Rapid decay of nonlinear whistler waves in two dimensions: Full particle simulation

NASA Astrophysics Data System (ADS)

Umeda, Takayuki; Saito, Shinji; Nariyuki, Yasuhiro

2017-05-01

The decay of a nonlinear, short-wavelength, and monochromatic electromagnetic whistler wave is investigated by utilizing a two-dimensional (2D) fully relativistic electromagnetic particle-in-cell code. The simulation is performed under a low-beta condition in which the plasma pressure is much lower than the magnetic pressure. It has been shown that the nonlinear (large-amplitude) parent whistler wave decays through the parametric instability in a one-dimensional (1D) system. The present study shows that there is another channel for the decay of the parent whistler wave in 2D, which is much faster than in the timescale of the parametric decay in 1D. The parent whistler wave decays into two sideband daughter whistlers propagating obliquely with respect to the ambient magnetic field with a frequency close to the parent wave and two quasi-perpendicular electromagnetic modes with a frequency close to zero via a 2D decay instability. The two sideband daughter oblique whistlers also enhance a nonlinear longitudinal electrostatic wave via a three-wave interaction as a secondary process.

Novel methodology to characterize electromagnetic exposure of the brain

NASA Astrophysics Data System (ADS)

Crespo-Valero, Pedro; Christopoulou, Maria; Zefferer, Marcel; Christ, Andreas; Achermann, Peter; Nikita, Konstantina S.; Kuster, Niels

2011-01-01

Due to the greatly non-uniform field distribution induced in brain tissues by radio frequency electromagnetic sources, the exposure of anatomical and functional regions of the brain may be a key issue in interpreting laboratory findings and epidemiological studies concerning endpoints related to the central nervous system. This paper introduces the Talairach atlas in characterization of the electromagnetic exposure of the brain. A hierarchical labeling scheme is mapped onto high-resolution human models. This procedure is fully automatic and allows identification of over a thousand different sites all over the brain. The electromagnetic absorption can then be extracted and interpreted in every region or combination of regions in the brain, depending on the characterization goals. The application examples show how this methodology enhances the dosimetry assessment of the brain based on results obtained by either finite difference time domain simulations or measurements delivered by test compliance dosimetry systems. Applications include, among others, the detailed dosimetric analysis of the exposure of the brain during cell phone use, improved design of exposure setups for human studies or medical diagnostic and therapeutic devices using electromagnetic fields or ultrasound.

Rapid Charged Geosynchronous Debris Perturbation Modeling of Electrodynamic Disturbances

NASA Astrophysics Data System (ADS)

Hughes, Joseph; Schaub, Hanspeter

2018-06-01

Charged space objects experience small perturbative torques and forces from their interaction with Earth's magnetic field. These small perturbations can change the orbits of lightweight, uncontrolled debris objects dramatically even over short periods. This paper investigates the effects of the isolated Lorentz force, the effects of including or neglecting this and other electromagnetic perturbations in a full propagation, and then analyzes for which objects electromagnetic effects have the most impact. It is found that electromagnetic forces have a negligible impact on their own. However, if the center of charge is not collocated with the center of mass, electromagnetic torques are produced which do impact the attitude, and thus the position by affecting the direction and magnitude of the solar radiation pressure force. The objects for which electrostatic torques have the most influence are charged above the kilovolt level, have a difference between their center of mass and center of charge, have highly attitude-dependent cross-sectional area, and are not spinning stably about an axis of maximum inertia. Fully coupled numerical simulation illustrate the impact of electromagnetic disturbances through the solar radiation pressure coupling.

Rapid Charged Geosynchronous Debris Perturbation Modeling of Electrodynamic Disturbances

NASA Astrophysics Data System (ADS)

Hughes, Joseph; Schaub, Hanspeter

2018-04-01

Charged space objects experience small perturbative torques and forces from their interaction with Earth's magnetic field. These small perturbations can change the orbits of lightweight, uncontrolled debris objects dramatically even over short periods. This paper investigates the effects of the isolated Lorentz force, the effects of including or neglecting this and other electromagnetic perturbations in a full propagation, and then analyzes for which objects electromagnetic effects have the most impact. It is found that electromagnetic forces have a negligible impact on their own. However, if the center of charge is not collocated with the center of mass, electromagnetic torques are produced which do impact the attitude, and thus the position by affecting the direction and magnitude of the solar radiation pressure force. The objects for which electrostatic torques have the most influence are charged above the kilovolt level, have a difference between their center of mass and center of charge, have highly attitude-dependent cross-sectional area, and are not spinning stably about an axis of maximum inertia. Fully coupled numerical simulation illustrate the impact of electromagnetic disturbances through the solar radiation pressure coupling.

The distinguishing signature of magnetic Penrose process

NASA Astrophysics Data System (ADS)

Dadhich, Naresh; Tursunov, Arman; Ahmedov, Bobomurat; Stuchlík, Zdeněk

2018-07-01

In this Letter, we wish to point out that the distinguishing feature of magnetic Penrose process (MPP) is its super high-efficiency exceeding 100 per cent (which was established in mid 1980s for discrete particle accretion) of extraction of rotational energy of a rotating black hole electromagnetically for a magnetic field of milli Gauss order. Another similar process, which is also driven by the electromagnetic field, is Blandford-Znajek mechanism (BZ) that could be envisaged as high magnetic field limit MPP as it requires threshold magnetic field of order 104 G. Recent simulation studies of fully relativistic magnetohydrodynamic (MHD) flows have borne out super high-efficiency signature of the process for high magnetic field regime; viz BZ. We would like to make a clear prediction that similar simulation studies of MHD flows for low magnetic field regime, where BZ would be inoperative, would also have superefficiency.

Investigation of Fully Three-Dimensional Helical RF Field Effects on TWT Beam/Circuit Interaction

NASA Technical Reports Server (NTRS)

Kory, Carol L.

2000-01-01

A fully three-dimensional (3D), time-dependent, helical traveling wave-tube (TWT) interaction model has been developed using the electromagnetic particle-in-cell (PIC) code MAFIA. The model includes a short section of helical slow-wave circuit with excitation fed by RF input/output couplers, and electron beam contained by periodic permanent magnet (PPM) focusing. All components of the model are simulated in three dimensions allowing the effects of the fully 3D helical fields on RF circuit/beam interaction to be investigated for the first time. The development of the interaction model is presented, and predicted TWT performance using 2.5D and 3D models is compared to investigate the effect of conventional approximations used in TWT analyses.

A curvilinear, fully implicit, conservative electromagnetic PIC algorithm in multiple dimensions

DOE PAGES

Chacon, L.; Chen, G.

2016-04-19

Here, we extend a recently proposed fully implicit PIC algorithm for the Vlasov–Darwin model in multiple dimensions (Chen and Chacón (2015) [1]) to curvilinear geometry. As in the Cartesian case, the approach is based on a potential formulation (Φ, A), and overcomes many difficulties of traditional semi-implicit Darwin PIC algorithms. Conservation theorems for local charge and global energy are derived in curvilinear representation, and then enforced discretely by a careful choice of the discretization of field and particle equations. Additionally, the algorithm conserves canonical-momentum in any ignorable direction, and preserves the Coulomb gauge ∇ • A = 0 exactly. Anmore » asymptotically well-posed fluid preconditioner allows efficient use of large cell sizes, which are determined by accuracy considerations, not stability, and can be orders of magnitude larger than required in a standard explicit electromagnetic PIC simulation. We demonstrate the accuracy and efficiency properties of the algorithm with numerical experiments in mapped meshes in 1D-3V and 2D-3V.« less

A curvilinear, fully implicit, conservative electromagnetic PIC algorithm in multiple dimensions

NASA Astrophysics Data System (ADS)

Chacón, L.; Chen, G.

2016-07-01

We extend a recently proposed fully implicit PIC algorithm for the Vlasov-Darwin model in multiple dimensions (Chen and Chacón (2015) [1]) to curvilinear geometry. As in the Cartesian case, the approach is based on a potential formulation (ϕ, A), and overcomes many difficulties of traditional semi-implicit Darwin PIC algorithms. Conservation theorems for local charge and global energy are derived in curvilinear representation, and then enforced discretely by a careful choice of the discretization of field and particle equations. Additionally, the algorithm conserves canonical-momentum in any ignorable direction, and preserves the Coulomb gauge ∇ ṡ A = 0 exactly. An asymptotically well-posed fluid preconditioner allows efficient use of large cell sizes, which are determined by accuracy considerations, not stability, and can be orders of magnitude larger than required in a standard explicit electromagnetic PIC simulation. We demonstrate the accuracy and efficiency properties of the algorithm with numerical experiments in mapped meshes in 1D-3V and 2D-3V.

A curvilinear, fully implicit, conservative electromagnetic PIC algorithm in multiple dimensions

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

Chacon, L.; Chen, G.

Here, we extend a recently proposed fully implicit PIC algorithm for the Vlasov–Darwin model in multiple dimensions (Chen and Chacón (2015) [1]) to curvilinear geometry. As in the Cartesian case, the approach is based on a potential formulation (Φ, A), and overcomes many difficulties of traditional semi-implicit Darwin PIC algorithms. Conservation theorems for local charge and global energy are derived in curvilinear representation, and then enforced discretely by a careful choice of the discretization of field and particle equations. Additionally, the algorithm conserves canonical-momentum in any ignorable direction, and preserves the Coulomb gauge ∇ • A = 0 exactly. Anmore » asymptotically well-posed fluid preconditioner allows efficient use of large cell sizes, which are determined by accuracy considerations, not stability, and can be orders of magnitude larger than required in a standard explicit electromagnetic PIC simulation. We demonstrate the accuracy and efficiency properties of the algorithm with numerical experiments in mapped meshes in 1D-3V and 2D-3V.« less

Detailed electromagnetic simulation for the structural color of butterfly wings.

PubMed

Lee, R Todd; Smith, Glenn S

2009-07-20

Many species of butterflies exhibit interesting optical phenomena due to structural color. The physical reason for this color is subwavelength features on the surface of a single scale. The exposed surface of a scale is covered with a ridge structure. The fully three-dimensional, periodic, finite-difference time-domain method is used to create a detailed electromagnetic model of a generic ridge. A novel method for presenting the three-dimensional observed color pattern is developed. Using these tools, the change in color that is a result of varying individual features of the scale is explored. Computational models are developed that are similar to three butterflies: Morpho rhetenor, Troides magellanus, and Ancyluris meliboeus.

Optical control of light propagation in photonic crystal based on electromagnetically induced transparency

NASA Astrophysics Data System (ADS)

Dan, Wang; Jin-Ze, Wu; Jun-Xiang, Zhang

2016-06-01

A kind of photonic crystal structure with modulation of the refractive index is investigated both experimentally and theoretically for exploiting electromagnetically induced transparency (EIT). The combination of EIT with periodically modulated refractive index medium gives rise to high efficiency reflection as well as forbidden transmission in a three-level atomic system coupled by standing wave. We show an accurate theoretical simulation via transfer-matrix theory, automatically accounting for multilayer reflections, thus fully demonstrate the existence of photonic crystal structure in atomic vapor. Project supported by the National Natural Science Foundation of China (Grant No. 11574188) and the Project for Excellent Research Team of the National Natural Science Foundation of China (Grant No. 61121064).

Two-Dimensional Signal Processing and Storage and Theory and Applications of Electromagnetic Measurements.

DTIC Science & Technology

1983-06-01

system, provides a convenient, low- noise , fully parallel method of improving contrast and enhancing structural detail in an image prior to input to a...directed towards problems in deconvolution, reconstruction from projections, bandlimited extrapolation, and shift varying deblurring of images...deconvolution algorithm has been studied with promising 5 results [I] for simulated motion blurs. Future work will focus on noise effects and the extension

A multi-dimensional nonlinearly implicit, electromagnetic Vlasov-Darwin particle-in-cell (PIC) algorithm

NASA Astrophysics Data System (ADS)

Chen, Guangye; Chacón, Luis; CoCoMans Team

2014-10-01

For decades, the Vlasov-Darwin model has been recognized to be attractive for PIC simulations (to avoid radiative noise issues) in non-radiative electromagnetic regimes. However, the Darwin model results in elliptic field equations that renders explicit time integration unconditionally unstable. Improving on linearly implicit schemes, fully implicit PIC algorithms for both electrostatic and electromagnetic regimes, with exact discrete energy and charge conservation properties, have been recently developed in 1D. This study builds on these recent algorithms to develop an implicit, orbit-averaged, time-space-centered finite difference scheme for the particle-field equations in multiple dimensions. The algorithm conserves energy, charge, and canonical-momentum exactly, even with grid packing. A simple fluid preconditioner allows efficient use of large timesteps, O (√{mi/me}c/veT) larger than the explicit CFL. We demonstrate the accuracy and efficiency properties of the of the algorithm with various numerical experiments in 2D3V.

Numerical simulation of electromagnetic wave attenuation in a nonequilibrium chemically reacting hypervelocity flow

NASA Astrophysics Data System (ADS)

Nusca, Michael Joseph, Jr.

The effects of various gasdynamic phenomena on the attenuation of an electromagnetic wave propagating through the nonequilibrium chemically reacting air flow field generated by an aerodynamic body travelling at high velocity is investigated. The nonequilibrium flow field is assumed to consist of seven species including nitric oxide ions and free electrons. The ionization of oxygen and nitrogen atoms is ignored. The aerodynamic body considered is a blunt wedge. The nonequilibrium chemically reacting flow field around this body is numerically simulated using a computer code based on computational fluid dynamics. The computer code solves the Navier-Stokes equations including mass diffusion and heat transfer, using a time-marching, explicit Runge-Kutta scheme. A nonequilibrium air kinetics model consisting of seven species and twenty-eight reactions as well as an equilibrium air model consisting of the same seven species are used. The body surface boundaries are considered as adiabatic or isothermal walls, as well as fully-catalytic and non-catalytic surfaces. Both laminar and turbulent flows are considered; wall generated flow turbulence is simulated using an algebraic mixing length model. An electromagnetic wave is considered as originating from an antenna within the body and is effected by the free electrons in the chemically reacting flow. Analysis of the electromagnetics is performed separately from the fluid dynamic analysis using a series solution of Maxwell's equations valid for the propagation of a long-wavelength plane electromagnetic wave through a thin (i.e., in comparison to wavelength) inhomogeneous plasma layer. The plasma layer is the chemically reacting shock layer around the body. The Navier-Stokes equations are uncoupled from Maxwell's equations. The results of this computational study demonstrate for the first time and in a systematic fashion, the importance of several parameters including equilibrium chemistry, nonequilibrium chemical kinetics, the reaction mechanism, flow viscosity, mass diffusion, and wall boundary conditions on modeling wave attenuation resulting from the interaction of an electromagnetic wave with an aerodynamic plasma. Comparison is made with experimental data.

A multi-dimensional, energy- and charge-conserving, nonlinearly implicit, electromagnetic Vlasov–Darwin particle-in-cell algorithm

DOE PAGES

Chen, G.; Chacón, L.

2015-08-11

For decades, the Vlasov–Darwin model has been recognized to be attractive for particle-in-cell (PIC) kinetic plasma simulations in non-radiative electromagnetic regimes, to avoid radiative noise issues and gain computational efficiency. However, the Darwin model results in an elliptic set of field equations that renders conventional explicit time integration unconditionally unstable. We explore a fully implicit PIC algorithm for the Vlasov–Darwin model in multiple dimensions, which overcomes many difficulties of traditional semi-implicit Darwin PIC algorithms. The finite-difference scheme for Darwin field equations and particle equations of motion is space–time-centered, employing particle sub-cycling and orbit-averaging. This algorithm conserves total energy, local charge,more » canonical-momentum in the ignorable direction, and preserves the Coulomb gauge exactly. An asymptotically well-posed fluid preconditioner allows efficient use of large cell sizes, which are determined by accuracy considerations, not stability, and can be orders of magnitude larger than required in a standard explicit electromagnetic PIC simulation. Finally, we demonstrate the accuracy and efficiency properties of the algorithm with various numerical experiments in 2D–3V.« less

On Electromagnetic Modulation of Flow Instabilities, Mixing and Heat Transfer in Conducting and Magnetized Fluids

NASA Astrophysics Data System (ADS)

Kenjeres, S.

2016-09-01

In the present paper we give a concise review of some recent highlights of our research dealing with electromagnetic control of flow, mixing and heat transfer of electrically conductive or magnetized fluids. We apply a combination of state-of-art numerical (DNS and LES) and experimental (PIV and LIF) techniques to provide fundamental insights into the complex phenomena of interactions between imposed (or induced) electromagnetic fields and underlying fluid flow. Our analysis covers an extensive range of working fluids, i.e. weakly- and highly-electrically-conductive, as well as magnetized fluids. These interactions are defined through the presence of different types of body forces acting per volume of fluid. A fully closed system of governing equations containing an extended set of the Navier-Stokes and a simplified set of the Maxwell equations is presented. The four characteristic examples are selected: the electromagnetic control of self-sustained jet oscillations, the electromagnetic enhancement of heat transfer in thermal convection, the wake interactions behind magnetic obstacles and finally, the thermo-magnetic convection in differentially heated cubical enclosure. The comparative assessment between experimental and numerical results is presented. It is concluded that generally good agreement between simulations and experiments is obtained for all cases considered, proving the concept of electromagnetic modulation, which can be used in numerous technological applications.

Instabilities and Turbulence Generation by Pick-Up Ion Distributions in the Outer Heliosheath

NASA Astrophysics Data System (ADS)

Weichman, K.; Roytershteyn, V.; Delzanno, G. L.; Pogorelov, N.

2017-12-01

Pick-up ions (PUIs) play a significant role in the dynamics of the heliosphere. One problem that has attracted significant attention is the stability of ring-like distributions of PUIs and the electromagnetic fluctuations that could be generated by PUI distributions. For example, PUI stability is relevant to theories attempting to identify the origins of the IBEX ribbon. PUIs have previously been investigated by linear stability analysis of model (e.g. Gaussian) rings and corresponding computer simulations. The majority of these simulations utilized particle-in-cell methods which suffer from accuracy limitations imposed by the statistical noise associated with representing the plasma by a relatively small number of computational particles. In this work, we utilize highly accurate spectral Vlasov simulations conducted using the fully kinetic implicit code SPS (Spectral Plasma Solver) to investigate the PUI distributions inferred from a global heliospheric model (Heerikhuisen et al., 2016). Results are compared with those obtained by hybrid and fully kinetic particle-in-cell methods.

The interaction with the lower ionosphere of electromagnetic pulses from lightning: Excitation of optical emissions

NASA Technical Reports Server (NTRS)

Taranenko, Y. N.; Inan, U. S.; Bell, T. F.

1993-01-01

A self consistent and fully kinetic simulation of the interaction of lightning radiated electromagnetic (EM) pulses with the nighttime lower ionosphere indicates that optical emissions observable with conventional instruments would be excited. For example, emissions of the 1st and 2nd positive bands of N2 occur at rates reaching 7 x 10(exp 7) and 10(exp 7) cu cm/s respectively at 92 km altitude for a lightning discharge with an electric field E(sub 100) = 20 V/m (normalized to a 100 km distance). The maximum height integrated intensities of these emissions are 4 x 10(exp 7) and 6 x 10(exp 6) R respectively, lasting for approx. 50 micrometers.

The effect of a longitudinal density gradient on electron plasma wake field acceleration

NASA Astrophysics Data System (ADS)

Tsiklauri, David

2016-12-01

Three-dimensional, particle-in-cell, fully electromagnetic simulations of electron plasma wake field acceleration in the blow-out regime are presented. Earlier results are extended by (i) studying the effect of a longitudinal density gradient, (ii) avoiding the use of a co-moving simulation box, (iii) inclusion of ion motion, and (iv) studying fully electromagnetic plasma wake fields. It is established that injecting driving and trailing electron bunches into a positive density gradient of 10-fold increasing density over 10 cm long lithium vapour plasma results in spatially more compact and three times larger, compared with the uniform density case, electric fields (-6.4×1010 V m-1), leading to acceleration of the trailing bunch up to 24.4 GeV (starting from an initial 20.4 GeV), with energy transfer efficiencies from the leading to trailing bunch of 75%. In the uniform density case, a -2.5×1010 V m-1 wake is created leading to acceleration of the trailing bunch up to 22.4 GeV, with energy transfer efficiencies of 65%. It is also established that injecting the electron bunches into a negative density gradient of 10-fold decreasing density over 10 cm long plasma results in spatially more spread and two and a half smaller electric fields (-1.0×1010 V m-1), leading to a weaker acceleration of the trailing bunch up to 21.4 GeV, with energy transfer efficiencies of 45%. Taking ion motions into consideration shows that in the plasma wake ion number density can increase over a few times the background value. It is also shown that transverse electromagnetic fields in a plasma wake are of the same order as the longitudinal (electrostatic) ones.

On the interplay of gas dynamics and the electromagnetic field in an atmospheric Ar/H2 microwave plasma torch

NASA Astrophysics Data System (ADS)

Synek, Petr; Obrusník, Adam; Hübner, Simon; Nijdam, Sander; Zajíčková, Lenka

2015-04-01

A complementary simulation and experimental study of an atmospheric pressure microwave torch operating in pure argon or argon/hydrogen mixtures is presented. The modelling part describes a numerical model coupling the gas dynamics and mixing to the electromagnetic field simulations. Since the numerical model is not fully self-consistent and requires the electron density as an input, quite extensive spatially resolved Stark broadening measurements were performed for various gas compositions and input powers. In addition, the experimental part includes Rayleigh scattering measurements, which are used for the validation of the model. The paper comments on the changes in the gas temperature and hydrogen dissociation with the gas composition and input power, showing in particular that the dependence on the gas composition is relatively strong and non-monotonic. In addition, the work provides interesting insight into the plasma sustainment mechanism by showing that the power absorption profile in the plasma has two distinct maxima: one at the nozzle tip and one further upstream.

On electromagnetic forming processes in finitely strained solids: Theory and examples

NASA Astrophysics Data System (ADS)

Thomas, J. D.; Triantafyllidis, N.

2009-08-01

The process of electromagnetic forming (EMF) is a high velocity manufacturing technique that uses electromagnetic (Lorentz) body forces to shape sheet metal parts. EMF holds several advantages over conventional forming techniques: speed, repeatability, one-sided tooling, and most importantly considerable ductility increase in several metals. Current modeling techniques for EMF processes are not based on coupled variational principles to simultaneously account for electromagnetic and mechanical effects. Typically, separate solutions to the electromagnetic (Maxwell) and motion (Newton) equations are combined in staggered or lock-step methods, sequentially solving the mechanical and electromagnetic problems. The present work addresses these issues by introducing a fully coupled Lagrangian (reference configuration) least-action variational principle, involving magnetic flux and electric potentials and the displacement field as independent variables. The corresponding Euler-Lagrange equations are Maxwell's and Newton's equations in the reference configuration, which are shown to coincide with their current configuration counterparts obtained independently by a direct approach. The general theory is subsequently simplified for EMF processes by considering the eddy current approximation. Next, an application is presented for axisymmetric EMF problems. It is shown that the proposed variational principle forms the basis of a variational integration numerical scheme that provides an efficient staggered solution algorithm. As an illustration a number of such processes are simulated, inspired by recent experiments of freely expanding uncoated and polyurea-coated aluminum tubes.

Dicke-model simulation via cavity-assisted Raman transitions

NASA Astrophysics Data System (ADS)

Zhang, Zhiqiang; Lee, Chern Hui; Kumar, Ravi; Arnold, K. J.; Masson, Stuart J.; Grimsmo, A. L.; Parkins, A. S.; Barrett, M. D.

2018-04-01

The Dicke model is of fundamental importance in quantum mechanics for understanding the collective behavior of atoms coupled to a single electromagnetic mode. Here, we demonstrate a Dicke-model simulation via cavity-assisted Raman transitions in a configuration using counterpropagating laser beams. The observations indicate that motional effects should be included to fully account for the results. These results are contrary to experiments using single-beam and copropagating configurations. We give a theoretical description that accounts for the beam geometries used in the experiments and indicates the potential role of motional effects. In particular, a model is given that highlights the influence of Doppler broadening on the observed phase-transition thresholds.

A fully coupled flow simulation around spacecraft in low earth orbit

NASA Technical Reports Server (NTRS)

Justiz, C. R.; Sega, R. M.

1991-01-01

The primary objective of this investigation is to provide a full flow simulation of a spacecraft in low earth orbit (LEO). Due to the nature of the environment, the simulation includes the highly coupled effects of neutral particle flow, free stream plasma flow, nonequilibrium gas dynamics effects, spacecraft charging and electromagnetic field effects. Emphasis is placed on the near wake phenomenon and will be verified in space by the Wake Shield Facility (WSF) and developed for application to Space Station conditions as well as for other spacecraft. The WSF is a metallic disk-type structure that will provide a controlled space platform for highly accurate measurements. Preliminary results are presented for a full flow around a metallic disk.

SLC injector modeling

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

Hanerfeld, H; Herrmannsfeldt, W.B.; James, M.B.

1985-03-01

The injector for the Stanford Linear Collider is being studied using the fully electromagnetic particle-in-cell program MASK. The program takes account of cylindrically symmetrical rf fields from the external source, as well as fields produced by the beam and dc magnetic fields. It calculates the radial and longitudinal motion of electrons and plots their positions in various planes in phase space. Bunching parameters can be optimized and insights into the bunching process and emittance growth have been gained. The results of the simulations are compared to the experimental results.

Attenuation characteristics of electromagnetic waves in a weak collisional and fully ionized dusty plasma

NASA Astrophysics Data System (ADS)

Dan, Li; Guo, Li-Xin; Li, Jiang-Ting; Chen, Wei; Yan, Xu; Huang, Qing-Qing

2017-09-01

The expression of complex dielectric permittivity for non-magnetized fully ionized dusty plasma is obtained based on the kinetic equation in the Fokker-Planck-Landau collision model and the charging equation of the statistical theory. The influences of density, average size of dust grains, and balanced charging of the charge number of dust particles on the attenuation properties of electromagnetic waves in fully ionized dusty plasma are investigated by calculating the attenuation constant. In addition, the attenuation characteristics of weakly ionized and fully ionized dusty plasmas are compared. Results enriched the physical mechanisms of microwave attenuation for fully ionized dusty plasma and provide a theoretical basis for future studies.

UNIPIC code for simulations of high power microwave devices

NASA Astrophysics Data System (ADS)

Wang, Jianguo; Zhang, Dianhui; Liu, Chunliang; Li, Yongdong; Wang, Yue; Wang, Hongguang; Qiao, Hailiang; Li, Xiaoze

2009-03-01

In this paper, UNIPIC code, a new member in the family of fully electromagnetic particle-in-cell (PIC) codes for simulations of high power microwave (HPM) generation, is introduced. In the UNIPIC code, the electromagnetic fields are updated using the second-order, finite-difference time-domain (FDTD) method, and the particles are moved using the relativistic Newton-Lorentz force equation. The convolutional perfectly matched layer method is used to truncate the open boundaries of HPM devices. To model curved surfaces and avoid the time step reduction in the conformal-path FDTD method, CP weakly conditional-stable FDTD (WCS FDTD) method which combines the WCS FDTD and CP-FDTD methods, is implemented. UNIPIC is two-and-a-half dimensional, is written in the object-oriented C++ language, and can be run on a variety of platforms including WINDOWS, LINUX, and UNIX. Users can use the graphical user's interface to create the geometric structures of the simulated HPM devices, or input the old structures created before. Numerical experiments on some typical HPM devices by using the UNIPIC code are given. The results are compared to those obtained from some well-known PIC codes, which agree well with each other.

Proceedings of the 14th International Conference on the Numerical Simulation of Plasmas

NASA Astrophysics Data System (ADS)

Partial Contents are as follows: Numerical Simulations of the Vlasov-Maxwell Equations by Coupled Particle-Finite Element Methods on Unstructured Meshes; Electromagnetic PIC Simulations Using Finite Elements on Unstructured Grids; Modelling Travelling Wave Output Structures with the Particle-in-Cell Code CONDOR; SST--A Single-Slice Particle Simulation Code; Graphical Display and Animation of Data Produced by Electromagnetic, Particle-in-Cell Codes; A Post-Processor for the PEST Code; Gray Scale Rendering of Beam Profile Data; A 2D Electromagnetic PIC Code for Distributed Memory Parallel Computers; 3-D Electromagnetic PIC Simulation on the NRL Connection Machine; Plasma PIC Simulations on MIMD Computers; Vlasov-Maxwell Algorithm for Electromagnetic Plasma Simulation on Distributed Architectures; MHD Boundary Layer Calculation Using the Vortex Method; and Eulerian Codes for Plasma Simulations.

Waveguiding and bending modes in a plasma photonic crystal bandgap device

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

Wang, B., E-mail: bwang17@stanford.edu; Cappelli, M. A.

2016-06-15

Waveguiding and bending modes are investigated in a fully tunable plasma photonic crystal. The plasma device actively controls the propagation of free space electromagnetic waves in the S to X band of the microwave spectrum. An array of discharge plasma tubes form a square crystal lattice exhibiting a well-defined bandgap, with individual active switching of the plasma elements to allow for waveguiding and bending modes to be generated dynamically. We show, through simulations and experiments, the existence of transverse electric (TE) mode waveguiding and bending modes.

Simulating plasma production from hypervelocity impacts

NASA Astrophysics Data System (ADS)

Fletcher, Alex; Close, Sigrid; Mathias, Donovan

2015-09-01

Hypervelocity particles, such as meteoroids and space debris, routinely impact spacecraft and are energetic enough to vaporize and ionize themselves and as well as a portion of the target material. The resulting plasma rapidly expands into the surrounding vacuum. While plasma measurements from hypervelocity impacts have been made using ground-based technologies such as light gas guns and Van de Graaff dust accelerators, some of the basic plasma properties vary significantly between experiments. There have been both ground-based and in-situ measurements of radio frequency (RF) emission from hypervelocity impacts, but the physical mechanism responsible and the possible connection to the impact-produced plasma are not well understood. Under certain conditions, the impact-produced plasma can have deleterious effects on spacecraft electronics by providing a new current path, triggering an electrostatic discharge, causing electromagnetic interference, or generating an electromagnetic pulse. Multi-physics simulations of plasma production from hypervelocity impacts are presented. These simulations incorporate elasticity and plasticity of the solid target, phase change and plasma formation, and non-ideal plasma physics due to the high density and low temperature of the plasma. A smoothed particle hydrodynamics method is used to perform a continuum dynamics simulation with these additional physics. By examining a series of hypervelocity impacts, basic properties of the impact produced plasma plume (density, temperature, expansion speed, charge state) are determined for impactor speeds between 10 and 72 km/s. For a large range of higher impact speeds (30-72 km/s), we find the temperature is unvarying at 2.5 eV. We also find that the plasma plume is weakly ionized for impact speeds less than 14 km/s and fully ionized for impact speeds greater than 20 km/s, independent of impactor mass. This is the same velocity threshold for the detection of RF emission in recent Van de Graaff experiments, suggesting that the RF is correlated to the formation of fully ionized plasma.

Simulating plasma production from hypervelocity impacts

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

Fletcher, Alex, E-mail: alexcf@stanford.edu; Close, Sigrid; Mathias, Donovan

2015-09-15

Hypervelocity particles, such as meteoroids and space debris, routinely impact spacecraft and are energetic enough to vaporize and ionize themselves and as well as a portion of the target material. The resulting plasma rapidly expands into the surrounding vacuum. While plasma measurements from hypervelocity impacts have been made using ground-based technologies such as light gas guns and Van de Graaff dust accelerators, some of the basic plasma properties vary significantly between experiments. There have been both ground-based and in-situ measurements of radio frequency (RF) emission from hypervelocity impacts, but the physical mechanism responsible and the possible connection to the impact-producedmore » plasma are not well understood. Under certain conditions, the impact-produced plasma can have deleterious effects on spacecraft electronics by providing a new current path, triggering an electrostatic discharge, causing electromagnetic interference, or generating an electromagnetic pulse. Multi-physics simulations of plasma production from hypervelocity impacts are presented. These simulations incorporate elasticity and plasticity of the solid target, phase change and plasma formation, and non-ideal plasma physics due to the high density and low temperature of the plasma. A smoothed particle hydrodynamics method is used to perform a continuum dynamics simulation with these additional physics. By examining a series of hypervelocity impacts, basic properties of the impact produced plasma plume (density, temperature, expansion speed, charge state) are determined for impactor speeds between 10 and 72 km/s. For a large range of higher impact speeds (30–72 km/s), we find the temperature is unvarying at 2.5 eV. We also find that the plasma plume is weakly ionized for impact speeds less than 14 km/s and fully ionized for impact speeds greater than 20 km/s, independent of impactor mass. This is the same velocity threshold for the detection of RF emission in recent Van de Graaff experiments, suggesting that the RF is correlated to the formation of fully ionized plasma.« less

Intermittency, coherent structures and dissipation in plasma turbulence

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

Wan, M.; Matthaeus, W. H.; Parashar, T. N.

Collisionless dissipation in turbulent plasmas such as the solar wind and the solar corona has been an intensively studied subject recently, with new insights often emerging from numerical simulation. Here we report results from high resolution, fully kinetic simulations of plasma turbulence in both two (2D) and three (3D) dimensions, studying the relationship between intermittency and dissipation. The simulations show development of turbulent coherent structures, characterized by sheet-like current density structures spanning a range of scales. An approximate dissipation measure is employed, based on work done by the electromagnetic field in the local electron fluid frame. This surrogate dissipation measuremore » is highly concentrated in small subvolumes in both 2D and 3D simulations. Fully kinetic simulations are also compared with magnetohydrodynamics (MHD) simulations in terms of coherent structures and dissipation. The interesting result emerges that the conditional averages of dissipation measure scale very similarly with normalized current density J in 2D and 3D particle-in-cell and in MHD. To the extent that the surrogate dissipation measure is accurate, this result implies that on average dissipation scales as ∼J{sup 2} in turbulent kinetic plasma. Multifractal intermittency is seen in the inertial range in both 2D and 3D, but at scales ∼ion inertial length, the scaling is closer to monofractal.« less

Validation of the Electromagnetic Code FACETS for Numerical Simulation of Radar Target Images

DTIC Science & Technology

2009-12-01

Validation of the electromagnetic code FACETS for numerical simulation of radar target images S. Wong...Validation of the electromagnetic code FACETS for numerical simulation of radar target images S. Wong DRDC Ottawa...for simulating radar images of a target is obtained, through direct simulation-to-measurement comparisons. A 3-dimensional computer-aided design

Kinetic simulations of gas breakdown in the dense plasma focus

NASA Astrophysics Data System (ADS)

Bennett, N.; Blasco, M.; Breeding, K.; DiPuccio, V.; Gall, B.; Garcia, M.; Gardner, S.; Gatling, J.; Hagen, E. C.; Luttman, A.; Meehan, B. T.; Molnar, S.; O'Brien, R.; Ormond, E.; Robbins, L.; Savage, M.; Sipe, N.; Welch, D. R.

2017-06-01

The first fully kinetic, collisional, and electromagnetic simulations of the breakdown phase of a MA-scale dense plasma focus are described and shown to agree with measured electrical characteristics, including breakdown time. In the model, avalanche ionization is driven by cathode electron emission, and this results in incomplete gas breakdown along the insulator. This reinforces the importance of the conditioning process that creates a metallic layer on the insulator surface. The simulations, nonetheless, help explain the relationship between the gas pressure, the insulator length, and the coaxial gap width. Previously, researchers noted three breakdown patterns related to pressure. Simulation and analytical results show that at low pressures, long ionization path lengths lead to volumetric breakdown, while high pressures lead to breakdown across the relatively small coaxial electrode gap. In an intermediate pressure regime, ionization path lengths are comparable to the insulator length which promotes ideal breakdown along the insulator surface.

Global two-fluid turbulence simulations of L-H transitions and edge localized mode dynamics in the COMPASS-D tokamak

NASA Astrophysics Data System (ADS)

Thyagaraja, A.; Valovič, M.; Knight, P. J.

2010-04-01

It is shown that the transition from L-mode to H-mode regimes in tokamaks can be reproduced using a two-fluid, fully electromagnetic, plasma model when a suitable particle sink is added at the edge. Such a model is implemented in the CUTIE code [A. Thyagaraja et al., Eur. J. Mech. B/Fluids 23, 475 (2004)] and is illustrated on plasma parameters that mimic those in the COMPASS-D tokamak with electron cyclotron resonance heating [Fielding et al., Plasma Phys. Contr. Fusion 42, A191 (2000)]. In particular, it is shown that holding the heating power, current, and magnetic field constant and increasing the fuelling rate to raise the plasma density leads spontaneously to the formation of an edge transport barrier (ETB) which occurs going from low to higher density experimentally. In the following quiescent period in which the stored energy of the plasma rises linearly with time, a dynamical transition occurs in the simulation with the appearance of features resembling strong edge localized modes. The simulation qualitatively reproduces many features observed in the experiment. Its relative robustness suggests that some, at least of the observed characteristics of ETBs and L-H transitions, can be captured in the global electromagnetic turbulence model.

Tunable electromagnetically induced transparency in integrated silicon photonics circuit.

PubMed

Li, Ang; Bogaerts, Wim

2017-12-11

We comprehensively simulate and experimentally demonstrate a novel approach to generate tunable electromagnetically induced transparency (EIT) in a fully integrated silicon photonics circuit. It can also generate tunable fast and slow light. The circuit is a single ring resonator with two integrated tunable reflectors inside, which form an embedded Fabry-Perot (FP) cavity inside the ring cavity. The mode of the FP cavity can be controlled by tuning the reflections using integrated thermo-optic tuners. Under correct tuning conditions, the interaction of the FP mode and the ring resonance mode will generate a Fano resonance and an EIT response. The extinction ratio and bandwidth of the EIT can be tuned by controlling the reflectors. Measured group delay proves that both fast light and slow light can be generated under different tuning conditions. A maximum group delay of 1100 ps is observed because of EIT. Pulse advance around 1200 ps is also demonstrated.

Difficulties in applying numerical simulations to an evaluation of occupational hazards caused by electromagnetic fields

PubMed Central

Zradziński, Patryk

2015-01-01

Due to the various physical mechanisms of interaction between a worker's body and the electromagnetic field at various frequencies, the principles of numerical simulations have been discussed for three areas of worker exposure: to low frequency magnetic field, to low and intermediate frequency electric field and to radiofrequency electromagnetic field. This paper presents the identified difficulties in applying numerical simulations to evaluate physical estimators of direct and indirect effects of exposure to electromagnetic fields at various frequencies. Exposure of workers operating a plastic sealer have been taken as an example scenario of electromagnetic field exposure at the workplace for discussion of those difficulties in applying numerical simulations. The following difficulties in reliable numerical simulations of workers’ exposure to the electromagnetic field have been considered: workers’ body models (posture, dimensions, shape and grounding conditions), working environment models (objects most influencing electromagnetic field distribution) and an analysis of parameters for which exposure limitations are specified in international guidelines and standards. PMID:26323781

Coupled structural, thermal, phase-change and electromagnetic analysis for superconductors, volume 1

NASA Technical Reports Server (NTRS)

Felippa, Carlos A.; Farhat, Charbel; Park, K. C.; Militello, Carmelo; Schuler, James J.

1993-01-01

This research program has dealt with the theoretical development and computer implementation of reliable and efficient methods for the analysis of coupled mechanical problems that involve the interaction of mechanical, thermal, phase-change and electromagnetic subproblems. The focus application has been the modeling of superconductivity and associated quantum-state phase-change phenomena. In support of this objective the work has addressed the following issues: (1) development of variational principles for finite elements; (2) finite element modeling of the electromagnetic problem; (3) coupling of thermal and mechanical effects; and (4) computer implementation and solution of the superconductivity transition problem. The research was carried out over the period September 1988 through March 1993. The main accomplishments have been: (1) the development of the theory of parametrized and gauged variational principles; (2) the application of those principled to the construction of electromagnetic, thermal and mechanical finite elements; and (3) the coupling of electromagnetic finite elements with thermal and superconducting effects; and (4) the first detailed finite element simulations of bulk superconductors, in particular the Meissner effect and the nature of the normal conducting boundary layer. The grant has fully supported the thesis work of one doctoral student (James Schuler, who started on January 1989 and completed on January 1993), and partly supported another thesis (Carmelo Militello, who started graduate work on January 1988 completing on August 1991). Twenty-three publications have acknowledged full or part support from this grant, with 16 having appeared in archival journals and 3 in edited books or proceedings.

Radio frequency tank eigenmode sensor for propellant quantity gauging

NASA Technical Reports Server (NTRS)

Zimmerli, Gregory A. (Inventor)

2013-01-01

A method for measuring the quantity of fluid in a tank may include the steps of selecting a match between a measured set of electromagnetic eigenfrequencies and a simulated plurality of sets of electromagnetic eigenfrequencies using a matching algorithm, wherein the match is one simulated set of electromagnetic eigenfrequencies from the simulated plurality of sets of electromagnetic eigenfrequencies, and determining the fill level of the tank based upon the match.

Three-Dimensional Simulations of Electron Beams Focused by Periodic Permanent Magnets

NASA Technical Reports Server (NTRS)

Kory, Carol L.

1999-01-01

A fully three-dimensional (3D) model of an electron beam focused by a periodic permanent magnet (PPM) stack has been developed. First, the simulation code MAFIA was used to model a PPM stack using the magnetostatic solver. The exact geometry of the magnetic focusing structure was modeled; thus, no approximations were made regarding the off-axis fields. The fields from the static solver were loaded into the 3D particle-in-cell (PIC) solver of MAFIA where fully 3D behavior of the beam was simulated in the magnetic focusing field. The PIC solver computes the time-integration of electromagnetic fields simultaneously with the time integration of the equations of motion of charged particles that move under the influence of those fields. Fields caused by those moving charges are also taken into account; thus, effects like space charge and magnetic forces between particles are fully simulated. The electron beam is simulated by a number of macro-particles. These macro-particles represent a given charge Q amounting to that of several million electrons in order to conserve computational time and memory. Particle motion is unrestricted, so particle trajectories can cross paths and move in three dimensions under the influence of 3D electric and magnetic fields. Correspondingly, there is no limit on the initial current density distribution of the electron beam, nor its density distribution at any time during the simulation. Simulation results including beam current density, percent ripple and percent transmission will be presented, and the effects current, magnetic focusing strength and thermal velocities have on beam behavior will be demonstrated using 3D movies showing the evolution of beam characteristics in time and space. Unlike typical beam optics models, this 3D model allows simulation of asymmetric designs such as non- circularly symmetric electrostatic or magnetic focusing as well as the inclusion of input/output couplers.

Particle simulation of plasmas on the massively parallel processor

NASA Technical Reports Server (NTRS)

Gledhill, I. M. A.; Storey, L. R. O.

1987-01-01

Particle simulations, in which collective phenomena in plasmas are studied by following the self consistent motions of many discrete particles, involve several highly repetitive sets of calculations that are readily adaptable to SIMD parallel processing. A fully electromagnetic, relativistic plasma simulation for the massively parallel processor is described. The particle motions are followed in 2 1/2 dimensions on a 128 x 128 grid, with periodic boundary conditions. The two dimensional simulation space is mapped directly onto the processor network; a Fast Fourier Transform is used to solve the field equations. Particle data are stored according to an Eulerian scheme, i.e., the information associated with each particle is moved from one local memory to another as the particle moves across the spatial grid. The method is applied to the study of the nonlinear development of the whistler instability in a magnetospheric plasma model, with an anisotropic electron temperature. The wave distribution function is included as a new diagnostic to allow simulation results to be compared with satellite observations.

Global linear gyrokinetic particle-in-cell simulations including electromagnetic effects in shaped plasmas

NASA Astrophysics Data System (ADS)

Mishchenko, A.; Borchardt, M.; Cole, M.; Hatzky, R.; Fehér, T.; Kleiber, R.; Könies, A.; Zocco, A.

2015-05-01

We give an overview of recent developments in electromagnetic simulations based on the gyrokinetic particle-in-cell codes GYGLES and EUTERPE. We present the gyrokinetic electromagnetic models implemented in the codes and discuss further improvements of the numerical algorithm, in particular the so-called pullback mitigation of the cancellation problem. The improved algorithm is employed to simulate linear electromagnetic instabilities in shaped tokamak and stellarator plasmas, which was previously impossible for the parameters considered.

Modeling and simulation of RF photoinjectors for coherent light sources

NASA Astrophysics Data System (ADS)

Chen, Y.; Krasilnikov, M.; Stephan, F.; Gjonaj, E.; Weiland, T.; Dohlus, M.

2018-05-01

We propose a three-dimensional fully electromagnetic numerical approach for the simulation of RF photoinjectors for coherent light sources. The basic idea consists in incorporating a self-consistent photoemission model within a particle tracking code. The generation of electron beams in the injector is determined by the quantum efficiency (QE) of the cathode, the intensity profile of the driving laser as well as by the accelerating field and magnetic focusing conditions in the gun. The total charge emitted during an emission cycle can be limited by the space charge field at the cathode. Furthermore, the time and space dependent electromagnetic field at the cathode may induce a transient modulation of the QE due to surface barrier reduction of the emitting layer. In our modeling approach, all these effects are taken into account. The beam particles are generated dynamically according to the local QE of the cathode and the time dependent laser intensity profile. For the beam dynamics, a tracking code based on the Lienard-Wiechert retarded field formalism is employed. This code provides the single particle trajectories as well as the transient space charge field distribution at the cathode. As an application, the PITZ injector is considered. Extensive electron bunch emission simulations are carried out for different operation conditions of the injector, in the source limited as well as in the space charge limited emission regime. In both cases, fairly good agreement between measurements and simulations is obtained.

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

Peratt, A.L.; Mostrom, M.A.

With the availability of 80--125 MHz microprocessors, the methodology developed for the simulation of problems in pulsed power and plasma physics on modern day supercomputers is now amenable to application on a wide range of platforms including laptops and workstations. While execution speeds with these processors do not match those of large scale computing machines, resources such as computer-aided-design (CAD) and graphical analysis codes are available to automate simulation setup and process data. This paper reports on the adaptation of IVORY, a three-dimensional, fully-electromagnetic, particle-in-cell simulation code, to this platform independent CAD environment. The primary purpose of this talk ismore » to demonstrate how rapidly a pulsed power/plasma problem can be scoped out by an experimenter on a dedicated workstation. Demonstrations include a magnetically insulated transmission line, power flow in a graded insulator stack, a relativistic klystron oscillator, and the dynamics of a coaxial thruster for space applications.« less

Simulation investigation of a Ku-band radial line oscillator operating at low guiding magnetic field

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

Dang, Fangchao, E-mail: dangfangchao@sina.com; Zhang, Xiaoping; Zhong, Huihuang

2014-06-15

A novel radial line oscillator operating at Ku-band with low guiding magnetic field is proposed in this paper. By using an oversized radial structure, the power handling capacity is enhanced significantly. Based on the small-signal theory, the π/2 mode in radial TM{sub 01} mode is selected as the working mode. Furthermore, a radial uniform guiding magnetic field, made up of four solenoids, is designed. As indicated in 2.5-dimensional fully electromagnetic particle-in-cell simulation, high power microwaves with a power of 2.2 GW and a frequency of 14.25 GHz are generated with over 40% efficiency when the electron beam voltage is 300 kV, themore » beam current 18 kA, and the guiding magnetic field is only 0.6 T. There is no angular non-asymmetric mode discovered in three-dimensional simulation.« less

An Attachable Electromagnetic Energy Harvester Driven Wireless Sensing System Demonstrating Milling-Processes and Cutter-Wear/Breakage-Condition Monitoring.

PubMed

Chung, Tien-Kan; Yeh, Po-Chen; Lee, Hao; Lin, Cheng-Mao; Tseng, Chia-Yung; Lo, Wen-Tuan; Wang, Chieh-Min; Wang, Wen-Chin; Tu, Chi-Jen; Tasi, Pei-Yuan; Chang, Jui-Wen

2016-02-23

An attachable electromagnetic-energy-harvester driven wireless vibration-sensing system for monitoring milling-processes and cutter-wear/breakage-conditions is demonstrated. The system includes an electromagnetic energy harvester, three single-axis Micro Electro-Mechanical Systems (MEMS) accelerometers, a wireless chip module, and corresponding circuits. The harvester consisting of magnets with a coil uses electromagnetic induction to harness mechanical energy produced by the rotating spindle in milling processes and consequently convert the harnessed energy to electrical output. The electrical output is rectified by the rectification circuit to power the accelerometers and wireless chip module. The harvester, circuits, accelerometer, and wireless chip are integrated as an energy-harvester driven wireless vibration-sensing system. Therefore, this completes a self-powered wireless vibration sensing system. For system testing, a numerical-controlled machining tool with various milling processes is used. According to the test results, the system is fully self-powered and able to successfully sense vibration in the milling processes. Furthermore, by analyzing the vibration signals (i.e., through analyzing the electrical outputs of the accelerometers), criteria are successfully established for the system for real-time accurate simulations of the milling-processes and cutter-conditions (such as cutter-wear conditions and cutter-breaking occurrence). Due to these results, our approach can be applied to most milling and other machining machines in factories to realize more smart machining technologies.

An Attachable Electromagnetic Energy Harvester Driven Wireless Sensing System Demonstrating Milling-Processes and Cutter-Wear/Breakage-Condition Monitoring

PubMed Central

Chung, Tien-Kan; Yeh, Po-Chen; Lee, Hao; Lin, Cheng-Mao; Tseng, Chia-Yung; Lo, Wen-Tuan; Wang, Chieh-Min; Wang, Wen-Chin; Tu, Chi-Jen; Tasi, Pei-Yuan; Chang, Jui-Wen

2016-01-01

An attachable electromagnetic-energy-harvester driven wireless vibration-sensing system for monitoring milling-processes and cutter-wear/breakage-conditions is demonstrated. The system includes an electromagnetic energy harvester, three single-axis Micro Electro-Mechanical Systems (MEMS) accelerometers, a wireless chip module, and corresponding circuits. The harvester consisting of magnets with a coil uses electromagnetic induction to harness mechanical energy produced by the rotating spindle in milling processes and consequently convert the harnessed energy to electrical output. The electrical output is rectified by the rectification circuit to power the accelerometers and wireless chip module. The harvester, circuits, accelerometer, and wireless chip are integrated as an energy-harvester driven wireless vibration-sensing system. Therefore, this completes a self-powered wireless vibration sensing system. For system testing, a numerical-controlled machining tool with various milling processes is used. According to the test results, the system is fully self-powered and able to successfully sense vibration in the milling processes. Furthermore, by analyzing the vibration signals (i.e., through analyzing the electrical outputs of the accelerometers), criteria are successfully established for the system for real-time accurate simulations of the milling-processes and cutter-conditions (such as cutter-wear conditions and cutter-breaking occurrence). Due to these results, our approach can be applied to most milling and other machining machines in factories to realize more smart machining technologies. PMID:26907297

Medium effect on the characteristics of the coupled seismic and electromagnetic signals.

PubMed

Huang, Qinghua; Ren, Hengxin; Zhang, Dan; Chen, Y John

2015-01-01

Recently developed numerical simulation technique can simulate the coupled seismic and electromagnetic signals for a double couple point source or a finite fault planar source. Besides the source effect, the simulation results showed that both medium structure and medium property could affect the coupled seismic and electromagnetic signals. The waveform of coupled signals for a layered structure is more complicated than that for a simple uniform structure. Different from the seismic signals, the electromagnetic signals are sensitive to the medium properties such as fluid salinity and fluid viscosity. Therefore, the co-seismic electromagnetic signals may be more informative than seismic signals.

Medium effect on the characteristics of the coupled seismic and electromagnetic signals

PubMed Central

HUANG, Qinghua; REN, Hengxin; ZHANG, Dan; CHEN, Y. John

2015-01-01

Recently developed numerical simulation technique can simulate the coupled seismic and electromagnetic signals for a double couple point source or a finite fault planar source. Besides the source effect, the simulation results showed that both medium structure and medium property could affect the coupled seismic and electromagnetic signals. The waveform of coupled signals for a layered structure is more complicated than that for a simple uniform structure. Different from the seismic signals, the electromagnetic signals are sensitive to the medium properties such as fluid salinity and fluid viscosity. Therefore, the co-seismic electromagnetic signals may be more informative than seismic signals. PMID:25743062

Design of a bounded wave EMP (Electromagnetic Pulse) simulator

NASA Astrophysics Data System (ADS)

Sevat, P. A. A.

1989-06-01

Electromagnetic Pulse (EMP) simulators are used to simulate the EMP generated by a nuclear weapon and to harden equipment against the effects of EMP. At present, DREO has a 1 m EMP simulator for testing computer terminal size equipment. To develop the R and D capability for testing larger objects, such as a helicopter, a much bigger threat level facility is required. This report concerns the design of a bounded wave EMP simulator suitable for testing large size equipment. Different types of simulators are described and their pros and cons are discussed. A bounded wave parallel plate type simulator is chosen for it's efficiency and the least environmental impact. Detailed designs are given for 6 m and 10 m parallel plate type wire grid simulators. Electromagnetic fields inside and outside the simulators are computed. Preliminary specifications for a pulse generator required for the simulator are also given. Finally, the electromagnetic fields radiated from the simulator are computed and discussed.

Fully Controllable Pancharatnam-Berry Metasurface Array with High Conversion Efficiency and Broad Bandwidth

PubMed Central

Liu, Chuanbao; Bai, Yang; Zhao, Qian; Yang, Yihao; Chen, Hongsheng; Zhou, Ji; Qiao, Lijie

2016-01-01

Metasurfaces have powerful abilities to manipulate the properties of electromagnetic waves flexibly, especially the modulation of polarization state for both linearly polarized (LP) and circularly polarized (CP) waves. However, the transmission efficiency of cross-polarization conversion by a single-layer metasurface has a low theoretical upper limit of 25% and the bandwidth is usually narrow, which cannot be resolved by their simple additions. Here, we efficiently manipulate polarization coupling in multilayer metasurface to promote the transmission of cross-polarization by Fabry-Perot resonance, so that a high conversion coefficient of 80–90% of CP wave is achieved within a broad bandwidth in the metasurface with C-shaped scatters by theoretical calculation, numerical simulation and experiments. Further, fully controlling Pancharatnam-Berry phase enables to realize polarized beam splitter, which is demonstrated to produce abnormal transmission with high conversion efficiency and broad bandwidth. PMID:27703254

The Impact of Computer Simulations as Interactive Demonstration Tools on the Performance of Grade 11 Learners in Electromagnetism

ERIC Educational Resources Information Center

Kotoka, Jonas; Kriek, Jeanne

2014-01-01

The impact of computer simulations on the performance of 65 grade 11 learners in electromagnetism in a South African high school in the Mpumalanga province is investigated. Learners did not use the simulations individually, but teachers used them as an interactive demonstration tool. Basic concepts in electromagnetism are difficult to understand…

Backward Raman Amplification in the Long-wavelength Infrared

DTIC Science & Technology

2016-12-29

mechanism for generating intense, broad bandwidth, long-wavelength infrared radiation. An electromagnetic finite-difference time-domain simulation...couples a finite-difference time-domain electromagnetic solver with a collisional, relativistic cold fluid plasma model [30]. The simulation domain... electromagnetic simulations coupled to a relativistic cold fluid plasma model with electron- ion collisions. Using a pump pulse that could be generated by a CO

Study on magnetic force of electromagnetic levitation circular knitting machine

NASA Astrophysics Data System (ADS)

Wu, X. G.; Zhang, C.; Xu, X. S.; Zhang, J. G.; Yan, N.; Zhang, G. Z.

2018-06-01

The structure of the driving coil and the electromagnetic force of the test prototype of electromagnetic-levitation (EL) circular knitting machine are studied. In this paper, the driving coil’s structure and working principle of the EL circular knitting machine are firstly introduced, then the mathematical modelling analysis of the driving electromagnetic force is carried out, and through the Ansoft Maxwell finite element simulation software the coil’s magnetic induction intensity and the needle’s electromagnetic force is simulated, finally an experimental platform is built to measure the coil’s magnetic induction intensity and the needle’s electromagnetic force. The results show that the theoretical analysis, the simulation analysis and the results of the test are very close, which proves the correctness of the proposed model.

Modeling of grain-oriented Si-steel and amorphous alloy iron core under ferroresonance using Jiles-Atherton hysteresis method

NASA Astrophysics Data System (ADS)

Sima, Wenxia; Zou, Mi; Yang, Ming; Yang, Qing; Peng, Daixiao

2018-05-01

Amorphous alloy is increasingly widely used in the iron core of power transformer due to its excellent low loss performance. However, its potential harm to the power system is not fully studied during the electromagnetic transients of the transformer. This study develops a simulation model to analyze the effect of transformer iron core materials on ferroresonance. The model is based on the transformer π equivalent circuit. The flux linkage-current (ψ-i) Jiles-Atherton reactor is developed in an Electromagnetic Transients Program-Alternative Transients Program and is used to represent the magnetizing branches of the transformer model. Two ferroresonance cases are studied to compare the performance of grain-oriented Si-steel and amorphous alloy cores. The ferroresonance overvoltage and overcurrent are discussed under different system parameters. Results show that amorphous alloy transformer generates higher voltage and current than those of grain-oriented Si-steel transformer and significantly harms the power system safety.

Electromagnetic Modeling of Human Body Using High Performance Computing

NASA Astrophysics Data System (ADS)

Ng, Cho-Kuen; Beall, Mark; Ge, Lixin; Kim, Sanghoek; Klaas, Ottmar; Poon, Ada

Realistic simulation of electromagnetic wave propagation in the actual human body can expedite the investigation of the phenomenon of harvesting implanted devices using wireless powering coupled from external sources. The parallel electromagnetics code suite ACE3P developed at SLAC National Accelerator Laboratory is based on the finite element method for high fidelity accelerator simulation, which can be enhanced to model electromagnetic wave propagation in the human body. Starting with a CAD model of a human phantom that is characterized by a number of tissues, a finite element mesh representing the complex geometries of the individual tissues is built for simulation. Employing an optimal power source with a specific pattern of field distribution, the propagation and focusing of electromagnetic waves in the phantom has been demonstrated. Substantial speedup of the simulation is achieved by using multiple compute cores on supercomputers.

Numerical characterization of a flexible circular coil for magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Bautista, T.; Hernandez, R.; Solis-Najera, S. E.; Rodriguez, A. O.

2012-10-01

Numerical simulations of the magnetic field generated by a flexible surface coil were conducted to study its behavior for applications of animal models at 7 Tesla. This coil design is able to fully cover a volume of interest. The Finite Difference Method in Time Domain (FDTD) was used because of its ability to accurately model complex problems in electromagnetism. This particular coil design is best suited for regions of interests with a spherical shape, since B1 uniformity is not significantly attenuated as in the case of a circular-loop coil. It still remains to investigate the feasibility to actually construct a coil prototype.

Binary neutron star mergers: a review of Einstein's richest laboratory.

PubMed

Baiotti, Luca; Rezzolla, Luciano

2017-09-01

In a single process, the merger of binary neutron star systems combines extreme gravity, the copious emission of gravitational waves, complex microphysics and electromagnetic processes, which can lead to astrophysical signatures observable at the largest redshifts. We review here the recent progress in understanding what could be considered Einstein's richest laboratory, highlighting in particular the numerous significant advances of the last decade. Although special attention is paid to the status of models, techniques and results for fully general-relativistic dynamical simulations, a review is also offered on the initial data and advanced simulations with approximate treatments of gravity. Finally, we review the considerable amount of work carried out on the post-merger phase, including black-hole formation, torus accretion onto the merged compact object, the connection with gamma-ray burst engines, ejected material, and its nucleosynthesis.

Binary neutron star mergers: a review of Einstein’s richest laboratory

NASA Astrophysics Data System (ADS)

Baiotti, Luca; Rezzolla, Luciano

2017-09-01

In a single process, the merger of binary neutron star systems combines extreme gravity, the copious emission of gravitational waves, complex microphysics and electromagnetic processes, which can lead to astrophysical signatures observable at the largest redshifts. We review here the recent progress in understanding what could be considered Einstein’s richest laboratory, highlighting in particular the numerous significant advances of the last decade. Although special attention is paid to the status of models, techniques and results for fully general-relativistic dynamical simulations, a review is also offered on the initial data and advanced simulations with approximate treatments of gravity. Finally, we review the considerable amount of work carried out on the post-merger phase, including black-hole formation, torus accretion onto the merged compact object, the connection with gamma-ray burst engines, ejected material, and its nucleosynthesis.

Detailed measurements of shower properties in a high granularity digital electromagnetic calorimeter

NASA Astrophysics Data System (ADS)

van der Kolk, N.

2018-03-01

The MAPS (Monolithic Active Pixel Sensors) prototype of the proposed ALICE Forward Calorimeter (FoCal) is the highest granularity electromagnetic calorimeter, with 39 million pixels with a size of 30 × 30 μm2. Particle showers can be studied with unprecedented detail with this prototype. Electromagnetic showers at energies between 2 GeV and 244 GeV have been studied and compared with GEANT4 simulations. Simulation models can be tested in more detail than ever before and the differences observed between FoCal data and GEANT4 simulations illustrate that improvements in electromagnetic models are still possible.

Three-Dimensional Electromagnetic Monte Carlo Particle-in-Cell Simulations of Critical Ionization Velocity Experiments in Space

NASA Technical Reports Server (NTRS)

Wang, J.; Biasca, R.; Liewer, P. C.

1996-01-01

Although the existence of the critical ionization velocity (CIV) is known from laboratory experiments, no agreement has been reached as to whether CIV exists in the natural space environment. In this paper we move towards more realistic models of CIV and present the first fully three-dimensional, electromagnetic particle-in-cell Monte-Carlo collision (PIC-MCC) simulations of typical space-based CIV experiments. In our model, the released neutral gas is taken to be a spherical cloud traveling across a magnetized ambient plasma. Simulations are performed for neutral clouds with various sizes and densities. The effects of the cloud parameters on ionization yield, wave energy growth, electron heating, momentum coupling, and the three-dimensional structure of the newly ionized plasma are discussed. The simulations suggest that the quantitative characteristics of momentum transfers among the ion beam, neutral cloud, and plasma waves is the key indicator of whether CIV can occur in space. The missing factors in space-based CIV experiments may be the conditions necessary for a continuous enhancement of the beam ion momentum. For a typical shaped charge release experiment, favorable CIV conditions may exist only in a very narrow, intermediate spatial region some distance from the release point due to the effects of the cloud density and size. When CIV does occur, the newly ionized plasma from the cloud forms a very complex structure due to the combined forces from the geomagnetic field, the motion induced emf, and the polarization. Hence the detection of CIV also critically depends on the sensor location.

Intense electromagnetic outbursts from collapsing hypermassive neutron stars

NASA Astrophysics Data System (ADS)

Lehner, Luis; Palenzuela, Carlos; Liebling, Steven L.; Thompson, Christopher; Hanna, Chad

2012-11-01

We study the gravitational collapse of a magnetized neutron star using a novel numerical approach able to capture both the dynamics of the star and the behavior of the surrounding plasma. In this approach, a fully general relativistic magnetohydrodynamics implementation models the collapse of the star and provides appropriate boundary conditions to a force-free model which describes the stellar exterior. We validate this strategy by comparing with known results for the rotating monopole and aligned rotator solutions and then apply it to study both rotating and nonrotating stellar collapse scenarios and contrast the behavior with what is obtained when employing the electrovacuum approximation outside the star. The nonrotating electrovacuum collapse is shown to agree qualitatively with a Newtonian model of the electromagnetic field outside a collapsing star. We illustrate and discuss a fundamental difference between the force-free and electrovacuum solutions, involving the appearance of large zones of electric-dominated field in the vacuum case. This provides a clear demonstration of how dissipative singularities appear generically in the nonlinear time evolution of force-free fluids. In both the rotating and nonrotating cases, our simulations indicate that the collapse induces a strong electromagnetic transient, which leaves behind an uncharged, unmagnetized Kerr black hole. In the case of submillisecond rotation, the magnetic field experiences strong winding, and the transient carries much more energy. This result has important implications for models of gamma-ray bursts. Even when the neutron star is surrounded by an accretion torus (as in binary merger and collapsar scenarios), a magnetosphere may emerge through a dynamo process operating in a surface shear layer. When this rapidly rotating magnetar collapses to a black hole, the electromagnetic energy released can compete with the later output in a Blandford-Znajek jet. Much less electromagnetic energy is released by a massive magnetar that is (initially) gravitationally stable: its rotational energy is dissipated mainly by internal torques. A distinct plasmoid structure is seen in our nonrotating simulations, which will generate a radio transient with subluminal expansion and greater synchrotron efficiency than is expected in shock models. Closely related phenomena appear to be at work in the giant flares of Galactic magnetars.

ALEGRA-MHD Simulations for Magnetization of an Ellipsoidal Inclusion

DTIC Science & Technology

2017-08-01

diffusion has saturated. The simplicity of the interior solution lends itself well to verification of computational electromagnetic simulations...magnetic diffusion, permeability, computational electromagnetism , verification, magnetohydrodynamics 16. SECURITY CLASSIFICATION OF: 17. LIMITATION... electromagnetic phenomena including magnetohydrodynamics (MHD). This multiphysics capability is a key feature of ALEGRA and the result of many years of

Micro-patterning of resin-bonded NdFeB magnet for a fully integrated electromagnetic actuator

NASA Astrophysics Data System (ADS)

Tao, Kai; Wu, Jin; Kottapalli, Ajay Giri Prakash; Chen, Di; Yang, Zhuoqing; Ding, Guifu; Lye, Sun Woh; Miao, Jianmin

2017-12-01

This paper reports a fully-integrated, batch-fabricated electromagnetic actuator which features micro-patterned NdFeB magnets. The entire actuator is fabricated through MEMS-compatible laminated surface micromachining technology, eliminating the requirement for further component assembly processes. The fabrication strategy allowed the entire volume of the actuator to be reduced to a small size of 2.5 × 2.5 × 2 mm3, which is one of the smallest NdFeB-based electromagnetic actuators demonstrated to date. The magnetic properties of NdFeB thin films are further investigated and optimized using different types of lithographically-defined micromolds. By altering the direction of the input current, actuating displacements of approximately ±10 μm are achieved during both the attraction and the repulsion operations. This work demonstrates the viability and compatibility of using polymer-bonded magnets for magnetic MEMS applications.

Kinetic Simulations of Type II Radio Burst Emission Processes

NASA Astrophysics Data System (ADS)

Ganse, U.; Spanier, F. A.; Vainio, R. O.

2011-12-01

The fundamental emission process of Type II Radio Bursts has been under discussion for many decades. While analytic deliberations point to three wave interaction as the source for fundamental and harmonic radio emissions, sparse in-situ observational data and high computational demands for kinetic simulations have not allowed for a definite conclusion to be reached. A popular model puts the radio emission into the foreshock region of a coronal mass ejection's shock front, where shock drift acceleration can create eletrcon beam populations in the otherwise quiescent foreshock plasma. Beam-driven instabilities are then assumed to create waves, forming the starting point of three wave interaction processes. Using our kinetic particle-in-cell code, we have studied a number of emission scenarios based on electron beam populations in a CME foreshock, with focus on wave-interaction microphysics on kinetic scales. The self-consistent, fully kinetic simulations with completely physical mass-ratio show fundamental and harmonic emission of transverse electromagnetic waves and allow for detailled statistical analysis of all contributing wavemodes and their couplings.

Kinetic simulations of gas breakdown in the dense plasma focus

DOE PAGES

Bennett, N.; Blasco, M.; Breeding, K.; ...

2017-06-09

We describe the first fully-kinetic, collisional, and electromagnetic simulations of the breakdown phase of a MA-scale dense plasma focus and are shown to agree with measured electrical characteristics, including breakdown time. In the model, avalanche ionization is driven by cathode electron emission and this results in incomplete gas breakdown along the insulator. This reinforces the importance of the conditioning process that creates a metallic layer on the insulator surface. The simulations, nonetheless, help explain the relationship between the gas pressure, the insulator length, and the coaxial gap width. In the past, researchers noted three breakdown patterns related to pressure. Simulationmore » and analytic results show that at low pressures, long ionization path lengths lead to volumetric breakdown, while high pressures lead to breakdown across the relatively small coaxial electrode gap. In an intermediate pressure regime, ionization path lengths are comparable to the insulator length which promotes ideal breakdown along the insulator surface.« less

Particle-in-cell simulations of the lower-hybrid instability driven by an ion-ring distribution

NASA Astrophysics Data System (ADS)

Swanekamp, Stephen; Richardson, Steve; Mithaiwala, Manish; Crabtree, Chris

2013-10-01

Fully electromagnetic particle-in-cell simulations of the excitation of the lower-hybrid mode in a plasma driven by an ion-ring distribution using the Lsp code are presented. At early times the simulations agree with linear theory. The resulting wave evolution and non-linear plasma and ring-ion heating are compared with theoretical models [Mithaiwala et al. 2010; Crabtree et al., this meeting] and previous simulation results [Winske and Daughton, 2012]. 2D simulations show that when the magnetic field is perpendicular to the wave vector, k, the electrostatic potential fluctuations work in conjunction with the applied magnetic field causing a circular electron E ×B drift around a positively charged center. Similar phenomena are observed in 2D simulations of magnetic-field penetration into a spatially inhomogeneous unmagnetized plasma [Richardson et al., this meeting] where circular paramagnetic vortices are formed. These vortices are altered by the addition of a small, in-plane, component of magnetic field which allows electrons to stream along field lines effectively shorting out one component of the electric field. In this case, the vortex structures are no longer circular but elongated along the direction of the in-plane magnetic field component.

New VHP-Female v. 2.0 full-body computational phantom and its performance metrics using FEM simulator ANSYS HFSS.

PubMed

Yanamadala, Janakinadh; Noetscher, Gregory M; Rathi, Vishal K; Maliye, Saili; Win, Htay A; Tran, Anh L; Jackson, Xavier J; Htet, Aung T; Kozlov, Mikhail; Nazarian, Ara; Louie, Sara; Makarov, Sergey N

2015-01-01

Simulation of the electromagnetic response of the human body relies heavily upon efficient computational models or phantoms. The first objective of this paper is to present a new platform-independent full-body electromagnetic computational model (computational phantom), the Visible Human Project(®) (VHP)-Female v. 2.0 and to describe its distinct features. The second objective is to report phantom simulation performance metrics using the commercial FEM electromagnetic solver ANSYS HFSS.

Characterizing Hypervelocity Impact Plasma Through Experiments and Simulations

NASA Astrophysics Data System (ADS)

Close, Sigrid; Lee, Nicolas; Fletcher, Alex; Nuttall, Andrew; Hew, Monica; Tarantino, Paul

2017-10-01

Hypervelocity micro particles, including meteoroids and space debris with masses <1 ng, routinely impact spacecraft and create dense plasma that expands at the isothermal sound speed. This plasma, with a charge separation commensurate with different species mobilities, can produce a strong electromagnetic pulse (EMP) with a broad frequency spectrum. Subsequent plasma oscillations resulting from instabilities can also emit significant power and may be responsible for many reported satellite anomalies. We present theory and recent results from ground-based impact tests aimed at characterizing hypervelocity impact plasma. We also show results from particle-in-cell (PIC) and computational fluid dynamics (CFD) simulations that allow us to extend to regimes not currently possible with ground-based technology. We show that significant impact-produced radio frequency (RF) emissions occurred in frequencies ranging from VHF through L-band and that these emissions were highly correlated with fast (>20 km/s) impacts that produced a fully ionized plasma.

Real-time visualization of magnetic flux densities for transcranial magnetic stimulation on commodity and fully immersive VR systems

NASA Astrophysics Data System (ADS)

Kalivarapu, Vijay K.; Serrate, Ciro; Hadimani, Ravi L.

2017-05-01

Transcranial Magnetic Stimulation (TMS) is a non-invasive procedure that uses time varying short pulses of magnetic fields to stimulate nerve cells in the brain. In this method, a magnetic field generator ("TMS coil") produces small electric fields in the region of the brain via electromagnetic induction. This technique can be used to excite or inhibit firing of neurons, which can then be used for treatment of various neurological disorders such as Parkinson's disease, stroke, migraine, and depression. It is however challenging to focus the induced electric field from TMS coils to smaller regions of the brain. Since electric and magnetic fields are governed by laws of electromagnetism, it is possible to numerically simulate and visualize these fields to accurately determine the site of maximum stimulation and also to develop TMS coils that can focus the fields on the targeted regions. However, current software to compute and visualize these fields are not real-time and can work for only one position/orientation of TMS coil, severely limiting their usage. This paper describes the development of an application that computes magnetic flux densities (h-fields) and visualizes their distribution for different TMS coil position/orientations in real-time using GPU shaders. The application is developed for desktop, commodity VR (HTC Vive), and fully immersive VR CAVETM systems, for use by researchers, scientists, and medical professionals to quickly and effectively view the distribution of h-fields from MRI brain scans.

Synthetic electromagnetic knot in a three-dimensional skyrmion

PubMed Central

Lee, Wonjae; Gheorghe, Andrei H.; Tiurev, Konstantin; Ollikainen, Tuomas; Möttönen, Mikko; Hall, David S.

2018-01-01

Classical electromagnetism and quantum mechanics are both central to the modern understanding of the physical world and its ongoing technological development. Quantum simulations of electromagnetic forces have the potential to provide information about materials and systems that do not have conveniently solvable theoretical descriptions, such as those related to quantum Hall physics, or that have not been physically observed, such as magnetic monopoles. However, quantum simulations that simultaneously implement all of the principal features of classical electromagnetism have thus far proved elusive. We experimentally realize a simulation in which a charged quantum particle interacts with the knotted electromagnetic fields peculiar to a topological model of ball lightning. These phenomena are induced by precise spatiotemporal control of the spin field of an atomic Bose-Einstein condensate, simultaneously creating a Shankar skyrmion—a topological excitation that was theoretically predicted four decades ago but never before observed experimentally. Our results reveal the versatile capabilities of synthetic electromagnetism and provide the first experimental images of topological three-dimensional skyrmions in a quantum system. PMID:29511735

High-order Two-Fluid Plasma Solver for Direct Numerical Simulations of Magnetic Flows with Realistic Transport Phenomena

NASA Astrophysics Data System (ADS)

Li, Zhaorui; Livescu, Daniel

2017-11-01

The two-fluid plasma equations with full transport terms, including temperature and magnetic field dependent ion and electron viscous stresses and heat fluxes, frictional drag force, and ohmic heating term have been solved by using the sixth-order non-dissipative compact scheme for plasma flows in several different regimes. In order to be able to fully resolve all the dynamically relevant time and length scales while maintaining computational feasibility, the assumptions of infinite speed of light and negligible electron inertia have been made. The accuracy and robustness of this two-fluid plasma solver in handling plasma flows have been tested against a series of canonical problems, such as Alfven-Whistler dispersion relation, electromagnetic plasma shock, magnetic reconnection, etc. For all test cases, grid convergence tests have been conducted to achieve fully resolved results. The roles of heat flux, viscosity, resistivity, Hall and Biermann battery effects, are investigated for the canonical flows studied.

Toward a Time-Domain Fractal Lightning Simulation

NASA Astrophysics Data System (ADS)

Liang, C.; Carlson, B. E.; Lehtinen, N. G.; Cohen, M.; Lauben, D.; Inan, U. S.

2010-12-01

Electromagnetic simulations of lightning are useful for prediction of lightning properties and exploration of the underlying physical behavior. Fractal lightning models predict the spatial structure of the discharge, but thus far do not provide much information about discharge behavior in time and therefore cannot predict electromagnetic wave emissions or current characteristics. Here we develop a time-domain fractal lightning simulation from Maxwell's equations, the method of moments with the thin wire approximation, an adaptive time-stepping scheme, and a simplified electrical model of the lightning channel. The model predicts current pulse structure and electromagnetic wave emissions and can be used to simulate the entire duration of a lightning discharge. The model can be used to explore the electrical characteristics of the lightning channel, the temporal development of the discharge, and the effects of these characteristics on observable electromagnetic wave emissions.

Calibration of the LHAASO-KM2A electromagnetic particle detectors using charged particles within the extensive air showers

NASA Astrophysics Data System (ADS)

Lv, Hongkui; He, Huihai; Sheng, Xiangdong; Liu, Jia; Chen, Songzhan; Liu, Ye; Hou, Chao; Zhao, Jing; Zhang, Zhongquan; Wu, Sha; Wang, Yaping; Lhaaso Collaboration

2018-07-01

In the Large High Altitude Air Shower Observatory (LHAASO), one square kilometer array (KM2A), with 5242 electromagnetic particle detectors (EDs) and 1171 muon detectors (MDs), is designed to study ultra-high energy gamma-ray astronomy and cosmic ray physics. The remoteness and numerous detectors extremely demand a robust and automatic calibration procedure. In this paper, a self-calibration method which relies on the measurement of charged particles within the extensive air showers is proposed. The method is fully validated by Monte Carlo simulation and successfully applied in a KM2A prototype array experiment. Experimental results show that the self-calibration method can be used to determine the detector time offset constants at the sub-nanosecond level and the number density of particles collected by each ED with an accuracy of a few percents, which are adequate to meet the physical requirements of LHAASO experiment. This software calibration also offers an ideal method to realtime monitor the detector performances for next generation ground-based EAS experiments covering an area above square kilometers scale.

Electromagnetic Design of a Magnetically-Coupled Spatial Power Combiner

NASA Technical Reports Server (NTRS)

Bulcha, B.; Cataldo, G.; Stevenson, T. R.; U-Yen, K.; Moseley, S. H.; Wollack, E. J.

2017-01-01

The design of a two-dimensional beam-combining network employing a parallel-plate superconducting waveguide with a mono-crystalline silicon dielectric is presented. This novel beam-combining network structure employs an array of magnetically coupled antenna elements to achieve high coupling efficiency and full sampling of the intensity distribution while avoiding diffractive losses in the multi-mode region defined by the parallel-plate waveguide. These attributes enable the structures use in realizing compact far-infrared spectrometers for astrophysical and instrumentation applications. When configured with a suitable corporate-feed power-combiner, this fully sampled array can be used to realize a low-sidelobe apodized response without incurring a reduction in coupling efficiency. To control undesired reflections over a wide range of angles in the finite-sized parallel-plate waveguide region, a wideband meta-material electromagnetic absorber structure is implemented. This adiabatic structure absorbs greater than 99 of the power over the 1.7:1 operational band at angles ranging from normal (0 degree) to near parallel (180 degree) incidence. Design, simulations, and application of the device will be presented.

Design of a mobile, homogeneous, and efficient electromagnet with a large field of view for neonatal low-field MRI.

PubMed

Lother, Steffen; Schiff, Steven J; Neuberger, Thomas; Jakob, Peter M; Fidler, Florian

2016-08-01

In this work, a prototype of an effective electromagnet with a field-of-view (FoV) of 140 mm for neonatal head imaging is presented. The efficient implementation succeeded by exploiting the use of steel plates as a housing system. We achieved a compromise between large sample volumes, high homogeneity, high B0 field, low power consumption, light weight, simple fabrication, and conserved mobility without the necessity of a dedicated water cooling system. The entire magnetic resonance imaging (MRI) system (electromagnet, gradient system, transmit/receive coil, control system) is introduced and its unique features discussed. Furthermore, simulations using a numerical optimization algorithm for magnet and gradient system are presented. Functionality and quality of this low-field scanner operating at 23 mT (generated with 500 W) is illustrated using spin-echo imaging (in-plane resolution 1.6 mm × 1.6 mm, slice thickness 5 mm, and signal-to-noise ratio (SNR) of 23 with a acquisition time of 29 min). B0 field-mapping measurements are presented to characterize the homogeneity of the magnet, and the B0 field limitations of 80 mT of the system are fully discussed. The cryogen-free system presented here demonstrates that this electromagnet with a ferromagnetic housing can be optimized for MRI with an enhanced and homogeneous magnetic field. It offers an alternative to prepolarized MRI designs in both readout field strength and power use. There are multiple indications for the clinical medical application of such low-field devices.

Design of a mobile, homogeneous, and efficient electromagnet with a large field of view for neonatal low-field MRI

PubMed Central

Schiff, Steven J.; Neuberger, Thomas; Jakob, Peter M.; Fidler, Florian

2017-01-01

Objective In this work, a prototype of an effective electromagnet with a field-of-view (FoV) of 140 mm for neonatal head imaging is presented. The efficient implementation succeeded by exploiting the use of steel plates as a housing system. We achieved a compromise between large sample volumes, high homogeneity, high B0 field, low power consumption, light weight, simple fabrication, and conserved mobility without the necessity of a dedicated water cooling system. Materials and methods The entire magnetic resonance imaging (MRI) system (electromagnet, gradient system, transmit/receive coil, control system) is introduced and its unique features discussed. Furthermore, simulations using a numerical optimization algorithm for magnet and gradient system are presented. Results Functionality and quality of this low-field scanner operating at 23 mT (generated with 500 W) is illustrated using spin-echo imaging (in-plane resolution 1.6 mm × 1.6 mm, slice thickness 5 mm, and signal-to-noise ratio (SNR) of 23 with a acquisition time of 29 min). B0 field-mapping measurements are presented to characterize the homogeneity of the magnet, and the B0 field limitations of 80 mT of the system are fully discussed. Conclusion The cryogen-free system presented here demonstrates that this electromagnet with a ferromagnetic housing can be optimized for MRI with an enhanced and homogeneous magnetic field. It offers an alternative to pre-polarized MRI designs in both readout field strength and power use. There are multiple indications for the clinical medical application of such low-field devices. PMID:26861046

THz electromagnetic radiation driven by intense relativistic electron beam based on ion focus regime

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

Zhou, Qing; Xu, Jin; Zhang, Wenchao

The simulation study finds that the relativistic electron beam propagating through the plasma background can produce electromagnetic (EM) radiation. With the propagation of the electron beam, the oscillations of the beam electrons in transverse and longitudinal directions have been observed simultaneously, which provides the basis for the electromagnetic radiation. The simulation results clearly show that the electromagnetic radiation frequency can reach up to terahertz (THz) wave band which may result from the filter-like property of plasma background, and the electromagnetic radiation frequency closely depends on the plasma density. To understand the above simulation results physically, the dispersion relation of themore » beam-plasma system has been derived using the field-matching method, and the dispersion curves show that the slow wave modes can couple with the electron beam effectively in THz wave band, which is an important theoretical evidence of the EM radiation.« less

Quasi-static modeling of beam-plasma and laser-plasma interactions

NASA Astrophysics Data System (ADS)

Huang, Chengkun

Plasma wave wakefields excited by either laser or particle beams can sustain acceleration gradients three orders of magnitude larger than conventional RF accelerators. They are promising for accelerating particles in short distances for applications such as future high-energy colliders, and medical and industrial accelerators. In a Plasma Wakefield Accelerator (PWFA) or a Laser Wakefield Accelerator (LWFA), an intense particle or laser beam drives a plasma wave and generates a strong wakefield which has a phase velocity equal to the velocity of the driver. This wakefield can then be used to accelerate part of the drive beam or a separate trailing beam. The interaction between the plasma and the driver is highly nonlinear and therefore a particle description is required for computer modeling. A highly efficient, fully parallelized, fully relativistic, three-dimensional particle-in-cell code called QuickPIC for simulating plasma and laser wakefield acceleration has been developed. The model is based on the quasi-static or frozen field approximation, which assumes that the drive beam and/or the laser does not evolve during the time it takes for it to pass a plasma particle. The electromagnetic fields of the plasma wake and its associated index of refraction are then used to evolve the driver using very large time steps. This algorithm reduces the computational time by at least 2 to 3 orders of magnitude. Comparison between the new algorithm and a fully explicit model (OSIRIS) are presented. The agreement is excellent for problems of interest. Direction for future work is also discussed. QuickPIC has been used to study the "afterburner" concept. In this concept a fraction of an existing high-energy beam is separated out and used as a trailing beam with the goal that the trailing beam acquires at least twice the energy of the drive beam. Several critical issues such as the efficient transfer of energy and the stable propagation of both the drive and trailing beams in the plasma are investigated. We have simulated a 100 GeV and a 1 TeV plasma "afterburner" stages for electron beams and the results are presented. QuickPIC also has enabled us to develop a new theory for understanding the hosing instability of the drive and trailing beams. The new theory is based on a perturbation to the ion column boundary which includes relativistic effects, axial motion and the full electromagnetic character of the wake. The new theory is verified by comparing it to the simulation results. In the adiabatic long beam limit it recovers the result of previous work from fluid models.

Three-dimensional particle-in-cell simulations of a plasma jet/cloud streaming across a transverse magnetic field

NASA Astrophysics Data System (ADS)

Voitcu, Gabriel; Echim, Marius

2014-05-01

The dynamics of collisionless plasma jets/clouds in magnetic field configurations typical for the terrestrial magnetotail and frontside magnetosheath is a topic of interest for understanding the physics of the magnetosphere and its interaction with the solar wind. The presence of high-speed jets in the frontside magnetosheath has been recently proved experimentally by Cluster and THEMIS spacecrafts. There is increasing evidence that the bursty bulk flows in the magnetotail have jet-like features. In the present paper we use fully electromagnetic 3D explicit particle-in-cell (PIC) simulations to investigate the interaction of a localized three-dimensional plasma element/jet/cloud with a transverse magnetic field. We consider a plasma jet/cloud that moves in vacuum and perpendicular to an ambient magnetic field. Ampère and Faraday's laws are used to compute the self-consistent electric and magnetic fields on a three-dimensional spatial grid having a step-size of the order of the Debye length and using a time-step that resolves the plasma frequency. The initial magnetic field inside the simulation domain is uniform and the plasma bulk velocity at the beginning of the simulation is normal to the magnetic field direction. The total time scale of the simulation is of the order of few ion Larmor periods. Space and time variations of the plasma parameters and of the electromagnetic field are analyzed and discussed. We emphasize non-MHD effects like the energy-dispersion signatures at the edges of the plasma element, similar to results previously reported by Voitcu and Echim (2012) using test-kinetic simulations. Acknowledgments: Research supported by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 313038/STORM, and a grant of the Romanian Ministry of National Education, CNCS - UEFISCDI, project number PN-II-ID-PCE-2012-4-0418.

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.

Electromagnetic fields in curved spacetimes

NASA Astrophysics Data System (ADS)

Tsagas, Christos G.

2005-01-01

We consider the evolution of electromagnetic fields in curved spacetimes and calculate the exact wave equations for the associated electric and magnetic components. Our analysis is fully covariant, applies to a general spacetime and isolates all the sources that affect the propagation of these waves. Among others, we explicitly show how the different components of the gravitational field act as driving sources of electromagnetic disturbances. When applied to perturbed Friedmann Robertson Walker cosmologies, our results argue for a superadiabatic-type amplification of large-scale cosmological magnetic fields in Friedmann models with open spatial curvature.

Development of Simulated Disturbing Source for Isolation Switch

NASA Astrophysics Data System (ADS)

Cheng, Lin; Liu, Xiang; Deng, Xiaoping; Pan, Zhezhe; Zhou, Hang; Zhu, Yong

2018-01-01

In order to simulate the substation in the actual scene of the harsh electromagnetic environment, and then research on electromagnetic compatibility testing of electronic instrument transformer, On the basis of the original isolation switch as a harassment source of the electronic instrument transformer electromagnetic compatibility test system, an isolated switch simulation source system was developed, to promote the standardization of the original test. In this paper, the circuit breaker is used to control the opening and closing of the gap arc to simulate the operating of isolating switch, and the isolation switch simulation harassment source system is designed accordingly. Comparison with the actual test results of the isolating switch, it is proved that the system can meet the test requirements, and the simulation harassment source system has good stability and high reliability.

Optically transparent microwave screens based on engineered graphene layers.

PubMed

Grande, M; Bianco, G V; Vincenti, M A; de Ceglia, D; Capezzuto, P; Petruzzelli, V; Scalora, M; Bruno, G; D'Orazio, A

2016-10-03

We propose an innovative approach for the realization of a microwave absorber fully transparent in the optical regime. This device is based on the Salisbury screen configuration, which consists of a lossless spacer, sandwiched between two graphene sheets whose sheet resistances are different and properly engineered. Experimental results show that it is possible to achieve near-perfect electromagnetic absorption in the microwave X-band. These findings are fully supported by an analytical approach based on an equivalent circuital model. Engineering and integration of graphene sheets could facilitate the realization of innovative microwave absorbers with additional electromagnetic and optical functionalities that could circumvent some of the major limitations of opaque microwave absorbers.

The singing comet 67P: utilizing fully kinetic simulations to study its interaction with the solar wind plasma

NASA Astrophysics Data System (ADS)

Deca, J.; Divin, A. V.; Horanyi, M.; Henri, P.

2016-12-01

We present preliminary results of the first 3-D fully kinetic and electromagnetic simulations of the solar wind interaction with 67P/Churyumov-Gerasimenko at 3 AU, before the comet transitions into its high-activity phase. We focus on the global cometary environment and the electron-kinetic activity of the interaction. In addition to the background solar wind plasma flow, our model includes also plasma-driven ionization of cometary neutrals and collisional effects. We approximate mass loading of cold cometary oxygen and hydrogen using a hyperbolic relation with distance to the comet. We consider two primary cases: a weak outgassing comet (with the peak ion density 10x the solar wind density) and a moderately outgassing comet (with the peak ion density 50x the solar wind density). The weak comet is characterized by the formation of a narrow region containing a compressed solar wind (the density of the solar wind ion population is 3x the value far upstream of the comet) and a magnetic barrier ( 2x to 4x the interplanetary magnetic field). Blobs of plasma are detached continuously from this sheath region. Standing electromagnetic waves are excited in the cometary wake due to a strong anisotropy in the plasma pressure, as the density and the magnetic field magnitude are anti-correlated.The moderate mass-loading case shows more dynamics at the dayside region. The stagnation of the solar wind flow is accompanied by the formation of elongated density stripes, indicating the presence of a Rayleigh-Taylor instability. These density cavities are elongated in the direction of the magnetic field and encompass the dayside ionopause. To conclude, we believe that our results provide vital information to disentangle the observations made by the Rosetta spacecraft and compose a global solar wind - comet interaction model.

Numerical Simulation of Electromagnetic Field Variation in the Lithosphere-Atmosphere-Ionosphere Associated with Seismogenic Process in a Curvature Coordinate System

NASA Astrophysics Data System (ADS)

Liu, L.; Zhao, Z.; Wang, Y.; Huang, Q.

2013-12-01

The lithosphere-atmosphere- ionosphere (LAI) system formed an electromagnetic (EM) cavity that hosts the EM field excited by electric currents generated by lightning and other natural sources. There have also been numerous reports on variations of the EM field existing in LAI system prior to some significance earthquakes. We simulated the EM field in the lithosphere-ionosphere waveguide with a whole-earth model using a curvature coordinate by the hybrid pseudo-spectral and finite difference time domain method. Considering the seismogensis as a fully coupled seismoelectric process, we simulate the seismic wave and the EM wave in this 2D model. In the model we have observed the excitation of the Schumann Resonance (SR) as the background EM field generated by randomly placed electric-current impulses within the lowest 10 kilometers of the atmosphere. The diurnal variation and the latitude-dependence in ion concentration in the ionosphere are included in the model. After the SR reaching a steady state, an electric impulse is introduced in the shallow lithosphere to mimic the seismogenic process (pre-, co- and post-seismic) to assess the possible precursory effects on SR strength and frequency. The modeling results can explain the observed fact of why SR has a much more sensitive response to continental earthquakes, and much less response to oceanic events. The fundamental reason is simply due to the shielding effect of the conductive ocean that prevents effective radiation of the seismoelectric signals from oceanic earthquake events into the LAI waveguide.

Fast Simulation of Electromagnetic Showers in the ATLAS Calorimeter: Frozen Showers

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

Barberio, E.; /Melbourne U.; Boudreau, J.

2011-11-29

One of the most time consuming process simulating pp interactions in the ATLAS detector at LHC is the simulation of electromagnetic showers in the calorimeter. In order to speed up the event simulation several parametrisation methods are available in ATLAS. In this paper we present a short description of a frozen shower technique, together with some recent benchmarks and comparison with full simulation. An expected high rate of proton-proton collisions in ATLAS detector at LHC requires large samples of simulated events (Monte Carlo) to study various physics processes. A detailed simulation of particle reactions ('full simulation') in the ATLAS detectormore » is based on GEANT4 and is very accurate. However, due to complexity of the detector, high particle multiplicity and GEANT4 itself, the average CPU time spend to simulate typical QCD event in pp collision is 20 or more minutes for modern computers. During detector simulation the largest time is spend in the calorimeters (up to 70%) most of which is required for electromagnetic particles in the electromagnetic (EM) part of the calorimeters. This is the motivation for fast simulation approaches which reduce the simulation time without affecting the accuracy. Several of fast simulation methods available within the ATLAS simulation framework (standard Athena based simulation program) are discussed here with the focus on the novel frozen shower library (FS) technique. The results obtained with FS are presented here as well.« less

Research on radiation characteristic of plasma antenna through FDTD method.

PubMed

Zhou, Jianming; Fang, Jingjing; Lu, Qiuyuan; Liu, Fan

2014-01-01

The radiation characteristic of plasma antenna is investigated by using the finite-difference time-domain (FDTD) approach in this paper. Through using FDTD method, we study the propagation of electromagnetic wave in free space in stretched coordinate. And the iterative equations of Maxwell equation are derived. In order to validate the correctness of this method, we simulate the process of electromagnetic wave propagating in free space. Results show that electromagnetic wave spreads out around the signal source and can be absorbed by the perfectly matched layer (PML). Otherwise, we study the propagation of electromagnetic wave in plasma by using the Boltzmann-Maxwell theory. In order to verify this theory, the whole process of electromagnetic wave propagating in plasma under one-dimension case is simulated. Results show that Boltzmann-Maxwell theory can be used to explain the phenomenon of electromagnetic wave propagating in plasma. Finally, the two-dimensional simulation model of plasma antenna is established under the cylindrical coordinate. And the near-field and far-field radiation pattern of plasma antenna are obtained. The experiments show that the variation of electron density can introduce the change of radiation characteristic.

Propagation of electromagnetic waves in a weak collisional and fully ionized dusty plasma

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

Jia, Jieshu; Yuan, Chengxun, E-mail: yuancx@hit.edu.cn; Gao, Ruilin

2016-04-15

The propagation properties of electromagnetic (EM) waves in fully ionized dusty plasmas is the subject of this study. The dielectric relationships for EM waves propagating in a fully ionized dusty plasma was derived from the Boltzmann distribution law, taking into consideration the collision and charging effects of the dust grains. The propagation properties of the EM waves in a dusty plasma were numerically calculated and studied. The study results indicated that the dusty grains with an increased radius and charge were more likely to impede the penetration of EM waves. Dust grains with large radii and high charge cause themore » attenuation of the EM wave in the dusty plasma. The different density of the dust in the plasma appeared to have no obvious effect on the transmission of the EM waves. The propagation of the EM waves in a weakly ionized dusty plasma varies from that in a fully ionized dusty plasma. The results are helpful to analyze the effects of dust in dusty plasmas and also provide a theoretical basis for future studies.« less

Modeling and simulation research on electromagnetic and energy-recycled damper based on Adams

NASA Astrophysics Data System (ADS)

Zhou, C. F.; Zhang, K.; Zhang, Pengfei

2018-05-01

In order to study the voltage and power output characteristics of the electromagnetic and energy-recycled damper which consists of gear, rack and generator, the Adams model of this damper and the Simulink model of generator are established, and the co-simulation is accomplished with these two models. The output indexes such as the gear speed and power of generator are obtained by the simulation, and the simulation results demonstrate that the voltage peak of the damper is 25 V; the maximum output power of the damper is 8 W. The above research provides a basis for the prototype development of electromagnetic and energy-recycled damper with gear and rack.

Electromagnetic Simulations for Aerospace Application Final Report CRADA No. TC-0376-92

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

Madsen, N.; Meredith, S.

Electromagnetic (EM) simulation tools play an important role in the design cycle, allowing optimization of a design before it is fabricated for testing. The purpose of this cooperative project was to provide Lockheed with state-of-the-art electromagnetic (EM) simulation software that will enable the optimal design of the next generation of low-observable (LO) military aircraft through the VHF regime. More particularly, the project was principally code development and validation, its goal to produce a 3-D, conforming grid,time-domain (TD) EM simulation tool, consisting of a mesh generator, a DS13D-based simulation kernel, and an RCS postprocessor, which was useful in the optimization ofmore » LO aircraft, both for full-aircraft simulations run on a massively parallel computer and for small scale problems run on a UNIX workstation.« less

Variation of Electric Properties Between Surface Permanent Magnet and Interior Permanent Magnet Motor

NASA Astrophysics Data System (ADS)

Woo, Byung-Chul; Hong, Do-Kwan; Lee, Ji-Young

The most distinctive advantage of transverse flux motor(TFM) is high torque density which has prompted many researches into studying various design variants. TFM is well suited for low speed direct drive applications due to its high torque density. This paper deals with simulation based comparisons between a surface permanent magnet transverse flux motor(SPM-TFM) and an interior permanent magnet transverse flux motor(IPM-TFM). A commercial finite element analysis(FEA) software Maxwell 3D is used for electromagnetic field computation to fully analyze complex geometry of the TFMs. General characteristics, such as cogging torque, rated torque and torque ripple characteristics of the two TFMs are analyzed and compared by extensive 3D FEA.

Investigation on the electromagnetic centring technique in compressor with labyrinth seal structure

NASA Astrophysics Data System (ADS)

Zhang, W.; Feng, C.; Cheng, J.; Feng, Q.; Wu, W.

2017-08-01

At present, the piston of compressors with labyrinth seal structure generally runs eccentrically, which causes uneven radial clearance, serious leakages and lower volumetric efficiency. This has become an urgent problem in the development of labyrinth compressors. In this study, electromagnetic levitation technology was introduced to achieve concentric centering between the piston and cylinder, and the conventional cantilever structure for the piston centering was replaced by a simple support structure using the through-piston rod. Furthermore, the simulation model of the electromagnetic centering system was established and the experimental prototype was built. The mathematical simulation model was verified by comparing simulated and tested results. Then, the centering effect of the system was assessed and the variation of the leakage in the compressor was studied by models using dynamic mesh technology. The results showed that the radial clearance between piston and cylinder can be maintained in the range of -0.3 mm to 0.3 mm through the electromagnetic centering control. In addition, the inner leakage of the compressor was quite appreciable without the electromagnetic control. However, it was reduced by 1.8 times with the introduction of the electromagnetic control. Thus, it can be concluded that the precise centering between the piston and the cylinder can be achieved by the introduction of the electromagnetic centering technique.

Intercode comparison of gyrokinetic global electromagnetic modes

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

Görler, T., E-mail: tobias.goerler@ipp.mpg.de; Tronko, N.; Hornsby, W. A.

Aiming to fill a corresponding lack of sophisticated test cases for global electromagnetic gyrokinetic codes, a new hierarchical benchmark is proposed. Starting from established test sets with adiabatic electrons, fully gyrokinetic electrons, and electrostatic fluctuations are taken into account before finally studying the global electromagnetic micro-instabilities. Results from up to five codes involving representatives from different numerical approaches as particle-in-cell methods, Eulerian and Semi-Lagrangian are shown. By means of spectrally resolved growth rates and frequencies and mode structure comparisons, agreement can be confirmed on ion-gyro-radius scales, thus providing confidence in the correct implementation of the underlying equations.

Electromagnetic miniactuators using thin magnetic layers

NASA Astrophysics Data System (ADS)

Kube, H.; Zoeppig, V.; Hermann, R.; Hoffmann, A.; Kallenbach, E.

2000-06-01

This paper presents two examples of miniactuators based on the electromagnetic and electrodynamic force generation principle respectively. They use modern high-energy polymer-bonded permanent magnetic layers basing on NdFeB. The first example is a linear drive with an integrated magnetic bearing. It generates electrodynamic forces to lift and move a lightweight platen. The position of the platen is measured and controlled. The second example is a miniature pneumatic valve with a fully integrated polarized electromagnetic actuator. The valve consumes power only when the armature position is changed. The holding force is generated without consumption of power.

Comparisons of 'Identical' Simulations by the Eulerian Gyrokinetic Codes GS2 and GYRO

NASA Astrophysics Data System (ADS)

Bravenec, R. V.; Ross, D. W.; Candy, J.; Dorland, W.; McKee, G. R.

2003-10-01

A major goal of the fusion program is to be able to predict tokamak transport from first-principles theory. To this end, the Eulerian gyrokinetic code GS2 was developed years ago and continues to be improved [1]. Recently, the Eulerian code GYRO was developed [2]. These codes are not subject to the statistical noise inherent to particle-in-cell (PIC) codes, and have been very successful in treating electromagnetic fluctuations. GS2 is fully spectral in the radial coordinate while GYRO uses finite-differences and ``banded" spectral schemes. To gain confidence in nonlinear simulations of experiment with these codes, ``apples-to-apples" comparisons (identical profile inputs, flux-tube geometry, two species, etc.) are first performed. We report on a series of linear and nonlinear comparisons (with overall agreement) including kinetic electrons, collisions, and shaped flux surfaces. We also compare nonlinear simulations of a DIII-D discharge to measurements of not only the fluxes but also the turbulence parameters. [1] F. Jenko, et al., Phys. Plasmas 7, 1904 (2000) and refs. therein. [2] J. Candy, J. Comput. Phys. 186, 545 (2003).

A Review of High-Order and Optimized Finite-Difference Methods for Simulating Linear Wave Phenomena

NASA Technical Reports Server (NTRS)

Zingg, David W.

1996-01-01

This paper presents a review of high-order and optimized finite-difference methods for numerically simulating the propagation and scattering of linear waves, such as electromagnetic, acoustic, or elastic waves. The spatial operators reviewed include compact schemes, non-compact schemes, schemes on staggered grids, and schemes which are optimized to produce specific characteristics. The time-marching methods discussed include Runge-Kutta methods, Adams-Bashforth methods, and the leapfrog method. In addition, the following fourth-order fully-discrete finite-difference methods are considered: a one-step implicit scheme with a three-point spatial stencil, a one-step explicit scheme with a five-point spatial stencil, and a two-step explicit scheme with a five-point spatial stencil. For each method studied, the number of grid points per wavelength required for accurate simulation of wave propagation over large distances is presented. Recommendations are made with respect to the suitability of the methods for specific problems and practical aspects of their use, such as appropriate Courant numbers and grid densities. Avenues for future research are suggested.

TEMPS (Transportable EMP Simulator) Final Report. Volume 2. Appendixes

DTIC Science & Technology

1973-08-01

Electromagnetic pulse Pulser system Pulse generator 20. ASSTRPACT (Confirma an reverse ese It neessary and IdmntSIy by Weeck pmbff) This report...Research Institute I>, PIFR-372 A.1 INTRODUCTION The Transportable Electromagnetic Pulse Simulator (TEMPS) was built for the Harry Diamond Laboratories

Particle simulation of electromagnetic emissions from electrostatic instability driven by an electron ring beam on the density gradient

NASA Astrophysics Data System (ADS)

Horký, Miroslav; Omura, Yoshiharu; Santolík, Ondřej

2018-04-01

This paper presents the wave mode conversion between electrostatic and electromagnetic waves on the plasma density gradient. We use 2-D electromagnetic code KEMPO2 implemented with the generation of density gradient to simulate such a conversion process. In the dense region, we use ring beam instability to generate electron Bernstein waves and we study the temporal evolution of wave spectra, velocity distributions, Poynting flux, and electric and magnetic energies to observe the wave mode conversion. Such a conversion process can be a source of electromagnetic emissions which are routinely measured by spacecraft on the plasmapause density gradient.

Research on Radiation Characteristic of Plasma Antenna through FDTD Method

PubMed Central

Zhou, Jianming; Fang, Jingjing; Lu, Qiuyuan; Liu, Fan

2014-01-01

The radiation characteristic of plasma antenna is investigated by using the finite-difference time-domain (FDTD) approach in this paper. Through using FDTD method, we study the propagation of electromagnetic wave in free space in stretched coordinate. And the iterative equations of Maxwell equation are derived. In order to validate the correctness of this method, we simulate the process of electromagnetic wave propagating in free space. Results show that electromagnetic wave spreads out around the signal source and can be absorbed by the perfectly matched layer (PML). Otherwise, we study the propagation of electromagnetic wave in plasma by using the Boltzmann-Maxwell theory. In order to verify this theory, the whole process of electromagnetic wave propagating in plasma under one-dimension case is simulated. Results show that Boltzmann-Maxwell theory can be used to explain the phenomenon of electromagnetic wave propagating in plasma. Finally, the two-dimensional simulation model of plasma antenna is established under the cylindrical coordinate. And the near-field and far-field radiation pattern of plasma antenna are obtained. The experiments show that the variation of electron density can introduce the change of radiation characteristic. PMID:25114961

The difference of detecting water mist and smoke by electromagnetic wave in simulation experiments

NASA Astrophysics Data System (ADS)

Zhang, Jingdi; Cui, Bing; Xiao, Si

2015-10-01

Although mist is similar to smoke in morphology, their compositions are very different. Therefore there is a significant difference between mist and smoke when detected by electromagnetic wave. This paper puts forward a kind of feasible solution based on Ansoft HFSS software about how to determine the forest fire by distinguishing mist and smoke above the forest. The experiments simulate the difference between mist and smoke model when detected by electromagnetic wave in different wavelengths. We find the mist and smoke model cannot absorb or reflect electromagnetic wave efficiently in Megahertz band. While in Gigahertz band mist model began to absorb and reflect electromagnetic wave above 650 Gigahertz band, but no change in smoke model. And the biggest difference appears in Terahertz band.

Numerical simulation of the early-time high altitude electromagnetic pulse

NASA Astrophysics Data System (ADS)

Meng, Cui; Chen, Yu-Sheng; Liu, Shun-Kun; Xie, Qin-Chuan; Chen, Xiang-Yue; Gong, Jian-Cheng

2003-12-01

In this paper, the finite difference method is used to develop the Fortran software MCHII. The physical process in which the electromagnetic signal is generated by the interaction of nuclear-explosion-induced Compton currents with the geomagnetic field is numerically simulated. The electromagnetic pulse waveforms below the burst point are investigated. The effects of the height of burst, yield and the time-dependence of gamma-rays are calculated by using the MCHII code. The results agree well with those obtained by using the code CHAP.

Alternative modeling methods for plasma-based Rf ion sources

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

Veitzer, Seth A., E-mail: veitzer@txcorp.com; Kundrapu, Madhusudhan, E-mail: madhusnk@txcorp.com; Stoltz, Peter H., E-mail: phstoltz@txcorp.com

Rf-driven ion sources for accelerators and many industrial applications benefit from detailed numerical modeling and simulation of plasma characteristics. For instance, modeling of the Spallation Neutron Source (SNS) internal antenna H{sup −} source has indicated that a large plasma velocity is induced near bends in the antenna where structural failures are often observed. This could lead to improved designs and ion source performance based on simulation and modeling. However, there are significant separations of time and spatial scales inherent to Rf-driven plasma ion sources, which makes it difficult to model ion sources with explicit, kinetic Particle-In-Cell (PIC) simulation codes. Inmore » particular, if both electron and ion motions are to be explicitly modeled, then the simulation time step must be very small, and total simulation times must be large enough to capture the evolution of the plasma ions, as well as extending over many Rf periods. Additional physics processes such as plasma chemistry and surface effects such as secondary electron emission increase the computational requirements in such a way that even fully parallel explicit PIC models cannot be used. One alternative method is to develop fluid-based codes coupled with electromagnetics in order to model ion sources. Time-domain fluid models can simulate plasma evolution, plasma chemistry, and surface physics models with reasonable computational resources by not explicitly resolving electron motions, which thereby leads to an increase in the time step. This is achieved by solving fluid motions coupled with electromagnetics using reduced-physics models, such as single-temperature magnetohydrodynamics (MHD), extended, gas dynamic, and Hall MHD, and two-fluid MHD models. We show recent results on modeling the internal antenna H{sup −} ion source for the SNS at Oak Ridge National Laboratory using the fluid plasma modeling code USim. We compare demonstrate plasma temperature equilibration in two-temperature MHD models for the SNS source and present simulation results demonstrating plasma evolution over many Rf periods for different plasma temperatures. We perform the calculations in parallel, on unstructured meshes, using finite-volume solvers in order to obtain results in reasonable time.« less

Alternative modeling methods for plasma-based Rf ion sources.

PubMed

Veitzer, Seth A; Kundrapu, Madhusudhan; Stoltz, Peter H; Beckwith, Kristian R C

2016-02-01

Rf-driven ion sources for accelerators and many industrial applications benefit from detailed numerical modeling and simulation of plasma characteristics. For instance, modeling of the Spallation Neutron Source (SNS) internal antenna H(-) source has indicated that a large plasma velocity is induced near bends in the antenna where structural failures are often observed. This could lead to improved designs and ion source performance based on simulation and modeling. However, there are significant separations of time and spatial scales inherent to Rf-driven plasma ion sources, which makes it difficult to model ion sources with explicit, kinetic Particle-In-Cell (PIC) simulation codes. In particular, if both electron and ion motions are to be explicitly modeled, then the simulation time step must be very small, and total simulation times must be large enough to capture the evolution of the plasma ions, as well as extending over many Rf periods. Additional physics processes such as plasma chemistry and surface effects such as secondary electron emission increase the computational requirements in such a way that even fully parallel explicit PIC models cannot be used. One alternative method is to develop fluid-based codes coupled with electromagnetics in order to model ion sources. Time-domain fluid models can simulate plasma evolution, plasma chemistry, and surface physics models with reasonable computational resources by not explicitly resolving electron motions, which thereby leads to an increase in the time step. This is achieved by solving fluid motions coupled with electromagnetics using reduced-physics models, such as single-temperature magnetohydrodynamics (MHD), extended, gas dynamic, and Hall MHD, and two-fluid MHD models. We show recent results on modeling the internal antenna H(-) ion source for the SNS at Oak Ridge National Laboratory using the fluid plasma modeling code USim. We compare demonstrate plasma temperature equilibration in two-temperature MHD models for the SNS source and present simulation results demonstrating plasma evolution over many Rf periods for different plasma temperatures. We perform the calculations in parallel, on unstructured meshes, using finite-volume solvers in order to obtain results in reasonable time.

Covariant electromagnetic field lines

NASA Astrophysics Data System (ADS)

Hadad, Y.; Cohen, E.; Kaminer, I.; Elitzur, A. C.

2017-08-01

Faraday introduced electric field lines as a powerful tool for understanding the electric force, and these field lines are still used today in classrooms and textbooks teaching the basics of electromagnetism within the electrostatic limit. However, despite attempts at generalizing this concept beyond the electrostatic limit, such a fully relativistic field line theory still appears to be missing. In this work, we propose such a theory and define covariant electromagnetic field lines that naturally extend electric field lines to relativistic systems and general electromagnetic fields. We derive a closed-form formula for the field lines curvature in the vicinity of a charge, and show that it is related to the world line of the charge. This demonstrates how the kinematics of a charge can be derived from the geometry of the electromagnetic field lines. Such a theory may also provide new tools in modeling and analyzing electromagnetic phenomena, and may entail new insights regarding long-standing problems such as radiation-reaction and self-force. In particular, the electromagnetic field lines curvature has the attractive property of being non-singular everywhere, thus eliminating all self-field singularities without using renormalization techniques.

Field-Based Optimal Placement of Antennas for Body-Worn Wireless Sensors

PubMed Central

Januszkiewicz, Łukasz; Di Barba, Paolo; Hausman, Sławomir

2016-01-01

We investigate a case of automated energy-budget-aware optimization of the physical position of nodes (sensors) in a Wireless Body Area Network (WBAN). This problem has not been presented in the literature yet, as opposed to antenna and routing optimization, which are relatively well-addressed. In our research, which was inspired by a safety-critical application for firefighters, the sensor network consists of three nodes located on the human body. The nodes communicate over a radio link operating in the 2.4 GHz or 5.8 GHz ISM frequency band. Two sensors have a fixed location: one on the head (earlobe pulse oximetry) and one on the arm (with accelerometers, temperature and humidity sensors, and a GPS receiver), while the position of the third sensor can be adjusted within a predefined region on the wearer’s chest. The path loss between each node pair strongly depends on the location of the nodes and is difficult to predict without performing a full-wave electromagnetic simulation. Our optimization scheme employs evolutionary computing. The novelty of our approach lies not only in the formulation of the problem but also in linking a fully automated optimization procedure with an electromagnetic simulator and a simplified human body model. This combination turns out to be a computationally effective solution, which, depending on the initial placement, has a potential to improve performance of our example sensor network setup by up to about 20 dB with respect to the path loss between selected nodes. PMID:27196911

Research on modeling and conduction disturbance simulation of secondary power system in a device

NASA Astrophysics Data System (ADS)

Ding, Xu; Yu, Zhi-Yong; Jin, Rui

2017-06-01

To find electromagnetic interference (EMI) and other problems in the secondary power supply system design quickly and effectively, simulations are carried out under the Saber simulation software platform. The DC/DC converter model with complete performance and electromagnetic characteristics is established by combining parametric modeling with Mast language. By using the method of macro modeling, the hall current sensor and power supply filter model are established respectively based on the function, schematic diagram of the components. Also the simulation of the component model and the whole secondary power supply system are carried out. The simulation results show that the proposed model satisfies the functional requirements of the system and has high accuracy. At the same time, due to the ripple characteristics in the DC/DC converter modeling, it can be used as a conducted interference model to simulate the power bus conducted emission CE102 project under the condition that the simulated load is full, which provides a useful reference for the electromagnetic interference suppression of the system.

Small Portable Analyzer Diagnostic Equipment (SPADE) Program -- Diagnostic Software Validation

DTIC Science & Technology

1984-07-01

Electronic Equipment Electromagnetic Emission and Susceptibility Requirements for the Control of Electromagnetic Interference Electromagnetic...ONLY. ORIENTATION OF DEFECT LOOKING HHO QIlILL: t -ed’-o· Significant efforts were expended to simulate spalling failures associated with naturally

Modification of Turbulence Structures in a Channel Flow by Uniform Magnetic Fluxes

NASA Astrophysics Data System (ADS)

Lee, D.; Choi, H.; Kim, J.

1997-11-01

Effects of electromagnetic forcing on the near-wall turbulence are investigated by applying a uniform magnetic flux in a turbulent channel flow in the streamwise and spanwise directions, respectively. The base flow is a fully developed turbulent channel flow and the direct numerical simulation technique is used. The electromagnetic force induced from the magnetic fluxes reduces the intensity of the wall-layer structures and thus drag is significantly reduced. The wall-normal and spanwise velocity fluctuations and the Reynolds shear stress decrease with the increased magnetic flux in both directions. The streamwise velocity fluctuations increase with the streamwise magnetic flux, whereas they decrease with the spanwise magnetic flux. It is also shown that the spanwise magnetic flux is much more effective than the streamwise magnetic flux in reducing the skin-friction drag. Instantaneous Lorentz force vectors show that the flow motions by the near-wall vortices are directly inhibited by the spanwise magnetic flux, while they are less effectively inhibited by the streamwise magnetic flux. Other turbulence statistics that reveal the effects of the applied magnetic forcing will be presented. ^* Supported by KOSEF Contract No. 965-1008-003-2 and ONR Grant No. N00014-95-1-0352.

Finite Element Modeling of Magnetically-Damped Convection during Solidification

NASA Technical Reports Server (NTRS)

deGroh, H. C.; Li, B. Q.; Lu, X.

1998-01-01

A fully 3-D, transient finite element model is developed to represent the magnetic damping effects on complex fluid flow, heat transfer and electromagnetic field distributions in a Sn- 35.5%Pb melt undergoing unidirectional solidification. The model is developed based on our in- house finite element code for the fluid flow, heat transfer and electromagnetic field calculations. The numerical model is tested against numerical and experimental results for water as reported in literature. Various numerical simulations are carried out for the melt convection and temperature distribution with and without the presence of a transverse magnetic field. Numerical results show that magnetic damping can be effectively applied to stabilize melt flow, reduce turbulence and flow levels in the melt and over a certain threshold value a higher magnetic field resulted in a greater reduction in velocity. Also, for the study of melt flow instability, a long enough running time is needed to ensure the final fluid flow recirculation pattern. Moreover, numerical results suggest that there seems to exist a threshold value of applied magnetic field, above which magnetic damping becomes possible and below which the 0 convection in the melt is actually enhanced.

Large-aperture Tunable Plasma Meta-material to Interact with Electromagnetic Waves

NASA Astrophysics Data System (ADS)

Corke, Thomas; Matlis, Eric

2016-11-01

The formation of spatially periodic arrangements of glow discharge plasma resulting from charge instabilities were investigated as a tuneable plasma meta-material. The plasma was formed between two 2-D parallel dielectric covered electrodes: one consisting of an Indium-Tin-Oxide coated glass sheet, and the other consisting of a glass-covered circular electrode. The dielectric covered electrodes were separated by a gap that formed a 2-D channel. The gap spacing was adjustable. The electrodes were powered by a variable amplitude AC generator. The parallel electrode arrangement was placed in a variable pressure vacuum chamber. Various combinations of gap spacing, pressure and voltage resulted in the formation of spatially periodic arrangements (lattice) of glow discharge plasma. The lattice spacing perfectly followed 2-D packing theory, and was fully adjustable through the three governing parameters. Lattice arrangements were designed to interact with electromagnetic (EM) waves in the frequency range between 10GHz-80GHz. Its feasibility was investigate through an EM wave simulation that we adapted to allow for plasma permittivity. The results showed a clear suppression of the EM wave amplitude through the plasma gratings. Supported by AFOSR.

Particle-in-cell Simulation of Dipolarization Front Associated Whistlers

NASA Astrophysics Data System (ADS)

Lin, D.; Scales, W.; Ganguli, G.; Crabtree, C. E.

2017-12-01

Dipolarization fronts (DFs) are dipolarized magnetic field embedded in the Earthward propagating bursty bulk flows (BBFs), which separates the hot, tenuous high-speed flow from the cold, dense, and slowly convecting surrounding plasma [Runov et al. 2011]. Broadband fluctuations have been observed at DFs including the electromagnetic whistler waves and electrostatic lower hybrid waves in the Very Low Frequency (VLF) range [e.g., Zhou et al. 2009, Deng et al. 2010]. There waves are suggested to be able heat electrons and play a critical role in the plasma sheet dynamics [Chaston et al., 2012, Angelopoulos et al., 2013]. However, their generation mechanism and role in the energy conversion are still under debate. The gradient scale of magnetic field, plasma density at DFs in the near-Earth magnetotail is comparable to or lower than the ion gyro radius [Runov et al., 2011, Fu et al., 2012, Breuillard et al., 2016]. Such strongly inhomogeneous configuration could be unstable to the electron-ion hybrid (EIH) instability, which arises from strongly sheared transverse flow and is in the VLF range [Ganguli et al. 1988, Ganguli et al. 2014]. The equilibrium of the EIH theory implies an anisotropy of electron temperature, which are likely to drive the whistler waves observed in DFs [Deng et al., 2010, Gary et al., 2011]. In order to better understand how the whistler waves are generated in DFs and whether the EIH theory is applicable, a fully electromagnetic particle-in-cell (EMPIC) model is used to simulate the EIH instability with similar equilibrium configurations in DF observations. The EMPIC model deals with three dimensions in the velocity space and two dimensions in the configuration space, which is quite ready to include the third configuration dimension. Simulation results will be shown in this presentation.

Estimating the Contribution of Dynamical Ejecta in the Kilonova Associated with GW170817

NASA Astrophysics Data System (ADS)

Abbott, B. P.; Abbott, R.; Abbott, T. D.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Afrough, M.; Agarwal, B.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allen, G.; Allocca, A.; Altin, P. A.; Amato, A.; Ananyeva, A.; Anderson, S. B.; Anderson, W. G.; Angelova, S. V.; Antier, S.; Appert, S.; Arai, K.; Araya, M. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Atallah, D. V.; Aufmuth, P.; Aulbert, C.; AultONeal, K.; Austin, C.; Avila-Alvarez, A.; Babak, S.; Bacon, P.; Bader, M. K. M.; Bae, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Banagiri, S.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barkett, K.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bawaj, M.; Bayley, J. C.; Bazzan, M.; Bécsy, B.; Beer, C.; Bejger, M.; Belahcene, I.; Bell, A. S.; Bergmann, G.; Bernuzzi, S.; Bero, J. J.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Billman, C. R.; Birch, J.; Birney, R.; Birnholtz, O.; Biscans, S.; Biscoveanu, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackman, J.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bode, N.; Boer, M.; Bogaert, G.; Bohe, A.; Bondu, F.; Bonilla, E.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bossie, K.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Broida, J. E.; Brooks, A. F.; Brown, D. D.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T. A.; Calloni, E.; Camp, J. B.; Canepa, M.; Canizares, P.; Cannon, K. C.; Cao, H.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Carney, M. F.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerdá-Durán, P.; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chase, E.; Chassande-Mottin, E.; Chatterjee, D.; Chatziioannou, K.; Cheeseboro, B. D.; Chen, H. Y.; Chen, X.; Chen, Y.; Cheng, H.-P.; Chia, H.; Chincarini, A.; Chiummo, A.; Chmiel, T.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, A. J. K.; Chua, S.; Chung, A. K. W.; Chung, S.; Ciani, G.; Ciolfi, R.; Cirelli, C. E.; Cirone, A.; Clara, F.; Clark, J. A.; Clearwater, P.; Cleva, F.; Cocchieri, C.; Coccia, E.; Cohadon, P.-F.; Cohen, D.; Colla, A.; Collette, C. G.; Cominsky, L. R.; Constancio, M., Jr.; Conti, L.; Cooper, S. J.; Corban, P.; Corbitt, T. R.; Cordero-Carrión, I.; Corley, K. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Covas, P. B.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cullen, T. J.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Dálya, G.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dasgupta, A.; Da Silva Costa, C. F.; Dattilo, V.; Dave, I.; Davier, M.; Davis, D.; Daw, E. J.; Day, B.; De, S.; DeBra, D.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Demos, N.; Denker, T.; Dent, T.; De Pietri, R.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; De Rossi, C.; DeSalvo, R.; de Varona, O.; Devenson, J.; Dhurandhar, S.; Díaz, M. C.; Dietrich, T.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Renzo, F.; Doctor, Z.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorrington, I.; Douglas, R.; Dovale Álvarez, M.; Downes, T. P.; Drago, M.; Dreissigacker, C.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dupej, P.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Eisenstein, R. A.; Essick, R. C.; Estevez, D.; Etienne, Z. B.; Etzel, T.; Evans, M.; Evans, T. M.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Farinon, S.; Farr, B.; Farr, W. M.; Fauchon-Jones, E. J.; Favata, M.; Fays, M.; Fee, C.; Fehrmann, H.; Feicht, J.; Fejer, M. M.; Fernandez-Galiana, A.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Finstad, D.; Fiori, I.; Fiorucci, D.; Fishbach, M.; Fisher, R. P.; Fitz-Axen, M.; Flaminio, R.; Fletcher, M.; Fong, H.; Font, J. A.; Forsyth, P. W. F.; Forsyth, S. S.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fries, E. M.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H.; Gadre, B. U.; Gaebel, S. M.; Gair, J. R.; Gammaitoni, L.; Ganija, M. R.; Gaonkar, S. G.; Garcia-Quiros, C.; Garufi, F.; Gateley, B.; Gaudio, S.; Gaur, G.; Gayathri, V.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, D.; George, J.; Gergely, L.; Germain, V.; Ghonge, S.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glover, L.; Goetz, E.; Goetz, R.; Gomes, S.; Goncharov, B.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Gretarsson, E. M.; Groot, P.; Grote, H.; Grunewald, S.; Gruning, P.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Halim, O.; Hall, B. R.; Hall, E. D.; Hamilton, E. Z.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hannuksela, O. A.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Haster, C.-J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hinderer, T.; Hoak, D.; Hofman, D.; Holt, K.; Holz, D. E.; Hopkins, P.; Horst, C.; Hough, J.; Houston, E. A.; Howell, E. J.; Hreibi, A.; Hu, Y. M.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Inta, R.; Intini, G.; Isa, H. N.; Isac, J.-M.; Isi, M.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Johnson-McDaniel, N. K.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Junker, J.; Kalaghatgi, C. V.; Kalogera, V.; Kamai, B.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kapadia, S. J.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Kastaun, W.; Katolik, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kawabe, K.; Kawaguchi, K.; Kéfélian, F.; Keitel, D.; Kemball, A. J.; Kennedy, R.; Kent, C.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J. C.; Kim, K.; Kim, W.; Kim, W. S.; Kim, Y.-M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kinley-Hanlon, M.; Kirchhoff, R.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Knowles, T. D.; Koch, P.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Krämer, C.; Kringel, V.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kumar, S.; Kuo, L.; Kutynia, A.; Kwang, S.; Lackey, B. D.; Lai, K. H.; Landry, M.; Lang, R. N.; Lange, J.; Lantz, B.; Lanza, R. K.; Larson, S. L.; Lartaux-Vollard, A.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, H. W.; Lee, K.; Lehmann, J.; Lenon, A.; Leonardi, M.; Leroy, N.; Letendre, N.; Levin, Y.; Li, T. G. F.; Linker, S. D.; Littenberg, T. B.; Liu, J.; Liu, X.; Lo, R. K. L.; Lockerbie, N. A.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lousto, C. O.; Lovelace, G.; Lück, H.; Lumaca, D.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macas, R.; Macfoy, S.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña Hernandez, I.; Magaña-Sandoval, F.; Magaña Zertuche, L.; Magee, R. M.; Majorana, E.; Maksimovic, I.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markakis, C.; Markosyan, A. S.; Markowitz, A.; Maros, E.; Marquina, A.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Mason, K.; Massera, E.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matas, A.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McCuller, L.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McNeill, L.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Mehmet, M.; Meidam, J.; Mejuto-Villa, E.; Melatos, A.; Mendell, G.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, B. B.; Miller, J.; Millhouse, M.; Milovich-Goff, M. C.; Minazzoli, O.; Minenkov, Y.; Ming, J.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moffa, D.; Moggi, A.; Mogushi, K.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Muñiz, E. A.; Muratore, M.; Murray, P. G.; Napier, K.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Neilson, J.; Nelemans, G.; Nelson, T. J. N.; Nery, M.; Neunzert, A.; Nevin, L.; Newport, J. M.; Newton, G.; Ng, K. K. Y.; Nguyen, T. T.; Nichols, D.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Noack, A.; Nocera, F.; Nolting, D.; North, C.; Nuttall, L. K.; Oberling, J.; O'Dea, G. D.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Okada, M. A.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; Ormiston, R.; Ortega, L. F.; O'Shaughnessy, R.; Ossokine, S.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pace, A. E.; Page, J.; Page, M. A.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, Howard; Pan, Huang-Wei; Pang, B.; Pang, P. T. H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Parida, A.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patil, M.; Patricelli, B.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perez, C. J.; Perreca, A.; Perri, L. M.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pirello, M.; Pitkin, M.; Poe, M.; Poggiani, R.; Popolizio, P.; Porter, E. K.; Post, A.; Powell, J.; Prasad, J.; Pratt, J. W. W.; Pratten, G.; Predoi, V.; Prestegard, T.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rajbhandari, B.; Rakhmanov, M.; Ramirez, K. E.; Ramos-Buades, A.; Rapagnani, P.; Raymond, V.; Razzano, M.; Read, J.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Ren, W.; Reyes, S. D.; Ricci, F.; Ricker, P. M.; Rieger, S.; Riles, K.; Rizzo, M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, R.; Romel, C. L.; Romie, J. H.; Rosińska, D.; Ross, M. P.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Rutins, G.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sampson, L. M.; Sanchez, E. J.; Sanchez, L. E.; Sanchis-Gual, N.; Sandberg, V.; Sanders, J. R.; Sassolas, B.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Scheel, M.; Scheuer, J.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schulte, B. W.; Schutz, B. F.; Schwalbe, S. G.; Scott, J.; Scott, S. M.; Seidel, E.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Shaddock, D. A.; Shaffer, T. J.; Shah, A. A.; Shahriar, M. S.; Shaner, M. B.; Shao, L.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Singer, L. P.; Singh, A.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, B.; Smith, J. R.; Smith, R. J. E.; Somala, S.; Son, E. J.; Sonnenberg, J. A.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Spencer, A. P.; Srivastava, A. K.; Staats, K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stevenson, S. P.; Stone, R.; Stops, D. J.; Strain, K. A.; Stratta, G.; Strigin, S. E.; Strunk, A.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Suresh, J.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Tait, S. C.; Talbot, C.; Talukder, D.; Tanner, D. B.; Tápai, M.; Taracchini, A.; Tasson, J. D.; Taylor, J. A.; Taylor, R.; Tewari, S. V.; Theeg, T.; Thies, F.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tonelli, M.; Tornasi, Z.; Torres-Forné, A.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trinastic, J.; Tringali, M. C.; Trozzo, L.; Tsang, K. W.; Tse, M.; Tso, R.; Tsukada, L.; Tsuna, D.; Tuyenbayev, D.; Ueno, K.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Varma, V.; Vass, S.; Vasúth, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Venugopalan, G.; Verkindt, D.; Vetrano, F.; Viceré, A.; Viets, A. D.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walet, R.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, J. Z.; Wang, W. H.; Wang, Y. F.; Ward, R. L.; Warner, J.; Was, M.; Watchi, J.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wessel, E. K.; Weßels, P.; Westerweck, J.; Westphal, T.; Wette, K.; Whelan, J. T.; Whiting, B. F.; Whittle, C.; Wilken, D.; Williams, D.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Wofford, J.; Wong, K. W. K.; Worden, J.; Wright, J. L.; Wu, D. S.; Wysocki, D. M.; Xiao, S.; Yamamoto, H.; Yancey, C. C.; Yang, L.; Yap, M. J.; Yazback, M.; Yu, Hang; Yu, Haocun; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zelenova, T.; Zendri, J.-P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, T.; Zhang, Y.-H.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, S. J.; Zhu, X. J.; Zimmerman, A. B.; Zucker, M. E.; Zweizig, J.; (LIGO Scientific Collaboration; Virgo Collaboration

2017-12-01

The source of the gravitational-wave (GW) signal GW170817, very likely a binary neutron star merger, was also observed electromagnetically, providing the first multi-messenger observations of this type. The two-week-long electromagnetic (EM) counterpart had a signature indicative of an r-process-induced optical transient known as a kilonova. This Letter examines how the mass of the dynamical ejecta can be estimated without a direct electromagnetic observation of the kilonova, using GW measurements and a phenomenological model calibrated to numerical simulations of mergers with dynamical ejecta. Specifically, we apply the model to the binary masses inferred from the GW measurements, and use the resulting mass of the dynamical ejecta to estimate its contribution (without the effects of wind ejecta) to the corresponding kilonova light curves from various models. The distributions of dynamical ejecta mass range between {M}{ej}={10}-3-{10}-2 {M}⊙ for various equations of state, assuming that the neutron stars are rotating slowly. In addition, we use our estimates of the dynamical ejecta mass and the neutron star merger rates inferred from GW170817 to constrain the contribution of events like this to the r-process element abundance in the Galaxy when ejecta mass from post-merger winds is neglected. We find that if ≳10% of the matter dynamically ejected from binary neutron star (BNS) mergers is converted to r-process elements, GW170817-like BNS mergers could fully account for the amount of r-process material observed in the Milky Way.

Measurement of the transient shielding effectiveness of shielding cabinets

NASA Astrophysics Data System (ADS)

Herlemann, H.; Koch, M.

2008-05-01

Recently, new definitions of shielding effectiveness (SE) for high-frequency and transient electromagnetic fields were introduced by Klinkenbusch (2005). Analytical results were shown for closed as well as for non closed cylindrical shields. In the present work, the shielding performance of different shielding cabinets is investigated by means of numerical simulations and measurements inside a fully anechoic chamber and a GTEM-cell. For the GTEM-cell-measurements, a downscaled model of the shielding cabinet is used. For the simulations, the numerical tools CONCEPT II and COMSOL MULTIPHYSICS were available. The numerical results agree well with the measurements. They can be used to interpret the behaviour of the shielding effectiveness of enclosures as function of frequency. From the measurement of the electric and magnetic fields with and without the enclosure in place, the electric and magnetic shielding effectiveness as well as the transient shielding effectiveness of the enclosure are calculated. The transient SE of four different shielding cabinets is determined and discussed.

Numerical simulation of hull curved plate forming by electromagnetic force assisted line heating

NASA Astrophysics Data System (ADS)

Wang, Ji; Wang, Shun; Liu, Yujun; Li, Rui; Liu, xiao

2017-11-01

Line heating is a common method in shipyards for forming of hull curved plate. The aluminum alloy plate is widely used in shipbuilding. To solve the problem of thick aluminum alloy plate forming with complex curved surface, a new technology named electromagnetic force assisted line heating(EFALH) was proposed in this paper. The FEM model of EFALH was established and the effect of electromagnetic force assisted forming was verified by self development equipment. Firstly, the solving idea of numerical simulation for EFALH was illustrated. Then, the coupled numerical simulation model of multi physical fields were established. Lastly, the reliability of the numerical simulation model was verified by comparing the experimental data. This paper lays a foundation for solving the forming problems of thick aluminum alloy curved plate in shipbuilding.

A FLUKA simulation of the KLOE electromagnetic calorimeter

NASA Astrophysics Data System (ADS)

Di Micco, B.; Branchini, P.; Ferrari, A.; Loffredo, S.; Passeri, A.; Patera, V.

2007-10-01

We present the simulation of the KLOE calorimeter with the FLUKA Monte Carlo program. The response of the detector to electromagnetic showers has been studied and compared with the publicly available KLOE data. The energy and the time resolution of the electromagnetic clusters is in good agreement with the data. The simulation has been also used to study a possible improvement of the KLOE calorimeter using multianode photo-multipliers. An HAMAMATSU R7600-M16 photomultiplier has been assembled in order to determine the whole cross talk matrix that has been included in the simulation. The cross talk matrix takes into account the effects of a realistic photo-multiplier's electronics and of its coupling to the active material. The performance of the modified readout has been compared to the usual KLOE configuration.

Microscale Electromagnetic Heating in Heterogeneous Energetic Materials Based on X-ray Computed Tomography

NASA Astrophysics Data System (ADS)

Kort-Kamp, W. J. M.; Cordes, N. L.; Ionita, A.; Glover, B. B.; Duque, A. L. Higginbotham; Perry, W. L.; Patterson, B. M.; Dalvit, D. A. R.; Moore, D. S.

2016-04-01

Electromagnetic stimulation of energetic materials provides a noninvasive and nondestructive tool for detecting and identifying explosives. We combine structural information based on x-ray computed tomography, experimental dielectric data, and electromagnetic full-wave simulations to study microscale electromagnetic heating of realistic three-dimensional heterogeneous explosives. We analyze the formation of electromagnetic hot spots and thermal gradients in the explosive-binder mesostructures and compare the heating rate for various binder systems.

Research on key factors and their interaction effects of electromagnetic force of high-speed solenoid valve.

PubMed

Liu, Peng; Fan, Liyun; Hayat, Qaisar; Xu, De; Ma, Xiuzhen; Song, Enzhe

2014-01-01

Analysis consisting of numerical simulations along with lab experiments of interaction effects between key parameters on the electromagnetic force based on response surface methodology (RSM) has been also proposed to optimize the design of high-speed solenoid valve (HSV) and improve its performance. Numerical simulation model of HSV has been developed in Ansoft Maxwell environment and its accuracy has been validated through lab experiments. Effect of change of core structure, coil structure, armature structure, working air gap, and drive current on the electromagnetic force of HSV has been analyzed through simulation model and influence rules of various parameters on the electromagnetic force have been established. The response surface model of the electromagnetic force has been utilized to analyze the interaction effect between major parameters. It has been concluded that six interaction factors including working air gap with armature radius, drive current with armature thickness, coil turns with side pole radius, armature thickness with its radius, armature thickness with side pole radius, and armature radius with side pole radius have significant influence on the electromagnetic force. Optimal match values between coil turns and side pole radius; armature thickness and side pole radius; and armature radius and side pole radius have also been determined.

Research on Key Factors and Their Interaction Effects of Electromagnetic Force of High-Speed Solenoid Valve

PubMed Central

Fan, Liyun; Xu, De; Ma, Xiuzhen; Song, Enzhe

2014-01-01

Analysis consisting of numerical simulations along with lab experiments of interaction effects between key parameters on the electromagnetic force based on response surface methodology (RSM) has been also proposed to optimize the design of high-speed solenoid valve (HSV) and improve its performance. Numerical simulation model of HSV has been developed in Ansoft Maxwell environment and its accuracy has been validated through lab experiments. Effect of change of core structure, coil structure, armature structure, working air gap, and drive current on the electromagnetic force of HSV has been analyzed through simulation model and influence rules of various parameters on the electromagnetic force have been established. The response surface model of the electromagnetic force has been utilized to analyze the interaction effect between major parameters. It has been concluded that six interaction factors including working air gap with armature radius, drive current with armature thickness, coil turns with side pole radius, armature thickness with its radius, armature thickness with side pole radius, and armature radius with side pole radius have significant influence on the electromagnetic force. Optimal match values between coil turns and side pole radius; armature thickness and side pole radius; and armature radius and side pole radius have also been determined. PMID:25243217

Broadband enhancement of dielectric light trapping nanostructure used in ultra-thin solar cells

NASA Astrophysics Data System (ADS)

Yang, Dong; Xu, Zhaopeng; Bian, Fei; Wang, Haiyan; Wang, Jiazhuang; Sun, Lu

2018-03-01

A dielectric fishnet nanostructure is designed to increase the light trapping capability of ultra-thin solar cells. The complex performance of ultra-thin cells such as the optical response and electrical response are fully quantified in simulation through a complete optoelectronic investigation. The results show that the optimized light trapping nanostructure can enhances the electromagnetic resonance in active layer then lead to extraordinary enhancement of both absorption and light-conversion capabilities in the solar cell. The short-circuit current density increases by 49.46% from 9.40 mA/cm2 to 14.05 mA/cm2 and light-conversion efficiency increases by 51.84% from 9.51% to 14.44% compared to the benchmark, a solar cell with an ITO-GaAs-Ag structure.

Effects of Physical Models and Simulations to Understand Daily Life Applications of Electromagnetic Induction

ERIC Educational Resources Information Center

Tural, Güner; Tarakçi, Demet

2017-01-01

Background: One of the topics students have difficulties in understanding is electromagnetic induction. Active learning methods instead of traditional learning method may be able to help facilitate students' understanding such topics more effectively. Purpose: The study investigated the effectiveness of physical models and simulations on students'…

Microscale electromagnetic heating in heterogeneous energetic materials based on x-ray computed tomography

DOE PAGES

Kort-Kamp, W. J. M.; Cordes, N. L.; Ionita, A.; ...

2016-04-01

Electromagnetic stimulation of energetic materials provides a noninvasive and nondestructive tool for detecting and identifying explosives. We combine structural information based on x-ray computed tomography, experimental dielectric data, and electromagnetic full-wave simulations to study microscale electromagnetic heating of realistic three-dimensional heterogeneous explosives. In conclusion, we analyze the formation of electromagnetic hot spots and thermal gradients in the explosive-binder mesostructures and compare the heating rate for various binder systems.

Microscale electromagnetic heating in heterogeneous energetic materials based on x-ray computed tomography

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

Kort-Kamp, W. J. M.; Cordes, N. L.; Ionita, A.

Electromagnetic stimulation of energetic materials provides a noninvasive and nondestructive tool for detecting and identifying explosives. We combine structural information based on x-ray computed tomography, experimental dielectric data, and electromagnetic full-wave simulations to study microscale electromagnetic heating of realistic three-dimensional heterogeneous explosives. In conclusion, we analyze the formation of electromagnetic hot spots and thermal gradients in the explosive-binder mesostructures and compare the heating rate for various binder systems.

Anthropogenic electromagnetic noise disrupts magnetic compass orientation in a migratory bird.

PubMed

Engels, Svenja; Schneider, Nils-Lasse; Lefeldt, Nele; Hein, Christine Maira; Zapka, Manuela; Michalik, Andreas; Elbers, Dana; Kittel, Achim; Hore, P J; Mouritsen, Henrik

2014-05-15

Electromagnetic noise is emitted everywhere humans use electronic devices. For decades, it has been hotly debated whether man-made electric and magnetic fields affect biological processes, including human health. So far, no putative effect of anthropogenic electromagnetic noise at intensities below the guidelines adopted by the World Health Organization has withstood the test of independent replication under truly blinded experimental conditions. No effect has therefore been widely accepted as scientifically proven. Here we show that migratory birds are unable to use their magnetic compass in the presence of urban electromagnetic noise. When European robins, Erithacus rubecula, were exposed to the background electromagnetic noise present in unscreened wooden huts at the University of Oldenburg campus, they could not orient using their magnetic compass. Their magnetic orientation capabilities reappeared in electrically grounded, aluminium-screened huts, which attenuated electromagnetic noise in the frequency range from 50 kHz to 5 MHz by approximately two orders of magnitude. When the grounding was removed or when broadband electromagnetic noise was deliberately generated inside the screened and grounded huts, the birds again lost their magnetic orientation capabilities. The disruptive effect of radiofrequency electromagnetic fields is not confined to a narrow frequency band and birds tested far from sources of electromagnetic noise required no screening to orient with their magnetic compass. These fully double-blinded tests document a reproducible effect of anthropogenic electromagnetic noise on the behaviour of an intact vertebrate.

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.

Field test of electromagnetic geophysical techniques for locating simulated in situ mining leach solution. Report of investigations/1994

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

Tweeton, D.R.; Hanson, J.C.; Friedel, M.J.

1994-01-01

The U.S. Bureau of Mines, the University of Arizona, Sandia National Laboratory, and Zonge Engineering and Research, Inc., conducted cooperative field tests of six electromagnetic geophysical methods to compare their effectiveness in locating a brine solution simulating in situ leach solution or a high-conductivity plume of contamination. The brine was approximately 160 meters below the surface. The test site was the University's San Xavier experimental mine near Tucson, Arizona. Geophysical surveys using surface and surface-borehole time-domain electromagnetics (TEM), surface controlled source audio-frequency magnetotellurics (CSAMT), surface-borehole frequency-domain electromagnetics (FEM), crosshole FEM and surface magnetic field ellipticity were conducted before and duringmore » brine injection.« less

Electromagnetic Launch Vehicle Fairing and Acoustic Blanket Model of Received Power Using FEKO

NASA Technical Reports Server (NTRS)

Trout, Dawn H.; Stanley, James E.; Wahid, Parveen F.

2011-01-01

Evaluating the impact of radio frequency transmission in vehicle fairings is important to electromagnetically sensitive spacecraft. This study employs the multilevel fast multipole method (MLFMM) from a commercial electromagnetic tool, FEKO, to model the fairing electromagnetic environment in the presence of an internal transmitter with improved accuracy over industry applied techniques. This fairing model includes material properties representative of acoustic blanketing commonly used in vehicles. Equivalent surface material models within FEKO were successfully applied to simulate the test case. Finally, a simplified model is presented using Nicholson Ross Weir derived blanket material properties. These properties are implemented with the coated metal option to reduce the model to one layer within the accuracy of the original three layer simulation.

Nonlinear Delta-f Simulations of Collective Effects in Intense Charged Particle Beams

NASA Astrophysics Data System (ADS)

Qin, Hong

2002-11-01

A nonlinear delta-f particle simulation method based on the Vlasov-Maxwell equations has been recently developed to study collective processes in high-intensity beams, where space-charge and magnetic self-field effects play a critical role in determining the nonlinear beam dynamics. Implemented in the Beam Equilibrium, Stability and Transport (BEST) code, the nonlinear delta-f method provides a low-noise and self-consistent tool for simulating collective interactions and nonlinear dynamics of high-intensity beams in modern and next- generation accelerators and storage rings, such as the Spallation Neutron Source, and heavy ion fusion drivers. Simulation results for the electron-proton two-stream instability in the Proton Storage Ring (PSR) experiment at Los Alamos National Laboratory agree well with experimental observations. Large-scale parallel simulations have also been carried out for the ion-electron two-stream instability in the very high-intensity heavy ion beams envisioned for heavy ion fusion applications. In both cases, the simulation results indicate that the dominant two-stream instability has a dipole-mode (hose-like) structure and can be stabilized by a modest axial momentum spread of the beam particles of less than 0.25collective processes in high-intensity beams, such as anisotropy-driven instabilities, collective eigenmode excitations for perturbations about stable beam equilibria, and the Darwin model for fully electromagnetic perturbations will also be discussed.

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

Vincenti, H.; Vay, J. -L.

Due to discretization effects and truncation to finite domains, many electromagnetic simulations present non-physical modifications of Maxwell's equations in space that may generate spurious signals affecting the overall accuracy of the result. Such modifications for instance occur when Perfectly Matched Layers (PMLs) are used at simulation domain boundaries to simulate open media. Another example is the use of arbitrary order Maxwell solver with domain decomposition technique that may under some condition involve stencil truncations at subdomain boundaries, resulting in small spurious errors that do eventually build up. In each case, a careful evaluation of the characteristics and magnitude of themore » errors resulting from these approximations, and their impact at any frequency and angle, requires detailed analytical and numerical studies. To this end, we present a general analytical approach that enables the evaluation of numerical discretization errors of fully three-dimensional arbitrary order finite-difference Maxwell solver, with arbitrary modification of the local stencil in the simulation domain. The analytical model is validated against simulations of domain decomposition technique and PMLs, when these are used with very high-order Maxwell solver, as well as in the infinite order limit of pseudo-spectral solvers. Results confirm that the new analytical approach enables exact predictions in each case. It also confirms that the domain decomposition technique can be used with very high-order Maxwell solver and a reasonably low number of guard cells with negligible effects on the whole accuracy of the simulation.« less

Effect of electromagnetic waves on human reproduction.

PubMed

Wdowiak, Artur; Mazurek, Paweł A; Wdowiak, Anita; Bojar, Iwona

2017-03-31

Electromagnetic radiation (EMR) emitting from the natural environment, as well as from the use of industrial and everyday appliances, constantly influence the human body. The effect of this type of energy on living tissues may exert various effects on their functioning, although the mechanisms conditioning this phenomenon have not been fully explained. It may be expected that the interactions between electromagnetic radiation and the living organism would depend on the amount and parameters of the transmitted energy and type of tissue exposed. Electromagnetic waves exert an influence on human reproduction by affecting the male and female reproductive systems, the developing embryo, and subsequently, the foetus. Knowledge concerning this problem is still being expanded; however, all the conditionings of human reproduction still remain unknown. The study presents the current state of knowledge concerning the problem, based on the latest scientific reports.

Development of an Implicit, Charge and Energy Conserving 2D Electromagnetic PIC Code on Advanced Architectures

NASA Astrophysics Data System (ADS)

Payne, Joshua; Taitano, William; Knoll, Dana; Liebs, Chris; Murthy, Karthik; Feltman, Nicolas; Wang, Yijie; McCarthy, Colleen; Cieren, Emanuel

2012-10-01

In order to solve problems such as the ion coalescence and slow MHD shocks fully kinetically we developed a fully implicit 2D energy and charge conserving electromagnetic PIC code, PlasmaApp2D. PlasmaApp2D differs from previous implicit PIC implementations in that it will utilize advanced architectures such as GPUs and shared memory CPU systems, with problems too large to fit into cache. PlasmaApp2D will be a hybrid CPU-GPU code developed primarily to run on the DARWIN cluster at LANL utilizing four 12-core AMD Opteron CPUs and two NVIDIA Tesla GPUs per node. MPI will be used for cross-node communication, OpenMP will be used for on-node parallelism, and CUDA will be used for the GPUs. Development progress and initial results will be presented.

Fast simulation of electromagnetic and hadronic showers in SpaCal calorimeter at the H1 experiment

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

Raičević, Nataša, E-mail: raicevic@mail.desy.de; Glazov, Alexandre

2016-03-25

The fast simulation of showers induced by electrons (positrons) in the H1 lead/scintillating-fiber calorimeter, SpaCal, based on shower library technique has been presented previously. In this paper we show the results on linearity and uniformity of the reconstructed electron/positron cluster energy in electromagnetic section of Spacal for the simulations based on shower library and GFLASH shower parametrisation. The shapes of the clusters originating from photon and hadron candidates in SpaCal are analysed and experimental distributions compared with the two simulations.

Numerical simulation of electromagnetic surface treatment

NASA Astrophysics Data System (ADS)

Sonde, Emmanuel; Chaise, Thibaut; Nelias, Daniel; Robin, Vincent

2018-01-01

Surface treatment methods, such as shot peening or laser shock peening, are generally used to introduce superficial compressive residual stresses in mechanical parts. These processes are carried out during the manufacturing steps or for the purpose of repairing. The compressive residual stresses prevent the initiation and growth of cracks and thus improve the fatigue life of mechanical components. Electromagnetic pulse peening (EMP) is an innovative process that could be used to introduce compressive residual stresses in conductive materials. It acts by generating a high transient electromagnetic field near the working surface. In this paper, the EMP process is presented and a sequentially coupled electromagnetic and mechanical model is developed for its simulation. This 2D axisymmetric model is set up with the commercial finite element software SYSWELD. After description and validation, the numerical model is used to simulate a case of introducing residual stresses of compression in a nickel-based alloy 690 thick sample, by the means of electromagnetic pulses. The results are presented in terms of effective plastic strain and residual mean stress. The influence of the process parameters, such as current intensity and frequency, on the results is analyzed. Finally, the predictability of the process is shown by several correlation studies.

A multiscale quantum mechanics/electromagnetics method for device simulations.

PubMed

Yam, ChiYung; Meng, Lingyi; Zhang, Yu; Chen, GuanHua

2015-04-07

Multiscale modeling has become a popular tool for research applying to different areas including materials science, microelectronics, biology, chemistry, etc. In this tutorial review, we describe a newly developed multiscale computational method, incorporating quantum mechanics into electronic device modeling with the electromagnetic environment included through classical electrodynamics. In the quantum mechanics/electromagnetics (QM/EM) method, the regions of the system where active electron scattering processes take place are treated quantum mechanically, while the surroundings are described by Maxwell's equations and a semiclassical drift-diffusion model. The QM model and the EM model are solved, respectively, in different regions of the system in a self-consistent manner. Potential distributions and current densities at the interface between QM and EM regions are employed as the boundary conditions for the quantum mechanical and electromagnetic simulations, respectively. The method is illustrated in the simulation of several realistic systems. In the case of junctionless field-effect transistors, transfer characteristics are obtained and a good agreement between experiments and simulations is achieved. Optical properties of a tandem photovoltaic cell are studied and the simulations demonstrate that multiple QM regions are coupled through the classical EM model. Finally, the study of a carbon nanotube-based molecular device shows the accuracy and efficiency of the QM/EM method.

Electromagnet Weight Reduction in a Magnetic Levitation System for Contactless Delivery Applications

PubMed Central

Hong, Do-Kwan; Woo, Byung-Chul; Koo, Dae-Hyun; Lee, Ki-Chang

2010-01-01

This paper presents an optimum design of a lightweight vehicle levitation electromagnet, which also provides a passive guide force in a magnetic levitation system for contactless delivery applications. The split alignment of C-shaped electromagnets about C-shaped rails has a bad effect on the lateral deviation force, therefore, no-split positioning of electromagnets is better for lateral performance. This is verified by simulations and experiments. This paper presents a statistically optimized design with a high number of the design variables to reduce the weight of the electromagnet under the constraint of normal force using response surface methodology (RSM) and the kriging interpolation method. 2D and 3D magnetostatic analysis of the electromagnet are performed using ANSYS. The most effective design variables are extracted by a Pareto chart. The most desirable set is determined and the influence of each design variable on the objective function can be obtained. The generalized reduced gradient (GRG) algorithm is adopted in the kriging model. This paper’s procedure is validated by a comparison between experimental and calculation results, which shows that the predicted performance of the electromagnet designed by RSM is in good agreement with the simulation results. PMID:22163572

Coupled multi-disciplinary composites behavior simulation

NASA Technical Reports Server (NTRS)

Singhal, Surendra N.; Murthy, Pappu L. N.; Chamis, Christos C.

1993-01-01

The capabilities of the computer code CSTEM (Coupled Structural/Thermal/Electro-Magnetic Analysis) are discussed and demonstrated. CSTEM computationally simulates the coupled response of layered multi-material composite structures subjected to simultaneous thermal, structural, vibration, acoustic, and electromagnetic loads and includes the effect of aggressive environments. The composite material behavior and structural response is determined at its various inherent scales: constituents (fiber/matrix), ply, laminate, and structural component. The thermal and mechanical properties of the constituents are considered to be nonlinearly dependent on various parameters such as temperature and moisture. The acoustic and electromagnetic properties also include dependence on vibration and electromagnetic wave frequencies, respectively. The simulation is based on a three dimensional finite element analysis in conjunction with composite mechanics and with structural tailoring codes, and with acoustic and electromagnetic analysis methods. An aircraft engine composite fan blade is selected as a typical structural component to demonstrate the CSTEM capabilities. Results of various coupled multi-disciplinary heat transfer, structural, vibration, acoustic, and electromagnetic analyses for temperature distribution, stress and displacement response, deformed shape, vibration frequencies, mode shapes, acoustic noise, and electromagnetic reflection from the fan blade are discussed for their coupled effects in hot and humid environments. Collectively, these results demonstrate the effectiveness of the CSTEM code in capturing the coupled effects on the various responses of composite structures subjected to simultaneous multiple real-life loads.

Electromagnetic effects on the light hadron spectrum

DOE PAGES

Basak, S.; Bazavov, A.; Bernard, C.; ...

2015-09-28

Calculations studying electromagnetic effects on light mesons are reported. The calculations use fully dynamical QCD, but only quenched photons, which suffices to NLO in χPT; that is, the sea quarks are electrically neutral, while the valence quarks carry charge. The non-compact formalism is used for photons. New results are obtained with lattice spacing as small as 0.045 fm and a large range of volumes. The success of chiral perturbation theory in describing these results and the implications for light quark masses are considered.

Coupled electromagnetic-thermodynamic simulations of microwave heating problems using the FDTD algorithm.

PubMed

Kopyt, Paweł; Celuch, Małgorzata

2007-01-01

A practical implementation of a hybrid simulation system capable of modeling coupled electromagnetic-thermodynamic problems typical in microwave heating is described. The paper presents two approaches to modeling such problems. Both are based on an FDTD-based commercial electromagnetic solver coupled to an external thermodynamic analysis tool required for calculations of heat diffusion. The first approach utilizes a simple FDTD-based thermal solver while in the second it is replaced by a universal commercial CFD solver. The accuracy of the two modeling systems is verified against the original experimental data as well as the measurement results available in literature.

Fully electromagnetic nonlinear gyrokinetic equations for tokamak edge turbulence

NASA Astrophysics Data System (ADS)

Hahm, T. S.; Wang, Lu; Madsen, J.

2009-02-01

An energy conserving set of the fully electromagnetic nonlinear gyrokinetic Vlasov equation and Maxwell's equations, which is applicable to both L-mode turbulence with large amplitude and H-mode turbulence in the presence of high E ×B shear has been derived. The phase-space action variational Lie perturbation method ensures the preservation of the conservation laws of the underlying Vlasov-Maxwell system. Generalized ordering takes ρi≪ρθi˜LE˜Lp≪R [here ρi is the thermal ion Larmor radius and ρθi=B /(Bθρi)], as typically observed in the tokamak H-mode edge, with LE and Lp being the radial electric field and pressure gradient lengths. k⊥ρi˜1 is assumed for generality, and the relative fluctuation amplitudes eδϕ /Ti˜δB/B are kept up to the second order. Extending the electrostatic theory in the presence of high E ×B shear [Hahm, Phys. Plasmas 3, 4658 (1996)], contributions of electromagnetic fluctuations to the particle charge density and current are explicitly evaluated via pullback transformation from the gyrocenter distribution function in the gyrokinetic Maxwell's equation.

Wireless Network Simulation in Aircraft Cabins

NASA Technical Reports Server (NTRS)

Beggs, John H.; Youssef, Mennatoallah; Vahala, Linda

2004-01-01

An electromagnetic propagation prediction tool was used to predict electromagnetic field strength inside airplane cabins. A commercial software package, Wireless Insite, was used to predict power levels inside aircraft cabins and the data was compared with previously collected experimental data. It was concluded that the software could qualitatively predict electromagnetic propagation inside the aircraft cabin environment.

Electromagnetic flat sheet forming by spiral type actuator coil

NASA Astrophysics Data System (ADS)

Akbar, S.; Aleem, M. A.; Sarwar, M. N.; Zillohu, A. U.; Awan, M. S.; Haider, A.; Ahmad, Z.; Akhtar, S.; Farooque, M.

2016-08-01

Focus of present work is to develop a setup for high strain rate electromagnetic forming of thin aluminum sheets (0.5, 1.0, 1.5 and 2.0 mm) and optimization of forming parameters. Flat spiral coil of 99.9% pure Cu strip (2.5x8.0 mm) with self-inductance 11 μH, 13 no. of turns and resultant outer diameter of 130mm has been fabricated and was coupled to a capacitor bank of energy, voltage and capacitance of 9 kJ, 900 V and 22.8 mF, respectively. To optimize the coil design, a commercially available software FEMM-4.2 was used to simulate the electromagnetic field profile generated by the coils of different pitch but same number of turns. Results of electromagnetic field intensity proposed by simulation agree in close proximity with those of theoretical as well as experimental data. The calculation of electromagnetic force and magnetic couplings between the coil and metal sheet are made. Forming parameters were optimized for different sheet thicknesses. Electromagnetic field intensity's profile plays a principal role in forming of typical shapes and patterns in sheets.

electromagnetics, eddy current, computer codes

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

Gartling, David

TORO Version 4 is designed for finite element analysis of steady, transient and time-harmonic, multi-dimensional, quasi-static problems in electromagnetics. The code allows simulation of electrostatic fields, steady current flows, magnetostatics and eddy current problems in plane or axisymmetric, two-dimensional geometries. TORO is easily coupled to heat conduction and solid mechanics codes to allow multi-physics simulations to be performed.

Bioelectromagnetic effects of EMP: Preliminary findings

NASA Astrophysics Data System (ADS)

Aldrich, T. E.; Easterly, C. E.; Gailey, P. C.; Hamilton, C. B.

1988-06-01

Facilities to simulate electromagnetic pulses (EMPs) are used to test military equipment and electrical communications devices for resistance to the effects of an EMP caused by an upper-atmospheric nuclear detonation. The rapid rise time and high field strengths (0.1 to 50 kV/m) of an EMP distinguish it from other electromagnetic phenomena. Certain types of EMP simulators also expose facility operators and members of the public to electromagnetic fields of varying intensity as do other natural sources such as the fields produced near a lightning bolt. Limited biological effects data have been collected to assess the potential EMP health hazards to humans. Evidence from the available database does not establish that EMPs represent either an occupational or a public health hazard. A critique is presented of the EMP research published to date in order to explore its limitations and similarities with related outcome experience from other electromagnetic field research. Laboratory research and multiple years of observations on workers in existing EMP manufacturing and simulation facilities suggest that there are no acute or short-term health effects. The occupational exposure guideline for EMP is 100 kV/m, which is far in excess of usual exposures with EMP simulators.

Perpendicular relativistic shocks in magnetized pair plasma

NASA Astrophysics Data System (ADS)

Plotnikov, Illya; Grassi, Anna; Grech, Mickael

2018-07-01

Perpendicular relativistic (γ0= 10) shocks in magnetized pair plasmas are investigated using two-dimensional Particle-in-Cell simulations. A systematic survey, from unmagnetized to strongly magnetized shocks, is presented accurately capturing the transition from Weibel-mediated to magnetic-reflection-shaped shocks. This transition is found to occur for upstream flow magnetizations 10-3 < σ < 10-2 at which a strong perpendicular net current is observed in the precursor, driving the so-called current-filamentation instability. The global structure of the shock and shock formation time are discussed. The magnetohydrodynamics shock jump conditions are found in good agreement with the numerical results, except for 10-4 < σ < 10-2 where a deviation up to 10 per cent is observed. The particle precursor length converges towards the Larmor radius of particles injected in the upstream magnetic field at intermediate magnetizations. For σ > 10-2, it leaves place to a purely electromagnetic precursor following from the strong emission of electromagnetic waves at the shock front. Particle acceleration is found to be efficient in weakly magnetized perpendicular shocks in agreement with previous works, and is fully suppressed for σ > 10-2. Diffusive shock acceleration is observed only in weakly magnetized shocks, while a dominant contribution of shock drift acceleration is evidenced at intermediate magnetizations. The spatial diffusion coefficients are extracted from the simulations allowing for a deeper insight into the self-consistent particle kinematics and scale with the square of the particle energy in weakly magnetized shocks. These results have implications for particle acceleration in the internal shocks of active galactic nucleus jets and in the termination shocks of pulsar wind nebulae.

Perpendicular relativistic shocks in magnetized pair plasma

NASA Astrophysics Data System (ADS)

Plotnikov, Illya; Grassi, Anna; Grech, Mickael

2018-04-01

Perpendicular relativistic (γ0 = 10) shocks in magnetized pair plasmas are investigated using two dimensional Particle-in-Cell simulations. A systematic survey, from unmagnetized to strongly magnetized shocks, is presented accurately capturing the transition from Weibel-mediated to magnetic-reflection-shaped shocks. This transition is found to occur for upstream flow magnetizations 10-3 < σ < 10-2 at which a strong perpendicular net current is observed in the precursor, driving the so-called current-filamentation instability. The global structure of the shock and shock formation time are discussed. The MHD shock jump conditions are found in good agreement with the numerical results, except for 10-4 < σ < 10-2 where a deviation up to 10% is observed. The particle precursor length converges toward the Larmor radius of particles injected in the upstream magnetic field at intermediate magnetizations. For σ > 10-2, it leaves place to a purely electromagnetic precursor following from the strong emission of electromagnetic waves at the shock front. Particle acceleration is found to be efficient in weakly magnetized perpendicular shocks in agreement with previous works, and is fully suppressed for σ > 10-2. Diffusive Shock Acceleration is observed only in weakly magnetized shocks, while a dominant contribution of Shock Drift Acceleration is evidenced at intermediate magnetizations. The spatial diffusion coefficients are extracted from the simulations allowing for a deeper insight into the self-consistent particle kinematics and scale with the square of the particle energy in weakly magnetized shocks. These results have implications for particle acceleration in the internal shocks of AGN jets and in the termination shocks of Pulsar Wind Nebulae.

Estimating the Contribution of Dynamical Ejecta in the Kilonova Associated with GW170817

DOE PAGES

Abbott, B. P.; Abbott, R.; Abbott, T. D.; ...

2017-12-01

The source of the gravitational-wave (GW) signal GW170817, very likely a binary neutron star merger, was also observed electromagnetically, providing the first multi-messenger observations of this type. The two-week-long electromagnetic (EM) counterpart had a signature indicative of an r-process-induced optical transient known as a kilonova. This Letter examines how the mass of the dynamical ejecta can be estimated without a direct electromagnetic observation of the kilonova, using GW measurements and a phenomenological model calibrated to numerical simulations of mergers with dynamical ejecta. Specifically, we apply the model to the binary masses inferred from the GW measurements, and use the resulting mass of the dynamical ejecta to estimate its contribution (without the effects of wind ejecta) to the corresponding kilonova light curves from various models. The distributions of dynamical ejecta mass range betweenmore » $${M}_{\\mathrm{ej}}={10}^{-3}-{10}^{-2}\\,{M}_{\\odot }$$ for various equations of state, assuming that the neutron stars are rotating slowly. In addition, we use our estimates of the dynamical ejecta mass and the neutron star merger rates inferred from GW170817 to constrain the contribution of events like this to the r-process element abundance in the Galaxy when ejecta mass from post-merger winds is neglected. We find that if ≳10% of the matter dynamically ejected from binary neutron star (BNS) mergers is converted to r-process elements, GW170817-like BNS mergers could fully account for the amount of r-process material observed in the Milky Way.« less

Estimating the Contribution of Dynamical Ejecta in the Kilonova Associated with GW170817

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

Abbott, B. P.; Abbott, R.; Abbott, T. D.

The source of the gravitational-wave (GW) signal GW170817, very likely a binary neutron star merger, was also observed electromagnetically, providing the first multi-messenger observations of this type. The two-week-long electromagnetic (EM) counterpart had a signature indicative of an r-process-induced optical transient known as a kilonova. This Letter examines how the mass of the dynamical ejecta can be estimated without a direct electromagnetic observation of the kilonova, using GW measurements and a phenomenological model calibrated to numerical simulations of mergers with dynamical ejecta. Specifically, we apply the model to the binary masses inferred from the GW measurements, and use the resulting mass of the dynamical ejecta to estimate its contribution (without the effects of wind ejecta) to the corresponding kilonova light curves from various models. The distributions of dynamical ejecta mass range betweenmore » $${M}_{\\mathrm{ej}}={10}^{-3}-{10}^{-2}\\,{M}_{\\odot }$$ for various equations of state, assuming that the neutron stars are rotating slowly. In addition, we use our estimates of the dynamical ejecta mass and the neutron star merger rates inferred from GW170817 to constrain the contribution of events like this to the r-process element abundance in the Galaxy when ejecta mass from post-merger winds is neglected. We find that if ≳10% of the matter dynamically ejected from binary neutron star (BNS) mergers is converted to r-process elements, GW170817-like BNS mergers could fully account for the amount of r-process material observed in the Milky Way.« less

Numerical analysis of multicomponent responses of surface-hole transient electromagnetic method

NASA Astrophysics Data System (ADS)

Meng, Qing-Xin; Hu, Xiang-Yun; Pan, He-Ping; Zhou, Feng

2017-03-01

We calculate the multicomponent responses of surface-hole transient electromagnetic method. The methods and models are unsuitable as geoelectric models of conductive surrounding rocks because they are based on regular local targets. We also propose a calculation and analysis scheme based on numerical simulations of the subsurface transient electromagnetic fields. In the modeling of the electromagnetic fields, the forward modeling simulations are performed by using the finite-difference time-domain method and the discrete image method, which combines the Gaver-Stehfest inverse Laplace transform with the Prony method to solve the initial electromagnetic fields. The precision in the iterative computations is ensured by using the transmission boundary conditions. For the response analysis, we customize geoelectric models consisting of near-borehole targets and conductive wall rocks and implement forward modeling simulations. The observed electric fields are converted into induced electromotive force responses using multicomponent observation devices. By comparing the transient electric fields and multicomponent responses under different conditions, we suggest that the multicomponent-induced electromotive force responses are related to the horizontal and vertical gradient variations of the transient electric field at different times. The characteristics of the response are determined by the varying the subsurface transient electromagnetic fields, i.e., diffusion, attenuation and distortion, under different conditions as well as the electromagnetic fields at the observation positions. The calculation and analysis scheme of the response consider the surrounding rocks and the anomalous field of the local targets. It therefore can account for the geological data better than conventional transient field response analysis of local targets.

Simulation of secondary emission calorimeter for future colliders

NASA Astrophysics Data System (ADS)

Yetkin, E. A.; Yetkin, T.; Ozok, F.; Iren, E.; Erduran, M. N.

2018-03-01

We present updated results from a simulation study of a conceptual sampling electromagnetic calorimeter based on secondary electron emission process. We implemented the secondary electron emission process in Geant4 as a user physics list and produced the energy spectrum and yield of secondary electrons. The energy resolution of the SEE calorimeter was σ/E = (41%) GeV1/2/√E and the response linearity to electromagnetic showers was to within 1.5%. The simulation results were also compared with a traditional scintillator calorimeter.

Electromagnetic Showers at High Energy

ERIC Educational Resources Information Center

Loos, J. S.; Dawson, S. L.

1978-01-01

Some of the properties of electromagnetic showers observed in an experimental study are illustrated. Experimental data and results from quantum electrodynamics are discussed. Data and theory are compared using computer simulation. (BB)

Electromagnetic energy momentum in dispersive media

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

Philbin, T. G.

2011-01-15

The standard derivations of electromagnetic energy and momentum in media take Maxwell's equations as the starting point. It is well known that for dispersive media this approach does not directly yield exact expressions for the energy and momentum densities. Although Maxwell's equations fully describe electromagnetic fields, the general approach to conserved quantities in field theory is not based on the field equations, but rather on the action. Here an action principle for macroscopic electromagnetism in dispersive, lossless media is used to derive the exact conserved energy-momentum tensor. The time-averaged energy density reduces to Brillouin's simple formula when the fields aremore » monochromatic. The time-averaged momentum density for monochromatic fields corresponds to the familiar Minkowski expression DxB, but for general fields in dispersive media the momentum density does not have the Minkowski value. The results are unaffected by the debate over momentum balance in light-matter interactions.« less

Properties of a Variable-Delay Polarization Modulator

NASA Technical Reports Server (NTRS)

Chuss, David T.; Wollack, Edward J.; Henry, Ross; Hui, Howard; Juarez, Aaron J.; Krenjy, Megan; Moseley, Harvey; Novak, Giles

2011-01-01

We investigate the polarization modulation properties of a variable-delay polarization modulator (VPM). The VPM modulates polarization via a variable separation between a polarizing grid and a parallel mirror. We find that in the limit where the wavelength is much larger than the diameter of the metal wires that comprise the grid, the phase delay derived from the geometric separation between the mirror and the grid is sufficient to characterize the device. However, outside of this range, additional parameters describing the polarizing grid geometry must be included to fully characterize the modulator response. In this paper, we report test results of a VPM at wavelengths of 350 micron and 3 mm. Electromagnetic simulations of wire grid polarizers were performed and are summarized using a simple circuit model that incorporates the loss and polarization properties of the device.

Scalable, Finite Element Analysis of Electromagnetic Scattering and Radiation

NASA Technical Reports Server (NTRS)

Cwik, T.; Lou, J.; Katz, D.

1997-01-01

In this paper a method for simulating electromagnetic fields scattered from complex objects is reviewed; namely, an unstructured finite element code that does not use traditional mesh partitioning algorithms.

Electron Heating and Acceleration in a Reconnecting Magnetotail

NASA Astrophysics Data System (ADS)

El-Alaoui, M.; Zhou, M.; Lapenta, G.; Berchem, J.; Richard, R. L.; Schriver, D.; Walker, R. J.

2017-12-01

Electron heating and acceleration in the magnetotail have been investigated intensively. A major site for this process is the reconnection region. However, where and how the electrons are accelerated in a realistic three-dimensional X-line geometry is not fully understood. In this study, we employed a three-dimensional implicit particle-in-cell (iPIC3D) simulation and large-scale kinetic (LSK) simulation to address these problems. We modeled a magnetotail reconnection event observed by THEMIS in an iPIC3D simulation with initial and boundary conditions given by a global magnetohydrodynamic (MHD) simulation of Earth's magnetosphere. The iPIC3D simulation system includes the region of fast outflow emanating from the reconnection site that drives dipolarization fronts. We found that current sheet electrons exhibit elongated (cigar-shaped) velocity distributions with a higher parallel temperature. Using LSK we then followed millions of test electrons using the electromagnetic fields from iPIC3D. We found that magnetotail reconnection can generate power law spectra around the near-Earth X-line. A significant number of electrons with energies higher than 50 keV are produced. We identified several acceleration mechanisms at different locations that were responsible for energizing these electrons: non-adiabatic cross-tail drift, betatron and Fermi acceleration. Relative contributions to the energy gain of these high energy electrons from the different mechanisms will be discussed.

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.

Research Studies on Electromagnetically Induced Transparency

DTIC Science & Technology

2010-01-20

allowing the same simple equations to be used to simulate nonlinear and quantum optics with the N-photon states generated in this regime. One...induced transparency, photon interactions with atoms, nonclassical states of the electromagnetic field, including entangled photon states , quantum ...them. This is important because optical nonlinearities when produced using electromagnetically induced transparency continue to increase in the

Computer simulation of magnetization-controlled shunt reactors for calculating electromagnetic transients in power systems

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

Karpov, A. S.

2013-01-15

A computer procedure for simulating magnetization-controlled dc shunt reactors is described, which enables the electromagnetic transients in electric power systems to be calculated. It is shown that, by taking technically simple measures in the control system, one can obtain high-speed reactors sufficient for many purposes, and dispense with the use of high-power devices for compensating higher harmonic components.

Electromagnetic Extended Finite Elements for High-Fidelity Multimaterial Problems LDRD Final Report

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

Siefert, Christopher; Bochev, Pavel Blagoveston; Kramer, Richard Michael Jack

Surface effects are critical to the accurate simulation of electromagnetics (EM) as current tends to concentrate near material surfaces. Sandia EM applications, which include exploding bridge wires for detonator design, electromagnetic launch of flyer plates for material testing and gun design, lightning blast-through for weapon safety, electromagnetic armor, and magnetic flux compression generators, all require accurate resolution of surface effects. These applications operate in a large deformation regime, where body-fitted meshes are impractical and multimaterial elements are the only feasible option. State-of-the-art methods use various mixture models to approximate the multi-physics of these elements. The empirical nature of these modelsmore » can significantly compromise the accuracy of the simulation in this very important surface region. We propose to substantially improve the predictive capability of electromagnetic simulations by removing the need for empirical mixture models at material surfaces. We do this by developing an eXtended Finite Element Method (XFEM) and an associated Conformal Decomposition Finite Element Method (CDFEM) which satisfy the physically required compatibility conditions at material interfaces. We demonstrate the effectiveness of these methods for diffusion and diffusion-like problems on node, edge and face elements in 2D and 3D. We also present preliminary work on h -hierarchical elements and remap algorithms.« less

Optoelectronic Evaluation and Loss Analysis of PEDOT:PSS/Si Hybrid Heterojunction Solar Cells.

PubMed

Yang, Zhenhai; Fang, Zebo; Sheng, Jiang; Ling, Zhaoheng; Liu, Zhaolang; Zhu, Juye; Gao, Pingqi; Ye, Jichun

2017-12-01

The organic/silicon (Si) hybrid heterojunction solar cells (HHSCs) have attracted considerable attention due to their potential advantages in high efficiency and low cost. However, as a newly arisen photovoltaic device, its current efficiency is still much worse than commercially available Si solar cells. Therefore, a comprehensive and systematical optoelectronic evaluation and loss analysis on this HHSC is therefore highly necessary to fully explore its efficiency potential. Here, a thoroughly optoelectronic simulation is provided on a typical planar polymer poly (3,4-ethylenedioxy thiophene):polystyrenesulfonate (PEDOT:PSS)/Si HHSC. The calculated spectra of reflection and external quantum efficiency (EQE) match well with the experimental results in a full-wavelength range. The losses in current density, which are contributed by both optical losses (i.e., reflection, electrode shield, and parasitic absorption) and electrical recombination (i.e., the bulk and surface recombination), are predicted via carefully addressing the electromagnetic and carrier-transport processes. In addition, the effects of Si doping concentrations and rear surface recombination velocities on the device performance are fully investigated. The results drawn in this study are beneficial to the guidance of designing high-performance PEDOT:PSS/Si HHSCs.

Nonlinear electromagnetic gyrokinetic particle simulations with the electron hybrid model

NASA Astrophysics Data System (ADS)

Nishimura, Y.; Lin, Z.; Chen, L.; Hahm, T.; Wang, W.; Lee, W.

2006-10-01

The electromagnetic model with fluid electrons is successfully implemented into the global gyrokinetic code GTC. In the ideal MHD limit, shear Alfven wave oscillation and continuum damping is demonstrated. Nonlinear electromagnetic simulation is further pursued in the presence of finite ηi. Turbulence transport in the AITG unstable β regime is studied. This work is supported by Department of Energy (DOE) Grant DE-FG02-03ER54724, Cooperative Agreement No. DE-FC02-04ER54796 (UCI), DOE Contract No. DE-AC02-76CH03073 (PPPL), and in part by SciDAC Center for Gyrokinetic Particle Simulation of Turbulent Transport in Burning Plasmas. Z. Lin, et al., Science 281, 1835 (1998). F. Zonca and L. Chen, Plasma Phys. Controlled Fusion 30, 2240 (1998); G. Zhao and L. Chen, Phys. Plasmas 9, 861 (2002).

Computer simulations of electromagnetic cool ion beam instabilities. [in near earth space

NASA Technical Reports Server (NTRS)

Gary, S. P.; Madland, C. D.; Schriver, D.; Winske, D.

1986-01-01

Electromagnetic ion beam instabilities driven by cool ion beams at propagation parallel or antiparallel to a uniform magnetic field are studied using computer simulations. The elements of linear theory applicable to electromagnetic ion beam instabilities and the simulations derived from a one-dimensional hybrid computer code are described. The quasi-linear regime of the right-hand resonant ion beam instability, and the gyrophase bunching of the nonlinear regime of the right-hand resonant and nonresonant instabilities are examined. It is detected that in the quasi-linear regime the instability saturation is due to a reduction in the beam core relative drift speed and an increase in the perpendicular-to-parallel beam temperature; in the nonlinear regime the instabilities saturate when half the initial beam drift kinetic energy density is converted to fluctuating magnetic field energy density.

Electromagnetic ion/ion cyclotron instability - Theory and simulations

NASA Technical Reports Server (NTRS)

Winske, D.; Omidi, N.

1992-01-01

Linear theory and 1D and 2D hybrid simulations are employed to study electromagnetic ion/ion cyclotron (EMIIC) instability driven by the relative streaming of two field-aligned ion beams. The characteristics of the instability are studied as a function of beam density, propagation angle, electron-ion temperature ratios, and ion beta. When the propagation angle is near 90 deg the EMIIC instability has the characteristics of an electrostatic instability, while at smaller angles electromagnetic effects play a significant role as does strong beam coupling. The 2D simulations point to a narrowing of the wave spectrum and accompanying coherent effects during the linear growth stage of development. The EMIIC instability is an important effect where ion beta is low such as in the plasma-sheet boundary layer and upstream of slow shocks in the magnetotail.

Exact analytic solutions of Maxwell's equations describing propagating nonparaxial electromagnetic beams.

PubMed

Garay-Avendaño, Roger L; Zamboni-Rached, Michel

2014-07-10

In this paper, we propose a method that is capable of describing in exact and analytic form the propagation of nonparaxial scalar and electromagnetic beams. The main features of the method presented here are its mathematical simplicity and the fast convergence in the cases of highly nonparaxial electromagnetic beams, enabling us to obtain high-precision results without the necessity of lengthy numerical simulations or other more complex analytical calculations. The method can be used in electromagnetism (optics, microwaves) as well as in acoustics.

A finite-difference time-domain electromagnetic solver in a generalized coordinate system

NASA Astrophysics Data System (ADS)

Hochberg, Timothy Allen

A new, finite-difference, time-domain method for the simulation of full-wave electromagnetic wave propogation in complex structures is developed. This method is simple and flexible; it allows for the simulation of transient wave propogation in a large class of practical structures. Boundary conditions are implemented for perfect and imperfect electrically conducting boundaries, perfect magnetically conducting boundaries, and absorbing boundaries. The method is validated with the aid of several different types of test cases. Two types of coaxial cables with helical breaks are simulated and the results are discussed.

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.

High-pressure crystal growth and electromagnetic properties of 5d double-perovskite Ca3OsO6

NASA Astrophysics Data System (ADS)

Feng, Hai Luke; Shi, Youguo; Guo, Yanfeng; Li, Jun; Sato, Akira; Sun, Ying; Wang, Xia; Yu, Shan; Sathish, Clastin I.; Yamaura, Kazunari

2013-05-01

Single crystals of the osmium-containing compound Ca3OsO6 have been successfully grown under high-pressure conditions, for the first time. The crystal structure of Ca3OsO6 were characterized as an ordered double-perovskite structure of space group P21/n with the Ca and Os atoms being fully ordered at the perovskite B-site. The electromagnetic analysis shows that the crystal exhibits a semiconductor-like behavior below 300 K and undergoes an antiferromagnetic transition at 50 K.

Accurate isotopic fission yields of electromagnetically induced fission of 238U measured in inverse kinematics at relativistic energies

NASA Astrophysics Data System (ADS)

Pellereau, E.; Taïeb, J.; Chatillon, A.; Alvarez-Pol, H.; Audouin, L.; Ayyad, Y.; Bélier, G.; Benlliure, J.; Boutoux, G.; Caamaño, M.; Casarejos, E.; Cortina-Gil, D.; Ebran, A.; Farget, F.; Fernández-Domínguez, B.; Gorbinet, T.; Grente, L.; Heinz, A.; Johansson, H.; Jurado, B.; Kelić-Heil, A.; Kurz, N.; Laurent, B.; Martin, J.-F.; Nociforo, C.; Paradela, C.; Pietri, S.; Rodríguez-Sánchez, J. L.; Schmidt, K.-H.; Simon, H.; Tassan-Got, L.; Vargas, J.; Voss, B.; Weick, H.

2017-05-01

SOFIA (Studies On Fission with Aladin) is a novel experimental program, dedicated to accurate measurements of fission-fragment isotopic yields. The setup allows us to fully identify, in nuclear charge and mass, both fission fragments in coincidence for the whole fission-fragment range. It was installed at the GSI facility (Darmstadt), to benefit from the relativistic heavy-ion beams available there, and thus to use inverse kinematics. This paper reports on fission yields obtained in electromagnetically induced fission of 238U.

Experimental verification of an eddy-current bearing

NASA Technical Reports Server (NTRS)

Nikolajsen, Jorgen L.

1989-01-01

A new type of electromagnetic bearing was built and tested. It consists of fixed AC-electromagnets in a star formation surrounding a conducting rotor. The bearing works by repulsion due to eddy-currents induced in the rotor. A single bearing is able to fully support a short rotor. The rotor support is inherently stable in all five degrees of freedom. No feedback control is needed. The bearing is also able to accelerate the rotor up to speed and decelerate the rotor back to standstill. The bearing design and the experimentation to verify its capabilities are described.

The Modification of Biocellular Chemical Reactions by Environmental Physicochemicals

NASA Astrophysics Data System (ADS)

Ishido, M.

Environmental risk factors affect human biological system to different extent from modification of biochemical reaction to cellular catastrophe. There are considerable public concerns about electromagnetic fields and endocrine disruptors. Their risk assessments have not been fully achieved because of their scientific uncertainty: electromagnetic fields just modify the bioreaction in the restricted cells and endocrine disruptors are quite unique in that their expression is dependent on the exposure periods throughout a life. Thus, we here describe their molecular characterization to establish the new risk assessments for environmental physicochemicals.

Detailed analysis of the effects of stencil spatial variations with arbitrary high-order finite-difference Maxwell solver

DOE PAGES

Vincenti, H.; Vay, J. -L.

2015-11-22

Due to discretization effects and truncation to finite domains, many electromagnetic simulations present non-physical modifications of Maxwell's equations in space that may generate spurious signals affecting the overall accuracy of the result. Such modifications for instance occur when Perfectly Matched Layers (PMLs) are used at simulation domain boundaries to simulate open media. Another example is the use of arbitrary order Maxwell solver with domain decomposition technique that may under some condition involve stencil truncations at subdomain boundaries, resulting in small spurious errors that do eventually build up. In each case, a careful evaluation of the characteristics and magnitude of themore » errors resulting from these approximations, and their impact at any frequency and angle, requires detailed analytical and numerical studies. To this end, we present a general analytical approach that enables the evaluation of numerical discretization errors of fully three-dimensional arbitrary order finite-difference Maxwell solver, with arbitrary modification of the local stencil in the simulation domain. The analytical model is validated against simulations of domain decomposition technique and PMLs, when these are used with very high-order Maxwell solver, as well as in the infinite order limit of pseudo-spectral solvers. Results confirm that the new analytical approach enables exact predictions in each case. It also confirms that the domain decomposition technique can be used with very high-order Maxwell solver and a reasonably low number of guard cells with negligible effects on the whole accuracy of the simulation.« less

High-Fidelity Simulations of Electromagnetic Propagation and RF Communication Systems

DTIC Science & Technology

2017-05-01

addition to high -fidelity RF propagation modeling, lower-fidelity mod- els, which are less computationally burdensome, are available via a C++ API...expensive to perform, requiring roughly one hour of computer time with 36 available cores and ray tracing per- formed by a single high -end GPU...ER D C TR -1 7- 2 Military Engineering Applied Research High -Fidelity Simulations of Electromagnetic Propagation and RF Communication

Scalable High Performance Computing: Direct and Large-Eddy Turbulent Flow Simulations Using Massively Parallel Computers

NASA Technical Reports Server (NTRS)

Morgan, Philip E.

2004-01-01

This final report contains reports of research related to the tasks "Scalable High Performance Computing: Direct and Lark-Eddy Turbulent FLow Simulations Using Massively Parallel Computers" and "Devleop High-Performance Time-Domain Computational Electromagnetics Capability for RCS Prediction, Wave Propagation in Dispersive Media, and Dual-Use Applications. The discussion of Scalable High Performance Computing reports on three objectives: validate, access scalability, and apply two parallel flow solvers for three-dimensional Navier-Stokes flows; develop and validate a high-order parallel solver for Direct Numerical Simulations (DNS) and Large Eddy Simulation (LES) problems; and Investigate and develop a high-order Reynolds averaged Navier-Stokes turbulence model. The discussion of High-Performance Time-Domain Computational Electromagnetics reports on five objectives: enhancement of an electromagnetics code (CHARGE) to be able to effectively model antenna problems; utilize lessons learned in high-order/spectral solution of swirling 3D jets to apply to solving electromagnetics project; transition a high-order fluids code, FDL3DI, to be able to solve Maxwell's Equations using compact-differencing; develop and demonstrate improved radiation absorbing boundary conditions for high-order CEM; and extend high-order CEM solver to address variable material properties. The report also contains a review of work done by the systems engineer.

Electronically-Controlled Beam-Steering through Vanadium Dioxide Metasurfaces

PubMed Central

Hashemi, Mohammed Reza M.; Yang, Shang-Hua; Wang, Tongyu; Sepúlveda, Nelson; Jarrahi, Mona

2016-01-01

Engineered metamaterials offer unique functionalities for manipulating the spectral and spatial properties of electromagnetic waves in unconventional ways. Here, we report a novel approach for making reconfigurable metasurfaces capable of deflecting electromagnetic waves in an electronically controllable fashion. This is accomplished by tilting the phase front of waves through a two-dimensional array of resonant metasurface unit-cells with electronically-controlled phase-change materials embedded inside. Such metasurfaces can be placed at the output facet of any electromagnetic radiation source to deflect electromagnetic waves at a desired frequency, ranging from millimeter-wave to far-infrared frequencies. Our design does not use any mechanical elements, external light sources, or reflectarrays, creating, for the first time, a highly robust and fully-integrated beam-steering device solution. We demonstrate a proof-of-concept beam-steering metasurface optimized for operation at 100 GHz, offering up to 44° beam deflection in both horizontal and vertical directions. Dynamic control of electromagnetic wave propagation direction through this unique platform could be transformative for various imaging, sensing, and communication applications, among others. PMID:27739471

PICsar: Particle in cell pulsar magnetosphere simulator

NASA Astrophysics Data System (ADS)

Belyaev, Mikhail A.

2016-07-01

PICsar simulates the magnetosphere of an aligned axisymmetric pulsar and can be used to simulate other arbitrary electromagnetics problems in axisymmetry. Written in Fortran, this special relativistic, electromagnetic, charge conservative particle in cell code features stretchable body-fitted coordinates that follow the surface of a sphere, simplifying the application of boundary conditions in the case of the aligned pulsar; a radiation absorbing outer boundary, which allows a steady state to be set up dynamically and maintained indefinitely from transient initial conditions; and algorithms for injection of charged particles into the simulation domain. PICsar is parallelized using MPI and has been used on research problems with 1000 CPUs.

Description of an aircraft lightning and simulated nuclear electromagnetic pulse (NEMP) threat based on experimental data

NASA Technical Reports Server (NTRS)

Rustan, Pedro L., Jr.

1987-01-01

Lightning data obtained by measuring the surface electromagnetic fields on a CV-580 research aircraft during 48 lightning strikes between 1500 and 18,000 feet in central Florida during the summers of 1984 and 1985, and nuclear electromagnetic pulse (NEMP) data obtained by surface electromagnetic field measurements using a 1:74 CV-580 scale model, are presented. From one lightning event, maximum values of 3750 T/s for the time rate of change of the surface magnetic flux density, and 4.7 kA for the peak current, were obtained. From the simulated NEMP test, maximum values of 40,000 T/s for the time rate of change of the surface magnetic flux density, and 90 A/sq m for the total normal current density, were found. The data have application to the development of a military aircraft lightning/NEMP standard.

A New Method for Raising Opening Velocity of Electromagnetic Actuated Vacuum Circuit Breaker

NASA Astrophysics Data System (ADS)

Tsukima, Mitsuru; Takeuchi, Toshie; Koyama, Kenichi; Yoshiyasu, Hajimu

Recently an electromagnetic actuator has been widely used as an operating mechanism for the vacuum circuit breaker (VCB). The opening velocity of the contact is supposed to be strongly related with current interruption performance. This paper presents a simple and new technique that raises opening velocity of the electromagnetic actuated VCB. In order to investigate this reason, we built a numerical simulator that predicts the dynamic characteristics of the VCB contact. It takes into account of the magnetic behavior in the actuator and is also coupled with the external control circuit. According to this simulation, it is shown that it is originated from the sharp rise in the electromagnetic thrust force due to the selective saturation of the magnetic yoke. As the result of our experiments, by this technique the opening velocity was verified to be 1.5 times faster than by the conventional way.

Three dimensional Particle-in-Cell (PIC) simulations of the 67P environment

NASA Astrophysics Data System (ADS)

Divin, Andrey; Deca, Jan; Henri, Pierre; Horanyi, Mihaly; Markidis, Stefano; Lapenta, Giovanni; Olshevsky, Vyacheslav; Eriksson, Anders

2017-04-01

ESA's Rosetta orbiter spacecraft escorted comet 67P/Churyumov-Gerasimenko for two years, carrying 21 scientific instruments. Five of those were dedicated to plasma measurements. The mission revealed for the first time, and in unprecedented detail, the fascinating evolution of a comet and its interaction with our Sun as it races along its 6.45yr elliptical orbit around the Sun. Using a self-consistent 3-D fully kinetic electromagnetic particle-in-cell approach, we focus on the global cometary environment and, in particular, on the collisionless electron-kinetic interaction. We include cometary ions and electrons produced by the ionization of the outgassing cometary atmosphere in addition to the solar wind ion and electron plasma flow. We approximate mass-loading of the cold cometary ion and electron populations using a 1/r relation with distance to the comet with a total neutral production rate of Q = 1026 s-1. Our simulation results disentangle for the first time the kinetic ion and electron dynamics of the solar wind interaction with a weakly outgassing comet. The simulated global structure of the solar wind-comet interaction confirms the results reported in hybrid simulations of the induced cometary magnetosphere. Moreover, we show that cometary and solar wind electrons neutralize the solar wind protons and cometary ions, respectively, in the region of influence around the comet, representing to first order a four-fluid behavior. The electron energy distribution close to the comet is shown to be a mix of cometary and solar wind electrons that appear as, respectively, a thermal and a suprathermal components. Analyzing ion and electron energy distribution functions, and comparing with plasma measurements from ESA's Rosetta mission to comet 67P/Churyumov-Gerasimenko, we conclude that a detailed kinetic treatment of the electron dynamics is critical to fully capture the complex physics of mass-loading plasmas.

Engineering Techniques for Electromagnetic Pulse-Hardness Testing.

DTIC Science & Technology

electromagnetic pulse (EMP). The text describes energy sources, simulation techniques, test instrumentation, and testing techniques. Emphasis is on testing that can be accomplished by engineers with knowledge of electromagnetics and circuits. Complicated systems that require special expertise are described only to acquaint the reader with their characteristics. This text is intended to supplement the testing portion of DNA 2772T ’DNA EMP Awareness Course Notes.’

Electromagnetic radiation as a probe of the initial state and of viscous dynamics in relativistic nuclear collisions

NASA Astrophysics Data System (ADS)

Vujanovic, Gojko; Paquet, Jean-François; Denicol, Gabriel S.; Luzum, Matthew; Jeon, Sangyong; Gale, Charles

2016-07-01

The penetrating nature of electromagnetic signals makes them suitable probes to explore the properties of the strongly interacting medium created in relativistic nuclear collisions. We examine the effects of the initial conditions and shear relaxation time on the spectra and flow coefficients of electromagnetic probes, using an event-by-event 3+1-dimensional viscous hydrodynamic simulation (music).

On a nonlinear state of the electromagnetic ion/ion cyclotron instability

NASA Astrophysics Data System (ADS)

Cremer, M.; Scholer, M.

We have investigated the nonlinear properties of the electromagnetic ion/ion cyclotron instability (EMIIC) by means of hybrid simulations (macroparticle ions, massless electron fluid). The instability is driven by the relative (super-Alfvénic) streaming of two field-aligned ion beams in a low beta plasma (ion thermal pressure to magnetic field pressure) and may be of importance in the plasma sheet boundary layer. As shown in previously reported simulations the waves propagate obliquely to the magnetic field and heat the ions in the perpendicular direction as the relative beam velocity decreases. By running the simulation to large times it can be shown that the large temperature anisotropy leads to the ion cyclotron instability (IC) with parallel propagating Alfvén ion cyclotron waves. This is confirmed by numerically solving the electromagnetic dispersion relation. An application of this property to the plasma sheet boundary layer is discussed.

Distributed source model for the full-wave electromagnetic simulation of nonlinear terahertz generation.

PubMed

Fumeaux, Christophe; Lin, Hungyen; Serita, Kazunori; Withayachumnankul, Withawat; Kaufmann, Thomas; Tonouchi, Masayoshi; Abbott, Derek

2012-07-30

The process of terahertz generation through optical rectification in a nonlinear crystal is modeled using discretized equivalent current sources. The equivalent terahertz sources are distributed in the active volume and computed based on a separately modeled near-infrared pump beam. This approach can be used to define an appropriate excitation for full-wave electromagnetic numerical simulations of the generated terahertz radiation. This enables predictive modeling of the near-field interactions of the terahertz beam with micro-structured samples, e.g. in a near-field time-resolved microscopy system. The distributed source model is described in detail, and an implementation in a particular full-wave simulation tool is presented. The numerical results are then validated through a series of measurements on square apertures. The general principle can be applied to other nonlinear processes with possible implementation in any full-wave numerical electromagnetic solver.

Numerical simulation of magnetic field for compact electromagnet consisting of REBCO coils and iron yoke

NASA Astrophysics Data System (ADS)

You, Shuangrong; Chi, Changxin; Guo, Yanqun; Bai, Chuanyi; Liu, Zhiyong; Lu, Yuming; Cai, Chuanbing

2018-07-01

This paper presents the numerical simulation of a high-temperature superconductor electromagnet consisting of REBCO (RE-Ba2Cu3O7‑x, RE: rare earth) superconducting tapes and a ferromagnetic iron yoke. The REBCO coils with multi-width design are operating at 77 K, with the iron yoke at room temperature, providing a magnetic space with a 32 mm gap between two poles. The finite element method is applied to compute the 3D model of the studied magnet. Simulated results show that the magnet generates a 1.5 T magnetic field at an operating current of 38.7 A, and the spatial inhomogeneity of the field is 0.8% in a Φ–20 mm diameter sphere volume. Compared with the conventional iron electromagnet, the present compact design is more suitable for practical application.

Theoretical modeling, simulation and experimental study of hybrid piezoelectric and electromagnetic energy harvester

NASA Astrophysics Data System (ADS)

Li, Ping; Gao, Shiqiao; Cong, Binglong

2018-03-01

In this paper, performances of vibration energy harvester combined piezoelectric (PE) and electromagnetic (EM) mechanism are studied by theoretical analysis, simulation and experimental test. For the designed harvester, electromechanical coupling modeling is established, and expressions of vibration response, output voltage, current and power are derived. Then, performances of the harvester are simulated and tested; moreover, the power charging rechargeable battery is realized through designed energy storage circuit. By the results, it's found that compared with piezoelectric-only and electromagnetic-only energy harvester, the hybrid energy harvester can enhance the output power and harvesting efficiency; furthermore, at the harmonic excitation, output power of harvester linearly increases with acceleration amplitude increasing; while it enhances with acceleration spectral density increasing at the random excitation. In addition, the bigger coupling strength, the bigger output power is, and there is the optimal load resistance to make the harvester output the maximal power.

Isentropic Compression up to 200 KBars for LX 04, Numerical Simulations and Comparison with Experiments

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

Lefrancois, A.; Hare, D.; L'Eplattenier, P.

2006-02-13

Isentropic compression experiments and numerical simulations on LX-04 (HMX / Viton 85/15) were performed respectively at Z accelerator facility from Sandia National Laboratory and at Lawrence Livermore National Laboratory in order to study the isentrope and associated Hugoniot of this HE. 2D and 3D configurations have been calculated here to test the new beta version of the electromagnetism package coupled with the dynamics in Ls-Dyna and compared with the ICE Z shot 1067 on LX 04. The electromagnetism module is being developed in the general-purpose explicit and implicit finite element program LS-DYNA{reg_sign} in order to perform coupled mechanical/thermal/electromagnetism simulations. Themore » Maxwell equations are solved using a Finite Element Method (FEM) for the solid conductors coupled with a Boundary Element Method (BEM) for the surrounding air (or vacuum). More details can be read in the references.« less

Electromagnetic effects on dynamics of high-beta filamentary structures

DOE PAGES

Lee, Wonjae; Umansky, Maxim V.; Angus, J. R.; ...

2015-01-12

The impacts of the electromagnetic effects on blob dynamics are considered. Electromagnetic BOUT++ simulations on seeded high-beta blobs demonstrate that inhomogeneity of magnetic curvature or plasma pressure along the filament leads to bending of the blob filaments and the magnetic field lines due to increased propagation time of plasma current (Alfvén time). The bending motion can enhance heat exchange between the plasma facing materials and the inner SOL region. The effects of sheath boundary conditions on the part of the blob away from the boundary are also diminished by the increased Alfvén time. Using linear analysis and the BOUT++ simulation,more » it is found that electromagnetic effects in high temperature and high density plasmas reduce the growth rate of resistive drift wave turbulence when resistivity drops below some certain value. Lastly, in the course of blobs motion in the SOL its temperature is reduced, which leads to enhancement of resistive effects, so the blob can switch from electromagnetic to electrostatic regime, where resistive drift wave turbulence become important.« less

Three dimensional δf simulations of beams in the SSC

NASA Astrophysics Data System (ADS)

Koga, J.; Tajima, T.; Machida, S.

1993-12-01

A three dimensional δf strong-strong algorithm has been developed to apply to the study of such effects as space charge and beam-beam interaction phenomena in the Superconducting Super Collider (SSC). The algorithm is obtained from the merging of the particle tracking code Simpsons used for 3 dimensional space charge effects and a δf code. The δf method is used to follow the evolution of the non-gaussian part of the beam distribution. The advantages of this method are twofold. First, the Simpsons code utilizes a realistic accelerator model including synchrotron oscillations and energy ramping in 6 dimensional phase space with electromagnetic fields of the beams calculated using a realistic 3 dimensional field solver. Second, the beams are evolving in the fully self-consistent strong-strong sense with finite particle fluctuation noise is greatly reduced as opposed to the weak-strong models where one beam is fixed.

Stochastic Modeling and Generation of Partially Polarized or Partially Coherent Electromagnetic Waves

NASA Technical Reports Server (NTRS)

Davis, Brynmor; Kim, Edward; Piepmeier, Jeffrey; Hildebrand, Peter H. (Technical Monitor)

2001-01-01

Many new Earth remote-sensing instruments are embracing both the advantages and added complexity that result from interferometric or fully polarimetric operation. To increase instrument understanding and functionality a model of the signals these instruments measure is presented. A stochastic model is used as it recognizes the non-deterministic nature of any real-world measurements while also providing a tractable mathematical framework. A stationary, Gaussian-distributed model structure is proposed. Temporal and spectral correlation measures provide a statistical description of the physical properties of coherence and polarization-state. From this relationship the model is mathematically defined. The model is shown to be unique for any set of physical parameters. A method of realizing the model (necessary for applications such as synthetic calibration-signal generation) is given and computer simulation results are presented. The signals are constructed using the output of a multi-input multi-output linear filter system, driven with white noise.

Performance analysis of FET microwave devices by use of extended spectral-element time-domain method

NASA Astrophysics Data System (ADS)

Sheng, Yijun; Xu, Kan; Wang, Daoxiang; Chen, Rushan

2013-05-01

The extended spectral-element time-domain (SETD) method is employed to analyse field effect transistor (FET) microwave devices. In order to impose the contribution of the FET microwave devices into the electromagnetic simulation, the SETD method is extended by introducing a lumped current term into the vector Helmholtz equation. The change of currents on each lumped component can be expressed by the change of voltage via corresponding models of equivalent circuit. The electric fields around the lumped component must be influenced by the change of voltage on each lumped component, and vice versa. So a global coupling about the EM-circuit can be built directly. The fully explicit solving scheme is maintained in this extended SETD method and the CPU time can be saved spontaneously. Three practical FET microwave devices are analysed in this article. The numerical results demonstrate the ability and accuracy of this method.

The cathode plasma simulation

NASA Astrophysics Data System (ADS)

Suksila, Thada

Since its invention at the University of Stuttgart, Germany in the mid-1960, scientists have been trying to understand and explain the mechanism of the plasma interaction inside the magnetoplasmadynamics (MPD) thruster. Because this thruster creates a larger level of efficiency than combustion thrusters, this MPD thruster is the primary cadidate thruster for a long duration (planetary) spacecraft. However, the complexity of this thruster make it difficult to fully understand the plasma interaction in an MPD thruster while operating the device. That is, there is a great deal of physics involved: the fluid dynamics, the electromagnetics, the plasma dynamics, and the thermodynamics. All of these physics must be included when an MPD thruster operates. In recent years, a computer simulation helped scientists to simulate the experiments by programing the physics theories and comparing the simulation results with the experimental data. Many MPD thruster simulations have been conducted: E. Niewood et al.[5], C. K. J. Hulston et al.[6], K. D. Goodfellow[3], J Rossignol et al.[7]. All of these MPD computer simulations helped the scientists to see how quickly the system responds to the new design parameters. For this work, a 1D MPD thruster simulation was developed to find the voltage drop between the cathode and the plasma regions. Also, the properties such as thermal conductivity, electrical conductivity and heat capacity are temperature and pressure dependent. These two conductivity and heat capacity are usually definded as constant values in many other models. However, this 1D and 2D cylindrical symmetry MPD thruster simulations include both temperature and pressure effects to the electrical, thermal conductivities and heat capacity values interpolated from W. F. Ahtye [4]. Eventhough, the pressure effect is also significant; however, in this study the pressure at 66 Pa was set as a baseline. The 1D MPD thruster simulation includes the sheath region, which is the interface between the plasma and the cathode regions. This sheath model [3] has been fully combined in the 1D simulation. That is, the sheath model calculates the heat flux and the sheath voltage by giving the temperature and the current density. This sheath model must be included in the simulation, as the sheath region is treated differently from the main plasma region. For our 2D cylindrical symmetry simulation, the dimensions of the cathode, the anode, the total current, the pressure, the type of gases, the work function can be changed in the input process as needed for particular interested. Also, the sheath model is still included and fully integrated in this 2D cylindrical symmetry simulation at the cathode surface grids. In addition, the focus of the 2D cylindrical symmetry simulation is to connect the properties on the plasma and the cathode regions on the cathode surface until the MPD thruster reach steady state and estimate the plasma arc attachement edge, electroarc edge, on the cathode surface. Finally, we can understand more about the behavior of an MPD thruster under many different conditions of 2D cylindrical symmetry MPD thruster simulations.

Massively-parallel FDTD simulations to address mask electromagnetic effects in hyper-NA immersion lithography

NASA Astrophysics Data System (ADS)

Tirapu Azpiroz, Jaione; Burr, Geoffrey W.; Rosenbluth, Alan E.; Hibbs, Michael

2008-03-01

In the Hyper-NA immersion lithography regime, the electromagnetic response of the reticle is known to deviate in a complicated manner from the idealized Thin-Mask-like behavior. Already, this is driving certain RET choices, such as the use of polarized illumination and the customization of reticle film stacks. Unfortunately, full 3-D electromagnetic mask simulations are computationally intensive. And while OPC-compatible mask electromagnetic field (EMF) models can offer a reasonable tradeoff between speed and accuracy for full-chip OPC applications, full understanding of these complex physical effects demands higher accuracy. Our paper describes recent advances in leveraging High Performance Computing as a critical step towards lithographic modeling of the full manufacturing process. In this paper, highly accurate full 3-D electromagnetic simulation of very large mask layouts are conducted in parallel with reasonable turnaround time, using a Blue- Gene/L supercomputer and a Finite-Difference Time-Domain (FDTD) code developed internally within IBM. A 3-D simulation of a large 2-D layout spanning 5μm×5μm at the wafer plane (and thus (20μm×20μm×0.5μm at the mask) results in a simulation with roughly 12.5GB of memory (grid size of 10nm at the mask, single-precision computation, about 30 bytes/grid point). FDTD is flexible and easily parallelizable to enable full simulations of such large layout in approximately an hour using one BlueGene/L "midplane" containing 512 dual-processor nodes with 256MB of memory per processor. Our scaling studies on BlueGene/L demonstrate that simulations up to 100μm × 100μm at the mask can be computed in a few hours. Finally, we will show that the use of a subcell technique permits accurate simulation of features smaller than the grid discretization, thus improving on the tradeoff between computational complexity and simulation accuracy. We demonstrate the correlation of the real and quadrature components that comprise the Boundary Layer representation of the EMF behavior of a mask blank to intensity measurements of the mask diffraction patterns by an Aerial Image Measurement System (AIMS) with polarized illumination. We also discuss how this model can become a powerful tool for the assessment of the impact to the lithographic process of a mask blank.

Finite-difference time-domain simulation of electromagnetic bandgap and bi-anisotropic metamaterials

NASA Astrophysics Data System (ADS)

Bray, Matthew G.

The term "Metamaterial" has been introduced into the electromagnetic lexicon in recent years to describe new artificial materials with electromagnetic properties that are not found in naturally occurring materials. Metamaterials exhibit electromagnetic properties that are not observed in its constituent materials, and/or not observed in nature. This thesis will analyze two different classes of metamaterials through the use of the finite-difference time-domain (FDTD) technique. The first class of metamaterials are artificial magnetic conductors (AMC) which approximate the behavior of a perfect magnetic conductor (PMC) over a finite frequency range. The AMC metamaterials are created through the use of an electromagnetic bandgap (EBG) structure. A periodic FDTD code is used to simulate a full-wave model of the metallodielectric EBG structures. The AMCs developed with the aid of the FDTD tool are then used to create low-profile antenna systems consisting of a dipole antenna in close proximity to an AMC surface. Through the use of this FDTD tool, several original contributions were made to the electromagnetic community. These include the first dual-band independently tunable EBG AMC ground plane and the first linearly polarized single-band and dual-band tunable antenna/EBG systems. The second class of materials analyzed are bi-anisotropic metamaterials. Bi-anisotropic media are the largest class of linear media which is able to describe the macroscopic material properties of artificial dielectrics, artificial magnetics, artificial chiral materials, left-handed materials, and other composite materials. The dispersive properties of these materials can be approximated by the oscillator model. This model assumes a Lorentzian frequency profile for the permittivity and permeability and a Condon model for chirality. A new FDTD formulation is introduced which can simulate this type of bi-anisotropic media. This FDTD method incorporates the dispersive material properties through a Z-transform technique derived from the constitutive relations for bi-anisotropic media. This is the first FDTD formulation to be able to simulate dispersive chiral media on a single FDTD grid. This tool was also used to perform the first simulations of dispersive chiral frequency selective surfaces.

Electromagnetically induced transparency (EIT)-like transmission in side-coupled complementary split-ring resonators.

PubMed

Guo, Yinghui; Yan, Lianshan; Pan, Wei; Luo, Bin; Wen, Kunhua; Guo, Zhen; Luo, Xiangang

2012-10-22

We investigate a plasmonic waveguide system based on side-coupled complementary split-ring resonators (CSRR), which exhibits electromagnetically induced transparency (EIT)-like transmission. LC resonance model is utilized to explain the electromagnetic responses of CSRR, which is verified by simulation results of finite difference time domain method. The electromagnetic responses of CSRR can be flexible handled by changing the asymmetry degree of the structure and the width of the metallic baffles. Cascaded CSRRs also have been studied to obtain EIT-like transmission at visible and near-infrared region, simultaneously.

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

Out of time: a possible link between mirror neurons, autism and electromagnetic radiation.

PubMed

Thornton, Ian M

2006-01-01

Recent evidence suggests a link between autism and the human mirror neuron system. In this paper, I argue that temporal disruption from the environment may play an important role in the observed mirror neuron dysfunction, leading in turn to the pattern of deficits associated with autism. I suggest that the developing nervous system of an infant may be particularly prone to temporal noise that can interfere with the initial calibration of brain networks such as the mirror neuron system. The most likely source of temporal noise in the environment is artificially generated electromagnetic radiation. To date, there has been little evidence that electromagnetic radiation poses a direct biological hazard. It is clear, however, that time-varying electromagnetic waves have the potential to temporally modulate the nervous system, particularly when populations of neurons are required to act together. This modulation may be completely harmless for the fully developed nervous system of an adult. For an infant, this same temporal disruption might act to severely delay or disrupt vital calibration processes.

High-Performance Computing for the Electromagnetic Modeling and Simulation of Interconnects

NASA Technical Reports Server (NTRS)

Schutt-Aine, Jose E.

1996-01-01

The electromagnetic modeling of packages and interconnects plays a very important role in the design of high-speed digital circuits, and is most efficiently performed by using computer-aided design algorithms. In recent years, packaging has become a critical area in the design of high-speed communication systems and fast computers, and the importance of the software support for their development has increased accordingly. Throughout this project, our efforts have focused on the development of modeling and simulation techniques and algorithms that permit the fast computation of the electrical parameters of interconnects and the efficient simulation of their electrical performance.

CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Analysis and finite element simulation of electromagnetic heating in the nitride MOCVD reactor

NASA Astrophysics Data System (ADS)

Li, Zhi-Ming; Hao, Yue; Zhang, Jin-Cheng; Xu, Sheng-Rui; Ni, Jin-Yu; Zhou, Xiao-Wei

2009-11-01

Electromagnetic field distribution in the vertical metal organic chemical vapour deposition (MOCVD) reactor is simulated by using the finite element method (FEM). The effects of alternating current frequency, intensity, coil turn number and the distance between the coil turns on the distribution of the Joule heat are analysed separately, and their relations to the value of Joule heat are also investigated. The temperature distribution on the susceptor is also obtained. It is observed that the results of the simulation are in good agreement with previous measurements.

FORMATION OF STABLE MAGNETARS FROM BINARY NEUTRON STAR MERGERS

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

Giacomazzo, Bruno; Perna, Rosalba

2013-07-10

By performing fully general relativistic magnetohydrodynamic simulations of binary neutron star mergers, we investigate the possibility that the end result of the merger is a stable magnetar. In particular, we show that, for a binary composed of two equal-mass neutron stars (NSs) of gravitational mass M {approx} 1.2 M{sub Sun} and equation of state similar to Shen et al. at high densities, the merger product is a stable NS. Such NS is found to be differentially rotating and ultraspinning with spin parameter J/M{sup 2} {approx} 0.86, where J is its total angular momentum, and it is surrounded by a diskmore » of Almost-Equal-To 0.1 M{sub Sun }. While in our global simulations the magnetic field is amplified by about two orders of magnitude, local simulations have shown that hydrodynamic instabilities and the onset of the magnetorotational instability could further increase the magnetic field strength up to magnetar levels. This leads to the interesting possibility that, for some NS mergers, a stable and magnetized NS surrounded by an accretion disk could be formed. We discuss the impact of these new results for the emission of electromagnetic counterparts of gravitational wave signals and for the central engine of short gamma-ray bursts.« less

Fast Flows in the Magnetotail and Energetic Particle Transport: Multiscale Coupling in the Magnetosphere

NASA Astrophysics Data System (ADS)

Lin, Y.; Wang, X.; Fok, M. C. H.; Buzulukova, N.; Perez, J. D.; Chen, L. J.

2017-12-01

The interaction between the Earth's inner and outer magnetospheric regions associated with the tail fast flows is calculated by coupling the Auburn 3-D global hybrid simulation code (ANGIE3D) to the Comprehensive Inner Magnetosphere/Ionosphere (CIMI) model. The global hybrid code solves fully kinetic equations governing the ions and a fluid model for electrons in the self-consistent electromagnetic field of the dayside and night side outer magnetosphere. In the integrated computation model, the hybrid simulation provides the CIMI model with field data in the CIMI 3-D domain and particle data at its boundary, and the transport in the inner magnetosphere is calculated by the CIMI model. By joining the two existing codes, effects of the solar wind on particle transport through the outer magnetosphere into the inner magnetosphere are investigated. Our simulation shows that fast flows and flux ropes are localized transients in the magnetotail plasma sheet and their overall structures have a dawn-dusk asymmetry. Strong perpendicular ion heating is found at the fast flow braking, which affects the earthward transport of entropy-depleted bubbles. We report on the impacts from the temperature anisotropy and non-Maxwellian ion distributions associated with the fast flows on the ring current and the convection electric field.

Development of a 3D numerical code to calculate the trajectories of the blow off electrons emitted by a vacuum surface discharge: Application to the study of the electromagnetic interference induced on a spacecraft

NASA Astrophysics Data System (ADS)

Froger, Etienne

1993-05-01

A description of the electromagnetic behavior of a satellite subjected to an electric discharge is given using a specially developed numerical code. One of the particularities of vacuum discharges, obtained by irradiation of polymers, is the intense emission of electrons into the spacecraft environment. Electromagnetic radiation, associated with the trajectories of the particles around the spacecraft, is considered as the main source of the interference observed. In the absence of accurate orbital data and realistic ground tests, the assessment of these effects requires numerical simulation of the interaction between this electron source and the spacecraft. This is done by the GEODE particle code which is applied to characteristic configurations in order to estimate the spacecraft response to a discharge, which is simulated from a vacuum discharge model designed in laboratory. The spacecraft response to a current injection is simulated by the ALICE numerical three dimensional code. The comparison between discharge and injection effects, from the results given by the two codes, illustrates the representativity of electromagnetic susceptibility tests and the main parameters for their definition.

Full PIC simulations of solar radio emission

NASA Astrophysics Data System (ADS)

Sgattoni, A.; Henri, P.; Briand, C.; Amiranoff, F.; Riconda, C.

2017-12-01

Solar radio emissions are electromagnetic (EM) waves emitted in the solar wind plasma as a consequence of electron beams accelerated during solar flares or interplanetary shocks such as ICMEs. To describe their origin, a multi-stage model has been proposed in the 60s which considers a succession of non-linear three-wave interaction processes. A good understanding of the process would allow to infer the kinetic energy transfered from the electron beam to EM waves, so that the radio waves recorded by spacecraft can be used as a diagnostic for the electron beam.Even if the electrostatic problem has been extensively studied, full electromagnetic simulations were attempted only recently. Our large scale 2D-3V electromagnetic PIC simulations allow to identify the generation of both electrostatic and EM waves originated by the succession of plasma instabilities. We tested several configurations varying the electron beam density and velocity considering a background plasma of uniform density. For all the tested configurations approximately 105 of the electron-beam kinetic energy is transfered into EM waves emitted in all direction nearly isotropically. With this work we aim to design experiments of laboratory astrophysics to reproduce the electromagnetic emission process and test its efficiency.

Electromagnetic shielding of thermal protection system for hypersonic vehicles

NASA Astrophysics Data System (ADS)

Albano, M.; Micheli, D.; Gradoni, G.; Morles, R. B.; Marchetti, M.; Moglie, F.; Mariani Primiani, V.

2013-06-01

The numerical simulation and the measurement of electromagnetic shielding at microwave frequencies of thermal protection system for hypersonic vehicles is presented using nested reverberation chamber. An example of a possible thermal protection system for a re-entry vehicle is presented. This system based on carbon material is electromagnetically characterized. The characterization takes into account not only the materials but also the final assembly configuration of the thermal protection system. The frequency range is 2-8 GHz. The results of measurements and simulations show that the microwave shielding effectiveness of carbon materials is above 60 dB for a single tile and that the tile inter-distance is able to downgrade the shielding effectiveness on the average to about 40 dB.

Combining electromagnetic gyro-kinetic particle-in-cell simulations with collisions

NASA Astrophysics Data System (ADS)

Slaby, Christoph; Kleiber, Ralf; Könies, Axel

2017-09-01

It has been an open question whether for electromagnetic gyro-kinetic particle-in-cell (PIC) simulations pitch-angle collisions and the recently introduced pullback transformation scheme (Mishchenko et al., 2014; Kleiber et al., 2016) are consistent. This question is positively answered by comparing the PIC code EUTERPE with an approach based on an expansion of the perturbed distribution function in eigenfunctions of the pitch-angle collision operator (Legendre polynomials) to solve the electromagnetic drift-kinetic equation with collisions in slab geometry. It is shown how both approaches yield the same results for the frequency and damping rate of a kinetic Alfvén wave and how the perturbed distribution function is substantially changed by the presence of pitch-angle collisions.

FDTD simulations of localization and enhancements on fractal plasmonics nanostructures.

PubMed

Buil, Stéphanie; Laverdant, Julien; Berini, Bruno; Maso, Pierre; Hermier, Jean-Pierre; Quélin, Xavier

2012-05-21

A parallelized 3D FDTD (Finite-Difference Time-Domain) solver has been used to study the near-field electromagnetic intensity upon plasmonics nanostructures. The studied structures are obtained from AFM (Atomic Force Microscopy) topography measured on real disordered gold layers deposited by thermal evaporation under ultra-high vacuum. The simulation results obtained with these 3D metallic nanostructures are in good agreement with previous experimental results: the localization of the electromagnetic intensity in subwavelength areas ("hot spots") is demonstrated; the spectral and polarization dependences of the position of these "hot spots" are also satisfactory; the enhancement factors obtained are realistic compared to the experimental ones. These results could be useful to further our understanding of the electromagnetic behavior of random metal layers.

Gyrofluid theory and simulation of electromagnetic turbulence and transport in tokamak plasmas

NASA Astrophysics Data System (ADS)

Snyder, Philip Benjamin

1999-11-01

Turbulence and transport in toroidal plasmas is studied via the development of an electromagnetic gyrofluid model, and its implementation in realistic nonlinear simulations. This work extends earlier electrostatic gyrofluid models to include magnetic fluctuations and non-adiabatic passing electron dynamics. A new set of electron fluid equations is derived from the drift kinetic equation, via an expansion in the electron-ion mass ratio. These electron equations include descriptions of linear and nonlinear drift motion, Landau damping, and electron-ion collisions. Ion moment equations are derived from the electromagnetic gyrokinetic equation, and the gyrokinetic Poisson's Equation and Ampere's Law close the system. The model is benchmarked with linear gyrokinetic calculations, and good agreement is found for both the finite-β ion temperature gradient (ITG) and kinetic Alfvén ballooning (KBM) instabilities. Nonlinear simulations of ITG and KBM-driven turbulence are performed in toroidal flux tube geometry at a range of values of plasma β, and electromagnetic effects are found to significantly impact turbulent heat and particle transport. At low values of β, transport is reduced, as expected due to the finite-β stabilization of the ITG mode. However, as β approaches the Ideal-MHD stability threshold, transport can increase. In the presence of dissipation provided by a model of electron Landau damping and electron-ion collisions, this transport increase can be quite dramatic. Finally, the results of the simulations are compared to tokamak experiments, and encouraging agreement is found with measured density and temperature fluctuation spectra. Direct comparisons of transport fluxes reveal that electromagnetic effects are important at characteristic edge parameters, bringing predicted fluxes more closely in line with observations.

Simulation of radiation energy release in air showers

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

Glaser, Christian; Erdmann, Martin; Hörandel, Jörg R.

2016-09-01

A simulation study of the energy released by extensive air showers in the form of MHz radiation is performed using the CoREAS simulation code. We develop an efficient method to extract this radiation energy from air-shower simulations. We determine the longitudinal profile of the radiation energy release and compare it to the longitudinal profile of the energy deposit by the electromagnetic component of the air shower. We find that the radiation energy corrected for the geometric dependence of the geomagnetic emission scales quadratically with the energy in the electromagnetic component of the air shower with a second-order dependence on themore » atmospheric density at the position of the maximum shower development X {sub max}. In a measurement where X {sub max} is not accessible, this second order dependence can be approximated using the zenith angle of the incoming direction of the air shower with only a minor loss in accuracy. Our method results in an intrinsic uncertainty of 4% in the determination of the energy in the electromagnetic air-shower component, which is well below current experimental uncertainties.« less

Intrinsic line shape of electromagnetic radiation from a stack of intrinsic Josephson junctions synchronized by an internal cavity resonance

NASA Astrophysics Data System (ADS)

Koshelev, Alexei

2013-03-01

Stacks of intrinsic Josephson-junctions are realized in mesas fabricated out of layered superconducting single crystals, such as Bi2Sr2CaCu2O8 (BSCCO). Synchronization of phase oscillations in different junctions can be facilitated by the coupling to the internal cavity mode leading to powerful and coherent electromagnetic radiation in the terahertz frequency range. An important characteristic of this radiation is the shape of the emission line. A finite line width appears due to different noise sources leading to phase diffusion. We investigated the intrinsic line shape caused by the thermal noise for a mesa fabricated on the top of a BSCCO single crystal. In the ideal case of fully synchronized stack the finite line width is coming from two main contributions, the quasiparticle-current noise inside the mesa and the fluctuating radiation in the base crystal. We compute both contributions and conclude that for realistic mesa's parameters the second mechanism typically dominates. The role of the cavity quality factor in the emission line spectrum is clarified. Analytical results were verified by numerical simulations. In real mesa structures part of the stack may not be synchronized and chaotic dynamics of unsynchronized junctions may determine the real line width. Work supported by UChicago Argonne, LLC, under contract No. DE-AC02-06CH11357.

Theoretical Study of Wave Particle Correlation Measurement via 1-D Electromagnetic Particle Simulation

NASA Astrophysics Data System (ADS)

Ueda, Yoshikatsu; Omura, Yoshiharu; Kojima, Hiro

Spacecraft observation is essentially "one-point measurement", while numerical simulation can reproduce a whole system of physical processes on a computer. By performing particle simulations of plasma wave instabilities and calculating correlation of waves and particles observed at a single point, we examine how well we can infer the characteristics of the whole system by a one-point measurement. We perform various simulation runs with different plasma parameters using one-dimensional electromagnetic particle code (KEMPO1) and calculate 'E dot v' or other moments at a single point. We find good correlation between the measurement and the macroscopic fluctuations of the total simulation region. We make use of the results of the computer experiments in our system design of new instruments 'One-chip Wave Particle Interaction Analyzer (OWPIA)'.

Performance of Flow and Heat Transfer in a Hot-Dip Round Coreless Galvanizing Bath

NASA Astrophysics Data System (ADS)

Yue, Qiang; Zhang, Chengbo; Xu, Yong; Zhou, Li; Kong, Hui; Wang, Jia

2017-04-01

Flow field in a coreless hot-dip galvanizing pot was investigated through a water modeling experiment. The corresponding velocity vector was measured using an acoustic Doppler velocimeter. The flow field of molten zinc in the bath was also analyzed. Steel strip velocities from 1.7 to 2.7 m/s were adopted to determine the effect of steel strip velocity on the molten zinc flow in the bath. A large vortex filled the space at the right side of the sink roll, under linear speed from 1.0 to 2.7 m/s and width from 1.0 to 1.3 m of the steel strip, because of the effects of wall and shear stress. The results of the water modeling experiment were compared with those of numerical simulations. In the simulation, Maxwell equations were solved using finite element method to obtain magnetic flux density, electromagnetic force, and Joule heating. The Joule heating rate reached the maximum and minimum values near the side wall and at the core of the bath, respectively, because of the effect of skin and proximity. In an industrial-sized model, the molten zinc flow and temperature fields driven by electromagnetic force and Joule heating in the inductor of a coreless galvanizing bath were numerically simulated. The results indicated that the direction of electromagnetic force concentrated at the center of the galvanizing pot horizontal planes and exerted a pinch effect on molten zinc. Consequently, molten zinc in the pot was stirred by electromagnetic force. Under molten zinc flow and electromagnetic force stirring, the temperature of the molten zinc became homogeneous throughout the bath. This study provides a basis for optimizing electromagnetic fields in coreless induction pot and fine-tuning the design of steel strip parameters.

Study on coupled shock absorber system using four electromagnetic dampers

NASA Astrophysics Data System (ADS)

Fukumori, Y.; Hayashi, R.; Okano, H.; Suda, Y.; Nakano, K.

2016-09-01

Recently, the electromagnetic damper, which is composed of an electric motor, a ball screw, and a nut, was proposed. The electromagnetic damper has high responsiveness, controllability, and energy saving performance. It has been reported that it improved ride comfort and drivability. In addition, the authors have proposed a coupling method of two electromagnetic dampers. The method enables the characteristics of bouncing and rolling or pitching motion of a vehicle to be tuned independently. In this study, the authors increase the number of coupling of electromagnetic dampers from two to four, and propose a method to couple four electromagnetic dampers. The proposed method enables the characteristics of bouncing, rolling and pitching motion of a vehicle to be tuned independently. Basic experiments using proposed circuit and motors and numerical simulations of an automobile equipped with the proposed coupling electromagnetic damper are carried out. The results indicate the proposed method is effective.

Real-time closed-loop simulation and upset evaluation of control systems in harsh electromagnetic environments

NASA Technical Reports Server (NTRS)

Belcastro, Celeste M.

1989-01-01

Digital control systems for applications such as aircraft avionics and multibody systems must maintain adequate control integrity in adverse as well as nominal operating conditions. For example, control systems for advanced aircraft, and especially those with relaxed static stability, will be critical to flight and will, therefore, have very high reliability specifications which must be met regardless of operating conditions. In addition, multibody systems such as robotic manipulators performing critical functions must have control systems capable of robust performance in any operating environment in order to complete the assigned task reliably. Severe operating conditions for electronic control systems can result from electromagnetic disturbances caused by lightning, high energy radio frequency (HERF) transmitters, and nuclear electromagnetic pulses (NEMP). For this reason, techniques must be developed to evaluate the integrity of the control system in adverse operating environments. The most difficult and illusive perturbations to computer-based control systems that can be caused by an electromagnetic environment (EME) are functional error modes that involve no component damage. These error modes are collectively known as upset, can occur simultaneously in all of the channels of a redundant control system, and are software dependent. Upset studies performed to date have not addressed the assessment of fault tolerant systems and do not involve the evaluation of a control system operating in a closed-loop with the plant. A methodology for performing a real-time simulation of the closed-loop dynamics of a fault tolerant control system with a simulated plant operating in an electromagnetically harsh environment is presented. In particular, considerations for performing upset tests on the controller are discussed. Some of these considerations are the generation and coupling of analog signals representative of electromagnetic disturbances to a control system under test, analog data acquisition, and digital data acquisition from fault tolerant systems. In addition, a case study of an upset test methodology for a fault tolerant electromagnetic aircraft engine control system is presented.

Numerical Study of Magnetic Damping During Unidirectional Solidification

NASA Technical Reports Server (NTRS)

Li, Ben Q.

1997-01-01

A fully 3-D numerical model is developed to represent magnetic damping of complex fluid flow, heat transfer and electromagnetic field distributions in a melt cavity. The model is developed based on our in-house finite element code for the fluid flow, heat transfer and electromagnetic field calculations. The computer code has been tested against benchmark test problems that are solved by other commercial codes as well as analytical solutions whenever available. The numerical model is tested against numerical and experimental results for water reported in literature. With the model so tested, various numerical simulations are carried out for the Sn-35.5% Pb melt convection and temperature distribution in a cylindrical cavity with and without the presence of a transverse magnetic field. Numerical results show that magnetic damping can be effectively applied to reduce turbulence and flow levels in the melt undergoing solidification and over a certain threshold value a higher magnetic field resulted in a higher velocity reduction. It is found also that for a fully 3-D representation of the magnetic damping effects, the electric field induced in the melt by the applied DC magnetic field does not vanish, as some researchers suggested, and must be included even for molten metal and semiconductors. Also, for the study of the melt flow instability, a long enough time has to be applied to ensure the final fluid flow recirculation pattern. Moreover, our numerical results suggested that there seems to exist a threshold value of applied magnetic field, above which magnetic damping becomes possible and below which the convection in the melt is actually enhanced. Because of the limited financial resource allocated for the project, we are unable to carry out extensive study on this effect, which should warrant further theoretical and experimental study. In that endeavor, the developed numerical model should be very useful; and the model should serve as a useful tool for exploring necessary design parameters for planning magnetic damping experiments and interpreting the experimental results.

Conformal Electromagnetic Particle in Cell: A Review

DOE PAGES

Meierbachtol, Collin S.; Greenwood, Andrew D.; Verboncoeur, John P.; ...

2015-10-26

We review conformal (or body-fitted) electromagnetic particle-in-cell (EM-PIC) numerical solution schemes. Included is a chronological history of relevant particle physics algorithms often employed in these conformal simulations. We also provide brief mathematical descriptions of particle-tracking algorithms and current weighting schemes, along with a brief summary of major time-dependent electromagnetic solution methods. Several research areas are also highlighted for recommended future development of new conformal EM-PIC methods.

Numerical studies on the electromagnetic properties of the nonlinear Lorentz Computational model for the dielectric media

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

Abe, H.; Okuda, H.

We study linear and nonlinear properties of a new computer simulation model developed to study the propagation of electromagnetic waves in a dielectric medium in the linear and nonlinear regimes. The model is constructed by combining a microscopic model used in the semi-classical approximation for the dielectric media and the particle model developed for the plasma simulations. It is shown that the model may be useful for studying linear and nonlinear wave propagation in the dielectric media.

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

Zhang Yu; Liu Jinliang; Fan Xuliang

In this paper, the electromagnetic dispersion theory and the classic telegraph equations were combined to calculate the important parameters of the helical Blumlein pulse forming line (BPFL) of accelerator based on tape helix. In the work band of the BPFL at several hundred ns range, electromagnetic dispersion characteristics were almost determined by the zeroth harmonic. In order to testify the dispersion theory of BPFL in this paper, filling dielectrics, such as de-ionized water, transformer oil, and air were employed in the helical BPFL, respectively. Parameters such as capacitance, inductance, characteristic impedance, and pulse duration of the BPFL were calculated. Effectsmore » of dispersion on these parameters were analyzed. Circuit simulation and electromagnetic simulation were carried out to prove these parameters of BPFL filled with these three kinds of dielectrics, respectively. The accelerator system was set up, and experimental results also corresponded to the theoretical calculations. The average theoretical errors of impedances and pulse durations were 3.5% and 3.4%, respectively, which proved the electromagnetic dispersion analyses in this paper.« less

Molding acoustic, electromagnetic and water waves with a single cloak

PubMed Central

Xu, Jun; Jiang, Xu; Fang, Nicholas; Georget, Elodie; Abdeddaim, Redha; Geffrin, Jean-Michel; Farhat, Mohamed; Sabouroux, Pierre; Enoch, Stefan; Guenneau, Sébastien

2015-01-01

We describe two experiments demonstrating that a cylindrical cloak formerly introduced for linear surface liquid waves works equally well for sound and electromagnetic waves. This structured cloak behaves like an acoustic cloak with an effective anisotropic density and an electromagnetic cloak with an effective anisotropic permittivity, respectively. Measured forward scattering for pressure and magnetic fields are in good agreement and provide first evidence of broadband cloaking. Microwave experiments and 3D electromagnetic wave simulations further confirm reduced forward and backscattering when a rectangular metallic obstacle is surrounded by the structured cloak for cloaking frequencies between 2.6 and 7.0 GHz. This suggests, as supported by 2D finite element simulations, sound waves are cloaked between 3 and 8 KHz and linear surface liquid waves between 5 and 16 Hz. Moreover, microwave experiments show the field is reduced by 10 to 30 dB inside the invisibility region, which suggests the multi-wave cloak could be used as a protection against water, sonic or microwaves. PMID:26057934

Molding acoustic, electromagnetic and water waves with a single cloak.

PubMed

Xu, Jun; Jiang, Xu; Fang, Nicholas; Georget, Elodie; Abdeddaim, Redha; Geffrin, Jean-Michel; Farhat, Mohamed; Sabouroux, Pierre; Enoch, Stefan; Guenneau, Sébastien

2015-06-09

We describe two experiments demonstrating that a cylindrical cloak formerly introduced for linear surface liquid waves works equally well for sound and electromagnetic waves. This structured cloak behaves like an acoustic cloak with an effective anisotropic density and an electromagnetic cloak with an effective anisotropic permittivity, respectively. Measured forward scattering for pressure and magnetic fields are in good agreement and provide first evidence of broadband cloaking. Microwave experiments and 3D electromagnetic wave simulations further confirm reduced forward and backscattering when a rectangular metallic obstacle is surrounded by the structured cloak for cloaking frequencies between 2.6 and 7.0 GHz. This suggests, as supported by 2D finite element simulations, sound waves are cloaked between 3 and 8 KHz and linear surface liquid waves between 5 and 16 Hz. Moreover, microwave experiments show the field is reduced by 10 to 30 dB inside the invisibility region, which suggests the multi-wave cloak could be used as a protection against water, sonic or microwaves.

Design of electromagnetic refractor and phase transformer using coordinate transformation theory.

PubMed

Lin, Lan; Wang, Wei; Cui, Jianhua; Du, Chunlei; Luo, Xiangang

2008-05-12

We designed an electromagnetic refractor and a phase transformer using form-invariant coordinate transformation of Maxwell's equations. The propagation direction of electromagnetic energy in these devices can be modulated as desired. Unlike the conventional dielectric refractor, electromagnetic fields at our refraction boundary do not conform to the Snell's law in isotropic materials and the impedance at this boundary is matched which makes the reflection extremely low; and the transformation of the wave front from cylindrical to plane can be realized in the phase transformer with a slab structure. Two dimensional finite-element simulations were performed to confirm the theoretical results.

Fully kinetic simulations of dense plasma focus Z-pinch devices.

PubMed

Schmidt, A; Tang, V; Welch, D

2012-11-16

Dense plasma focus Z-pinch devices are sources of copious high energy electrons and ions, x rays, and neutrons. The mechanisms through which these physically simple devices generate such high-energy beams in a relatively short distance are not fully understood. We now have, for the first time, demonstrated a capability to model these plasmas fully kinetically, allowing us to simulate the pinch process at the particle scale. We present here the results of the initial kinetic simulations, which reproduce experimental neutron yields (~10(7)) and high-energy (MeV) beams for the first time. We compare our fluid, hybrid (kinetic ions and fluid electrons), and fully kinetic simulations. Fluid simulations predict no neutrons and do not allow for nonthermal ions, while hybrid simulations underpredict neutron yield by ~100x and exhibit an ion tail that does not exceed 200 keV. Only fully kinetic simulations predict MeV-energy ions and experimental neutron yields. A frequency analysis in a fully kinetic simulation shows plasma fluctuations near the lower hybrid frequency, possibly implicating lower hybrid drift instability as a contributor to anomalous resistivity in the plasma.

FDTD simulation of field performance in reverberation chamber excited by two excitation antennas

NASA Astrophysics Data System (ADS)

Wang, Song; Wu, Zhan-cheng; Cui, Yao-zhong

2013-03-01

The excitation source is one of the critical items that determine the electromagnetic fields in a reverberation chamber (RC). In order to optimize the electromagnetic fields performance, a new method of exciting RC with two antennas is proposed based on theoretical analysis. The full 3D simulation of RC is carried out by the finite difference time domain (FDTD) method on two excitation conditions of one antenna and two antennas. The broadband response of RC is obtained by fast Fourier transformation (FFT) after only one simulation. Numerical data show that the field uniformity in the test space is improved on the condition of two transmitting antennas while the normalized electric fields decreased slightly compared to the one antenna condition. It is straightforward to recognize that two antennas excitation can reduce the demands on power amplifier as the total input power is split among the two antennas, and consequently the cost of electromagnetic compatibility (EMC) test in large-scale RC can be reduced.

Two-Speed Gearbox Dynamic Simulation Predictions and Test Validation

NASA Technical Reports Server (NTRS)

Lewicki, David G.; DeSmidt, Hans; Smith, Edward C.; Bauman, Steven W.

2010-01-01

Dynamic simulations and experimental validation tests were performed on a two-stage, two-speed gearbox as part of the drive system research activities of the NASA Fundamental Aeronautics Subsonics Rotary Wing Project. The gearbox was driven by two electromagnetic motors and had two electromagnetic, multi-disk clutches to control output speed. A dynamic model of the system was created which included a direct current electric motor with proportional-integral-derivative (PID) speed control, a two-speed gearbox with dual electromagnetically actuated clutches, and an eddy current dynamometer. A six degree-of-freedom model of the gearbox accounted for the system torsional dynamics and included gear, clutch, shaft, and load inertias as well as shaft flexibilities and a dry clutch stick-slip friction model. Experimental validation tests were performed on the gearbox in the NASA Glenn gear noise test facility. Gearbox output speed and torque as well as drive motor speed and current were compared to those from the analytical predictions. The experiments correlate very well with the predictions, thus validating the dynamic simulation methodologies.

Global simulation of the induction heating TSSG process of SiC for the effects of Marangoni convection, free surface deformation and seed rotation

NASA Astrophysics Data System (ADS)

Yamamoto, Takuya; Okano, Yasunori; Ujihara, Toru; Dost, Sadik

2017-07-01

A global numerical simulation was performed for the induction heating Top-Seeded Solution Growth (TSSG) process of SiC. Analysis included the furnace and growth melt. The effects of interfacial force due to free surface tension gradient, the RF coil-induced electromagnetic body force, buoyancy, melt free surface deformation, and seed rotation were examined. The simulation results showed that the contributions of free surface tension gradient and the electromagnetic body force to the melt flow are significant. Marangoni convection affects the growth process adversely by making the melt flow downward in the region under the seed crystal. This downward flow reduces carbon flux into the seed and consequently lowers growth rate. The effects of free surface deformation and seed rotation, although positive, are not so significant compared with those of free surface tension gradient and the electromagnetic body force. Due to the small size of the melt the contribution of buoyancy is also small.

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 ...

Comparison of Commercial Electromagnetic Interface Test Techniques to NASA Electromagnetic Interference Test Techniques

NASA Astrophysics Data System (ADS)

Smith, V.

2000-11-01

This report documents the development of analytical techniques required for interpreting and comparing space systems electromagnetic interference test data with commercial electromagnetic interference test data using NASA Specification SSP 30237A "Space Systems Electromagnetic Emission and Susceptibility Requirements for Electromagnetic Compatibility." The PSpice computer simulation results and the laboratory measurements for the test setups under study compare well. The study results, however, indicate that the transfer function required to translate test results of one setup to another is highly dependent on cables and their actual layout in the test setup. Since cables are equipment specific and are not specified in the test standards, developing a transfer function that would cover all cable types (random, twisted, or coaxial), sizes (gauge number and length), and layouts (distance from the ground plane) is not practical.

Design and analysis of an electromagnetic turnout for the superconducting Maglev system

NASA Astrophysics Data System (ADS)

Li, Y. J.; Dai, Q.; Zhang, Y.; Wang, H.; Chen, Z.; Sun, R. X.; Zheng, J.; Deng, C. Y.; Deng, Z. G.

2016-09-01

Turnout is a crucial track junction device of the ground rail transportation system. For high temperature superconducting (HTS) Maglev system, the permanent magnet guideway (PMG) makes the strong magnetic force existing between rail segments, which may cause moving difficulties and increase the operation cost when switching a PMG. In this paper, a non-mechanical 'Y' shaped Halbach-type electromagnetic turnout was proposed. By replacing the PMs with electromagnets, the turnout can guide the maglev vehicle running into another PMG by simply controlling the current direction of electromagnets. The material and structure parameters of the electromagnets were optimized by simulation. The results show that the optimized electromagnet can keep the magnetic field above it as strong as the PMs', meanwhile feasible for design and manufacture. This work provides valuable references for the future design in non-mechanical PMG turnout.

Comparison of Commercial Electromagnetic Interface Test Techniques to NASA Electromagnetic Interference Test Techniques

NASA Technical Reports Server (NTRS)

Smith, V.; Minor, J. L. (Technical Monitor)

2000-01-01

This report documents the development of analytical techniques required for interpreting and comparing space systems electromagnetic interference test data with commercial electromagnetic interference test data using NASA Specification SSP 30237A "Space Systems Electromagnetic Emission and Susceptibility Requirements for Electromagnetic Compatibility." The PSpice computer simulation results and the laboratory measurements for the test setups under study compare well. The study results, however, indicate that the transfer function required to translate test results of one setup to another is highly dependent on cables and their actual layout in the test setup. Since cables are equipment specific and are not specified in the test standards, developing a transfer function that would cover all cable types (random, twisted, or coaxial), sizes (gauge number and length), and layouts (distance from the ground plane) is not practical.

Strange and Charge Symmetry Violating Electromagnetic Form Factors of the Nucleon

NASA Astrophysics Data System (ADS)

Shanahan, P. E.

We summarise recent work based on lattice QCD simulations of the electromagnetic form factors of the octet baryons from the CSSM/QCDSF/UKQCD collaborations. After an analysis of the simulation results using techniques to approach the infinite volume limit and the physical pseudoscalar masses at non-zero momentum transfer, the extrapolated proton and neutron form factors are found to be in excellent agreement with those extracted from experiment. Given the success of these calculations, we describe how the strange electromagnetic form factors may be estimated from these results under the same assumption of charge symmetry used in experimental determinations of those quantities. Motivated by the necessity of that assumption, we explore a method for determining the size of charge symmetry breaking effects using the same lattice results.

Science & Technology Review November 2007

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

Chinn, D J

2007-10-16

This month's issue has the following articles: (1) Simulating the Electromagnetic World--Commentary by Steven R. Patterson; (2) A Code to Model Electromagnetic Phenomena--EMSolve, a Livermore supercomputer code that simulates electromagnetic fields, is helping advance a wide range of research efforts; (3) Characterizing Virulent Pathogens--Livermore researchers are developing multiplexed assays for rapid detection of pathogens; (4) Imaging at the Atomic Level--A powerful new electron microscope at the Laboratory is resolving materials at the atomic level for the first time; (5) Scientists without Borders--Livermore scientists lend their expertise on peaceful nuclear applications to their counterparts in other countries; and (6) Probing Deepmore » into the Nucleus--Edward Teller's contributions to the fast-growing fields of nuclear and particle physics were part of a physics golden age.« less

Validation of a hybrid electromagnetic-piezoelectric vibration energy harvester

NASA Astrophysics Data System (ADS)

Edwards, Bryn; Hu, Patrick A.; Aw, Kean C.

2016-05-01

This paper presents a low frequency vibration energy harvester with contact based frequency up-conversion and hybrid electromagnetic-piezoelectric transduction. An electromagnetic generator is proposed as a power source for low power wearable electronic devices, while a second piezoelectric generator is investigated as a potential power source for a power conditioning circuit for the electromagnetic transducer output. Simulations and experiments are conducted in order to verify the behaviour of the device under harmonic as well as wide-band excitations across two key design parameters—the length of the piezoelectric beam and the excitation frequency. Experimental results demonstrated that the device achieved a power output between 25.5 and 34 μW at an root mean squared (rms) voltage level between 16 and 18.5 mV for the electromagnetic transducer in the excitation frequency range of 3-7 Hz, while the output power of the piezoelectric transducer ranged from 5 to 10.5 μW with a minimum peak-to-peak output voltage of 6 V. A multivariate model validation was performed between experimental and simulation results under wide-band excitation in terms of the rms voltage outputs of the electromagnetic and piezoelectric transducers, as well as the peak-to-peak voltage output of the piezoelectric transducer, and it is found that the experimental data fit the model predictions with a minimum probability of 63.4% across the parameter space.

Passive wireless antenna sensor for strain and crack sensing—electromagnetic modeling, simulation, and testing

NASA Astrophysics Data System (ADS)

Yi, Xiaohua; Cho, Chunhee; Cooper, James; Wang, Yang; Tentzeris, Manos M.; Leon, Roberto T.

2013-08-01

This research investigates a passive wireless antenna sensor designed for strain and crack sensing. When the antenna experiences deformation, the antenna shape changes, causing a shift in the electromagnetic resonance frequency of the antenna. A radio frequency identification (RFID) chip is adopted for antenna signal modulation, so that a wireless reader can easily distinguish the backscattered sensor signal from unwanted environmental reflections. The RFID chip captures its operating power from an interrogation electromagnetic wave emitted by the reader, which allows the antenna sensor to be passive (battery-free). This paper first reports the latest simulation results on radiation patterns, surface current density, and electromagnetic field distribution. The simulation results are followed with experimental results on the strain and crack sensing performance of the antenna sensor. Tensile tests show that the wireless antenna sensor can detect small strain changes lower than 20 με, and can perform well at large strains higher than 10 000 με. With a high-gain reader antenna, the wireless interrogation distance can be increased up to 2.1 m. Furthermore, an array of antenna sensors is capable of measuring the strain distribution in close proximity. During emulated crack and fatigue crack tests, the antenna sensor is able to detect the growth of a small crack.

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.

Integrated analysis of large space systems

NASA Technical Reports Server (NTRS)

Young, J. P.

1980-01-01

Based on the belief that actual flight hardware development of large space systems will necessitate a formalized method of integrating the various engineering discipline analyses, an efficient highly user oriented software system capable of performing interdisciplinary design analyses with tolerable solution turnaround time is planned Specific analysis capability goals were set forth with initial emphasis given to sequential and quasi-static thermal/structural analysis and fully coupled structural/control system analysis. Subsequently, the IAC would be expanded to include a fully coupled thermal/structural/control system, electromagnetic radiation, and optical performance analyses.

Impact compressive and bending behaviour of rocks accompanied by electromagnetic phenomena.

PubMed

Kobayashi, Hidetoshi; Horikawa, Keitaro; Ogawa, Kinya; Watanabe, Keiko

2014-08-28

It is well known that electromagnetic phenomena are often observed preceding earthquakes. However, the mechanism by which these electromagnetic waves are generated during the fracture and deformation of rocks has not been fully identified. Therefore, in order to examine the relationship between the electromagnetic phenomena and the mechanical properties of rocks, uniaxial compression and three-point bending tests for two kinds of rocks with different quartz content, granite and gabbro, have been carried out at quasi-static and dynamic rates. Especially, in the bending tests, pre-cracked specimens of granite were also tested. Using a split Hopkinson pressure bar and a ferrite-core antenna in close proximity to the specimens, both the stress-strain (load-displacement) curve and simultaneous electromagnetic wave magnitude were measured. It was found that the dynamic compressive and bending strengths and the stress increase slope of both rocks were higher than those observed in static tests; therefore, there is a strain-rate dependence in their strength and stress increase rate. It was found from the tests using the pre-cracked bending specimens that the intensity of electromagnetic waves measured during crack extension increased almost proportionally to the increase of the maximum stress intensity factor of specimens. This tendency was observed in both the dynamic and quasi-static three-point bending tests for granite. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

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.

Possible Mechanism of Action of the Electromagnetic Fields of Ultralow Frequency on G-protein

NASA Astrophysics Data System (ADS)

Nava, J. J. Godina; Segura, M. A. Rodríguez; García, M. N. Jiménez; Cadena, M. S. Reyes

2008-08-01

Based in several clinical achievements and mathematical simulation of the immune sytem, previously studied, permit us to establish that a possible Mechanism of Action of ultralow frequency Electromagnetic Fields (ELF) is on G-protein as it has been proposed in specialized literature.

Monitoring relative humidity in RPC detectors by use of fiber optic sensors

NASA Astrophysics Data System (ADS)

Caponero, M. A.; Polimadei, A.; Benussi, L.; Bianco, S.; Colafranceschi, S.; Passamonti, L.; Piccolo, D.; Pierluigi, D.; Russo, A.; Felli, F.; Saviano, G.; Vendittozzi, C.

2013-03-01

We propose to adopt Fiber Bragg Grating technology to develop an innovative sensor for monitoring relative humidity of the gas fluxed in Resistive Plate Counters. Use of Fiber Bragg Grating as sensing device makes the proposed sensor well suited to develop distributed real-time monitoring systems to be installed on large volume detectors operated in high electromagnetic fields. In fact Fiber Bragg Gratings are fully immune from electromagnetic disturbances and allow simplified wiring by in-series interconnection of tens of them along a single optical fiber. In this paper we present results intended to investigate the feasibility of our proposal.

Poynting Theorem, Relativistic Transformation of Total Energy-Momentum and Electromagnetic Energy-Momentum Tensor

NASA Astrophysics Data System (ADS)

Kholmetskii, Alexander; Missevitch, Oleg; Yarman, Tolga

2016-02-01

We address to the Poynting theorem for the bound (velocity-dependent) electromagnetic field, and demonstrate that the standard expressions for the electromagnetic energy flux and related field momentum, in general, come into the contradiction with the relativistic transformation of four-vector of total energy-momentum. We show that this inconsistency stems from the incorrect application of Poynting theorem to a system of discrete point-like charges, when the terms of self-interaction in the product {\\varvec{j}} \\cdot {\\varvec{E}} (where the current density {\\varvec{j}} and bound electric field {\\varvec{E}} are generated by the same source charge) are exogenously omitted. Implementing a transformation of the Poynting theorem to the form, where the terms of self-interaction are eliminated via Maxwell equations and vector calculus in a mathematically rigorous way (Kholmetskii et al., Phys Scr 83:055406, 2011), we obtained a novel expression for field momentum, which is fully compatible with the Lorentz transformation for total energy-momentum. The results obtained are discussed along with the novel expression for the electromagnetic energy-momentum tensor.

Electromagnetic Thermography Nondestructive Evaluation: Physics-based Modeling and Pattern Mining

PubMed Central

Gao, Bin; Woo, Wai Lok; Tian, Gui Yun

2016-01-01

Electromagnetic mechanism of Joule heating and thermal conduction on conductive material characterization broadens their scope for implementation in real thermography based Nondestructive testing and evaluation (NDT&E) systems by imparting sensitivity, conformability and allowing fast and imaging detection, which is necessary for efficiency. The issue of automatic material evaluation has not been fully addressed by researchers and it marks a crucial first step to analyzing the structural health of the material, which in turn sheds light on understanding the production of the defects mechanisms. In this study, we bridge the gap between the physics world and mathematical modeling world. We generate physics-mathematical modeling and mining route in the spatial-, time-, frequency-, and sparse-pattern domains. This is a significant step towards realizing the deeper insight in electromagnetic thermography (EMT) and automatic defect identification. This renders the EMT a promising candidate for the highly efficient and yet flexible NDT&E. PMID:27158061

Shaping metallic glasses by electromagnetic pulsing

PubMed Central

Kaltenboeck, Georg; Demetriou, Marios D.; Roberts, Scott; Johnson, William L.

2016-01-01

With damage tolerance rivalling advanced engineering alloys and thermoplastic forming capabilities analogous to conventional plastics, metallic glasses are emerging as a modern engineering material. Here, we take advantage of their unique electrical and rheological properties along with the classic Lorentz force concept to demonstrate that electromagnetic coupling of electric current and a magnetic field can thermoplastically shape a metallic glass without conventional heating sources or applied mechanical forces. Specifically, we identify a process window where application of an electric current pulse in the presence of a normally directed magnetic field can ohmically heat a metallic glass to a softened state, while simultaneously inducing a large enough magnetic body force to plastically shape it. The heating and shaping is performed on millisecond timescales, effectively bypassing crystallization producing fully amorphous-shaped parts. This electromagnetic forming approach lays the groundwork for a versatile, time- and energy-efficient manufacturing platform for ultrastrong metals. PMID:26853460

Energy Flow Exciting Field-Aligned Current at Substorm Expansion Onset

NASA Astrophysics Data System (ADS)

Ebihara, Y.; Tanaka, T.

2017-12-01

At substorm expansion onset, upward field-aligned currents (FACs) increase abruptly, and a large amount of electromagnetic energy starts to consume in the polar ionosphere. A question arises as to where the energy comes from. Based on the results obtained by the global magnetohydrodynamics simulation, we present energy flow and energy conversion associated with the upward FACs that manifest the onset. Our simulations show that the cusp/mantle region transmits electromagnetic energy to almost the entire region of the magnetosphere when the interplanetary magnetic field is southward. Integral curve of the Poynting flux shows a spiral moving toward the ionosphere, probably suggesting the pathway of electromagnetic energy from the cusp/mantle dynamo to the ionosphere. The near-Earth reconnection initiates three-dimensional redistribution of the magnetosphere. Flow shear in the near-Earth region results in the generation of the near-Earth dynamo and the onset FACs. The onset FACs are responsible to transport the electromagnetic energy toward the Earth. In the near-Earth region, the electromagnetic energy coming from the cusp/mantle dynamo is converted to the kinetic energy (known as bursty bulk flow) and the thermal energy (associated with high-pressure region in the inner magnetosphere). Then, they are converted to the electromagnetic energy associated with the onset FACs. A part of electromagnetic energy is stored in the lobe region during the growth phase. The release of the stored energy, together with the continuously supplied energy from the cusp/mantle dynamo, contributes to the energy supply to the ionosphere during the expansion phase.

An automatic target recognition system based on SAR image

NASA Astrophysics Data System (ADS)

Li, Qinfu; Wang, Jinquan; Zhao, Bo; Luo, Furen; Xu, Xiaojian

2009-10-01

In this paper, an automatic target recognition (ATR) system based on synthetic aperture radar (SAR) is proposed. This ATR system can play an important role in the simulation of up-to-data battlefield environment and be used in ATR research. To establish an integral and available system, the processing of SAR image was divided into four main stages which are de-noise, detection, cluster-discrimination and segment-recognition, respectively. The first three stages are used for searching region of interest (ROI). Once the ROIs are extracted, the recognition stage will be taken to compute the similarity between the ROIs and the templates in the electromagnetic simulation software National Electromagnetic Scattering Code (NESC). Due to the lack of the SAR raw data, the electromagnetic simulated images are added to the measured SAR background to simulate the battlefield environment8. The purpose of the system is to find the ROIs which can be the artificial military targets such as tanks, armored cars and so on and to categorize the ROIs into the right classes according to the existing templates. From the results we can see that the proposed system achieves a satisfactory result.

Electromagnetic tornadoes in space. Ion conics along auroral field lines generated by lower hybrid waves and electromagnetic turbulence in the ion-cyclotron range of frequencies

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

Chang, T.; Crew, G.B.; Retterer, J.M.

1988-01-01

The exotic phenomenon of energetic ion-conic formation by plasma waves in the magnetosphere is considered. Two particular transverse heating mechanisms are reviewed in detail: lower-hybrid energization of ions in the boundary layer of the plasma sheet, and electromagnetic ion cyclotron resonance heating in the central region of the plasma sheet. Mean particle calculations, plasma simulations, and analytical treatments of the heating processes are described.

Project MANTIS: A MANTle Induction Simulator for coupling geodynamic and electromagnetic modeling

NASA Astrophysics Data System (ADS)

Weiss, C. J.

2009-12-01

A key component to testing geodynamic hypotheses resulting from the 3D mantle convection simulations is the ability to easily translate the predicted physiochemical state to the model space relevant for an independent geophysical observation, such as earth's seismic, geodetic or electromagnetic response. In this contribution a new parallel code for simulating low-frequency, global-scale electromagnetic induction phenomena is introduced that has the same Earth discretization as the popular CitcomS mantle convection code. Hence, projection of the CitcomS model into the model space of electrical conductivity is greatly simplified, and focuses solely on the node-to-node, physics-based relationship between these Earth parameters without the need for "upscaling", "downscaling", averaging or harmonizing with some other model basis such as spherical harmonics. Preliminary performance tests of the MANTIS code on shared and distributed memory parallel compute platforms shows favorable scaling (>70% efficiency) for up to 500 processors. As with CitcomS, an OpenDX visualization widget (VISMAN) is also provided for 3D rendering and interactive interrogation of model results. Details of the MANTIS code will be briefly discussed here, focusing on compatibility with CitcomS modeling, as will be preliminary results in which the electromagnetic response of a CitcomS model is evaluated. VISMAN rendering of electrical tomography-derived electrical conductivity model overlain by an a 1x1 deg crustal conductivity map. Grey scale represents the log_10 magnitude of conductivity [S/m]. Arrows are horiztonal components of a hypothetical magnetospheric source field used to electromagnetically excite the conductivity model.

Simulation of electrical and thermal fields in a multimode microwave oven using software written in C++

NASA Astrophysics Data System (ADS)

Abrudean, C.

2017-05-01

Due to multiple reflexions on walls, the electromagnetic field in a multimode microwave oven is difficult to estimate analytically. This paper presents a C++ program that calculates the electromagnetic field in a resonating cavity with an absorbing payload, uses the result to calculate heating in the payload taking its properties into account and then repeats. This results in a simulation of microwave heating, including phenomena like thermal runaway. The program is multithreaded to make use of today’s common multiprocessor/multicore computers.

Consumer Electronics Testing to Fast-Rise EMP (Electromagnetic Pulse) (VEMPS (Vertical Electromagnetic Pulse Simulator) 2 Development)

DTIC Science & Technology

1989-06-01

Fast-Rise EMP ( VEMPS 11 Development) 12. PERSONAL AUTHOR(S) Vincent J. Ellis 13a. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year Mot.Dy...SUBJECT TERMS (Continue on reverse if necessary andJ identity by block nwitib") 09EL 03U SBGR EMP, VEMPS 11, consumer electronics, FEMPS, EMP simulation... VEMPS 11), Because of the unique petrr! ance characteristics of VEMPS 11 and the technological changes In consumer electronics over the past 10 years

Numerical simulation of compact intracloud discharge and generated electromagnetic pulse

NASA Astrophysics Data System (ADS)

Babich, L. P.; Bochkov, E. I.; Kutsyk, I. M.

2015-06-01

Using the concept of the relativistic runaway electron avalanche, numerical simulation of compact intracloud discharge as a generator of powerful natural electromagnetic pulses (EMPs) in the HF-UHF range was conducted. We evaluated the numbers of electrons initiating the avalanche, with which the calculated EMP characteristics are consistent with measured ones. The discharge capable of generating EMPs produces runaway electrons in numbers close to those in the source of terrestrial γ-flashes (TGF) registered in the nearest space, which may be an argument for a joint EMP and TGF source.

Interactive electromagnetic launcher simulation

NASA Astrophysics Data System (ADS)

Young, F. J.; Howland, H. R.; Hughes, W. F.; Fikse, D. A.

1982-01-01

The mathematical model, usage, and documentation of an interactive computer simulation for an electromagnetic launcher is presented. The launcher is modeled as an electrical circuit. Three slight variations of the program permit studies of a launcher with (1) rail skin effects, (2) rail skin effects and approximated storage coil skin effects, or (3) neither of these effects. Usage of the program as currently implemented on the Westinghouse R&D Univac 1106 is described, with a sample session shown. The implementation of the program permits rapid scoping of the effects of parameter changes.

Understanding and manipulating the RF fields at high field MRI

PubMed Central

Ibrahim, Tamer S.; Hue, YiK-Kiong; Tang, Lin

2015-01-01

This paper presents a complete overview of the electromagnetics (radiofrequency aspect) of MRI at low and high fields. Using analytical formulations, numerical modeling (computational electromagnetics), and ultrahigh field imaging experiments, the physics that impacts the electromagnetic quantities associated with MRI, namely (1) the transmit field, (2) receive field, and (3) total electromagnetic power absorption, is analyzed. The physical interpretation of the above-mentioned quantities is investigated by electromagnetic theory, to understand ‘What happens, in terms of electromagnetics, when operating at different static field strengths?’ Using experimental studies and numerical simulations, this paper also examines the physical and technological feasibilities by which all or any of these specified electromagnetic quantities can be manipulated through techniques such as B1 shimming (phased array excitation) and signal combination using a receive array in order to advance MRI at high field strengths. Pertinent to this subject and with highly coupled coils operating at 7 T, this paper also presents the first phantom work on B1 shimming without B1 measurements. PMID:19621335

Proceedings of the Eleventh International Conference on Calorimetry in Particle Physics

NASA Astrophysics Data System (ADS)

Cecchi, Claudia

The Pamela silicon tungsten calorimeter / G. Zampa -- Design and development of a dense, fine grained silicon tungsten calorimeter with integrated electronics / D. Strom -- High resolution silicon detector for 1.2-3.1 eV (400-1000 nm) photons / D. Groom -- The KLEM high energy cosmic rays collector for the NUCLEON satellite mission / M. Merkin (contribution not received) -- The electromagnetic calorimeter of the Hera-b experiment / I. Matchikhilian -- The status of the ATLAS tile calorimeter / J. Mendes Saraiva -- Design and mass production of Scintillator Pad Detector (SPD) / Preshower (PS) detector for LHC-b experiment / E. Gushchin -- Study of new FNAL-NICADD extruded scintillator as active media of large EMCal of ALICE at LHC / O. Grachov -- The CMS hadron calorimeter / D. Karmgard (contribution not received) -- Test beam study of the KOPIO Shashlyk calorimeter prototype / A. Poblaguev -- The Shashlik electro-magnetic calorimeter for the LHCb experiment / S. Barsuk -- Quality of mass produced lead-tungstate crystals / R. Zhu -- Status of the CMS electromagnetic calorimeter / J. Fay -- Scintillation detectors for radiation-hard electromagnetic calorimeters / H. Loehner -- Energy, timing and two-photon invariant mass resolution of a 256-channel PBWO[symbol] calorimeter / M. Ippolitov -- A high performance hybrid electromagnetic calorimeter at Jefferson Lab / A. Gasparian -- CsI(Tl) calorimetry on BESHI / T. Hu (contribution not received) -- The crystal ball and TAPS detectors at the MAMI electron beam facility / D. Watts -- Front-end electronics of the ATLAS tile calorimeter / R. Teuscher -- The ATLAS tilecal detector control system / A. Gomes -- Performance of the liquid argon final calibration board / C. de la Taille -- Overview of the LHCb calorimeter electronics / F. Machefert -- LHCb preshower photodetector and electronics / S. Monteil -- The CMS ECAL readout architecture and the clock and control system / K. Kloukinas -- Test of the CMS-ECAL trigger primitive generation / N. Regnault -- Optical data links for the CMS ECAL / J. Grahl (contribution not received) -- CMS ECAL off-detector electronics / R. Alemany Fernandez -- Performance of a low noise readout ASIC for the W-Si calorimeter physics prototype for the future linear collider / C. de la Taille -- Properties of a sampling calorimeter with warm-liquid ionization chambers / S. Plewnia -- Calorimetry and the DO experiment / R. Zitoun (contribution not received) -- Data quality monitoring for the DØ calorimeter / V. Shary -- Status of the construction of the ATLAS electromagnetic liquid argon calorimeter, overview of beam test performance studies / L. Serin -- Uniformity of response of ATLAS liquid argon EM calorimeter / O. Gaunter -- Status of the ATLAS liquid argon hadronic endcap calorimeter construction / M. Vincter -- Results from particle beam tests of the ATLAS liquid argon endcap calorimeters / M. Lefebvre -- First results of the DREAM project / R. Wigmans -- Electron and muon detection with a dual-readout (DREAM) calorimeter / N. Akchurin -- The neutron zero degree calorimeter for the ALICE experiment / M. Gallio -- The liquid xenon scintillation calorimeter of the MEG experiment: operation of a large prototype / G. Signorelli -- Detection of high energy particles using radio frequency signals / C. Hebert -- Hadronic shower simulation / J.-P. Wellisch -- E.M. and hadronic shower simulation with FLUKA / G. Battistoni -- Simulation of the LHCb electromagnetic calorimeter response with GEANT4 / P. Robbe -- Comparison of beam test results of the combined ATLAS liquid argon endcap calorimeters with GEANT3 and GEANT4 simulations / D. Salihagić -- GEANT4 hadronic physics validation with LHC test-beam data / C. Alexa -- The full simulation of the GLAST LAT high energy gamma ray telescope / F. Longo -- Response of the KLOE electromagnetic calorimeter to low-energy particles / T. Spadaro -- Calorimeter algorithms for DØ; / S. Trincaz-Duvoid -- Identification of low P[symbol] muon with the ATLAS tile calorimeter / G. Usai -- Electron and photon reconstruction with fully simulated events in the CMS experiment / G. Daskalakis -- Expected performance of Jet, [symbol] and [symbol] reconstruction in ATLAS / I. Vivarelli -- LHCb calorimeter from trigger to physics / O. Deschamps -- The calibration strategy of CMS electromagnetic calorimeter / P. Meridiani -- Energy and impact point reconstruction in the CMS ECAL (testbeam results from 2003) / I. B. van Vulpen -- The jet energy scale and resolution in the DO calorimeter / A. Kupco (contribution not received) -- Precision linearity studies of the ATLAS liquid argon EM calorimeter / G. Graziani -- Calibration of the ATLAS tile calorimeter / F. Sarri -- Performance of the CMS ECAL laser monitoring source in the test beam / A. Bornheim -- Energy reconstruction algorithms and their influence on the ATLAS tile calorimeter / E. Fullana -- Study of the biological effectiveness of ionizing radiations for a more realistic evaluation of the radiation quality in hadrontherapy / R. Cherubini (contribution not received) -- New dosimetry technologies for IMRT (Intensity Modulated Radio Therapy) / A. Piermattei -- Photon neutron radiotherapy / G. Giannini (contribution not received) -- Recent developments in molecular imaging / G. Zavattini (contribution not received) -- Performance goals and design considerations for a linear collider calorimeter / F. Sefkow -- Improving the jet reconstruction with the particle flow method; an introduction / J.-C. Brient -- Fine grained SiW ECAL for a linear collider detector / D. Strom (in the silicon session) -- Silicon-tungsten sampling electromagnetic calorimeter for the TeV electron-positron linear collider / J.-C. Brient -- LCCAL: a calorimeter prototype for future linear colliders / S. Miscetti -- Analog vs digital hadron calorimetry at a future electron-positron linear collider / S. Magill -- Toward a scintillator based heal and tail catcher for the LC calorimeter / M. Martin (contribution not received) -- Minical options, description in MC, calibration, plans for test beam prototype / G. Eigen (contribution not received) -- Photodetector options for a scintillator heal / E. Popova (contribution not received) -- Very low background scintillators in DAMA project: results and perspectives / R. Bernabei -- EDELWEISS Ge cryogenics detectors: main performance and physics results / X. Navick (contribution not received) -- Review of massive underground detectors / A. Rubbia -- Review of neutrino telescopes underwater and under ice / A. Capone (contribution not received) -- The fluorescence detector of the Pierre Auger Observatory / R. Caruso -- The EUSO mission for the observation of ultra high energy cosmic rays from space / A. Petrolini -- Performance of a 3D imaging electromagnetic calorimeter for the AMSO2 space experiment / C. Adloff -- Beam test calibration of the balloon borne imaging calorimeter for the CREAM experiment / P. Maestro.

Electromagnetic radiation from beam-plasma instabilities

NASA Technical Reports Server (NTRS)

Pritchett, P. L.; Dawson, J. M.

1983-01-01

A computer simulation is developed for the generation of electromagnetic radiation in an electron beam-plasma interaction. The plasma is treated as a two-dimensional finite system, and effects of a continuous nonrelativistic beam input are accounted for. Three momentum and three field components are included in the simulation, and an external magnetic field is excluded. EM radiation generation is possible through interaction among Langmuir oscillations, ion-acoustic waves, and the electromagnetic wave, producing radiation perpendicular to the beam. The radiation is located near the plasma frequency, and polarized with the E component parallel to the beam. The scattering of Langmuir waves caused by ion-acoustic fluctuations generates the radiation. Comparison with laboratory data for the three-wave interactions shows good agreement in terms of the radiation levels produced, which are small relative to the plasma thermal energy.

Low temperature deformation behavior of an electromagnetically bulged 5052 aluminum alloy

PubMed Central

Li, Zu; Li, Ning; Wang, Duzhen; Ouyang, Di; Liu, Lin

2016-01-01

The fundamental understanding of the deformation behavior of electromagnetically formed metallic components under extreme conditions is important. Here, the effect of low temperature on the deformation behavior of an electromagnetically-bulged 5052 aluminum alloy was investigated through uniaxial tension. We found that the Portevin-Le Chatelier Effect, designated by the serrated characteristic in stress-strain curves, continuously decays until completely disappears with decreasing temperature. The physical origin of the phenomenon is rationalized on the basis of the theoretical analysis and the Monte Carlo simulation, which reveal an increasing resistance to dislocation motion imposed by lowering temperature. The dislocations are captured completely by solute atoms at −50 °C, which results in the extinction of Portevin-Le Chatelier. The detailed mechanism responsible for this process is further examined through Monte Carlo simulation. PMID:27426919

Copper Tube Compression in Z-Current Geometry, Numerical Simulations and Comparison with Cyclope Experiments

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

Lefrancois, A.; L'Eplattenier, P.; Burger, M.

2006-02-13

Metallic tubes compressions in Z-current geometry were performed at the Cyclope facility from Gramat Research Center in order to study the behavior of metals under large strain at high strain rate. 3D configurations of cylinder compressions have been calculated here to benchmark the new beta version of the electromagnetism package coupled with the dynamics in Ls-Dyna and compared with the Cyclope experiments. The electromagnetism module is being developed in the general-purpose explicit and implicit finite element program LS-DYNA{reg_sign} in order to perform coupled mechanical/thermal/electromagnetism simulations. The Maxwell equations are solved using a Finite Element Method (FEM) for the solid conductorsmore » coupled with a Boundary Element Method (BEM) for the surrounding air (or vacuum). More details can be read in the references.« less

Kinetic simulations of X-B and O-X-B mode conversion and its deterioration at high input power

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

Arefiev, A. V.; Dodin, I. Y.; Kohn, A.

Spherical tokamak plasmas are typically overdense and thus inaccessible to externally-injected microwaves in the electron cyclotron range. The electrostatic electron Bernstein wave (EBW), however, provides a method to access the plasma core for heating and diagnostic purposes. Understanding the details of the coupling process to electromagnetic waves is thus important both for the interpretation of microwave diagnostic data and for assessing the feasibility of EBW heating and current drive. While the coupling is reasonably well–understood in the linear regime, nonlinear physics arising from high input power has not been previously quantified. To tackle this problem, we have performed one- andmore » two-dimensional fully kinetic particle-in-cell simulations of the two possible coupling mechanisms, namely X-B and O-X-B mode conversion. We find that the ion dynamics has a profound effect on the field structure in the nonlinear regime, as high amplitude short-scale oscillations of the longitudinal electric field are excited in the region below the high-density cut-off prior to the arrival of the EBW. We identify this effect as the instability of the X wave with respect to resonant scattering into an EBW and a lower-hybrid wave. Finally, we calculate the instability rate analytically and find this basic theory to be in reasonable agreement with our simulation results.« less

Characteristics of temporal evolution of particle density and electron temperature in helicon discharge

NASA Astrophysics Data System (ADS)

Yang, Xiong; Cheng, Mousen; Guo, Dawei; Wang, Moge; Li, Xiaokang

2017-10-01

On the basis of considering electrochemical reactions and collision relations in detail, a direct numerical simulation model of a helicon plasma discharge with three-dimensional two-fluid equations was employed to study the characteristics of the temporal evolution of particle density and electron temperature. With the assumption of weak ionization, the Maxwell equations coupled with the plasma parameters were directly solved in the whole computational domain. All of the partial differential equations were solved by the finite element solver in COMSOL MultiphysicsTM with a fully coupled method. In this work, the numerical cases were calculated with an Ar working medium and a Shoji-type antenna. The numerical results indicate that there exist two distinct modes of temporal evolution of the electron and ground atom density, which can be explained by the ion pumping effect. The evolution of the electron temperature is controlled by two schemes: electromagnetic wave heating and particle collision cooling. The high RF power results in a high peak electron temperature while the high gas pressure leads to a low steady temperature. In addition, an OES experiment using nine Ar I lines was conducted using a modified CR model to verify the validity of the results by simulation, showing that the trends of temporal evolution of electron density and temperature are well consistent with the numerically simulated ones.

Kinetic simulations of X-B and O-X-B mode conversion and its deterioration at high input power

DOE PAGES

Arefiev, A. V.; Dodin, I. Y.; Kohn, A.; ...

2017-08-09

Spherical tokamak plasmas are typically overdense and thus inaccessible to externally-injected microwaves in the electron cyclotron range. The electrostatic electron Bernstein wave (EBW), however, provides a method to access the plasma core for heating and diagnostic purposes. Understanding the details of the coupling process to electromagnetic waves is thus important both for the interpretation of microwave diagnostic data and for assessing the feasibility of EBW heating and current drive. While the coupling is reasonably well–understood in the linear regime, nonlinear physics arising from high input power has not been previously quantified. To tackle this problem, we have performed one- andmore » two-dimensional fully kinetic particle-in-cell simulations of the two possible coupling mechanisms, namely X-B and O-X-B mode conversion. We find that the ion dynamics has a profound effect on the field structure in the nonlinear regime, as high amplitude short-scale oscillations of the longitudinal electric field are excited in the region below the high-density cut-off prior to the arrival of the EBW. We identify this effect as the instability of the X wave with respect to resonant scattering into an EBW and a lower-hybrid wave. Finally, we calculate the instability rate analytically and find this basic theory to be in reasonable agreement with our simulation results.« less

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

Endres, Michael G.; Shindler, Andrea; Tiburzi, Brian C.

The commonly adopted approach for including electromagnetic interactions in lattice QCD simulations relies on using finite volume as the infrared regularization for QED. The long-range nature of the electromagnetic interaction, however, implies that physical quantities are susceptible to power-law finite volume corrections, which must be removed by performing costly simulations at multiple lattice volumes, followed by an extrapolation to the infinite volume limit. In this work, we introduce a photon mass as an alternative means for gaining control over infrared effects associated with electromagnetic interactions. We present findings for hadron mass shifts due to electromagnetic interactions (i.e., for the proton,more » neutron, charged and neutral kaon) and corresponding mass splittings, and compare the results with those obtained from conventional QCD+QED calculations. Results are reported for numerical studies of three flavor electroquenched QCD using ensembles corresponding to 800 MeV pions, ensuring that the only appreciable volume corrections arise from QED effects. The calculations are performed with three lattice volumes with spatial extents ranging from 3.4 - 6.7 fm. As a result, we find that for equal computing time (not including the generation of the lattice configurations), the electromagnetic mass shifts can be extracted from computations on a single (our smallest) lattice volume with comparable or better precision than the conventional approach.« less

Massive photons: An infrared regularization scheme for lattice QCD + QED

DOE PAGES

Endres, Michael G.; Shindler, Andrea; Tiburzi, Brian C.; ...

2016-08-10

The commonly adopted approach for including electromagnetic interactions in lattice QCD simulations relies on using finite volume as the infrared regularization for QED. The long-range nature of the electromagnetic interaction, however, implies that physical quantities are susceptible to power-law finite volume corrections, which must be removed by performing costly simulations at multiple lattice volumes, followed by an extrapolation to the infinite volume limit. In this work, we introduce a photon mass as an alternative means for gaining control over infrared effects associated with electromagnetic interactions. We present findings for hadron mass shifts due to electromagnetic interactions (i.e., for the proton,more » neutron, charged and neutral kaon) and corresponding mass splittings, and compare the results with those obtained from conventional QCD+QED calculations. Results are reported for numerical studies of three flavor electroquenched QCD using ensembles corresponding to 800 MeV pions, ensuring that the only appreciable volume corrections arise from QED effects. The calculations are performed with three lattice volumes with spatial extents ranging from 3.4 - 6.7 fm. As a result, we find that for equal computing time (not including the generation of the lattice configurations), the electromagnetic mass shifts can be extracted from computations on a single (our smallest) lattice volume with comparable or better precision than the conventional approach.« less

Generation of ordinary mode electromagnetic radiation near the upper hybrid frequency in the magnetosphere

NASA Technical Reports Server (NTRS)

Ashour-Abdalla, M.; Okuda, H.

1984-01-01

It is shown by means of plasma numerical simulations that long-wavelength ordinary mode electromagnetic radiation can be generated from short-wavelength electrostatic waves near the upper hybrid resonance frequency in an inhomogeneous plasma. A possible relation of this process to nonthermal continuum radiation in the magnetosphere is discussed.

Learning Physics with Digital Game Simulations in Middle School Science

ERIC Educational Resources Information Center

Anderson, Janice L.; Barnett, Mike

2013-01-01

The purpose of this work is to share our findings in using video gaming technology to facilitate the understanding of basic electromagnetism with middle school students. To this end, we explored the impact of using a game called "Supercharged!" on middle school students' understanding of electromagnetic concepts compared to students…

The Use of Computer-Simulated Trajectories to Teach Real Particle Flight

ERIC Educational Resources Information Center

Gagnon, Michel

2011-01-01

The close relationship between charged particles and electromagnetic fields has been well known since the 19th century, thanks to James Clerk Maxwell's brilliant unified theory of electricity and magnetism. Today, electromagnetism is recognized as an essential aspect of human activity and has consequently become a major component of senior…

Influence of surface error on electromagnetic performance of reflectors based on Zernike polynomials

NASA Astrophysics Data System (ADS)

Li, Tuanjie; Shi, Jiachen; Tang, Yaqiong

2018-04-01

This paper investigates the influence of surface error distribution on the electromagnetic performance of antennas. The normalized Zernike polynomials are used to describe a smooth and continuous deformation surface. Based on the geometrical optics and piecewise linear fitting method, the electrical performance of reflector described by the Zernike polynomials is derived to reveal the relationship between surface error distribution and electromagnetic performance. Then the relation database between surface figure and electric performance is built for ideal and deformed surfaces to realize rapidly calculation of far-field electric performances. The simulation analysis of the influence of Zernike polynomials on the electrical properties for the axis-symmetrical reflector with the axial mode helical antenna as feed is further conducted to verify the correctness of the proposed method. Finally, the influence rules of surface error distribution on electromagnetic performance are summarized. The simulation results show that some terms of Zernike polynomials may decrease the amplitude of main lobe of antenna pattern, and some may reduce the pointing accuracy. This work extracts a new concept for reflector's shape adjustment in manufacturing process.

A field test of electromagnetic geophysical techniques for locating simulated in situ mining leach solution

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

Tweeton, D.R.; Hanson, J.C.; Friedel, M.J.

1994-01-01

The US Bureau of Mines, The University of Arizona, Sandia National Laboratories, and Zonge Engineering and Research Organization, Inc., conducted cooperative field tests of six electromagnetic (EM) geophysical methods to compare their effectiveness in locating a brine solution simulating in situ leach solution or a high-conductivity plume of contamination. The brine was approximately 160 m below the surface. The testsite was the University's San Xavier experimental mine near Tucson, AZ. Geophysical surveys using surface and surface-borehole, time-domain electromagnetic (TEM) induction; surface controlled-source audiofrequency magnetotellurics (CSAMT); surface-borehole, frequency-domain electromagnetic (FEM) induction; crosshole FEM; and surface magnetic field ellipticity were conducted beforemore » and during brine injection. The surface TEM data showed a broad decrease in resistivity. CSAMT measurements with the conventional orientation did not detect the brine, but measurements with another orientation indicated some decrease in resistivity. The surface-borehole and crosshole methods located a known fracture and other fracture zones inferred from borehole induction logs. Surface magnetic field ellipticity data showed a broad decrease in resistivity at depth following brine injection.« less

An Electromagnetic/Capacitive Composite Sensor for Testing of Thermal Barrier Coatings

PubMed Central

Ren, Yuan; Pan, Mengchun; Chen, Dixiang; Tian, Wugang

2018-01-01

Thermal barrier coatings (TBCs) can significantly reduce the operating temperature of the aeroengine turbine blade substrate, and their testing technology is very urgently demanded. Due to their complex multi-layer structure, it is hard to evaluate TBCs with a single function sensor. In this paper, an electromagnetic/capacitive composite sensor is proposed for the testing of thermal barrier coatings. The dielectric material is tested with planar capacitor, and the metallic material is tested with electromagnetic coils. Then, the comprehensive test and evaluation of thermal barrier coating system can be realized. The sensor is optimized by means of theoretical and simulation analysis, and the interaction between the planar capacitor and the electromagnetic coil is studied. The experimental system is built based on an impedance analyser and multiplex unit to evaluate the performance of the composite sensor. The transimpedances and capacitances are measured under different coating parameters, such as thickness and permittivity of top coating as well as bond layer conductivity. The experimental results agree with the simulation analysis, and the feasibility of the sensor is proved. PMID:29783746

Controlling of the electromagnetic solitary waves generation in the wake of a two-color laser

NASA Astrophysics Data System (ADS)

Pan, K. Q.; Li, S. W.; Guo, L.; Yang, D.; Li, Z. C.; Zheng, C. Y.; Jiang, S. E.; Zhang, B. H.; He, X. T.

2018-05-01

Electromagnetic solitary waves generated by a two-color laser interaction with an underdense plasma are investigated. It is shown that, when the former wave packet of the two-color laser is intense enough, it will excite nonlinear wakefields and generate electron density cavities. The latter wave packets will beat with the nonlinear wakefield and generate both high-frequency and low-frequency components. When the peak density of the cavities exceeds the critical density of the low-frequency component, this part of the electromagnetic field will be trapped to generate electromagnetic solitary waves. By changing the laser and plasma parameters, we can control the wakefield generation, which will also control the generation of the solitary waves. One-dimensional particle-in-cell simulations are performed to prove the controlling of the solitary waves. The simulation results also show that solitary waves generated by higher laser intensities will become moving solitary waves. The two-dimensional particle-in-cell also shows the generation of the solitary waves. In the two-dimensional case, solitary waves are distributed in the transverse directions because of the filamentation instability.

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

Parity-time-symmetric teleportation

NASA Astrophysics Data System (ADS)

Ra'di, Y.; Sounas, D. L.; Alù, A.; Tretyakov, S. A.

2016-06-01

We show that electromagnetic plane waves can be fully "teleported" through thin, nearly fully reflective sheets, assisted by a pair of parity-time-symmetric lossy and active sheets in front and behind the screen. The proposed structure is able to almost perfectly absorb incident waves over a wide range of frequency and incidence angles, while waves having a specific frequency and incidence angle are replicated behind the structure in synchronization with the input signal. It is shown that the proposed structure can be designed to teleport waves at any desired frequency and incidence angle. Furthermore, we generalize the proposed concept to the case of teleportation of electromagnetic waves over electrically long distances, enabling full absorption at one surface and the synthesis of the same signal at another point located electrically far away from the first surface. The physical principle behind this selective teleportation is discussed, and similarities and differences with tunneling and cloaking concepts based on PT symmetry are investigated. From the application point of view, the proposed structure works as an extremely selective filter, both in frequency and spatial domains.

Center for Extended Magnetohydrodynamics Modeling - Final Technical Report

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

Parker, Scott

This project funding supported approximately 74 percent of a Ph.D. graduate student, not including costs of travel and supplies. We had a highly successful research project including the development of a second-order implicit electromagnetic kinetic ion hybrid model [Cheng 2013, Sturdevant 2016], direct comparisons with the extended MHD NIMROD code and kinetic simulation [Schnack 2013], modeling of slab tearing modes using the fully kinetic ion hybrid model and finally, modeling global tearing modes in cylindrical geometry using gyrokinetic simulation [Chen 2015, Chen 2016]. We developed an electromagnetic second-order implicit kinetic ion fluid electron hybrid model [Cheng 2013]. As a firstmore » step, we assumed isothermal electrons, but have included drift-kinetic electrons in similar models [Chen 2011]. We used this simulation to study the nonlinear evolution of the tearing mode in slab geometry, including nonlinear evolution and saturation [Cheng 2013]. Later, we compared this model directly to extended MHD calculations using the NIMROD code [Schnack 2013]. In this study, we investigated the ion-temperature-gradient instability with an extended MHD code for the first time and got reasonable agreement with the kinetic calculation in terms of linear frequency, growth rate and mode structure. We then extended this model to include orbit averaging and sub-cycling of the ions and compared directly to gyrokinetic theory [Sturdevant 2016]. This work was highlighted in an Invited Talk at the International Conference on the Numerical Simulation of Plasmas in 2015. The orbit averaging sub-cycling multi-scale algorithm is amenable to hybrid architectures with GPUS or math co-processors. Additionally, our participation in the Center for Extend Magnetohydrodynamics motivated our research on developing the capability for gyrokinetic simulation to model a global tearing mode. We did this in cylindrical geometry where the results could be benchmarked with existing eigenmode calculations. First, we developed a gyrokinetic code capable of simulating long wavelengths using a fluid electron model [Chen 2015]. We benchmarked this code with an eigenmode calculation. Besides having to rewrite the field solver due to the breakdown in the gyrokinetic ordering for long wavelengths, very high radial resolution was required. We developed a technique where we used the solution from the eigenmode solver to specify radial boundary conditions allowing for a very high radial resolution of the inner solution. Using this technique enabled us to use our direct algorithm with gyrokinetic ions and drift kinetic electrons [Chen 2016]. This work was highlighted in an Invited Talk at the American Physical Society - Division of Plasma Physics in 2015.« less

Electro-Thermal-Mechanical Simulation Capability Final Report

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

White, D

This is the Final Report for LDRD 04-ERD-086, 'Electro-Thermal-Mechanical Simulation Capability'. The accomplishments are well documented in five peer-reviewed publications and six conference presentations and hence will not be detailed here. The purpose of this LDRD was to research and develop numerical algorithms for three-dimensional (3D) Electro-Thermal-Mechanical simulations. LLNL has long been a world leader in the area of computational mechanics, and recently several mechanics codes have become 'multiphysics' codes with the addition of fluid dynamics, heat transfer, and chemistry. However, these multiphysics codes do not incorporate the electromagnetics that is required for a coupled Electro-Thermal-Mechanical (ETM) simulation. There aremore » numerous applications for an ETM simulation capability, such as explosively-driven magnetic flux compressors, electromagnetic launchers, inductive heating and mixing of metals, and MEMS. A robust ETM simulation capability will enable LLNL physicists and engineers to better support current DOE programs, and will prepare LLNL for some very exciting long-term DoD opportunities. We define a coupled Electro-Thermal-Mechanical (ETM) simulation as a simulation that solves, in a self-consistent manner, the equations of electromagnetics (primarily statics and diffusion), heat transfer (primarily conduction), and non-linear mechanics (elastic-plastic deformation, and contact with friction). There is no existing parallel 3D code for simulating ETM systems at LLNL or elsewhere. While there are numerous magnetohydrodynamic codes, these codes are designed for astrophysics, magnetic fusion energy, laser-plasma interaction, etc. and do not attempt to accurately model electromagnetically driven solid mechanics. This project responds to the Engineering R&D Focus Areas of Simulation and Energy Manipulation, and addresses the specific problem of Electro-Thermal-Mechanical simulation for design and analysis of energy manipulation systems such as magnetic flux compression generators and railguns. This project compliments ongoing DNT projects that have an experimental emphasis. Our research efforts have been encapsulated in the Diablo and ALE3D simulation codes. This new ETM capability already has both internal and external users, and has spawned additional research in plasma railgun technology. By developing this capability Engineering has become a world-leader in ETM design, analysis, and simulation. This research has positioned LLNL to be able to compete for new business opportunities with the DoD in the area of railgun design. We currently have a three-year $1.5M project with the Office of Naval Research to apply our ETM simulation capability to railgun bore life issues and we expect to be a key player in the railgun community.« less

Comparing the magnetic resonant coupling radiofrequency stimulation to the traditional approaches: Ex-vivo tissue voltage measurement and electromagnetic simulation analysis

NASA Astrophysics Data System (ADS)

Yeung, Sai Ho; Pradhan, Raunaq; Feng, Xiaohua; Zheng, Yuanjin

2015-09-01

Recently, the design concept of magnetic resonant coupling has been adapted to electromagnetic therapy applications such as non-invasive radiofrequency (RF) stimulation. This technique can significantly increase the electric field radiated from the magnetic coil at the stimulation target, and hence enhancing the current flowing through the nerve, thus enabling stimulation. In this paper, the developed magnetic resonant coupling (MRC) stimulation, magnetic stimulation (MS) and transcutaneous electrical nerve stimulation (TENS) are compared. The differences between the MRC RF stimulation and other techniques are presented in terms of the operating mechanism, ex-vivo tissue voltage measurement and electromagnetic simulation analysis. The ev-vivo tissue voltage measurement experiment is performed on the compared devices based on measuring the voltage induced by electromagnetic induction at the tissue. The focusing effect, E field and voltage induced across the tissue, and the attenuation due to the increase of separation between the coil and the target are analyzed. The electromagnetic stimulation will also be performed to obtain the electric field and magnetic field distribution around the biological medium. The electric field intensity is proportional to the induced current and the magnetic field is corresponding to the electromagnetic induction across the biological medium. The comparison between the MRC RF stimulator and the MS and TENS devices revealed that the MRC RF stimulator has several advantages over the others for the applications of inducing current in the biological medium for stimulation purposes.

Comparing the magnetic resonant coupling radiofrequency stimulation to the traditional approaches: Ex-vivo tissue voltage measurement and electromagnetic simulation analysis

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

Yeung, Sai Ho; Pradhan, Raunaq; Feng, Xiaohua

Recently, the design concept of magnetic resonant coupling has been adapted to electromagnetic therapy applications such as non-invasive radiofrequency (RF) stimulation. This technique can significantly increase the electric field radiated from the magnetic coil at the stimulation target, and hence enhancing the current flowing through the nerve, thus enabling stimulation. In this paper, the developed magnetic resonant coupling (MRC) stimulation, magnetic stimulation (MS) and transcutaneous electrical nerve stimulation (TENS) are compared. The differences between the MRC RF stimulation and other techniques are presented in terms of the operating mechanism, ex-vivo tissue voltage measurement and electromagnetic simulation analysis. The ev-vivo tissuemore » voltage measurement experiment is performed on the compared devices based on measuring the voltage induced by electromagnetic induction at the tissue. The focusing effect, E field and voltage induced across the tissue, and the attenuation due to the increase of separation between the coil and the target are analyzed. The electromagnetic stimulation will also be performed to obtain the electric field and magnetic field distribution around the biological medium. The electric field intensity is proportional to the induced current and the magnetic field is corresponding to the electromagnetic induction across the biological medium. The comparison between the MRC RF stimulator and the MS and TENS devices revealed that the MRC RF stimulator has several advantages over the others for the applications of inducing current in the biological medium for stimulation purposes.« less

Investigation of maximum local specific absorption rate in 7 T magnetic resonance with respect to load size by use of electromagnetic simulations.

PubMed

Tiberi, Gianluigi; Fontana, Nunzia; Costagli, Mauro; Stara, Riccardo; Biagi, Laura; Symms, Mark Roger; Monorchio, Agostino; Retico, Alessandra; Cosottini, Mirco; Tosetti, Michela

2015-07-01

Local specific absorption rate (SAR) evaluation in ultra high field (UHF) magnetic resonance (MR) systems is a major concern. In fact, at UHF, radiofrequency (RF) field inhomogeneity generates hot-spots that could cause localized tissue heating. Unfortunately, local SAR measurements are not available in present MR systems; thus, electromagnetic simulations must be performed for RF fields and SAR analysis. In this study, we used three-dimensional full-wave numerical electromagnetic simulations to investigate the dependence of local SAR at 7.0 T with respect to subject size in two different scenarios: surface coil loaded by adult and child calves and quadrature volume coil loaded by adult and child heads. In the surface coil scenario, maximum local SAR decreased with decreasing load size, provided that the RF magnetic fields for the different load sizes were scaled to achieve the same slice average value. On the contrary, in the volume coil scenario, maximum local SAR was up to 15% higher in children than in adults. © 2015 Wiley Periodicals, Inc.

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

Sirunyan, A. M.; Tumasyan, A.; Adam, W.

The CMS apparatus was identified, a few years before the start of the LHC operation at CERN, to feature properties well suited to particle-flow (PF) reconstruction: a highly-segmented tracker, a fine-grained electromagnetic calorimeter, a hermetic hadron calorimeter, a strong magnetic field, and an excellent muon spectrometer. A fully-fledged PF reconstruction algorithm tuned to the CMS detector was therefore developed and has been consistently used in physics analyses for the first time at a hadron collider. For each collision, the comprehensive list of final-state particles identified and reconstructed by the algorithm provides a global event description that leads to unprecedented CMSmore » performance for jet and hadronic tau decay reconstruction, missing transverse momentum determination, and electron and muon identification. This approach also allows particles from pileup interactions to be identified and enables efficient pileup mitigation methods. In conclusion, the data collected by CMS at a centre-of-mass energy of 8 TeV show excellent agreement with the simulation and confirm the superior PF performance at least up to an average of 20 pileup interactions.« less

Two dimensional model for coherent synchrotron radiation

NASA Astrophysics Data System (ADS)

Huang, Chengkun; Kwan, Thomas J. T.; Carlsten, Bruce E.

2013-01-01

Understanding coherent synchrotron radiation (CSR) effects in a bunch compressor requires an accurate model accounting for the realistic beam shape and parameters. We extend the well-known 1D CSR analytic model into two dimensions and develop a simple numerical model based on the Liénard-Wiechert formula for the CSR field of a coasting beam. This CSR numerical model includes the 2D spatial dependence of the field in the bending plane and is accurate for arbitrary beam energy. It also removes the singularity in the space charge field calculation present in a 1D model. Good agreement is obtained with 1D CSR analytic result for free electron laser (FEL) related beam parameters but it can also give a more accurate result for low-energy/large spot size beams and off-axis/transient fields. This 2D CSR model can be used for understanding the limitation of various 1D models and for benchmarking fully electromagnetic multidimensional particle-in-cell simulations for self-consistent CSR modeling.

Excitation of Plasma Waves in Aurora by Electron Beams

NASA Technical Reports Server (NTRS)

daSilva, C. E.; Vinas, A. F.; deAssis, A. S.; deAzevedo, C. A.

1996-01-01

In this paper, we study numerically the excitation of plasma waves by electron beams, in the auroral region above 2000 km of altitude. We have solved the fully kinetic dispersion relation, using numerical method and found the real frequency and the growth rate of the plasma wave modes. We have examined the instability properties of low-frequency waves such as the Electromagnetic Ion Cyclotron (EMIC) wave as well as Lower-Hybrid (LH) wave in the range of high-frequency. In all cases, the source of free energy are electron beams propagating parallel to the geomagnetic field. We present some features of the growth rate modes, when the cold plasma parameters are changed, such as background electrons and ions species (H(+) and O(+)) temperature, density or the electron beam density and/or drift velocity. These results can be used in a test-particle simulation code, to investigate the ion acceleration and their implication in the auroral acceleration processes, by wave-particle interaction.

JDFTx: Software for joint density-functional theory

DOE PAGES

Sundararaman, Ravishankar; Letchworth-Weaver, Kendra; Schwarz, Kathleen A.; ...

2017-11-14

Density-functional theory (DFT) has revolutionized computational prediction of atomic-scale properties from first principles in physics, chemistry and materials science. Continuing development of new methods is necessary for accurate predictions of new classes of materials and properties, and for connecting to nano- and mesoscale properties using coarse-grained theories. JDFTx is a fully-featured open-source electronic DFT software designed specifically to facilitate rapid development of new theories, models and algorithms. Using an algebraic formulation as an abstraction layer, compact C++11 code automatically performs well on diverse hardware including GPUs (Graphics Processing Units). This code hosts the development of joint density-functional theory (JDFT) thatmore » combines electronic DFT with classical DFT and continuum models of liquids for first-principles calculations of solvated and electrochemical systems. In addition, the modular nature of the code makes it easy to extend and interface with, facilitating the development of multi-scale toolkits that connect to ab initio calculations, e.g. photo-excited carrier dynamics combining electron and phonon calculations with electromagnetic simulations.« less

JDFTx: Software for joint density-functional theory

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

Sundararaman, Ravishankar; Letchworth-Weaver, Kendra; Schwarz, Kathleen A.

Density-functional theory (DFT) has revolutionized computational prediction of atomic-scale properties from first principles in physics, chemistry and materials science. Continuing development of new methods is necessary for accurate predictions of new classes of materials and properties, and for connecting to nano- and mesoscale properties using coarse-grained theories. JDFTx is a fully-featured open-source electronic DFT software designed specifically to facilitate rapid development of new theories, models and algorithms. Using an algebraic formulation as an abstraction layer, compact C++11 code automatically performs well on diverse hardware including GPUs (Graphics Processing Units). This code hosts the development of joint density-functional theory (JDFT) thatmore » combines electronic DFT with classical DFT and continuum models of liquids for first-principles calculations of solvated and electrochemical systems. In addition, the modular nature of the code makes it easy to extend and interface with, facilitating the development of multi-scale toolkits that connect to ab initio calculations, e.g. photo-excited carrier dynamics combining electron and phonon calculations with electromagnetic simulations.« less

Simulations of the interaction of intense petawatt laser pulses with dense Z-pinch plasmas : final report LDRD 39670.

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

Welch, Dale Robert; MacFarlane, Joseph John; Mehlhorn, Thomas Alan

We have studied the feasibility of using the 3D fully electromagnetic implicit hybrid particle code LSP (Large Scale Plasma) to study laser plasma interactions with dense, compressed plasmas like those created with Z, and which might be created with the planned ZR. We have determined that with the proper additional physics and numerical algorithms developed during the LDRD period, LSP was transformed into a unique platform for studying such interactions. Its uniqueness stems from its ability to consider realistic compressed densities and low initial target temperatures (if required), an ability that conventional PIC codes do not possess. Through several testmore » cases, validations, and applications to next generation machines described in this report, we have established the suitability of the code to look at fast ignition issues for ZR, as well as other high-density laser plasma interaction problems relevant to the HEDP program at Sandia (e.g. backlighting).« less

Numerical Simulation of the Variation of Schumann Resonance Associated with Seismogenic Processe in the Lithosphere-Atmosphere-Ionosphere system

NASA Astrophysics Data System (ADS)

Liu, L.; Huang, Q.; Wang, Y.

2012-12-01

The variations in the strength and frequency shift of the Schumann resonance (SR) of the electromagnetic (EM) field prior to some significance earthquakes were reported by a number of researchers. As a robust physical phenomenon constantly exists in the resonant cavity formed by the lithosphere-atmosphere-ionosphere system, irregular variations in SR parameters can be naturally attributed to be the potential precursory observables for forecasting earthquake occurrences. Schumann resonance (SR) of the EM field between the lithosphere and the ionosphere occurs because the space between the surface of the Earth and the conductive ionosphere acts as a closed waveguide. The cavity is naturally excited by electric currents generated by lightning. SR is the principal background in the electromagnetic spectrum at extremely low frequencies (ELF) between 3-69 Hz. We simulated the EM field in the lithosphere-ionosphere waveguide with a 2-dimensional (2D), cylindrical whole-earth model by the hybrid pseudo-spectral and finite difference time domain method. Considering the seismogensis as a fully coupled seismoelectric process, we simulate the seismic wave and EM wave in this 2D model. The excitation of SR in the background EM field are generated by the electric-current impulses due to lightning thunderstorms within the lowest 10 kilometers of the atmosphere . The diurnal variation and the latitude-dependence in ion concentration in the ionosphere are included in the model. After the SR has reached the steady state, the impulse generated by the seismogenic process (pre-, co- and post-seismic) in the crust is introduced to assess the possible precursory effects on SR strength and frequency. The modeling results explain the observed fact of why SR has a much more sensitive response to continental earthquakes, and much less response to oceanic events; the reason is simply due to the shielding effect of the conductive ocean that prevents effective radiation of the seismoelectric signals into the lithosphere- ionosphere waveguide.; Resonance cavity model formed by the lithosphere-atmosphere-ionosphere system (illustrative, not to the scale of the Earth).

CICART Center For Integrated Computation And Analysis Of Reconnection And Turbulence

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

Bhattacharjee, Amitava

CICART is a partnership between the University of New Hampshire (UNH) and Dartmouth College. CICART addresses two important science needs of the DoE: the basic understanding of magnetic reconnection and turbulence that strongly impacts the performance of fusion plasmas, and the development of new mathematical and computational tools that enable the modeling and control of these phenomena. The principal participants of CICART constitute an interdisciplinary group, drawn from the communities of applied mathematics, astrophysics, computational physics, fluid dynamics, and fusion physics. It is a main premise of CICART that fundamental aspects of magnetic reconnection and turbulence in fusion devices, smaller-scalemore » laboratory experiments, and space and astrophysical plasmas can be viewed from a common perspective, and that progress in understanding in any of these interconnected fields is likely to lead to progress in others. The establishment of CICART has strongly impacted the education and research mission of a new Program in Integrated Applied Mathematics in the College of Engineering and Applied Sciences at UNH by enabling the recruitment of a tenure-track faculty member, supported equally by UNH and CICART, and the establishment of an IBM-UNH Computing Alliance. The proposed areas of research in magnetic reconnection and turbulence in astrophysical, space, and laboratory plasmas include the following topics: (A) Reconnection and secondary instabilities in large high-Lundquist-number plasmas, (B) Particle acceleration in the presence of multiple magnetic islands, (C) Gyrokinetic reconnection: comparison with fluid and particle-in-cell models, (D) Imbalanced turbulence, (E) Ion heating, and (F) Turbulence in laboratory (including fusion-relevant) experiments. These theoretical studies make active use of three high-performance computer simulation codes: (1) The Magnetic Reconnection Code, based on extended two-fluid (or Hall MHD) equations, in an Adaptive Mesh Refinement (AMR) framework, (2) the Particle Simulation Code, a fully electromagnetic 3D Particle-In-Cell (PIC) code that includes a collision operator, and (3) GS2, an Eulerian, electromagnetic, kinetic code that is widely used in the fusion program, and simulates the nonlinear gyrokinetic equations, together with a self-consistent set of Maxwell’s equations.« less

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.

Black Hole Simulation

NASA Image and Video Library

1999-11-30

This graphic shows the computer simulation of a black hole from start to finish. Plasma is falling slowly toward the black hole in a (at the upper left). The plasma has a magnetic field, shown by the white lines. It picks up speed as it falls toward the hole in b (at the upper right), c (lower left) and d (lower right). However, the rotating black hole twists up space itself (and the magnetic field lines) and ejects electromagnetic power along the north and south poles above the black hole. The red and white color shows the immense electromagnetic power output, which eventually will pick up particles and form squirting jets. This simulation was conducted using supercomputers at Japan's National Institute for Fusion Science. http://photojournal.jpl.nasa.gov/catalog/PIA04206

Evaluation of Honeywell Recoverable Computer System (RCS) in Presence of Electromagnetic Effects

NASA Technical Reports Server (NTRS)

Malekpour, Mahyar

1997-01-01

The design and development of a Closed-Loop System to study and evaluate the performance of the Honeywell Recoverable Computer System (RCS) in electromagnetic environments (EME) is presented. The development of a Windows-based software package to handle the time critical communication of data and commands between the RCS and flight simulation code in real-time, while meeting the stringent hard deadlines is also presented. The performance results of the RCS while exercising flight control laws under ideal conditions as well as in the presence of electromagnetic fields is also discussed.

Electromagnetic Launch Vehicle Fairing and Acoustic Blanket Model of Received Power Using FEKO

NASA Technical Reports Server (NTRS)

Trout, Dawn H.; Stanley, James E.; Wahid, Parveen F.

2011-01-01

Evaluating the impact of radio frequency transmission in vehicle fairings is important to sensitive spacecraft. This paper employees the Multilevel Fast Multipole Method (MLFMM) feature of a commercial electromagnetic tool to model the fairing electromagnetic environment in the presence of an internal transmitter. This work is an extension of the perfect electric conductor model that was used to represent the bare aluminum internal fairing cavity. This fairing model includes typical acoustic blanketing commonly used in vehicle fairings. Representative material models within FEKO were successfully used to simulate the test case.

Characteristics of electromagnetic interference generated during discharge of Mylar samples. [spacecraft-environment interaction simulation

NASA Technical Reports Server (NTRS)

Leung, P. L.

1984-01-01

This paper discusses the measurements of the electromagnetic interference (EMI) generated during discharges of Mylar samples. The two components of EMI, the conducted emission and the radiated emission, are characterized by the replacement current and the radiated RF spectrum respectively. The measured radiated RF spectra reveal important information on the source of the electromagnetic radiation. The possible sources are the replacement current pulse and the discharged generated plasma. The scaling of the amplitudes of the EMI, as a function of the area of the test sample, is also discussed.

Massive Black Hole Mergers: Can We "See" what LISA will "Hear"?

NASA Technical Reports Server (NTRS)

Centrella, Joan

2010-01-01

The final merger of massive black holes produces strong gravitational radiation that can be detected by the space-borne LISA. If the black hole merger takes place in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. Modeling such electromagnetic counterparts of the final merger requires evolving the behavior of both gas and fields in the strong-field regions around the black holes. We will review current efforts to simulate these systems, and discuss possibilities for observing the electromagnetic signals they produce.

Modeling of Mutiscale Electromagnetic Magnetosphere-Ionosphere Interactions near Discrete Auroral Arcs Observed by the MICA Sounding Rocket

NASA Astrophysics Data System (ADS)

Streltsov, A. V.; Lynch, K. A.; Fernandes, P. A.; Miceli, R.; Hampton, D. L.; Michell, R. G.; Samara, M.

2012-12-01

The MICA (Magnetosphere-Ionosphere Coupling in the Alfvén Resonator) sounding rocket was launched from Poker Flat on February 19, 2012. The rocket was aimed into the system of discrete auroral arcs and during its flight it detected small-scale electromagnetic disturbances with characteristic features of dispersive Alfvén waves. We report results from numerical modeling of these observations. Our simulations are based on a two-fluid MHD model describing multi-scale interactions between magnetic field-aligned currents carried by shear Alfven waves and the ionosphere. The results from our simulations suggest that the small-scale electromagnetic structures measured by MICA indeed can be interpreted as dispersive Alfvén waves generated by the active ionospheric response (ionopspheric feedback instability) inside the large-scale downward magnetic field-aligned current interacting with the ionosphere.

Water-injected all-dielectric ultra-wideband and prominent oblique incidence metamaterial absorber in microwave regime

NASA Astrophysics Data System (ADS)

Huang, Xiaojun; Yang, Helin; Shen, Zhaoyang; Chen, Jiao; Lin, Hail; Yu, Zetai

2017-09-01

We present a water-injected all-dielectric metamaterial that can offer an extremely wide bandwidth of electromagnetic absorption and prominent wide incident angle range. Different from conventional metal-dielectric based metamaterial absorbers, the absorption mechanism of the proposed all-dielectric metamaterial absorber is to take advantage of the dispersion of water, rather than electric or/and magnetic resonance, which thoroughly overcomes the defects of narrow bandwidth and oblique incidence from metal-dielectric based metamaterial absorber. The simulated absorption was over 90% in 8.1-22.9 GHz with the relative bandwidth of 95.5% when the incident angle reaches 60°, and the corresponding microwave experiment is performed to support the simulations. The obtained excellent absorption performance reveals a possible application of the proposed absorber, which can be exploited for electromagnetic stealth purposes, especially for electromagnetic stealth of sea targets.

Advanced Fast 3-D Electromagnetic Solver for Microwave Tomography Imaging.

PubMed

Simonov, Nikolai; Kim, Bo-Ra; Lee, Kwang-Jae; Jeon, Soon-Ik; Son, Seong-Ho

2017-10-01

This paper describes a fast-forward electromagnetic solver (FFS) for the image reconstruction algorithm of our microwave tomography system. Our apparatus is a preclinical prototype of a biomedical imaging system, designed for the purpose of early breast cancer detection. It operates in the 3-6-GHz frequency band using a circular array of probe antennas immersed in a matching liquid; it produces image reconstructions of the permittivity and conductivity profiles of the breast under examination. Our reconstruction algorithm solves the electromagnetic (EM) inverse problem and takes into account the real EM properties of the probe antenna array as well as the influence of the patient's body and that of the upper metal screen sheet. This FFS algorithm is much faster than conventional EM simulation solvers. In comparison, in the same PC, the CST solver takes ~45 min, while the FFS takes ~1 s of effective simulation time for the same EM model of a numerical breast phantom.

General Relativistic Simulations of Magnetized Plasmas Around Merging Supermassive Black Holes

NASA Technical Reports Server (NTRS)

Giacomazzo, Bruno; Baker, John G.; Miller, M. Coleman; Reynolds, Christopher S.; van Meter, James R.

2012-01-01

Coalescing supermassive black hole binaries are produced by the mergers of galaxies and are the most powerful sources of gravitational waves accessible to space-based gravitational observatories. Some such mergers may occur in the presence of matter and magnetic fields and hence generate an electromagnetic counterpart. In this paper we present the first general relativistic simulations of magnetized plasma around merging supermassive black holes using the general relativistic magnetohydrodynamic code Whisky. By considering different magnetic field strengths, going from non-magnetically dominated to magnetically dominated regimes, we explore how magnetic fields affect the dynamics of the plasma and the possible emission of electromagnetic signals. In particular we observe, total amplification of the magnetic field of approx 2 orders of magnitude which is driven by the accretion onto the binary and that leads to stronger electromagnetic signals than in the force-free regime where such amplifications are not possible.

Electromagnetic absorption in the head of adults and children due to mobile phone operation close to the head.

PubMed

de Salles, Alvaro A; Bulla, Giovani; Rodriguez, Claudio E Fernández

2006-01-01

The Specific Absorption Rate (SAR) produced by mobile phones in the head of adults and children is simulated using an algorithm based on the Finite Difference Time Domain (FDTD) method. Realistic models of the child and adult head are used. The electromagnetic parameters are fitted to these models. Comparison also are made with the SAR calculated in the children model when using adult human electromagnetic parameters values. Microstrip (or patch) antennas and quarter wavelength monopole antennas are used in the simulations. The frequencies used to feed the antennas are 1850 MHz and 850 MHz. The SAR results are compared with the available international recommendations. It is shown that under similar conditions, the 1g-SAR calculated for children is higher than that for the adults. When using the 10-year old child model, SAR values higher than 60% than those for adults are obtained.

Isentropic Compression with a Rectangular Configuration for Tungstene and Tantalum, Computations and Comparison with Experiments

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

Lefrancois, A.; Reisman, D. B.; Bastea, M.

2006-02-13

Isentropic compression experiments and numerical simulations on metals are performed at Z accelerator facility from Sandia National Laboratory and at Lawrence Livermore National Laboratory in order to study the isentrope, associated Hugoniot and phase changes of these metals. 3D configurations have been calculated here to benchmark the new beta version of the electromagnetism package coupled with the dynamics in Ls-Dyna and compared with the ICE Z shots 1511 and 1555. The electromagnetism module is being developed in the general-purpose explicit and implicit finite element program LS-DYNA{reg_sign} in order to perform coupled mechanical/thermal/electromagnetism simulations. The Maxwell equations are solved using amore » Finite Element Method (FEM) for the solid conductors coupled with a Boundary Element Method (BEM) for the surrounding air (or vacuum). More details can be read in the references.« less

Tests of the module array of the ECAL0 electromagnetic calorimeter for the COMPASS experiment with the electron beam at ELSA

NASA Astrophysics Data System (ADS)

Anfimov, N.; Anosov, V.; Barth, J.; Chalyshev, V.; Chirikov-Zorin, I.; Dziewiecki, M.; Elsner, D.; Frolov, V.; Frommberger, F.; Guskov, A.; Hillert, W.; Klein, F.; Krumshteyn, Z.; Kurjata, R.; Marzec, J.; Nagaytsev, A.; Olchevski, A.; Orlov, I.; Rezinko, T.; Rybnikov, A.; Rychter, A.; Selyunin, A.; Zaremba, K.; Ziembicki, M.

2015-07-01

The array of 3 × 3 modules of the electromagnetic calorimeter ECAL0 of the COMPASS experiment at CERN has been tested with an electron beam of the ELSA (Germany) facility. The dependence of the response and the energy resolution of the calorimeter from the angle of incidence of the electron beam has been studied. A good agreement between the experimental data and the results of Monte Carlo simulation has been obtained. It will significantly expand the use of simulation to optimize event reconstruction algorithms.

A Triaxial Applicator for the Measurement of the Electromagnetic Properties of Materials

PubMed Central

2018-01-01

The design, analysis, and fabrication of a prototype triaxial applicator is described. The applicator provides both reflected and transmitted signals that can be used to characterize the electromagnetic properties of materials in situ. A method for calibrating the probe is outlined and validated using simulated data. Fabrication of the probe is discussed, and measured data for typical absorbing materials and for the probe situated in air are presented. The simulations and measurements suggest that the probe should be useful for measuring the properties of common radar absorbing materials under usual in situ conditions. PMID:29382122

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.

Electromagnetic Modelling of MMIC CPWs for High Frequency Applications

NASA Astrophysics Data System (ADS)

Sinulingga, E. P.; Kyabaggu, P. B. K.; Rezazadeh, A. A.

2018-02-01

Realising the theoretical electrical characteristics of components through modelling can be carried out using computer-aided design (CAD) simulation tools. If the simulation model provides the expected characteristics, the fabrication process of Monolithic Microwave Integrated Circuit (MMIC) can be performed for experimental verification purposes. Therefore improvements can be suggested before mass fabrication takes place. This research concentrates on development of MMIC technology by providing accurate predictions of the characteristics of MMIC components using an improved Electromagnetic (EM) modelling technique. The knowledge acquired from the modelling and characterisation process in this work can be adopted by circuit designers for various high frequency applications.

Simulation of TunneLadder traveling-wave tube cold-test characteristics: Implementation of the three-dimensional, electromagnetic circuit analysis code micro-SOS

NASA Technical Reports Server (NTRS)

Kory, Carol L.; Wilson, Jeffrey D.

1993-01-01

The three-dimensional, electromagnetic circuit analysis code, Micro-SOS, can be used to reduce expensive time-consuming experimental 'cold-testing' of traveling-wave tube (TWT) circuits. The frequency-phase dispersion characteristics and beam interaction impedance of a TunneLadder traveling-wave tube slow-wave structure were simulated using the code. When reasonable dimensional adjustments are made, computer results agree closely with experimental data. Modifications to the circuit geometry that would make the TunneLadder TWT easier to fabricate for higher frequency operation are explored.

3D Electromagnetic Particle-in-Cell simulations of the solar wind interaction with lunar magnetic anomalies

NASA Astrophysics Data System (ADS)

Deca, J.; Lapenta, G.; Divin, A. V.; Lembege, B.; Markidis, S.

2013-12-01

Unlike the Earth and Mercury, our Moon has no global magnetic field and is therefore not shielded from the impinging solar wind by a magnetosphere. However, lunar magnetic field measurements made by the Apollo missions provided direct evidence that the Moon has regions of small-scale crustal magnetic fields, ranging up to a few 100km in scale size with surface magnetic field strengths up to hundreds of nanoTeslas. More recently, the Lunar Prospector spacecraft has provided high-resolution observations allowing to construct magnetic field maps of the entire Moon, confirming the earlier results from Apollo, but also showing that the lunar plasma environment is much richer than earlier believed. Typically the small-scale magnetic fields are non-dipolar and rather tiny compared to the lunar radius and mainly clustered on the far side of the moon. Using iPic3D we present the first 3D fully kinetic and electromagnetic Particle-in-Cell simulations of the solar wind interaction with lunar magnetic anomalies. We study the behaviour of a dipole model with variable surface magnetic field strength under changing solar wind conditions and confirm that lunar crustal magnetic fields may indeed be strong enough to stand off the solar wind and form a mini-magnetosphere, as suggested by MHD and hybrid simulations and spacecraft observations. 3D-PIC simulations reveal to be very helpful to analyze the diversion/braking of the particle flux and the characteristics of the resulting particles accumulation. The particle flux to the surface is significantly reduced at the magnetic anomaly, surrounded by a region of enhanced density due to the magnetic mirror effect. Second, the ability of iPic3D to resolve all plasma components (heavy ions, protons and electrons) allows to discuss in detail the electron physics leading to the highly non-adiabatic interactions expected as well as the implications for solar wind shielding of the lunar surface, depending on the scale size (solar wind protons typically have gyroradii larger than the magnetic anomaly scale size) and magnetic field strength. The research leading to these results has received funding from the European Commission's Seventh Framework Programme (FP7/2007-2013) under the grant agreement SWIFF (project 2633430, swiff.eu). Cut along the dipole axis of the lunar anomaly, showing the electron density structure.

A hybrid Boundary Element Unstructured Transmission-line (BEUT) method for accurate 2D electromagnetic simulation

NASA Astrophysics Data System (ADS)

Simmons, Daniel; Cools, Kristof; Sewell, Phillip

2016-11-01

Time domain electromagnetic simulation tools have the ability to model transient, wide-band applications, and non-linear problems. The Boundary Element Method (BEM) and the Transmission Line Modeling (TLM) method are both well established numerical techniques for simulating time-varying electromagnetic fields. The former surface based method can accurately describe outwardly radiating fields from piecewise uniform objects and efficiently deals with large domains filled with homogeneous media. The latter volume based method can describe inhomogeneous and non-linear media and has been proven to be unconditionally stable. Furthermore, the Unstructured TLM (UTLM) enables modelling of geometrically complex objects by using triangular meshes which removes staircasing and unnecessary extensions of the simulation domain. The hybridization of BEM and UTLM which is described in this paper is named the Boundary Element Unstructured Transmission-line (BEUT) method. It incorporates the advantages of both methods. The theory and derivation of the 2D BEUT method is described in this paper, along with any relevant implementation details. The method is corroborated by studying its correctness and efficiency compared to the traditional UTLM method when applied to complex problems such as the transmission through a system of Luneburg lenses and the modelling of antenna radomes for use in wireless communications.

A hybrid Boundary Element Unstructured Transmission-line (BEUT) method for accurate 2D electromagnetic simulation

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

Simmons, Daniel, E-mail: daniel.simmons@nottingham.ac.uk; Cools, Kristof; Sewell, Phillip

Time domain electromagnetic simulation tools have the ability to model transient, wide-band applications, and non-linear problems. The Boundary Element Method (BEM) and the Transmission Line Modeling (TLM) method are both well established numerical techniques for simulating time-varying electromagnetic fields. The former surface based method can accurately describe outwardly radiating fields from piecewise uniform objects and efficiently deals with large domains filled with homogeneous media. The latter volume based method can describe inhomogeneous and non-linear media and has been proven to be unconditionally stable. Furthermore, the Unstructured TLM (UTLM) enables modelling of geometrically complex objects by using triangular meshes which removesmore » staircasing and unnecessary extensions of the simulation domain. The hybridization of BEM and UTLM which is described in this paper is named the Boundary Element Unstructured Transmission-line (BEUT) method. It incorporates the advantages of both methods. The theory and derivation of the 2D BEUT method is described in this paper, along with any relevant implementation details. The method is corroborated by studying its correctness and efficiency compared to the traditional UTLM method when applied to complex problems such as the transmission through a system of Luneburg lenses and the modelling of antenna radomes for use in wireless communications. - Graphical abstract:.« less

Propagation of three-dimensional bipolar ultrashort electromagnetic pulses in an inhomogeneous array of carbon nanotubes

NASA Astrophysics Data System (ADS)

Fedorov, Eduard G.; Zhukov, Alexander V.; Bouffanais, Roland; Timashkov, Alexander P.; Malomed, Boris A.; Leblond, Hervé; Mihalache, Dumitru; Rosanov, Nikolay N.; Belonenko, Mikhail B.

2018-04-01

We study the propagation of three-dimensional (3D) bipolar ultrashort electromagnetic pulses in an inhomogeneous array of semiconductor carbon nanotubes. The heterogeneity is represented by a planar region with an increased concentration of conduction electrons. The evolution of the electromagnetic field and electron concentration in the sample are governed by the Maxwell's equations and continuity equation. In particular, nonuniformity of the electromagnetic field along the axis of the nanotubes is taken into account. We demonstrate that depending on values of the parameters of the electromagnetic pulse approaching the region with the higher electron concentration, the pulse is either reflected from the region or passes it. Specifically, our simulations demonstrate that after interacting with the higher-concentration area, the pulse can propagate steadily, without significant spreading. The possibility of such ultrashort electromagnetic pulses propagating in arrays of carbon nanotubes over distances significantly exceeding characteristic dimensions of the pulses makes it possible to consider them as 3D solitons.

Geophysical identification of subsurface cavities and fractures near a Superfund site south of Rockford, Illinois

NASA Astrophysics Data System (ADS)

Adams, Ryan Frye

The ACME Superfund site is one of many Superfund sites in Northern Illinois. This 20 acre (8.1 ha) site was contaminated by various volatile organic compounds (VOC's) and heavy metals during the 1960-1980s. To more fully understand the potential extent of the karst system and its interaction with contaminants, both surface and borehole geophysics including seismic refraction tomography, frequency domain electromagnetics, electrical resistivity, ground penetrating radar, as well as natural gamma and electromagnetic well logs, were undertaken over an approximately 3,000 square meter grid in a field immediately south of the ACME site. Seismic refraction tomography provided information on lithology and fluctuations in the bedrock surface in the depth range 6 to 8 m. Refraction, combined with electromagnetic conductivity, also allowed mapping of potential soil pipes and/or filled sinkholes in the overlying soils. These could channel surface waters into the karst conduit system. Frequency domain electromagnetics proved to be the most successful tool for the identifying possible karst conduits below the bedrock surface. Zones of reduced conductivity suggest a series of interconnected solutionally enlarged fractures in an orthogonal pattern at a depth of approximately 8 m immediately south of the ACME site.

Kurtosis parameter K of arbitrary electromagnetic beams propagating through non-Kolmogorov turbulence

NASA Astrophysics Data System (ADS)

Xu, Yonggen; Dan, Youquan; Yu, Jiayi; Cai, Yangjian

2017-10-01

General analytical formulae for the kurtosis parameters K (K parameters) of the arbitrary electromagnetic (AE) beams propagating through non-Kolmogorov turbulence are derived, and according to the unified theory of polarization and coherence, the effect of degree of polarization (DOP) of an electromagnetic beam on the K parameter is studied. The analytical formulae can be given by the second-order moments and fourth-order moments of the Wigner distribution function for AE beams at source plane, the two turbulence quantities relating to the spatial power spectrum, and the propagation distance. Our results can also be extended to the arbitrary beams and the arbitrary spatial power spectra of Kolmogorov turbulence or non-Kolmogorov turbulence. Taking the stochastic electromagnetic Gaussian Schell-model (SEGSM) beam as an example, the numerical examples indicate that the K parameters of a SEGSM beam in non-Kolmogorov turbulence depend on propagation distance, the beam parameters and turbulence parameters. The K parameter of a SEGM beam is more sensitive to effect of turbulence with smaller inner scale and generalized exponent parameter. A non-polarized light has the strongest ability of resisting turbulence (ART), however, a fully polarized SEGSM beam has the poorest ART.

Rotating and Binary Stars in General Relativit

NASA Astrophysics Data System (ADS)

Shapiro, Stuart

The inspiral and coalescence of compact binary stars is one of the most challenging problems in theoretical astrophysics. Only recently have advances in numerical relativity made it possible to explore this topic in full general relativity (GR). The mergers of compact binaries have important consequences for the detection of gravitational waves. In addition, the coalescence of binary neutron stars (NSNSs) and binary black-hole neutron stars (BHNSs) may hold the key for resolving other astrophysical puzzles, such as the origin of short-hard gamma-ray bursts (GRBs). While simulations of these systems in full GR are now possible, only the most idealized treatments have been performed to date. More detailed physics, including magnetic fields, black hole spin, a realistic hot, nuclear equation of state and neutrino transport must be incorporated. Only then will we be able to identify reliably future sources that may be detected simultaneously in gravitational waves and as GRBs. Likewise, the coalescence of binary black holes (BHBHs) is now a solved problem in GR, but only in vacuum. Simulating the coalescence of BHBHs in the gaseous environments likely to be found in nearby galaxy cores or in merging galaxies is crucial to identifying an electromagnetic signal that might accompany the gravitational waves produced during the merger. The coalescence of a binary white dwarf-neutron star (WDNS) has only recently been treated in GR, but GR is necessary to explore tidal disruption scenarios in which the capture of WD debris by the NS may lead to catastrophic collapse. Alternatively, the NS may survive and the merger might result in the formation of pulsar planets. The stability of rotating neutron stars in these and other systems has not been fully explored in GR, and the final fate of unstable stars has not been determined in many cases, especially in the presence of magnetic fields and differential rotation. These systems will be probed observationally by current NASA instruments, such as HST, CHANDRA, SWIFT and FERMI, and by future NASA detectors, such as NuStar, ASTRO-H, GEMS, JWST, and, possibly, GEN-X and SGO (a Space-Based Gravitational-Wave Observatory). Treating all of these phenomena theoretically requires the same computational machinery: a fully relativistic code that simultaneously solves Einstein s equations for the gravitational field, Maxwell s equations for the electromagnetic field and the equations of relativistic magnetohydrodynamics for the plasma, all in three spatial dimensions plus time. Recent advances we have made in constructing such a code now make it possible for us to solve these fundamental, closely related computational problems, some for the first time.

Computational Electronics and Electromagnetics

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

DeFord, J.F.

The Computational Electronics and Electromagnetics thrust area is a focal point for computer modeling activities in electronics and electromagnetics in the Electronics Engineering Department of Lawrence Livermore National Laboratory (LLNL). Traditionally, they have focused their efforts in technical areas of importance to existing and developing LLNL programs, and this continues to form the basis for much of their research. A relatively new and increasingly important emphasis for the thrust area is the formation of partnerships with industry and the application of their simulation technology and expertise to the solution of problems faced by industry. The activities of the thrust areamore » fall into three broad categories: (1) the development of theoretical and computational models of electronic and electromagnetic phenomena, (2) the development of useful and robust software tools based on these models, and (3) the application of these tools to programmatic and industrial problems. In FY-92, they worked on projects in all of the areas outlined above. The object of their work on numerical electromagnetic algorithms continues to be the improvement of time-domain algorithms for electromagnetic simulation on unstructured conforming grids. The thrust area is also investigating various technologies for conforming-grid mesh generation to simplify the application of their advanced field solvers to design problems involving complicated geometries. They are developing a major code suite based on the three-dimensional (3-D), conforming-grid, time-domain code DSI3D. They continue to maintain and distribute the 3-D, finite-difference time-domain (FDTD) code TSAR, which is installed at several dozen university, government, and industry sites.« less

Design Optimization of an Electromagnetic Energy Harvester Backpack for Utilization of Human Walking Energy

NASA Astrophysics Data System (ADS)

Mullen, Christopher

Implementation of energy harvesting technology can provide a sustainable, remote power source for soldiers by reducing the battery weight and allowing them to stay in the field for longer periods of time. Among multiple energy conversion principles, electromagnetic induction can scavenge energy from wasted kinematic and vibration energy found from human motion. Hip displacement during human gait acts as a base excitation for an energy harvesting backpack system. The placement of a permanent magnet in this vibration environment results in relative motion of the magnet to the coil of copper wire, which induces an electric current. This current can be saved to a battery or capacitor bank installed on the backpack to be used to power electronic devices. The purpose of this research is to construct a reliable simulation model for an electromagnetic vibration energy harvester and use it for a multi-variable optimization algorithm to identify an optimal coil and magnet layout for highest power output. Key components of the coupled equations of motion such as the magnetic flux density and coil inductance are obtained using ANSYS multi-physics software or by measuring them. These components are fed into a harvester simulation model (e.g. coupled field equations of motion for the backpack harvester) that generates the electrical power output. The developed simulation model is verified with multiple case studies including an experimental test. Then the optimal design parameters in the simulation model (e.g., magnet layout, coil width, outer coil diameter, external load resistance) are identified for maximum power. Results from this study will pave the way for a more efficient energy harvesting backpack while providing better insight into the efficiency of magnet and coil layout for electromagnetic applications.

Experimental verification and optimization of a linear electromagnetic energy harvesting device

NASA Astrophysics Data System (ADS)

Mullen, Christopher; Lee, Soobum

2017-04-01

Implementation of energy harvesting technology can provide a sustainable, remote power source for soldiers by reducing the battery weight and allowing them to stay in the field for longer periods of time. Among multiple energy conversion principles, electromagnetic induction can scavenge energy from wasted kinematic and vibration energy found from human motion. Hip displacement during human gait acts as a base excitation for an energy harvesting backpack system. The placement of a permanent magnet in this vibration environment results in relative motion of the magnet to the coil of copper wire, which induces an electric current. This current can be saved to a battery or capacitor bank installed on the backpack to be used to power electronic devices. The purpose of this research is to construct a reliable simulation model for an electromagnetic vibration energy harvester and use it for a multi-variable optimization algorithm to identify an optimal coil and magnet layout for highest power output. Key components of the coupled equations of motion such as the magnetic flux density and coil inductance are obtained using ANSYS multi-physics software or by measuring them. These components are fed into a harvester simulation model (e.g. coupled field equations of motion for the backpack harvester) that generates the electrical power output. The developed simulation model is verified with a case study including an experimental test. Then the optimal design parameters in the simulation model (e.g., magnet layout, coil width, outer coil diameter, external load resistance) are identified for maximum power. Results from this study will pave the way for a more efficient energy harvesting backpack while providing better insight into the efficiency of magnet and coil layout for electromagnetic applications.

Single-cycle high-intensity electromagnetic pulse generation in the interaction of a plasma wakefield with regular nonlinear structures.

PubMed

Bulanov, S S; Esirkepov, T Zh; Kamenets, F F; Pegoraro, F

2006-03-01

The interaction of regular nonlinear structures (such as subcycle solitons, electron vortices, and wake Langmuir waves) with a strong wake wave in a collisionless plasma can be exploited in order to produce ultrashort electromagnetic pulses. The electromagnetic field of the nonlinear structure is partially reflected by the electron density modulations of the incident wake wave and a single-cycle high-intensity electromagnetic pulse is formed. Due to the Doppler effect the length of this pulse is much shorter than that of the nonlinear structure. This process is illustrated with two-dimensional particle-in-cell simulations. The considered laser-plasma interaction regimes can be achieved in present day experiments and can be used for plasma diagnostics.

Explicit symplectic algorithms based on generating functions for relativistic charged particle dynamics in time-dependent electromagnetic field

NASA Astrophysics Data System (ADS)

Zhang, Ruili; Wang, Yulei; He, Yang; Xiao, Jianyuan; Liu, Jian; Qin, Hong; Tang, Yifa

2018-02-01

Relativistic dynamics of a charged particle in time-dependent electromagnetic fields has theoretical significance and a wide range of applications. The numerical simulation of relativistic dynamics is often multi-scale and requires accurate long-term numerical simulations. Therefore, explicit symplectic algorithms are much more preferable than non-symplectic methods and implicit symplectic algorithms. In this paper, we employ the proper time and express the Hamiltonian as the sum of exactly solvable terms and product-separable terms in space-time coordinates. Then, we give the explicit symplectic algorithms based on the generating functions of orders 2 and 3 for relativistic dynamics of a charged particle. The methodology is not new, which has been applied to non-relativistic dynamics of charged particles, but the algorithm for relativistic dynamics has much significance in practical simulations, such as the secular simulation of runaway electrons in tokamaks.

State of the art in electromagnetic modeling for the Compact Linear Collider

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

Candel, Arno; Kabel, Andreas; Lee, Lie-Quan

SLAC's Advanced Computations Department (ACD) has developed the parallel 3D electromagnetic time-domain code T3P for simulations of wakefields and transients in complex accelerator structures. T3P is based on state-of-the-art Finite Element methods on unstructured grids and features unconditional stability, quadratic surface approximation and up to 6th-order vector basis functions for unprecedented simulation accuracy. Optimized for large-scale parallel processing on leadership supercomputing facilities, T3P allows simulations of realistic 3D structures with fast turn-around times, aiding the design of the next generation of accelerator facilities. Applications include simulations of the proposed two-beam accelerator structures for the Compact Linear Collider (CLIC) - wakefieldmore » damping in the Power Extraction and Transfer Structure (PETS) and power transfer to the main beam accelerating structures are investigated.« less

Low-loss negative index metamaterials for X, Ku, and K microwave bands

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

Lee, David A.; Vedral, L. James; Smith, David A.

2015-04-15

Low-loss, negative-index of refraction metamaterials were designed and tested for X, Ku, and K microwave frequency bands. An S-shaped, split-ring resonator was used as a unit cell to design homogeneous slabs of negative-index metamaterials. Then, the slabs of metamaterials were cut unto prisms to measure experimentally the negative index of refraction of a plane electromagnetic wave. Theoretical simulations using High-Frequency Structural Simulator, a finite element equation solver, were in good agreement with experimental measurements. The negative index of refraction was retrieved from the angle- and frequency-dependence of the transmitted intensity of the microwave beam through the metamaterial prism and comparedmore » well to simulations; in addition, near-field electromagnetic intensity mapping was conducted with an infrared camera, and there was also a good match with the simulations for expected frequency ranges for the negative index of refraction.« less

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.

3D highly heterogeneous thermal model of pineal gland in-vitro study for electromagnetic exposure using finite volume method

NASA Astrophysics Data System (ADS)

Cen, Wei; Hoppe, Ralph; Lu, Rongbo; Cai, Zhaoquan; Gu, Ning

2017-08-01

In this paper, the relationship between electromagnetic power absorption and temperature distributions inside highly heterogeneous biological samples was accurately determinated using finite volume method. An in-vitro study on pineal gland that is responsible for physiological activities was for the first time simulated to illustrate effectiveness of the proposed method.

Electromagnetic tornadoes in space

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

Chang, T.; Crew, G.B.; Retterer, J.M.

1988-01-01

The exotic phenomenon of energetic-ion conic formation by plasma waves in the magnetosphere is considered. Two particular transverse heating mechanisms are reviewed in detail; lower-hybrid energization of ions in the boundary layer of the plasma sheet and electromagnetic ion cyclotron resonance heating in the central region of the plasma sheet. Mean particle calculations, plasma simulations and analytical treatments of the heating processes are described.

Illusion optics: Optically transforming the nature and the location of electromagnetic emissions

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

Yi, Jianjia; Tichit, Paul-Henri; Burokur, Shah Nawaz, E-mail: shah-nawaz.burokur@u-psud.fr

Complex electromagnetic structures can be designed by using the powerful concept of transformation electromagnetics. In this study, we define a spatial coordinate transformation that shows the possibility of designing a device capable of producing an illusion on an antenna radiation pattern. Indeed, by compressing the space containing a radiating element, we show that it is able to change the radiation pattern and to make the radiation location appear outside the latter space. Both continuous and discretized models with calculated electromagnetic parameter values are presented. A reduction of the electromagnetic material parameters is also proposed for a possible physical fabrication ofmore » the device with achievable values of permittivity and permeability that can be obtained from existing well-known metamaterials. Following that, the design of the proposed antenna using a layered metamaterial is presented. Full wave numerical simulations using Finite Element Method are performed to demonstrate the performances of such a device.« less

A hybrid power system for unmanned aerial vehicle electromagnetic launcher

NASA Astrophysics Data System (ADS)

Wang, Zhiren; Wu, Jun; Huang, Shengjun

2018-06-01

According to the UAV electromagnetic catapult with fixed timing, a hybrid energy storage system consist with battery and super capacitor is designed, in order to reduce the volume and weight of the energy storage system. The battery is regarded as the energy storage device and the super capacitor as power release device. Firstly, the battery charges the super capacitor, and then the super capacitor supplies power to electromagnetic catapult separately. The strategy is using the Buck circuit to charge the super capacitor with constant current and using the Boost circuit to make super capacitor provide a stable voltage circuit for electromagnetic catapult. The Simulink simulation results show that the designed hybrid energy storage system can meet the requirements of electromagnetic catapult. Compared with the system powered by the battery alone, the proposed scheme can reduce the number of batteries, and greatly reduce the volume and weight of the energy storage system.

Loop heating by D.C. electric current and electromagnetic wave emissions simulated by 3-D EM particle zone

NASA Technical Reports Server (NTRS)

Sakai, J. I.; Zhao, J.; Nishikawa, K.-I.

1994-01-01

We have shown that a current-carrying plasma loop can be heated by magnetic pinch driven by the pressure imbalance between inside and outside the loop, using a 3-dimensional electromagnetic (EM) particle code. Both electrons and ions in the loop can be heated in the direction perpendicular to the ambient magnetic field, therefore the perpendicular temperature can be increased about 10 times compared with the parallel temperature. This temperature anisotropy produced by the magnetic pinch heating can induce a plasma instability, by which high-frequency electromagnetic waves can be excited. The plasma current which is enhanced by the magnetic pinch can also excite a kinetic kink instability, which can heat ions perpendicular to the magnetic field. The heating mechanism of ions as well as the electromagnetic emission could be important for an understanding of the coronal loop heating and the electromagnetic wave emissions from active coronal regions.

Multi-objective design optimization of antenna structures using sequential domain patching with automated patch size determination

NASA Astrophysics Data System (ADS)

Koziel, Slawomir; Bekasiewicz, Adrian

2018-02-01

In this article, a simple yet efficient and reliable technique for fully automated multi-objective design optimization of antenna structures using sequential domain patching (SDP) is discussed. The optimization procedure according to SDP is a two-step process: (i) obtaining the initial set of Pareto-optimal designs representing the best possible trade-offs between considered conflicting objectives, and (ii) Pareto set refinement for yielding the optimal designs at the high-fidelity electromagnetic (EM) simulation model level. For the sake of computational efficiency, the first step is realized at the level of a low-fidelity (coarse-discretization) EM model by sequential construction and relocation of small design space segments (patches) in order to create a path connecting the extreme Pareto front designs obtained beforehand. The second stage involves response correction techniques and local response surface approximation models constructed by reusing EM simulation data acquired in the first step. A major contribution of this work is an automated procedure for determining the patch dimensions. It allows for appropriate selection of the number of patches for each geometry variable so as to ensure reliability of the optimization process while maintaining its low cost. The importance of this procedure is demonstrated by comparing it with uniform patch dimensions.

Towards robust algorithms for current deposition and dynamic load-balancing in a GPU particle in cell code

NASA Astrophysics Data System (ADS)

Rossi, Francesco; Londrillo, Pasquale; Sgattoni, Andrea; Sinigardi, Stefano; Turchetti, Giorgio

2012-12-01

We present `jasmine', an implementation of a fully relativistic, 3D, electromagnetic Particle-In-Cell (PIC) code, capable of running simulations in various laser plasma acceleration regimes on Graphics-Processing-Units (GPUs) HPC clusters. Standard energy/charge preserving FDTD-based algorithms have been implemented using double precision and quadratic (or arbitrary sized) shape functions for the particle weighting. When porting a PIC scheme to the GPU architecture (or, in general, a shared memory environment), the particle-to-grid operations (e.g. the evaluation of the current density) require special care to avoid memory inconsistencies and conflicts. Here we present a robust implementation of this operation that is efficient for any number of particles per cell and particle shape function order. Our algorithm exploits the exposed GPU memory hierarchy and avoids the use of atomic operations, which can hurt performance especially when many particles lay on the same cell. We show the code multi-GPU scalability results and present a dynamic load-balancing algorithm. The code is written using a python-based C++ meta-programming technique which translates in a high level of modularity and allows for easy performance tuning and simple extension of the core algorithms to various simulation schemes.

A stochastic approach to uncertainty in the equations of MHD kinematics

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

Phillips, Edward G., E-mail: egphillips@math.umd.edu; Elman, Howard C., E-mail: elman@cs.umd.edu

2015-03-01

The magnetohydrodynamic (MHD) kinematics model describes the electromagnetic behavior of an electrically conducting fluid when its hydrodynamic properties are assumed to be known. In particular, the MHD kinematics equations can be used to simulate the magnetic field induced by a given velocity field. While prescribing the velocity field leads to a simpler model than the fully coupled MHD system, this may introduce some epistemic uncertainty into the model. If the velocity of a physical system is not known with certainty, the magnetic field obtained from the model may not be reflective of the magnetic field seen in experiments. Additionally, uncertaintymore » in physical parameters such as the magnetic resistivity may affect the reliability of predictions obtained from this model. By modeling the velocity and the resistivity as random variables in the MHD kinematics model, we seek to quantify the effects of uncertainty in these fields on the induced magnetic field. We develop stochastic expressions for these quantities and investigate their impact within a finite element discretization of the kinematics equations. We obtain mean and variance data through Monte Carlo simulation for several test problems. Toward this end, we develop and test an efficient block preconditioner for the linear systems arising from the discretized equations.« less

Androgynous, Reconfigurable Closed Loop Feedback Controlled Low Impact Docking System With Load Sensing Electromagnetic Capture Ring

NASA Technical Reports Server (NTRS)

Lewis, James L. (Inventor); Carroll, Monty B. (Inventor); Morales, Ray H. (Inventor); Le, Thang D. (Inventor)

2002-01-01

The present invention relates to a fully androgynous, reconfigurable closed loop feedback controlled low impact docking system with load sensing electromagnetic capture ring. The docking system of the present invention preferably comprises two Docking- assemblies, each docking assembly comprising a load sensing ring having an outer face, one of more electromagnets, one or more load cells coupled to said load sensing ring. The docking assembly further comprises a plurality of actuator arms coupled to said load sensing ring and capable of dynamically adjusting the orientation of said load sensing ring and a reconfigurable closed loop control system capable of analyzing signals originating from said plurality of load cells and of outputting real time control for each of the actuators. The docking assembly of the present invention incorporates an active load sensing system to automatically dynamically adjust the load sensing ring during capture instead of requiring significant force to push and realign the ring.

Fielding a current idea: exploring the public health impact of electromagnetic radiation.

PubMed

Genuis, Stephen J

2008-02-01

Several publications in the scientific literature have raised concern about the individual and public health impact of adverse non-ionizing radiation (a-NIR) from electromagnetic field (EMF) exposure emanating from certain power, electrical and wireless devices commonly found in the home, workplace, school and community. Despite the many challenges in establishing irrefutable scientific proof of harm and the various gaps in elucidating the precise mechanisms of harm, epidemiological analyses continue to suggest considerable potential for injury and affliction as a result of a-NIR exposure. As environmental health has not been emphasized in medical education, some clinicians are not fully aware of possible EMF-related health problems and, as a result, manifestations of a-NIR may remain misdiagnosed and ineffectually managed. It is important for physicians and public health officials to be aware of the fundamental science and clinical implications of EMF exposure. A review of the scientific literature relating to the link between electromagnetic radiation and human health, several public health recommendations, and four case histories are presented for consideration.

Global fully kinetic models of planetary magnetospheres with iPic3D

NASA Astrophysics Data System (ADS)

Gonzalez, D.; Sanna, L.; Amaya, J.; Zitz, A.; Lembege, B.; Markidis, S.; Schriver, D.; Walker, R. J.; Berchem, J.; Peng, I. B.; Travnicek, P. M.; Lapenta, G.

2016-12-01

We report on the latest developments of our approach to model planetary magnetospheres, mini magnetospheres and the Earth's magnetosphere with the fully kinetic, electromagnetic particle in cell code iPic3D. The code treats electrons and multiple species of ions as full kinetic particles. We review: 1) Why a fully kinetic model and in particular why kinetic electrons are needed for capturing some of the most important aspects of the physics processes of planetary magnetospheres. 2) Why the energy conserving implicit method (ECIM) in its newest implementation [1] is the right approach to reach this goal. We consider the different electron scales and study how the new IECIM can be tuned to resolve only the electron scales of interest while averaging over the unresolved scales preserving their contribution to the evolution. 3) How with modern computing planetary magnetospheres, mini magnetosphere and eventually Earth's magnetosphere can be modeled with fully kinetic electrons. The path from petascale to exascale for iPiC3D is outlined based on the DEEP-ER project [2], using dynamic allocation of different processor architectures (Xeon and Xeon Phi) and innovative I/O technologies.Specifically results from models of Mercury are presented and compared with MESSENGER observations and with previous hybrid (fluid electrons and kinetic ions) simulations. The plasma convection around the planets includes the development of hydrodynamic instabilities at the flanks, the presence of the collisionless shocks, the magnetosheath, the magnetopause, reconnection zones, the formation of the plasma sheet and the magnetotail, and the variation of ion/electron plasma flows when crossing these frontiers. Given the full kinetic nature of our approach we focus on detailed particle dynamics and distribution at locations that can be used for comparison with satellite data. [1] Lapenta, G. (2016). Exactly Energy Conserving Implicit Moment Particle in Cell Formulation. arXiv preprint arXiv:1602.06326.[2] www.deep-er.eu

Magnetized Mini-Disk Simulations about Binary Black Holes

NASA Astrophysics Data System (ADS)

Noble, Scott; Bowen, Dennis B.; d'Ascoli, Stephane; Mewes, Vassilios; Campanelli, Manuela; Krolik, Julian

2018-01-01

Accretion disks around supermassive binary black holes offer a rare opportunity to probe the strong-field limit of dynamical gravity by using the ambient matter as a lighthouse. Accurate simulations of these systems using a variety of configurations will be critical to interpreting future observations of them. We have performed the first 3-d general relativistic magnetohydrodynamic simulations of mini-disks about a pair of equal mass black holes in the inspiral regime of their orbit. In this talk, we will present our latest results of 3-d general relativistic magnetohydrodynamic supercomputer simulations of accreting binary black holes during the post-Newtonian inspiral phase of their evolution. The goal of our work is to explore whether these systems provide a unique means to identify and characterize them with electromagnetic observations. We will provide a brief summary of the known electromagnetic signatures, in particular spectra and images obtained from post-process ray-tracing calculations of our simulation data. We will also provide a context for our results and describe our future avenues of exploration.

Spatio-temporal evolution of the non-resonant instability in shock precursors of young supernova remnants

NASA Astrophysics Data System (ADS)

Kobzar, Oleh; Niemiec, Jacek; Pohl, Martin; Bohdan, Artem

2017-08-01

A non-resonant cosmic ray (CR) current-driven instability may operate in the shock precursors of young supernova remnants and be responsible for magnetic-field amplification, plasma heating and turbulence. Earlier simulations demonstrated magnetic-field amplification, and in kinetic studies a reduction of the relative drift between CRs and thermal plasma was observed as backreaction. However, all published simulations used periodic boundary conditions, which do not account for mass conservation in decelerating flows and only allow the temporal development to be studied. Here we report results of fully kinetic particle-in-cell simulations with open boundaries that permit inflow of plasma on one side of the simulation box and outflow at the other end, hence allowing an investigation of both the temporal and the spatial development of the instability. Magnetic-field amplification proceeds as in studies with periodic boundaries and, observed here for the first time, the reduction of relative drifts causes the formation of a shock-like compression structure at which a fraction of the plasma ions are reflected. Turbulent electric field generated by the non-resonant instability inelastically scatters CRs, modifying and anisotropizing their energy distribution. Spatial CR scattering is compatible with Bohm diffusion. Electromagnetic turbulence leads to significant non-adiabatic heating of the background plasma maintaining bulk equipartition between ions and electrons. The highest temperatures are reached at sites of large-amplitude electrostatic fields. Ion spectra show supra-thermal tails resulting from stochastic scattering in the turbulent electric field. Together, these modifications in the plasma flow will affect the properties of the shock and particle acceleration there.

Development of an electromechanical principle for wet and dry milling

NASA Astrophysics Data System (ADS)

Halbedel, Bernd; Kazak, Oleg

2018-05-01

The paper presents a novel electromechanical principle for wet and dry milling of different materials, in which the milling beads are moved under a time- and local-variable magnetic field. A possibility to optimize the milling process in such a milling machine by simulation of the vector gradient distribution of the electromagnetic field in the process room is presented. The mathematical model and simulation methods based on standard software packages are worked out. The results of numerical simulations and experimental measurements of the electromagnetic field in the working chamber of a developed and manufactured laboratory plant correlate well with each other. Using the obtained operating parameters, dry milling experiments with crushed cement clinker and wet milling experiments of organic agents in the laboratory plant are performed and the results are discussed here.

A Numerical Simulation and Statistical Modeling of High Intensity Radiated Fields Experiment Data

NASA Technical Reports Server (NTRS)

Smith, Laura J.

2004-01-01

Tests are conducted on a quad-redundant fault tolerant flight control computer to establish upset characteristics of an avionics system in an electromagnetic field. A numerical simulation and statistical model are described in this work to analyze the open loop experiment data collected in the reverberation chamber at NASA LaRC as a part of an effort to examine the effects of electromagnetic interference on fly-by-wire aircraft control systems. By comparing thousands of simulation and model outputs, the models that best describe the data are first identified and then a systematic statistical analysis is performed on the data. All of these efforts are combined which culminate in an extrapolation of values that are in turn used to support previous efforts used in evaluating the data.

High-frequency electromagnetic scarring in three-dimensional axisymmetric convex cavities

DOE PAGES

Warne, Larry K.; Jorgenson, Roy E.

2016-04-13

Here, this article examines the localization of high-frequency electromagnetic fields in three-dimensional axisymmetric cavities along periodic paths between opposing sides of the cavity. When these orbits lead to unstable localized modes, they are known as scars. This article treats the case where the opposing sides, or mirrors, are convex. Particular attention is focused on the normalization through the electromagnetic energy theorem. Both projections of the field along the scarred orbit as well as field point statistics are examined. Statistical comparisons are made with a numerical calculation of the scars run with an axisymmetric simulation.

Compact electromagnetic bandgap structures for notch band in ultra-wideband applications.

PubMed

Rotaru, Mihai; Sykulski, Jan

2010-01-01

This paper introduces a novel approach to create notch band filters in the front-end of ultra-wideband (UWB) communication systems based on electromagnetic bandgap (EBG) structures. The concept presented here can be implemented in any structure that has a microstrip in its configuration. The EBG structure is first analyzed using a full wave electromagnetic solver and then optimized to work at WLAN band (5.15-5.825 GHz). Two UWB passband filters are used to demonstrate the applicability and effectiveness of the novel EBG notch band feature. Simulation results are provided for two cases studied.

Compact Electromagnetic Bandgap Structures for Notch Band in Ultra-Wideband Applications

PubMed Central

Rotaru, Mihai; Sykulski, Jan

2010-01-01

This paper introduces a novel approach to create notch band filters in the front-end of ultra-wideband (UWB) communication systems based on electromagnetic bandgap (EBG) structures. The concept presented here can be implemented in any structure that has a microstrip in its configuration. The EBG structure is first analyzed using a full wave electromagnetic solver and then optimized to work at WLAN band (5.15–5.825 GHz). Two UWB passband filters are used to demonstrate the applicability and effectiveness of the novel EBG notch band feature. Simulation results are provided for two cases studied. PMID:22163430

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.

The impact of electromagnetic radiation of different parameters on platelet oxygen metabolism - in vitro studies.

PubMed

Lewicka, Małgorzata; Henrykowska, Gabriela A; Pacholski, Krzysztof; Szczęsny, Artur; Dziedziczak-Buczyńska, Maria; Buczyński, Andrzej

2015-01-01

Electromagnetic radiation emitted by a variety of devices, e.g. cell phones, computers and microwaves, interacts with the human body in many ways. Research studies carried out in the last few decades have not yet resolved the issue of the effect of this factor on the human body and many questions are left without an unequivocal answer. Various biological and health-related effects have not been fully recognized. Thus further studies in this area are justified. A comparison of changes within catalase enzymatic activity and malondialdehyde concentration arising under the influence of the electromagnetic radiation emitted by car electronics, equipment used in physiotherapy and LCD monitors. The suspension of human blood platelets at a concentration of 1 × 109/0.001 dm 3, obtained from whole blood by manual apheresis, was the study material. Blood platelets were exposed to an electromagnetic field for 30 min in a laboratory stand designed for the reconstruction of the electromagnetic radiation generated by car electronics, physiotherapy equipment and LCD monitors. The changes in catalase activity and malondialdehyde concentration were investigated after the exposure and compared to the control values (unexposed material). An increase in catalase activity and malondialdehyde concentration was observed after 30 min exposure of platelets to EMF regardless of the radiation source. The most significant changes determining the degree of oxidative stress were observed after exposure to the EMF generated by car electronics. The low frequency electromagnetic fields generated by car electronics, physiotherapy equipment and LCD monitors may be a cause of oxidative stress in the human body and may lead to free radical diseases.

The electromagnetic bio-field: clinical experiments and interferences

PubMed Central

Burnei, G; Hodorogea, D; Georgescu, I; Gavriliu, Ş; Drăghici, I; Dan, D; Vlad, C; Drăghici, L

2012-01-01

Introduction: One of the most important factors is the technical and scientifically rapid development that is continually modifying the world we live in and polluting it with electromagnetic radiations. A functional and structural influence of magnetic and electromagnetic field on living organisms is presented in the literature by many performed experiments. Material and methods: The notion of bio-field represents the electromagnetic field generated by the bio-structures, not only in their normal physiological activities but also in their pathological states. There is a tight interdependency between the bio-field and the bio-structure, which respects the primary notion of an electromagnetic field given by the Maxwell-Faraday laws, in which, the electromagnetic phenomena are simplified to the field variations. These variations can be expressed in a coherent differential equation system that bounds the field vectors to different space points at different time moments. Results: The living organisms cannot contain electrostatic and magneto-static fields due to the intense activity of the bio-structures. The biochemical reactions that have high rhythms and speeds always impose the electrodynamics character of the biologic field that also corresponds to the stability of the protein molecule that can be explained only through a dynamic way. The existent energy is not considered an exciting agent, and it does not lead to any effects. Conclusions: The parameters of these elementary bio-fields cannot yet be fully known due to technical reasons. The biological structures are very complex ones and undergo continuous dynamical activity. That is why the calculus model should be related to the constant dynamics, nowadays being very difficult to express. PMID:22802878

The electromagnetic bio-field: clinical experiments and interferences.

PubMed

Burnei, G; Hodorogea, D; Georgescu, I; Gavriliu, Ş; Drăghici, I; Dan, D; Vlad, C; Drăghici, L

2012-06-12

One of the most important factors is the technical and scientifically rapid development that is continually modifying the world we live in and polluting it with electromagnetic radiations. A functional and structural influence of magnetic and electromagnetic field on living organisms is presented in the literature by many performed experiments. The notion of bio-field represents the electromagnetic field generated by the bio-structures, not only in their normal physiological activities but also in their pathological states. There is a tight interdependency between the bio-field and the bio-structure, which respects the primary notion of an electromagnetic field given by the Maxwell-Faraday laws, in which, the electromagnetic phenomena are simplified to the field variations. These variations can be expressed in a coherent differential equation system that bounds the field vectors to different space points at different time moments. The living organisms cannot contain electrostatic and magneto-static fields due to the intense activity of the bio-structures. The biochemical reactions that have high rhythms and speeds always impose the electrodynamics character of the biologic field that also corresponds to the stability of the protein molecule that can be explained only through a dynamic way. The existent energy is not considered an exciting agent, and it does not lead to any effects. The parameters of these elementary bio-fields cannot yet be fully known due to technical reasons. The biological structures are very complex ones and undergo continuous dynamical activity. That is why the calculus model should be related to the constant dynamics, nowadays being very difficult to express.

Addendum to `numerical modeling of an 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.; Abraham, J.D.

2000-01-01

Two numerical models to simulate an enhanced very early time electromagnetic (VETEM) prototype system that is used for buried-object detection and environmental problems are presented. In the first model, the transmitting and receiving loop antennas accurately analyzed using the method of moments (MoM), and then conjugate gradient (CG) methods with the fast Fourier transform (FFT) are utilized to investigate the scattering from buried conducting plates. In the second model, two magnetic dipoles are used to replace the transmitter and receiver. Both the theory and formulation are correct and the simulation results for the primary magnetic field and the reflected magnetic field are accurate.

Combined electromagnetic and photoreaction modeling of CLD-1 photobleaching in polymer microring resonators

NASA Astrophysics Data System (ADS)

Huang, Yanyi; Poon, Joyce K. S.; Liang, Wei; Yariv, Amnon; Zhang, Cheng; Dalton, Larry R.

2005-08-01

By combining a solid-state photoreaction model with the modal solutions of an optical waveguide, we simulate the refractive index change due to the photobleaching of CLD-1 chromophores in an amorphous polycarbonate microring resonator. The simulation agrees well with experimental results. The photobleaching quantum efficiency of the CLD-1 chromophores is determined to be 0.65%. The combined modeling of the electromagnetic wave propagation and photoreaction precisely illustrates the spatial and temporal evolution of the optical properties of the polymer material as manifested in the refractive index and their effects on the modal and physical properties of the optical devices.

Progress on the Multiphysics Capabilities of the Parallel Electromagnetic ACE3P Simulation Suite

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

Kononenko, Oleksiy

2015-03-26

ACE3P is a 3D parallel simulation suite that is being developed at SLAC National Accelerator Laboratory. Effectively utilizing supercomputer resources, ACE3P has become a key tool for the coupled electromagnetic, thermal and mechanical research and design of particle accelerators. Based on the existing finite-element infrastructure, a massively parallel eigensolver is developed for modal analysis of mechanical structures. It complements a set of the multiphysics tools in ACE3P and, in particular, can be used for the comprehensive study of microphonics in accelerating cavities ensuring the operational reliability of a particle accelerator.

Modeling and Simulation of Upset-Inducing Disturbances for Digital Systems in an Electromagnetic Reverberation Chamber

NASA Technical Reports Server (NTRS)

Torres-Pomales, Wilfredo

2014-01-01

This report describes a modeling and simulation approach for disturbance patterns representative of the environment experienced by a digital system in an electromagnetic reverberation chamber. The disturbance is modeled by a multi-variate statistical distribution based on empirical observations. Extended versions of the Rejection Samping and Inverse Transform Sampling techniques are developed to generate multi-variate random samples of the disturbance. The results show that Inverse Transform Sampling returns samples with higher fidelity relative to the empirical distribution. This work is part of an ongoing effort to develop a resilience assessment methodology for complex safety-critical distributed systems.

RELATIVISTIC CYCLOTRON INSTABILITY IN ANISOTROPIC PLASMAS

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

López, Rodrigo A.; Moya, Pablo S.; Muñoz, Víctor

2016-11-20

A sufficiently large temperature anisotropy can sometimes drive various types of electromagnetic plasma micro-instabilities, which can play an important role in the dynamics of relativistic pair plasmas in space, astrophysics, and laboratory environments. Here, we provide a detailed description of the cyclotron instability of parallel propagating electromagnetic waves in relativistic pair plasmas on the basis of a relativistic anisotropic distribution function. Using plasma kinetic theory and particle-in-cell simulations, we study the influence of the relativistic temperature and the temperature anisotropy on the collective and noncollective modes of these plasmas. Growth rates and dispersion curves from the linear theory show amore » good agreement with simulations results.« less

The method of impedance transformation for electromagnetic waves propagating in one-dimension plasma photonic crystal

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

Yao, Jingfeng; Yuan, Chengxun, E-mail: yuancx@hit.edu.cn, E-mail: zhouzx@hit.edu.cn; Gao, Ruilin

2016-08-15

This study focuses on the transmission of normal-incidence electromagnetic waves in one-dimensional plasma photonic crystals. Using the Maxwell's equations in a medium, a method that is based on the concept of impendence is employed to perform the simulation. The accuracy of the method was evaluated by simulating a one-layer plasma and conventional photonic crystal. In frequency-domain, the transmission and reflection coefficients in the unmagnetized plasma photonic crystal were calculated, and the influence factors on plasma photonic crystals including dielectric constants of dielectric, spatial period, filling factor, plasma frequency, and collision frequency were studied.

Study on the characteristics of multi-infeed HVDC

NASA Astrophysics Data System (ADS)

Li, Ming; Song, Xinli; Liu, Wenzhuo; Xiang, Yinxing; Zhao, Shutao; Su, Zhida; Meng, Hang

2017-09-01

China has built more than ten HVDC transmission projects in recent years [1]. Now, east China has formed a multi-HVDC feed pattern grid. It is imminent to study the interaction of the multi-HVDC and the characteristics of it. In this paper, an electromechanical-electromagnetic hybrid model is built with electromechanical data of a certain power network. We use electromagnetic models to simulate the HVDC section and electromechanical models simulate the AC power network [2]. In order to study the characteristics of the grid, this paper adds some faults to the line and analysed the fault characteristics. At last give analysis of the fault characteristics.

Kassiopeia: a modern, extensible C++ particle tracking package

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

Furse, Daniel; Groh, Stefan; Trost, Nikolaus

The Kassiopeia particle tracking framework is an object-oriented software package using modern C++ techniques, written originally to meet the needs of the KATRIN collaboration. Kassiopeia features a new algorithmic paradigm for particle tracking simulations which targets experiments containing complex geometries and electromagnetic fields, with high priority put on calculation efficiency, customizability, extensibility, and ease-of-use for novice programmers. To solve Kassiopeia's target physics problem the software is capable of simulating particle trajectories governed by arbitrarily complex differential equations of motion, continuous physics processes that may in part be modeled as terms perturbing that equation of motion, stochastic processes that occur inmore » flight such as bulk scattering and decay, and stochastic surface processes occurring at interfaces, including transmission and reflection effects. This entire set of computations takes place against the backdrop of a rich geometry package which serves a variety of roles, including initialization of electromagnetic field simulations and the support of state-dependent algorithm-swapping and behavioral changes as a particle's state evolves. Thanks to the very general approach taken by Kassiopeia it can be used by other experiments facing similar challenges when calculating particle trajectories in electromagnetic fields. It is publicly available at https://github.com/KATRIN-Experiment/Kassiopeia.« less

A Capsule-Type Electromagnetic Acoustic Transducer for Fast Screening of External Corrosion in Nonmagnetic Pipes.

PubMed

Li, Yong; Cai, Rui; Yan, Bei; Zainal Abidin, Ilham Mukriz; Jing, Haoqing; Wang, Yi

2018-05-28

For fuel transmission and structural strengthening, small-diameter pipes of nonmagnetic materials are extensively adopted in engineering fields including aerospace, energy, transportation, etc. However, the hostile and corrosive environment leaves them vulnerable to external corrosion which poses a severe threat to structural integrity of pipes. Therefore, it is imperative to nondestructively detect and evaluate the external corrosion in nonmagnetic pipes. In light of this, a capsule-type Electromagnetic Acoustic Transducer (EMAT) for in-situ nondestructive evaluation of nonmagnetic pipes and fast screening of external corrosion is proposed in this paper. A 3D hybrid model for efficient prediction of responses from the proposed transducer to external corrosion is established. Closed-form expressions of field quantities of electromagnetics and EMAT signals are formulated. Simulations based on the hybrid model indicate feasibility of the proposed transducer in detection and evaluation of external corrosion in nonmagnetic pipes. In parallel, experiments with the fabricated transducer have been carried out. Experimental results are supportive of the conclusion drawn from simulations. The investigation via simulations and experiments implies that the proposed capsule-type EMAT is capable of fast screening of external corrosion, which is beneficial to the in-situ nondestructive evaluation of small-diameter nonmagnetic pipes.

Variational formulation of macroparticle models for electromagnetic plasma simulations

DOE PAGES

Stamm, Alexander B.; Shadwick, Bradley A.; Evstatiev, Evstati G.

2014-06-01

A variational method is used to derive a self-consistent macroparticle model for relativistic electromagnetic kinetic plasma simulations. Extending earlier work, discretization of the electromagnetic Low Lagrangian is performed via a reduction of the phase-space distribution function onto a collection of finite-sized macroparticles of arbitrary shape and discretization of field quantities onto a spatial grid. This approach may be used with lab frame coordinates or moving window coordinates; the latter can greatly improve computational efficiency for studying some types of laser-plasma interactions. The primary advantage of the variational approach is the preservation of Lagrangian symmetries, which in our case leads tomore » energy conservation and thus avoids difficulties with grid heating. In addition, this approach decouples particle size from grid spacing and relaxes restrictions on particle shape, leading to low numerical noise. The variational approach also guarantees consistent approximations in the equations of motion and is amenable to higher order methods in both space and time. We restrict our attention to the 1.5-D case (one coordinate and two momenta). Lastly, simulations are performed with the new models and demonstrate energy conservation and low noise.« less

Kassiopeia: a modern, extensible C++ particle tracking package

DOE PAGES

Furse, Daniel; Groh, Stefan; Trost, Nikolaus; ...

2017-05-16

The Kassiopeia particle tracking framework is an object-oriented software package using modern C++ techniques, written originally to meet the needs of the KATRIN collaboration. Kassiopeia features a new algorithmic paradigm for particle tracking simulations which targets experiments containing complex geometries and electromagnetic fields, with high priority put on calculation efficiency, customizability, extensibility, and ease-of-use for novice programmers. To solve Kassiopeia's target physics problem the software is capable of simulating particle trajectories governed by arbitrarily complex differential equations of motion, continuous physics processes that may in part be modeled as terms perturbing that equation of motion, stochastic processes that occur inmore » flight such as bulk scattering and decay, and stochastic surface processes occurring at interfaces, including transmission and reflection effects. This entire set of computations takes place against the backdrop of a rich geometry package which serves a variety of roles, including initialization of electromagnetic field simulations and the support of state-dependent algorithm-swapping and behavioral changes as a particle's state evolves. Thanks to the very general approach taken by Kassiopeia it can be used by other experiments facing similar challenges when calculating particle trajectories in electromagnetic fields. It is publicly available at https://github.com/KATRIN-Experiment/Kassiopeia.« less

Kassiopeia: a modern, extensible C++ particle tracking package

NASA Astrophysics Data System (ADS)

Furse, Daniel; Groh, Stefan; Trost, Nikolaus; Babutzka, Martin; Barrett, John P.; Behrens, Jan; Buzinsky, Nicholas; Corona, Thomas; Enomoto, Sanshiro; Erhard, Moritz; Formaggio, Joseph A.; Glück, Ferenc; Harms, Fabian; Heizmann, Florian; Hilk, Daniel; Käfer, Wolfgang; Kleesiek, Marco; Leiber, Benjamin; Mertens, Susanne; Oblath, Noah S.; Renschler, Pascal; Schwarz, Johannes; Slocum, Penny L.; Wandkowsky, Nancy; Wierman, Kevin; Zacher, Michael

2017-05-01

The Kassiopeia particle tracking framework is an object-oriented software package using modern C++ techniques, written originally to meet the needs of the KATRIN collaboration. Kassiopeia features a new algorithmic paradigm for particle tracking simulations which targets experiments containing complex geometries and electromagnetic fields, with high priority put on calculation efficiency, customizability, extensibility, and ease-of-use for novice programmers. To solve Kassiopeia's target physics problem the software is capable of simulating particle trajectories governed by arbitrarily complex differential equations of motion, continuous physics processes that may in part be modeled as terms perturbing that equation of motion, stochastic processes that occur in flight such as bulk scattering and decay, and stochastic surface processes occurring at interfaces, including transmission and reflection effects. This entire set of computations takes place against the backdrop of a rich geometry package which serves a variety of roles, including initialization of electromagnetic field simulations and the support of state-dependent algorithm-swapping and behavioral changes as a particle’s state evolves. Thanks to the very general approach taken by Kassiopeia it can be used by other experiments facing similar challenges when calculating particle trajectories in electromagnetic fields. It is publicly available at https://github.com/KATRIN-Experiment/Kassiopeia.

Reference Frames and the Physical Gravito-Electromagnetic Analogy

NASA Astrophysics Data System (ADS)

Costa, Luis Filipe P. O.; Herdeiro, C. A. R.

2009-05-01

The interest on the physical analogies between General Relativity and Electromagnetism has been revived by the recent Gravity Probe-B and the upcoming Lares missions, aiming to measure the so-called gravito-magnetic effects. These effects are presently believed to be at the origin of observed jets in quasars, galactic nuclei, neutron stars and black holes, as well as the precession of black holes' accretion disks. Gravitomagnetism has been studied mainly in a first order approximation ( e.g. [arXiv:gr-qc/0207065]) which, making use of certain similarities between linearized gravity and electromagnetism, applies intuition and well known results from electromagnetic phenomena to the description of the less familiar gravitational ones. However, there is no consensus at present on the limit of validity of such approach. Using a new exact approach based on tidal tensors [Phys. Rev. D 78, 024021 (2008)], we show that the existence of the aforementioned similarities depends crucially on the reference frame. Whereas a stationary observer will find remarkable similarities between the gravitational and electromagnetic interactions, if the fields are not stationary in the observer's rest frame, however, the two interactions differ significantly, so that the gravito-electromagnetic equations commonly found in literature are no longer valid. The tidal tensor formalism allows for a comparison between gravity and electromagnetism in terms of quantities common to both theories (tidal forces), making transparent both the similarities and key differences between the two interactions. It also unveils a new analogy based on exact, covariant, and fully general equations, which allows to extend the intuition from electromagnetism to the understanding of non-linear gravitational phenomena, such as the spin interaction between two celestial bodies, and Hawking's [Phys Rev. Lett. 26, 1344 (1971)] spin-dependent upper bound for the energy released by gravitational radiation when two black holes collide. Funded by Fundação para a Ciència e a Tecnologia, Grant SFRH/BD/41370/2007

Change in spatial coherence of light on refraction and on reflection.

PubMed

Lahiri, Mayukh; Wolf, Emil

2013-06-01

A theory of refraction and reflection of partially coherent electromagnetic beams has been recently developed. In this paper, we apply it to study the change in spatial coherence caused by refraction and by reflection more fully. By considering a Gaussian Schell-model beam, we show that the change is, in general, dependent on the angle of incidence.

Ohm's law in the fast lane: general relatiivistic charge dynamics

NASA Technical Reports Server (NTRS)

Meier, D.

2004-01-01

Fully relativistic and causal equations for the flow of charge in curved spacetime are derived. It is believed that this is the first set of equations to be published that correctly describes the flow of charge, as well as the evolution of the electromagnetic field, in highly dynamical relativistic environments on timescales much shorter than the collapse time (GM/c3).

Electromagnetic compatibility and safety design of a patient compliance-free, inductive implant charger.

PubMed

Theodoridis, Michael P; Mollov, Stefan V

2014-10-01

This article presents the design of a domestic, radiofrequency induction charger for implants toward compliance with the Federal Communications Commission safety and electromagnetic compatibility regulations. The suggested arrangement does not impose any patient compliance requirements other than the use of a designated bed for night sleep, and therefore can find a domestic use. The method can be applied to a number of applications; a rechargeable pacemaker is considered as a case study. The presented work has proven that it is possible to realize a fully compliant inductive charging system with minimal patient interaction, and has generated important information for consideration by the designers of inductive charging systems. Experimental results have verified the validity of the theoretical findings.

Strong-field adiabatic passage in the continuum: Electromagnetically induced transparency and stimulated Raman adiabatic passage

NASA Astrophysics Data System (ADS)

Eilam, A.; Shapiro, M.

2012-01-01

We present a fully quantum-mechanical theory of the mutual light-matter effects when two laser pulses interact with three discrete states coupled to a (quasi)continuum. Our formulation uses a single set of equations to describe the time dependence of the discrete and continuum populations, as well as pulse propagation in electromagnetically induced transparency (EIT) and stimulated Raman adiabatic passage (STIRAP) situations, for both weak and strong laser pulses. The theory gives a mechanistic picture of the “slowing down of light” and the state of spontaneously emitted photons during this process. Surprising features regarding the time dependence of material and radiative transients as well as limitations on quantum light storage and retrieval are unraveled.

Electromagnetic Effices from Impacts on Spacecraft

NASA Astrophysics Data System (ADS)

Close, Sigrid

2018-04-01

Hypervelocity micro particles, including meteoroids and space debris with masses < 1 ng, routinely impact spacecraft and create dense plasma that expands at the isothermal sound speed. This plasma, with a charge separation commensurate with different species mobilities, can produce a strong electromagnetic pulse (EMP) with a broad frequency spectrum. Subsequent plasma oscillations resulting from instabilities can also emit significant power and may be responsible for many reported satellite anomalies. We present theory and recent results from ground-based impact tests aimed at characterizing hypervelocity impact plasma and show that impact-produced radio frequency (RF) emissions occurred in frequencies ranging from VHF through L-band and that these emissions were highly correlated with fast (> 20 km/s) impacts that produced a fully ionized plasma.

The use of MR B+1 imaging for validation of FDTD electromagnetic simulations of human anatomies.

PubMed

Van den Berg, Cornelis A T; Bartels, Lambertus W; van den Bergen, Bob; Kroeze, Hugo; de Leeuw, Astrid A C; Van de Kamer, Jeroen B; Lagendijk, Jan J W

2006-10-07

In this study, MR B(+)(1) imaging is employed to experimentally verify the validity of FDTD simulations of electromagnetic field patterns in human anatomies. Measurements and FDTD simulations of the B(+)(1) field induced by a 3 T MR body coil in a human corpse were performed. It was found that MR B(+)(1) imaging is a sensitive method to measure the radiofrequency (RF) magnetic field inside a human anatomy with a precision of approximately 3.5%. A good correlation was found between the B(+)(1) measurements and FDTD simulations. The measured B(+)(1) pattern for a human pelvis consisted of a global, diagonal modulation pattern plus local B(+)(1) heterogeneties. It is believed that these local B(+)(1) field variations are the result of peaks in the induced electric currents, which could not be resolved by the FDTD simulations on a 5 mm(3) simulation grid. The findings from this study demonstrate that B(+)(1) imaging is a valuable experimental technique to gain more knowledge about the dielectric interaction of RF fields with the human anatomy.

Analysis of Waves in Space Plasma (WISP) near field simulation and experiment

NASA Technical Reports Server (NTRS)

Richie, James E.

1992-01-01

The WISP payload scheduler for a 1995 space transportation system (shuttle flight) will include a large power transmitter on board at a wide range of frequencies. The levels of electromagnetic interference/electromagnetic compatibility (EMI/EMC) must be addressed to insure the safety of the shuttle crew. This report is concerned with the simulation and experimental verification of EMI/EMC for the WISP payload in the shuttle cargo bay. The simulations have been carried out using the method of moments for both thin wires and patches to stimulate closed solids. Data obtained from simulation is compared with experimental results. An investigation of the accuracy of the modeling approach is also included. The report begins with a description of the WISP experiment. A description of the model used to simulate the cargo bay follows. The results of the simulation are compared to experimental data on the input impedance of the WISP antenna with the cargo bay present. A discussion of the methods used to verify the accuracy of the model is shown to illustrate appropriate methods for obtaining this information. Finally, suggestions for future work are provided.

Monte Carlo closure for moment-based transport schemes in general relativistic radiation hydrodynamic simulations

NASA Astrophysics Data System (ADS)

Foucart, Francois

2018-04-01

General relativistic radiation hydrodynamic simulations are necessary to accurately model a number of astrophysical systems involving black holes and neutron stars. Photon transport plays a crucial role in radiatively dominated accretion discs, while neutrino transport is critical to core-collapse supernovae and to the modelling of electromagnetic transients and nucleosynthesis in neutron star mergers. However, evolving the full Boltzmann equations of radiative transport is extremely expensive. Here, we describe the implementation in the general relativistic SPEC code of a cheaper radiation hydrodynamic method that theoretically converges to a solution of Boltzmann's equation in the limit of infinite numerical resources. The algorithm is based on a grey two-moment scheme, in which we evolve the energy density and momentum density of the radiation. Two-moment schemes require a closure that fills in missing information about the energy spectrum and higher order moments of the radiation. Instead of the approximate analytical closure currently used in core-collapse and merger simulations, we complement the two-moment scheme with a low-accuracy Monte Carlo evolution. The Monte Carlo results can provide any or all of the missing information in the evolution of the moments, as desired by the user. As a first test of our methods, we study a set of idealized problems demonstrating that our algorithm performs significantly better than existing analytical closures. We also discuss the current limitations of our method, in particular open questions regarding the stability of the fully coupled scheme.

Microwave thermal ablation: Effects of tissue properties variations on predictive models for treatment planning.

PubMed

Lopresto, Vanni; Pinto, Rosanna; Farina, Laura; Cavagnaro, Marta

2017-08-01

Microwave thermal ablation (MTA) therapy for cancer treatments relies on the absorption of electromagnetic energy at microwave frequencies to induce a very high and localized temperature increase, which causes an irreversible thermal damage in the target zone. Treatment planning in MTA is based on experimental observations of ablation zones in ex vivo tissue, while predicting the treatment outcomes could be greatly improved by reliable numerical models. In this work, a fully dynamical simulation model is exploited to look at effects of temperature-dependent variations in the dielectric and thermal properties of the targeted tissue on the prediction of the temperature increase and the extension of the thermally coagulated zone. In particular, the influence of measurement uncertainty of tissue parameters on the numerical results is investigated. Numerical data were compared with data from MTA experiments performed on ex vivo bovine liver tissue at 2.45GHz, with a power of 60W applied for 10min. By including in the simulation model an uncertainty budget (CI=95%) of ±25% in the properties of the tissue due to inaccuracy of measurements, numerical results were achieved in the range of experimental data. Obtained results also showed that the specific heat especially influences the extension of the thermally coagulated zone, with an increase of 27% in length and 7% in diameter when a variation of -25% is considered with respect to the value of the reference simulation model. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

Hydraulic continuity and biological effects of low strength very low frequency electromagnetic waves: Case of microbial biofilm growth in water treatment.

PubMed

Gérard, Merlin; Noamen, Omri; Evelyne, Gonze; Eric, Valette; Gilles, Cauffet; Marc, Henry

2015-10-15

This study aims to elucidate the interactions between water, subjected to electromagnetic waves of very low frequency (VLF) (kHz) with low strength electromagnetic fields (3.5 mT inside the coils), and the development of microbial biofilms in this exposed water. Experimental results demonstrate that in water exposed to VLF electromagnetic waves, the biomass of biofilm is limited if hydraulic continuity is achieved between the electromagnetic generator and the biofilm media. The measured amount of the biofilm's biomass is approximately a factor two lower for exposed biofilm than the non-exposed biofilm. Measurements of electromagnetic fields in the air and simulations exhibit very low intensities of fields (<10 nT and 2 V/m) in the biofilm-exposed region at a distance of 1 m from the electromagnetic generator. Exposure to electric and magnetic fields of the quoted intensities cannot explain thermal and ionizing effects on the biofilm. A variable electrical potential with a magnitude close to 20 mV was detected in the tank in hydraulic continuity with the electromagnetic generator. The application of quantum field theory may help to explain the observed effects in this case. Copyright © 2015 Elsevier Ltd. All rights reserved.

16TH Annual Review of Progress in Applied Computational Electromagnetics of the Naval Postgraduate School, Monterey, CA. Volume I

DTIC Science & Technology

2000-03-24

Element Method for Designing Plasma Reactors" Leo Kempel, Paul Rummel, Tim Grotjohn and John Amrhein ............................................ 28...34Finite Element Method for Designing Plasma Reactors" Leo Kempel, Paul Rummel, Tim Grotjohn and John Amrhein...548 "lime-Domain Simulation of Electromagnetic Wave Propagation in a Magnetized Plasma" J. Paul , C. Christopoulos, and

Strong coupling in electromechanical computation

NASA Astrophysics Data System (ADS)

Füzi, János

2000-06-01

A method is presented to carry out simultaneously electromagnetic field and force computation, electrical circuit analysis and mechanical computation to simulate the dynamic operation of electromagnetic actuators. The equation system is solved by a predictor-corrector scheme containing a Powell error minimization algorithm which ensures that every differential equation (coil current, field strength rate, flux rate, speed of the keeper) is fulfilled within the same time step.

A multi-band, multi-level, multi-electron model for efficient FDTD simulations of electromagnetic interactions with semiconductor quantum wells

NASA Astrophysics Data System (ADS)

Ravi, Koustuban; Wang, Qian; Ho, Seng-Tiong

2015-08-01

We report a new computational model for simulations of electromagnetic interactions with semiconductor quantum well(s) (SQW) in complex electromagnetic geometries using the finite-difference time-domain method. The presented model is based on an approach of spanning a large number of electron transverse momentum states in each SQW sub-band (multi-band) with a small number of discrete multi-electron states (multi-level, multi-electron). This enables accurate and efficient two-dimensional (2-D) and three-dimensional (3-D) simulations of nanophotonic devices with SQW active media. The model includes the following features: (1) Optically induced interband transitions between various SQW conduction and heavy-hole or light-hole sub-bands are considered. (2) Novel intra sub-band and inter sub-band transition terms are derived to thermalize the electron and hole occupational distributions to the correct Fermi-Dirac distributions. (3) The terms in (2) result in an explicit update scheme which circumvents numerically cumbersome iterative procedures. This significantly augments computational efficiency. (4) Explicit update terms to account for carrier leakage to unconfined states are derived, which thermalize the bulk and SQW populations to a common quasi-equilibrium Fermi-Dirac distribution. (5) Auger recombination and intervalence band absorption are included. The model is validated by comparisons to analytic band-filling calculations, simulations of SQW optical gain spectra, and photonic crystal lasers.

A dual resonant rectilinear-to-rotary oscillation converter for low frequency broadband electromagnetic energy harvesting

NASA Astrophysics Data System (ADS)

Deng, Wei; Wang, Ya

2017-09-01

This paper reports a dual resonant rectilinear-to-rotary oscillation converter (RROC) for low frequency broadband electromagnetic energy harvesting from ambient vibrations. An approximate theoretical model has been established to integrate the electromechanical coupling into a comprehensive electromagnetic-dynamic model of the dual resonant RROC. Numerical simulation has proved the nature of dual resonances by revealing that both the rectilinear resonance and the rotary resonance could be achieved when the stand-alone rectilinear oscillator (RLO) and the stand-alone rotary oscillator (RTO) were excited independently. Simulation on the magnetically coupled RROC has also shown that the rectilinear resonance and the rotary resonance could be obtained simultaneously in the low-frequency region (2-14 Hz) with well-defined restoring torque (M r ) and the initial rotation angle of the RLO (ψ). The magnetic interaction patterns between the rectilinear and the RTOs have been categorized based on aforementioned simulation results. Both simulation and experimental results have demonstrated broadband output attributing from the dual resonances. Experimental results have also indicated that the RROC could have wide bandwidth in a much lower frequency region (2-8 Hz) even without the rotary resonance as long as the system parameters are carefully tuned. Parameter analysis on different values of M r and ψ are experimentally carried out to provide a quantitative guidance of designing the RROC to achieve an optimal power density.

Electromagnetic resonance in the asymmetric terahertz metamaterials with triangle microstructure

NASA Astrophysics Data System (ADS)

Xing, Yuanyuan; Zhang, Xiaoyu; Zhang, Qiang; Gu, Yanping; Qian, Yunan; Lin, Xingyue; Tang, Yunhai; Cheng, Xinli; Qin, Changfa; Shen, Jiaoyan; Zang, Taocheng; Ma, Chunlan

2018-05-01

We investigate terahertz transmission properties and electromagnetic resonance modes in the asymmetric triangle structures with the change of asymmetric distance and the direction of electric field. When the THz electric field is perpendicular to the split gap of triangle, the electric field can better excite the THz absorption in the triangle structures. Importantly, electromagnetically induced transparency (EIT) characteristics are observed in the triangle structures due to the destructive interference of the different excited modes. The distributions of electric field and surface current density simulated by finite difference time domain indicate that the bright mode is excited by the side of triangle structures and dark mode is excited by the gap-side of triangle. The present study is helpful to understand the electromagnetic resonance in the asymmetric triangular metamaterials.

Electromagnetic holographic sensitivity field of two-phase flow in horizontal wells

NASA Astrophysics Data System (ADS)

Zhang, Kuo; Wu, Xi-Ling; Yan, Jing-Fu; Cai, Jia-Tie

2017-03-01

Electromagnetic holographic data are characterized by two modes, suggesting that image reconstruction requires a dual-mode sensitivity field as well. We analyze an electromagnetic holographic field based on tomography theory and Radon inverse transform to derive the expression of the electromagnetic holographic sensitivity field (EMHSF). Then, we apply the EMHSF calculated by using finite-element methods to flow simulations and holographic imaging. The results suggest that the EMHSF based on the partial derivative of radius of the complex electric potential φ is closely linked to the Radon inverse transform and encompasses the sensitivities of the amplitude and phase data. The flow images obtained with inversion using EMHSF better agree with the actual flow patterns. The EMHSF overcomes the limitations of traditional single-mode sensitivity fields.

Multiple Frequency Contrast Source Inversion Method for Vertical Electromagnetic Profiling: 2D Simulation Results and Analyses

NASA Astrophysics Data System (ADS)

Li, Jinghe; Song, Linping; Liu, Qing Huo

2016-02-01

A simultaneous multiple frequency contrast source inversion (CSI) method is applied to reconstructing hydrocarbon reservoir targets in a complex multilayered medium in two dimensions. It simulates the effects of a salt dome sedimentary formation in the context of reservoir monitoring. In this method, the stabilized biconjugate-gradient fast Fourier transform (BCGS-FFT) algorithm is applied as a fast solver for the 2D volume integral equation for the forward computation. The inversion technique with CSI combines the efficient FFT algorithm to speed up the matrix-vector multiplication and the stable convergence of the simultaneous multiple frequency CSI in the iteration process. As a result, this method is capable of making quantitative conductivity image reconstruction effectively for large-scale electromagnetic oil exploration problems, including the vertical electromagnetic profiling (VEP) survey investigated here. A number of numerical examples have been demonstrated to validate the effectiveness and capacity of the simultaneous multiple frequency CSI method for a limited array view in VEP.

The simulation of electromagnetically driven strong Langmuir turbulence effect on the backscatter radiation from ionosphere

NASA Astrophysics Data System (ADS)

Kochetov, Andrey

2016-07-01

Numerical simulations of the dynamics of electromagnetic fields in a smoothly inhomogeneous nonlinear plasma layer in frameworks of the nonlinear Schrödinger equation with boundary conditions responsible for the pumping of the field in the layer by an incident wave and the inverse radiation losses supplemented the volume field dissipation due to the electromagnetic excitation of Langmuir turbulence are carried out. The effects of the threshold of non-linearity and it's evolution, of the threshold and saturation levels of dissipation in the vicinity of the wave reflection point on the features of the dynamics of reflection and absorption indexes are investigated. We consider the hard drive damping depending on the local field amplitude and hysteresis losses with different in several times "on" and "off" absorption thresholds as well. The dependence of the thresholds of the steady-state, periodic and chaotic regimes of plasma-wave interaction on the scenario of turbulence evolution is demonstrated. The results are compared with the experimental observations of Langmuir stage ionospheric modification.

Numerical Electromagnetics Simulations of the Leakage Through the Pump-out Holes in the DISC Electromagnetic Interference Shield

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

Brown, Jr., Charles G.; Cooper, Amy; Moore, Alastair S.

In order to prevent electromagnetic interference (EMI) from affecting the DISC diagnostic, an EMI shield was added. Figure 1 is a cross section from a CAD model of DISC and shows the EMI shield in situ. The shield is orange and at the top of the figure. Figure 2 is a drawing of just the EMI shield. The slit in the center of the EMI shield is covered by a metal mesh, which is not shown in this drawing. The small holes toward the base of the conical portion of the EMI shield are the pump-out holes, and the electromagneticmore » leakage through these holes is the subject of this report1. An alternate design for the EMI shield is considered in order to determine how to increase the EMI effectiveness of the pump-out holes in the shield without compromising the flow rate through the shield. Both the original and alternate designs are simulated and compared.« less

Large Eddy Simulations of Electromagnetic Braking Effects on Argon Bubble Transport and Capture in a Steel Continuous Casting Mold

NASA Astrophysics Data System (ADS)

Jin, Kai; Vanka, Surya P.; Thomas, Brian G.

2018-02-01

In continuous casting of steel, argon gas is often injected to prevent clogging of the nozzle, but the bubbles affect the flow pattern, and may become entrapped to form defects in the final product. Further, an electromagnetic field is frequently applied to induce a braking effect on the flow field and modify the inclusion transport. In this study, a previously validated GPU-based in-house code CUFLOW is used to investigate the effect of electromagnetic braking on turbulent flow, bubble transport, and capture. Well-resolved large eddy simulations are combined with two-way coupled Lagrangian computations of the bubbles. The drag coefficient on the bubbles is modified to account for the effects of the magnetic field. The distribution of the argon bubbles, capture, and escape rates, are presented and compared with and without the magnetic field. The bubble capture patterns are also compared with results of a previous RANS model as well as with plant measurements.

Large Eddy Simulations of Electromagnetic Braking Effects on Argon Bubble Transport and Capture in a Steel Continuous Casting Mold

NASA Astrophysics Data System (ADS)

Jin, Kai; Vanka, Surya P.; Thomas, Brian G.

2018-06-01

In continuous casting of steel, argon gas is often injected to prevent clogging of the nozzle, but the bubbles affect the flow pattern, and may become entrapped to form defects in the final product. Further, an electromagnetic field is frequently applied to induce a braking effect on the flow field and modify the inclusion transport. In this study, a previously validated GPU-based in-house code CUFLOW is used to investigate the effect of electromagnetic braking on turbulent flow, bubble transport, and capture. Well-resolved large eddy simulations are combined with two-way coupled Lagrangian computations of the bubbles. The drag coefficient on the bubbles is modified to account for the effects of the magnetic field. The distribution of the argon bubbles, capture, and escape rates, are presented and compared with and without the magnetic field. The bubble capture patterns are also compared with results of a previous RANS model as well as with plant measurements.

FDTD chiral brain tissue model for specific absorption rate determination under radiation from mobile phones at 900 and 1800 MHz

NASA Astrophysics Data System (ADS)

Zamorano, M.; Torres-Silva, H.

2006-04-01

A new electrodynamics model formed by chiral bioplasma, which represents the human head inner structure and makes it possible to analyse its behaviour when it is irradiated by a microwave electromagnetic field from cellular phones, is presented. The finite-difference time-domain (FDTD) numeric technique is used, which allows simulation of the electromagnetic fields, deduced with Maxwell's equations, and allows us to simulate the specific absorption rate (SAR). The results show the SAR behaviour as a function of the input power and the chirality factor. In considering the chiral brain tissue in the proposed human head model, the two more important conclusions of our work are the following: (a) the absorption of the electromagnetic fields from cellular phones is stronger, so the SAR coefficient is higher than that using the classical model, when values of the chiral factor are of order of 1; (b) 'inverse skin effect' shows up at 1800 MHz, with respect to a 900 MHz source.

Electromagnetic modelling of conductive or superconductive microstrip lines using spice as electromagnetic solver

NASA Astrophysics Data System (ADS)

Dinh, Thanh Vu; Cabon, Béatrice; Daoud, Nahla; Chilo, Jean

1992-11-01

This paper presents a simple and efficient method for calculating the propagating line parameters (actually, a microstrip one) and its magnetic fields, by simulating an original equivalent circuit with an electrical nodal simulator (SPICE). The losses in the normal conducting line (due to DC losses and to skin effect losses) and also in the superconducting one can be investigated. This allows us to integrate the electromagnetic solutions to the CAD softwares. Dans ce papier, une méthode simple et efficace pour calculer les paramètres de propagation d'une ligne microruban et les champs magnétiques qu'elle engendre est présentée; pour cela, nous simulons un circuit original équivalent à l'aide du simulateur nodal SPICE. Les pertes dans une ligne conductrice (pertes continues et par effet de peau) ainsi que dans une ligne supraconductrice peuvent être considérées. Les solutions électromagnétiques peuvent être intégrées dans les simulateurs de CAO.

New aspects of whistler waves driven by an electron beam studied by a 3-D electromagnetic code

NASA Technical Reports Server (NTRS)

Nishikawa, Ken-Ichi; Buneman, Oscar; Neubert, Torsten

1994-01-01

We have restudied electron beam driven whistler waves with a 3-D electromagnetic particle code. The simulation results show electromagnetic whistler wave emissions and electrostatic beam modes like those observed in the Spacelab 2 electron beam experiment. It has been suggested in the past that the spatial bunching of beam electrons associated with the beam mode may directly generate whistler waves. However, the simulation results indicate several inconsistencies with this picture: (1) whistler waves continue to be generated even after the beam mode space charge modulation looses its coherence, (2) the parallel (to the background magnetic field) wavelength of the whistler wave is longer than that of the beam instability, and (3) the parallel phase velocity of the whistler wave is smaller than that of the beam mode. The complex structure of the whistler waves in the vicinity of the beam suggest that the transverse motion (gyration) of the beam and background electrons is also involved in the generation of whistler waves.

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.

AC losses in horizontally parallel HTS tapes for possible wireless power transfer applications

NASA Astrophysics Data System (ADS)

Shen, Boyang; Geng, Jianzhao; Zhang, Xiuchang; Fu, Lin; Li, Chao; Zhang, Heng; Dong, Qihuan; Ma, Jun; Gawith, James; Coombs, T. A.

2017-12-01

This paper presents the concept of using horizontally parallel HTS tapes with AC loss study, and the investigation on possible wireless power transfer (WPT) applications. An example of three parallel HTS tapes was proposed, whose AC loss study was carried out both from experiment using electrical method; and simulation using 2D H-formulation on the FEM platform of COMSOL Multiphysics. The electromagnetic induction around the three parallel tapes was monitored using COMSOL simulation. The electromagnetic induction and AC losses generated by a conventional three turn coil was simulated as well, and then compared to the case of three parallel tapes with the same AC transport current. The analysis demonstrates that HTS parallel tapes could be potentially used into wireless power transfer systems, which could have lower total AC losses than conventional HTS coils.

Two-dimensional probabilistic inversion of plane-wave electromagnetic data: methodology, model constraints and joint inversion with electrical resistivity data

NASA Astrophysics Data System (ADS)

Rosas-Carbajal, Marina; Linde, Niklas; Kalscheuer, Thomas; Vrugt, Jasper A.

2014-03-01

Probabilistic inversion methods based on Markov chain Monte Carlo (MCMC) simulation are well suited to quantify parameter and model uncertainty of nonlinear inverse problems. Yet, application of such methods to CPU-intensive forward models can be a daunting task, particularly if the parameter space is high dimensional. Here, we present a 2-D pixel-based MCMC inversion of plane-wave electromagnetic (EM) data. Using synthetic data, we investigate how model parameter uncertainty depends on model structure constraints using different norms of the likelihood function and the model constraints, and study the added benefits of joint inversion of EM and electrical resistivity tomography (ERT) data. Our results demonstrate that model structure constraints are necessary to stabilize the MCMC inversion results of a highly discretized model. These constraints decrease model parameter uncertainty and facilitate model interpretation. A drawback is that these constraints may lead to posterior distributions that do not fully include the true underlying model, because some of its features exhibit a low sensitivity to the EM data, and hence are difficult to resolve. This problem can be partly mitigated if the plane-wave EM data is augmented with ERT observations. The hierarchical Bayesian inverse formulation introduced and used herein is able to successfully recover the probabilistic properties of the measurement data errors and a model regularization weight. Application of the proposed inversion methodology to field data from an aquifer demonstrates that the posterior mean model realization is very similar to that derived from a deterministic inversion with similar model constraints.

Coalescence of two current loops with a kink instability simulated by a three-dimensional electromagnetic particle code

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Sakai, J.-I.; Zhao, Jie; Neubert, T.; Buneman, Oscar

1994-01-01

We have studied the dynamics of a coalescence of current loops using three-dimensional electromagnetic (EM) particle simulation code. Our focus is the investigation of such kinetic processes as energy trasnfer, heating particles, and electromagnetic emissions associated with a current loop coalescence which cannot be studied by MHD simulations. First, the two loops undergo a pinching oscillation due to a pressure imbalance between the inside and outside of the current loop. During the pinching oscillation, a kinetic kink instability is excited and electrons in the loops are heated perpendicularly to an ambient magnetic field. Next, the two current loops collide and coalesce, while at the same time a helical structure grows further. Subsequently, the perturbed current, which is due to these helically bunched electrons, can drive a whistler instability. It should be noted in this case that the whistler wave is excited by the kinetic kink instability and not a beam instability. After the coalescence of two helical loops, tilting motions can be observed in the direction of left-hand rotation, and the helical structure will relax resulting in strong plasma heating mostly in the direction perpendicular to the ambient magnetic field. It is also shown that high-frequency electromagnetic waves can be emitted from the region where the two loops coalesce and propagate strongly in the direction of the electron drift velocity. These processes may be important in understanding heating mechansims for coronal loops as well as radio wave emission mechanisms from active regions of solar plasmas.

Simulation Methods for Optics and Electromagnetics in Complex Geometries and Extreme Nonlinear Regimes with Disparate Scales

DTIC Science & Technology

2014-09-30

software devel- oped with this project support. S1 Cork School 2013: I. UPPEcore Simulator design and usage, Simulation examples II. Nonlinear pulse...pulse propagation 08/28/13 — 08/02/13, University College Cork , Ireland S2 ACMS MURI School 2012: Computational Methods for Nonlinear PDEs describing

Whistler Observations on DEMETER Compared with Full Electromagnetic Wave Simulations

NASA Astrophysics Data System (ADS)

Compston, A. J.; Cohen, M.; Lehtinen, N. G.; Inan, U.; Linscott, I.; Said, R.; Parrot, M.

2014-12-01

Terrestrial Very Low Frequency (VLF) electromagnetic radiation, which strongly impacts the Van Allen radiation belt electron dynamics, is injected across the ionosphere into the Earth's plasmasphere from two primary sources: man-made VLF transmitters and lightning discharges. Numerical models of trans-ionospheric propagation of such waves remain unvalidated, and early models may have overestimated the absorption, hindering a comprehensive understanding of the global impact of VLF waves in the loss of radiation belt electrons. In an attempt to remedy the problem of a lack of accurate trans-ionospheric propagation models, we have used a full electromagnetic wave method (FWM) numerical code to simulate the propagation of lightning-generated whistlers into the magnetosphere and compared the results with whistlers observed on the DEMETER satellite and paired with lightning stroke data from the National Lightning Detection Network (NLDN). We have identified over 20,000 whistlers occuring in 14 different passes of DEMETER over the central United States during the summer of 2009, and 14,000 of those occured within the 2000 km x 2000 km simulation grid we used. As shown in the attached figure, which shows a histogram of the ratio of the simulated whistler energy to the measured whistler energy for the 14,000 whistlers we compared, the simulation tends to slightly underestimate the total whistler energy injected by about 5 dB. However, the simulation underestimates the DEMETER measurements more as one gets further from the source lightning stroke, so since the signal to noise ratio of more distant whistlers will be smaller, possibly additive noise in the DEMETER measurements (which of course is not accounted for in the model) may explain some of the observed discrepancy.

Electromagnetic tracking for abdominal interventions in computer aided surgery

PubMed Central

Zhang, Hui; Banovac, Filip; Lin, Ralph; Glossop, Neil; Wood, Bradford J.; Lindisch, David; Levy, Elliot; Cleary, Kevin

2014-01-01

Electromagnetic tracking has great potential for assisting physicians in precision placement of instruments during minimally invasive interventions in the abdomen, since electromagnetic tracking is not limited by the line-of-sight restrictions of optical tracking. A new generation of electromagnetic tracking has recently become available, with sensors small enough to be included in the tips of instruments. To fully exploit the potential of this technology, our research group has been developing a computer aided, image-guided system that uses electromagnetic tracking for visualization of the internal anatomy during abdominal interventions. As registration is a critical component in developing an accurate image-guided system, we present three registration techniques: 1) enhanced paired-point registration (time-stamp match registration and dynamic registration); 2) orientation-based registration; and 3) needle shape-based registration. Respiration compensation is another important issue, particularly in the abdomen, where respiratory motion can make precise targeting difficult. To address this problem, we propose reference tracking and affine transformation methods. Finally, we present our prototype navigation system, which integrates the registration, segmentation, path-planning and navigation functions to provide real-time image guidance in the clinical environment. The methods presented here have been tested with a respiratory phantom specially designed by our group and in swine animal studies under approved protocols. Based on these tests, we conclude that our system can provide quick and accurate localization of tracked instruments in abdominal interventions, and that it offers a user friendly display for the physician. PMID:16829506

Combination of ray-tracing and the method of moments for electromagnetic radiation analysis using reduced meshes

NASA Astrophysics Data System (ADS)

Delgado, Carlos; Cátedra, Manuel Felipe

2018-05-01

This work presents a technique that allows a very noticeable relaxation of the computational requirements for full-wave electromagnetic simulations based on the Method of Moments. A ray-tracing analysis of the geometry is performed in order to extract the critical points with significant contributions. These points are then used to generate a reduced mesh, considering the regions of the geometry that surround each critical point and taking into account the electrical path followed from the source. The electromagnetic analysis of the reduced mesh produces very accurate results, requiring a fraction of the resources that the conventional analysis would utilize.

Calculation of electromagnetic fields induced on a geostationary satellite by an electrostatic discharge

NASA Astrophysics Data System (ADS)

Froger, E.; Marque, J. P.

The electromagnetic response of an orbiting satellite to an electrostatic discharge is compared to that of the same object subjected (in a susceptibility test) to an injection current. In the absence of actual data, the comparison was performed on the basis of two numerical simulations: one using the GEODE particle code for the orbiting case, and the other using the ALICE code for a representative injection configuration. It is found that the evolution of the electromagnetic fields is controlled in particular by the particle emission rhythm, giving rise to an ejection flux 'slit' whose rise time is about several tens of nanoseconds.

Spiral-like multi-beam emission via transformation electromagnetics

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

Tichit, Paul-Henri, E-mail: paul-henri.tichit@u-psud.fr; Burokur, Shah Nawaz, E-mail: shah-nawaz.burokur@u-psud.fr; Lustrac, André de, E-mail: andre.de-lustrac@u-psud.fr

Transformation electromagnetics offers an unconventional approach for the design of novel radiating devices. Here, we propose an electromagnetic metamaterial able to split an isotropic radiation into multiple directive beams. By applying transformations that modify distance and angles, we show how the multiple directive beams can be steered at will. We describe transformation of the metric space and the calculation of the material parameters. Different transformations are proposed for a possible physical realization through the use of engineered artificial metamaterials. Full wave simulations are performed to validate the proposed approach. The idea paves the way to interesting applications in various domainsmore » in microwave and optical regimes.« less

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.

Finite element analysis of electromagnetic propagation in an absorbing wave guide

NASA Technical Reports Server (NTRS)

Baumeister, Kenneth J.

1986-01-01

Wave guides play a significant role in microwave space communication systems. The attenuation per unit length of the guide depends on its construction and design frequency range. A finite element Galerkin formulation has been developed to study TM electromagnetic propagation in complex two-dimensional absorbing wave guides. The analysis models the electromagnetic absorptive characteristics of a general wave guide which could be used to determine wall losses or simulate resistive terminations fitted into the ends of a guide. It is believed that the general conclusions drawn by using this simpler two-dimensional geometry will be fundamentally the same for other geometries.

Further evaluation of the constrained least squares electromagnetic compensation method

NASA Technical Reports Server (NTRS)

Smith, William T.

1991-01-01

Technologies exist for construction of antennas with adaptive surfaces that can compensate for many of the larger distortions caused by thermal and gravitational forces. However, as the frequency and size of reflectors increase, the subtle surface errors become significant and degrade the overall electromagnetic performance. Electromagnetic (EM) compensation through an adaptive feed array offers means for mitigation of surface distortion effects. Implementation of EM compensation is investigated with the measured surface errors of the NASA 15 meter hoop/column reflector antenna. Computer simulations are presented for: (1) a hybrid EM compensation technique, and (2) evaluating the performance of a given EM compensation method when implemented with discretized weights.

Reproducing continuous radio blackout using glow discharge plasma

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

Xie, Kai; Li, Xiaoping; Liu, Donglin

2013-10-15

A novel plasma generator is described that offers large-scale, continuous, non-magnetized plasma with a 30-cm-diameter hollow structure, which provides a path for an electromagnetic wave. The plasma is excited by a low-pressure glow discharge, with varying electron densities ranging from 10{sup 9} to 2.5 × 10{sup 11} cm{sup −3}. An electromagnetic wave propagation experiment reproduced a continuous radio blackout in UHF-, L-, and S-bands. The results are consistent with theoretical expectations. The proposed method is suitable in simulating a plasma sheath, and in researching communications, navigation, electromagnetic mitigations, and antenna compensation in plasma sheaths.

High-order FDTD methods for transverse electromagnetic systems in dispersive inhomogeneous media.

PubMed

Zhao, Shan

2011-08-15

This Letter introduces a novel finite-difference time-domain (FDTD) formulation for solving transverse electromagnetic systems in dispersive media. Based on the auxiliary differential equation approach, the Debye dispersion model is coupled with Maxwell's equations to derive a supplementary ordinary differential equation for describing the regularity changes in electromagnetic fields at the dispersive interface. The resulting time-dependent jump conditions are rigorously enforced in the FDTD discretization by means of the matched interface and boundary scheme. High-order convergences are numerically achieved for the first time in the literature in the FDTD simulations of dispersive inhomogeneous media. © 2011 Optical Society of America

Time-dependent phase shift of a retrieved pulse in off-resonant electromagnetically-induced-transparency-based light storage

NASA Astrophysics Data System (ADS)

Maynard, M.-A.; Bouchez, R.; Lugani, J.; Bretenaker, F.; Goldfarb, F.; Brion, E.

2015-11-01

We report measurements of the time-dependent phases of the leak and retrieved pulses obtained in electromagnetically-induced-transparency storage experiments with metastable helium vapor at room temperature. In particular, we investigate the influence of the optical detuning at two-photon resonance and provide numerical simulations of the full dynamical Maxwell-Bloch equations, which allow us to account for the experimental results.

Simulation Analysis of a Strip Dipole Excited Electromagnetic Band-Gap (EBG) Structure

DTIC Science & Technology

2015-07-01

unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT The design of an Electromagnetic Band-Gap (EBG) for a particular antenna application is...summarized. Discussion is provided on interpretation of the EBG reflection coefficient phase for antenna applications and on the range of the EBG bandwidth...It is determined for antenna applications that the reflection phase and current design methods may be misleading. Instead, it is opinioned and shown

Regulation of Electromagnetic Radiation: A Confusing Course through Modulating E and H Waves.

DTIC Science & Technology

1982-02-15

29 Biological Effects of RFR: Clinical Findings ......... 30 Cataract ........... . o . o ....... o 30 Psychological Effects...Claims Act alleges injuries to a contractor employee conducting tests of potential effects of electromagnetic pulse radiation on a Minuteman missile site...absorption is the position of the receiving object (e.g. human being, animal or simulated model test subject) relative to the E, H or K planes (K is a

Magnetic Excitations and Geometric Confinement; Theory and simulations

NASA Astrophysics Data System (ADS)

Wysin, Gary Matthew

2015-12-01

In this book, author Gary Wysin provides an overview of model systems and their behaviour and effects, and is intended for advanced students and researchers in physics, chemistry and engineering interested in confined magnetics. It is also suitable as an auxiliary text in a class on magnetism or solid state physics. Previous physics knowledge is expected, along with some basic knowledge of classical electromagnetism and electromagnetic waves for the latter chapters.

TORO II: A finite element computer program for nonlinear quasi-static problems in electromagnetics: Part 2, User`s manual

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

Gartling, D.K.

User instructions are given for the finite element, electromagnetics program, TORO II. The theoretical background and numerical methods used in the program are documented in SAND95-2472. The present document also describes a number of example problems that have been analyzed with the code and provides sample input files for typical simulations. 20 refs., 34 figs., 3 tabs.

GEANT4 Simulation of Neutron Detector for DAMPE

NASA Astrophysics Data System (ADS)

He, M.; Ma, T.; Chang, J.; Zhang, Y.; Huang, Y. Y.; Zang, J. J.; Wu, J.; Dong, T. K.

2016-01-01

During recent tens of years dark matter has gradually become a hot topic in astronomical research field, and related theory researches and experiment projects change with each passing day. The Dark Matter Particle Explorer (DAMPE) of our country is proposed under this background. As the probing object involves high energy electrons, appropriate methods must be taken to distinguish them from protons in order to reduce the event probability of other charged particles (e.g. a proton) being mistaken as electrons. The experiments show that, the hadronic shower of high energy proton in BGO electromagnetic calorimeter, which is usually accompanied by the emitting of large number of secondary neutrons, is significantly different from the electromagnetic shower of high energy electron. Through the detection of secondary neutron signal emitting from the bottom of BGO electromagnetic calorimeter and the shower shape of incident particles in BGO electromagnetic calorimeter, we can effectively distinguish whether the incident particles are high energy protons or electrons. This paper introduces the structure and detecting principle of DAMPE neutron detector. We use Monte-Carlo method with GEANT4 software to simulate the signal emitting from protons and electrons at characteristic energy in the neutron detector, and finally summarize the neutron detector's ability to distinguish protons and electrons under different electron acception efficiencies.

FD_BH: a program for simulating electromagnetic waves from a borehole antenna

USGS Publications Warehouse

Ellefsen, Karl J.

2002-01-01

Program FD_BH is used to simulate the electromagnetic waves generated by an antenna in a borehole. The model representing the antenna may include metallic parts, a coaxial cable as a feed to the driving point, and resistive loading. The program is written in the C programming language, and the program has been tested on both the Windows and the UNIX operating systems. This Open-File Report describes • The contents and organization of the Zip file (section 2). • The program files, the installation of the program, the input files, and the execution of the program (section 3). • Address to which suggestions for improving the program may be sent (section 4).

Liquid Metal Pump Technologies for Nuclear Surface Power

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.

2007-01-01

Multiple liquid metal pump options are reviewed for the purpose of determining the technologies that are best suited for inclusion in a nuclear reactor thermal simulator intended to rest prototypical space nuclear surface power system components. Conduction, induction and thermoelectric electromagnetic pumps are evaluated based on their performance characteristics and the technical issues associated with incorporation into a reactor system. A thermoelectric electromagnetic pump is selected as the best option for use in NASA-MSFC's Fission Surface Power-Primary Test Circuit reactor simulator based on its relative simplicity, low power supply mass penalty, flight heritage, and the promise of increased pump efficiency over those earlier pump designs through the use of skutterudite thermoelectric elements.

The Hydrogen Epoch of Reionization Array Dish. II. Characterization of Spectral Structure with Electromagnetic Simulations and Its Science Implications.

NASA Astrophysics Data System (ADS)

Ewall-Wice, Aaron; Bradley, Richard; Deboer, David; Hewitt, Jacqueline; Parsons, Aaron; Aguirre, James; Ali, Zaki S.; Bowman, Judd; Cheng, Carina; Neben, Abraham R.; Patra, Nipanjana; Thyagarajan, Nithyanandan; Venter, Mariet; de Lera Acedo, Eloy; Dillon, Joshua S.; Dickenson, Roger; Doolittle, Phillip; Egan, Dennis; Hedrick, Mike; Klima, Patricia; Kohn, Saul; Schaffner, Patrick; Shelton, John; Saliwanchik, Benjamin; Taylor, H. A.; Taylor, Rusty; Tegmark, Max; Wirt, Butch

2016-11-01

We use time-domain electromagnetic simulations to determine the spectral characteristics of the Hydrogen Epoch of Reionization Arrays (HERA) antenna. These simulations are part of a multi-faceted campaign to determine the effectiveness of the dish’s design for obtaining a detection of redshifted 21 cm emission from the epoch of reionization. Our simulations show the existence of reflections between HERA’s suspended feed and its parabolic dish reflector that fall below -40 dB at 150 ns and, for reasonable impedance matches, have a negligible impact on HERA’s ability to constrain EoR parameters. It follows that despite the reflections they introduce, dishes are effective for increasing the sensitivity of EoR experiments at a relatively low cost. We find that electromagnetic resonances in the HERA feed’s cylindrical skirt, which is intended to reduce cross coupling and beam ellipticity, introduces significant power at large delays (-40 dB at 200 ns), which can lead to some loss of measurable Fourier modes and a modest reduction in sensitivity. Even in the presence of this structure, we find that the spectral response of the antenna is sufficiently smooth for delay filtering to contain foreground emission at line-of-sight wave numbers below k ∥ ≲ 0.2 h Mpc-1, in the region where the current PAPER experiment operates. Incorporating these results into a Fisher Matrix analysis, we find that the spectral structure observed in our simulations has only a small effect on the tight constraints HERA can achieve on parameters associated with the astrophysics of reionization.

Micromechanical Prediction of the Effective Behavior of Fully Coupled Electro-Magneto-Thermo-Elastic Multiphase Composites

NASA Technical Reports Server (NTRS)

Aboudi, Jacob

2000-01-01

The micromechanical generalized method of cells model is employed for the prediction of the effective moduli of electro-magneto-thermo-elastic composites. These include the effective elastic, piezoelectric, piezomagnetic, dielectric, magnetic permeability, electromagnetic coupling moduli, as well as the effective thermal expansion coefficients and the associated pyroelectric and pyromagnetic constants. Results are given for fibrous and periodically bilaminated composites.

Covariant relativistic hydrodynamics of multispecies plasma and generalized Ohm's law

NASA Astrophysics Data System (ADS)

Gedalin, Michael

1996-04-01

Fully covariant hydrodynamical equations for a multispecies relativistic plasma in an external electromagnetic field are derived. The derived multifluid description takes into account binary Coulomb collisions, annihilation, and interaction with the photon background in terms of the invariant collision cross sections. A generalized Ohm's law is derived in a manifestly covariant form. Particular attention is devoted to the relativistic electron-positron plasma.

Simulation of π 0-γ separation study for proposed CMS forward electromagnetic calorimeter

DOE PAGES

Roy, Ashim; Jain, Shilpi; Banerjee, Sunanda; ...

2016-11-11

The Forward Electromagnetic Calorimeter of the CMS detector is going to be upgraded in the high luminosity running as the energy of the present Electromagnetic Calorimeter (PbWO4) will degrade in the high luminosity (luminosity 10 34 cm -2 s -1) running due to extensive radiation (hadron flux 10 13 neutrons cm, -2). Shashlik Electromagnetic Calorimeter which consists of alternate layers of 1.5 mm LYSO(Ce) crystal plates and 2.5 mm Tungsten absorbers, was a proposal for high luminosity running. One of the performance points for any electromagnetic calorimeter is the ability to separate π 0 s from true photons, since finalmore » states with photons are a clean and one of the most important final states in proton-proton collisions at the LHC. As a result, the objective of this project is to study the possibility of π 0 and γ separation in the Shashlik detector using Multivariate Analysis (MVA) technique.« less

Simulation of π 0-γ separation study for proposed CMS forward electromagnetic calorimeter

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

Roy, Ashim; Jain, Shilpi; Banerjee, Sunanda

The Forward Electromagnetic Calorimeter of the CMS detector is going to be upgraded in the high luminosity running as the energy of the present Electromagnetic Calorimeter (PbWO4) will degrade in the high luminosity (luminosity 10 34 cm -2 s -1) running due to extensive radiation (hadron flux 10 13 neutrons cm, -2). Shashlik Electromagnetic Calorimeter which consists of alternate layers of 1.5 mm LYSO(Ce) crystal plates and 2.5 mm Tungsten absorbers, was a proposal for high luminosity running. One of the performance points for any electromagnetic calorimeter is the ability to separate π 0 s from true photons, since finalmore » states with photons are a clean and one of the most important final states in proton-proton collisions at the LHC. As a result, the objective of this project is to study the possibility of π 0 and γ separation in the Shashlik detector using Multivariate Analysis (MVA) technique.« less

Test of Hadronic Interaction Models with the KASCADE Hadron Calorimeter

NASA Astrophysics Data System (ADS)

Milke, J.; KASCADE Collaboration

The interpretation of extensive air shower (EAS) measurements often requires the comparison with EAS simulations based on high-energy hadronic interaction models. These interaction models have to extrapolate into kinematical regions and energy ranges beyond the limit of present accelerators. Therefore, it is necessary to test whether these models are able to describe the EAS development in a consistent way. By measuring simultaneously the hadronic, electromagnetic, and muonic part of an EAS the experiment KASCADE offers best facilities for checking the models. For the EAS simulations the program CORSIKA with several hadronic event generators implemented is used. Different hadronic observables, e.g. hadron number, energy spectrum, lateral distribution, are investigated, as well as their correlations with the electromagnetic and muonic shower size. By comparing measurements and simulations the consistency of the description of the EAS development is checked. First results with the new interaction model NEXUS and the version II.5 of the model DPMJET, recently included in CORSIKA, are presented and compared with QGSJET simulations.

Electromagnetic gyrokinetic simulation in GTS

NASA Astrophysics Data System (ADS)

Ma, Chenhao; Wang, Weixing; Startsev, Edward; Lee, W. W.; Ethier, Stephane

2017-10-01

We report the recent development in the electromagnetic simulations for general toroidal geometry based on the particle-in-cell gyrokinetic code GTS. Because of the cancellation problem, the EM gyrokinetic simulation has numerical difficulties in the MHD limit where k⊥ρi -> 0 and/or β >me /mi . Recently several approaches has been developed to circumvent this problem: (1) p∥ formulation with analytical skin term iteratively approximated by simulation particles (Yang Chen), (2) A modified p∥ formulation with ∫ dtE∥ used in place of A∥ (Mishichenko); (3) A conservative theme where the electron density perturbation for the Poisson equation is calculated from an electron continuity equation (Bao) ; (4) double-split-weight scheme with two weights, one for Poisson equation and one for time derivative of Ampere's law, each with different splits designed to remove large terms from Vlasov equation (Startsev). These algorithms are being implemented into GTS framework for general toroidal geometry. The performance of these different algorithms will be compared for various EM modes.

Self-Consistent Model of Magnetospheric Electric Field, Ring Current, Plasmasphere, and Electromagnetic Ion Cyclotron Waves: Initial Results

NASA Technical Reports Server (NTRS)

Gamayunov, K. V.; Khazanov, G. V.; Liemohn, M. W.; Fok, M.-C.; Ridley, A. J.

2009-01-01

Further development of our self-consistent model of interacting ring current (RC) ions and electromagnetic ion cyclotron (EMIC) waves is presented. This model incorporates large scale magnetosphere-ionosphere coupling and treats self-consistently not only EMIC waves and RC ions, but also the magnetospheric electric field, RC, and plasmasphere. Initial simulations indicate that the region beyond geostationary orbit should be included in the simulation of the magnetosphere-ionosphere coupling. Additionally, a self-consistent description, based on first principles, of the ionospheric conductance is required. These initial simulations further show that in order to model the EMIC wave distribution and wave spectral properties accurately, the plasmasphere should also be simulated self-consistently, since its fine structure requires as much care as that of the RC. Finally, an effect of the finite time needed to reestablish a new potential pattern throughout the ionosphere and to communicate between the ionosphere and the equatorial magnetosphere cannot be ignored.

Carbon fiber manufacturing via plasma technology

DOEpatents

Paulauskas, Felix L.; Yarborough, Kenneth D.; Meek, Thomas T.

2002-01-01

The disclosed invention introduces a novel method of manufacturing carbon and/or graphite fibers that avoids the high costs associated with conventional carbonization processes. The method of the present invention avoids these costs by utilizing plasma technology in connection with electromagnetic radiation to produce carbon and/or graphite fibers from fully or partially stabilized carbon fiber precursors. In general, the stabilized or partially stabilized carbon fiber precursors are placed under slight tension, in an oxygen-free atmosphere, and carbonized using a plasma and electromagnetic radiation having a power input which is increased as the fibers become more carbonized and progress towards a final carbon or graphite product. In an additional step, the final carbon or graphite product may be surface treated with an oxygen-plasma treatment to enhance adhesion to matrix materials.

Black Hole Accretion Discs on a Moving Mesh

NASA Astrophysics Data System (ADS)

Ryan, Geoffrey

2017-01-01

We present multi-dimensional numerical simulations of black hole accretion disks relevant for the production of electromagnetic counterparts to gravitational wave sources. We perform these simulations with a new general relativistic version of the moving-mesh magnetohydrodynamics code DISCO which we will present. This open-source code, GR-DISCO uses an orbiting and shearing mesh which moves with the dominant flow velocity, greatly improving the numerical accuracy of the thermodynamic variables in supersonic flows while also reducing numerical viscosity and greatly increasing computational efficiency by allowing for a larger time step. We have used GR-DISCO to study black hole accretion discs subject to gravitational torques from a binary companion, relevant for both current and future supermassive binary black hole searches and also as a possible electromagnetic precursor mechanism for LIGO events. Binary torques in these discs excite spiral shockwaves which effectively transport angular momentum in the disc and propagate through the innermost stable orbit, leading to stress corresponding to an alpha-viscosity of 10-2. We also present three-dimensional GRMHD simulations of neutrino dominated accretion flows (NDAFs) occurring after a binary neutron star merger in order to elucidate the conditions for electromagnetic transient production accompanying these gravitational waves sources expected to be detected by LIGO in the near future.

Preliminary investigation of the microwave pyrolysis mechanism of sludge based on high frequency structure simulator simulation of the electromagnetic field distribution.

PubMed

Ma, Rui; Yuan, Nana; Sun, Shichang; Zhang, Peixin; Fang, Lin; Zhang, Xianghua; Zhao, Xuxin

2017-06-01

Under microwave irradiation, raw sludge was pyrolyzed mainly by evaporation of water, with a weight loss ratio of 84.8% and a maximum temperature not exceeding 200°C. High-temperature pyrolysis of SiC sludge could be realized, with a weight loss ratio of 93.4% and a final pyrolysis temperature of 1131.7°C. Variations between the electric field intensity distribution are the main reason for the differences of pyrolysis efficiencies. HFSS simulation showed that the electric field intensity of the raw sludge gradually decreased from 2.94×10 4 V/m to 0.88×10 4 V/m when pyrolysis ends, while that of SiC sludge decreased from 3.73×10 4 V/m at the beginning to 1.28×10 4 V/m, then increased to 4.03×10 4 V/m. The electromagnetic effect is the main factor (r≥0.91) influencing the temperature increase and weight loss of raw sludge. Both the electromagnetic effect and heat conduction effect influenced temperature rise and weight loss of SiC sludge, but the former's influence was comparatively larger. Copyright © 2017 Elsevier Ltd. All rights reserved.

Students' Development of Representational Competence Through the Sense of Touch

NASA Astrophysics Data System (ADS)

Magana, Alejandra J.; Balachandran, Sadhana

2017-06-01

Electromagnetism is an umbrella encapsulating several different concepts like electric current, electric fields and forces, and magnetic fields and forces, among other topics. However, a number of studies in the past have highlighted the poor conceptual understanding of electromagnetism concepts by students even after instruction. This study aims to identify novel forms of "hands-on" instruction that can result in representational competence and conceptual gain. Specifically, this study aimed to identify if the use of visuohaptic simulations can have an effect on student representations of electromagnetic-related concepts. The guiding questions is How do visuohaptic simulations influence undergraduate students' representations of electric forces? Participants included nine undergraduate students from science, technology, or engineering backgrounds who participated in a think-aloud procedure while interacting with a visuohaptic simulation. The think-aloud procedure was divided in three stages, a prediction stage, a minimally visual haptic stage, and a visually enhanced haptic stage. The results of this study suggest that students' accurately characterized and represented the forces felt around a particle, line, and ring charges either in the prediction stage, a minimally visual haptic stage or the visually enhanced haptic stage. Also, some students accurately depicted the three-dimensional nature of the field for each configuration in the two stages that included a tactile mode, where the point charge was the most challenging one.

Constructing Repairable Meta-Structures of Ultra-Broad-Band Electromagnetic Absorption from Three-Dimensional Printed Patterned Shells.

PubMed

Song, Wei-Li; Zhou, Zhili; Wang, Li-Chen; Cheng, Xiao-Dong; Chen, Mingji; He, Rujie; Chen, Haosen; Yang, Yazheng; Fang, Daining

2017-12-13

Ultra-broad-band electromagnetic absorption materials and structures are increasingly attractive for their critical role in competing with the advanced broad-band electromagnetic detection systems. Mechanically soft and weak wax-based materials composites are known to be insufficient to serve in practical electromagnetic absorption applications. To break through such barriers, here we developed an innovative strategy to enable the wax-based composites to be robust and repairable meta-structures by employing a three-dimensional (3D) printed polymeric patterned shell. Because of the integrated merits from both the dielectric loss wax-based composites and mechanically robust 3D printed shells, the as-fabricated meta-structures enable bear mechanical collision and compression, coupled with ultra-broad-band absorption (7-40 and 75-110 GHz, reflection loss  smaller than -10 dB) approaching state-of-the-art electromagnetic absorption materials. With the assistance of experiment and simulation methods, the design advantages and mechanism of employing such 3D printed shells for substantially promoting the electromagnetic absorption performance have been demonstrated. Therefore, such universal strategy that could be widely extended to other categories of wax-based composites highlights a smart stage on which high-performance practical multifunction meta-structures with ultra-broad-band electromagnetic absorption could be envisaged.

Massively parallel first-principles simulation of electron dynamics in materials

DOE PAGES

Draeger, Erik W.; Andrade, Xavier; Gunnels, John A.; ...

2017-08-01

Here we present a highly scalable, parallel implementation of first-principles electron dynamics coupled with molecular dynamics (MD). By using optimized kernels, network topology aware communication, and by fully distributing all terms in the time-dependent Kohn–Sham equation, we demonstrate unprecedented time to solution for disordered aluminum systems of 2000 atoms (22,000 electrons) and 5400 atoms (59,400 electrons), with wall clock time as low as 7.5 s per MD time step. Despite a significant amount of non-local communication required in every iteration, we achieved excellent strong scaling and sustained performance on the Sequoia Blue Gene/Q supercomputer at LLNL. We obtained up tomore » 59% of the theoretical sustained peak performance on 16,384 nodes and performance of 8.75 Petaflop/s (43% of theoretical peak) on the full 98,304 node machine (1,572,864 cores). Lastly, scalable explicit electron dynamics allows for the study of phenomena beyond the reach of standard first-principles MD, in particular, materials subject to strong or rapid perturbations, such as pulsed electromagnetic radiation, particle irradiation, or strong electric currents.« less

Particle-flow reconstruction and global event description with the CMS detector

DOE PAGES

Sirunyan, A. M.; Tumasyan, A.; Adam, W.; ...

2017-10-06

The CMS apparatus was identified, a few years before the start of the LHC operation at CERN, to feature properties well suited to particle-flow (PF) reconstruction: a highly-segmented tracker, a fine-grained electromagnetic calorimeter, a hermetic hadron calorimeter, a strong magnetic field, and an excellent muon spectrometer. A fully-fledged PF reconstruction algorithm tuned to the CMS detector was therefore developed and has been consistently used in physics analyses for the first time at a hadron collider. For each collision, the comprehensive list of final-state particles identified and reconstructed by the algorithm provides a global event description that leads to unprecedented CMSmore » performance for jet and hadronic tau decay reconstruction, missing transverse momentum determination, and electron and muon identification. This approach also allows particles from pileup interactions to be identified and enables efficient pileup mitigation methods. In conclusion, the data collected by CMS at a centre-of-mass energy of 8 TeV show excellent agreement with the simulation and confirm the superior PF performance at least up to an average of 20 pileup interactions.« less

Evaluation of Transient Pin-Stress Requirements for Spacecraft Launching in Lightning Environments. Pain Free Analysis to Alleviate Those Pin Stress Headaches

NASA Technical Reports Server (NTRS)

Edwards, Paul; Terseck, Alex; Trout, Dawn

2016-01-01

Spacecraft are generally protected from direct lightning attachment by encapsulation within the payload fairing of a launch vehicle and the ground structures that exist at the launch site. Regardless of where lightning strikes, potentially damaging indirect effects prevail from the coupling of electromagnetic fields into a loop created by outer shield of the payload umbilical. The energy coupled into individual spacecraft circuits is dependent on the umbilical current drive, the cable transfer impedance and the source/ load circuitry, and the reference potential used. Lightning induced transient susceptibility of the spacecraft avionics needs to be fully understood in order to define realistic re-test criteria in the event of a lightning occurrence during the launch campaign. Use of standards such as RTCA/DO-160 & SAE 5412 has some applicability but do not represent the indirect environment adequately. This paper evaluates the launch pad environments, the measurement data available, and computer simulations to provide pain-free analysis to alleviate the transient pin-stress headaches for spacecraft launching in Lightning environments.

Investigating EMIC Wave Dynamics with RAM-SCB-E

NASA Astrophysics Data System (ADS)

Jordanova, V. K.; Fu, X.; Henderson, M. G.; Morley, S.; Welling, D. T.; Yu, Y.

2017-12-01

The distribution of ring current ions and electrons in the inner magnetosphere depends strongly on their transport in realistic electric (E) and magnetic (B) fields and concurrent energization or loss. To investigate the high variability of energetic particle (H+, He+, O+, and electron) fluxes during storms selected by the GEM Surface Charging Challenge, we use our kinetic ring current model (RAM) two-way coupled with a 3-D magnetic field code (SCB). This model was just extended to include electric field calculations, making it a unique, fully self-consistent, anisotropic ring current-atmosphere interactions model, RAM-SCB-E. Recently we investigated electromagnetic ion cyclotron (EMIC) instability in a local plasma using both linear theory and nonlinear hybrid simulations and derived a scaling formula that relates the saturation EMIC wave amplitude to initial plasma conditions. Global dynamic EMIC wave maps obtained with our RAM-SCB-E model using this scaling will be presented and compared with statistical models. These plasma waves can affect significantly both ion and electron precipitation into the atmosphere and the subsequent patterns of ionospheric conductance, as well as the global ring current dynamics.

Time-Dependent Traveling Wave Tube Model for Intersymbol Interference Investigations

NASA Technical Reports Server (NTRS)

Kory, Carol L.; Andro, Monty; Downey, Alan (Technical Monitor)

2001-01-01

For the first time, a computational model has been used to provide a direct description of the effects of the traveling wave tube (TWT) on modulated digital signals. The TWT model comprehensively takes into account the effects of frequency dependent AM/AM and AM/PM conversion, gain and phase ripple; drive-induced oscillations; harmonic generation; intermodulation products; and backward waves. Thus, signal integrity can be investigated in the presence of these sources of potential distortion as a function of the physical geometry of the high power amplifier and the operational digital signal. This method promises superior predictive fidelity compared to methods using TWT models based on swept-amplitude and/or swept-frequency data. The fully three-dimensional (3D), time-dependent, TWT interaction model using the electromagnetic code MAFIA is presented. This model is used to investigate assumptions made in TWT black-box models used in communication system level simulations. In addition, digital signal performance, including intersymbol interference (ISI), is compared using direct data input into the MAFIA model and using the system level analysis tool, SPW.

Intersymbol Interference Investigations Using a 3D Time-Dependent Traveling Wave Tube Model

NASA Technical Reports Server (NTRS)

Kory, Carol L.; Andro, Monty; Downey, Alan (Technical Monitor)

2001-01-01

For the first time, a physics based computational model has been used to provide a direct description of the effects of the TWT (Traveling Wave Tube) on modulated digital signals. The TWT model comprehensively takes into account the effects of frequency dependent AM/AM and AM/PM conversion; gain and phase ripple; drive-induced oscillations; harmonic generation; intermodulation products; and backward waves. Thus, signal integrity can be investigated in the presence of these sources of potential distortion as a function of the physical geometry of the high power amplifier and the operational digital signal. This method promises superior predictive fidelity compared to methods using TWT models based on swept amplitude and/or swept frequency data. The fully three-dimensional (3D), time-dependent, TWT interaction model using the electromagnetic code MAFIA is presented. This model is used to investigate assumptions made in TWT black box models used in communication system level simulations. In addition, digital signal performance, including intersymbol interference (ISI), is compared using direct data input into the MAFIA model and using the system level analysis tool, SPW (Signal Processing Worksystem).

Experimental validation of tunable features in laser-induced plasma resonators

NASA Astrophysics Data System (ADS)

Colón Quiñones, Roberto A.; Cappelli, Mark A.

2017-08-01

Measurements are presented which examine the use of gaseous plasma elements as highly-tunable resonators. The resonator considered here is a laser-induced plasma kernel generated by focusing the fundamental output from a Q-switched Nd:YAG laser through a lens and into a gas at constant pressure. The near-ellipsoidal plasma element interacts with incoming microwave radiation through excitation of low-order, electric-dipole resonances similar to those seen in metallic spheres. The tunability of these elements stems from the dispersive nature of plasmas arising from their variable electron density, electron momentum transfer collision frequency, and the concomitant e↵ect of these properties on the excited surface plasmon resonance. Experiments were carried out in the Ku band of the microwave spectrum to characterize the scattering properties of these resonators for di↵erent values of electron density. The experimental results are compared with results from theoretical approximations and finite element method electromagnetic simulations. The described tunable resonators have the potential to be used as the building blocks in a new class of all-plasma metamaterials with fully three-dimensional structural flexibility.

Massively parallel first-principles simulation of electron dynamics in materials

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

Draeger, Erik W.; Andrade, Xavier; Gunnels, John A.

Here we present a highly scalable, parallel implementation of first-principles electron dynamics coupled with molecular dynamics (MD). By using optimized kernels, network topology aware communication, and by fully distributing all terms in the time-dependent Kohn–Sham equation, we demonstrate unprecedented time to solution for disordered aluminum systems of 2000 atoms (22,000 electrons) and 5400 atoms (59,400 electrons), with wall clock time as low as 7.5 s per MD time step. Despite a significant amount of non-local communication required in every iteration, we achieved excellent strong scaling and sustained performance on the Sequoia Blue Gene/Q supercomputer at LLNL. We obtained up tomore » 59% of the theoretical sustained peak performance on 16,384 nodes and performance of 8.75 Petaflop/s (43% of theoretical peak) on the full 98,304 node machine (1,572,864 cores). Lastly, scalable explicit electron dynamics allows for the study of phenomena beyond the reach of standard first-principles MD, in particular, materials subject to strong or rapid perturbations, such as pulsed electromagnetic radiation, particle irradiation, or strong electric currents.« less

Particle-flow reconstruction and global event description with the CMS detector

NASA Astrophysics Data System (ADS)

Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; König, A.; Krätschmer, I.; Liko, D.; Matsushita, T.; Mikulec, I.; Rabady, D.; Rad, N.; Rahbaran, B.; Rohringer, H.; Schieck, J.; Strauss, J.; Waltenberger, W.; Wulz, C.-E.; Dvornikov, O.; Makarenko, V.; Mossolov, V.; Suarez Gonzalez, J.; Zykunov, V.; Shumeiko, N.; Alderweireldt, S.; De Wolf, E. A.; Janssen, X.; Lauwers, J.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; Daci, N.; De Bruyn, I.; Deroover, K.; Lowette, S.; Moortgat, S.; Moreels, L.; Olbrechts, A.; Python, Q.; Skovpen, K.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Parijs, I.; Brun, H.; Clerbaux, B.; De Lentdecker, G.; Delannoy, H.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, T.; Léonard, A.; Luetic, J.; Maerschalk, T.; Marinov, A.; Randle-conde, A.; Seva, T.; Vander Velde, C.; Vanlaer, P.; Vannerom, D.; Yonamine, R.; Zenoni, F.; Zhang, F.; Cornelis, T.; Dobur, D.; Fagot, A.; Gul, M.; Khvastunov, I.; Poyraz, D.; Salva, S.; Schöfbeck, R.; Tytgat, M.; Van Driessche, W.; Yazgan, E.; Zaganidis, N.; Bakhshiansohi, H.; Bondu, O.; Brochet, S.; Bruno, G.; Caudron, A.; De Visscher, S.; Delaere, C.; Delcourt, M.; Francois, B.; Giammanco, A.; Jafari, A.; Komm, M.; Krintiras, G.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Musich, M.; Piotrzkowski, K.; Quertenmont, L.; Selvaggi, M.; Vidal Marono, M.; Wertz, S.; Beliy, N.; Aldá Júnior, W. L.; Alves, F. L.; Alves, G. A.; Brito, L.; Hensel, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Belchior Batista Das Chagas, E.; Carvalho, W.; Chinellato, J.; Custódio, A.; Da Costa, E. M.; Da Silveira, G. G.; Damiao, D. De Jesus; De Oliveira Martins, C.; Fonseca De Souza, S.; Huertas Guativa, L. M.; Malbouisson, H.; Matos Figueiredo, D.; Mora Herrera, C.; Mundim, L.; Nogima, H.; Prado Da Silva, W. L.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Torres Da Silva De Araujo, F.; Vilela Pereira, A.; Ahuja, S.; Bernardes, C. A.; Dogra, S.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Moon, C. S.; Novaes, S. F.; Padula, Sandra S.; Romero Abad, D.; Ruiz Vargas, J. C.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Glushkov, I.; Litov, L.; Pavlov, B.; Petkov, P.; Fang, W.; Ahmad, M.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Chen, Y.; Cheng, T.; Jiang, C. H.; Leggat, D.; Liu, Z.; Romeo, F.; Ruan, M.; Shaheen, S. M.; Spiezia, A.; Tao, J.; Wang, C.; Wang, Z.; Zhang, H.; Zhao, J.; Ban, Y.; Chen, G.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Xu, Z.; Avila, C.; Cabrera, A.; Chaparro Sierra, L. F.; Florez, C.; Gomez, J. P.; González Hernández, C. F.; Ruiz Alvarez, J. D.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Puljak, I.; Ribeiro Cipriano, P. M.; Sculac, T.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Ferencek, D.; Kadija, K.; Mesic, B.; Susa, T.; Ather, M. W.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Rykaczewski, H.; Finger, M.; Finger, M., Jr.; Carrera Jarrin, E.; El-khateeb, E.; Elgammal, S.; Mohamed, A.; Kadastik, M.; Perrini, L.; Raidal, M.; Tiko, A.; Veelken, C.; Eerola, P.; Pekkanen, J.; Voutilainen, M.; Härkönen, J.; Järvinen, T.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Tuominiemi, J.; Tuovinen, E.; Wendland, L.; Talvitie, J.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Favaro, C.; Ferri, F.; Ganjour, S.; Ghosh, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Kucher, I.; Locci, E.; Machet, M.; Malcles, J.; Rander, J.; Rosowsky, A.; Titov, M.; Abdulsalam, A.; Antropov, I.; Baffioni, S.; Beaudette, F.; Busson, P.; Cadamuro, L.; Chapon, E.; Charlot, C.; Davignon, O.; Granier de Cassagnac, R.; Jo, M.; Lisniak, S.; Miné, P.; Nguyen, M.; Ochando, C.; Ortona, G.; Paganini, P.; Pigard, P.; Regnard, S.; Salerno, R.; Sirois, Y.; Stahl Leiton, A. G.; Strebler, T.; Yilmaz, Y.; Zabi, A.; Zghiche, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Brom, J.-M.; Buttignol, M.; Chabert, E. C.; Chanon, N.; Collard, C.; Conte, E.; Coubez, X.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Le Bihan, A.-C.; Van Hove, P.; Gadrat, S.; Beauceron, S.; Bernet, C.; Boudoul, G.; Carrillo Montoya, C. A.; Chierici, R.; Contardo, D.; Courbon, B.; Depasse, P.; El Mamouni, H.; Fay, J.; Gascon, S.; Gouzevitch, M.; Grenier, G.; Ille, B.; Lagarde, F.; Laktineh, I. B.; Lethuillier, M.; Mirabito, L.; Pequegnot, A. L.; Perries, S.; Popov, A.; Sordini, V.; Vander Donckt, M.; Verdier, P.; Viret, S.; Toriashvili, T.; Tsamalaidze, Z.; Autermann, C.; Beranek, S.; Feld, L.; Kiesel, M. K.; Klein, K.; Lipinski, M.; Preuten, M.; Schomakers, C.; Schulz, J.; Verlage, T.; Albert, A.; Brodski, M.; Dietz-Laursonn, E.; Duchardt, D.; Endres, M.; Erdmann, M.; Erdweg, S.; Esch, T.; Fischer, R.; Güth, A.; Hamer, M.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Knutzen, S.; Merschmeyer, M.; Meyer, A.; Millet, P.; Mukherjee, S.; Olschewski, M.; Padeken, K.; Pook, T.; Radziej, M.; Reithler, H.; Rieger, M.; Scheuch, F.; Sonnenschein, L.; Teyssier, D.; Thüer, S.; Cherepanov, V.; Flügge, G.; Kargoll, B.; Kress, T.; Künsken, A.; Lingemann, J.; Müller, T.; Nehrkorn, A.; Nowack, A.; Pistone, C.; Pooth, O.; Stahl, A.; Aldaya Martin, M.; Arndt, T.; Asawatangtrakuldee, C.; Beernaert, K.; Behnke, O.; Behrens, U.; Anuar, A. A. Bin; Borras, K.; Campbell, A.; Connor, P.; Contreras-Campana, C.; Costanza, F.; Diez Pardos, C.; Dolinska, G.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Eren, E.; Gallo, E.; Garay Garcia, J.; Geiser, A.; Gizhko, A.; Grados Luyando, J. 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R.; Williams, T.; Baber, M.; Bainbridge, R.; Buchmuller, O.; Bundock, A.; Casasso, S.; Citron, M.; Colling, D.; Corpe, L.; Dauncey, P.; Davies, G.; De Wit, A.; Della Negra, M.; Di Maria, R.; Dunne, P.; Elwood, A.; Futyan, D.; Haddad, Y.; Hall, G.; Iles, G.; James, T.; Lane, R.; Laner, C.; Lyons, L.; Magnan, A.-M.; Malik, S.; Mastrolorenzo, L.; Nash, J.; Nikitenko, A.; Pela, J.; Penning, B.; Pesaresi, M.; Raymond, D. M.; Richards, A.; Rose, A.; Scott, E.; Seez, C.; Summers, S.; Tapper, A.; Uchida, K.; Vazquez Acosta, M.; Virdee, T.; Wright, J.; Zenz, S. C.; Cole, J. E.; Hobson, P. R.; Khan, A.; Kyberd, P.; Reid, I. D.; Symonds, P.; Teodorescu, L.; Turner, M.; Borzou, A.; Call, K.; Dittmann, J.; Hatakeyama, K.; Liu, H.; Pastika, N.; Bartek, R.; Dominguez, A.; Buccilli, A.; Cooper, S. I.; Henderson, C.; Rumerio, P.; West, C.; Arcaro, D.; Avetisyan, A.; Bose, T.; Gastler, D.; Rankin, D.; Richardson, C.; Rohlf, J.; Sulak, L.; Zou, D.; Benelli, G.; Cutts, D.; Garabedian, A.; Hakala, J.; Heintz, U.; Hogan, J. M.; Jesus, O.; Kwok, K. H. M.; Laird, E.; Landsberg, G.; Mao, Z.; Narain, M.; Piperov, S.; Sagir, S.; Spencer, E.; Syarif, R.; Breedon, R.; Burns, D.; Calderon De La Barca Sanchez, M.; Chauhan, S.; Chertok, M.; Conway, J.; Conway, R.; Cox, P. T.; Erbacher, R.; Flores, C.; Funk, G.; Gardner, M.; Ko, W.; Lander, R.; Mclean, C.; Mulhearn, M.; Pellett, D.; Pilot, J.; Shalhout, S.; Shi, M.; Smith, J.; Squires, M.; Stolp, D.; Tos, K.; Tripathi, M.; Bachtis, M.; Bravo, C.; Cousins, R.; Dasgupta, A.; Florent, A.; Hauser, J.; Ignatenko, M.; Mccoll, N.; Saltzberg, D.; Schnaible, C.; Valuev, V.; Weber, M.; Bouvier, E.; Burt, K.; Clare, R.; Ellison, J.; Gary, J. W.; Ghiasi Shirazi, S. M. A.; Hanson, G.; Heilman, J.; Jandir, P.; Kennedy, E.; Lacroix, F.; Long, O. R.; Olmedo Negrete, M.; Paneva, M. I.; Shrinivas, A.; Si, W.; Wei, H.; Wimpenny, S.; Yates, B. R.; Branson, J. G.; Cerati, G. B.; Cittolin, S.; Derdzinski, M.; Gerosa, R.; Holzner, A.; Klein, D.; Krutelyov, V.; Letts, J.; Macneill, I.; Olivito, D.; Padhi, S.; Pieri, M.; Sani, M.; Sharma, V.; Simon, S.; Tadel, M.; Vartak, A.; Wasserbaech, S.; Welke, C.; Wood, J.; Würthwein, F.; Yagil, A.; Zevi Della Porta, G.; Amin, N.; Bhandari, R.; Bradmiller-Feld, J.; Campagnari, C.; Dishaw, A.; Dutta, V.; Sevilla, M. Franco; George, C.; Golf, F.; Gouskos, L.; Gran, J.; Heller, R.; Incandela, J.; Mullin, S. D.; Ovcharova, A.; Qu, H.; Richman, J.; Stuart, D.; Suarez, I.; Yoo, J.; Anderson, D.; Bendavid, J.; Bornheim, A.; Bunn, J.; Duarte, J.; Lawhorn, J. M.; Mott, A.; Newman, H. B.; Pena, C.; Spiropulu, M.; Vlimant, J. R.; Xie, S.; Zhu, R. Y.; Andrews, M. B.; Ferguson, T.; Paulini, M.; Russ, J.; Sun, M.; Vogel, H.; Vorobiev, I.; Weinberg, M.; Cumalat, J. P.; Ford, W. T.; Jensen, F.; Johnson, A.; Krohn, M.; Leontsinis, S.; Mulholland, T.; Stenson, K.; Wagner, S. R.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; Mcdermott, K.; Mirman, N.; Patterson, J. R.; Rinkevicius, A.; Ryd, A.; Skinnari, L.; Soffi, L.; Tan, S. M.; Tao, Z.; Thom, J.; Tucker, J.; Wittich, P.; Zientek, M.; Winn, D.; Abdullin, S.; Albrow, M.; Apollinari, G.; Apresyan, A.; Banerjee, S.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Bolla, G.; Burkett, K.; Butler, J. N.; Cheung, H. W. K.; Chlebana, F.; Cihangir, S.; Cremonesi, M.; Elvira, V. D.; Fisk, I.; Freeman, J.; Gottschalk, E.; Gray, L.; Green, D.; Grünendahl, S.; Gutsche, O.; Hare, D.; Harris, R. M.; Hasegawa, S.; Hirschauer, J.; Hu, Z.; Jayatilaka, B.; Jindariani, S.; Johnson, M.; Joshi, U.; Klima, B.; Kreis, B.; Lammel, S.; Linacre, J.; Lincoln, D.; Lipton, R.; Liu, M.; Liu, T.; Lopes De Sá, R.; Lykken, J.; Maeshima, K.; Magini, N.; Marraffino, J. M.; Maruyama, S.; Mason, D.; McBride, P.; Merkel, P.; Mrenna, S.; Nahn, S.; O'Dell, V.; Pedro, K.; Prokofyev, O.; Rakness, G.; Ristori, L.; Sexton-Kennedy, E.; Soha, A.; Spalding, W. J.; Spiegel, L.; Stoynev, S.; Strait, J.; Strobbe, N.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vernieri, C.; Verzocchi, M.; Vidal, R.; Wang, M.; Weber, H. A.; Whitbeck, A.; Wu, Y.; Acosta, D.; Avery, P.; Bortignon, P.; Bourilkov, D.; Brinkerhoff, A.; Carnes, A.; Carver, M.; Curry, D.; Das, S.; Field, R. D.; Furic, I. K.; Konigsberg, J.; Korytov, A.; Low, J. F.; Ma, P.; Matchev, K.; Mei, H.; Mitselmakher, G.; Rank, D.; Shchutska, L.; Sperka, D.; Thomas, L.; Wang, J.; Wang, S.; Yelton, J.; Linn, S.; Markowitz, P.; Martinez, G.; Rodriguez, J. L.; Ackert, A.; Adams, T.; Askew, A.; Bein, S.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Kolberg, T.; Perry, T.; Prosper, H.; Santra, A.; Yohay, R.; Baarmand, M. M.; Bhopatkar, V.; Colafranceschi, S.; Hohlmann, M.; Noonan, D.; Roy, T.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Berry, D.; Betts, R. R.; Cavanaugh, R.; Chen, X.; Evdokimov, O.; Gerber, C. E.; Hangal, D. A.; Hofman, D. J.; Jung, K.; Kamin, J.; Sandoval Gonzalez, I. D.; Trauger, H.; Varelas, N.; Wang, H.; Wu, Z.; Zakaria, M.; Zhang, J.; Bilki, B.; Clarida, W.; Dilsiz, K.; Durgut, S.; Gandrajula, R. P.; Haytmyradov, M.; Khristenko, V.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Snyder, C.; Tiras, E.; Wetzel, J.; Yi, K.; Blumenfeld, B.; Cocoros, A.; Eminizer, N.; Fehling, D.; Feng, L.; Gritsan, A. V.; Maksimovic, P.; Roskes, J.; Sarica, U.; Swartz, M.; Xiao, M.; You, C.; Al-bataineh, A.; Baringer, P.; Bean, A.; Boren, S.; Bowen, J.; Castle, J.; Forthomme, L.; Khalil, S.; Kropivnitskaya, A.; Majumder, D.; Mcbrayer, W.; Murray, M.; Sanders, S.; Stringer, R.; Tapia Takaki, J. D.; Wang, Q.; Ivanov, A.; Kaadze, K.; Maravin, Y.; Mohammadi, A.; Saini, L. K.; Skhirtladze, N.; Toda, S.; Rebassoo, F.; Wright, D.; Anelli, C.; Baden, A.; Baron, O.; Belloni, A.; Calvert, B.; Eno, S. C.; Ferraioli, C.; Gomez, J. A.; Hadley, N. J.; Jabeen, S.; Jeng, G. Y.; Kellogg, R. G.; Kunkle, J.; Mignerey, A. C.; Ricci-Tam, F.; Shin, Y. H.; Skuja, A.; Tonjes, M. B.; Tonwar, S. C.; Abercrombie, D.; Allen, B.; Apyan, A.; Azzolini, V.; Barbieri, R.; Baty, A.; Bi, R.; Bierwagen, K.; Brandt, S.; Busza, W.; Cali, I. A.; D'Alfonso, M.; Demiragli, Z.; Gomez Ceballos, G.; Goncharov, M.; Hsu, D.; Iiyama, Y.; Innocenti, G. M.; Klute, M.; Kovalskyi, D.; Krajczar, K.; Lai, Y. S.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; Maier, B.; Marini, A. C.; Mcginn, C.; Mironov, C.; Narayanan, S.; Niu, X.; Paus, C.; Roland, C.; Roland, G.; Salfeld-Nebgen, J.; Stephans, G. S. F.; Tatar, K.; Velicanu, D.; Wang, J.; Wang, T. W.; Wyslouch, B.; Benvenuti, A. C.; Chatterjee, R. M.; Evans, A.; Hansen, P.; Kalafut, S.; Kao, S. C.; Kubota, Y.; Lesko, Z.; Mans, J.; Nourbakhsh, S.; Ruckstuhl, N.; Rusack, R.; Tambe, N.; Turkewitz, J.; Acosta, J. G.; Oliveros, S.; Avdeeva, E.; Bloom, K.; Claes, D. R.; Fangmeier, C.; Gonzalez Suarez, R.; Kamalieddin, R.; Kravchenko, I.; Malta Rodrigues, A.; Monroy, J.; Siado, J. E.; Snow, G. R.; Stieger, B.; Alyari, M.; Dolen, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Kaisen, J.; Nguyen, D.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alverson, G.; Barberis, E.; Hortiangtham, A.; Massironi, A.; Morse, D. M.; Nash, D.; Orimoto, T.; Teixeira De Lima, R.; Trocino, D.; Wang, R.-J.; Wood, D.; Bhattacharya, S.; Charaf, O.; Hahn, K. A.; Mucia, N.; Odell, N.; Pollack, B.; Schmitt, M. H.; Sung, K.; Trovato, M.; Velasco, M.; Dev, N.; Hildreth, M.; Hurtado Anampa, K.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Marinelli, N.; Meng, F.; Mueller, C.; Musienko, Y.; Planer, M.; Reinsvold, A.; Ruchti, R.; Rupprecht, N.; Smith, G.; Taroni, S.; Wayne, M.; Wolf, M.; Woodard, A.; Alimena, J.; Antonelli, L.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Francis, B.; Hart, A.; Hill, C.; Ji, W.; Liu, B.; Luo, W.; Puigh, D.; Winer, B. L.; Wulsin, H. W.; Cooperstein, S.; Driga, O.; Elmer, P.; Hardenbrook, J.; Hebda, P.; Lange, D.; Luo, J.; Marlow, D.; Medvedeva, T.; Mei, K.; Ojalvo, I.; Olsen, J.; Palmer, C.; Piroué, P.; Stickland, D.; Svyatkovskiy, A.; Tully, C.; Malik, S.; Barker, A.; Barnes, V. E.; Folgueras, S.; Gutay, L.; Jha, M. K.; Jones, M.; Jung, A. W.; Khatiwada, A.; Miller, D. H.; Neumeister, N.; Schulte, J. F.; Shi, X.; Sun, J.; Wang, F.; Xie, W.; Parashar, N.; Stupak, J.; Adair, A.; Akgun, B.; Chen, Z.; Ecklund, K. M.; Geurts, F. J. M.; Guilbaud, M.; Li, W.; Michlin, B.; Northup, M.; Padley, B. P.; Roberts, J.; Rorie, J.; Tu, Z.; Zabel, J.; Betchart, B.; Bodek, A.; de Barbaro, P.; Demina, R.; Duh, Y. t.; Ferbel, T.; Galanti, M.; Garcia-Bellido, A.; Han, J.; Hindrichs, O.; Khukhunaishvili, A.; Lo, K. H.; Tan, P.; Verzetti, M.; Agapitos, A.; Chou, J. P.; Gershtein, Y.; Gómez Espinosa, T. A.; Halkiadakis, E.; Heindl, M.; Hughes, E.; Kaplan, S.; Kunnawalkam Elayavalli, R.; Kyriacou, S.; Lath, A.; Montalvo, R.; Nash, K.; Osherson, M.; Saka, H.; Salur, S.; Schnetzer, S.; Sheffield, D.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Delannoy, A. G.; Foerster, M.; Heideman, J.; Riley, G.; Rose, K.; Spanier, S.; Thapa, K.; Bouhali, O.; Celik, A.; Dalchenko, M.; De Mattia, M.; Delgado, A.; Dildick, S.; Eusebi, R.; Gilmore, J.; Huang, T.; Juska, E.; Kamon, T.; Mueller, R.; Pakhotin, Y.; Patel, R.; Perloff, A.; Perniè, L.; Rathjens, D.; Safonov, A.; Tatarinov, A.; Ulmer, K. A.; Akchurin, N.; Damgov, J.; De Guio, F.; Dragoiu, C.; Dudero, P. R.; Faulkner, J.; Gurpinar, E.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Libeiro, T.; Peltola, T.; Undleeb, S.; Volobouev, I.; Wang, Z.; Greene, S.; Gurrola, A.; Janjam, R.; Johns, W.; Maguire, C.; Melo, A.; Ni, H.; Sheldon, P.; Tuo, S.; Velkovska, J.; Xu, Q.; Arenton, M. W.; Barria, P.; Cox, B.; Hirosky, R.; Ledovskoy, A.; Li, H.; Neu, C.; Sinthuprasith, T.; Sun, X.; Wang, Y.; Wolfe, E.; Xia, F.; Clarke, C.; Harr, R.; Karchin, P. E.; Sturdy, J.; Zaleski, S.; Belknap, D. A.; Buchanan, J.; Caillol, C.; Dasu, S.; Dodd, L.; Duric, S.; Gomber, B.; Grothe, M.; Herndon, M.; Hervé, A.; Hussain, U.; Klabbers, P.; Lanaro, A.; Levine, A.; Long, K.; Loveless, R.; Pierro, G. A.; Polese, G.; Ruggles, T.; Savin, A.; Smith, N.; Smith, W. H.; Taylor, D.; Woods, N.

2017-10-01

The CMS apparatus was identified, a few years before the start of the LHC operation at CERN, to feature properties well suited to particle-flow (PF) reconstruction: a highly-segmented tracker, a fine-grained electromagnetic calorimeter, a hermetic hadron calorimeter, a strong magnetic field, and an excellent muon spectrometer. A fully-fledged PF reconstruction algorithm tuned to the CMS detector was therefore developed and has been consistently used in physics analyses for the first time at a hadron collider. For each collision, the comprehensive list of final-state particles identified and reconstructed by the algorithm provides a global event description that leads to unprecedented CMS performance for jet and hadronic τ decay reconstruction, missing transverse momentum determination, and electron and muon identification. This approach also allows particles from pileup interactions to be identified and enables efficient pileup mitigation methods. The data collected by CMS at a centre-of-mass energy of 8\\TeV show excellent agreement with the simulation and confirm the superior PF performance at least up to an average of 20 pileup interactions.

Particle-flow reconstruction and global event description with the CMS detector

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

Sirunyan, A.M.; et al.

2017-10-06

The CMS apparatus was identified, a few years before the start of the LHC operation at CERN, to feature properties well suited to particle-flow (PF) reconstruction: a highly-segmented tracker, a fine-grained electromagnetic calorimeter, a hermetic hadron calorimeter, a strong magnetic field, and an excellent muon spectrometer. A fully-fledged PF reconstruction algorithm tuned to the CMS detector was therefore developed and has been consistently used in physics analyses for the first time at a hadron collider. For each collision, the comprehensive list of final-state particles identified and reconstructed by the algorithm provides a global event description that leads to unprecedented CMSmore » performance for jet and hadronic tau decay reconstruction, missing transverse momentum determination, and electron and muon identification. This approach also allows particles from pileup interactions to be identified and enables efficient pileup mitigation methods. The data collected by CMS at a centre-of-mass energy of 8 TeV show excellent agreement with the simulation and confirm the superior PF performance at least up to an average of 20 pileup interactions.« less

Casimir forces on a bi-anisotropic absorbing magneto-dielectric slab between two parallel conducting plates

NASA Astrophysics Data System (ADS)

Amooshahi, Majid; Shoughi, Ali

2018-05-01

A fully canonical quantization of electromagnetic field in the presence of a bi-anisotropic absorbing magneto-dielectric slab is demonstrated. The electric and the magnetic polarization densities of the magneto-dielectric slab are defined in terms of the dynamical variables modeling the slab and the coupling tensors that couple the electromagnetic field to the slab. The four susceptibility tensors of the bi-anisotropic magneto-dielectric slab are expressed in terms of the coupling tensors that couple an electromagnetic field to the slab. It is shown that the four susceptibility tensors of the bi-anisotropic magneto-dielectric slab satisfy Kramers-Kronig relations. The Maxwell’s equations are exactly solved in the presence of the bi-anisotropic magneto-dielectric slab. The tangential and the normal components of the Casimir forces exerted on the bi-anisotropic magnet-dielectric slab exactly are calculated in the vacuum state and thermal state of the total system. It is shown that the tangential components of the Casimir forces vanish when the bi-anisotropic slab is converted to an isotropic slab.

Ionosphere research with a HF/MF cubesat radio instrument

NASA Astrophysics Data System (ADS)

Kallio, Esa; Aikio, Anita; Alho, Markku; Fontell, Mathias; Harri, Ari-Matti; Kauristie, Kirsti; Kestilä, Antti; Koskimaa, Petri; Mäkelä, Jakke; Mäkelä, Miika; Turunen, Esa; Vanhamäki, Heikki; Verronen, Pekka

2017-04-01

New technology provides new possibilities to study geospace and 3D ionosphere by using spacecraft and computer simulations. A type of nanosatellites, CubeSats, provide a cost effective possibility to provide in-situ measurements in the ionosphere. Moreover, combined CubeSat observations with ground-based observations gives a new view on auroras and associated electromagnetic phenomena. Especially joint and active CubeSat - ground based observation campaigns enable the possibility of studying the 3D structure of the ionosphere. Furthermore using several CubeSats to form satellite constellations enables much higher temporal resolution. At the same time, increasing computation capacity has made it possible to perform simulations where properties of the ionosphere, such as propagation of the electromagnetic waves in the medium frequency, MF (0.3-3 MHz) and high frequency, HF (3-30 MHz), ranges is based on a 3D ionospheric model and on first-principles modelling. Electromagnetic waves at those frequencies are strongly affected by ionospheric electrons and, consequently, those frequencies can be used for studying the plasma. On the other hand, even if the ionosphere originally enables long-range telecommunication at MF and HF frequencies, the frequent occurrence of spatiotemporal variations in the ionosphere disturbs communication channels, especially at high latitudes. Therefore, study of the MF and HF waves in the ionosphere has both a strong science and technology interests. We introduce recently developed simulation models as well as measuring principles and techniques to investigate the arctic ionosphere by a polar orbiting CubeSat whose novel AM radio instrument measures HF and MF waves. The cubesat, which contains also a white light aurora camera, is planned to be launched in late 2017 (http://www.suomi100satelliitti.fi/eng). The new models are (1) a 3D ray tracing model and (2) a 3D full kinetic electromagnetic simulation. We also introduce how combining of the cubesat measurements to ground based measurements provides new research possibilities to study 3D ionosphere.

Design and simulation of printed spiral coil used in wireless power transmission systems for implant medical devices.

PubMed

Wu, Wei; Fang, Qiang

2011-01-01

Printed Spiral Coil (PSC) is a coil antenna for near-field wireless power transmission to the next generation implant medical devices. PSC for implant medical device should be power efficient and low electromagnetic radiation to human tissues. We utilized a physical model of printed spiral coil and applied our algorithm to design PSC operating at 13.56 MHz. Numerical and electromagnetic simulation of power transfer efficiency of PSC in air medium is 77.5% and 71.1%, respectively. The simulation results show that the printed spiral coil which is optimized for air will keep 15.2% power transfer efficiency in human subcutaneous tissues. In addition, the Specific Absorption Ratio (SAR) for this coil antenna in subcutaneous at 13.56 MHz is below 1.6 W/Kg, which suggests this coil is implantable safe based on IEEE C95.1 safety guideline.

Equivalent circuit and characteristic simulation of a brushless electrically excited synchronous wind power generator

NASA Astrophysics Data System (ADS)

Wang, Hao; Zhang, Fengge; Guan, Tao; Yu, Siyang

2017-09-01

A brushless electrically excited synchronous generator (BEESG) with a hybrid rotor is a novel electrically excited synchronous generator. The BEESG proposed in this paper is composed of a conventional stator with two different sets of windings with different pole numbers, and a hybrid rotor with powerful coupling capacity. The pole number of the rotor is different from those of the stator windings. Thus, an analysis method different from that applied to conventional generators should be applied to the BEESG. In view of this problem, the equivalent circuit and electromagnetic torque expression of the BEESG are derived on the basis of electromagnetic relation of the proposed generator. The generator is simulated and tested experimentally using the established equivalent circuit model. The experimental and simulation data are then analyzed and compared. Results show the validity of the equivalent circuit model.

Global simulation of edge pedestal micro-instabilities

NASA Astrophysics Data System (ADS)

Wan, Weigang; Parker, Scott; Chen, Yang

2011-10-01

We study micro turbulence of the tokamak edge pedestal with global gyrokinetic particle simulations. The simulation code GEM is an electromagnetic δf code. Two sets of DIII-D experimental profiles, shot #131997 and shot #136051 are used. The dominant instabilities appear to be two kinds of modes both propagating in the electron diamagnetic direction, with comparable linear growth rates. The low n mode is at the Alfven frequency range and driven by density and ion temperature gradients. The high n mode is driven by electron temperature gradient and has a low real frequency. A β scan shows that the low n mode is electromagnetic. Frequency analysis shows that the high n mode is sometimes mixed with an ion instability. Experimental radial electric field is applied and its effects studied. We will also show some preliminary nonlinear results. We thank R. Groebner, P. Snyder and Y. Zheng for providing experimental profiles and helpful discussions.

Comparison of the Experimental Performance of Ferroelectric CPW Circuits with Method of Moment Simulations and Conformal Mapping

NASA Technical Reports Server (NTRS)

VanKeuls, Fred W.; Chevalier, Chris T.; Miranda, Felix A.; Carlson, C. M.; Rivkin, T. V.; Parilla, P. A.; Perkins, J. D.; Ginley, D. S.

2001-01-01

Experimental measurements of coplanar waveguide (CPW) circuits atop thin films of ferroelectric Ba(x)Sr(1-x)TiO3 (BST) were made as a function bias from 0 to 200 V and frequency from 0.045 to 20 GHz. The resulting phase shifts are compared with method of moments electromagnetic simulations and a conformal mapping analysis to determine the dielectric constant of the BST films. Based on the correlation between the experimental and the modeled data, an analysis of the extent to which the electromagnetic simulators provide reliable values for the dielectric constant of the ferroelectric in these structures has been performed. In addition, to determine how well the modeled data compare with experimental data, the dielectric constant values were also compared to low frequency measurements of interdigitated capacitor circuits on the same films. Results of these comparisons will be presented.

Innovative HPC architectures for the study of planetary plasma environments

NASA Astrophysics Data System (ADS)

Amaya, Jorge; Wolf, Anna; Lembège, Bertrand; Zitz, Anke; Alvarez, Damian; Lapenta, Giovanni

2016-04-01

DEEP-ER is an European Commission founded project that develops a new type of High Performance Computer architecture. The revolutionary system is currently used by KU Leuven to study the effects of the solar wind on the global environments of the Earth and Mercury. The new architecture combines the versatility of Intel Xeon computing nodes with the power of the upcoming Intel Xeon Phi accelerators. Contrary to classical heterogeneous HPC architectures, where it is customary to find CPU and accelerators in the same computing nodes, in the DEEP-ER system CPU nodes are grouped together (Cluster) and independently from the accelerator nodes (Booster). The system is equipped with a state of the art interconnection network, a highly scalable and fast I/O and a fail recovery resiliency system. The final objective of the project is to introduce a scalable system that can be used to create the next generation of exascale supercomputers. The code iPic3D from KU Leuven is being adapted to this new architecture. This particle-in-cell code can now perform the computation of the electromagnetic fields in the Cluster while the particles are moved in the Booster side. Using fast and scalable Xeon Phi accelerators in the Booster we can introduce many more particles per cell in the simulation than what is possible in the current generation of HPC systems, allowing to calculate fully kinetic plasmas with very low interpolation noise. The system will be used to perform fully kinetic, low noise, 3D simulations of the interaction of the solar wind with the magnetosphere of the Earth and Mercury. Preliminary simulations have been performed in other HPC centers in order to compare the results in different systems. In this presentation we show the complexity of the plasma flow around the planets, including the development of hydrodynamic instabilities at the flanks, the presence of the collision-less shock, the magnetosheath, the magnetopause, reconnection zones, the formation of the plasma sheet and the magnetotail, and the variation of ion/electron plasma flows when crossing these frontiers. The simulations also give access to detailed information about the particle dynamics and their velocity distribution at locations that can be used for comparison with satellite data.

Computationally efficient methods for modelling laser wakefield acceleration in the blowout regime

NASA Astrophysics Data System (ADS)

Cowan, B. M.; Kalmykov, S. Y.; Beck, A.; Davoine, X.; Bunkers, K.; Lifschitz, A. F.; Lefebvre, E.; Bruhwiler, D. L.; Shadwick, B. A.; Umstadter, D. P.; Umstadter

2012-08-01

Electron self-injection and acceleration until dephasing in the blowout regime is studied for a set of initial conditions typical of recent experiments with 100-terawatt-class lasers. Two different approaches to computationally efficient, fully explicit, 3D particle-in-cell modelling are examined. First, the Cartesian code vorpal (Nieter, C. and Cary, J. R. 2004 VORPAL: a versatile plasma simulation code. J. Comput. Phys. 196, 538) using a perfect-dispersion electromagnetic solver precisely describes the laser pulse and bubble dynamics, taking advantage of coarser resolution in the propagation direction, with a proportionally larger time step. Using third-order splines for macroparticles helps suppress the sampling noise while keeping the usage of computational resources modest. The second way to reduce the simulation load is using reduced-geometry codes. In our case, the quasi-cylindrical code calder-circ (Lifschitz, A. F. et al. 2009 Particle-in-cell modelling of laser-plasma interaction using Fourier decomposition. J. Comput. Phys. 228(5), 1803-1814) uses decomposition of fields and currents into a set of poloidal modes, while the macroparticles move in the Cartesian 3D space. Cylindrical symmetry of the interaction allows using just two modes, reducing the computational load to roughly that of a planar Cartesian simulation while preserving the 3D nature of the interaction. This significant economy of resources allows using fine resolution in the direction of propagation and a small time step, making numerical dispersion vanishingly small, together with a large number of particles per cell, enabling good particle statistics. Quantitative agreement of two simulations indicates that these are free of numerical artefacts. Both approaches thus retrieve the physically correct evolution of the plasma bubble, recovering the intrinsic connection of electron self-injection to the nonlinear optical evolution of the driver.

Geospace ionosphere research with a MF/HF radio instrument on a cubesat

NASA Astrophysics Data System (ADS)

Kallio, E. J.; Aikio, A. T.; Alho, M.; Fontell, M.; van Gijlswijk, R.; Kauristie, K.; Kestilä, A.; Koskimaa, P.; Makela, J. S.; Mäkelä, M.; Turunen, E.; Vanhamäki, H.

2016-12-01

Modern technology provides new possibilities to study geospace and its ionosphere, using spacecraft and and computer simulations. A type of nanosatellites, CubeSats, provide a cost effective possibility to provide in-situ measurements in the ionosphere. Moreover, combined CubeSat observations with ground-based observations gives a new view on auroras and associated electromagnetic phenomena. Especially joint and active CubeSat - ground based observation campaigns enable the possibility of studying the 3D structure of the ionosphere. Furthermore using several CubeSats to form satellite constellations enables much higher temporal resolution. At the same time, increasing computation capacity has made it possible to perform simulations where properties of the ionosphere, such as propagation of the electromagnetic waves in the medium frequency, MF (0.3-3 MHz) and high frequency, HF (3-30 MHz), ranges is based on a 3D ionospheric model and on first-principles modelling. Electromagnetic waves at those frequencies are strongly affected by ionospheric electrons and, consequently, those frequencies can be used for studying the plasma. On the other hand, even if the ionosphere originally enables long-range telecommunication at MF and HF frequencies, the frequent occurrence of spatiotemporal variations in the ionosphere disturbs communication channels, especially at high latitudes. Therefore, study of the MF and HF waves in the ionosphere has both a strong science and technology interests. We present computational simulation results and measuring principles and techniques to investigate the arctic ionosphere by a polar orbiting CubeSat whose novel AM radio instrument measures HF and MF waves. The cubesat, which contains also a white light aurora camera, is planned to be launched in 2017 (http://www.suomi100satelliitti.fi/eng). We have modelled the propagation of the radio waves, both ground generated man-made waves and space formed space weather related waves, through the 3D arctic ionosphere with (1) a new 3D ray tracing model and (2) a new 3D full kinetic electromagnetic simulation. These simulations are used to analyse the origin of the radio waves observed by the MH/HF radio instrument and, consequently, to derive information about the 3D ionosphere and its spatial and temporal variations.

Solar radio emissions: 2D full PIC simulations

NASA Astrophysics Data System (ADS)

Pierre, H.; Sgattoni, A.; Briand, C.; Amiranoff, F.; Riconda, C.

2016-12-01

Solar radio emissions are electromagnetic waves observed at the local plasma frequency and/or at twice the plasma frequency. To describe their origin a multi-stage model has been proposed by Ginzburg & Zhelezniakov (1958) and further developed by several authors, which consider a succession of non-linear three-wave interaction processes. Electron beams accelerated by solar flares travel in the interplanetary plasma and provide the free energy for the development of plasma instabilities. The model describes how part of the free energy of these beams can be transformed in a succession of plasma waves and eventually into electromagnetic waves. Following the work of Thurgood & Tsiklauri (2015) we performed several 2D Particle In Cell simulations. The simulations follow the entire set of processes from the electron beam propagation in the background plasma to the generation of the electromagnetic waves in particular the 2ωp emission, including the excitation of the low frequency waves. As suggested by Thurgood & Tsiklauri (2015) it is possible to identify regimes where the radiation emission can be directly linked to the electron beams. Our attention was devoted to estimate the conversion efficiency from electron kinetic energy to the em energy, and the growth rate of the several processes which can be identified. We studied the emission angles of the 2ωpradiation and compared them with the theoretical predictions of Willes et. al. (1995). We also show the role played by some numerical parameters i.e. the size and shape of the simulation box. This work is the first step to prepare laser-plasma experiments. V. L. Ginzburg, V. V. Zhelezniakov On the Possible Mechanisms of Sporadic Solar Radio Emission (Radiation in an Isotropic Plasma) Soviet Astronomy, Vol. 2, p.653 (1958) J. O. Thurgood and D. Tsiklauri Self-consistent particle-in-cell simulations of funda- mental and harmonic plasma radio emission mechanisms. Astronomy & Astrophysics 584, A83 (2015). A. Willes, P. Robinson and D. Melrose (1995). Second harmonic electromagnetic emis- sion via Langmuir wave coalescence. Physics of Plasmas, 3(1), 149-159 (1995).

Center for the Study of Plasma Microturbulence

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

Parker, Scott E.

We have discovered a possible "natural fueling" mechanism in tokamak fusion reactors using large scale gyrokinetic turbulence simulation. In the presence of a heat flux dominated tokamak plasma, cold ions naturally pinch radially inward. If cold DT fuel is introduced near the edge using shallow pellet injection, the cold fuel will pinch inward, at the expense of hot helium ash going radially outward. By adjusting the cold DT fuel concentration, the core DT density profiles can be maintained. We have also shown that cold source ions from edge recycling of cold neutrals are pinched radially inward. This mechanism may bemore » important for fully understanding the edge pedestal buildup after an ELM crash. Work includes benchmarking the gyrokinetic turbulence codes in the electromagnetic regime. This includes cyclone base case parameters with an increasing plasma beta. The code comparisons include GEM, GYRO and GENE. There is good linear agreement between the codes using the Cyclone base case, but including electromagnetics and scanning the plasma beta. All the codes have difficulty achieving nonlinear saturation as the kinetic ballooning limit is approached. GEM does not saturate well when beta gets above about 1/2 of the ideal ballooning limit. We find that the lack of saturation is due to the long wavelength k{sub y} modes being nonlinearly pumped to high levels. If the fundamental k{sub y} mode is zeroed out, higher values of beta nonlinearly saturate well. Additionally, there have been studies to better understand CTEM nonlinear saturation and the importance of zonal flows. We have continued our investigation of trapped electron mode (TEM) turbulence. More recently, we have focused on the nonlinear saturation of TEM turbulence. An important feature of TEM is that in many parameter regimes, the zonal flow is unimportant. We find that when zonal flows are unimportant, zonal density is the dominant saturation mechanism. We developed a simple theory that agrees with the simulation and predicts zonal density generation and feedback stabilization of the most unstable mode even in the absence of zonal flow. We are using GEM to simulate NSTX discharges. We have also done verification and validation on DIII-D. Good agreement with GYRO and DIII-D flux levels were reported in the core region.« less

Nonlinear saturation of the slab ITG instability and zonal flow generation with fully kinetic ions

NASA Astrophysics Data System (ADS)

Miecnikowski, Matthew T.; Sturdevant, Benjamin J.; Chen, Yang; Parker, Scott E.

2018-05-01

Fully kinetic turbulence models are of interest for their potential to validate or replace gyrokinetic models in plasma regimes where the gyrokinetic expansion parameters are marginal. Here, we demonstrate fully kinetic ion capability by simulating the growth and nonlinear saturation of the ion-temperature-gradient instability in shearless slab geometry assuming adiabatic electrons and including zonal flow dynamics. The ion trajectories are integrated using the Lorentz force, and the cyclotron motion is fully resolved. Linear growth and nonlinear saturation characteristics show excellent agreement with analogous gyrokinetic simulations across a wide range of parameters. The fully kinetic simulation accurately reproduces the nonlinearly generated zonal flow. This work demonstrates nonlinear capability, resolution of weak gradient drive, and zonal flow physics, which are critical aspects of modeling plasma turbulence with full ion dynamics.

[Study on effects of bioelectric parameters of rats in electromagnetic radiation of HV transmission line].

PubMed

Zhang, Anying; Pang, Xiaofeng; Yuan, Ping

2007-02-01

With the development of economy and coming of information era, the chance of exposure to electromagnetic fields with various frequencies has been increased for every human. The effects of electromagnetic radiattion on human being's health are versatile. To study the effects of bioelctronic parameters of rats in the electromagnetic radiations of HV transmission line, EEG, ECG and CMAP were measured in rats exposed to simulating high-voltage transmission line electromagnetic radiation for over one year. Brain tissues were studied by Fourier transform infrared spectroscopy. The results showed that no significant difference between exposed group and control group in EEG; however the FT-infrared spectra of brain tissues were different; the ECG of the exposed animals was considerably altered. Significant slowing of heart rate was observed in those rates exposed to EMFs; the latent period of CMAP in exposed group were not different compared with those of control group however there was a significant difference in wave amplitude of CMAP between the exposed group and control group. All results indicated that there must be some effects on bioelectric parameters of rats exposed to electromagnetic radiation of high-voltage transmission line for a long time.

Coupled Hydromechanical and Electromagnetic Responses in Unsaturated Porous Media: Theory, Observation, and Numerical Simulations

NASA Astrophysics Data System (ADS)

Mahardika, Harry

Hydromechanical energy can be partially converted into electromagnetic energy due to electrokinetic effect, where mechanical energy causes the relative displacement of the charged pore water with respect to the solid skeleton of the porous material and generated electrical current density. An application of this phenomenon is seismoelectric method, a geophysical method in which electromagnetic signals are recorded and associated with the propagation of seismic waves. Due to its coupling nature, seismoelectric method promises advantages in characterizing the subsurface properties and geometry compared to independent employments of seismic or electromagnetic acquisition alone. Since the recorded seismoelectric signal are sensitive to water content changes this method have been applied for groundwater studies to delineates vadoze zone-aquifer boundary since the last twenty years. The problem, however, the existing governing equations of coupled seismic and electromagnetic are not accounted for unsaturated conditions and its petrophysical sensitivity to water content. In this thesis we extend the applications of seismoelectric method for unsaturated porous medium for several geophysical problems. (1) We begin our study with numerical study to localize and characterize a seismic event induced by hydraulic fracturing operation sedimentary rocks. In this problem, we use the fully-saturated case of seismoelectric method and we propose a new joint inversion scheme (seismic and seismoelectric) to determine the position and moment tensor that event. (2) We expand the seismoelectric theory for unsaturated condition and show that the generation of electrical current density are depend on several important petrophysical properties that are sensitive to water content. This new expansion of governing equation provide us theory for developing a new approach for seismoelectric method to image the oil water encroachment front during water flooding of an oil reservoir or an aquifer contaminated with DNAPL. (3) Next, we present a test case which is the first-attempt analysis of seismoelectric sounding measurements done on glacial environment of Glacier de Tsanfleuron through numerical forward modeling. Here we treat the snow-glacial environment similar as with vadoze zone-aquifer zone in unsaturated porous medium. (4) The modified governing equations also provides us foundations to do another case study, which is characterization of seismoelectrical events generated from water content changes in the vadoze zone measured using seismoelectric sounding from NE England. (5) We finalize the thesis with an interpretation of electrical signal generated from water injection experiment done on the top two meter of the soil surface (vadoze zone) using inverse calculation presented on the first topic of the thesis. The fundamental research presented on this thesis hopefully provides a basis for further advancement on seismoelectric or joint seismic-electrical methods for applications ranging from hydrogeology, volcanology and geothermal energy, and oil and gas cases.

Numerical studies of fast ion slowing down rates in cool magnetized plasma using LSP

NASA Astrophysics Data System (ADS)

Evans, Eugene S.; Kolmes, Elijah; Cohen, Samuel A.; Rognlien, Tom; Cohen, Bruce; Meier, Eric; Welch, Dale R.

2016-10-01

In MFE devices, rapid transport of fusion products from the core into the scrape-off layer (SOL) could perform the dual roles of energy and ash removal. The first-orbit trajectories of most fusion products from small field-reversed configuration (FRC) devices will traverse the SOL, allowing those particles to deposit their energy in the SOL and be exhausted along the open field lines. Thus, the fast ion slowing-down time should affect the energy balance of an FRC reactor and its neutron emissions. However, the dynamics of fast ion energy loss processes under the conditions expected in the FRC SOL (with ρe <λDe) are analytically complex, and not yet fully understood. We use LSP, a 3D electromagnetic PIC code, to examine the effects of SOL density and background B-field on the slowing-down time of fast ions in a cool plasma. As we use explicit algorithms, these simulations must spatially resolve both ρe and λDe, as well as temporally resolve both Ωe and ωpe, increasing computation time. Scaling studies of the fast ion charge (Z) and background plasma density are in good agreement with unmagnetized slowing down theory. Notably, Z-scaling represents a viable way to dramatically reduce the required CPU time for each simulation. This work was supported, in part, by DOE Contract Number DE-AC02-09CH11466.

Direct observation of turbulent magnetic fields in hot, dense laser produced plasmas

PubMed Central

Mondal, Sudipta; Narayanan, V.; Ding, Wen Jun; Lad, Amit D.; Hao, Biao; Ahmad, Saima; Wang, Wei Min; Sheng, Zheng Ming; Sengupta, Sudip; Kaw, Predhiman; Das, Amita; Kumar, G. Ravindra

2012-01-01

Turbulence in fluids is a ubiquitous, fascinating, and complex natural phenomenon that is not yet fully understood. Unraveling turbulence in high density, high temperature plasmas is an even bigger challenge because of the importance of electromagnetic forces and the typically violent environments. Fascinating and novel behavior of hot dense matter has so far been only indirectly inferred because of the enormous difficulties of making observations on such matter. Here, we present direct evidence of turbulence in giant magnetic fields created in an overdense, hot plasma by relativistic intensity (1018W/cm2) femtosecond laser pulses. We have obtained magneto-optic polarigrams at femtosecond time intervals, simultaneously with micrometer spatial resolution. The spatial profiles of the magnetic field show randomness and their k spectra exhibit a power law along with certain well defined peaks at scales shorter than skin depth. Detailed two-dimensional particle-in-cell simulations delineate the underlying interaction between forward currents of relativistic energy “hot” electrons created by the laser pulse and “cold” return currents of thermal electrons induced in the target. Our results are not only fundamentally interesting but should also arouse interest on the role of magnetic turbulence induced resistivity in the context of fast ignition of laser fusion, and the possibility of experimentally simulating such structures with respect to the sun and other stellar environments. PMID:22566660

The Liquid Argon Software Toolkit (LArSoft): Goals, Status and Plan

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

Pordes, Rush; Snider, Erica

LArSoft is a toolkit that provides a software infrastructure and algorithms for the simulation, reconstruction and analysis of events in Liquid Argon Time Projection Chambers (LArTPCs). It is used by the ArgoNeuT, LArIAT, MicroBooNE, DUNE (including 35ton prototype and ProtoDUNE) and SBND experiments. The LArSoft collaboration provides an environment for the development, use, and sharing of code across experiments. The ultimate goal is to develop fully automatic processes for reconstruction and analysis of LArTPC events. The toolkit is based on the art framework and has a well-defined architecture to interface to other packages, including to GEANT4 and GENIE simulation softwaremore » and the Pandora software development kit for pattern recognition. It is designed to facilitate and support the evolution of algorithms including their transition to new computing platforms. The development of the toolkit is driven by the scientific stakeholders involved. The core infrastructure includes standard definitions of types and constants, means to input experiment geometries as well as meta and event- data in several formats, and relevant general utilities. Examples of algorithms experiments have contributed to date are: photon-propagation; particle identification; hit finding, track finding and fitting; electromagnetic shower identification and reconstruction. We report on the status of the toolkit and plans for future work.« less

Direct observation of turbulent magnetic fields in hot, dense laser produced plasmas.

PubMed

Mondal, Sudipta; Narayanan, V; Ding, Wen Jun; Lad, Amit D; Hao, Biao; Ahmad, Saima; Wang, Wei Min; Sheng, Zheng Ming; Sengupta, Sudip; Kaw, Predhiman; Das, Amita; Kumar, G Ravindra

2012-05-22

Turbulence in fluids is a ubiquitous, fascinating, and complex natural phenomenon that is not yet fully understood. Unraveling turbulence in high density, high temperature plasmas is an even bigger challenge because of the importance of electromagnetic forces and the typically violent environments. Fascinating and novel behavior of hot dense matter has so far been only indirectly inferred because of the enormous difficulties of making observations on such matter. Here, we present direct evidence of turbulence in giant magnetic fields created in an overdense, hot plasma by relativistic intensity (10(18) W/cm(2)) femtosecond laser pulses. We have obtained magneto-optic polarigrams at femtosecond time intervals, simultaneously with micrometer spatial resolution. The spatial profiles of the magnetic field show randomness and their k spectra exhibit a power law along with certain well defined peaks at scales shorter than skin depth. Detailed two-dimensional particle-in-cell simulations delineate the underlying interaction between forward currents of relativistic energy "hot" electrons created by the laser pulse and "cold" return currents of thermal electrons induced in the target. Our results are not only fundamentally interesting but should also arouse interest on the role of magnetic turbulence induced resistivity in the context of fast ignition of laser fusion, and the possibility of experimentally simulating such structures with respect to the sun and other stellar environments.

Simulations of relativistic quantum plasmas using real-time lattice scalar QED

NASA Astrophysics Data System (ADS)

Shi, Yuan; Xiao, Jianyuan; Qin, Hong; Fisch, Nathaniel J.

2018-05-01

Real-time lattice quantum electrodynamics (QED) provides a unique tool for simulating plasmas in the strong-field regime, where collective plasma scales are not well separated from relativistic-quantum scales. As a toy model, we study scalar QED, which describes self-consistent interactions between charged bosons and electromagnetic fields. To solve this model on a computer, we first discretize the scalar-QED action on a lattice, in a way that respects geometric structures of exterior calculus and U(1)-gauge symmetry. The lattice scalar QED can then be solved, in the classical-statistics regime, by advancing an ensemble of statistically equivalent initial conditions in time, using classical field equations obtained by extremizing the discrete action. To demonstrate the capability of our numerical scheme, we apply it to two example problems. The first example is the propagation of linear waves, where we recover analytic wave dispersion relations using numerical spectrum. The second example is an intense laser interacting with a one-dimensional plasma slab, where we demonstrate natural transition from wakefield acceleration to pair production when the wave amplitude exceeds the Schwinger threshold. Our real-time lattice scheme is fully explicit and respects local conservation laws, making it reliable for long-time dynamics. The algorithm is readily parallelized using domain decomposition, and the ensemble may be computed using quantum parallelism in the future.

Quantum resonances of Landau damping in the electromagnetic response of metallic nanoslabs.

PubMed

Castillo-López, S G; Makarov, N M; Pérez-Rodríguez, F

2018-05-15

The resonant quantization of Landau damping in far-infrared absorption spectra of metal nano-thin films is predicted within the Kubo formalism. Specifically, it is found that the discretization of the electromagnetic and electron wave numbers inside a metal nanoslab produces quantum nonlocal resonances well-resolved at slab thicknesses smaller than the electromagnetic skin depth. Landau damping manifests itself precisely as such resonances, tracing the spectral curve obtained within the semiclassical Boltzmann approach. For slab thicknesses much greater than the skin depth, the classical regime emerges. Here the results of the quantum model and the Boltzmann approach coincide. Our analytical study is in perfect agreement with corresponding numerical simulations.

Modeling of MOEMS electromagnetic scanning grating mirror for NIR micro-spectrometer

NASA Astrophysics Data System (ADS)

Zhou, Ying; Wen, Quan; Wen, Zhiyu; Yang, Tingyan

2016-02-01

In this paper, the mathematical model is developed for researching the detailed electromagnetic mechanism of MOEMS scanning mirror. We present the relationship between spectral range and optical scanning angle. Furthermore, the variation tendencies of resonant frequency and maximal torsional angle are studied in detail under different aspect ratios of MOEMS scanning mirror and varied dimensions of torsional bar. The numerical results and Finite Element Analysis simulations both indicate that the thickness of torsional bar is the most important factor. The maximal torsional angle appears when the aspect ratio equals to 1. This mathematical model is an effective way for designing the MOEMS electromagnetic scanning grating mirror in actual fabrication.

Wound diagnostics with microwaves.

PubMed

Schertlen, Ralph; Pivit, Florian; Wiesbeck, Werner

2002-01-01

The reflection of electromagnetic waves on material surfaces is very depending on the electric and magnetic properties of these materials, on their structure and on the surface texture. Therefore the different layers and dielectric properties of healthy and unsound body tissue also show different reflection behavior towards incidentating electromagnetic waves. By analyzing the reflected signals of incident electromagnetic waves, it is possible to get information about the inner structure of the reflecting body tissue. This effect could then be used for a contactless analysis of body tissue e.g. to gain crucial medical information about healing processes. In this paper the results of several full wave simulations of various tissue structures are presented and the significance and usability of this method is shown.

Polarization-independent electromagnetically induced transparency-like metasurface

NASA Astrophysics Data System (ADS)

Jia, Xiuli; Wang, Xiaoou

2018-01-01

A classical electromagnetically induced transparency-like (EIT-like) metasurface is numerically simulated. This metasurface is composed of two identical and orthogonal double-end semitoroidals (DESTs) metal resonators. Under the excitation of the normal incidence waves, each of the two DESTs structure exhibits electromagnetic dipole responses at different frequencies, which leads to the polarization-independent EIT-like effect. The features of the EIT-like effect are qualitatively analyzed based on the surface current and magnetic field distribution. In addition, the large index is extracted to verify the slow-light property within the transmission window. The EIT-like metasurface structure with the above-mentioned characteristics may have potential applications in some areas, such as sensing, slow light, and filtering devices.

Dual symmetry in a generalized Maxwell theory

NASA Astrophysics Data System (ADS)

Brandt, F. T.; Frenkel, J.; McKeon, D. G. C.

2016-09-01

We examine Podolsky’s electrodynamics, which is non-invariant under the usual duality transformation. We deduce a generalization of Hodge’s star duality, which leads to a dual gauge field and restores to a certain extent the dual symmetry. The model becomes fully dual symmetric asymptotically, when it reduces to the Maxwell theory. We argue that this strict dual symmetry directly implies the existence of the basic invariants of the electromagnetic fields.

Rapid Ultrasonic Inspection of Artillery Projectiles

DTIC Science & Technology

1980-11-01

field behavior as a function of gap separation d 26 Fig. 14 Electromagnet equivalent circuit model use for final design of yoke, pole pieces and...card 64 Fig. 37 Frequency response of receiver circuit 66 Fig. 38 a) Configuration of EMAT used to launch both longitudinal and circumferential... circuit for OD and ID location 88 Fig. 51 Photograph of fully assembled EMAT inspection system during projectile inspection 92 Fig. 52 Sequence

Numerical simulation for the magnetic force distribution in electromagnetic forming of small size flat sheet

NASA Astrophysics Data System (ADS)

Chen, Xiaowei; Wang, Wenping; Wan, Min

2013-12-01

It is essential to calculate magnetic force in the process of studying electromagnetic flat sheet forming. Calculating magnetic force is the basis of analyzing the sheet deformation and optimizing technical parameters. Magnetic force distribution on the sheet can be obtained by numerical simulation of electromagnetic field. In contrast to other computing methods, the method of numerical simulation has some significant advantages, such as higher calculation accuracy, easier using and other advantages. In this paper, in order to study of magnetic force distribution on the small size flat sheet in electromagnetic forming when flat round spiral coil, flat rectangular spiral coil and uniform pressure coil are adopted, the 3D finite element models are established by software ANSYS/EMAG. The magnetic force distribution on the sheet are analyzed when the plane geometries of sheet are equal or less than the coil geometries under fixed discharge impulse. The results showed that when the physical dimensions of sheet are less than the corresponding dimensions of the coil, the variation of induced current channel width on the sheet will cause induced current crowding effect that seriously influence the magnetic force distribution, and the degree of inhomogeneity of magnetic force distribution is increase nearly linearly with the variation of induced current channel width; the small size uniform pressure coil will produce approximately uniform magnetic force distribution on the sheet, but the coil is easy to early failure; the desirable magnetic force distribution can be achieved when the unilateral placed flat rectangular spiral coil is adopted, and this program can be take as preferred one, because the longevity of flat rectangular spiral coil is longer than the working life of small size uniform pressure coil.

Apparent resistivity for transient electromagnetic induction logging and its correction in radial layer identification

NASA Astrophysics Data System (ADS)

Meng, Qingxin; Hu, Xiangyun; Pan, Heping; Xi, Yufei

2018-04-01

We propose an algorithm for calculating all-time apparent resistivity from transient electromagnetic induction logging. The algorithm is based on the whole-space transient electric field expression of the uniform model and Halley's optimisation. In trial calculations for uniform models, the all-time algorithm is shown to have high accuracy. We use the finite-difference time-domain method to simulate the transient electromagnetic field in radial two-layer models without wall rock and convert the simulation results to apparent resistivity using the all-time algorithm. The time-varying apparent resistivity reflects the radially layered geoelectrical structure of the models and the apparent resistivity of the earliest time channel follows the true resistivity of the inner layer; however, the apparent resistivity at larger times reflects the comprehensive electrical characteristics of the inner and outer layers. To accurately identify the outer layer resistivity based on the series relationship model of the layered resistance, the apparent resistivity and diffusion depth of the different time channels are approximately replaced by related model parameters; that is, we propose an apparent resistivity correction algorithm. By correcting the time-varying apparent resistivity of radial two-layer models, we show that the correction results reflect the radially layered electrical structure and the corrected resistivities of the larger time channels follow the outer layer resistivity. The transient electromagnetic fields of radially layered models with wall rock are simulated to obtain the 2D time-varying profiles of the apparent resistivity and corrections. The results suggest that the time-varying apparent resistivity and correction results reflect the vertical and radial geoelectrical structures. For models with small wall-rock effect, the correction removes the effect of the low-resistance inner layer on the apparent resistivity of the larger time channels.

BMFO-PVDF electrospun fiber based tunable metamaterial structures for electromagnetic interference shielding in microwave frequency region

NASA Astrophysics Data System (ADS)

Revathi, Venkatachalam; Dinesh Kumar, Sakthivel; Subramanian, Venkatachalam; Chellamuthu, Muthamizhchelvan

2015-11-01

Metamaterial structures are artificial structures that are useful in controlling the flow of electromagnetic radiation. In this paper, composite fibers of sub-micron thickness of barium substituted magnesium ferrite (Ba0.2Mg0.8Fe2O4) - polyvinylidene fluoride obtained by electrospinning is used as a substrate to design electromagnetic interference shielding structures. While electrospinning improves the ferroelectric properties of the polyvinylidene fluoride, the presence of barium magnesium ferrite modifies the magnetic property of the composite fiber. The dielectric and magnetic properties at microwave frequency measured using microwave cavity perturbation technique are used to design the reflection as well as absorption based tunable metamaterial structures for electromagnetic interference shielding in microwave frequency region. For one of the structures, the simulation indicates that single negative metamaterial structure becomes a double negative metamaterial under the external magnetic field.

A comparison of lightning and nuclear electromagnetic pulse response of tactical shelters

NASA Technical Reports Server (NTRS)

Perala, R. A.; Rudolph, T. H.; Mckenna, P. M.

1984-01-01

The internal response (electromagnetic fields and cable responses) of tactical shelters is addressed. Tactical shelters are usually well-shielded systems. Apart from penetrations by signal and power lines, the main leakage paths to the interior are via seams and the environment control unit (ECU) honeycomb filter. The time domain in three-dimensional finite-difference technique is employed to determine the external and internal coupling to a shelter excited by nuclear electromagnetic pulses (NEMP) and attached lightning. The responses of interest are the internal electromagnetic fields and the voltage, current, power, and energy coupled to internal cables. Leakage through the seams and ECU filter is accomplished by their transfer impedances which relate internal electric fields to external current densities. Transfer impedances which were experimentally measured are used in the analysis. The internal numerical results are favorably compared to actual shelter test data under simulated NEMP illumination.

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.

Massive Black Hole Mergers: Can we see what LISA will hear?

NASA Technical Reports Server (NTRS)

Centrella, Joan

2009-01-01

Coalescing massive black hole binaries are formed when galaxies merge. The final stages of this coalescence produce strong gravitational wave signals that can be detected by the space-borne LISA. When the black holes merge in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. Modeling such electromagnetic counterparts requires evolving the behavior of both gas and fields in the strong-field regions around the black holes. We have taken a first step towards this problem by mapping the flow of pressureless matter in the dynamic, 3-D general relativistic spacetime around the merging black holes. We report on the results of these initial simulations and discuss their likely importance for future hydrodynamical simulations.

First experience of vectorizing electromagnetic physics models for detector simulation

NASA Astrophysics Data System (ADS)

Amadio, G.; Apostolakis, J.; Bandieramonte, M.; Bianchini, C.; Bitzes, G.; Brun, R.; Canal, P.; Carminati, F.; de Fine Licht, J.; Duhem, L.; Elvira, D.; Gheata, A.; Jun, S. Y.; Lima, G.; Novak, M.; Presbyterian, M.; Shadura, O.; Seghal, R.; Wenzel, S.

2015-12-01

The recent emergence of hardware architectures characterized by many-core or accelerated processors has opened new opportunities for concurrent programming models taking advantage of both SIMD and SIMT architectures. The GeantV vector prototype for detector simulations has been designed to exploit both the vector capability of mainstream CPUs and multi-threading capabilities of coprocessors including NVidia GPUs and Intel Xeon Phi. The characteristics of these architectures are very different in terms of the vectorization depth, parallelization needed to achieve optimal performance or memory access latency and speed. An additional challenge is to avoid the code duplication often inherent to supporting heterogeneous platforms. In this paper we present the first experience of vectorizing electromagnetic physics models developed for the GeantV project.

GEANT4 Tuning For pCT Development

NASA Astrophysics Data System (ADS)

Yevseyeva, Olga; de Assis, Joaquim T.; Evseev, Ivan; Schelin, Hugo R.; Paschuk, Sergei A.; Milhoretto, Edney; Setti, João A. P.; Díaz, Katherin S.; Hormaza, Joel M.; Lopes, Ricardo T.

2011-08-01

Proton beams in medical applications deal with relatively thick targets like the human head or trunk. Thus, the fidelity of proton computed tomography (pCT) simulations as a tool for proton therapy planning depends in the general case on the accuracy of results obtained for the proton interaction with thick absorbers. GEANT4 simulations of proton energy spectra after passing thick absorbers do not agree well with existing experimental data, as showed previously. Moreover, the spectra simulated for the Bethe-Bloch domain showed an unexpected sensitivity to the choice of low-energy electromagnetic models during the code execution. These observations were done with the GEANT4 version 8.2 during our simulations for pCT. This work describes in more details the simulations of the proton passage through aluminum absorbers with varied thickness. The simulations were done by modifying only the geometry in the Hadrontherapy Example, and for all available choices of the Electromagnetic Physics Models. As the most probable reasons for these effects is some specific feature in the code, or some specific implicit parameters in the GEANT4 manual, we continued our study with version 9.2 of the code. Some improvements in comparison with our previous results were obtained. The simulations were performed considering further applications for pCT development.

Upset susceptibility study employing circuit analysis and digital simulation. [digital systems and electromagnetic interference

NASA Technical Reports Server (NTRS)

Carreno, V. A.

1984-01-01

An approach to predict the susceptibility of digital systems to signal disturbances is described. Electrical disturbances on a digital system's input and output lines can be induced by activities and conditions including static electricity, lightning discharge, electromagnetic interference (EMI), and electromagnetic pulsation (EMP). The electrical signal disturbances employed for the susceptibility study were limited to nondestructive levels, i.e., the system does not sustain partial or total physical damage and reset and/or reload brings the system to an operational status. The front-end transition from the electrical disturbances to the equivalent digital signals was accomplished by computer-aided circuit analysis. The super-sceptre (system for circuit evaluation of transient radiation effects) programs was used. Gate models were developed according to manufacturers' performance specifications and parameters resulting from construction processes characteristic of the technology. Digital simulation at the gate and functional level was employed to determine the impact of the abnormal signals on system performance and to study the propagation characteristics of these signals through the system architecture. Example results are included for an Intel 8080 processor configuration.

Numerical modelling of GPR electromagnetic fields for locating burial sites

NASA Astrophysics Data System (ADS)

Carcione, José M.; Karczewski, Jerzy; Mazurkiewicz, Ewelina; Tadeusiewicz, Ryszard; Tomecka-Suchoń, Sylwia

2017-11-01

Ground-penetrating radar (GPR) is commonly used for locating burial sites. In this article, we acquired radargrams at a site where a domestic pig cadaver was buried. The measurements were conducted with the ProEx System GPR manufactured by the Swedish company Mala Geoscience with an antenna of 500MHz. The event corresponding to the pig can be clearly seen in the measurements. In order to improve the interpretation, the electromagnetic field is compared to numerical simulations computed with the pseudo-spectral Fourier method. A geological model has been defined on the basis of assumed electromagnetic properties (permittivity, conductivity and magnetic permeability). The results, when compared with the GPR measurements, show a dissimilar amplitude behaviour, with a stronger reflection event from the bottom of the pit. We have therefore performed another simulation by decreasing the electrical conductivity of the body very close to that of air. The comparison improved, showing more reflections, which could be an indication that the body contains air or has been degraded to a certain extent that the electrical resistivity has greatly increased.

THE HYDROGEN EPOCH OF REIONIZATION ARRAY DISH. II. CHARACTERIZATION OF SPECTRAL STRUCTURE WITH ELECTROMAGNETIC SIMULATIONS AND ITS SCIENCE IMPLICATIONS

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

Ewall-Wice, Aaron; Hewitt, Jacqueline; Neben, Abraham R.

We use time-domain electromagnetic simulations to determine the spectral characteristics of the Hydrogen Epoch of Reionization Arrays (HERA) antenna. These simulations are part of a multi-faceted campaign to determine the effectiveness of the dish’s design for obtaining a detection of redshifted 21 cm emission from the epoch of reionization. Our simulations show the existence of reflections between HERA’s suspended feed and its parabolic dish reflector that fall below -40 dB at 150 ns and, for reasonable impedance matches, have a negligible impact on HERA’s ability to constrain EoR parameters. It follows that despite the reflections they introduce, dishes are effectivemore » for increasing the sensitivity of EoR experiments at a relatively low cost. We find that electromagnetic resonances in the HERA feed’s cylindrical skirt, which is intended to reduce cross coupling and beam ellipticity, introduces significant power at large delays (-40 dB at 200 ns), which can lead to some loss of measurable Fourier modes and a modest reduction in sensitivity. Even in the presence of this structure, we find that the spectral response of the antenna is sufficiently smooth for delay filtering to contain foreground emission at line-of-sight wave numbers below k {sub ∥} ≲ 0.2 h Mpc{sup -1}, in the region where the current PAPER experiment operates. Incorporating these results into a Fisher Matrix analysis, we find that the spectral structure observed in our simulations has only a small effect on the tight constraints HERA can achieve on parameters associated with the astrophysics of reionization.« less

Differences in 1D electron plasma wake field acceleration in MeV versus GeV and linear versus blowout regimes

NASA Astrophysics Data System (ADS)

Tsiklauri, David

2018-03-01

In some laboratory and most astrophysical situations, plasma wake-field acceleration of electrons is one dimensional, i.e., variation transverse to the beam's motion can be ignored. Thus, one dimensional, particle-in-cell (PIC), fully electromagnetic simulations of electron plasma wake field acceleration are conducted in order to study the differences in electron plasma wake field acceleration in MeV versus GeV and linear versus blowout regimes. First, we show that caution needs to be taken when using fluid simulations, as PIC simulations prove that an approximation for an electron bunch not to evolve in time for a few hundred plasma periods only applies when it is sufficiently relativistic. This conclusion is true irrespective of the plasma temperature. We find that in the linear regime and GeV energies, the accelerating electric field generated by the plasma wake is similar to the linear and MeV regimes. However, because GeV energy driving bunch stays intact for a much longer time, the final acceleration energies are much larger in the GeV energies case. In the GeV energy range and blowout regime, the wake's accelerating electric field is much larger in amplitude compared with the linear case and also plasma wake geometrical size is much larger. Thus, the correct positioning of the trailing bunch is needed to achieve the efficient acceleration. For the considered case, optimally, there should be approximately (90-100)c/ωpe distance between the trailing and driving electron bunches in the GeV blowout regime.

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.

Exploiting Glide Symmetry in Planar EBG Structures

NASA Astrophysics Data System (ADS)

Mouris, Boules A.; Quevedo-Teruel, Oscar; Thobaben, Ragnar

2018-02-01

Periodic structures such as electromagnetic band gap (EBG) structures can be used to prevent the propagation of electromagnetic waves within a certain frequency range known as the stop band. One of the main limitations of using EBG structures at low frequencies is their relatively large size. In this paper, we investigate the possibility of using glide symmetry in planar EBG structures to reduce their size. Simulated results demonstrate that exploiting glide symmetry in EBG structures can lead to size reduction.

Behavioral and Biological Effects of Resonant Electromagnetic Absorption in Rats.

DTIC Science & Technology

1976-11-01

for 23-550 MHz, biological phantom materials to simulate tissue properties, monopole -above-ground radiation chamber, design of a waveguide slot array...Resonant Electromagnetic Power Absorption in Rats" L T OF FTCTIF S A,’L i .LIS SFigure Pa 1 A photograiph of the monopole -above-gruund radiation...and mice without ground effects (L/2b = 3.25 where 21Tb is the "average" circumference of the animals) ........ .................... ... 20 8

Three-dimensional numerical modeling of full-space transient electromagnetic responses of water in goaf

NASA Astrophysics Data System (ADS)

Chang, Jiang-Hao; Yu, Jing-Cun; Liu, Zhi-Xin

2016-09-01

The full-space transient electromagnetic response of water-filled goaves in coal mines were numerically modeled. Traditional numerical modeling methods cannot be used to simulate the underground full-space transient electromagnetic field. We used multiple transmitting loops instead of the traditional single transmitting loop to load the transmitting loop into Cartesian grids. We improved the method for calculating the z-component of the magnetic field based on the characteristics of full space. Then, we established the fullspace 3D geoelectrical model using geological data for coalmines. In addition, the transient electromagnetic responses of water-filled goaves of variable shape at different locations were simulated by using the finite-difference time-domain (FDTD) method. Moreover, we evaluated the apparent resistivity results. The numerical modeling results suggested that the resistivity differences between the coal seam and its roof and floor greatly affect the distribution of apparent resistivity, resulting in nearly circular contours with the roadway head at the center. The actual distribution of apparent resistivity for different geoelectrical models of water in goaves was consistent with the models. However, when the goaf water was located in one side, a false low-resistivity anomaly would appear on the other side owing to the full-space effect but the response was much weaker. Finally, the modeling results were subsequently confirmed by drilling, suggesting that the proposed method was effective.

Electromagnetic characteristics of systems of prolate and oblate ellipsoids

NASA Astrophysics Data System (ADS)

Karimi, Pouyan; Amiri-Hezaveh, Amirhossein; Ostoja-Starzewski, Martin; Jin, Jian-Ming

2017-11-01

The present study suggests a novel model for simulating electromagnetic characteristics of spheroidal nanofillers. The electromagnetic interference shielding efficiency of prolate and oblate ellipsoids in the X-band frequency range is studied. Different multilayered nanocomposite configurations incorporating carbon nanotubes, graphene nanoplatelets, and carbon blacks are fabricated and tested. The best performance for a specific thickness is observed for the multilayered composite with a gradual increase in the thickness and electrical conductivity of layers. The simulation results based on the proposed model are shown to be in good agreement with the experimental data. The effect of filler alignment on shielding efficiency is also studied by using the nematic order parameter. The ability of a nanocomposite to shield the incident power is found to decrease by increasing alignment especially for high volume fractions of prolate fillers. The interaction of the electromagnetic wave and the fillers is mainly affected by the polarization of the electric field; when the electric field is perpendicular to the equatorial axis of a spheroid, the interaction is significantly reduced and results in a lower shielding efficiency. Apart from the filler alignment, size polydispersity is found to have a significant effect on reflected and transmitted powers. It is demonstrated that the nanofillers with a higher aspect ratio mainly contribute to the shielding performance. The results are of interest in both shielding structures and microwave absorbing materials.

Development of an interpretive simulation tool for the proton radiography technique

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

Levy, M. C., E-mail: levymc@stanford.edu; Lawrence Livermore National Laboratory, Livermore, California 94551; Ryutov, D. D.

2015-03-15

Proton radiography is a useful diagnostic of high energy density (HED) plasmas under active theoretical and experimental development. In this paper, we describe a new simulation tool that interacts realistic laser-driven point-like proton sources with three dimensional electromagnetic fields of arbitrary strength and structure and synthesizes the associated high resolution proton radiograph. The present tool’s numerical approach captures all relevant physics effects, including effects related to the formation of caustics. Electromagnetic fields can be imported from particle-in-cell or hydrodynamic codes in a streamlined fashion, and a library of electromagnetic field “primitives” is also provided. This latter capability allows users tomore » add a primitive, modify the field strength, rotate a primitive, and so on, while quickly generating a high resolution radiograph at each step. In this way, our tool enables the user to deconstruct features in a radiograph and interpret them in connection to specific underlying electromagnetic field elements. We show an example application of the tool in connection to experimental observations of the Weibel instability in counterstreaming plasmas, using ∼10{sup 8} particles generated from a realistic laser-driven point-like proton source, imaging fields which cover volumes of ∼10 mm{sup 3}. Insights derived from this application show that the tool can support understanding of HED plasmas.« less

Full circuit calculation for electromagnetic pulse transmission in a high current facility

NASA Astrophysics Data System (ADS)

Zou, Wenkang; Guo, Fan; Chen, Lin; Song, Shengyi; Wang, Meng; Xie, Weiping; Deng, Jianjun

2014-11-01

We describe herein for the first time a full circuit model for electromagnetic pulse transmission in the Primary Test Stand (PTS)—the first TW class pulsed power driver in China. The PTS is designed to generate 8-10 MA current into a z -pinch load in nearly 90 ns rise time for inertial confinement fusion and other high energy density physics research. The PTS facility has four conical magnetic insulation transmission lines, in which electron current loss exists during the establishment of magnetic insulation. At the same time, equivalent resistance of switches and equivalent inductance of pinch changes with time. However, none of these models are included in a commercially developed circuit code so far. Therefore, in order to characterize the electromagnetic transmission process in the PTS, a full circuit model, in which switch resistance, magnetic insulation transmission line current loss and a time-dependent load can be taken into account, was developed. Circuit topology and an equivalent circuit model of the facility were introduced. Pulse transmission calculation of shot 0057 was demonstrated with the corresponding code FAST (full-circuit analysis and simulation tool) by setting controllable parameters the same as in the experiment. Preliminary full circuit simulation results for electromagnetic pulse transmission to the load are presented. Although divergences exist between calculated and experimentally obtained waveforms before the vacuum section, consistency with load current is satisfactory, especially at the rising edge.

Transperineal ultrasound-guided implantation of electromagnetic transponders in the prostatic fossa for localization and tracking during external beam radiation therapy.

PubMed

Garsa, Adam A; Verma, Vivek; Michalski, Jeff M; Gay, Hiram A

2014-01-01

To describe a transperineal ultrasound-guided technique for implantation of electromagnetic transponders into the prostatic fossa. Patients were placed in the dorsal lithotomy position, and local anesthetic was administered. On ultrasound, the bladder, urethra, vesicourethral anastomosis, rectum, and the prostatic fossa were carefully identified. Three transponders were implanted into the prostatic fossa under ultrasound guidance in a triangular configuration and implantation was verified by fluoroscopy. Patients underwent computed tomography (CT) simulation approximately 1 week later. All patients in this study were subsequently treated with intensity modulated radiation therapy (IMRT) to the prostatic fossa. From 2008 to 2012, 180 patients received transperineal implantation of electromagnetic transponders into the prostatic fossa and subsequently received IMRT. There were no cases of severe hematuria or rectal bleeding requiring intervention. There were no grade 3 or 4 toxicities. Three patients (1.7%) had a transponder missing on the subsequent CT simulation. Thirteen patients (7.3%) had transponder migration with a geometric residual that exceeded 2 mm for 3 consecutive days (5.6%) or rotation that exceeded 10 degrees for 5 consecutive days (1.7%). These patients underwent a resimulation CT scan to identify the new transponder coordinates. A transperineal technique for implantation of electromagnetic transponders into the prostatic fossa is safe and well tolerated, with no severe toxicity after implantation. There is a low rate of transponder loss or migration.

Design and Analysis of an Axisymmetric Phased Array Fed Gregorian Reflector System for Limited Scanning

DTIC Science & Technology

2016-01-22

Numerical electromagnetic simulations based on the multilevel fast multipole method (MLFMM) were used to analyze and optimize the antenna...and are not necessarily endorsed by the United States Government. numerical simulations with the multilevel fast multipole method (MLFMM...and optimized using numerical simulations conducted with the multilevel fast multipole method (MLFMM) using FEKO software (www.feko.info). The

Triboelectric-Electromagnetic Hybrid Generator for Harvesting Blue Energy

NASA Astrophysics Data System (ADS)

Shao, Huiyun; Cheng, Ping; Chen, Ruixuan; Xie, Lingjie; Sun, Na; Shen, Qingqing; Chen, Xiaoping; Zhu, Qianqian; Zhang, Yi; Liu, Yina; Wen, Zhen; Sun, Xuhui

2018-07-01

Progress has been developed in harvesting low-frequency and irregular blue energy using a triboelectric-electromagnetic hybrid generator in recent years. However, the design of the high-efficiency, mechanically durable hybrid structure is still challenging. In this study, we report a fully packaged triboelectric-electromagnetic hybrid generator (TEHG), in which magnets were utilized as the trigger to drive contact-separation-mode triboelectric nanogenerators (CS-TENGs) and coupled with copper coils to operate rotary freestanding-mode electromagnetic generators (RF-EMGs). The magnet pairs that produce attraction were used to transfer the external mechanical energy to the CS-TENGs, and packaging of the CS-TENG part was achieved to protect it from the ambient environment. Under a rotatory speed of 100 rpm, the CS-TENGs enabled the TEHG to deliver an output voltage, current, and average power of 315.8 V, 44.6 μA, and 90.7 μW, and the output of the RF-EMGs was 0.59 V, 1.78 mA, and 79.6 μW, respectively. The cylinder-like structure made the TEHG more easily driven by water flow and demonstrated to work as a practical power source to charge commercial capacitors. It can charge a 33 μF capacitor from 0 to 2.1 V in 84 s, and the stored energy in the capacitor can drive an electronic thermometer and form a self-powered water-temperature sensing system.[Figure not available: see fulltext.

Electromagnetic Navigation Bronchoscopy-directed Pleural Tattoo to Aid Surgical Resection of Peripheral Pulmonary Lesions.

PubMed

Tay, Jun H; Wallbridge, Peter D; Larobina, Marco; Russell, Prudence A; Irving, Louis B; Steinfort, Daniel P

2016-07-01

Limited (wedge) resection of pulmonary lesions is frequently performed as a diagnostic/therapeutic procedure. Some lesions may be difficult to locate thoracoscopically with conversion to open thoracotomy or incomplete resection being potential limitations to this approach. Multiple methods have been described to aid video-assisted thoracoscopic surgical (VATS) wedge resection of pulmonary nodules, including hookwire localization, percutaneous tattoo, or intraoperative ultrasound. We report on our experience using electromagnetic navigation bronchoscopic dye marking of small subpleural lesions to aid VATS wedge resection. A retrospective cohort study of consecutive patients undergoing VATS wedge resection of peripheral lesions. Preoperative bronchoscopy with electromagnetic navigation was utilized to guide a 25 G needle to within/adjacent to the target lesion with injection of 1 mL of methylene blue or indigo carmine under fluoroscopic vision. Six patients underwent bronchoscopic marking of peripheral pulmonary lesions, navigation deemed successful in all patients, with no procedural complications. Surgery was performed within 24 hours of bronchoscopic marking. Pleural staining by dye was visible thoracoscopically in all 6 lesions either adjacent to or overlying the lesion. All lesions were fully excised with wedge resection. Pathologic examination confirmed accuracy of dye staining. Electromagnetic navigation bronchoscopic dye marking of peripheral lesions is feasible, without complications commonly associated with percutaneous marking procedures. Further experience is required but early findings suggest that this method may have utility in aiding minimally invasive resection of small subpleural lesions.

SPIREs: A Finite-Difference Frequency-Domain electromagnetic solver for inhomogeneous magnetized plasma cylinders

NASA Astrophysics Data System (ADS)

Melazzi, D.; Curreli, D.; Manente, M.; Carlsson, J.; Pavarin, D.

2012-06-01

We present SPIREs (plaSma Padova Inhomogeneous Radial Electromagnetic solver), a Finite-Difference Frequency-Domain (FDFD) electromagnetic solver in one dimension for the rapid calculation of the electromagnetic fields and the deposited power of a large variety of cylindrical plasma problems. The two Maxwell wave equations have been discretized using a staggered Yee mesh along the radial direction of the cylinder, and Fourier transformed along the other two dimensions and in time. By means of this kind of discretization, we have found that mode-coupling of fast and slow branches can be fully resolved without singularity issues that flawed other well-established methods in the past. Fields are forced by an antenna placed at a given distance from the plasma. The plasma can be inhomogeneous, finite-temperature, collisional, magnetized and multi-species. Finite-temperature Maxwellian effects, comprising Landau and cyclotron damping, have been included by means of the plasma Z dispersion function. Finite Larmor radius effects have been neglected. Radial variations of the plasma parameters are taken into account, thus extending the range of applications to a large variety of inhomogeneous plasma systems. The method proved to be fast and reliable, with accuracy depending on the spatial grid size. Two physical examples are reported: fields in a forced vacuum waveguide with the antenna inside, and forced plasma oscillations in the helicon radiofrequency range.

Unified physical mechanism of frequency-domain controlled-source electromagnetic exploration on land and in ocean

NASA Astrophysics Data System (ADS)

Liu, Changsheng; Lin, Jun; Zhou, Fengdao; Hu, Ruihua; Sun, Caitang

2013-12-01

The frequency-domain controlled-source electromagnetic method (FDCSEM) has played an important role in the terrestrial and oceanic exploration. However, the measuring manners and the detecting abilities in two kinds of environment are much different. This paper analyses the electromagnetic theories of the FDCSEM exploration on land and in ocean, simulates the electromagnetic responses in the two cases based on a united physical and mathematical model, and studies the physical mechanism leading to these differences. In this study, the relationship between the propagation paths and the detecting ability is illuminated and the way to improve the detecting ability of FDCSEM is brought forward. In terrestrial exploration, FDCSEM widely adopts the measuring manner of controlled-source audio-frequency magnetotelluric method (CSAMT), which records the electromagnetic fields in the far zone in the broadside direction of an electric dipole source. This manner utilizes the airwave (i.e. the Earth surface wave) and takes the stratum wave as interference. It is sensitive to the conductive target but insensitive to the resistive one. In oceanic exploration, FDCSEM usually adopts the measuring manner of marine controlled-source electromagnetic method (MCSEM), which records the electromagnetic fields, commonly the horizontal electric fields, in the in-line direction of the electric dipole source. This manner utilizes the stratum wave (i.e. the seafloor wave and the guided wave in resistive targets) and takes the airwave as interference. It is sensitive to the resistive target but relatively insensitive to the conductive one. The numerical simulation shows that both the airwave and the stratum wave contribute to the FDCSEM exploration. United utilization of them will enhance the anomalies of targets and congregate the advantages of CSAMT and MCSEM theories. At different azimuth and different offset, the contribution of the airwave and the stratum wave to electromagnetic anomaly is different. Observation at moderate offset in the in-line direction is the best choice for the exploration of resistive targets, no matter the environment is land or shallow sea. It is also the best choice for the exploration of conductive targets in terrestrial environment. As for the conductive targets in shallow sea, observation at moderate offset in the broadside direction is better. Synthetic and felicitous utilization of the airwave and the stratum wave will optimize the performance of FDCSEM.

Electromagnetic methods for mapping freshwater lenses on Micronesian atoll islands

USGS Publications Warehouse

Anthony, S.S.

1992-01-01

The overall shape of freshwater lenses can be determined by applying electromagnetic methods and inverse layered-earth modeling to the mapping of atoll island freshwater lenses. Conductivity profiles were run across the width of the inhabited islands at Mwoakilloa, Pingelap, and Sapwuahfik atolls of the Pohnpei State, Federated States of Micronesia using a dual-loop, frequency-domain, electromagnetic profiling system. Six values of apparent conductivity were recorded at each sounding station and were used to interpret layer conductivities and/or thicknesses. A three-layer model that includes the unsaturated, freshwater, and saltwater zones was used to simulate apparent-conductivity data measured in the field. Interpreted results were compared with chloride-concentration data from monitoring wells and indicate that the interface between freshwater and saltwater layers, defined from electromagnetic data, is located in the upper part of the transition zone, where the chloride-concentration profile shows a rapid increase with depth. The electromagnetic method can be used to interpret the thickness of the freshwater between monitoring wells, but can not be used to interpret the thickness of freshwater from monitoring wells to the margin of an island. ?? 1992.

Sliding mode control of electromagnetic tethered satellite formation

NASA Astrophysics Data System (ADS)

Hallaj, Mohammad Amin Alandi; Assadian, Nima

2016-08-01

This paper investigates the control of tethered satellite formation actuated by electromagnetic dipoles and reaction wheels using the robust sliding mode control technique. Generating electromagnetic forces and moments by electric current coils provides an attractive control actuation alternative for tethered satellite system due to the advantages of no propellant consumption and no obligatory rotational motion. Based on a dumbbell model of tethered satellite in which the flexibility and mass of the tether is neglected, the equations of motion in Cartesian coordinate are derived. In this model, the J2 perturbation is taken into account. The far-field and mid-field models of electromagnetic forces and moments of two satellites on each other and the effect of the Earth's magnetic field are presented. A robust sliding mode controller is designed for precise trajectory tracking purposes and to deal with the electromagnetic force and moment uncertainties and external disturbances due to the Earth's gravitational and magnetic fields inaccuracy. Numerical simulation results are presented to validate the effectiveness of the developed controller and its superiority over the linear controller.

Electromagnetic diffraction radiation of a subwavelength-hole array excited by an electron beam.

PubMed

Liu, Shenggang; Hu, Min; Zhang, Yaxin; Li, Yuebao; Zhong, Renbin

2009-09-01

This paper explores the physics of the electromagnetic diffraction radiation of a subwavelength holes array excited by a set of evanescent waves generated by a line charge of electron beam moving parallel to the array. Activated by a uniformly moving line charge, numerous physical phenomena occur such as the diffraction radiation on both sides of the array as well as the electromagnetic penetration or transmission below or above the cut-off through the holes. As a result the subwavelength holes array becomes a radiation array. Making use of the integral equation with relevant Green's functions, an analytical theory for such a radiation system is built up. The results of the numerical calculations based on the theory agree well with that obtained by the computer simulation. The relation among the effective surface plasmon wave, the electromagnetic penetration or transmission of the holes and the diffraction radiation is revealed. The energy dependence of and the influence of the hole thickness on the diffraction radiation and the electromagnetic penetration or transmission are investigated in detail. Therefore, a distinct diffraction radiation phenomenon is discovered.

An ODE-Based Wall Model for Turbulent Flow Simulations

NASA Technical Reports Server (NTRS)

Berger, Marsha J.; Aftosmis, Michael J.

2017-01-01

Fully automated meshing for Reynolds-Averaged Navier-Stokes Simulations, Mesh generation for complex geometry continues to be the biggest bottleneck in the RANS simulation process; Fully automated Cartesian methods routinely used for inviscid simulations about arbitrarily complex geometry; These methods lack of an obvious & robust way to achieve near wall anisotropy; Goal: Extend these methods for RANS simulation without sacrificing automation, at an affordable cost; Note: Nothing here is limited to Cartesian methods, and much becomes simpler in a body-fitted setting.

Back to basics: history of photonic crystals and metamaterials

NASA Astrophysics Data System (ADS)

Soukoulis, Costas M.

2018-04-01

We will review the history of photonic crystals and overview of the theoretical and experimental efforts in obtaining a photonic bandgap, a frequency band in three-dimensional dielectric structures in which electromagnetic (EM) waves are forbidden, is presented. Many experimental groups all over the world still employ this woodpile structure to fabricate PCs at optical wavelengths, waveguides, enhance nanocavities, and produce nanolasers with a low threshold limit. We have been focused on a new class of materials, the so-called metamaterials (MMs) or negative-index materials, which exhibit highly unusual electromagnetic properties and hold promise for new device applications. Metamaterials can be designed to exhibit both electric and magnetic resonances that can be separately tuned to occur in frequency bands from megahertz to terahertz frequencies, and hope-fully to the visible region of the EM spectrum.

Space shuttle electromagnetic environment experiment. Phase A: Definition study

NASA Technical Reports Server (NTRS)

Haber, F.; Showers, R. M.; Taheri, S. H.; Forrest, L. A., Jr.; Kocher, C.

1974-01-01

A program is discussed which develops a concept for measuring the electromagnetic environment on earth with equipment on board an orbiting space shuttle. Earlier work on spaceborne measuring experiments is reviewed, and emissions to be expected are estimated using, in part, previously gathered data. General relations among system parameters are presented, followed by a proposal on spatial and frequency scanning concepts. The methods proposed include a nadir looking measurement with small lateral scan and a circularly scanned measurement looking tangent to the earth's surface at the horizon. Antenna requirements are given, assuming frequency coverage from 400 MHz to 40 GHz. For the low frequency range, 400-1000 MHz, a processed, thinned array is proposed which will be more fully analyzed in the next phase of the program. Preliminary hardware and data processing requirements are presented.

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.

Radio Frequency Mass Gauging of Propellants

NASA Technical Reports Server (NTRS)

Zimmerli, Gregory A.; Vaden, Karl R.; Herlacher, Michael D.; Buchanan, David A.; VanDresar, Neil T.

2007-01-01

A combined experimental and computer simulation effort was conducted to measure radio frequency (RF) tank resonance modes in a dewar partially filled with liquid oxygen, and compare the measurements with numerical simulations. The goal of the effort was to demonstrate that computer simulations of a tank's electromagnetic eigenmodes can be used to accurately predict ground-based measurements, thereby providing a computational tool for predicting tank modes in a low-gravity environment. Matching the measured resonant frequencies of several tank modes with computer simulations can be used to gauge the amount of liquid in a tank, thus providing a possible method to gauge cryogenic propellant tanks in low-gravity. Using a handheld RF spectrum analyzer and a small antenna in a 46 liter capacity dewar for experimental measurements, we have verified that the four lowest transverse magnetic eigenmodes can be accurately predicted as a function of liquid oxygen fill level using computer simulations. The input to the computer simulations consisted of tank dimensions, and the dielectric constant of the fluid. Without using any adjustable parameters, the calculated and measured frequencies agree such that the liquid oxygen fill level was gauged to within 2 percent full scale uncertainty. These results demonstrate the utility of using electromagnetic simulations to form the basis of an RF mass gauging technology with the power to simulate tank resonance frequencies from arbitrary fluid configurations.

Design and Simulation of Horn Antenna Using CST Software for GPR System

NASA Astrophysics Data System (ADS)

Joret, Ariffuddin; Sulong, M. S.; Abdullah, M. F. L.; Madun, Aziman; Haimi Dahlan, Samsul

2018-04-01

Detection of underground object can be made using a GPR system. This system is classified as a non-destructive technique (NDT) where the ground areas need not to be excavated. The technique used by the GPR system is by measuring the reflection of electromagnetic wave signal produced and detected by antenna which is known as the transmitter and the receiver antenna. In this study, a GPR system was studied by means of simulation using a Horn antenna as a transceiver antenna. The electromagnetic wave signal in this simulation is produced by current signal of an antenna which having a shape of modulation of Gaussian pulse which is having spectrum from 8 GHz until 12 GHz. CST and MATLAB Software are used in this GPR system simulation. A model of a Horn antenna has been designed using the CST software before the GPR’s system simulation modeled by adding a model of background in front of the Horn antenna. The simulation results show that the output signal of the Horn antenna can be used in detecting embedded object which are made from material of wood and iron. In addition, the simulation result has successfully developed a 3D model image of the GPR system using output signal of the Horn antenna. The embedded iron object in the GPR system simulation can be seen clearly by using this 3D image.

Strong field QED in lepton colliders and electron/laser interactions

NASA Astrophysics Data System (ADS)

Hartin, Anthony

2018-05-01

The studies of strong field particle physics processes in electron/laser interactions and lepton collider interaction points (IPs) are reviewed. These processes are defined by the high intensity of the electromagnetic fields involved and the need to take them into account as fully as possible. Thus, the main theoretical framework considered is the Furry interaction picture within intense field quantum field theory. In this framework, the influence of a background electromagnetic field in the Lagrangian is calculated nonperturbatively, involving exact solutions for quantized charged particles in the background field. These “dressed” particles go on to interact perturbatively with other particles, enabling the background field to play both macroscopic and microscopic roles. Macroscopically, the background field starts to polarize the vacuum, in effect rendering it a dispersive medium. Particles encountering this dispersive vacuum obtain a lifetime, either radiating or decaying into pair particles at a rate dependent on the intensity of the background field. In fact, the intensity of the background field enters into the coupling constant of the strong field quantum electrodynamic Lagrangian, influencing all particle processes. A number of new phenomena occur. Particles gain an intensity-dependent rest mass shift that accounts for their presence in the dispersive vacuum. Multi-photon events involving more than one external field photon occur at each vertex. Higher order processes which exchange a virtual strong field particle resonate via the lifetimes of the unstable strong field states. Two main arenas of strong field physics are reviewed; those occurring in relativistic electron interactions with intense laser beams, and those occurring in the beam-beam physics at the interaction point of colliders. This review outlines the theory, describes its significant novel phenomenology and details the experimental schema required to detect strong field effects and the simulation programs required to model them.

Laser-Induced Translative Hydrodynamic Mass Snapshots: Noninvasive Characterization and Predictive Modeling via Mapping at Nanoscale

NASA Astrophysics Data System (ADS)

Wang, X. W.; Kuchmizhak, A. A.; Li, X.; Juodkazis, S.; Vitrik, O. B.; Kulchin, Yu. N.; Zhakhovsky, V. V.; Danilov, P. A.; Ionin, A. A.; Kudryashov, S. I.; Rudenko, A. A.; Inogamov, N. A.

2017-10-01

Subwavelength structures (meta-atoms) with artificially engineered permittivity and permeability have shown promising applications for guiding and controlling the flow of electromagnetic energy on the nanoscale. Ultrafast laser nanoprinting emerges as a promising single-step, green and flexible technology in fabricating large-area arrays of meta-atoms through the translative or ablative modification of noble-metal thin films. Ultrafast laser energy deposition in noble-metal films produces irreversible, intricate nanoscale translative mass redistributions after resolidification of the transient thermally assisted hydrodynamic melt perturbations. Such mass redistribution results in the formation of a radially symmetric frozen surface with modified hidden nanofeatures, which strongly affect the optical response harnessed in plasmonic sensing and nonlinear optical applications. Here, we demonstrate that side-view electron microscopy and ion-beam cross sections together with low-energy electron x-ray dispersion microscopy provide exact information about such three-dimensional patterns, enabling an accurate acquisition of their cross-sectional mass distributions. Such nanoscale solidified structures are theoretically modeled, considering the underlying physical processes associated with laser-induced energy absorption, electron-ion energy exchange, acoustic relaxation, and hydrodynamic flows. A theoretical approach, separating slow and fast physical processes and combining hybrid analytical two-temperature calculations, scalable molecular-dynamics simulations, and a semianalytical thin-shell model is synergistically applied. These advanced characterization approaches are required for a detailed modeling of near-field electromagnetic response and pave the way to a fully automated noninvasive in-line control of a high-throughput and large-scale laser fabrication. This theoretical modeling provides an accurate prediction of scales and topographies of the laser-fabricated meta-atoms and metasurfaces.

Harvesting Broad Frequency Band Blue Energy by a Triboelectric-Electromagnetic Hybrid Nanogenerator.

PubMed

Wen, Zhen; Guo, Hengyu; Zi, Yunlong; Yeh, Min-Hsin; Wang, Xin; Deng, Jianan; Wang, Jie; Li, Shengming; Hu, Chenguo; Zhu, Liping; Wang, Zhong Lin

2016-07-26

Ocean wave associated energy is huge, but it has little use toward world energy. Although such blue energy is capable of meeting all of our energy needs, there is no effective way to harvest it due to its low frequency and irregular amplitude, which may restrict the application of traditional power generators. In this work, we report a hybrid nanogenerator that consists of a spiral-interdigitated-electrode triboelectric nanogenerator (S-TENG) and a wrap-around electromagnetic generator (W-EMG) for harvesting ocean energy. In this design, the S-TENG can be fully isolated from the external environment through packaging and indirectly driven by the noncontact attractive forces between pairs of magnets, and W-EMG can be easily hybridized. Notably, the hybrid nanogenerator could generate electricity under either rotation mode or fluctuation mode to collect energy in ocean tide, current, and wave energy due to the unique structural design. In addition, the characteristics and advantages of outputs indicate that the S-TENG is irreplaceable for harvesting low rotation speeds (<100 rpm) or motion frequencies (<2 Hz) energy, which fits the frequency range for most of the water wave based blue energy, while W-EMG is able to produce larger output at high frequencies (>10 Hz). The complementary output can be maximized and hybridized for harvesting energy in a broad frequency range. Finally, a single hybrid nanogenerator unit was demonstrated to harvest blue energy as a practical power source to drive several LEDs under different simulated water wave conditions. We also proposed a blue energy harvesting system floating on the ocean surface that could simultaneously harvest wind, solar, and wave energy. The proposed hybrid nanogenerator renders an effective and sustainable progress in practical applications of the hybrid nanogenerator toward harvesting water wave energy offered by nature.

Electromagnetic Scattering by Fully Ordered and Quasi-Random Rigid Particulate Samples

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Dlugach, Janna M.; Mackowski, Daniel W.

2016-01-01

In this paper we have analyzed circumstances under which a rigid particulate sample can behave optically as a true discrete random medium consisting of particles randomly moving relative to each other during measurement. To this end, we applied the numerically exact superposition T-matrix method to model far-field scattering characteristics of fully ordered and quasi-randomly arranged rigid multiparticle groups in fixed and random orientations. We have shown that, in and of itself, averaging optical observables over movements of a rigid sample as a whole is insufficient unless it is combined with a quasi-random arrangement of the constituent particles in the sample. Otherwise, certain scattering effects typical of discrete random media (including some manifestations of coherent backscattering) may not be accurately replicated.

CaloGAN: Simulating 3D high energy particle showers in multilayer electromagnetic calorimeters with generative adversarial networks

NASA Astrophysics Data System (ADS)

Paganini, Michela; de Oliveira, Luke; Nachman, Benjamin

2018-01-01

The precise modeling of subatomic particle interactions and propagation through matter is paramount for the advancement of nuclear and particle physics searches and precision measurements. The most computationally expensive step in the simulation pipeline of a typical experiment at the Large Hadron Collider (LHC) is the detailed modeling of the full complexity of physics processes that govern the motion and evolution of particle showers inside calorimeters. We introduce CaloGAN, a new fast simulation technique based on generative adversarial networks (GANs). We apply these neural networks to the modeling of electromagnetic showers in a longitudinally segmented calorimeter and achieve speedup factors comparable to or better than existing full simulation techniques on CPU (100 ×-1000 × ) and even faster on GPU (up to ˜105× ). There are still challenges for achieving precision across the entire phase space, but our solution can reproduce a variety of geometric shower shape properties of photons, positrons, and charged pions. This represents a significant stepping stone toward a full neural network-based detector simulation that could save significant computing time and enable many analyses now and in the future.

Simulation of electromagnetic ion cyclotron triggered emissions in the Earth's inner magnetosphere

NASA Astrophysics Data System (ADS)

Shoji, Masafumi; Omura, Yoshiharu

2011-05-01

In a recent observation by the Cluster spacecraft, emissions triggered by electromagnetic ion cyclotron (EMIC) waves were discovered in the inner magnetosphere. We perform hybrid simulations to reproduce the EMIC triggered emissions. We develop a self-consistent one-dimensional hybrid code with a cylindrical geometry of the background magnetic field. We assume a parabolic magnetic field to model the dipole magnetic field in the equatorial region of the inner magnetosphere. Triggering EMIC waves are driven by a left-handed polarized external current assumed at the magnetic equator in the simulation model. Cold proton, helium, and oxygen ions, which form branches of the dispersion relation of the EMIC waves, are uniformly distributed in the simulation space. Energetic protons with a loss cone distribution function are also assumed as resonant particles. We reproduce rising tone emissions in the simulation space, finding a good agreement with the nonlinear wave growth theory. In the energetic proton velocity distribution we find formation of a proton hole, which is assumed in the nonlinear wave growth theory. A substantial amount of the energetic protons are scattered into the loss cone, while some of the resonant protons are accelerated to higher pitch angles, forming a pancake velocity distribution.