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Results for “ELECTROMAGNETIC FIELD”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

On electromagnetic field problems in inhomogeneous media

Analysis of electromagnetic fields in inhomogeneous media is of practical interest in general scattering and propagation problems and in the study of lenses. For certain types of inhomogeneities, the fields may be represented in terms of two scalars. In a general orthogonal coordinate system, these potentials satisfy second order differential equations. Exact solutions of these equations are known only for a few particular cases and in general, an approximate or numerical technique must be employed. The present work reviews and generalizes some of the main methods of attack of the problem. The results are presented in a form appropriate for numerical computation.

Mohsen, A.↗
NASA NTRS1996

Quantization of Electromagnetic Fields in Cavities

A quantization procedure for the electromagnetic field in a rectangular cavity with perfect conductor walls is presented, where a decomposition formula of the field plays an essential role. All vector mode functions are obtained by using the decomposition. After expanding the field in terms of the vector mode functions, we get the quantized electromagnetic Hamiltonian.

Kakazu, Kiyotaka↗
DOE OSTI2019

Influence of the electromagnetic field on the transition of a two-level system in a Gaussian confinement potential with LO phonon and of thickness effects

In this paper, the asymmetric Gaussian confinement potential and the parabolic confinement potential (PCP) are selected to describe the along growth direction and perpendicular to growth direction confinement potential (PC) of electron in a disk quantum dot, respectively. The phonons mean number and the energies of the ground and first excited states of the electron in a quantum dot with the polarization and the thickness effect are investigated by using Lee–Low–Pines unitary transformation and the Pekar-type variational method, and on the basis of the Fermi Golden Rule, the transition of the electron caused by the electromagnetic field is discussed. Our numerical results have displayed that the electric field and the magnetic field are an indispensable condition for the induced polaron transition. The weak electric field has a strong regulatory function on the transition. The influence of the well width L and the well depth V{sub 0} of the AGFCP on the mean number of phonons, energies and transition are important and interesting; it is also found in this work that the AGFCP is better than PCP in explaining the quantum size effect of QDs and modulating electron transition properties, respectively. This quantum system can be employed as a two-level quantum qubit.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Testing the impact of electromagnetic fields on the directed flow of constituent quarks in heavy-ion collisions

It has been proposed that strong electromagnetic fields produced in the early stages of heavy-ion collisions can lead to splitting of the rapidity-odd directed flow of positive and negative hadrons. For light hadrons, the interpretation of such measurements is complicated by the low magnitude of directed flow as well as by ambiguities arising from transported quarks. To overcome these complications, we propose measurements using only hadrons carrying produced quarks (u¯, d¯, s s¯ ). Here, we discuss how to identify the kinematics where such hadrons are produced via the coalescence mechanism and therefore their flow is the sum of the flow of their constituent quarks. With this sum rule verified for certain combinations of hadrons, the expected systematic violation of this rule with increasing electric charge can be measured, which could be a consequence of the electromagnetic fields produced in the collisions. Our approach can be tested with the high statistics data from Phase II of the Beam Energy Scan program at the Relativistic Heavy Ion Collider.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1994

High-order squeezing of the quantum electromagnetic field and the generalized uncertainty relations in two-mode squeezed states

It is found that two-mode output quantum electromagnetic field in two-mode squeezed states exhibits higher-order squeezing to all even orders. And the generalized uncertainty relations are also presented for the first time. The concept of higher-order squeezing of the single-mode quantum electromagnetic field was first introduced and applied to several processes by Hong and Mandel in 1985. Lately Li Xizeng and Shan Ying have calculated the higher-order squeezing in the process of degenerate four-wave mixing and presented the higher-order uncertainty relations of the fields in single-mode squeezed states. In this paper we generalize the above work to the higher-order squeezing in two-mode squeezed states. The generalized uncertainty relations are also presented for the first time.

Li, Xi-Zeng↗
DOE OSTI2021

Mapping the electromagnetic fields of heavy-ion collisions with the Breit-Wheeler process

Ultra-relativistic heavy-ion collisions are expected to produce the strongest electromagnetic fields in the known Universe. These highly-Lorentz contracted fields can manifest themselves as linearly polarized quasi-real photons that can interact via the Breit-Wheeler process to produce lepton anti-lepton pairs. Furthermore, the energy and momentum distribution of the produced dileptons carry information about the strength and spatial distribution of the colliding fields. Recently it has been demonstrated that photons from these fields can interact even in heavy-ion collisions with hadronic overlap, providing a purely electromagnetic probe of the produced medium. In this review we discuss the recent theoretical progress and experimental advances for mapping the ultra-strong electromagnetic fields produced in heavy-ion collisions via measurement of the Breit-Wheeler process.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Association between media coverage and prevalence of idiopathic environmental intolerance attributed to electromagnetic field in Taiwan

Highlights: • The prevalence rate of IEI-EMF in Taiwan declined form 13.3% in 2007 to 4.6% in 2012. • Residents in Taiwan had increasing exposure to EMF related to mobile phone use during the same period of time. • Media coverage of EMF related issues had the similar trend with the decreased IEI-EMF prevalence rate. • Most media coverage conveyed information on the negative health impacts of EMF. • Risk communications seem to be more effective than precautionary measures in coping with the public fears about EMF. Idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) describes symptoms sufferers attribute to exposure to electromagnetic fields (EMF). In Taiwan, the prevalence rate of IEI-EMF was 13.3% in 2007, but a survey using the same method found the rate declined to 4.6% in 2012. Because media reports may encourage readers to attribute their symptoms to EMF, the change might be related to media coverage. We searched articles indexed in the largest newspaper database in Taiwan to evaluate the association between media coverage and the prevalence of IEI-EMF. We also assessed the effects of other potential affecting factors. The number of newspaper articles related to EMF and IEI-EMF increased from 2005 to 2007 and then has been decreasing until 2012, which is compatible with the change in the prevalence of IEI-EMF. However, from 2007 to 2012, the other potential affecting factors such as density of mobile phone base stations, number of mobile phone users, total mobile phone calling time, and number of text messages sent through mobile phones all increased in Taiwan. This finding indicated a positive association between media coverage and the prevalence of IEI-EMF in Taiwan, which might also be true in other countries.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗
NASA NTRS1978

Electromagnetic fields radiated from a lightning return stroke - Application of an exact solution to Maxwell's equations

A solution is presented for the electromagnetic fields radiated by an arbitrarily oriented current filament over a conducting ground plane in the case where the current propagates along the filament at the speed of light, and this solution is interpreted in terms of radiation from lightning return strokes. The solution is exact in the fullest sense; no mathematical approximations are made, and the governing differential equations and boundary conditions are satisfied. The solution has the additional attribute of being specified in closed form in terms of elementary functions. This solution is discussed from the point of view of deducing lightning current wave forms from measurements of the electromagnetic fields and understanding the effects of channel tortuosity on the radiated fields. In addition, it is compared with two approximate solutions, the traditional moment approximation and the Fraunhofer approximation, and a set of criteria describing their applicability are presented and interpreted.

D M Le Vine↗
NASA NTRS2003

Physiological and Molecular Genetic Effects of Time-Varying Electromagnetic Fields on Human Neuronal Cells

The present investigation details the development of model systems for growing two- and three-dimensional human neural progenitor cells within a culture medium facilitated by a time-varying electromagnetic field (TVEMF). The cells and culture medium are contained within a two- or three-dimensional culture vessel, and the electromagnetic field is emitted from an electrode or coil. These studies further provide methods to promote neural tissue regeneration by means of culturing the neural cells in either configuration. Grown in two dimensions, neuronal cells extended longitudinally, forming tissue strands extending axially along and within electrodes comprising electrically conductive channels or guides through which a time-varying electrical current was conducted. In the three-dimensional aspect, exposure to TVEMF resulted in the development of three-dimensional aggregates, which emulated organized neural tissues. In both experimental configurations, the proliferation rate of the TVEMF cells was 2.5 to 4.0 times the rate of the non-waveform cells. Each of the experimental embodiments resulted in similar molecular genetic changes regarding the growth potential of the tissues as measured by gene chip analyses, which measured more than 10,000 human genes simultaneously.

Goodwin, Thomas J.↗
DOE OSTI2023

Exact solutions for the electromagnetic fields of a flying focus

The intensity peak of a “flying” focus travels at a programmable velocity over many Rayleigh ranges while maintaining a near-constant profile. Assessing the extent to which these features can enhance laser-based applications requires an accurate description of the electromagnetic fields. Here we present exact analytical solutions to Maxwell’s equations for the electromagnetic fields of a constant-velocity flying focus, generalized for arbitrary polarization and orbital angular momentum. Furthermore, the approach combines the complex source-point method, which transforms multipole solutions into beam-like solutions, with the Lorentz invariance of Maxwell’s equations. Propagating the fields backward in space reveals the space-time profile that an optical assembly must produce to realize these fields in the laboratory. Comparisons with simpler paraxial solutions provide conditions for their reliable use when modeling a flying focus.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Impact of Electromagnetic Fields on Gypsum and Silica Scaling in Reverse Osmosis

Electromagnetic field (EMF) is a cost-effective, simple, and energy-efficient method for scale control in reverse osmosis (RO) systems. However, its effects on gypsum and silica scaling, as well as the underlying mechanisms, remain poorly understood. This study systematically investigates the effects of EMF treatment on gypsum and silica scaling in RO systems, utilizing synthetic brackish water and natural RO concentrate (ROC) from a desalination facility. For gypsum, EMF changes the crystal morphology, resulting in the formation of a porous, less compact scaling layer. It is more readily removed through hydraulic flushing (HF), enhancing scaling reversibility and water recovery. In the case of silica scaling, EMF promotes homogeneous polymerization in the bulk solution, producing larger silica particles that inhibit the formation of a dense, cross-linked gel layer on the membrane surface, mitigating flux decline. This study thus demonstrates EMF’s effectiveness in controlling gypsum scaling in undersaturated feedwaters when combined with HF and in mitigating silica scaling under both HF and non-HF conditions for supersaturated feedwaters. These findings underscore EMF’s versatility as a nonchemical approach for scale control in RO desalination and show its substantial potential to enhance membrane performance and operational efficiency in real-world water treatment applications.

Du, Xuewei [New Mexico State University, Las Cruce↗
DOE OSTI2019

In-Vehicle Assessment of Human Exposure to Electromagnetic Fields from 25-kW Wireless Power Transfer System Based on Near-Field Analysis

Wireless power transfer (WPT) technology has the potential to be a convenient and reliable charging method for the light and heavy duty electric vehicles. However, the loose coupling between the two sides results in strong near-electromagnetic fields (EMFs) around the system, which may have the possibility to impact human safety if the standard limits are exceeded. Therefore, comprehensive tests are necessary to ensure the electromagnetic fields are with in safe limits. This paper presents a test methodology for the near-field from a 25-kW WPT system from Momentum Dynamics, which is installed in a heavy-duty electric shuttle at the National Renewable Energy Laboratory (NREL). The paper describes in detail the measuring device, test setup, and conditions.

30 DIRECT ENERGY CONVERSION↗