irene; Monk, Peter

2018-06-01

We consider the problem of detecting whether two materials that should be in contact have separated or delaminated using electromagnetic radiation. The interface damage is modeled as a thin opening between two materials of different electromagnetic properties. To derive a reconstruction algorithm that focuses on testing for the delamination at the interface between the two materials, we use the approximate asymptotic model for the forward problem derived in de Teresa (2017 PhD Thesis University of Delaware). In this model, the differential equations in the small opening are replaced by approximate transmission conditions for the electromagnetic fields across the interface. We also assume that the undamaged or background state is known and it is desired to find where the delamination has opened. We adapt the linear sampling method to this configuration in order to locate the damaged part of the interface from a knowledge of the scattered field and the undamaged configuration, but without needing to know the electromagnetic properties of the opening. Numerical examples are presented to validate our algorithm.

Optimal illusion and invisibility of multilayered anisotropic cylinders and spheres.

PubMed

Zhang, Lin; Shi, Yan; Liang, Chang-Hong

2016-10-03

In this paper, full-wave electromagnetic scattering theory is employed to investigate illusion and invisibility of inhomogeneous anisotropic cylinders and spheres. With the use of a shell designed according to Mie series theory for multiple piecewise anisotropic layers, radar cross section (RCS) of the coated inhomogeneous anisotropic object can be dramatically reduced or disguised as another object in the long-wavelength limit. With the suitable adjustment of the anisotropy parameters of the shell, optimal illusion and invisibility characteristics of the coated inhomogeneous anisotropic object can be achieved. Details of theoretical analysis and numerical examples are presented to validate the proposed methodology.

Cloud Properties from Satellite Infrared and Visible Measurements

DTIC Science & Technology

1976-12-07

Rudiometer Veta. NOM Teen - nical Memorandum WESS 52. Deiruendjian, D., 1969: Electromagnetic Scatter- ing on Spherical Polydispersions. American...asu m ents, Cloud mass liquid water content, Cloud altitudes, Hydrometeor * erosion DOI PORN 1473 NOV *11’.

Advanced DPSM approach for modeling ultrasonic wave scattering in an arbitrary geometry

NASA Astrophysics Data System (ADS)

Yadav, Susheel K.; Banerjee, Sourav; Kundu, Tribikram

2011-04-01

Several techniques are used to diagnose structural damages. In the ultrasonic technique structures are tested by analyzing ultrasonic signals scattered by damages. The interpretation of these signals requires a good understanding of the interaction between ultrasonic waves and structures. Therefore, researchers need analytical or numerical techniques to have a clear understanding of the interaction between ultrasonic waves and structural damage. However, modeling of wave scattering phenomenon by conventional numerical techniques such as finite element method requires very fine mesh at high frequencies necessitating heavy computational power. Distributed point source method (DPSM) is a newly developed robust mesh free technique to simulate ultrasonic, electrostatic and electromagnetic fields. In most of the previous studies the DPSM technique has been applied to model two dimensional surface geometries and simple three dimensional scatterer geometries. It was difficult to perform the analysis for complex three dimensional geometries. This technique has been extended to model wave scattering in an arbitrary geometry. In this paper a channel section idealized as a thin solid plate with several rivet holes is formulated. The simulation has been carried out with and without cracks near the rivet holes. Further, a comparison study has been also carried out to characterize the crack. A computer code has been developed in C for modeling the ultrasonic field in a solid plate with and without cracks near the rivet holes.

The theory of ionospheric focused heating

NASA Technical Reports Server (NTRS)

Bernhardt, P. A.; Duncan, L. M.

1987-01-01

Ionospheric modification by high power radio waves and by chemical releases are combined in a theoretical study of ionospheric focused heating. The release of materials which promote electron-ion recombination creates a hole in the bottomside ionosphere. The ionospheric hole focuses high power radio waves from a ground-based transmitter to give a 20 dB or greater enhancement in power density. The intense radio beam excites atomic oxygen by collisions with accelerated electrons. Airglow from the excited oxygen provides a visible trace of the focused beam. The large increase in the intensity of the radio beam stimulates new wave-plasma interactions. Numerical simulations show that the threshold for the two-plasmon decay instability is exceeded. The interaction of the pump electromagnetic wave with the backward plasmon produces a scattered electromagnetic wave at 3/2 the pump frequency. The scattered wave provides a unique signature of the two-plasmon decay process for ground-based detection.

Experimental study: Underwater propagation of polarized flat top partially coherent laser beams with a varying degree of spatial coherence

NASA Astrophysics Data System (ADS)

Avramov-Zamurovic, S.; Nelson, C.

2018-10-01

We report on experiments where spatially partially coherent laser beams with flat top intensity profiles were propagated underwater. Two scenarios were explored: still water and mechanically moved entrained salt scatterers. Gaussian, fully spatially coherent beams, and Multi-Gaussian Schell model beams with varying degrees of spatial coherence were used in the experiments. The main objective of our study was the exploration of the scintillation performance of scalar beams, with both vertical and horizontal polarizations, and the comparison with electromagnetic beams that have a randomly varying polarization. The results from our investigation show up to a 50% scintillation index reduction for the case with electromagnetic beams. In addition, we observed that the fully coherent beam performance deteriorates significantly relative to the spatially partially coherent beams when the conditions become more complex, changing from still water conditions to the propagation through mechanically moved entrained salt scatterers.

Exposing strangeness: Projections for kaon electromagnetic form factors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Fei; Chang, Lei; Liu, Yu -Xin

A continuum approach to the kaon and pion bound-state problems is used to reveal their electromagnetic structure. For both systems, when used with parton distribution amplitudes appropriate to the scale of the experiment, Standard Model hard-scattering formulas are accurate to within 25% at momentum transfers Q 2 ≈ 8 GeV 2. There are measurable differences between the distribution of strange and normal matter within the kaons, e.g. the ratio of their separate contributions reaches a peak value of 1.5 at Q 2 ≈ 6 GeV 2. Its subsequent Q 2 evolution is accurately described by the hard scattering formulas. Projectionsmore » for the ratio of kaon and pion form factors at timelike momenta beyond the resonance region are also presented. In conclusion, these results and projections should prove useful in planning next-generation experiments.« less

Exposing strangeness: Projections for kaon electromagnetic form factors

DOE PAGES

Gao, Fei; Chang, Lei; Liu, Yu -Xin; ...

2017-08-28

A continuum approach to the kaon and pion bound-state problems is used to reveal their electromagnetic structure. For both systems, when used with parton distribution amplitudes appropriate to the scale of the experiment, Standard Model hard-scattering formulas are accurate to within 25% at momentum transfers Q 2 ≈ 8 GeV 2. There are measurable differences between the distribution of strange and normal matter within the kaons, e.g. the ratio of their separate contributions reaches a peak value of 1.5 at Q 2 ≈ 6 GeV 2. Its subsequent Q 2 evolution is accurately described by the hard scattering formulas. Projectionsmore » for the ratio of kaon and pion form factors at timelike momenta beyond the resonance region are also presented. In conclusion, these results and projections should prove useful in planning next-generation experiments.« less

Preface: Electromagnetic and Light Scattering by Nonspherical Particles XIV

NASA Technical Reports Server (NTRS)

Dubovik, Oleg; Labonnete, Laurent; Litvinov, Pavel; Parol, Frederic; Mischenko, Michael

2014-01-01

The 14th Electromagnetic and Light Scattering Conference (ELS-XIV) was held at the Universit de Lille 1, Villeneuve d'Ascq, France on 17-21 June 2013. The conference was attended by 200 scientists from 26 countries. The scientific program included one plenary lecture, 12 invited reviews, 100 contributed oral talks, and 86 poster presentations. The program, the abstracts, and the slides of the oral presentations are available at the conference web site http:www-loa.univ-lille1.frELS-XIV. To highlight one of the traditional ELS themes, the ELS-XIV featured a special session on Remote sensing of aerosols and clouds using polarimetric observations. This session was sponsored and co-organized by the French space agency CNES and attracted representatives from nearly all research teams word-wide involved in the development and active use of space-borne, in situ, and ground-based polarimetric observations.

A Characteristic Mode Analysis of Conductive Nanowires and Microwires Above a Lossy Dielectric Half-Space

NASA Astrophysics Data System (ADS)

Kiddle, Daniel S.

Nanowires possess extraordinary mechanical, thermoelectric and electromagnetic properties which led to their incorporation in a wide variety of applications. The purpose of this study is to investigate the effect of material on the electromagnetic response of these nanowires. We used the Method of Moments (MOM) for Arbitrarily Thin Wire (ATW) formulation as an efficient computational technique for calculating the electromagnetic response of nanowires. To explain the calculated electromagnetic response, we evoked the Characteristic Mode Analysis (CMA) which decomposes the current on the wire into a superposition of fundamental current modes. These modes are weighted by two coefficients: (i) the relative importance of each mode at a certain frequency, termed Modal Significance, and (ii) the level of coupling between the incident field and the mode termed the Modal Excitation Coefficient. In this, work we study how the wire's material affect the Modal Significance and the Modal Excitation Coefficient of nanowires. Our results show that the material of the nanowire has a strong effect on the resonance frequency, the bandwidth, and the overlap of the modes showing that the material of the nanowire can be used as a tuning factor to develop sensors with desired radiation characteristics. Nanowires are commonly grown vertically on a substrate and, therefore, we also study the effect of the presence of a lossy dielectric half-space on their electromagnetic response. To efficiently account for this interface, we utilize a modified Green's function using the rigorous Sommerfeld integrals. Our results show that the relative permittivity of the substrate decreases the resonance frequencies of the nanowires and significantly alters their radiation patterns. Most importantly, we find that, if the nanowire is near the interface, its evanescent field's couple to the dielectric half space leading to the majority of the scattered power radiated into the substrate with high directivity. The results of this thesis has the potential to quantify the electromagnetic response of vertical nanowires in their realistic environment as well as facilitate the incorporation of nanowires in novel sensing applications.

Experimental light scattering by positionally-controlled small particles — Implications for Planetary Science

NASA Astrophysics Data System (ADS)

Gritsevich, M.; Penttilä, A.; Maconi, G.; Kassamakov, I.; Martikainen, J.; Markkanen, J.; Vaisanen, T.; Helander, P.; Puranen, T.; Salmi, A.; Hæggström, E.; Muinonen, K.

2017-12-01

Electromagnetic scattering is a fundamental physical process that allows inferring characteristics of an object studied remotely. This possibility is enhanced by obtaining the light-scattering response at multiple wavelengths and viewing geometries, i.e., by considering a wider range of the phase angle (the angle between the incident light and the light reflected from the object) in the experiment. Within the ERC Advanced Grant project SAEMPL (http://cordis.europa.eu/project/rcn/107666_en.html) we have assembled an interdisciplinary group of scientists to develop a fully automated, 3D scatterometer that can measure scattered light at different wavelengths from small particulate samples. The setup comprises: (a) the PXI Express platform to synchronously record data from several photomultiplier tubes (PMTs); (b) a motorized rotation stage to precisely control the azimuthal angle of the PMTs around 360°; and (c) a versatile light source, whose wavelength, polarization, intensity, and beam shape can be precisely controlled. An acoustic levitator is used to hold the sample without touching it. The device is the first of its kind, since it measures controlled spectral angular scattering including all polarization effects, for an arbitrary object in the µm-cm size scale. It permits a nondestructive, disturbance-free measurement with control of the orientation and location of the scattering object. To demonstrate our approach we performed detailed measurements of light scattered by a Chelyabinsk LL5 chondrite particle, derived from the light-colored lithology sample of the meteorite. These measurements are cross-validated against the modeled light-scattering characteristics of the sample, i.e., the intensity and the degree of linear polarization of the reflected light, calculated with state-of-the-art electromagnetic techniques (see Muinonen et al., this meeting). We demonstrate a unique non-destructive approach to derive the optical properties of small grain samples which facilitates research on highly valuable planetary materials, such as samples returned from space missions or rare meteorites.

Detection of Two Buried Cross Pipelines by Observation of the Scattered Electromagnetic Field

NASA Astrophysics Data System (ADS)

Mangini, Fabio; Di Gregorio, Pietro Paolo; Frezza, Fabrizio; Muzi, Marco; Tedeschi, Nicola

2015-04-01

In this work we present a numerical study on the effects that can be observed in the electromagnetic scattering of a plane wave due to the presence of two crossed pipelines buried in a half-space occupied by cement. The pipeline, supposed to be used for water conveyance, is modeled as a cylindrical shell made of metallic or poly-vinyl chloride (PVC) material. In order to make the model simpler, the pipelines are supposed running parallel to the air-cement interface on two different parallel planes; moreover, initially we suppose that the two tubes make an angle of 90 degrees. We consider a circularly-polarized plane wave impinging normally to the interface between air and the previously-mentioned medium, which excites the structure in order to determine the most useful configuration in terms of scattered-field sensitivity. To perform the study, a commercially available simulator which implements the Finite Element Method was adopted. A preliminary frequency sweep allows us to choose the most suitable operating frequency depending on the dimensions of the commercial pipeline cross-section. We monitor the three components of the scattered electric field along a line just above the interface between the two media. The electromagnetic properties of the materials employed in this study are taken from the literature and, since a frequency-domain technique is adopted, no further approximation is needed. Once the ideal problem has been studied, i.e. having considered orthogonal and tangential scenario, we further complicate the model by considering different crossing angles and distances between the tubes, in two cases of PVC and metallic material. The results obtained in these cases are compared with those of the initial problem with the goal of determining the scattered field dependence on the geometrical characteristics of the cross between two pipelines. One of the practical applications in the field of Civil Engineering of this study may be the use of ground penetrating radar (GPR) techniques to monitor the fouling conditions of water pipelines without the need to intervene destructively on the structure. Acknowledgements: This work is a contribution to COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar".

Effect of the magnetic field on coexisting stimulated Raman and Brillouin backscattering of an extraordinary mode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vyas, Ashish, E-mail: ashishvyas.optics@gmail.com; Singh, Ram Kishor, E-mail: ram007kishor@gmail.com; Sharma, R. P., E-mail: rpsharma@ces.iitd.ernet.in

2016-01-15

This paper presents a model to study the interplay between the stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) in the presence of background magnetic field. This formalism is applicable to laser produced plasma as well as to heating mechanism in toroidal system by an extraordinary electromagnetic wave. In the former case, the magnetic field is self-generated, while in the latter case (toroidal plasmas) magnetic field is applied externally. The behavior of one scattering process is explicitly dependent on the coexisting scattering process as well as on the magnetic field. Explicit expressions for the back-reflectivity of scattered beams (SRSmore » and SBS) are presented. It has been demonstrated that due to the magnetic field and coexistence of the scattering processes (SRS and SBS) the back-reflectivity gets modified significantly. Results are also compared with the three wave interaction case (isolated SRS or SBS case)« less

Inverse atmospheric radiative transfer problems - A nonlinear minimization search method of solution. [aerosol pollution monitoring

NASA Technical Reports Server (NTRS)

Fymat, A. L.

1976-01-01

The paper studies the inversion of the radiative transfer equation describing the interaction of electromagnetic radiation with atmospheric aerosols. The interaction can be considered as the propagation in the aerosol medium of two light beams: the direct beam in the line-of-sight attenuated by absorption and scattering, and the diffuse beam arising from scattering into the viewing direction, which propagates more or less in random fashion. The latter beam has single scattering and multiple scattering contributions. In the former case and for single scattering, the problem is reducible to first-kind Fredholm equations, while for multiple scattering it is necessary to invert partial integrodifferential equations. A nonlinear minimization search method, applicable to the solution of both types of problems has been developed, and is applied here to the problem of monitoring aerosol pollution, namely the complex refractive index and size distribution of aerosol particles.

Modeling of Graphene Planar Grating in the THz Range by the Method of Singular Integral Equations

NASA Astrophysics Data System (ADS)

Kaliberda, Mstislav E.; Lytvynenko, Leonid M.; Pogarsky, Sergey A.

2018-04-01

Diffraction of the H-polarized electromagnetic wave by the planar graphene grating in the THz range is considered. The scattering and absorption characteristics are studied. The scattered field is represented in the spectral domain via unknown spectral function. The mathematical model is based on the graphene surface impedance and the method of singular integral equations. The numerical solution is obtained by the Nystrom-type method of discrete singularities.

Application of semiclassical and geometrical optics theories to resonant modes of a coated sphere.

PubMed

Bambino, Túlio M; Breitschaft, Ana Maria S; Barbosa, Valmar C; Guimarães, Luiz G

2003-03-01

This work deals with some aspects of the resonant scattering of electromagnetic waves by a metallic sphere covered by a dielectric layer, in the weak-absorption approximation. We carry out a geometrical optics treatment of the scattering and develop semiclassical formulas to determine the positions and widths of the system resonances. In addition, we show that the mean lifetime of broad resonances is strongly dependent on the polarization of the incident light.

Radiation Force Caused by Scattering, Absorption, and Emission of Light by Nonspherical Particles

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Hansen, James E. (Technical Monitor)

2001-01-01

General formulas for computing the radiation force exerted on arbitrarily oriented and arbitrarily shaped nonspherical particles due to scattering, absorption, and emission of electromagnetic radiation are derived. For randomly oriented particles with a plane of symmetry, the formula for the average radiation force caused by the particle response to external illumination reduces to the standard Debye formula derived from the Lorenz-Mie theory, whereas the average radiation force caused by emission vanishes.

Feature Extraction Using Attributed Scattering Center Models for Model-Based Automatic Target Recognition (ATR)

DTIC Science & Technology

2005-10-01

section of the coiled arm. Right: measured realized total gain for a square spiral in free space with inductive treatment. . . . . . . . 154 8.5 Initial...appreciable velocities can often be easily separated from clutter returns, slow moving targets of more moderate cross sections can be very difficult to detect...electromagnetic radiation and measuring the energy scattered back. The data obtained as a result of this process is a finite-extent, noisy set of

Evidence for anomalous prompt photons in deep inelastic muon scattering at 200 GeV

NASA Astrophysics Data System (ADS)

Aubert, J. J.; Bassompierre, G.; Becks, K. H.; Benchouk, C.; Best, C.; Böhm, E.; De Bouard, X.; Brasse, F. W.; Broll, C.; Brown, S. C.; Carr, J.; Clifft, R.; Cobb, J. H.; Coignet, G.; Combley, F.; Court, G. R.; D'Agostini, G.; Dau, W. D.; Davies, J. K.; Déclais, Y.; Dosselli, U.; Drees, J.; Edwards, A.; Edwards, M.; Favier, J.; Ferrero, M. I.; Flauger, W.; Forsbach, H.; Gabathuler, E.; Gamet, R.; Gayler, J.; Gerhardt, V.; Gössling, C.; Gregory, P.; Haas, J.; Hamacher, K.; Hayman, P.; Henckes, M.; Ingelman, G.; Korbel, V.; Landgraf, U.; Leenen, M.; Maire, M.; Mohr, W.; Montgomery, H. E.; Moser, K.; Muont, R. P.; Nagy, E.; Nassalski, J.; Norton, P. R.; McNicholas, J.; Osborne, A. M.; Payre, P.; Peroni, C.; Pessard, H.; Pietrzyk, U.; Rith, K.; Schneegans, M.; Sloan, T.; Stier, H. E.; Stockhausen, W.; Thénard, J. M.; Thompson, J. C.; Urban, L.; Wahlen, H.; Whalley, M.; Williams, D.; Williams, W. S. C.; Williamson, J.; Wimpenny, S. J.; European Muon Collaboration

1989-02-01

The inclusive yield of photons has been measured from deep inelastic interactions of 200 GeV muons on hydrogen. After subtracting the contributions from hadron electromagnetic decays and Bethe-Heitler muon bremsstrahlung, residual photons are observed at low pT and low z at a mean level of 0.15±0.06 per interaction. The quark Compton scattering process is unable to explain the data, thus indicating an anomalous photon production.

Fast online inverse scattering with Reduced Basis Method (RBM) for a 3D phase grating with specific line roughness

NASA Astrophysics Data System (ADS)

Kleemann, Bernd H.; Kurz, Julian; Hetzler, Jochen; Pomplun, Jan; Burger, Sven; Zschiedrich, Lin; Schmidt, Frank

2011-05-01

Finite element methods (FEM) for the rigorous electromagnetic solution of Maxwell's equations are known to be very accurate. They possess a high convergence rate for the determination of near field and far field quantities of scattering and diffraction processes of light with structures having feature sizes in the range of the light wavelength. We are using FEM software for 3D scatterometric diffraction calculations allowing the application of a brilliant and extremely fast solution method: the reduced basis method (RBM). The RBM constructs a reduced model of the scattering problem from precalculated snapshot solutions, guided self-adaptively by an error estimator. Using RBM, we achieve an efficiency accuracy of about 10-4 compared to the direct problem with only 35 precalculated snapshots being the reduced basis dimension. This speeds up the calculation of diffraction amplitudes by a factor of about 1000 compared to the conventional solution of Maxwell's equations by FEM. This allows us to reconstruct the three geometrical parameters of our phase grating from "measured" scattering data in a 3D parameter manifold online in a minute having the full FEM accuracy available. Additionally, also a sensitivity analysis or the choice of robust measuring strategies, for example, can be done online in a few minutes.

Entropy-Based Classification of Subsurface Scatterers: A Valuable Tool for the Analysis of Data Obtained by the Fully Polarimetric WISDOM Radar

NASA Astrophysics Data System (ADS)

Plettemeier, D.; Statz, C.; Hahnel, R.; Benedix, W. S.; Hamran, S. E.; Ciarletti, V.

2016-12-01

The "Water Ice Subsurface Deposition on Mars" Experiment (WISDOM) is a Ground Penetrating Radar (GPR) and part of the 2020 ExoMars Rover payload. It will be the first GPR operating on a planetary rover and the first fully polarimetric radar tasked at probing the subsurface of Mars. WISDOM operates at frequencies between 500 MHz and 3 GHz yielding a centimetric resolution and a penetration depth of about 3 meters in Martian soil. Its prime scientific objective is the detailed characterization of the material distribution within the first few meters of the Martian subsurface as a contribution to the search for evidence of past life. For the first time, WISDOM will give access to the geological structure, electromagnetic nature, and hydrological state of the shallow subsurface by retrieving the layering and properties of the buried reflectors at an unprecedented resolution and, due to the fully polarimetric measurements, amount of information. Furthermore, a "real time" subsurface analysis will support the drill operations by identifying locations of high scientific interest and low risk. Key element in the WISDOM data analysis is the fast and reliable classification and correct localization of subsurface scatterers and layers. The fully polarimetric nature of the WISDOM measurements allows the use of the entropy-alpha decomposition (H-alpha). This method enables the classification of reconstructed images of the subsurface (obtained by inverse imaging algorithms, e.g. f-k migration) with regard to the main scattering mechanisms of geological features present in the image of the subsurface. It is, for example, possible to differentiate smooth surfaces, rough surfaces, isolated spherical scatterers, double- and bounce scattering, anisotropic scatterers, clouds of small scatterers of similar shape as well as layers of oblate spheroids. Preliminary tests under laboratory conditions suggest the feasibility and value of the approach for the classification of geological features in the Martian subsurface in the context of WISDOM data processing and operations. It is a fast and reliable tool leveraging the whole amount of information provided by the fully polarimetric WISDOM Radar.

A finite element: Boundary integral method for electromagnetic scattering. Ph.D. Thesis Technical Report, Feb. - Sep. 1992

NASA Technical Reports Server (NTRS)

Collins, J. D.; Volakis, John L.

1992-01-01

A method that combines the finite element and boundary integral techniques for the numerical solution of electromagnetic scattering problems is presented. The finite element method is well known for requiring a low order storage and for its capability to model inhomogeneous structures. Of particular emphasis in this work is the reduction of the storage requirement by terminating the finite element mesh on a boundary in a fashion which renders the boundary integrals in convolutional form. The fast Fourier transform is then used to evaluate these integrals in a conjugate gradient solver, without a need to generate the actual matrix. This method has a marked advantage over traditional integral equation approaches with respect to the storage requirement of highly inhomogeneous structures. Rectangular, circular, and ogival mesh termination boundaries are examined for two-dimensional scattering. In the case of axially symmetric structures, the boundary integral matrix storage is reduced by exploiting matrix symmetries and solving the resulting system via the conjugate gradient method. In each case several results are presented for various scatterers aimed at validating the method and providing an assessment of its capabilities. Important in methods incorporating boundary integral equations is the issue of internal resonance. A method is implemented for their removal, and is shown to be effective in the two-dimensional and three-dimensional applications.

Organo luminescent semiconductor nanocrystal probes for biological applications and process for making and using such probes

DOEpatents

Weiss, Shimon; Bruchez, Jr., Marcel; Alivisatos, Paul

2006-09-05

A semiconductor nanocrystal compound is described capable of linking to an affinity molecule. The compound comprises (1) a semiconductor nanocrystal capable of emitting electromagnetic radiation and/or absorbing energy, and/or scattering or diffracting electromagnetic radiation--when excited by an electromagnetic radiation source or a particle beam; and (2) at least one linking agent, having a first portion linked to the semiconductor nanocrystal and a second portion capable of linking to an affinity molecule. The compound is linked to an affinity molecule to form a semiconductor nanocrystal probe capable of bonding with a detectable substance. subsequent exposure to excitation energy will excite the semiconductor nanocrystal in the probe causing the emission of electromagnetic radiation. Further described are processes for respectively: making the luminescent semiconductor nanocrystal compound; making the semiconductor nanocrystal probe; and using the probe to determine the presence of a detectable substance in a material.

Organo luminescent semiconductor nanocrystal probes for biological applications and process for making and using such probes

DOEpatents

Weiss, Shimon [Pinole, CA; Bruchez, Jr., Marcel; Alivisatos, Paul [Oakland, CA

2004-03-02

A semiconductor nanocrystal compound is described capable of linking to an affinity molecule. The compound comprises (1) a semiconductor nanocrystal capable of emitting electromagnetic radiation and/or absorbing energy, and/or scattering or diffracting electromagnetic radiation--when excited by an electromagnetic radiation source or a particle beam; and (2) at least one linking agent, having a first portion linked to the semiconductor nanocrystal and a second portion capable of linking to an affinity molecule. The compound is linked to an affinity molecule to form a semiconductor nanocrystal probe capable of bonding with a detectable substance. Subsequent exposure to excitation energy will excite the semiconductor nanocrystal in the probe, causing the emission of electromagnetic radiation. Further described are processes for respectively: making the semiconductor nanocrystal compound; making the semiconductor nanocrystal probe; and using the probe to determine the presence of a detectable substance in a material.

Organo luminescent semiconductor nanocrystal probes for biological applications and process for making and using such probes

DOEpatents

Weiss, Shimon; Bruchez, Jr., Marcel; Alivisatos, Paul

2005-08-09

A semiconductor nanocrystal compound is described capable of linking to an affinity molecule. The compound comprises (1) a semiconductor nanocrystal capable of emitting electromagnetic radiation and/or absorbing energy, and/or scattering or diffracting electromagnetic radiation--when excited by an electromagnetic radiation source or a particle beam; and (2) at least one linking agent, having a first portion linked to the semiconductor nanocrystal and a second portion capable of linking to an affinity molecule. The compound is linked to an affinity molecule to form a semiconductor nanocrystal probe capable of bonding with a detectable substance. Subsequent exposure to excitation energy will excite the semiconductor nanocrystal in the probe causing the emission of electromagnetic radiation. Further described are processes for respectively: making the luminescent semiconductor nanocrystal compound; making the semiconductor nanocrystal probe; and using the probe to determine the presence of a detectable substance in a material.

Organo luminescent semiconductor nanocrystal probes for biological applications and process for making and using such probes

DOEpatents

Weiss, Shimon; Bruchez, Jr., Marcel; Alivisatos, Paul

2002-01-01

A semiconductor nanocrystal compound is described capable of linking to an affinity molecule. The compound comprises (1) a semiconductor nanocrystal capable of emitting electromagnetic radiation and/or absorbing energy, and/or scattering or diffracting electromagnetic radiation--when excited by an electromagnetic radiation source or a particle beam; and (2) at least one linking agent, having a first portion linked to the semiconductor nanocrystal and a second portion capable of linking to an affity molecule. The compound is linked to an affinity molecule to form a semiconductor nanocrystal probe capable of bonding with a detectable substance. Subsequent exposure to excitation energy will excite the semiconductor nanocrystal in he probe, causing the emission of electromagnetic radiation. Further described are processes for respectively: making the semiconductor nanocrystal compound; making the semiconductor nanocrystal probe; and using the probe to determine the presence of a detectable substance in a material.

Electromagnetic processes in the atmosphere of pulsars

NASA Technical Reports Server (NTRS)

Yukhimuk, A. K.

1974-01-01

The work consists of two parts. The first deals with the fine structure of radio pulses. Based on kinetic theory, processes occurring in the plasma shell of a pulsar when external electromagnetic radiation is present are investigated. It is shown that electromagnetic waves cause electrons to drift relative to ions, and initiate longitudinal oscillations. A dispersion equation describing the longitudinal oscillations in magnetized plasma is derived. Conditions for excitation of oscillations are found. Correlation functions of electron density are calculated, along with the coefficients of electromagnetic wave scattering. It is shown that variations in the amplitude of pulsar pulses are associated with scintillations caused by fluctuations in the plasma electron density. The second part of the study presents a mechanism for the radio emission of pulsars. The model of a rotating and a pulsating star, a neutron star with dipolar or more complex magnetic field, is examined.

Semianalytical model for the electromagnetic enhancement by a rectangular nanowire optical antenna on metallic substrate.

PubMed

Wan, Jianing; Zhu, Junda; Zhong, Ying; Liu, Haitao

2018-06-01

The electromagnetic enhancement by a metallic nanowire optical antenna on metallic substrate is investigated theoretically. By considering the excitation and multiple scattering of surface plasmon polaritons in the nanogap between the antenna and the substrate, we build up an intuitive and comprehensive model that provides semianalytical expressions for the electromagnetic field in the nanogap to achieve an understanding of the mechanism of electromagnetic enhancement. Our results show that antennas with short lengths that support the lowest order of resonance can achieve a high electric-field enhancement factor over a large range of incidence angles. Two phase-matching conditions are derived from the model for predicting the antenna lengths at resonance. Excitation of symmetric or antisymmetric localized surface plasmon resonance is further explained with the model. The model also shows superior computational efficiency compared to the full-wave numerical method when scanning the antenna length, the incidence angle, or the wavelength.

Relativistic effects in ab initio electron-nucleus scattering

NASA Astrophysics Data System (ADS)

Rocco, Noemi; Leidemann, Winfried; Lovato, Alessandro; Orlandini, Giuseppina

2018-05-01

The electromagnetic responses obtained from Green's function Monte Carlo (GFMC) calculations are based on realistic treatments of nuclear interactions and currents. The main limitations of this method comes from its nonrelativistic nature and its computational cost, the latter hampering the direct evaluation of the inclusive cross sections as measured by experiments. We extend the applicability of GFMC in the quasielastic region to intermediate momentum transfers by performing the calculations in a reference frame that minimizes nucleon momenta. Additional relativistic effects in the kinematics are accounted for employing the two-fragment model. In addition, we developed a novel algorithm, based on the concept of first-kind scaling, to compute the inclusive electromagnetic cross section of 4He through an accurate and reliable interpolation of the response functions. A very good agreement is obtained between theoretical and experimental cross sections for a variety of kinematical setups. This offers a promising prospect for the data analysis of neutrino-oscillation experiments that requires an accurate description of nuclear dynamics in which relativistic effects are fully accounted for.

Proton Form Factor Puzzle and the CEBAF Large Acceptance Spectrometer (CLAS) two-photon exchange experiment

NASA Astrophysics Data System (ADS)

Rimal, Dipak

The electromagnetic form factors are the most fundamental observables that encode information about the internal structure of the nucleon. The electric (GE) and the magnetic ( GM) form factors contain information about the spatial distribution of the charge and magnetization inside the nucleon. A significant discrepancy exists between the Rosenbluth and the polarization transfer measurements of the electromagnetic form factors of the proton. One possible explanation for the discrepancy is the contributions of two-photon exchange (TPE) effects. Theoretical calculations estimating the magnitude of the TPE effect are highly model dependent, and limited experimental evidence for such effects exists. Experimentally, the TPE effect can be measured by comparing the ratio of positron-proton elastic scattering cross section to that of the electron-proton [R = sigma(e +p)/sigma(e+p)]. The ratio R was measured over a wide range of kinematics, utilizing a 5.6 GeV primary electron beam produced by the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. This dissertation explored dependence of R on kinematic variables such as squared four-momentum transfer (Q2) and the virtual photon polarization parameter (epsilon). A mixed electron-positron beam was produced from the primary electron beam in experimental Hall B. The mixed beam was scattered from a liquid hydrogen (LH2) target. Both the scattered lepton and the recoil proton were detected by the CEBAF Large Acceptance Spectrometer (CLAS). The elastic events were then identified by using elastic scattering kinematics. This work extracted the Q2 dependence of R at high epsilon(epsilon > 0.8) and the $epsilon dependence of R at approx 0.85 GeV2. In these kinematics, our data confirm the validity of the hadronic calculations of the TPE effect by Blunden, Melnitchouk, and Tjon. This hadronic TPE effect, with additional corrections contributed by higher excitations of the intermediate state nucleon, largely reconciles the Rosenbluth and the polarization transfer measurements of the electromagnetic form factors.

Hypercube matrix computation task

NASA Technical Reports Server (NTRS)

Calalo, R.; Imbriale, W.; Liewer, P.; Lyons, J.; Manshadi, F.; Patterson, J.

1987-01-01

The Hypercube Matrix Computation (Year 1986-1987) task investigated the applicability of a parallel computing architecture to the solution of large scale electromagnetic scattering problems. Two existing electromagnetic scattering codes were selected for conversion to the Mark III Hypercube concurrent computing environment. They were selected so that the underlying numerical algorithms utilized would be different thereby providing a more thorough evaluation of the appropriateness of the parallel environment for these types of problems. The first code was a frequency domain method of moments solution, NEC-2, developed at Lawrence Livermore National Laboratory. The second code was a time domain finite difference solution of Maxwell's equations to solve for the scattered fields. Once the codes were implemented on the hypercube and verified to obtain correct solutions by comparing the results with those from sequential runs, several measures were used to evaluate the performance of the two codes. First, a comparison was provided of the problem size possible on the hypercube with 128 megabytes of memory for a 32-node configuration with that available in a typical sequential user environment of 4 to 8 megabytes. Then, the performance of the codes was anlyzed for the computational speedup attained by the parallel architecture.

Solution of cavity resonance and waveguide scattering problems using the eigenmode projection technique

NASA Astrophysics Data System (ADS)

Nasr, Mamdouh H.; Othman, Mohamed A. K.; Eshrah, Islam A.; Abuelfadl, Tamer M.

2017-04-01

New developments in the eigenmode projection technique (EPT) are introduced in solving problems of electromagnetic resonance in closed cavities as well as scattering from discontinuities in guided-wave structures. The EPT invokes the eigenmodes of a canonical predefined cavity in the solution procedure and uses the expansion of these eigenmodes to solve Maxwell's equations, in conjunction with a convenient choice of port boundary conditions. For closed cavities, a new spurious-mode separation method is developed, showing robust and efficient spurious-mode separation. This has been tested using more complex and practical examples demonstrating the powerful use of the presented approach. For waveguide scattering problems, convergence studies are being performed showing stable solutions for a relatively small number of expansion modes, and the proposed method has advantages over conventional solvers in analyzing electromagnetic problems with inhomogeneous materials. These convergence studies also lead to an efficient rule-of-thumb for the number of modes to be used in the simulation. The ability to handle closed and open structures is presented in a unified framework that highlights the generality of the EPT which could be used to analyze and design a variety of microwave components.

Stimulated scattering of electromagnetic waves carrying orbital angular momentum in quantum plasmas.

PubMed

Shukla, P K; Eliasson, B; Stenflo, L

2012-07-01

We investigate stimulated scattering instabilities of coherent circularly polarized electromagnetic (CPEM) waves carrying orbital angular momentum (OAM) in dense quantum plasmas with degenerate electrons and nondegenerate ions. For this purpose, we employ the coupled equations for the CPEM wave vector potential and the driven (by the ponderomotive force of the CPEM waves) equations for the electron and ion plasma oscillations. The electrons are significantly affected by the quantum forces (viz., the quantum statistical pressure, the quantum Bohm potential, as well as the electron exchange and electron correlations due to electron spin), which are included in the framework of the quantum hydrodynamical description of the electrons. Furthermore, our investigation of the stimulated Brillouin instability of coherent CPEM waves uses the generalized ion momentum equation that includes strong ion coupling effects. The nonlinear equations for the coupled CPEM and quantum plasma waves are then analyzed to obtain nonlinear dispersion relations which exhibit stimulated Raman, stimulated Brillouin, and modulational instabilities of CPEM waves carrying OAM. The present results are useful for understanding the origin of scattered light off low-frequency density fluctuations in high-energy density plasmas where quantum effects are eminent.

Controlling runaway vortex via externally injected high-frequency electromagnetic waves

NASA Astrophysics Data System (ADS)

Guo, Zehua; McDevitt, Chris; Tang, Xianzhu

2017-10-01

One way of mitigating runaway damage of the plasma-facing components in a tokamak fusion reactor is by limiting the runaway electron energy under a few MeV, while not necessarily reducing the runaway current appreciably. Here we describe a physics mechanism by which such momentum space engineering of the runaway distribution can be facilitated by externally injected high-frequency electromagnetic waves such as the whistler waves. The drastic impact that wave-induced scattering can have on the runaway energy distribution is fundamentally the result of its ability to control the runaway vortex in the momentum space. The runaway vortex, which is a local circulation of runaways in momentum space, is the outcome of the competition between Coulomb collisions, synchrotron radiation damping, and runaway acceleration by parallel electric field. By introducing a wave that resonantly interacts with runaways at a particular range of energy that is mildly relativistic, the enhanced scattering would reshape the vortex by cutting off the part that is highly relativistic. The efficiency of resonant scattering accentuates the requirement that the wave amplitude can be small so the power requirement from external wave injection is practical for the mitigation scheme.

Numerical results for near surface time domain electromagnetic exploration: a full waveform approach

NASA Astrophysics Data System (ADS)

Sun, H.; Li, K.; Li, X., Sr.; Liu, Y., Sr.; Wen, J., Sr.

2015-12-01

Time domain or Transient electromagnetic (TEM) survey including types with airborne, semi-airborne and ground play important roles in applicants such as geological surveys, ground water/aquifer assess [Meju et al., 2000; Cox et al., 2010], metal ore exploration [Yang and Oldenburg, 2012], prediction of water bearing structures in tunnels [Xue et al., 2007; Sun et al., 2012], UXO exploration [Pasion et al., 2007; Gasperikova et al., 2009] etc. The common practice is introducing a current into a transmitting (Tx) loop and acquire the induced electromagnetic field after the current is cut off [Zhdanov and Keller, 1994]. The current waveforms are different depending on instruments. Rectangle is the most widely used excitation current source especially in ground TEM. Triangle and half sine are commonly used in airborne and semi-airborne TEM investigation. In most instruments, only the off time responses are acquired and used in later analysis and data inversion. Very few airborne instruments acquire the on time and off time responses together. Although these systems acquire the on time data, they usually do not use them in the interpretation.This abstract shows a novel full waveform time domain electromagnetic method and our recent modeling results. The benefits comes from our new algorithm in modeling full waveform time domain electromagnetic problems. We introduced the current density into the Maxwell's equation as the transmitting source. This approach allows arbitrary waveforms, such as triangle, half-sine, trapezoidal waves or scatter record from equipment, being used in modeling. Here, we simulate the establishing and induced diffusion process of the electromagnetic field in the earth. The traditional time domain electromagnetic with pure secondary fields can also be extracted from our modeling results. The real time responses excited by a loop source can be calculated using the algorithm. We analyze the full time gates responses of homogeneous half space and two layered models with half sine current waveform as examples. We find the on time responses are quite sensitive to resistivity or depth changes. The results show the potential use of full waveform responses in time domain electromagnetic surveys.

An Alternate Set of Basis Functions for the Electromagnetic Solution of Arbitrarily-Shaped, Three-Dimensional, Closed, Conducting Bodies Using Method of Moments

NASA Technical Reports Server (NTRS)

Mackenzie, Anne I.; Baginski, Michael E.; Rao, Sadasiva M.

2008-01-01

In this work, we present an alternate set of basis functions, each defined over a pair of planar triangular patches, for the method of moments solution of electromagnetic scattering and radiation problems associated with arbitrarily-shaped, closed, conducting surfaces. The present basis functions are point-wise orthogonal to the pulse basis functions previously defined. The prime motivation to develop the present set of basis functions is to utilize them for the electromagnetic solution of dielectric bodies using a surface integral equation formulation which involves both electric and magnetic cur- rents. However, in the present work, only the conducting body solution is presented and compared with other data.

Numerical study of electromagnetic scattering from one-dimensional nonlinear fractal sea surface

NASA Astrophysics Data System (ADS)

Xie, Tao; He, Chao; William, Perrie; Kuang, Hai-Lan; Zou, Guang-Hui; Chen, Wei

2010-02-01

In recent years, linear fractal sea surface models have been developed for the sea surface in order to establish an electromagnetic backscattering model. Unfortunately, the sea surface is always nonlinear, particularly at high sea states. We present a nonlinear fractal sea surface model and derive an electromagnetic backscattering model. Using this model, we numerically calculate the normalized radar cross section (NRCS) of a nonlinear sea surface. Comparing the averaged NRCS between linear and nonlinear fractal models, we show that the NRCS of a linear fractal sea surface underestimates the NRCS of the real sea surface, especially for sea states with high fractal dimensions, and for dominant ocean surface gravity waves that are either very short or extremely long.

Collision effects on propagation characteristics of electromagnetic waves in a sub-wavelength plasma slab of partially ionized dense plasmas

NASA Astrophysics Data System (ADS)

Bowen, LI; Zhibin, WANG; Qiuyue, NIE; Xiaogang, WANG; Fanrong, KONG; Zhenyu, WANG

2018-01-01

Intensive collisions between electrons and neutral particles in partially ionized plasmas generated in atmospheric/sub-atmospheric pressure environments can sufficiently affect the propagation characteristics of electromagnetic waves, particularly in the sub-wavelength regime. To investigate the collisional effect in such plasmas, we introduce a simplified plasma slab model with a thickness on the order of the wavelength of the incident electromagnetic wave. The scattering matrix method (SMM) is applied to solve the wave equation in the plasma slab with significant nonuniformity. Results show that the collisions between the electrons and the neutral particles, as well as the incident angle and the plasma thickness, can disturb the transmission and reduce reflection significantly.

Microwave backscattering theory and active remote sensing of the ocean surface

NASA Technical Reports Server (NTRS)

Brown, G. S.; Miller, L. S.

1977-01-01

The status is reviewed of electromagnetic scattering theory relative to the interpretation of microwave remote sensing data acquired from spaceborne platforms over the ocean surface. Particular emphasis is given to the assumptions which are either implicit or explicit in the theory. The multiple scale scattering theory developed during this investigation is extended to non-Gaussian surface statistics. It is shown that the important statistic for the case is the probability density function of the small scale heights conditioned on the large scale slopes; this dependence may explain the anisotropic scattering measurements recently obtained with the AAFE Radscat. It is noted that present surface measurements are inadequate to verify or reject the existing scattering theories. Surface measurements are recommended for qualifying sensor data from radar altimeters and scatterometers. Additional scattering investigations are suggested for imaging type radars employing synthetically generated apertures.

Thomson scattering in inhomogeneous plasmas: The Role of the Fluctuation-Dissipation Theorem.

PubMed

Belyi, V V

2018-05-21

A self-consistent kinetic theory of Thomson scattering of an electromagnetic field by a non-uniform plasma is derived. We draw the readers' attention to the inconsistency in recent results on the Thomson scattering in inhomogeneous plasma, which leads to violation of the Fluctuation-Dissipation Theorem. We show, that not only the imaginary part, but also the derivatives of the real part of the dielectric susceptibility determine the amplitude and the width of the Thomson scattering spectral lines. As a result of inhomogeneity, these properties become asymmetric with respect to inversion of the sign of the frequency. A method is proposed for measuring local gradients of the electron density with the aid of Thomson scattering.Arising from: P. Kozlowski, et al. Sci. Rep. 6, 24283 (2016); https://doi.org/10.1038/srep24283 .

Modelling the light-scattering properties of a planetary-regolith analog sample

NASA Astrophysics Data System (ADS)

Vaisanen, T.; Markkanen, J.; Hadamcik, E.; Levasseur-Regourd, A. C.; Lasue, J.; Blum, J.; Penttila, A.; Muinonen, K.

2017-12-01

Solving the scattering properties of asteroid surfaces can be made cheaper, faster, and more accurate with reliable physics-based electromagnetic scattering programs for large and dense random media. Existing exact methods fail to produce solutions for such large systems and it is essential to develop approximate methods. Radiative transfer (RT) is an approximate method which works for sparse random media such as atmospheres fails when applied to dense media. In order to make the method applicable to dense media, we have developed a radiative-transfer coherent-backscattering method (RT-CB) with incoherent interactions. To show the current progress with the RT-CB, we have modeled a planetary-regolith analog sample. The analog sample is a low-density agglomerate produced by random ballistic deposition of almost equisized silicate spheres studied using the PROGRA2-surf experiment. The scattering properties were then computed with the RT-CB assuming that the silicate spheres were equisized and that there were a Gaussian particle size distribution. The results were then compared to the measured data and the intensity plot is shown below. The phase functions are normalized to unity at the 40-deg phase angle. The tentative intensity modeling shows good match with the measured data, whereas the polarization modeling shows discrepancies. In summary, the current RT-CB modeling is promising, but more work needs to be carried out, in particular, for modeling the polarization. Acknowledgments. Research supported by European Research Council with Advanced Grant No. 320773 SAEMPL, Scattering and Absorption of ElectroMagnetic waves in ParticuLate media. Computational resources provided by CSC - IT Centre for Science Ltd, Finland.

Study of scattering from turbulence structure generated by propeller with FLUENT

NASA Astrophysics Data System (ADS)

Luo, Gen

2017-07-01

In this article, the turbulence structure generated by a propeller is simulated with the computational fluid dynamics (CFD) software FLUENT. With the method of moments, the backscattering radar cross sections (RCS) of the turbulence structure are calculated. The scattering results can reflect the turbulent intensity of the wave profiles. For the wake turbulence with low rotating speed, the scattering intensity of HH polarization is much smaller than VV polarization at large incident angles. When the turbulence becomes stronger with high rotating speed, the scattering intensity of HH polarization also becomes stronger at large incident angles, which is almost the same with VV polarization. And also, the bistatic scattering of the turbulence structure has the similar situation. These scattering results indicate that the turbulence structure can also give rise to an anomaly compared with traditional sea surface. The study of electromagnetic (EM) scattering from turbulence structure generated by the propeller can help in better understanding of the scattering from different kinds of waves and provide more bases to explain the anomalies of EM scattering from sea surfaces.

Scattering from arbitrarily shaped microstrip patch antennas

NASA Technical Reports Server (NTRS)

Shively, David G.; Deshpande, Manohar D.; Cockrell, Capers R.

1992-01-01

The scattering properties of arbitrarily shaped microstrip patch antennas are examined. The electric field integral equation for a current element on a grounded dielectric slab is developed for a rectangular geometry based on Galerkin's technique with subdomain rooftop basis functions. A shape function is introduced that allows a rectangular grid approximation to the arbitrarily shaped patch. The incident field on the patch is expressed as a function of incidence angle theta(i), phi(i). The resulting system of equations is then solved for the unknown current modes on the patch, and the electromagnetic scattering is calculated for a given angle. Comparisons are made with other calculated results as well as with measurements.

Wave scattering from a periodic dielectric surface for a general angle of incidence

NASA Technical Reports Server (NTRS)

Chuang, S. L.; Kong, J. A.

1982-01-01

Electromagnetic waves scattered from a periodic dielectric and perfectly conducting surface are studied for a general angle of incidence. It is shown that the one-dimensional corrugated surface can be solved by using two scalar functions: the components of the electric and magnetic fields along the row direction of the surface, and appropriate boundary conditions to obtain simple matrix equations. Results are compared to the case where the incident angle wave vector is perpendicular to the row direction. Numerical results demonstrate that energy conservation and reciprocity are obeyed for scattering by sinusoidal surfaces for the general case, which checks the consistency of the formalism.

Remote sensing of Earth terrain

NASA Technical Reports Server (NTRS)

Kong, J. A.

1992-01-01

Research findings are summarized for projects dealing with the following: application of theoretical models to active and passive remote sensing of saline ice; radiative transfer theory for polarimetric remote sensing of pine forest; scattering of electromagnetic waves from a dense medium consisting of correlated Mie scatterers with size distribution and applications to dry snow; variance of phase fluctuations of waves propagating through a random medium; theoretical modeling for passive microwave remote sensing of earth terrain; polarimetric signatures of a canopy of dielectric cylinders based on first and second order vector radiative transfer theory; branching model for vegetation; polarimetric passive remote sensing of periodic surfaces; composite volume and surface scattering model; and radar image classification.

Laser-induced stimulated Raman scattering in the forward direction of a droplet - Comparison of Mie theory with geometrical optics

NASA Technical Reports Server (NTRS)

Srivastava, Vandana; Jarzembski, Maurice A.

1991-01-01

This paper uses Mie theory to treat electromagnetic scattering and to evaluate field enhancement in the forward direction of a small droplet irradiated by a high-energy beam and compares the results of calculations with the field-enhancement evaluation obtained via geometrical optics treatment. Results of this comparison suggest that the field enhancement located at the critical ring region encircling the axis in the forward direction of the droplet can support laser-induced Raman scattering. The results are supported by experimental observations of the interaction of a 120-micron-diam water droplet with a high-energy Nd:YAG laser beam.

Experimental light scattering by ultrasonically controlled small particles - Implications for Planetary Science

NASA Astrophysics Data System (ADS)

Gritsevich, M.; Penttilä, A.; Maconi, G.; Kassamakov, I.; Markkanen, J.; Martikainen, J.; Väisänen, T.; Helander, P.; Puranen, T.; Salmi, A.; Hæggström, E.; Muinonen, K.

2017-09-01

We present the results obtained with our newly developed 3D scatterometer - a setup for precise multi-angular measurements of light scattered by mm- to µm-sized samples held in place by sound. These measurements are cross-validated against the modeled light-scattering characteristics of the sample, i.e., the intensity and the degree of linear polarization of the reflected light, calculated with state-of-the-art electromagnetic techniques. We demonstrate a unique non-destructive approach to derive the optical properties of small grain samples which facilitates research on highly valuable planetary materials, such as samples returned from space missions or rare meteorites.

CELES: CUDA-accelerated simulation of electromagnetic scattering by large ensembles of spheres

NASA Astrophysics Data System (ADS)

Egel, Amos; Pattelli, Lorenzo; Mazzamuto, Giacomo; Wiersma, Diederik S.; Lemmer, Uli

2017-09-01

CELES is a freely available MATLAB toolbox to simulate light scattering by many spherical particles. Aiming at high computational performance, CELES leverages block-diagonal preconditioning, a lookup-table approach to evaluate costly functions and massively parallel execution on NVIDIA graphics processing units using the CUDA computing platform. The combination of these techniques allows to efficiently address large electrodynamic problems (>104 scatterers) on inexpensive consumer hardware. In this paper, we validate near- and far-field distributions against the well-established multi-sphere T-matrix (MSTM) code and discuss the convergence behavior for ensembles of different sizes, including an exemplary system comprising 105 particles.

Cloaking of arbitrarily shaped objects with homogeneous coatings

NASA Astrophysics Data System (ADS)

Forestiere, Carlo; Dal Negro, Luca; Miano, Giovanni

2014-05-01

We present a theory for the cloaking of arbitrarily shaped objects and demonstrate electromagnetic scattering cancellation through designed homogeneous coatings. First, in the small-particle limit, we expand the dipole moment of a coated object in terms of its resonant modes. By zeroing the numerator of the resulting rational function, we accurately predict the permittivity values of the coating layer that abates the total scattered power. Then, we extend the applicability of the method beyond the small-particle limit, deriving the radiation corrections of the scattering-cancellation permittivity within a perturbation approach. Our method permits the design of invisibility cloaks for irregularly shaped devices such as complex sensors and detectors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jimenez-Arguello, Alejandro Marti

The study of the inner structure of hadrons allows us to understand the nature of the interactions between partons, quarks and gluons, described by Quantum Chromodynamics. The elastic scattering reactions, which have been studied in order to measure the nucleon form factors, are included in this frame. The inelastic scattering reactions are also included in this frame, they allow us to obtain information about the nucleon structure thanks to the development of the parton distribution functions (PDFs). While through elastic scattering we can obtain information about the charge distribution of the nucleon, and hence, about the spatial distribution of themore » partons, through inelastic scattering we obtain information about the momentum distributions of partons, by employing the PDFs. However, we can study the exclusive inelastic scattering reactions, such as the Deeply Virtual Compton Scattering (DVCS), wich allow us to access to the spatial and momentum distributions simultaneously. This is possible thanks to the generalized parton distributions (GPDs), which allow us to correlate both types of distributions. The process known as DVCS is the easiest way to access the GPDs. This process can be expressed as the scattering of an electron by a proton by means of a virtual photon with the result of the scattered initial particles plus a real photon. We find a process competing with DVCS known as Bethe-Heitler (BH), in which the real photon is radiated by the lepton rather than the quark. Due to the small cross section of DVCS, of the order of nb, in order to conduct these kind of experiments it is necessary to make use of facilities capable of providing high beam intensities. One of these facilities is the Thomas Jefferson National Accelerator Facility , where the experiment JLab E07-007, "Complete Separation of Virtual Photon and π⁰ Electroproduction Observables of Unpolarized Protons", took place during the months of October to December of 2010. The main goal of this experiment is the isolation of the contribution from the term coming form the DVCS from the interference term, resulting from the BH contribution. This isolation is known as "Rosenbluth Separation". The work presented in this thesis focuses on the analysis of the data stored by the electromagnetic calorimeter, employed for the detection of real photons. There is also a a theoretical introduction to the study of the nucleon structure, reviewing the concepts of form factors and parton distributions through elastic and inelastic processes. The computation of the photon leptoproduction cross section is described in detail, as well as the goals of experiment E07-007. This thesis also describes the analysis of the data stored by the electromagnetic calorimeter, with the purpose of obtaining the kinematic variables of the real photons resulting from DVCS reactions. Finally, it describes the selection of events from stored data, the applied cuts to kinematical variables and the background subtraction. Also, the process of extraction of the necessary observables for computing the photon leptoproduction cross section is described, along with the main steps followed to perform the Monte Carlo simulation used in this computation. The resulting cross sections are shown at the end of this thesis.« less

Scattering Cross Section of Sound Waves by the Modal Element Method

NASA Technical Reports Server (NTRS)

Baumeister, Kenneth J.; Kreider, Kevin L.

1994-01-01

#he modal element method has been employed to determine the scattered field from a plane acoustic wave impinging on a two dimensional body. In the modal element method, the scattering body is represented by finite elements, which are coupled to an eigenfunction expansion representing the acoustic pressure in the infinite computational domain surrounding the body. The present paper extends the previous work by developing the algorithm necessary to calculate the acoustics scattering cross section by the modal element method. The scattering cross section is the acoustical equivalent to the Radar Cross Section (RCS) in electromagnetic theory. Since the scattering cross section is evaluated at infinite distance from the body, an asymptotic approximation is used in conjunction with the standard modal element method. For validation, the scattering cross section of the rigid circular cylinder is computed for the frequency range 0.1 is less than or equal to ka is less than or equal to 100. Results show excellent agreement with the analytic solution.

Polarimetric scattering behavior of materials at terahertz frequencies

NASA Astrophysics Data System (ADS)

DiGiovanni, David Anthony

Terahertz spectroscopic techniques have long been used to characterize the electromagnetic behavior of materials for use in radar, astronomy, and remote sensing applications. Spectroscopic information is valuable, but additional information about materials is present in the polarization of the scattered radiation. This thesis has investigated the polarimetric scattering behavior of various rough dielectric and metallic materials from 100 GHz to 1.55 THz. Common building materials and terrain, such as sand, gravel, soil, concrete, and roofing shingles, were studied. In order to obtain a better understanding of basic rough surface scattering phenomenology in this region of the spectrum, roughened metal and plastic samples were studied as well. The scattering behavior of these materials was studied as a function of incident angle, roughness, frequency, and polarization. Theoretical scattering models were used to compare measured results to theoretical predictions. Good agreement was observed between scattering measurements and theoretical predictions based on the small perturbation theory for the roughened metal surfaces. However, a substantial disagreement was observed for the rough dielectric surfaces and is discussed.

Memory sparing, fast scattering formalism for rigorous diffraction modeling

NASA Astrophysics Data System (ADS)

Iff, W.; Kämpfe, T.; Jourlin, Y.; Tishchenko, A. V.

2017-07-01

The basics and algorithmic steps of a novel scattering formalism suited for memory sparing and fast electromagnetic calculations are presented. The formalism, called ‘S-vector algorithm’ (by analogy with the known scattering-matrix algorithm), allows the calculation of the collective scattering spectra of individual layered micro-structured scattering objects. A rigorous method of linear complexity is applied to model the scattering at individual layers; here the generalized source method (GSM) resorting to Fourier harmonics as basis functions is used as one possible method of linear complexity. The concatenation of the individual scattering events can be achieved sequentially or in parallel, both having pros and cons. The present development will largely concentrate on a consecutive approach based on the multiple reflection series. The latter will be reformulated into an implicit formalism which will be associated with an iterative solver, resulting in improved convergence. The examples will first refer to 1D grating diffraction for the sake of simplicity and intelligibility, with a final 2D application example.

The electromagnetic modeling of thin apertures using the finite-difference time-domain technique

NASA Technical Reports Server (NTRS)

Demarest, Kenneth R.

1987-01-01

A technique which computes transient electromagnetic responses of narrow apertures in complex conducting scatterers was implemented as an extension of previously developed Finite-Difference Time-Domain (FDTD) computer codes. Although these apertures are narrow with respect to the wavelengths contained within the power spectrum of excitation, this technique does not require significantly more computer resources to attain the increased resolution at the apertures. In the report, an analytical technique which utilizes Babinet's principle to model the apertures is developed, and an FDTD computer code which utilizes this technique is described.

A new metamaterial-based wideband rectangular invisibility cloak

NASA Astrophysics Data System (ADS)

Islam, S. S.; Hasan, M. M.; Faruque, M. R. I.

2018-02-01

A new metamaterial-based wideband electromagnetic rectangular cloak is being introduced in this study. The metamaterial unit cell shows sharp transmittances in the C- and X-bands and displays wideband negative effective permittivity region there. The metamaterial unit cell was then applied in designing a rectangular-shaped electromagnetic cloak. The scattering reduction technique was adopted for the cloaking operation. The cloak operates in the certain portion of C-and X-bands that covers more than 4 GHz bandwidth region. The experimental results were provided as well for the metamaterial and the cloak.

Theoretical investigation of resonance frequencies in long wavelength electromagnetic wave scattering process from plasma prolate and oblate spheroids placed in a dielectric layer

NASA Astrophysics Data System (ADS)

Ahmadizadeh, Y.; Jazi, B.; Abdoli-Arani, A.

2014-01-01

Response of a prolate spheroid plasma and/or an oblate spheroid plasma in presence of long wavelength electromagnetic wave has been studied. The resonance frequencies of these objects are obtained and it is found that they reduce to the resonance frequency of spherical cold plasma. Moreover, the resonant frequencies of prolate spheroid plasma and oblate spheroid plasma covered by a dielectric are investigated as well. Furthermore, their dependency on dielectric permittivity and geometry dimensions is simulated.

Numerical and Experimental Investigation on Electromagnetic Attenuation by Semi-Ellipsoidal Shaped Plasma

NASA Astrophysics Data System (ADS)

He, Xiang; Chen, Jianping; Zhang, Yachun; Chen, Yudong; Zeng, Xiaojun; Tang, Chunmei

2015-10-01

Some reports presented that the radar cross section (RCS) from the radar antenna of military airplanes can be reduced by using a low-temperature plasma screen. This paper gives a numerical and experimental analysis of this RCS-reduction method. The shape of the plasma screen was designed as a semi-ellipsoid in order to make full use of the space in the radar dome. In simulations, we discussed the scattering of the electromagnetic (EM) wave by a perfect electric conductor (PEC) covered with this plasma screen using the finite-difference-time-domain (FDTD) method. The variations of their return loss as a function of wave frequency, plasma density profile, and collision frequency were presented. In the experiments, a semi-ellipsoidal shaped plasma screen was produced. Electromagnetic attenuation of 1.5 GHz EM wave was measured for a radio frequency (RF) power of 5 kW at an argon pressure of 200-1150 Pa. A good agreement is found between simulated and experimental results. It can be confirmed that the plasma screen is useful in applications for stealth of radar antenna. supported by National Natural Science Foundation of China (No. 51107033) and the Fundamental Research Funds for the Central Universities, China (No. 2013B33614)

Acoustic and electromagnetic wave interaction in the detection and identification of buried objects

NASA Astrophysics Data System (ADS)

Lawrence, Daniel Edward

2002-09-01

In order to facilitate the development of a hybrid acoustic and electromagnetic (EM) system for buried object detection, a number of analytical solutions and a novel numerical technique are developed to analyze the complex interaction between acoustic and EM scattering. The essence of the interaction lies in the fact that identifiable acoustic properties of an object, such as acoustic resonances, can be observed in the scattered EM Doppler spectrum. Using a perturbation approach, analytical solutions are derived for the EM scattering from infinitely long circular cylinders, both metallic and dielectric, under acoustic vibration in a homogeneous background medium. Results indicate that both the shape variation and dielectric constant contribute to the scattered EM Doppler spectrum. To model the effect of a cylinder beneath an acoustically excited half-space, a new analytical solution is presented for EM scattering from a cylinder beneath a slightly rough surface. The solution is achieved by using plane-wave expansion of the fields and an iterative technique to account for the multiple interactions between the cylinder and rough surface. Following a similar procedure, a novel solution for elastic-wave scattering from a solid cylinder embedded in a solid half-space is developed and used to calculate the surface displacement. Simulations indicate that only a finite range of spatial surface frequencies, corresponding to surface roughness on the order of the EM wavelength; affect the EM scattering from buried objects and suggest that object detection can be improved if the acoustic excitation induces surface roughness outside this range. To extend the study to non-canonical scenarios, a novel numerical approach is introduced in which time-varying impedance boundary conditions (IBCs) are used in conjunction with the method of moments (MoM) to model the EM scattering from vibrating metallic objects of arbitrary shape. It is shown that the standard IBC provides a first order solution for TM polarization, but a second order IBC is needed for TE polarization. The crucial factor in the calculation of the potentially small Doppler components is that the time-varying nature of the cylinder boundary, contained within the surface impedance expressions, can be isolated from the unperturbed terms in the scattered field.

Full wave two-dimensional modeling of scattering and inverse scattering for layered rough surfaces with buried objects

NASA Astrophysics Data System (ADS)

Kuo, Chih-Hao

Efficient and accurate modeling of electromagnetic scattering from layered rough surfaces with buried objects finds applications ranging from detection of landmines to remote sensing of subsurface soil moisture. The formulation of a hybrid numerical/analytical solution to electromagnetic scattering from layered rough surfaces is first presented in this dissertation. The solution to scattering from each rough interface is sought independently based on the extended boundary condition method (EBCM), where the scattered fields of each rough interface are expressed as a summation of plane waves and then cast into reflection/transmission matrices. To account for interactions between multiple rough boundaries, the scattering matrix method (SMM) is applied to recursively cascade reflection and transmission matrices of each rough interface and obtain the composite reflection matrix from the overall scattering medium. The validation of this method against the Method of Moments (MoM) and Small Perturbation Method (SPM) is addressed and the numerical results which investigate the potential of low frequency radar systems in estimating deep soil moisture are presented. Computational efficiency of the proposed method is also discussed. In order to demonstrate the capability of this method in modeling coherent multiple scattering phenomena, the proposed method has been employed to analyze backscattering enhancement and satellite peaks due to surface plasmon waves from layered rough surfaces. Numerical results which show the appearance of enhanced backscattered peaks and satellite peaks are presented. Following the development of the EBCM/SMM technique, a technique which incorporates a buried object in layered rough surfaces by employing the T-matrix method and the cylindrical-to-spatial harmonics transformation is proposed. Validation and numerical results are provided. Finally, a multi-frequency polarimetric inversion algorithm for the retrieval of subsurface soil properties using VHF/UHF band radar measurements is devised. The top soil dielectric constant is first determined using an L-band inversion algorithm. For the retrieval of subsurface properties, a time-domain inversion technique is employed together with a parameter optimization for the pulse shape of time delay echoes from VHF/UHF band radar observations. Numerical studies to investigate the accuracy of the proposed inversion technique in presence of errors are addressed.

Light effects on the multicellular magnetotactic prokaryote 'Candidatus Magnetoglobus multicellularis' are cancelled by radiofrequency fields: the involvement of radical pair mechanisms.

PubMed

de Melo, Roger Duarte; Acosta-Avalos, Daniel

2017-02-01

'Candidatus Magnetoglobus multicellularis' is the most studied multicellular magnetotactic prokaryote. It presents a light-dependent photokinesis: green light decreases the translation velocity whereas red light increases it, in comparison to blue and white light. The present article shows that radio-frequency electromagnetic fields cancel the light effect on photokinesis. The frequency to cancel the light effect corresponds to the Zeeman resonance frequency (DC magnetic field of 4 Oe and radio-frequency of 11.5 MHz), indicating the involvement of a radical pair mechanism. An analysis of the orientation angle relative to the magnetic field direction shows that radio-frequency electromagnetic fields disturb the swimming orientation when the microorganisms are illuminated with red light. The analysis also shows that at low magnetic fields (1.6 Oe) the swimming orientation angles are well scattered around the magnetic field direction, showing that magnetotaxis is not efficiently in the swimming orientation to the geomagnetic field. The results do not support cryptochrome as being the responsible chromophore for the radical pair mechanism and perhaps two different chromophores are necessary to explain the radio-frequency effects.

Electromagnetic Scattering from Realistic Targets

NASA Technical Reports Server (NTRS)

Lee, Shung- Wu; Jin, Jian-Ming

1997-01-01

The general goal of the project is to develop computational tools for calculating radar signature of realistic targets. A hybrid technique that combines the shooting-and-bouncing-ray (SBR) method and the finite-element method (FEM) for the radiation characterization of microstrip patch antennas in a complex geometry was developed. In addition, a hybridization procedure to combine moment method (MoM) solution and the SBR method to treat the scattering of waveguide slot arrays on an aircraft was developed. A list of journal articles and conference papers is included.

Forward Helion Scattering and Neutron Polarization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buttimore, N. H.

The elastic scattering of spin half helium-3 nuclei at small angles can show a sufficiently large analyzing power to enable the level of helion polarization to be evaluated. As the helion to a large extent inherits the polarization of its unpaired neutron the asymmetry observed in helion collisions can be transformed into a measurement of the polarization of its constituent neutron. Neutron polarimetry therefore relies upon understanding the spin dependence of the electromagnetic and hadronic interactions in the region of interference where there is an optimal analyzing power.

Long-Range Correlations Between Transmitted and Reected Fluxes of Electromagnetic Waves

NASA Astrophysics Data System (ADS)

Gorodnichev, E. E.; Kuzovlev, A. I.; Rogozkin, D. B.

2017-12-01

We study the long-range spatial correlations between intensity fluctuations in speckles formed by multiply scattered light. The correlation function between intensity fluctuations at the opposite boundaries of the slab are analyzed under the conditions of circular polarization memory. It shown that, until the scattered light is depolarized completely, the polarization and scalar contributions to the correlation function are of the same order of magnitude. As the slab thickness increases, their ratio falls off in inverse proportion to the thickness.

Laser modified processes: bremsstrahlung and inelastic photon atom scattering

NASA Astrophysics Data System (ADS)

Budriga, Olimpia; Dondera, Mihai; Florescu, Viorica

2007-08-01

We consider the influence of a low-frequency monochromatic external electromagnetic field (the laser) on two basic atomic processes: electron Coulomb bremsstrahlung and inelastic photon scattering on an electron bound in the ground state of a hydrogenic atom. We briefly describe the approximations adopted and illustrate in figures how the laser parameters modify the shape of the differential cross-sections and extend the energy domain for emitted electrons, due to simultaneous absorption or emission of a large number (hundreds) of laser photons.

Multiple scattering in particulate planetary surfaces

NASA Astrophysics Data System (ADS)

Muinonen, Karri; Peltoniemi, Jouni; Markkanen, Johannes; Penttilä, Antti; Videen, Gorden

2015-08-01

There are two ubiquitous phenomena observed at small solar phase angles (the Sun-Object-Observer angle) from, for example, asteroids and transneptunian objects. First, a nonlinear increase of brightness is observed toward the zero phase angle in the magnitude scale that is commonly called the opposition effect. Second, the scattered light is observed to be partially linearly polarized parallel to the Sun-Object-Observer plane that iscommonly called the negative polarization surge.The observations can be interpreted using a radiative-transfer coherent-backscattering Monte Carlo method (RT-CB, Muinonen 2004) that makes use of a so-called phenomenological fundamental single scatterer (Muinonen and Videen 2012). For the validity of RT-CB, see Muinonen et al. (2012). The method can allow us to put constraints on the size, shape, and refractive index of the fundamental scatterers.In the present work, we extend the RT-CB method for the specific case of a macroscopic medium of electric dipole scatterers. For the computation of the interactions, the far-field approximation inherent in the RT-CB method is replaced by an exact treatment, allowing us to account for, e.g., the so-called near-field effects. The present method constitutes the first milestone in the development of a multiple-scattering method, where the so-called ladder and maximally crossed cyclical diagrams of the multiple electromagnetic interactions are rigorously computed. We expect to utilize the new methods in the spectroscopic, photometric, and polarimetric studies of asteroids, as well as in the interpretation of radar echoes from small Solar System bodies.Acknowledgments. The research is funded by the ERC Advanced Grant No 320773 entitled Scattering and Absorption of Electromagnetic Waves in Particulate Media (SAEMPL).K. Muinonen, Waves in Random Media 14, 365 (2004).K. Muinonen, K., and G. Videen, JQSRT 113, 2385 (2012).K. Muinonen, M. I. Mishchenko, J. M. Dlugach, E. Zubko, A. Penttilä,and G. Videen, ApJ 760, 118 (2012).

Ultrasound-aided high-resolution biophotonic imaging

NASA Astrophysics Data System (ADS)

Wang, Lihong V.

2003-10-01

We develop novel biophotonic imaging for early-cancer detection, a grand challenge in cancer research, using nonionizing electromagnetic and ultrasonic waves. Unlike ionizing x-ray radiation, nonionizing electromagnetic waves such as optical waves are safe for biomedical applications and reveal new contrast mechanisms and functional information. For example, our spectroscopic oblique-incidence reflectometry can detect skin cancers based on functional hemoglobin parameters and cell nuclear size with 95% accuracy. Unfortunately, electromagnetic waves in the nonionizing spectral region do not penetrate biological tissue in straight paths as do x-rays. Consequently, high-resolution tomography based on nonionizing electromagnetic waves alone, as demonstrated by our Mueller optical coherence tomography, is limited to superficial tissue imaging. Ultrasonic imaging, on the contrary, furnishes good imaging resolution but has poor contrast in early-stage tumors and has strong speckle artifacts as well. We developed ultrasound-mediated imaging modalities by combining electromagnetic and ultrasonic waves synergistically. The hybrid modalities yield speckle-free electromagnetic-contrast at ultrasonic resolution in relatively large biological tissue. In ultrasound-modulated (acousto)-optical tomography, a focused ultrasonic wave encodes diffuse laser light in scattering biological tissue. In photo-acoustic (thermo-acoustic) tomography, a low-energy laser (RF) pulse induces ultrasonic waves in biological tissue due to thermoelastic expansion.

Applied mathematical problems in modern electromagnetics

NASA Astrophysics Data System (ADS)

Kriegsman, Gregory

1994-05-01

We have primarily investigated two classes of electromagnetic problems. The first contains the quantitative description of microwave heating of dispersive and conductive materials. Such problems arise, for example, when biological tissue are exposed, accidentally or purposefully, to microwave radiation. Other instances occur in ceramic processing, such as sintering and microwave assisted chemical vapor infiltration and other industrial drying processes, such as the curing of paints and concrete. The second class characterizes the scattering of microwaves by complex targets which possess two or more disparate length and/or time scales. Spatially complex scatterers arise in a variety of applications, such as large gratings and slowly changing guiding structures. The former are useful in developing microstrip energy couplers while the later can be used to model anatomical subsystems (e.g., the open guiding structure composed of two legs and the adjoining lower torso). Temporally complex targets occur in applications involving dispersive media whose relaxation times differ by orders of magnitude from thermal and/or electromagnetic time scales. For both cases the mathematical description of the problems gives rise to complicated ill-conditioned boundary value problems, whose accurate solutions require a blend of both asymptotic techniques, such as multiscale methods and matched asymptotic expansions, and numerical methods incorporating radiation boundary conditions, such as finite differences and finite elements.

COSMIC monthly progress report

NASA Technical Reports Server (NTRS)

1993-01-01

Activities of the Computer Software Management and Information Center (COSMIC) are summarized for the month of August, 1993. Tables showing the current inventory of programs available from COSMIC are presented and program processing and evaluation activities are discussed. Ten articles were prepared for publication in the NASA Tech Brief Journal. These articles (included in this report) describe the following software items: (1) MOM3D - A Method of Moments Code for Electromagnetic Scattering (UNIX Version); (2) EM-Animate - Computer Program for Displaying and Animating the Steady-State Time-Harmonic Electromagnetic Near Field and Surface-Current Solutions; (3) MOM3D - A Method of Moments Code for Electromagnetic Scattering (IBM PC Version); (4) M414 - MIL-STD-414 Variable Sampling Procedures Computer Program; (5) MEDOF - Minimum Euclidean Distance Optimal Filter; (6) CLIPS 6.0 - C Language Integrated Production System, Version 6.0 (Macintosh Version); (7) CLIPS 6.0 - C Language Integrated Production System, Version 6.0 (IBM PC Version); (8) CLIPS 6.0 - C Language Integrated Production System, Version 6.0 (UNIX Version); (9) CLIPS 6.0 - C Language Integrated Production System, Version 6.0 (DEC VAX VMS Version); and (10) TFSSRA - Thick Frequency Selective Surface with Rectangular Apertures. Activities in the areas of marketing, customer service, benefits identification, maintenance and support, and dissemination are also described along with a budget summary.

ILS Localizer Performance Study for Dallas/Fort Worth Airport, Part 2

DOT National Transportation Integrated Search

1974-02-01

The Transportation Systems Center electromagnetic scattering model was used to predict the course deviation indication (CDI) at the Dallas/Fort Worth Airport in the presence of several derogating structures in the report FAA-RD-72-96 'ILS Localizer P...

Accurate Characterization of Winter Precipitation Using In-Situ Instrumentation, CSU-CHILL Radar, and Advanced Scattering Methods

NASA Astrophysics Data System (ADS)

Newman, A. J.; Notaros, B. M.; Bringi, V. N.; Kleinkort, C.; Huang, G. J.; Kennedy, P.; Thurai, M.

2015-12-01

We present a novel approach to remote sensing and characterization of winter precipitation and modeling of radar observables through a synergistic use of advanced in-situ instrumentation for microphysical and geometrical measurements of ice and snow particles, image processing methodology to reconstruct complex particle three-dimensional (3D) shapes, computational electromagnetics to analyze realistic precipitation scattering, and state-of-the-art polarimetric radar. Our in-situ measurement site at the Easton Valley View Airport, La Salle, Colorado, shown in the figure, consists of two advanced optical imaging disdrometers within a 2/3-scaled double fence intercomparison reference wind shield, and also includes PLUVIO snow measuring gauge, VAISALA weather station, and collocated NCAR GPS advanced upper-air system sounding system. Our primary radar is the CSU-CHILL radar, with a dual-offset Gregorian antenna featuring very high polarization purity and excellent side-lobe performance in any plane, and the in-situ instrumentation site being very conveniently located at a range of 12.92 km from the radar. A multi-angle snowflake camera (MASC) is used to capture multiple different high-resolution views of an ice particle in free-fall, along with its fall speed. We apply a visual hull geometrical method for reconstruction of 3D shapes of particles based on the images collected by the MASC, and convert these shapes into models for computational electromagnetic scattering analysis, using a higher order method of moments. A two-dimensional video disdrometer (2DVD), collocated with the MASC, provides 2D contours of a hydrometeor, along with the fall speed and other important parameters. We use the fall speed from the MASC and the 2DVD, along with state parameters measured at the Easton site, to estimate the particle mass (Böhm's method), and then the dielectric constant of particles, based on a Maxwell-Garnet formula. By calculation of the "particle-by-particle" scattering matrices over large time intervals using the in-situ measured data, we obtain, simultaneously, all polarimetric radar observables, which are then compared and analyzed against measurements by the CHILL Radar. We present and discuss results from several interesting events observed during the 2014/2015 winter campaign.

Scattering and cloaking of binary hyper-particles in metamaterials.

PubMed

Alexopoulos, A; Yau, K S B

2010-09-13

We derive the d-dimensional scattering cross section for homogeneous and composite hyper-particles inside a metamaterial. The polarizability of the hyper-particles is expressed in multi-dimensional form and is used in order to examine various scattering characteristics. We introduce scattering bounds that display interesting results when d --> ∞ and in particular consider the special limit of hyper-particle cloaking in some detail. We demonstrate cloaking via resonance for homogeneous particles and show that composite hyper-particles can be used in order to obtain electromagnetic cloaking with either negative or all positive constitutive parameters respectively. Our approach not only considers cloaking of particles of integer dimension but also particles with non-integer dimension such as fractals. Theoretical results are compared to full-wave numerical simulations for two interacting hyper-particles in a medium.

Stimulated Raman scattering of sub-millimeter waves in bismuth

NASA Astrophysics Data System (ADS)

Kumar, Pawan; Tripathi, V. K.

2007-12-01

A high-power sub-millimeter wave propagating through bismuth, a semimetal with non-spherical energy surfaces, parametrically excites a space-charge mode and a back-scattered electromagnetic wave. The free carrier density perturbation associated with the space-charge wave couples with the oscillatory velocity due to the pump to derive the scattered wave. The scattered and pump waves exert a pondermotive force on electrons and holes, driving the space-charge wave. The collisional damping of the decay waves determines the threshold for the parametric instability. The threshold intensity for 20 μm wavelength pump turns out to be ˜2×1012 W/cm2. Above the threshold, the growth rate scales increase with ωo, attain a maximum around ωo=6.5ωp, and, after this, falls off.

Asymmetric micro-Doppler frequency comb generation via magnetoelectric coupling

NASA Astrophysics Data System (ADS)

Filonov, Dmitry; Steinberg, Ben Z.; Ginzburg, Pavel

2017-06-01

Electromagnetic scattering from moving bodies, being an inherently time-dependent phenomenon, gives rise to a generation of new frequencies, which can be used to characterize the motion. Whereas an ordinary motion along a linear path produces a constant Doppler shift, an accelerated scatterer can generate a micro-Doppler frequency comb. The spectra produced by rotating objects were studied and observed in a bistatic lock-in detection scheme. The internal geometry of a scatterer was shown to determine the spectrum, and the degree of structural asymmetry was suggested to be identified via signatures in the micro-Doppler comb. In particular, hybrid magnetoelectric particles, showing an ultimate degree of asymmetry in forward and backward scattering directions, were investigated. It was shown that the comb in the backward direction has signatures at the fundamental rotation frequency and its odd harmonics, whereas the comb of the forward scattered field has a prevailing peak at the doubled frequency and its multiples. Additional features of the comb were shown to be affected by the dimensions of the particle and by the strength of the magnetoelectric coupling. Experimental verification was performed with a printed circuit board antenna based on a wire and a split ring, while the structure was illuminated at a 2 GHz carrier frequency. Detailed analysis of micro-Doppler combs enables remote detection of asymmetric features of distant objects and could find use in a span of applications, including stellar radiometry and radio identification.

Numerical analysis of dysplasia-associated changes in depth-dependent light scattering profile of cervical epithelium

NASA Astrophysics Data System (ADS)

Arifler, Dizem; MacAulay, Calum; Follen, Michele; Guillaud, Martial

2013-06-01

Dysplastic progression is known to be associated with changes in morphology and internal structure of cells. A detailed assessment of the influence of these changes on cellular scattering response is needed to develop and optimize optical diagnostic techniques. In this study, we first analyzed a set of quantitative histopathologic images from cervical biopsies and we obtained detailed information on morphometric and photometric features of segmented epithelial cell nuclei. Morphometric parameters included average size and eccentricity of the best-fit ellipse. Photometric parameters included optical density measures that can be related to dielectric properties and texture characteristics of the nuclei. These features enabled us to construct realistic three-dimensional computational models of basal, parabasal, intermediate, and superficial cell nuclei that were representative of four diagnostic categories, namely normal (or negative for dysplasia), mild dysplasia, moderate dysplasia, and severe dysplasia or carcinoma in situ. We then employed the finite-difference time-domain method, a popular numerical tool in electromagnetics, to compute the angle-resolved light scattering properties of these representative models. Results indicated that a high degree of variability can characterize a given diagnostic category, but scattering from moderately and severely dysplastic or cancerous nuclei was generally observed to be stronger compared to scattering from normal and mildly dysplastic nuclei. Simulation results also pointed to significant intensity level variations among different epithelial depths. This suggests that intensity changes associated with dysplastic progression need to be analyzed in a depth-dependent manner.

Scattering of Gaussian Beams by Disordered Particulate Media

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Dlugach, Janna M.

2016-01-01

A frequently observed characteristic of electromagnetic scattering by a disordered particulate medium is the absence of pronounced speckles in angular patterns of the scattered light. It is known that such diffuse speckle-free scattering patterns can be caused by averaging over randomly changing particle positions and/or over a finite spectral range. To get further insight into the possible physical causes of the absence of speckles, we use the numerically exact superposition T-matrix solver of the Maxwell equations and analyze the scattering of plane-wave and Gaussian beams by representative multi-sphere groups. We show that phase and amplitude variations across an incident Gaussian beam do not serve to extinguish the pronounced speckle pattern typical of plane-wave illumination of a fixed multi-particle group. Averaging over random particle positions and/or over a finite spectral range is still required to generate the classical diffuse speckle-free regime.

A Persistent Feature of Multiple Scattering of Waves in the Time-Domain: A Tutorial

NASA Technical Reports Server (NTRS)

Lock, James A.; Mishchenko, Michael I.

2015-01-01

The equations for frequency-domain multiple scattering are derived for a scalar or electromagnetic plane wave incident on a collection of particles at known positions, and in the time-domain for a plane wave pulse incident on the same collection of particles. The calculation is carried out for five different combinations of wave types and particle types of increasing geometrical complexity. The results are used to illustrate and discuss a number of physical and mathematical characteristics of multiple scattering in the frequency- and time-domains. We argue that frequency-domain multiple scattering is a purely mathematical construct since there is no temporal sequencing information in the frequency-domain equations and since the multi-particle path information can be dispelled by writing the equations in another mathematical form. However, multiple scattering becomes a definite physical phenomenon in the time-domain when the collection of particles is illuminated by an appropriately short localized pulse.

On Born approximation in black hole scattering

NASA Astrophysics Data System (ADS)

Batic, D.; Kelkar, N. G.; Nowakowski, M.

2011-12-01

A massless field propagating on spherically symmetric black hole metrics such as the Schwarzschild, Reissner-Nordström and Reissner-Nordström-de Sitter backgrounds is considered. In particular, explicit formulae in terms of transcendental functions for the scattering of massless scalar particles off black holes are derived within a Born approximation. It is shown that the conditions on the existence of the Born integral forbid a straightforward extraction of the quasi normal modes using the Born approximation for the scattering amplitude. Such a method has been used in literature. We suggest a novel, well defined method, to extract the large imaginary part of quasinormal modes via the Coulomb-like phase shift. Furthermore, we compare the numerically evaluated exact scattering amplitude with the Born one to find that the approximation is not very useful for the scattering of massless scalar, electromagnetic as well as gravitational waves from black holes.

Scattering suppression from arbitrary objects in spatially dispersive layered metamaterials

NASA Astrophysics Data System (ADS)

Shalin, Alexander S.; Ginzburg, Pavel; Orlov, Alexey A.; Iorsh, Ivan; Belov, Pavel A.; Kivshar, Yuri S.; Zayats, Anatoly V.

2015-03-01

Concealing objects by making them invisible to an external electromagnetic probe is coined by the term "cloaking." Cloaking devices, having numerous potential applications, are still facing challenges in realization, especially in the visible spectral range. In particular, inherent losses and extreme parameters of metamaterials required for the cloak implementation are the limiting factors. Here, we numerically demonstrate nearly perfect suppression of scattering from arbitrary-shaped objects in spatially dispersive metamaterial acting as an alignment-free concealing cover. We consider a realization of a metamaterial as a metal-dielectric multilayer and demonstrate suppression of scattering from an arbitrary object in forward and backward directions with perfectly preserved wave fronts and less than 10% absolute intensity change, despite spatial dispersion effects present in the composite metamaterial. Beyond the usual scattering suppression applications, the proposed configuration may be used for a simple realization of scattering-free detectors and sensors.

Wave-Kinetic Simulations of the Nonlinear Generation of Electromagnetic VLF Waves through Velocity Ring Instabilities

NASA Astrophysics Data System (ADS)

Ganguli, G.; Crabtree, C. E.; Rudakov, L.; Mithaiwala, M.

2014-12-01

Velocity ring instabilities are a common naturally occuring magnetospheric phenomenon that can also be generated by man made ionospheric experiments. These instabilities are known to generate lower-hybrid waves, which generally cannot propagte out of the source region. However, nonlinear wave physics can convert these linearly driven electrostatic lower-hybrid waves into electromagnetic waves that can escape the source region. These nonlinearly generated waves can be an important source of VLF turbulence that controls the trapped electron lifetime in the radiation belts. We develop numerical solutions to the wave-kinetic equation in a periodic box including the effects of nonlinear (NL) scattering (nonlinear Landau damping) of Lower-hybrid waves giving the evolution of the wave-spectra in wavenumber space. Simultaneously we solve the particle diffusion equation of both the background plasma particles and the ring ions, due to both linear and nonlinear Landau resonances. At initial times for cold ring ions, an electrostatic beam mode is excited, while the kinetic mode is stable. As the instability progresses the ring ions heat, the beam mode is stabilized, and the kinetic mode destabilizes. When the amplitude of the waves becomes sufficient the lower-hybrid waves are scattered (by either nearly unmagnetized ions or magnetized electrons) into electromagnetic magnetosonic waves [Ganguli et al 2010]. The effect of NL scattering is to limit the amplitude of the waves, slowing down the quasilinear relaxation time and ultimately allowing more energy from the ring to be liberated into waves [Mithaiwala et al. 2011]. The effects of convection out of the instability region are modeled, additionally limiting the amplitude of the waves, allowing further energy to be liberated from the ring [Scales et al., 2012]. Results are compared to recent 3D PIC simulations [Winske and Duaghton 2012].

Studies of the ionospheric turbulence excited by the fourth gyroharmonic at HAARP

NASA Astrophysics Data System (ADS)

Najmi, A.; Milikh, G.; Yampolski, Y. M.; Koloskov, A. V.; Sopin, A. A.; Zalizovski, A.; Bernhardt, P.; Briczinski, S.; Siefring, C.; Chiang, K.; Morton, Y.; Taylor, S.; Mahmoudian, A.; Bristow, W.; Ruohoniemi, M.; Papadopoulos, K.

2015-08-01

A study is presented of artificial ionospheric turbulence (AIT) induced by HF heating at High Frequency Active Auroral Research Program (HAARP) using frequencies close to the fourth electron gyroharmonic, in a broad range of radiated powers and using a number of different diagnostics. The diagnostics include GPS scintillations, ground-based stimulated electromagnetic emission (SEE), the HAARP ionosonde, Kodiak radar, and signals received at the Ukrainian Antarctic Station (UAS). The latter allowed analysis of waves scattered by the AIT into the ionospheric waveguide along Earth's terminator, 15.6 mm from the HAARP facility. For the first time, the amplitudes of two prominent SEE features, the downshifted maximum and broad upshifted maximum, were observed to saturate at ~50% of the maximum HAARP effective radiated power. Nonlinear effects in slant total electron content, SEE, and signals received at UAS at different transmitted frequencies and intensities of the pump wave were observed. The correlations between the data from different detectors demonstrate that the scattered waves reach UAS by the waveguide along the Earth's terminator, and that they were injected into the waveguide by scattering off of artificial striations produced by AIT above HAARP, rather than via direct injection from sidelobe radiation.

Applications of the conjugate gradient FFT method in scattering and radiation including simulations with impedance boundary conditions

NASA Technical Reports Server (NTRS)

Barkeshli, Kasra; Volakis, John L.

1991-01-01

The theoretical and computational aspects related to the application of the Conjugate Gradient FFT (CGFFT) method in computational electromagnetics are examined. The advantages of applying the CGFFT method to a class of large scale scattering and radiation problems are outlined. The main advantages of the method stem from its iterative nature which eliminates a need to form the system matrix (thus reducing the computer memory allocation requirements) and guarantees convergence to the true solution in a finite number of steps. Results are presented for various radiators and scatterers including thin cylindrical dipole antennas, thin conductive and resistive strips and plates, as well as dielectric cylinders. Solutions of integral equations derived on the basis of generalized impedance boundary conditions (GIBC) are also examined. The boundary conditions can be used to replace the profile of a material coating by an impedance sheet or insert, thus, eliminating the need to introduce unknown polarization currents within the volume of the layer. A general full wave analysis of 2-D and 3-D rectangular grooves and cavities is presented which will also serve as a reference for future work.

Evidence for light-by-light scattering in heavy-ion collisions with the ATLAS detector at the LHC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aaboud, M.; Aad, G.; Abbott, B.

Light-by-light scattering (γγ → γγ) is a quantum-mechanical process that is forbidden in the classical theory of electrodynamics. This reaction is accessible at the Large Hadron Collider thanks to the large electromagnetic field strengths generated by ultra-relativistic colliding lead ions. Using 480 μb -1 of lead–lead collision data recorded at a centre-of-mass energy per nucleon pair of 5.02 TeV by the ATLAS detector, here we report evidence for light-by-light scattering. A total of 13 candidate events were observed with an expected background of 2.6 ± 0.7 events. After background subtraction and analysis corrections, the fiducial cross-section of the process Pbmore » + Pb (γγ) → Pb(*) + Pb(*)γγ, for photon transverse energy E T > 3 GeV, photon absolute pseudorapidity |η| < 2.4, diphoton invariant mass greater than 6 GeV, diphoton transverse momentum lower than 2 GeV and diphoton acoplanarity below 0.01, is measured to be 70 ± 24 (stat.) ± 17 (syst.) nb, which is in agreement with the standard model predictions.« less

Evidence for light-by-light scattering in heavy-ion collisions with the ATLAS detector at the LHC

DOE PAGES

Aaboud, M.; Aad, G.; Abbott, B.; ...

2017-08-14

Light-by-light scattering (γγ → γγ) is a quantum-mechanical process that is forbidden in the classical theory of electrodynamics. This reaction is accessible at the Large Hadron Collider thanks to the large electromagnetic field strengths generated by ultra-relativistic colliding lead ions. Using 480 μb -1 of lead–lead collision data recorded at a centre-of-mass energy per nucleon pair of 5.02 TeV by the ATLAS detector, here we report evidence for light-by-light scattering. A total of 13 candidate events were observed with an expected background of 2.6 ± 0.7 events. After background subtraction and analysis corrections, the fiducial cross-section of the process Pbmore » + Pb (γγ) → Pb(*) + Pb(*)γγ, for photon transverse energy E T > 3 GeV, photon absolute pseudorapidity |η| < 2.4, diphoton invariant mass greater than 6 GeV, diphoton transverse momentum lower than 2 GeV and diphoton acoplanarity below 0.01, is measured to be 70 ± 24 (stat.) ± 17 (syst.) nb, which is in agreement with the standard model predictions.« less

Wire-grid electromagnetic modelling of metallic cylindrical objects with arbitrary section, for Ground Penetrating Radar applications

NASA Astrophysics Data System (ADS)

Adabi, Saba; Pajewski, Lara

2014-05-01

This work deals with the electromagnetic wire-grid modelling of metallic cylindrical objects, buried in the ground or embedded in a structure, for example in a wall or in a concrete slab. Wire-grid modelling of conducting objects was introduced by Richmond in 1966 [1] and, since then, this method has been extensively used over the years to simulate arbitrarily-shaped objects and compute radiation patterns of antennas, as well as the electromagnetic field scattered by targets. For any wire-grid model, a fundamental question is the choice of the optimum wire radius and grid spacing. The most widely used criterion to fix the wire size is the so-called same-area rule [2], coming from empirical observation: the total surface area of the wires has to be equal to the surface area of the object being modelled. However, just few authors have investigated the validity of this criterion. Ludwig [3] studied the reliability of the rule by examining the canonical radiation problem of a transverse magnetic field by a circular cylinder fed with a uniform surface current, compared with a wire-grid model; he concluded that the same-area rule is optimum and that too thin wires are just as bad as too thick ones. Paknys [4] investigated the accuracy of the same-area rule for the modelling of a circular cylinder with a uniform current on it, continuing the study initiated in [3], or illuminated by a transverse magnetic monochromatic plane wave; he deduced that the same-area rule is optimal and that the field inside the cylinder is most sensitive to the wire radius than the field outside the object, so being a good error indicator. In [5], a circular cylinder was considered, embedded in a dielectric half-space and illuminated by a transverse magnetic monochromatic plane wave; the scattered near field was calculated by using the Cylindrical-Wave Approach and numerical results, obtained for different wire-grid models in the spectral domain, were compared with the exact solution. The Authors demonstrated that the well-known same-area criterion yields affordable results but is quite far from being the optimum: better results can be obtained with a wire radius shorter than what is suggested by the rule. In utility detection, quality controls of reinforced concrete, and other civil-engineering applications, many sought targets are long and thin: in these cases, two-dimensional scattering methods can be employed for the electromagnetic modelling of scenarios. In the present work, the freeware tool GPRMAX2D [6], implementing the Finite-Difference Time-Domain method, is used to implement the wire-grid modelling of buried two-dimensional objects. The source is a line of current, with Ricker waveform. Results obtained in [5] are confirmed in the time domain and for different geometries. The highest accuracy is obtained by shortening the radius of about 10%. It seems that fewer (and larger) wires need minor shortening; however, more detailed investigations are required. We suggest to use at least 8 - 10 wires per wavelength if the field scattered by the structure has to be evaluated. The internal field is much more sensitive to the modelling configuration than the external one, and more wires should be employed when shielding effects are concerned. We plan to conduct a more comprehensive analysis, in order to extract guidelines for wire sizing, to be validated on different shapes. We also look forward to verifying the possibility of using the wire-grid modelling method for the simulation of slotted objects. This work is a contribution to COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar". The Authors thanks COST for funding COST Action TU1208. References [1] J.H. Richmond, A wire grid model for scattering by conducting bodies, IEEE Trans. Antennas Propagation AP-14 (1966), pp. 782-786. [2] S.M. Rao, D.R. Wilton, A.W. Glisson, Electromagnetic scattering by surfaces of arbitrary shape, IEEE Trans. Antennas Propagation AP-30 (1982), pp. 409-418. [3] A.C. Ludwig, Wire grid modeling of surfaces, IEEE Trans. Antennas Propagation AP-35 (1987), pp. 1045-1048. [4] R.J. Paknys, The near field of a wire grid model, IEEE Trans. Antennas Propagation 39 (1991), pp. 994-999. [5] F. Frezza, L. Pajewski, C. Ponti, G. Schettini, Accurate wire-grid modelling of buried conducting cylindrical scatterers, Nondestructive Testing and Evaluation (2012), 27, pp. 199-207. [6] A. Giannopoulos, Modelling ground penetrating radar by GPRMAX. Construction and Building Materials (2005), 19, pp. 755-762.

New Basis Functions for the Electromagnetic Solution of Arbitrarily-shaped, Three Dimensional Conducting Bodies Using Method of Moments

NASA Technical Reports Server (NTRS)

Mackenzie, Anne I.; Baginski, Michael E.; Rao, Sadasiva M.

2007-01-01

In this work, we present a new set of basis functions, de ned over a pair of planar triangular patches, for the solution of electromagnetic scattering and radiation problems associated with arbitrarily-shaped surfaces using the method of moments solution procedure. The basis functions are constant over the function subdomain and resemble pulse functions for one and two dimensional problems. Further, another set of basis functions, point-wise orthogonal to the first set, is also de ned over the same function space. The primary objective of developing these basis functions is to utilize them for the electromagnetic solution involving conducting, dielectric, and composite bodies. However, in the present work, only the conducting body solution is presented and compared with other data.

New Basis Functions for the Electromagnetic Solution of Arbitrarily-shaped, Three Dimensional Conducting Bodies using Method of Moments

NASA Technical Reports Server (NTRS)

Mackenzie, Anne I.; Baginski, Michael E.; Rao, Sadasiva M.

2008-01-01

In this work, we present a new set of basis functions, defined over a pair of planar triangular patches, for the solution of electromagnetic scattering and radiation problems associated with arbitrarily-shaped surfaces using the method of moments solution procedure. The basis functions are constant over the function subdomain and resemble pulse functions for one and two dimensional problems. Further, another set of basis functions, point-wise orthogonal to the first set, is also defined over the same function space. The primary objective of developing these basis functions is to utilize them for the electromagnetic solution involving conducting, dielectric, and composite bodies. However, in the present work, only the conducting body solution is presented and compared with other data.

A self-consistent high- and low-frequency scattering model for cirrus

NASA Astrophysics Data System (ADS)

Baran, Anthony J.; Cotton, Richard; Havemann, Stephan; C.-Labonnote, Laurent; Marenco, Franco

2013-05-01

This paper demonstrates that an ensemble model of cirrus ice crystals that follows observed mass-dimensional power laws can predict the scattering properties of cirrus across the electromagnetic spectrum, without the need for tailor made scattering models for particular regions of the spectrum. The ensemble model predicts a mass-dimensional power law of the following form, mass ∝ D2 (where D is the maximum dimension of the ice crystal). This same mass-dimensional power law is applied across the spectrum to predict the particle size distribution (PSD) using a moment estimation parameterization of the PSD. The PSD parameterization predicts the original PSD, using in-situ estimates (bulk measurements) of the ice water content (IWC) and measurements of the in-cloud temperature; the measurements were obtained from a number of mid-latitude cirrus cases, which occurred over the U.K. during the winter and spring of 2010. It is demonstrated that the ensemble model predicts lidar backscatter estimates, at 0.355 μm, of the volume extinction coefficient and total solar optical depth to within current experimental uncertainties, hyperspectral brightness temperature measurements of the terrestrial region (800 cm-1 - 1200 cm-1) to generally well within ±1 K in the window regions, and the 35 GHz radar reflectivity to within ±2 dBZ. Therefore, for simulation of satellite radiances within general circulation models, and retrieval of cirrus properties, scattering models, which are demonstrated to be physically consistent across the electromagnetic spectrum, should be preferred.

Stationary and non-stationary nonlinear optical spectroscopy on surface polaritons

NASA Technical Reports Server (NTRS)

Ponath, H. E.

1984-01-01

A phenomenological theory is given for non-stationary electromagnetic surface waves propagating along the boundary plane between two homogeneous isotropic media. The description of nonlinear optical effects using shortened wave equations is demonstrated for spontaneous and simulated Raman scattering processes on surface polaritons.