Science.gov

Sample records for electromagnetism

  1. ELECTROMAGNETIC PUMP

    DOEpatents

    Pulley, O.O.

    1954-08-17

    This patent reiates to electromagnetic pumps for electricity-conducting fluids and, in particular, describes several modifications for a linear conduction type electromagnetic interaction pump. The invention resides in passing the return conductor for the current traversing the fiuid in the duct back through the gap in the iron circuit of the pump. Both the maximum allowable pressure and the efficiency of a linear conduction electromagnetic pump are increased by incorporation of the present invention.

  2. Electromagnetic Attraction.

    ERIC Educational Resources Information Center

    Milson, James L.

    1990-01-01

    Three activities involving electromagnetism are presented. Discussed are investigations involving the construction of an electromagnet, the effect of the number of turns of wire in the magnet, and the effect of the number of batteries in the circuit. Extension activities are suggested. (CW)

  3. Electromagnetic fasteners

    DOEpatents

    Crane, Randolph W.; Marts, Donna J.

    1994-11-01

    An electromagnetic fastener for manipulating objects in space uses the matic attraction of various metals. An end effector is attached to a robotic manipulating system having an electromagnet such that when current is supplied to the electromagnet, the object is drawn and affixed to the end effector, and when the current is withheld, the object is released. The object to be manipulated includes a multiplicity of ferromagnetic patches at various locations to provide multiple areas for the effector on the manipulator to become affixed to the object. The ferromagnetic patches are sized relative to the object's geometry and mass.

  4. Electromagnetic fasteners

    DOEpatents

    Crane, Randolph W.; Marts, Donna J.

    1994-01-01

    An electromagnetic fastener for manipulating objects in space uses the matic attraction of various metals. An end effector is attached to a robotic manipulating system having an electromagnet such that when current is supplied to the electromagnet, the object is drawn and affixed to the end effector, and when the current is withheld, the object is released. The object to be manipulated includes a multiplicity of ferromagnetic patches at various locations to provide multiple areas for the effector on the manipulator to become affixed to the object. The ferromagnetic patches are sized relative to the object's geometry and mass.

  5. Electromagnetic Accelerator

    NASA Astrophysics Data System (ADS)

    Land, Jared

    2012-03-01

    The objective of this senior physics student research project was to design a functional electromagnetic accelerator (i.e. railgun), with considerations for size, portability, modularity, and weight. This has been accomplished through practical design application of electromagnetic principles and streamlined construction to study effects of various rail geometries/bore profiles, and projectile design. The railgun has been tested and its efficiency has been studied.

  6. Electromagnetic Propulsion

    NASA Technical Reports Server (NTRS)

    Schafer, Charles

    2000-01-01

    The design and development of an Electromagnetic Propulsion is discussed. Specific Electromagnetic Propulsion Topics discussed include: (1) Technology for Pulse Inductive Thruster (PIT), to design, develop, and test of a multirepetition rate pulsed inductive thruster, Solid-State Switch Technology, and Pulse Driver Network and Architecture; (2) Flight Weight Magnet Survey, to determine/develop light weight high performance magnetic materials for potential application Advanced Space Flight Systems as these systems develop; and (3) Magnetic Flux Compression, to enable rapid/robust/reliable omni-planetary space transportation within realistic development and operational costs constraints.

  7. Electromagnetic Survey

    USGS hydrologist conducts a broadband electromagnetic survey in New Orleans, Louisiana. The survey was one of several geophysical methods used during USGS applied research on the utility of the multi-channel analysis of surface waves (MASW) seismic method for non-invasive assessment of earthen levee...

  8. Electromagnetic Survey

    A USGS hydrologist conducts a near-surface electromagnetic induction survey to characterize the shallow earth. The survey was conducted as part of an applied research effort by the USGS Office of Groundwater Branch of Geophysics at Camp Rell, Connecticut, in 2008....

  9. Electromagnetic Reciprocity.

    SciTech Connect

    Aldridge, David F.

    2014-11-01

    A reciprocity theorem is an explicit mathematical relationship between two different wavefields that can exist within the same space - time configuration. Reciprocity theorems provi de the theoretical underpinning for mod ern full waveform inversion solutions, and also suggest practical strategies for speed ing up large - scale numerical modeling of geophysical datasets . In the present work, several previously - developed electromagnetic r eciprocity theorems are generalized to accommodate a broader range of medi um, source , and receiver types. Reciprocity relations enabling the interchange of various types of point sources and point receivers within a three - dimensional electromagnetic model are derived. Two numerical modeling algorithms in current use are successfully tested for adherence to reciprocity. Finally, the reciprocity theorem forms the point of departure for a lengthy derivation of electromagnetic Frechet derivatives. These mathe matical objects quantify the sensitivity of geophysical electromagnetic data to variatio ns in medium parameters, and thus constitute indispensable tools for solution of the full waveform inverse problem. ACKNOWLEDGEMENTS Sandia National Labor atories is a multi - program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE - AC04 - 94AL85000. Signif icant portions of the work reported herein were conducted under a Cooperative Research and Development Agreement (CRADA) between Sandia National Laboratories (SNL) and CARBO Ceramics Incorporated. The author acknowledges Mr. Chad Cannan and Mr. Terry Pa lisch of CARBO Ceramics, and Ms. Amy Halloran, manager of SNL's Geophysics and Atmospheric Sciences Department, for their interest in and encouragement of this work. Special thanks are due to Dr . Lewis C. Bartel ( recently retired from Sandia National Labo ratories and now a geophysical consultant ) and Dr. Chester J. Weiss (recently rejoined with Sandia National Laboratories) for many stimulating (and reciprocal!) discussions regar ding the topic at hand.

  10. Electromagnetic microactuators

    NASA Astrophysics Data System (ADS)

    Büttgenbach, S.; Al-Halhouli, A. T.; Feldmann, M.; Seidemann, V.; Waldschik, A.

    2013-05-01

    High precision microactuators have become key elements for many applications of MEMS, for example for positioning and handling systems as well as for microfluidic devices. Electromagnetic microactuators exhibit considerable benefits such as high forces, large deflections, low input impedances and thus, the involvement of only low voltages. Most of the magnetic microactuators developed so far are based on the variable reluctance principle and use soft magnetic materials. Since the driving force of such actuators is proportional to their volume, they require structures with rather great heights and aspect ratios. Therefore, the development of new photo resists, which allow UV exposure of thick layers of resist, has been essential for the advancement of variable reluctance microactuators. On the other hand, hard magnetic materials have the potential for larger forces and larger deflections. Accordingly, polymer magnets, in which micro particles of hard magnetic material are suspended in a polymer matrix, have been used to fabricate permanent magnet microactuators. In this paper we give an overview of sophisticated electromagnetic microactuators which have been developed in our laboratory in the framework of the Collaborative Research Center "Design and Manufacturing of Active Microsystems". In particular, concept, fabrication and test of variable reluctance micro stepper motors, of permanent magnet synchronous micromotors and of microactuators based on the Lorentz force principle will be described. Special emphasis will be given to applications in lab-on-chip systems.

  11. Electromagnetic Gravitation

    NASA Astrophysics Data System (ADS)

    Montgomery, Jerry; Russell, Philmore

    2005-03-01

    Recent analysis of radio metric data from several space probes deployed by NASA indicate that they are being slowed by an anomalous constant acceleration with an average magnitude of 8x10-10m/s^2 oriented with respect to the sun. Analysis of their slowdown, in addition to many other anomalous astrophysical phenomena indicates that a negative curvature of the space-time continuum is produced by the electromagnetic radiation of the sun. The acceleration appears to have a close relation to the wavelength λat which the sun radiates most intensely. The evidence that supports our hypothesis may also provide solutions to the flat rotation curve of the galaxy, and rogue stars and planets within the galaxy. Calculations using the data concerning the four probes result in the formula -a=c^2λ which expresses a negative acceleration that is proportional to the speed of light divided by the peak wavelength, multiplied by a new constant k. The evidence also gives a strong indication that light, in addition to its particle-wave nature, produces gravitational field-like characteristics through interacting with the space-time continuum.

  12. Electromagnetic gravitation

    NASA Astrophysics Data System (ADS)

    Montgomery, Jerry, , Dr.

    2005-04-01

    Recent analysis of radio metric data from several space probes deployed by NASA indicate that they are being slowed by an anomalous constant acceleration with an average magnitude of 8x10-10m/s^2 oriented with respect to the sun. Analysis of their slowdown, in addition to many other anomalous astrophysical phenomena indicates that a negative curvature of the space-time continuum is produced by the electromagnetic radiation of the sun. The acceleration appears to have a close relation to the wavelength λat which the sun radiates most intensely. The evidence that supports our hypothesis may also provide solutions to the flat rotation curve of the galaxy, and rogue stars and planets within the galaxy. Calculations using the data concerning the four probes result in the formula -a=c^2λ which expresses a negative acceleration that is proportional to the speed of light divided by the peak wavelength, multiplied by a new constant k. The evidence also gives a strong indication that light, in addition to its particle-wave nature, produces gravitational field-like characteristics through interacting with the space-time continuum.

  13. Electromagnetic induction methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electromagnetic induction geophysical methods are finding greater and greater use for agricultural purposes. Electromagnetic induction methods measure the electrical conductivity (or resistivity) for a bulk volume of soil directly beneath the surface. An instrument called a ground conductivity meter...

  14. Principles of electromagnetic theory

    SciTech Connect

    Kovetz, A.H. )

    1990-01-01

    This book emphasizes the fundamental understanding of the laws governing the behavior of charge and current carrying bodies. Electromagnetism is presented as a classical theory, based-like mechanics-on principles that are independent of the atomic constitution of matter. This book is unique among electromagnetic texts in its treatment of the precise manner in which electromagnetism is linked to mechanics and thermodynamics. Applications include electrostriction, piezoelectricity, ferromagnetism, superconductivity, thermoelectricity, magnetohydrodynamics, radiation from charged particles, electromagnetic wave propagation and guided waves. There are many worked examples of dynamical and thermal effects of electromagnetic fields, and of effects resulting from the motion of bodies.

  15. Electromagnetic structure of pion

    SciTech Connect

    Mello, Clayton S.; Cruz Filho, Jose P.; Da Silva, Edson O.; El-Bennich, Bruno; De Melo, J. P.; Filho, Victo S.

    2013-03-25

    In this work, we analyze the electromagnetic structure of the pion, an elementary particle composed by a quark-antiquark bound state, by considering the calculation of its electromagnetic radius and its electromagnetic form factor in low and intermediate energy range. Such observables are determined by means of a theoretical model that takes into account the constituent quark and antiquark of the pion, in the formalism of the light-front field theory. In particular, it is considered a nonsymmetrical vertex for such a model, in which we have calculated the electromagnetic form factor of the pion in an optimized way, by varying its regulator mass, so that we can obtain the best value for the pion electromagnetic radius when compared with the experimental one. The theoretical calculations are also compared with the most recent experimental data involving the pion electromagnetic form factor and the results show very good agreement.

  16. Electromagnetic compatibility overview

    NASA Astrophysics Data System (ADS)

    Davis, K. C.

    1980-07-01

    An assessment of the electromagnetic compatibility impact of the Satellite Power System is discussed. The discussion is divided into two parts: determination of the emission expected from SPS including their spatial and spectral distributions, and evaluation of the impact of such emissions on electromagnetic systems including considerations of means for mitigating effects.

  17. Introducing Electromagnetic Field Momentum

    ERIC Educational Resources Information Center

    Hu, Ben Yu-Kuang

    2012-01-01

    I describe an elementary way of introducing electromagnetic field momentum. By considering a system of a long solenoid and line charge, the dependence of the field momentum on the electric and magnetic fields can be deduced. I obtain the electromagnetic angular momentum for a point charge and magnetic monopole pair partially through dimensional

  18. Introducing Electromagnetic Field Momentum

    ERIC Educational Resources Information Center

    Hu, Ben Yu-Kuang

    2012-01-01

    I describe an elementary way of introducing electromagnetic field momentum. By considering a system of a long solenoid and line charge, the dependence of the field momentum on the electric and magnetic fields can be deduced. I obtain the electromagnetic angular momentum for a point charge and magnetic monopole pair partially through dimensional…

  19. Electromagnetically Operated Counter

    DOEpatents

    Goldberg, H.D.; Goldberg, M.I.

    1951-12-18

    An electromagnetically operated counter wherein signals to be counted are applied to cause stepwise rotation of a rotatable element which is connected to a suitable register. The mechanism involved consists of a rotatable armature having three spaced cores of magnetic material and a pair of diametrically opposed electromagnets with a suitable pulsing circuit to actuate the magnets.

  20. "Hearing" Electromagnetic Waves

    ERIC Educational Resources Information Center

    Rojo, Marta; Munoz, Juan

    2014-01-01

    In this work, an educational experience is described in which a microwave communication link is used to make students aware that all electromagnetic waves have the same physical nature and properties. Experimental demonstrations are linked to theoretical concepts to increase comprehension of the physical principles underlying electromagnetic

  1. Tunability enhanced electromagnetic wiggler

    DOEpatents

    Schlueter, R.D.; Deis, G.A.

    1992-03-24

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles. 14 figs.

  2. Tunability enhanced electromagnetic wiggler

    DOEpatents

    Schlueter, Ross D.; Deis, Gary A.

    1992-01-01

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles.

  3. Electromagnetic wave test

    NASA Astrophysics Data System (ADS)

    Matthews, R. K.; Stepanek, S. A.

    Electromagnetic wave testing, which represents a relatively new test technique that involves the union of several disciplines (aerothermodynamics, electromagnetics, materials/structures, and advanced diagnostics) is introduced. The essence of this new technique deals with the transmission and possible distortion of electromagnetic waves (RF or IR) as they pass through the bow shock, flow field, and electromagnetic window of a missile flying at hypersonic speeds. Variations in gas density along the optical path can cause significant distortion of the electromagnetic waves and, therefore the missile seeker system may not effectively track the target. Two specific test techniques are described. The first example deals with the combining of a wind tunnel and an RF range while the second example discusses the complexities of evaluating IR seeker system performance.

  4. Electromagnetism, Second Edition

    NASA Astrophysics Data System (ADS)

    Grant, I. S.; Phillips, W. R.

    2003-09-01

    The Manchester Physics Series General Editors: D. J. Sandiford; F. Mandl; A. C. Phillips Department of Physics and Astronomy, University of Manchester Properties of Matter B. H. Flowers and E. Mendoza Optics Second Edition F. G. Smith and J. H. Thomson Statistical Physics Second Edition F. Mandl Electromagnetism Second Edition I. S. Grant and W. R. Phillips Statistics R. J. Barlow Solid State Physics Second Edition J. R. Hook and H. E. Hall Quantum Mechanics F. Mandl Particle Physics Second Edition B. R. Martin and G. Shaw the Physics of Stars Second Edition A. C. Phillips Computing for Scientists R. J. Barlow and A. R. Barnett Electromagnetism, Second Edition is suitable for a first course in electromagnetism, whilst also covering many topics frequently encountered in later courses. The material has been carefully arranged and allows for flexi-bility in its use for courses of different length and structure. A knowledge of calculus and an elementary knowledge of vectors is assumed, but the mathematical properties of the differential vector operators are described in sufficient detail for an introductory course, and their physical significance in the context of electromagnetism is emphasised. In this Second Edition the authors give a fuller treatment of circuit analysis and include a discussion of the dispersion of electromagnetic waves. Electromagnetism, Second Edition features: The application of the laws of electromagnetism to practical problems such as the behaviour of antennas, transmission lines and transformers. Sets of problems at the end of each chapter to help student understanding, with hints and solutions to the problems given at the end of the book. Optional "starred" sections containing more specialised and advanced material for the more ambitious reader. An Appendix with a thorough discussion of electromagnetic standards and units. Recommended by many institutions. Electromagnetism. Second Edition has also been adopted by the Open University as the course book for its third level course on electromagnetism.

  5. Electromagnetic spatial coherence wavelets.

    PubMed

    Castaneda, Roman; Garcia-Sucerquia, Jorge

    2006-01-01

    The recently introduced concept of spatial coherence wavelets is generalized to describe the propagation of electromagnetic fields in the free space. For this aim, the spatial coherence wavelet tensor is introduced as an elementary amount, in terms of which the formerly known quantities for this domain can be expressed. It allows for the analysis of the relationship between the spatial coherence properties and the polarization state of the electromagnetic wave. This approach is completely consistent with the recently introduced unified theory of coherence and polarization for random electromagnetic beams, but it provides further insight about the causal relationship between the polarization states at different planes along the propagation path. PMID:16478063

  6. High frequency electromagnetic tomography

    SciTech Connect

    Daily, W.; Ramirez, A.; Ueng, T.; Latorre, R.

    1989-09-01

    An experiment was conducted in G Tunnel at the Nevada Test Site to evaluate high frequency electromagnetic tomography as a candidate for in situ monitoring of hydrology in the near field of a heater placed in densely welded tuff. Tomographs of 200 MHz electromagnetic permittivity were made for several planes between boreholes. Data were taken before the heater was turned on, during heating and during cooldown of the rockmass. This data is interpreted to yield maps of changes in water content of the rockmass as a function of time. This interpretation is based on laboratory measurement of electromagnetic permittivity as a function of water content for densely welded tuff. 8 refs., 6 figs.

  7. An opening electromagnetic transducer

    NASA Astrophysics Data System (ADS)

    Sun, Yanhua; Kang, Yihua

    2013-12-01

    Tubular solenoids have been widely used without any change since an electrical wire was discovered to create magnetic fields by Hans Christian Oersted in 1820 and thereby the wire was first coiled as a helix into a solenoid coil by William Sturgeon in 1823 and was improved by Joseph Henry in 1829 [see http://www.myetymology.com/encyclopedia/History_of_the_electricity.html; J. M. D. Coey, Magnetism and Magnetic Materials (Cambridge University Press, New York, 2010); and F. Winterberg, Plasma Phys. 8, 541553 (1996)]. A magnetic control method of C-shaped carrying-current wire is proposed, and thereby a new opening electromagnetic transducer evidently differing from the traditional tubular solenoid is created, capable of directly encircling and centering the acted objects in it, bringing about convenient and innovative electromagnetic energy conversion for electromagnetic heating, electromagnetic excitation, physical information capture, and electro-mechanical motion used in science research, industry, and even biomedical activities.

  8. Electromagnetism in the Movies.

    ERIC Educational Resources Information Center

    Everitt, Lori R.; Patterson, Evelyn T.

    1999-01-01

    Describes how the authors used portions of popular movies to help students review concepts related to electromagnetism. Movies used and concepts covered in the review are listed, and a sample activity is described. (WRM)

  9. Electromagnetic Fields and Cancer

    MedlinePlus

    ... ionizing Radiation, Part 2: Radiofrequency Electromagnetic Fields . Lyon, France: IARC; 2013. IARC monographs on the evaluation of ... in electric utility workers in Quebec, Canada, and France. American Journal of Epidemiology 1994; 140(9):805- ...

  10. Electromagnetic rotational actuation.

    SciTech Connect

    Hogan, Alexander Lee

    2010-08-01

    There are many applications that need a meso-scale rotational actuator. These applications have been left by the wayside because of the lack of actuation at this scale. Sandia National Laboratories has many unique fabrication technologies that could be used to create an electromagnetic actuator at this scale. There are also many designs to be explored. In this internship exploration of the designs and fabrications technologies to find an inexpensive design that can be used for prototyping the electromagnetic rotational actuator.

  11. Electromagnetic acoustic transduction using a pulsed electromagnet

    NASA Astrophysics Data System (ADS)

    Palmer, S. B.; Hernandez-Valle, J. F.; Dixon, S.

    2009-03-01

    Some early designs of Electromagnetic Acoustic Transducers (EMATs) used electromagnets to provide the strong magnetic field required for the transducer to operate. The advent of a new generation of permanent magnets such as NdFeB, with magnetic fields approaching 1T, meant that many EMAT designs switched over to using these small, compact and relatively inexpensive magnets. Typically, most modern EMATs make use of permanent magnets since they can exert high magnetic fields with compact structures. There are certain limitations when using permanent magnets, and their low Curie points of between 80-150C limit their practicality for high temperature testing without using water cooled transducers. In this work we have employed a pulsed electromagnet to provide the magnetic field. Pulsing the magnet dramatically reduces the average power required, keeping the supply more compact and less complex. It has the added advantage on ferritic steels, of resulting in much larger amplitude ultrasonic signals and improved signal to noise when compared with EMATs which use the strongest permanent magnets available.

  12. Electromagnetic attachment mechanism

    NASA Technical Reports Server (NTRS)

    Monford, Leo G., Jr. (Inventor)

    1992-01-01

    An electromagnetic attachment mechanism is disclosed for use as an end effector of a remote manipulator system. A pair of electromagnets, each with a U-shaped magnetic core with a pull-in coil and two holding coils, are mounted by a spring suspension system on a base plate of the mechanism housing with end pole pieces adapted to move through openings in the base plate when the attractive force of the electromagnets is exerted on a strike plate of a grapple fixture affixed to a target object. The pole pieces are spaced by an air gap from the strike plate when the mechanism first contacts the grapple fixture. An individual control circuit and power source is provided for the pull-in coil and one holding coil of each electromagnet. A back-up control circuit connected to the two power sources and a third power source is provided for the remaining holding coils. When energized, the pull-in coils overcome the suspension system and air gap and are automatically de-energized when the pole pieces move to grapple and impose a preload force across the grapple interface. A battery backup is a redundant power source for each electromagnet in each individual control circuit and is automatically connected upon failure of the primary source. A centerline mounted camera and video monitor are used in cooperation with a target pattern on the reflective surface of the strike plate to effect targeting and alignment.

  13. Electromagnetic particle simulation codes

    NASA Technical Reports Server (NTRS)

    Pritchett, P. L.

    1985-01-01

    Electromagnetic particle simulations solve the full set of Maxwell's equations. They thus include the effects of self-consistent electric and magnetic fields, magnetic induction, and electromagnetic radiation. The algorithms for an electromagnetic code which works directly with the electric and magnetic fields are described. The fields and current are separated into transverse and longitudinal components. The transverse E and B fields are integrated in time using a leapfrog scheme applied to the Fourier components. The particle pushing is performed via the relativistic Lorentz force equation for the particle momentum. As an example, simulation results are presented for the electron cyclotron maser instability which illustrate the importance of relativistic effects on the wave-particle resonance condition and on wave dispersion.

  14. Aircraft electromagnetic compatibility

    NASA Technical Reports Server (NTRS)

    Clarke, Clifton A.; Larsen, William E.

    1987-01-01

    Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting.

  15. EMACK electromagnetic launcher commissioning

    NASA Astrophysics Data System (ADS)

    Deis, D. W.; Scherbarth, D. W.; Ferrentino, G. L.

    1984-03-01

    The Laboratory Demonstration Electromagnetic Launcher Program (EMACK) was initiated in April 1979, with the objective to design, construct, and demonstrate a complete electromagnetic launcher (EML) system capable of accelerating projectiles of substantial mass to velocities significantly greater than those achievable with conventional chemical systems. The last hardware was installed in late 1981. During February 1982, a series of five test shots was made to evaluate the system's performance. Particular attention is given to the parameters of the final, as-built hardware, and the results of the commissioning tests. The results of these tests have demonstrated the viability of the components required for large scale electromagnetic launchers. It has been shown that large projectiles with velocities significantly greater than those achievable by chemical systems can be accelerated intact.

  16. Electromagnetic energy sink

    NASA Astrophysics Data System (ADS)

    Valagiannopoulos, C. A.; Vehmas, J.; Simovski, C. R.; Tretyakov, S. A.; Maslovski, S. I.

    2015-12-01

    The ideal black body fully absorbs all incident rays, that is, all propagating waves created by arbitrary sources. A known idealized realization of the black body is the perfectly matched layer (PML), widely used in numerical electromagnetics. However, ideal black bodies and PMLs do not interact with evanescent fields that exists near any finite-size source, and the energy stored in these fields cannot be harvested. Here, we introduce the concept of the ideal conjugate matched layer (CML), which fully absorbs the energy of both propagating and evanescent fields of sources acting as an ideal sink for electromagnetic energy. Conjugate matched absorbers have exciting application potentials, as resonant attractors of electromagnetic energy into the absorber volume. We derive the conditions on the constitutive parameters of media which can serve as CML materials, numerically study the performance of planar and cylindrical CML and discuss possible realizations of such materials as metal-dielectric composites.

  17. Electromagnetic properties of baryons

    SciTech Connect

    Ledwig, T.; Pascalutsa, V.; Vanderhaeghen, M.; Martin-Camalich, J.

    2011-10-21

    We discuss the chiral behavior of the nucleon and {Delta}(1232) electromagnetic properties within the framework of a SU(2) covariant baryon chiral perturbation theory. Our one-loop calculation is complete to the order p{sup 3} and p{sup 4}/{Delta} with {Delta} as the {Delta}(1232)-nucleon energy gap. We show that the magnetic moment of a resonance can be defined by the linear energy shift only when an additional relation between the involved masses and the applied magnetic field strength is fulfilled. Singularities and cusps in the pion mass dependence of the {Delta}(1232) electromagnetic moments reflect a non-fulfillment. We show results for the pion mass dependence of the nucleon iso-vector electromagnetic quantities and present preliminary results for finite volume effects on the iso-vector anomalous magnetic moment.

  18. Improved Electromagnetic Brake

    NASA Technical Reports Server (NTRS)

    Martin, Toby B.

    2004-01-01

    A proposed design for an electromagnetic brake would increase the reliability while reducing the number of parts and the weight, relative to a prior commercially available electromagnetic brake. The reductions of weight and the number of parts could also lead to a reduction of cost. A description of the commercial brake is prerequisite to a description of the proposed electromagnetic brake. The commercial brake (see upper part of figure) includes (1) a permanent magnet and an electromagnet coil on a stator and (2) a rotor that includes a steel contact plate mounted, with tension spring loading, on an aluminum hub. The stator is mounted securely on a stationary object, which would ordinarily be the housing of a gear drive or a motor. The rotor is mounted on the shaft of the gear drive or motor. The commercial brake nominally operates in a fail-safe (in the sense of normally braking) mode: In the absence of current in the electromagnet coil, the permanent magnet pulls the contact plate, against the spring tension, into contact with the stator. To release the brake, one excites the electromagnet with a current of the magnitude and polarity chosen to cancel the magnetic flux of the permanent magnet, thereby enabling the spring tension to pull the contact plate out of contact with the stator. The fail-safe operation of the commercial brake depends on careful mounting of the rotor in relation to the stator. The rotor/stator gap must be set with a tolerance between 10 and 15 mils (between about 0.25 and about 0.38 mm). If the gap or the contact pad is thicker than the maximum allowable value, then the permanent magnetic field will not be strong enough to pull the steel plate across the gap. (For this reason, any contact pad between the contact plate and the stator must also be correspondingly thin.) If the gap exceeds the maximum allowable value because of shaft end play, it becomes impossible to set the brake by turning off the electromagnet current. Although it may still be possible to set the brake by applying an electromagnet current to aid the permanent magnetic field instead of canceling it, this action can mask an out-of-tolerance condition in the brake and it does not restore the fail-safe function of setting the brake when current is lost.

  19. New electromagnetic conservation laws

    NASA Astrophysics Data System (ADS)

    Bergqvist, G.; Eriksson, I.; Senovilla, J. M. M.

    2003-07-01

    The Chevreton superenergy tensor was introduced in 1964 as a counterpart, for electromagnetic fields, of the well-known Bel-Robinson tensor of the gravitational field. We here prove the unnoticed facts that, in the absence of electromagnetic currents, Chevreton's tensor (i) is completely symmetric, and (ii) has a trace-free divergence if the Einstein-Maxwell equations hold. It follows that the trace of the Chevreton tensor is a rank-2, symmetric, trace-free, conserved tensor, which is different from the energy-momentum tensor, and nonetheless can be constructed for any test Maxwell field or any Einstein-Maxwell spacetime.

  20. Electromagnetic propulsion test facility

    NASA Technical Reports Server (NTRS)

    Gooder, S. T.

    1984-01-01

    A test facility for the exploration of electromagnetic propulsion concept is described. The facility is designed to accommodate electromagnetic rail accelerators of various lengths (1 to 10 meters) and to provide accelerating energies of up to 240 kiloJoules. This accelerating energy is supplied as a current pulse of hundreds of kiloAmps lasting as long as 1 millisecond. The design, installation, and operating characteristics of the pulsed energy system are discussed. The test chamber and its operation at pressures down to 1300 Pascals (10 mm of mercury) are described. Some aspects of safety (interlocking, personnel protection, and operating procedures) are included.

  1. Electromagnetic radiation detector

    DOEpatents

    Benson, Jay L.; Hansen, Gordon J.

    1976-01-01

    An electromagnetic radiation detector including a collimating window, a cathode member having a photoelectric emissive material surface angularly disposed to said window whereby radiation is impinged thereon at acute angles, an anode, separated from the cathode member by an evacuated space, for collecting photoelectrons emitted from the emissive cathode surface, and a negatively biased, high transmissive grid disposed between the cathode member and anode.

  2. "Hearing" Electromagnetic Waves

    ERIC Educational Resources Information Center

    Rojo, Marta; Munoz, Juan

    2014-01-01

    In this work, an educational experience is described in which a microwave communication link is used to make students aware that all electromagnetic waves have the same physical nature and properties. Experimental demonstrations are linked to theoretical concepts to increase comprehension of the physical principles underlying electromagnetic…

  3. Equivalence principles and electromagnetism

    NASA Technical Reports Server (NTRS)

    Ni, W.-T.

    1977-01-01

    The implications of the weak equivalence principles are investigated in detail for electromagnetic systems in a general framework. In particular, it is shown that the universality of free-fall trajectories (Galileo weak equivalence principle) does not imply the validity of the Einstein equivalence principle. However, the Galileo principle plus the universality of free-fall rotation states does imply the Einstein principle.

  4. Computational Electronics and Electromagnetics

    SciTech Connect

    DeFord, J.F.

    1993-03-01

    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 area 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.

  5. Electromagnetic structure of light nuclei

    DOE PAGESBeta

    Pastore, Saori

    2016-03-25

    Here, the present understanding of nuclear electromagnetic properties including electromagnetic moments, form factors and transitions in nuclei with A ≤ 10 is reviewed. Emphasis is on calculations based on nuclear Hamiltonians that include two- and three-nucleon realistic potentials, along with one- and two-body electromagnetic currents derived from a chiral effective field theory with pions and nucleons.

  6. Electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L. (Inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  7. ELECTROMAGNETIC RELEASE MECHANISM

    DOEpatents

    Michelson, C.

    1960-09-13

    An electromagnetic release mechanism is offered that may be used, for example, for supporting a safety rod for a nuclear reactor. The release mechanism is designed to have a large excess holding force and a rapid, uniform, and dependable release. The fast release is accomplished by providing the electromagnet with slotttd polts separated by an insulating potting resin, and by constructing the poles with a ferro-nickel alloy. The combination of these two features materially reduces the eddy current power density whenever the magnetic field changes during a release operation. In addition to these features, the design of the armature is such as to provide ready entrance of fluid into any void that might tend to form during release of the armature. This also improves the release time for the mechanism. The large holding force for the mechanism is accomplished by providing a small, selected, uniform air gap between the inner pole piece and the armature.

  8. Electromagnetic acoustic imaging.

    PubMed

    Emerson, Jane F; Chang, David B; McNaughton, Stuart; Jeong, Jong Seob; Shung, K K; Cerwin, Stephen A

    2013-02-01

    Electromagnetic acoustic imaging (EMAI) is a new imaging technique that uses long-wavelength RF electromagnetic (EM) waves to induce ultrasound emission. Signal intensity and image contrast have been found to depend on spatially varying electrical conductivity of the medium in addition to conventional acoustic properties. The resultant conductivity- weighted ultrasound data may enhance the diagnostic performance of medical ultrasound in cancer and cardiovascular applications because of the known changes in conductivity of malignancy and blood-filled spaces. EMAI has a potential advantage over other related imaging techniques because it combines the high resolution associated with ultrasound detection with the generation of the ultrasound signals directly related to physiologically important electrical properties of the tissues. Here, we report the theoretical development of EMAI, implementation of a dual-mode EMAI/ultrasound apparatus, and successful demonstrations of EMAI in various phantoms designed to establish feasibility of the approach for eventual medical applications. PMID:23357910

  9. Electromagnetic targeting of guns

    SciTech Connect

    Pogue, E.W.; Boat, R.M.; Holden, D.N.; Lopez, J.R.

    1996-10-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Electromagnetic pulse (EMP) signals produced from explosives being fired have been reported in the literature for fifty years. When a gun is fired it produces an EMP muzzle blast signal. The strength and nature of these signals was first analyzed in the early 1970s, while the results were interesting, no follow-up studies were conducted. With modern detection and signal processing technology, we believe that these signals could be used to instantaneously locate guns of virtually all calibers as they fire. The objective of our one-year project was to establish the basic nature of these signals and their utility in the concept of electromagnetic targeting of guns.

  10. DIRECT CURRENT ELECTROMAGNETIC PUMP

    DOEpatents

    Barnes, A.H.

    1957-11-01

    An improved d-c electromagnetic pump is presented in which the poles, and consequently the magetic gap at the poles, are tapered to be wider at the upstream end. In addition, the cross section of the tube carryiQ the liquid metal is tapered so that the velocity of the pumped liquid increases in the downstream direction at a rate such that the counter-induced voltage in the liquid metal remains constant as it traverses the region between the poles. This configuration compensates for the distortion of the magnetic field caused by the induced voltage that would otherwise result in the lowering of the pumping capacity. This improved electromagnetic pump as practical application in the pumping of liquid metal coolants for nuclear reactors where conventional positive displacement pumps have proved unsatisfactory due to the high temperatures and the corrosive properties of the liquid metals involved.

  11. Electromagnetic induction spectroscopy

    NASA Astrophysics Data System (ADS)

    Won, I. J.; Keiswetter, Dean A.

    1998-09-01

    An object, made partly or wholly of metals, has a distinct combination of electrical conductivity, magnetic permeability, and geometrical shape and size. When the object is exposed to a low-frequency electromagnetic field, it produces a secondary magnetic field. By measuring the secondary field in a broadband spectrum, we obtain a distinct spectral signature that may uniquely identify the object. Based on the response spectrum, we attempt to 'fingerprint' the object. This is the basic concept of Electromagnetic Induction Spectroscopy (EMIS). EMIS technology may be particularly useful for detecting buried landmines and unexploded ordnance. By fully characterizing and identifying an object without excavation. We should be able to reduce significantly the number of false targets. EMIS should be fully applicable to many other problems where target identification and recognition (without intrusive search) are important. For instance, an advanced EMIS device at an airport security gate may be able to recognize a particular weapon by its maker and type.

  12. Metamaterials in electromagnetics

    NASA Astrophysics Data System (ADS)

    Sihvola, Ari

    2007-03-01

    This article takes a look at metamaterials in electromagnetics from a general point of view. The terminology of complex electromagnetic materials is discussed critically. A unique definition for metamaterials does not exist, but certain salient points can be distinguished in the ongoing discussion within the research community and in various formal suggestions for this definition in the literature. Also several different classes of special materials are identified as candidates for metamaterials and their particular characteristics are discussed. Finally it is pointed out that the boundary between "ordinary" materials and metamaterials is difficult to draw because also many everyday natural materials are dielectric mixtures which may display very surprising and non-linear macroscopic response functions.

  13. Method of electromagnetic exploration

    SciTech Connect

    Nekut, A.G. Jr.

    1987-05-05

    A method is described of electromagnetic exploration comprising the following steps: obtaining measures of two horizontal components of the earth's magnetic field at each reference sites; obtaining a measure of the vertical component of the earth's magnetic field for at least one exploratory site; and determining a measure of a multidimensional earth resistivity structure by correlating the measures of horizontal and vertical components of the earth's magnetic field.

  14. Banded electromagnetic stator core

    DOEpatents

    Fanning, A.W.; Gonzales, A.A.; Patel, M.R.; Olich, E.E.

    1996-06-11

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups. 5 figs.

  15. Banded electromagnetic stator core

    DOEpatents

    Fanning, A.W.; Gonzales, A.A.; Patel, M.R.; Olich, E.E.

    1994-04-05

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups. 5 figures.

  16. Earth's Electromagnetic Environment

    NASA Astrophysics Data System (ADS)

    Constable, Catherine

    2016-01-01

    The natural spectrum of electromagnetic variations surrounding Earth extends across an enormous frequency range and is controlled by diverse physical processes. Electromagnetic (EM) induction studies make use of external field variations with frequencies ranging from the solar cycle which has been used for geomagnetic depth sounding through the 10^{-4}-10^4 Hz frequency band widely used for magnetotelluric and audio-magnetotelluric studies. Above 10^4 Hz, the EM spectrum is dominated by man-made signals. This review emphasizes electromagnetic sources at ˜1 Hz and higher, describing major differences in physical origin and structure of short- and long-period signals. The essential role of Earth's internal magnetic field in defining the magnetosphere through its interactions with the solar wind and interplanetary magnetic field is briefly outlined. At its lower boundary, the magnetosphere is engaged in two-way interactions with the underlying ionosphere and neutral atmosphere. Extremely low-frequency (3 Hz-3 kHz) electromagnetic signals are generated in the form of sferics, lightning, and whistlers which can extend to frequencies as high as the VLF range (3-30 kHz).The roughly spherical dielectric cavity bounded by the ground and the ionosphere produces the Schumann resonance at around 8 Hz and its harmonics. A transverse resonance also occurs at 1.7-2.0 kHz arising from reflection off the variable height lower boundary of the ionosphere and exhibiting line splitting due to three-dimensional structure. Ground and satellite observations are discussed in the light of their contributions to understanding the global electric circuit and for EM induction studies.

  17. Banded electromagnetic stator core

    DOEpatents

    Fanning, Alan W.; Gonzales, Aaron A.; Patel, Mahadeo R.; Olich, Eugene E.

    1994-01-01

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

  18. Banded electromagnetic stator core

    DOEpatents

    Fanning, Alan W.; Gonzales, Aaron A.; Patel, Mahadeo R.; Olich, Eugene E.

    1996-01-01

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

  19. Electromagnetically coupled microstrip dipoles

    NASA Astrophysics Data System (ADS)

    Oltman, H. G.; Huebner, D. A.

    1981-01-01

    A new class of printed circuit radiator consisting of a microstrip dipole electromagnetically coupled to a microstrip feed line is described. Several configurations which differ in bandwidth, efficiency, and construction simplicity are presented. A geometry which has been found to be optimum for many applications is noted. Radiation characteristics of both isolated elements and arrays of elements are examined. Experimental and theoretical results are presented.

  20. Electromagnetic tornadoes in space

    SciTech Connect

    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.

  1. Earth's Electromagnetic Environment

    NASA Astrophysics Data System (ADS)

    Constable, Catherine

    2015-12-01

    The natural spectrum of electromagnetic variations surrounding Earth extends across an enormous frequency range and is controlled by diverse physical processes. Electromagnetic (EM) induction studies make use of external field variations with frequencies ranging from the solar cycle which has been used for geomagnetic depth sounding through the 10^{-4} -10^4 Hz frequency band widely used for magnetotelluric and audio-magnetotelluric studies. Above 10^4 Hz, the EM spectrum is dominated by man-made signals. This review emphasizes electromagnetic sources at ˜ 1 Hz and higher, describing major differences in physical origin and structure of short- and long-period signals. The essential role of Earth's internal magnetic field in defining the magnetosphere through its interactions with the solar wind and interplanetary magnetic field is briefly outlined. At its lower boundary, the magnetosphere is engaged in two-way interactions with the underlying ionosphere and neutral atmosphere. Extremely low-frequency (3 Hz-3 kHz) electromagnetic signals are generated in the form of sferics, lightning, and whistlers which can extend to frequencies as high as the VLF range (3-30 kHz).The roughly spherical dielectric cavity bounded by the ground and the ionosphere produces the Schumann resonance at around 8 Hz and its harmonics. A transverse resonance also occurs at 1.7-2.0 kHz arising from reflection off the variable height lower boundary of the ionosphere and exhibiting line splitting due to three-dimensional structure. Ground and satellite observations are discussed in the light of their contributions to understanding the global electric circuit and for EM induction studies.

  2. Electromagnetically induced conical emission

    SciTech Connect

    Becerra-Castro, E. M.; Araujo, Luis E. E. de

    2010-12-15

    We describe theoretically a scheme for observing conical emission, a transverse nonlinear optical effect, in an atomic vapor with all excitation fields below the saturation level of the involved atomic transitions. The scheme relies on the giant Kerr nonlinearities possible under electromagnetically induced transparency to introduce a radially varying phase shift to a weak probe field by a weak signal field. The probe's far-field diffraction pattern shows multiple concentric rings around the probe beam's axis, characteristic of conical emission.

  3. Nuclear Electromagnetic Pulse Review

    NASA Astrophysics Data System (ADS)

    Dinallo, Michael

    2011-04-01

    Electromagnetic Pulse (EMP) from nuclear detonations have been observed for well over half a century. Beginning in the mid-to-late 1950s, the physics and modeling of EMP has been researched and will continue into the foreseeable future. The EMP environment propagates hundreds of miles from its origins and causes interference for all types of electronic instrumentation. This includes military, municipal and industry based electronic infrastructures such as power generation and distribution, command and control systems, systems used in financial and emergency services, electronic monitoring and communications networks, to mention some key infrastructure elements. Research into EMP has included originating physics, propagation and electromagnetic field coupling analyses and measurement-sensor development. Several methods for calculating EMP induced transient interference (voltage and current induction) will be briefly discussed and protection techniques reviewed. These methods can be mathematically simple or involve challenging boundary value solution techniques. A few illustrative calculations will demonstrate the concern for electronic system operability. Analyses such as the Wunsch-Bell model for electronic upset or damage, and the Singularity Expansion Method (SEM) put forth by Dr. Carl Baum, will facilitate the concern for EMP effects. The SEM determines the voltages and currents induced from transient electromagnetic fields in terms of natural modes of various types of electronic platforms (aerospace vehicles or land-based assets - fixed or mobile). Full-scale facility and laboratory simulation and response measurement approaches will be discussed. The talk will conclude with a discussion of some present research activities.

  4. Gravito-electromagnetic analogies

    NASA Astrophysics Data System (ADS)

    Costa, L. Filipe O.; Natário, José

    2014-10-01

    We reexamine and further develop different gravito-electromagnetic (GEM) analogies found in the literature, and clarify the connection between them. Special emphasis is placed in two exact physical analogies: the analogy based on inertial fields from the so-called "1+3 formalism", and the analogy based on tidal tensors. Both are reformulated, extended and generalized. We write in both formalisms the Maxwell and the full exact Einstein field equations with sources, plus the algebraic Bianchi identities, which are cast as the source-free equations for the gravitational field. New results within each approach are unveiled. The well known analogy between linearized gravity and electromagnetism in Lorentz frames is obtained as a limiting case of the exact ones. The formal analogies between the Maxwell and Weyl tensors are also discussed, and, together with insight from the other approaches, used to physically interpret gravitational radiation. The precise conditions under which a similarity between gravity and electromagnetism occurs are discussed, and we conclude by summarizing the main outcome of each approach.

  5. Coherent hybrid electromagnetic field imaging

    DOEpatents

    Cooke, Bradly J.; Guenther, David C.

    2008-08-26

    An apparatus and corresponding method for coherent hybrid electromagnetic field imaging of a target, where an energy source is used to generate a propagating electromagnetic beam, an electromagnetic beam splitting means to split the beam into two or more coherently matched beams of about equal amplitude, and where the spatial and temporal self-coherence between each two or more coherently matched beams is preserved. Two or more differential modulation means are employed to modulate each two or more coherently matched beams with a time-varying polarization, frequency, phase, and amplitude signal. An electromagnetic beam combining means is used to coherently combine said two or more coherently matched beams into a coherent electromagnetic beam. One or more electromagnetic beam controlling means are used for collimating, guiding, or focusing the coherent electromagnetic beam. One or more apertures are used for transmitting and receiving the coherent electromagnetic beam to and from the target. A receiver is used that is capable of square-law detection of the coherent electromagnetic beam. A waveform generator is used that is capable of generation and control of time-varying polarization, frequency, phase, or amplitude modulation waveforms and sequences. A means of synchronizing time varying waveform is used between the energy source and the receiver. Finally, a means of displaying the images created by the interaction of the coherent electromagnetic beam with target is employed.

  6. Electromagnetic Meissner-Effect Launcher

    NASA Technical Reports Server (NTRS)

    Robertson, Glen A.

    1990-01-01

    Proposed electromagnetic Meissner-effect launching apparatus differs from previous electromagnetic launchers; no need for electromagnet coil on projectile. Result, no need for brush contacts and high-voltage commutation equipment to supply current directly to projectile coil, or for pulse circuitry to induce current in projectile coil if brush contacts not used. Compresses magnetic field surrounding rear surface of projectile, creating gradient of magnetic pressure pushing projectile forward.

  7. Electromagnetic production of hypernuclei

    SciTech Connect

    Ventel, B.I.S. van der; Mart, T.; Lue, H.-F.; Yadav, H.L.; Hillhouse, G.C.

    2011-05-15

    Highlights: {yields}General formalism for electromagnetic production of hypernuclei. > Most recent form of the electromagnetic current operator for elementary process. > Fully relativistic description of bound state wave functions. > Unpolarized cross section determined by three structure functions. - Abstract: A formalism for the electromagnetic production of hypernuclei is developed where the cross section is written as a contraction between a leptonic tensor and a hadronic tensor. The hadronic tensor is written in a model-independent way by expanding it in terms of a set of five nuclear structure functions. These structure functions are calculated by assuming that the virtual photon interacts with only one bound nucleon. We use the most recent model for the elementary current operator which gives a good description of the experimental data for the corresponding elementary process. The bound state wave functions for the bound nucleon and hyperon are calculated within a relativistic mean-field model. We calculate the unpolarized triple differential cross section for the hypernuclear production process e+{sup 12}C{yields}e+K{sup +}+{sup 12}{sub {Lambda}B} as a function of the kaon scattering angle. The nuclear structure functions are calculated within a particle-hole model. The cross section displays a characteristic form of being large for small values of the kaon scattering angle with a smooth fall-off to zero with increasing angle. The shape of the cross section is essentially determined by the nuclear structure functions. In addition, it is found that for the unpolarized triple differential cross section one structure function is negligible over the entire range of the kaon scattering angle.

  8. Electromagnetic Meissner effect launcher

    NASA Technical Reports Server (NTRS)

    Robertson, Glen A. (Inventor)

    1991-01-01

    An electromagnetic projectile launcher provides acceleration of a superconducting projectile through the diamagnetic repulsion of the superconducting projectile. A superconducting layer is provided aft of the projectile, either directly on the projectile or on a platform upon which the projectile is carried, and a traveling magnetic field is caused to propagate along a magnetic field drive coil in which the projectile is disposed. The resulting diamagnetic repulsion between the superconducting projectile and the traveling magnetic field causes the projectile to be propelled along the coil. In one embodiment, a segmented drive coil is used to generate the traveling magnetic field.

  9. Electromagnetically induced holographic imaging

    NASA Astrophysics Data System (ADS)

    Qiu, Tianhui; Xia, Lixin; Ma, Hongyang; Zheng, Chunhong; Chen, Libo

    2016-01-01

    The electromagnetically induced Talbot effect offers a nondestructive and lensless way to image ultracold atoms or molecules (Wen et al., 2011 [12]). In this paper, we propose another atomic imaging scheme based on the holographic imaging principle, in which three types of light source are employed as the imaging light to perform spatial interference. Compared to the previous self-imaging scheme, in the present one both the amplitude and phase information of the object can be imaged with the characteristic of arbitrarily controllable image variation in size, and the object to be imaged is no longer subject to the periodic structure.

  10. Electromagnetic transitions in hypernuclei

    SciTech Connect

    Chrien, R.E.

    1986-01-01

    The object of this review is to survey observations of electromagnetic transitions in hypernuclei and to point out contributions of these observations to an understanding of the effective two-body hyperon-nucleon forces in the nucleus. The discussion concentrates on lambda-hyperon nucleon potentials. Future plans for high resolution hypernuclear spectroscopy using Ge diode detectors is discussed, especially regarding the window of utility of such devices. Expected improvements in beam facilities are also reviewed. 9 refs., 4 figs., 1 tab. (DWL)

  11. Electromagnetic levitation applications

    SciTech Connect

    Bayazitoglu, Y.

    1996-11-01

    At high temperatures, most materials react with the walls of their containers. This inevitably leads to material contamination and property degradation. Therefore, it becomes difficult to process materials to the required degree of purity and/or measure their properties at high temperatures. Levitation melting has been used on earth and microgravity since to circumvent this problem. In this paper, first a broad survey of the work done in electromagnetic levitation since its invention is given. Then the heat generation due to an alternating magnetic field is studied. Finally, the application of levitation melting in the determination of thermal diffusivity, emissivity, surface tension and viscosity of liquid metals is presented.

  12. Snow Electromagnetic Measurements

    NASA Technical Reports Server (NTRS)

    Linlor, W. I.; Smith, J. L.; Clapp, F. D.; Angelakos, D. J.

    1980-01-01

    An electromagnetic system is described for measuring the dielectric constant and attenuation of snow samples in the frequency range of 4 to 12 GHz. System components consists of a swept-frequency source, microwave horns, network analyzer, and XY plotter. The procedure for calibrating the effect of wetness on the snow properties is described. Equations are given that express the experimentally determined relation between attenuation per unit length and volume percent wetness at any frequency between 4 and 12 GHz. permittivity can be calculated from the snow density, attenuation per unit length, and frequency. Some applications of the techniques are described such as runoff forecasting from mountain snowpacks.

  13. The CMS Electromagnetic Calorimeter

    NASA Astrophysics Data System (ADS)

    Ryan, M.

    2008-06-01

    The CMS experiment at the CERN Large Hadron Collider has placed great emphasis on precise calorimetry. The electromagnetic calorimeter (ECAL) contains 75000 scintillating lead tungstate crystals that are read out using sophisticated electronics; this paper describes these technologies and how they were implemented in the calorimeter. The results of pre-calibration measurements for the detector modules are detailed. Installation of the ECAL into the underground cavern has commenced and the commissioning process and its status are discussed. The experiment is scheduled to start in 2008 and prospects for the first year of operation and running are given.

  14. Electromagnetic pump stator coil

    DOEpatents

    Fanning, A.W.; Dahl, L.R.

    1996-06-25

    An electrical stator coil for an electromagnetic pump includes a continuous conductor strip having first and second terminals at opposite ends thereof and an intermediate section disposed therebetween. The strip is configured in first and second coil halves, with the first coil half including a plurality of windings extending from the first terminal to the intermediate section, and the second coil half including a plurality of windings extending from the second terminal to the intermediate section. The first and second coil halves are disposed coaxially, and the first and second terminals are disposed radially inwardly therefrom with the intermediate section being disposed radially outwardly therefrom. 9 figs.

  15. Electromagnetic pump stator coil

    DOEpatents

    Fanning, Alan W.; Dahl, Leslie R.

    1996-01-01

    An electrical stator coil for an electromagnetic pump includes a continuous conductor strip having first and second terminals at opposite ends thereof and an intermediate section disposed therebetween. The strip is configured in first and second coil halves, with the first coil half including a plurality of windings extending from the first terminal to the intermediate section, and the second coil half including a plurality of windings extending from the second terminal to the intermediate section. The first and second coil halves are disposed coaxially, and the first and second terminals are disposed radially inwardly therefrom with the intermediate section being disposed radially outwardly therefrom.

  16. The ALICE Electromagnetic Calorimeter

    SciTech Connect

    Awes, Terry C; ALICE, Collaboration

    2010-01-01

    ALICE is the general purpose experiment at the LHC dedicated to the study of heavy-ion collisions. The electromagnetic calorimeter (EMCal) is a late addition to the ALICE suite of detectors with first modules installed in ALICE this year. The EMCal is designed to trigger on high energy gamma-rays and jets, and to enhance the capabilities of ALICE for these measurements. The EMCal is a Pb/scintillator sampling shish-kebab type calorimeter. The EMCal construction, readout, and performance in beam tests at the CERN SPS and PS are described.

  17. The ALICE Electromagnetic Calorimeter

    SciTech Connect

    Awes, Terry C; ALICE, Collaboration

    2010-05-01

    ALICE is the general purpose experiment at the LHC dedicated to the study of heavy-ion collisions. The electromagnetic calorimeter (EMCal) is a late addition to the ALICE suite of detectors with first modules installed in ALICE this year. The EMCal is designed to trigger on high energy gamma-rays and jets, and to enhance the capabilities of ALICE for these measurements. The EMCal is a Pb/scintillator sampling shish-kebab type calorimeter. The EMCal construction, readout, and performance in beam tests at the CERN SPS and PS are described.

  18. Electromagnetic propulsion for spacecraft

    NASA Technical Reports Server (NTRS)

    Myers, Roger M.

    1993-01-01

    Three electromagnetic propulsion technologies, solid propellant pulsed plasma thrusters (PPT), magnetoplasmadynamic (MPD) thrusters, and pulsed inductive thrusters (PIT), were developed for application to auxiliary and primary spacecraft propulsion. Both the PPT and MPD thrusters were flown in space, though only PPT's were used on operational satellites. The performance of operational PPT's is quite poor, providing only approximately 8 percent efficiency at approximately 1000 s specific impulse. However, laboratory PPT's yielding 34 percent efficiency at 2000 s specific impulse were extensively tested, and peak performance levels of 53 percent efficiency at 5170 s specific impulse were demonstrated. MPD thrusters were flown as experiments on the Japanese MS-T4 spacecraft and the Space Shuttle and were qualified for a flight in 1994. The flight MPD thrusters were pulsed, with a peak performance of 22 percent efficiency at 2500 s specific impulse using ammonia propellant. Laboratory MPD thrusters were demonstrated with up to 70 percent efficiency and 700 s specific impulse using lithium propellant. While the PIT thruster has never been flown, recent performance measurements using ammonia and hydrazine propellants are extremely encouraging, reaching 50 percent efficiency for specific impulses between 4000 to 8000 s. The fundamental operating principles, performance measurements, and system level design for the three types of electromagnetic thrusters are reviewed, and available data on flight tests are discussed for the PPT and MPD thrusters.

  19. Electromagnetic propulsion for spacecraft

    NASA Astrophysics Data System (ADS)

    Myers, Roger M.

    1993-09-01

    Three electromagnetic propulsion technologies, solid propellant pulsed plasma thrusters (PPT), magnetoplasmadynamic (MPD) thrusters, and pulsed inductive thrusters (PIT), were developed for application to auxiliary and primary spacecraft propulsion. Both the PPT and MPD thrusters were flown in space, though only PPT's were used on operational satellites. The performance of operational PPT's is quite poor, providing only approximately 8 percent efficiency at approximately 1000 s specific impulse. However, laboratory PPT's yielding 34 percent efficiency at 2000 s specific impulse were extensively tested, and peak performance levels of 53 percent efficiency at 5170 s specific impulse were demonstrated. MPD thrusters were flown as experiments on the Japanese MS-T4 spacecraft and the Space Shuttle and were qualified for a flight in 1994. The flight MPD thrusters were pulsed, with a peak performance of 22 percent efficiency at 2500 s specific impulse using ammonia propellant. Laboratory MPD thrusters were demonstrated with up to 70 percent efficiency and 700 s specific impulse using lithium propellant. While the PIT thruster has never been flown, recent performance measurements using ammonia and hydrazine propellants are extremely encouraging, reaching 50 percent efficiency for specific impulses between 4000 to 8000 s. The fundamental operating principles, performance measurements, and system level design for the three types of electromagnetic thrusters are reviewed, and available data on flight tests are discussed for the PPT and MPD thrusters.

  20. Metamaterials beyond electromagnetism.

    PubMed

    Kadic, Muamer; Bückmann, Tiemo; Schittny, Robert; Wegener, Martin

    2013-12-01

    Metamaterials are rationally designed man-made structures composed of functional building blocks that are densely packed into an effective (crystalline) material. While metamaterials are mostly associated with negative refractive indices and invisibility cloaking in electromagnetism or optics, the deceptively simple metamaterial concept also applies to rather different areas such as thermodynamics, classical mechanics (including elastostatics, acoustics, fluid dynamics and elastodynamics), and, in principle, also to quantum mechanics. We review the basic concepts, analogies and differences to electromagnetism, and give an overview on the current state of the art regarding theory and experiment-all from the viewpoint of an experimentalist. This review includes homogeneous metamaterials as well as intentionally inhomogeneous metamaterial architectures designed by coordinate-transformation-based approaches analogous to transformation optics. Examples are laminates, transient thermal cloaks, thermal concentrators and inverters, 'space-coiling' metamaterials, anisotropic acoustic metamaterials, acoustic free-space and carpet cloaks, cloaks for gravitational surface waves, auxetic mechanical metamaterials, pentamode metamaterials ('meta-liquids'), mechanical metamaterials with negative dynamic mass density, negative dynamic bulk modulus, or negative phase velocity, seismic metamaterials, cloaks for flexural waves in thin plates and three-dimensional elastostatic cloaks. PMID:24190877

  1. Electromagnetically Induced Entanglement

    PubMed Central

    Yang, Xihua; Xiao, Min

    2015-01-01

    Quantum entanglement provides an essential resource for quantum computation, quantum communication, and quantum network. How to conveniently and efficiently produce entanglement between bright light beams presents a challenging task to build realistic quantum information processing networks. Here, we present an efficient and convenient way to realize a novel quantum phenomenon, named electromagnetically induced entanglement, in the conventional Λ-type three-level atomic system driven by a strong pump field and a relatively weak probe field. Nearly perfect entanglement between the two fields can be achieved with a low coherence decay rate between the two lower levels, high pump-field intensity, and large optical depth of the atomic ensemble. The physical origin is quantum coherence between the lower doublet produced by the pump and probe fields, similar to the well-known electromagnetically induced transparency. This method would greatly facilitate the generation of nondegenerate narrow-band continuous-variable entanglement between bright light beams by using only coherent laser fields, and may find potential and broad applications in realistic quantum information processing. PMID:26314514

  2. Electromagnetically Induced Entanglement

    NASA Astrophysics Data System (ADS)

    Yang, Xihua; Xiao, Min

    2015-08-01

    Quantum entanglement provides an essential resource for quantum computation, quantum communication, and quantum network. How to conveniently and efficiently produce entanglement between bright light beams presents a challenging task to build realistic quantum information processing networks. Here, we present an efficient and convenient way to realize a novel quantum phenomenon, named electromagnetically induced entanglement, in the conventional Λ-type three-level atomic system driven by a strong pump field and a relatively weak probe field. Nearly perfect entanglement between the two fields can be achieved with a low coherence decay rate between the two lower levels, high pump-field intensity, and large optical depth of the atomic ensemble. The physical origin is quantum coherence between the lower doublet produced by the pump and probe fields, similar to the well-known electromagnetically induced transparency. This method would greatly facilitate the generation of nondegenerate narrow-band continuous-variable entanglement between bright light beams by using only coherent laser fields, and may find potential and broad applications in realistic quantum information processing.

  3. Electromagnetic Field Penetration Studies

    NASA Technical Reports Server (NTRS)

    Deshpande, M.D.

    2000-01-01

    A numerical method is presented to determine electromagnetic shielding effectiveness of rectangular enclosure with apertures on its wall used for input and output connections, control panels, visual-access windows, ventilation panels, etc. Expressing EM fields in terms of cavity Green's function inside the enclosure and the free space Green's function outside the enclosure, integral equations with aperture tangential electric fields as unknown variables are obtained by enforcing the continuity of tangential electric and magnetic fields across the apertures. Using the Method of Moments, the integral equations are solved for unknown aperture fields. From these aperture fields, the EM field inside a rectangular enclosure due to external electromagnetic sources are determined. Numerical results on electric field shielding of a rectangular cavity with a thin rectangular slot obtained using the present method are compared with the results obtained using simple transmission line technique for code validation. The present technique is applied to determine field penetration inside a Boeing-757 by approximating its passenger cabin as a rectangular cavity filled with a homogeneous medium and its passenger windows by rectangular apertures. Preliminary results for, two windows, one on each side of fuselage were considered. Numerical results for Boeing-757 at frequencies 26 MHz, 171-175 MHz, and 428-432 MHz are presented.

  4. Teratogen update: electromagnetic fields.

    PubMed

    Robert, E

    1996-12-01

    Public concern is increasing about the potential health effects of extremely low frequency (ELF) electromagnetic fields (EMFs) naturally present or generated by electrical appliances and those of very low frequency (VLF) fields, like those generated by video display terminals (VDTs). There are arguments in favour of EMFs being biologically active but no mechanism has been identified that explains the link between EMFs and bioeffects. More than 50 studies on exposures of animals to EMFs have been performed within the last few years. Although there were a few statistically significant effects in the studies reviewed, no replicable results were found among laboratories. The extent of effects observed, if any, was always low, and deserves further investigation before relevance to humans can be considered. Human data reviewed concern the potential reproductive effects (mainly) spontaneous abortions, low birthweight, and congenital malformations) of exposure to various sources of EMFs: maternal residence, heated waterbeds, electric blankets, and ceiling heating coils, occupational exposure (mainly video display terminals), and magnetic resonance imaging. The totality of the evidence that is thus far available provides no convincing evidence to indicate that low frequency EMFs of the sort that might be met in occupational or daily life exposures does any harm to the human reproductive process. It is suggested that those counseling pregnant women follow the guidelines established by WHO in agreement with the International Non-ionizing Radiation Committee. This group does not consider that the results of published studies provide a basis for restricting human exposure to electromagnetic fields and radiation. PMID:9098925

  5. Exploration of the Electromagnetic Environment

    ERIC Educational Resources Information Center

    Fullekrug, M.

    2009-01-01

    The electromagnetic environment is composed of electric and magnetic fields which result from man-made and natural sources. An elementary experiment is described to explore the electromagnetic environment by measuring electric fields in the frequency range from approximately equal to 10 to 24 000 Hz. The equipment required to conduct the…

  6. Electromagnetic direct implicit PIC simulation

    SciTech Connect

    Langdon, A.B.

    1983-03-29

    Interesting modelling of intense electron flow has been done with implicit particle-in-cell simulation codes. In this report, the direct implicit PIC simulation approach is applied to simulations that include full electromagnetic fields. The resulting algorithm offers advantages relative to moment implicit electromagnetic algorithms and may help in our quest for robust and simpler implicit codes.

  7. Electromagnetics laboratory annual report, 1994

    NASA Astrophysics Data System (ADS)

    Lindell, I. V.; Sihvola, A. H.

    1995-01-01

    Activities of the Electromagnetics Laboratory during 1994 are described in this report. As highlights of the output stand the monographs Electromagnetic Waves in Chiral and Bi-Isotropic Media (Artech House, Boston) and History of Electrical Engineering (Otatieto, Espoo, in Finnish). Also, the total number of papers published and accepted for publication in international refereed journals show a new record, 40 items.

  8. Gravitational scattering of electromagnetic radiation

    NASA Technical Reports Server (NTRS)

    Brooker, J. T.; Janis, A. I.

    1980-01-01

    The scattering of electromagnetic radiation by linearized gravitational fields is studied to second order in a perturbation expansion. The incoming electromagnetic radiation can be of arbitrary multipole structure, and the gravitational fields are also taken to be advanced fields of arbitrary multipole structure. All electromagnetic multipole radiation is found to be scattered by gravitational monopole and time-varying dipole fields. No case has been found, however, in which any electromagnetic multipole radiation is scattered by gravitational fields of quadrupole or higher-order multipole structure. This lack of scattering is established for infinite classes of special cases, and is conjectured to hold in general. The results of the scattering analysis are applied to the case of electromagnetic radiation scattered by a moving mass. It is shown how the mass and velocity may be determined by a knowledge of the incident and scattered radiation.

  9. Electromagnetic scattering theory

    NASA Technical Reports Server (NTRS)

    Bird, J. F.; Farrell, R. A.

    1986-01-01

    Electromagnetic scattering theory is discussed with emphasis on the general stochastic variational principle (SVP) and its applications. The stochastic version of the Schwinger-type variational principle is presented, and explicit expressions for its integrals are considered. Results are summarized for scalar wave scattering from a classic rough-surface model and for vector wave scattering from a random dielectric-body model. Also considered are the selection of trial functions and the variational improvement of the Kirchhoff short-wave approximation appropriate to large size-parameters. Other applications of vector field theory discussed include a general vision theory and the analysis of hydromagnetism induced by ocean motion across the geomagnetic field. Levitational force-torque in the magnetic suspension of the disturbance compensation system (DISCOS), now deployed in NOVA satellites, is also analyzed using the developed theory.

  10. Nucleon Electromagnetic Form Factors

    SciTech Connect

    Marc Vanderhaeghen; Charles Perdrisat; Vina Punjabi

    2007-10-01

    There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has greatly improved by performing double polarization experiments, in comparison with previous unpolarized data. Here we review the experimental data base in view of the new results for the proton, and neutron, obtained at JLab, MAMI, and MIT-Bates. The rapid evolution of phenomenological models triggered by these high-precision experiments will be discussed, including the recent progress in the determination of the valence quark generalized parton distributions of the nucleon, as well as the steady rate of improvements made in the lattice QCD calculations.

  11. Pulsed electromagnetic gas acceleration

    NASA Technical Reports Server (NTRS)

    Jahn, R. G.; Vonjaskowsky, W. F.; Clark, K. E.

    1971-01-01

    Experimental data were combined with one-dimensional conservation relations to yield information on the energy deposition ratio in a parallel-plate accelerator, where the downstream flow was confined to a constant area channel. Approximately 70% of the total input power was detected in the exhaust flow, of which only about 20% appeared as directed kinetic energy, thus implying that a downstream expansion to convert chamber enthalpy into kinetic energy must be an important aspect of conventional high power MPD arcs. Spectroscopic experiments on a quasi-steady MPD argon accelerator verified the presence of A(III) and the absence of A(I), and indicated an azimuthal structure in the jet related to the mass injection locations. Measurements of pressure in the arc chamber and impact pressure in the exhaust jet using a piezocrystal backed by a Plexiglas rod were in good agreement with the electromagnetic thrust model.

  12. Wavelets and electromagnetics

    NASA Technical Reports Server (NTRS)

    Kempel, Leo C.

    1992-01-01

    Wavelets are an exciting new topic in applied mathematics and signal processing. This paper will provide a brief review of wavelets which are also known as families of functions with an emphasis on interpretation rather than rigor. We will derive an indirect use of wavelets for the solution of integral equations based techniques adapted from image processing. Examples for resistive strips will be given illustrating the effect of these techniques as well as their promise in reducing dramatically the requirement in order to solve an integral equation for large bodies. We also will present a direct implementation of wavelets to solve an integral equation. Both methods suggest future research topics and may hold promise for a variety of uses in computational electromagnetics.

  13. Electromagnetic propulsion for spacecraft

    NASA Technical Reports Server (NTRS)

    Myers, Roger M.

    1993-01-01

    Three electromagnetic propulsion technologies, solid propellant pulsed plasma thrusters (PPT), magnetoplasmadynamic (MPD) thrusters, and pulsed inductive thrusters (PIT) have been developed for application to auxiliary and primary spacecraft propulsion. Both the PPT and MPD thrusters have been flown in space, though only PPTs have been used on operational satellites. The performance of operational PPTs is quite poor, providing only about 8 percent efficiency at about 1000 sec specific impulse. Laboratory PPTs yielding 34 percent efficiency at 5170 sec specific impulse have been demonstrated. Laboratory MPD thrusters have been demonstrated with up to 70 percent efficiency and 7000 sec specific impulse. Recent PIT performance measurements using ammonia and hydrazine propellants are extremely encouraging, reaching 50 percent efficiency for specific impulses between 4000 and 8000 sec.

  14. Electromagnetically Clean Solar Arrays

    NASA Technical Reports Server (NTRS)

    Stem, Theodore G.; Kenniston, Anthony E.

    2008-01-01

    The term 'electromagnetically clean solar array' ('EMCSA') refers to a panel that contains a planar array of solar photovoltaic cells and that, in comparison with a functionally equivalent solar-array panel of a type heretofore used on spacecraft, (1) exhibits less electromagnetic interferences to and from other nearby electrical and electronic equipment and (2) can be manufactured at lower cost. The reduction of electromagnetic interferences is effected through a combination of (1) electrically conductive, electrically grounded shielding and (2) reduction of areas of current loops (in order to reduce magnetic moments). The reduction of cost is effected by designing the array to be fabricated as a more nearly unitary structure, using fewer components and fewer process steps. Although EMCSAs were conceived primarily for use on spacecraft they are also potentially advantageous for terrestrial applications in which there are requirements to limit electromagnetic interference. In a conventional solar panel of the type meant to be supplanted by an EMCSA panel, the wiring is normally located on the back side, separated from the cells, thereby giving rise to current loops having significant areas and, consequently, significant magnetic moments. Current-loop geometries are chosen in an effort to balance opposing magnetic moments to limit far-0field magnetic interactions, but the relatively large distances separating current loops makes full cancellation of magnetic fields problematic. The panel is assembled from bare photovoltaic cells by means of multiple sensitive process steps that contribute significantly to cost, especially if electomagnetic cleanliness is desired. The steps include applying a cover glass and electrical-interconnect-cell (CIC) sub-assemble, connecting the CIC subassemblies into strings of series-connected cells, laying down and adhesively bonding the strings onto a panel structure that has been made in a separate multi-step process, and mounting the wiring on the back of the panel. Each step increases the potential for occurrence of latent defects, loss of process control, and attrition of components. An EMCSA panel includes an integral cover made from a transparent material. The silicone cover supplants the individual cover glasses on the cells and serves as an additional unitary structural support that offers the advantage, relative to glass, of the robust, forgiving nature of the silcone material. The cover contains pockets that hold the solar cells in place during the lamination process. The cover is coated with indium tin oxide to make its surface electrically conductive, so that it serves as a contiguous, electrically grounded shield over the entire panel surface. The cells are mounted in proximity to metallic printed wiring. The painted-wiring layer comprises metal-film traces on a sheet of Kapton (or equivalent) polyimide. The traces include contact pads on one side of the sheet for interconnecting the cells. Return leads are on the opposite side of the sheet, positioned to form the return currents substantially as mirror images of, and in proximity to, the cell sheet currents, thereby minimizing magnetic moments. The printed-wiring arrangement mimics the back-wiring arrangement of conventional solar arrays, but the current-loop areas and the resulting magnetic moments are much smaller because the return-current paths are much closer to the solar-cell sheet currents. The contact pads are prepared with solder fo electrical and mechanical bonding to the cells. The pocketed cover/shield, the solar cells, the printed-wiring layer, an electrical bonding agent, a mechanical-bonding agent, a composite structural front-side face sheet, an aluminum honeycomb core, and a composite back-side face sheet are all assembled, then contact pads are soldered to the cells and the agents are cured in a single lamination process.

  15. On electromagnetic conservation laws

    NASA Astrophysics Data System (ADS)

    Goedecke, G. H.

    2000-04-01

    Subdivision of any charge-current source into N separately conserved sources results in N(N+1)/2 separate conservation laws for each of the interesting electromagnetic quantities, energy, momentum, and angular momentum. The subdivision may be done arbitrarily, so N is also arbitrary. These separate conservation laws are derived and applied to several examples, including the Fourier series representation of any time-dependent source, the derivation of the optical theorem in scattering, the energy balance for a resistor carrying a steady current, and the force on one charged capacitor plate due to the other. A general result is that the Lorentz force exerted by any static source on itself is zero. Other applications are also discussed.

  16. Computational electronics and electromagnetics

    SciTech Connect

    Shang, C. C.

    1997-02-01

    The Computational Electronics and Electromagnetics thrust area at Lawrence Livermore National Laboratory serves as the focal point for engineering R&D activities for developing computer-based design, analysis, and tools for theory. Key representative applications include design of particle accelerator cells and beamline components; engineering analysis and design of high-power components, photonics, and optoelectronics circuit design; EMI susceptibility analysis; and antenna synthesis. The FY-96 technology-base effort focused code development on (1) accelerator design codes; (2) 3-D massively parallel, object-oriented time-domain EM codes; (3) material models; (4) coupling and application of engineering tools for analysis and design of high-power components; (5) 3-D spectral-domain CEM tools; and (6) enhancement of laser drilling codes. Joint efforts with the Power Conversion Technologies thrust area include development of antenna systems for compact, high-performance radar, in addition to novel, compact Marx generators. 18 refs., 25 figs., 1 tab.

  17. Causal electromagnetic interaction equations

    SciTech Connect

    Zinoviev, Yury M.

    2011-02-15

    For the electromagnetic interaction of two particles the relativistic causal quantum mechanics equations are proposed. These equations are solved for the case when the second particle moves freely. The initial wave functions are supposed to be smooth and rapidly decreasing at the infinity. This condition is important for the convergence of the integrals similar to the integrals of quantum electrodynamics. We also consider the singular initial wave functions in the particular case when the second particle mass is equal to zero. The discrete energy spectrum of the first particle wave function is defined by the initial wave function of the free-moving second particle. Choosing the initial wave functions of the free-moving second particle it is possible to obtain a practically arbitrary discrete energy spectrum.

  18. The ALICE Electromagnetic Calorimeter

    SciTech Connect

    Gadrat, S.

    2010-06-01

    ALICE (A Large Ion Collider Experiment) is the only LHC experiment at CERN fully dedicated to the study of the quark and gluon plasma. Driven by the RHIC results on jet quenching, the ALICE collaboration has proposed to extend the capabilities of the ALICE detector for the study of high momentum photons and jets by adding a large acceptance calorimeter. This EMCal (ElectroMagnetic Calorimeter) is designed to provide an unbiased fast high-p{sub T} trigger and to measure the neutral energy of jets and photons up to 200 GeV. Four over ten supermodules of the calorimeter have been installed and commissioned at CERN in 2009 which represents 40% of the full acceptance.

  19. Electromagnetic modeling in accelerator designs

    SciTech Connect

    Cooper, R.K.; Chan, K.C.D.

    1990-01-01

    Through the years, electromagnetic modeling using computers has proved to be a cost-effective tool for accelerator designs. Traditionally, electromagnetic modeling of accelerators has been limited to resonator and magnet designs in two dimensions. In recent years with the availability of powerful computers, electromagnetic modeling of accelerators has advanced significantly. Through the above conferences, it is apparent that breakthroughs have been made during the last decade in two important areas: three-dimensional modeling and time-domain simulation. Success in both these areas have been made possible by the increasing size and speed of computers. In this paper, the advances in these two areas will be described.

  20. SOLAR NANTENNA ELECTROMAGNETIC COLLECTORS

    SciTech Connect

    Steven D. Novack; Dale K. Kotter; Dennis Slafer; Patrick Pinhero

    2008-08-01

    This research explores a new efficient approach for producing electricity from the abundant energy of the sun. A nanoantenna electromagnetic collector (NEC) has been designed, prototyped, and tested. Proof of concept has been validated. The device targets mid-infrared wavelengths where conventional photovoltaic (PV) solar cells do not respond but is abundant in solar energy. The initial concept of designing NEC antennas was based on scaling of radio frequency antenna theory. This approach has proven unsuccessful by many due to not fully understanding and accounting for the optical behavior of materials in the THz region. Also until recent years the nanofabrication methods were not available to fabricate the optical antenna elements. We have addressed and overcome both technology barriers. Several factors were critical in successful implementation of NEC including: 1) frequency-dependent modeling of antenna elements, 2) selection of materials with proper THz properties and 3) novel manufacturing methods that enable economical large-scale manufacturing. The work represents an important step toward the ultimate realization of a low-cost device that will collect as well as convert this radiation into electricity, which will lead to a wide spectrum, high conversion efficiency, and low cost solution to complement conventional PVs.

  1. Pulsed electromagnetic gas acceleration

    NASA Technical Reports Server (NTRS)

    Jahn, R. G.; Vonjaskowsky, W. F.; Clark, K. E.

    1974-01-01

    Detailed measurements of the axial velocity profile and electromagnetic structure of a high power, quasi-steady MPD discharge are used to formulate a gasdynamic model of the acceleration process. Conceptually dividing the accelerated plasma into an inner flow and an outer flow, it is found that more than two-thirds of the total power in the plasma is deposited in the inner flow, accelerating it to an exhaust velocity of 12.5 km/sec. The outer flow, which is accelerated to a velocity of only 6.2 km/sec, appears to provide a current conduction path between the inner flow and the anode. Related cathode studies have shown that the critical current for the onset of terminal voltage fluctuations, which was recently shown to be a function of the cathode area, appears to reach an asymptote for cathodes of very large surface area. Detailed floating potential measurements show that the fluctuations are confined to the vicinity of the cathode and hence reflect a cathode emission process rather than a fundamental limit on MPD performance.

  2. Electromagnetism of Bacterial Growth

    NASA Astrophysics Data System (ADS)

    Ainiwaer, Ailiyasi

    2011-10-01

    There has been increasing concern from the public about personal health due to the significant rise in the daily use of electrical devices such as cell phones, radios, computers, GPS, video games and television. All of these devices create electromagnetic (EM) fields, which are simply magnetic and electric fields surrounding the appliances that simultaneously affect the human bio-system. Although these can affect the human system, obstacles can easily shield or weaken the electrical fields; however, magnetic fields cannot be weakened and can pass through walls, human bodies and most other objects. The present study was conducted to examine the possible effects of bacteria when exposed to magnetic fields. The results indicate that a strong causal relationship is not clear, since different magnetic fields affect the bacteria differently, with some causing an increase in bacterial cells, and others causing a decrease in the same cells. This phenomenon has yet to be explained, but the current study attempts to offer a mathematical explanation for this occurrence. The researchers added cultures to the magnetic fields to examine any effects to ion transportation. Researchers discovered ions such as potassium and sodium are affected by the magnetic field. A formula is presented in the analysis section to explain this effect.

  3. Electromagnetically driven peristaltic pump

    DOEpatents

    Marshall, Douglas W.

    2000-01-01

    An electromagnetic peristaltic pump apparatus may comprise a main body section having an inlet end and an outlet end and a flexible membrane which divides the main body section into a first cavity and a second cavity. The first cavity is in fluid communication with the inlet and outlet ends of the main body section. The second cavity is not in fluid communication with the first cavity and contains an electrically conductive fluid. The second cavity includes a plurality of electrodes which are positioned within the second cavity generally adjacent the flexible membrane. A magnetic field generator produces a magnetic field having a plurality of flux lines at least some of which are contained within the second cavity of the main body section and which are oriented generally parallel to a flow direction in which a material flows between the inlet and outlet ends of the main body section. A control system selectively places a voltage potential across selected ones of the plurality of electrodes to deflect the flexible membrane in a wave-like manner to move material contained in the first cavity between the inlet and outlet ends of the main body section.

  4. Electromagnetic Interference on Pacemakers

    PubMed Central

    Erdogan, Okan

    2002-01-01

    External sources, either within or outside the hospital environment, may interfere with the appropriate function of pacemakers which are being implanted all around the world in current medical practice. The patient and the physician who is responsible for follow-up of the pacing systems may be confronted with some specific problems regarding the various types of electromagnetic interference (EMI). To avoid these unwanted EMI effects one must be aware of this potential problem and need to take some precautions. The effects of EMI on pacemaker function and precautions to overcome some specific problems were discussed in this review article. There are many sources of EMI interacting with pacemakers. Magnetic resonance imaging creates real problem and should be avoided in pacemaker patients. Cellular phones might be responsible for EMI when they were held on the same side with the pacemaker. Otherwise they don't cause any specific type of interaction with pacemakers. Sale security systems are not a problem if one walks through it without lingering in or near it. Patients having unipolar pacemaker systems are prone to develop EMI because of pectoral muscle artifacts during vigorous active physical exercise. PMID:17006562

  5. Earthquake prediction with electromagnetic phenomena

    NASA Astrophysics Data System (ADS)

    Hayakawa, Masashi

    2016-02-01

    Short-term earthquake (EQ) prediction is defined as prospective prediction with the time scale of about one week, which is considered to be one of the most important and urgent topics for the human beings. If this short-term prediction is realized, casualty will be drastically reduced. Unlike the conventional seismic measurement, we proposed the use of electromagnetic phenomena as precursors to EQs in the prediction, and an extensive amount of progress has been achieved in the field of seismo-electromagnetics during the last two decades. This paper deals with the review on this short-term EQ prediction, including the impossibility myth of EQs prediction by seismometers, the reason why we are interested in electromagnetics, the history of seismo-electromagnetics, the ionospheric perturbation as the most promising candidate of EQ prediction, then the future of EQ predictology from two standpoints of a practical science and a pure science, and finally a brief summary.

  6. Electromagnetic Interference In New Aircraft

    NASA Technical Reports Server (NTRS)

    Larsen, William E.

    1991-01-01

    Report reviews plans to develop tests and standards to ensure that digital avionics systems in new civil aircraft immune to electromagnetic interference (EMI). Updated standards reflect more severe environment and vulnerabilities of modern avionics.

  7. Multidimensional analysis of electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Santolik, O.; Pisa, D.; Soucek, J.

    2015-10-01

    Multidimensional measurements of electromagnetic fields in space plasmas can be processed by various methods to obtain information about the polarization and propagation properties of the corresponding wave modes. New developments are planned in the frame of EPN-2020-RI.

  8. Measurement of electromagnetic energy flow

    NASA Astrophysics Data System (ADS)

    Mishchenko, M. I.

    2012-12-01

    The measurement of electromagnetic energy flow is an integral part of solving radiation-budget and optical-characterization problems. It is therefore very important to understand clearly what specific measurement is afforded by an optical instrument and how to model this measurement theoretically. We will not discuss technical and technological issues related to the development of sensitive and efficient detectors of light. Instead, the discussion will focus on the precise definitions of general measurement principles and their specific practical implications in the framework of electromagnetic scattering by particles and particle groups. We will discuss in succession measurements with direction-insensitive detectors, monodirectional well-collimated, and panoramic well-collimated radiometers. Special attention will be paid to the electromagnetic response of a well-collimated radiometer to polychromatic light. We will see, in particular, that although the main characteristic of electromagnetic energy flow is the Poynting vector, the actual measurement of this quantity is possible only in very special cases.

  9. Conical electromagnetic radiation flux concentrator

    NASA Technical Reports Server (NTRS)

    Miller, E. R.

    1972-01-01

    Concentrator provides method of concentrating a beam of electromagnetic radiation into a smaller beam, presenting a higher flux density. Smaller beam may be made larger by sending radiation through the device in the reverse direction.

  10. 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)

  11. Self-dual electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Chubykalo, Andrew E.; Espinoza, Augusto; Kosyakov, B. P.

    2010-08-01

    We demonstrate the utility of self-dual fields in electrodynamics. Stable configurations of free electromagnetic fields can be represented as superpositions of standing waves, each possessing zero Poynting vector and zero orbital angular momentum. The standing waves are themselves superpositions of self-dual and anti-self-dual solutions. The idea of self-duality provides additional insights into the geometrical and spectral properties of stable electromagnetic configurations, such as those responsible for the formation of ball lightning.

  12. Megawatt Electromagnetic Plasma Propulsion

    NASA Technical Reports Server (NTRS)

    Gilland, James; Lapointe, Michael; Mikellides, Pavlos

    2003-01-01

    The NASA Glenn Research Center program in megawatt level electric propulsion is centered on electromagnetic acceleration of quasi-neutral plasmas. Specific concepts currently being examined are the Magnetoplasmadynamic (MPD) thruster and the Pulsed Inductive Thruster (PIT). In the case of the MPD thruster, a multifaceted approach of experiments, computational modeling, and systems-level models of self field MPD thrusters is underway. The MPD thruster experimental research consists of a 1-10 MWe, 2 ms pulse-forming-network, a vacuum chamber with two 32 diffusion pumps, and voltage, current, mass flow rate, and thrust stand diagnostics. Current focus is on obtaining repeatable thrust measurements of a Princeton Benchmark type self field thruster operating at 0.5-1 gls of argon. Operation with hydrogen is the ultimate goal to realize the increased efficiency anticipated using the lighter gas. Computational modeling is done using the MACH2 MHD code, which can include real gas effects for propellants of interest to MPD operation. The MACH2 code has been benchmarked against other MPD thruster data, and has been used to create a point design for a 3000 second specific impulse (Isp) MPD thruster. This design is awaiting testing in the experimental facility. For the PIT, a computational investigation using MACH2 has been initiated, with experiments awaiting further funding. Although the calculated results have been found to be sensitive to the initial ionization assumptions, recent results have agreed well with experimental data. Finally, a systems level self-field MPD thruster model has been developed that allows for a mission planner or system designer to input Isp and power level into the model equations and obtain values for efficiency, mass flow rate, and input current and voltage. This model emphasizes algebraic simplicity to allow its incorporation into larger trajectory or system optimization codes. The systems level approach will be extended to the pulsed inductive thruster and other electrodeless thrusters at a future date.

  13. Resolution in Electromagnetic Prospecting

    NASA Astrophysics Data System (ADS)

    Aldridge, D. F.; Bartel, L. C.; Knox, H. A.; Schramm, K. A.

    2014-12-01

    Low-frequency electromagnetic (EM) signals are commonly used in geophysical exploration of the shallow subsurface. Sensitivity to conductivity implies they are particularly useful for inferring fluid content of porous media. However, low-frequency EM wavefields are diffusive, and have significantly larger wavelengths compared to seismic signals of equal frequency. The wavelength of a 30 Hz sinusoid propagating with seismic velocity 3000 m/s is 100 m, whereas an analogous EM signal diffusing through a conductive body of 0.1 S/m (clayey shale) has wavelength 1825 m. The larger wavelength has implications for resolution of the EM prospecting method. We are investigating resolving power of the EM method via theoretical and numerical experiments. Normal incidence plane wave reflection/transmission by a thin geologic bed is amenable to analytic solution. Responses are calculated for beds that are conductive or resistive relative to the host rock. Preliminary results indicate the classic seismic resolution/detection limit of bed thickness ~1/8 wavelength is not achieved. EM responses for point or line current sources recorded by general acquisition geometries are calculated with a 3D finite-difference algorithm. These exhibit greater variability which may allow inference of bed thickness. We also examine composite responses of two point scatterers with separation when illuminated by an incident EM field. This is analogous to the Rayleigh resolution problem of estimating angular separation between two light sources. The First Born Approximation implies that perturbations in permittivity, permeability, and conductivity have different scattering patterns, which may be indicators of EM medium properties. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  14. Information Security due to Electromagnetic Environments

    NASA Astrophysics Data System (ADS)

    Sekiguchi, Hidenori; Seto, Shinji

    Generally, active electronic devices emit slightly unintentional electromagnetic noise. From long ago, electromagnetic emission levels have been regulated from the aspect of electromagnetic compatibility (EMC). Also, it has been known the electromagnetic emissions have been generated from the ON/OFF of signals in the device. Recently, it becomes a topic of conversation on the information security that the ON/OFF on a desired signal in the device can be reproduced or guessed by receiving the electromagnetic emission. For an example, a display image on a personal computer (PC) can be reconstructed by receiving and analyzing the electromagnetic emission. In sum, this fact makes known information leakage due to electromagnetic emission. “TEMPEST" that has been known as a code name originated in the U. S. Department of Defense is to prevent the information leakage caused by electromagnetic emissions. This paper reports the brief summary of the information security due to electromagnetic emissions from information technology equipments.

  15. High performance electromagnetic simulation tools

    NASA Astrophysics Data System (ADS)

    Gedney, Stephen D.; Whites, Keith W.

    1994-10-01

    Army Research Office Grant #DAAH04-93-G-0453 has supported the purchase of 24 additional compute nodes that were installed in the Intel iPsC/860 hypercube at the Univesity Of Kentucky (UK), rendering a 32-node multiprocessor. This facility has allowed the investigators to explore and extend the boundaries of electromagnetic simulation for important areas of defense concerns including microwave monolithic integrated circuit (MMIC) design/analysis and electromagnetic materials research and development. The iPSC/860 has also provided an ideal platform for MMIC circuit simulations. A number of parallel methods based on direct time-domain solutions of Maxwell's equations have been developed on the iPSC/860, including a parallel finite-difference time-domain (FDTD) algorithm, and a parallel planar generalized Yee-algorithm (PGY). The iPSC/860 has also provided an ideal platform on which to develop a 'virtual laboratory' to numerically analyze, scientifically study and develop new types of materials with beneficial electromagnetic properties. These materials simulations are capable of assembling hundreds of microscopic inclusions from which an electromagnetic full-wave solution will be obtained in toto. This powerful simulation tool has enabled research of the full-wave analysis of complex multicomponent MMIC devices and the electromagnetic properties of many types of materials to be performed numerically rather than strictly in the laboratory.

  16. Perturbations in electromagnetic dark energy

    SciTech Connect

    Jiménez, Jose Beltrán; Maroto, Antonio L.; Koivisto, Tomi S.; Mota, David F. E-mail: T.Koivisto@thphys.uni-heidelberg.de E-mail: d.f.mota@astro.uio.no

    2009-10-01

    It has been recently proposed that the presence of a temporal electromagnetic field on cosmological scales could explain the phase of accelerated expansion that the universe is currently undergoing. The field contributes as a cosmological constant and therefore, the homogeneous cosmology produced by such a model is exactly the same as that of ΛCDM. However, unlike a cosmological constant term, electromagnetic fields can acquire perturbations which in principle could affect CMB anisotropies and structure formation. In this work, we study the evolution of inhomogeneous scalar perturbations in this model. We show that provided the initial electromagnetic fluctuations generated during inflation are small, the model is perfectly compatible with both CMB and large scale structure observations at the same level of accuracy as ΛCDM.

  17. Electromagnetic fields and public health.

    PubMed Central

    Aldrich, T E; Easterly, C E

    1987-01-01

    A review of the literature is provided for the topic of health-related research and power frequency electromagnetic fields. Minimal evidence for concern is present on the basis of animal and plant research. General observation would accord with the implication that there is no single and manifest health effect as the result of exposure to these fields. There are persistent indications, however, that these fields have biologic activity, and consequently, there may be a deleterious component to their action, possibly in the presence of other factors. Power frequency electromagnetic field exposures are essentially ubiquitous in modern society, and their implications in the larger perspective of public health are unclear at this time. Electromagnetic fields represent a methodological obstacle for epidemiologic studies and a quandary for risk assessment; there is need for more data. PMID:3319560

  18. Un-renormalized classical electromagnetism

    SciTech Connect

    Ibison, Michael . E-mail: ibison@earthtech.org

    2006-02-15

    This paper follows in the tradition of direct-action versions of electromagnetism having the aim of avoiding a balance of infinities wherein a mechanical mass offsets an infinite electromagnetic mass so as to arrive at a finite observed value. However, the direct-action approach ultimately failed in that respect because its initial exclusion of self-action was later found to be untenable in the relativistic domain. Pursing the same end, this paper examines instead a version of electromagnetism wherein mechanical action is excluded and self-action is retained. It is shown that the resulting theory is effectively interacting due to the presence of infinite forces. A vehicle for the investigation is a pair of classical point charges in a positronium-like arrangement for which the orbits are found to be self-sustaining and naturally quantized.

  19. Electromagnetic structure of light nuclei

    NASA Astrophysics Data System (ADS)

    Pastore, Saori

    2015-10-01

    I present a number of ab initio Quantum Monte Carlo calculations of electromagnetic observables for A <= 10 nuclei, which account for two-body effects due to the coupling of external photons with pairs of interacting nucleons. Nuclear wave functions are generated from a nuclear Hamiltonian with the Argonne v18 two-nucleon and Illinois-7 three-nucleon potentials, while chiral effective field theory is utilized to construct the two-body electromagnetic current operators. Emphasis is on recent calculations of magnetic radii and Zemach moments of light nuclei.

  20. Electromagnetic computations for fusion devices

    SciTech Connect

    Turner, L.R.

    1989-09-01

    Among the difficulties in making nuclear fusion a useful energy source, two important ones are producing the magnetic fields needed to drive and confine the plasma, and controlling the eddy currents induced in electrically conducting components by changing fields. All over the world, researchers are developing electromagnetic codes and employing them to compute electromagnetic effects. Ferromagnetic components of a fusion reactor introduce field distortions. Eddy currents are induced in the vacuum vessel, blanket and other torus components of a tokamak when the plasma current disrupts. These eddy currents lead to large forces, and 3-D codes are being developed to study the currents and forces. 35 refs., 6 figs.

  1. Physiologic regulation in electromagnetic fields.

    PubMed

    Michaelson, S M

    1982-01-01

    Electromagnetic fields have been demonstrated to elicit thermoregulatory responses, neuroendocrine, neurochemical modulations, and behavioral reactions. These physiologic regulatory processes are exquisitely tuned, interrelated functions that constitute sensitive indicators of organismic responses to radiofrequency energy absorption (the radiofrequency portion of the electromagnetic spectrum includes as one part microwaves). Assessment of the integration and correlation of these functions relative to the thermal inputs and homeokinetic reactions of the individual subjected to radiofrequency energy should permit differentiation between potential hazards that might compromise the individual's ability to maintain normal physiologic function and effects that are compensated by physiologic redundancy. PMID:7082396

  2. Physiologic regulation in electromagnetic fields

    SciTech Connect

    Michaelson, S.M.

    1982-01-01

    Electromagnetic fields have been demonstrated to elicit thermoregulatory responses, neuroendocrine, neurochemical modulations, and behavioral reactions. These physiologic regulatory processes are exquisitely tuned, interrelated functions that constitute sensitive indicators of organismic responses to radiofrequency energy absorption (the radiofrequency portion of the electromagnetic spectrum includes as one part microwaves). Assessment of the integration and correlation of these functions relative to the thermal inputs and homeokinetic reactions of the individual subjected to radiofrequency energy should permit differentiation between potential hazards that might compromise the individual's ability to maintain normal physiologic function and effects that are compensated by physiologic redundancy.

  3. Electromagnetic Gun With Commutated Coils

    NASA Technical Reports Server (NTRS)

    Elliott, David G.

    1991-01-01

    Proposed electromagnetic gun includes electromagnet coil, turns of which commutated in sequence along barrel. Electrical current fed to two armatures by brushes sliding on bus bars in barrel. Interaction between armature currents and magnetic field from coil produces force accelerating armature, which in turn, pushes on projectile. Commutation scheme chosen so magnetic field approximately coincides and moves with cylindrical region defined by armatures. Scheme has disadvantage of complexity, but in return, enables designer to increase driving magnetic field without increasing armature current. Attainable muzzle velocity increased substantially.

  4. Electromagnetic effects on planetary rings

    SciTech Connect

    Morfill, G.E.

    1983-01-01

    The role of electromagnetic effects in planetary rings is reviewed. The rings consist of a collection of solid particles with a size spectrum ranging from submicron to 10's of meters (at least in the case of Saturn's rings). Due to the interaction with the ambient plasma, and solar UV radiation, the particles carry electrical charges. Interactions of particles with the planetary electromagnetic field, both singly and collectively, are described, as well as the reactions and influence on plasma transients. The latter leads to a theory for the formation of Saturn's spokes, which is briefly reviewed.

  5. Bathymetry, electromagnetic streamlines and the marine controlled source electromagnetic method

    NASA Astrophysics Data System (ADS)

    Pethick, Andrew 12Harris, Brett

    2014-07-01

    Seafloor topography must influence the strength and direction of electromagnetic fields generated during deep ocean controlled source electromagnetic surveying. Neither mathematical equation nor rules of thumb provide a clear perspective of how changes in water column thickness alters electromagnetic fields that engulf hundreds of cubic kilometres of air, ocean, host and reservoir. We use streamline visualisation to provide a generalised representation of how electromagnetic fields propagate into a 2D geo-electrical setting that includes strong bathymetry. Of particular interest are: (i)' dead zones' where electric fields at the ocean floor are demonstrated to be weak and (ii) the 'airwave' that appears in the electric field streamlines as circulating vortices with a shape that is clearly influenced by changes in ocean depth. Our analysis of the distribution of electric fields for deep and shallow water examples alludes to potential benefits from placement of receivers and/or transmitters higher in the water column as is the case for towed receiver geometries. Real-time streamline representation probably holds the most value at the survey planning stage, especially for shallow water marine EM surveys where ocean bottom topography is likely to be consequential.

  6. Versatile Support For Electromagnetic-Test Model

    NASA Technical Reports Server (NTRS)

    Wood, Richard M.; Ford, Eddie D.

    1994-01-01

    Supporting apparatus holds model for measurements of electromagnetic properties. Includes rigid swept strut, on end of which model oriented over range of angles. Designed to interfere minimally with electromagnetic measurements.

  7. Electromagnetic pulses bone healing booster

    NASA Astrophysics Data System (ADS)

    Sintea, S. R.; Pomazan, V. M.; Bica, D.; Grebenisan, D.; Bordea, N.

    2015-11-01

    Posttraumatic bone restoration triggered by the need to assist and stimulate compensatory bone growth in periodontal condition. Recent studies state that specific electromagnetic stimulation can boost the bone restoration, reaching up to 30% decrease in recovery time. Based on the existing data on the electromagnetic parameters, a digital electronic device is proposed for intra oral mounting and bone restoration stimulation in periodontal condition. The electrical signal is applied to an inductive mark that will create and impregnate magnetic field in diseased tissue. The device also monitors the status of the electromagnetic field. Controlled wave forms and pulse frequency signal at programmable intervals are obtained with optimized number of components and miniaturized using surface mounting devices (SMD) circuits and surface mounting technology (SMT), with enhanced protection against abnormal current growth, given the intra-oral environment. The system is powered by an autonomous power supply (battery), to limit the problems caused by powering medical equipment from the main power supply. Currently the device is used in clinical testing, in cycles of six up to twelve months. Basic principles for the electrical scheme and algorithms for pulse generation, pulse control, electromagnetic field control and automation of current monitoring are presented, together with the friendly user interface, suitable for medical data and patient monitoring.

  8. Proposed electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L.

    1973-01-01

    Device converts wave energy into electric power through array of insulated absorber elements responsive to field of impinging electromagnetic radiation. Device could also serve as solar energy converter that is potentially less expensive and fragile than solar cells, yet substantially more efficient.

  9. Coupling Electromagnetism to Global Charge

    NASA Astrophysics Data System (ADS)

    Guendelman, E. I.

    2013-12-01

    It is shown that an alternative to the standard scalar quantum electrodynamics (QED) is possible. In this new version, there is only global gauge invariance as far as the charged scalar fields are concerned, although local gauge invariance is kept for the electromagnetic field. The electromagnetic coupling has the form jμ(Aμ +∂μB) where B is an auxiliary field and the current jμ is Aμ independent, so that no "sea gull terms" are introduced. As a consequence of the absence of sea gulls, it is seen that no Klein paradox appears in the presence of a strong square well potential. In a model of this kind, spontaneous breaking of symmetry does not lead to photon mass generation, instead the Goldstone boson becomes a massless source for the electromagnetic field. When spontaneous symmetry breaking takes place infrared questions concerning the theory and generalizations to global vector QED are discussed. In this framework, Q-Balls and other nontopological solitons that owe their existence to a global U(1) symmetry can be coupled to electromagnetism and could represent multiply charged particles now in search in the large hadron collider (LHC). Furthermore, we give an example where an "Emergent" Global Scalar QED can appear from an axion-photon system in an external magnetic field. Finally, formulations of Global Scalar QED that allow perturbative expansions without sea gulls are developed.

  10. Explanations, Education, and Electromagnetic Fields.

    ERIC Educational Resources Information Center

    Friedman, Sharon M.

    Explaining complex scientific and environmental subjects in the mass media is difficult to do, particularly under such constraints as short deadlines and lack of space or time. When a scientific controversy and human health risk are involved, this becomes an even harder task to accomplish. The subject of electromagnetic fields (EMF) involves…

  11. Electromagnetic Levitation of a Disc

    ERIC Educational Resources Information Center

    Valle, R.; Neves, F.; de Andrade, R., Jr.; Stephan, R. M.

    2012-01-01

    This paper presents a teaching experiment that explores the levitation of a disc of ferromagnetic material in the presence of the magnetic field produced by a single electromagnet. In comparison to the classical experiment of the levitation of a sphere, the main advantage of the proposed laboratory bench is that the uniform magnetic field

  12. The courts and electromagnetic fields

    SciTech Connect

    Freeman, M. )

    1990-07-19

    This article examines the recent development in eminent domain cases involving power transmission line rights of way, the issue of fear of the mythical buyer. The author feels that the fear of electrocution or of the possible cancer-inducing effects of electromagnetic fields is greatly influencing court decisions in these cases. The results could be more expensive rights of way acquisition by utilities.

  13. Electromagnetic Levitation of a Disc

    ERIC Educational Resources Information Center

    Valle, R.; Neves, F.; de Andrade, R., Jr.; Stephan, R. M.

    2012-01-01

    This paper presents a teaching experiment that explores the levitation of a disc of ferromagnetic material in the presence of the magnetic field produced by a single electromagnet. In comparison to the classical experiment of the levitation of a sphere, the main advantage of the proposed laboratory bench is that the uniform magnetic field…

  14. Electromagnetic effects on geodesic acoustic modes

    NASA Astrophysics Data System (ADS)

    Bashir, M. F.; Smolyakov, A. I.; Elfimov, A. G.; Melnikov, A. V.; Murtaza, G.

    2014-08-01

    By using the full electromagnetic drift kinetic equations for electrons and ions, the general dispersion relation for geodesic acoustic modes (GAMs) is derived incorporating the electromagnetic effects. It is shown that m = 1 harmonic of the GAM mode has a finite electromagnetic component. The electromagnetic corrections appear for finite values of the radial wave numbers and modify the GAM frequency. The effects of plasma pressure βe, the safety factor q, and the temperature ratio τ on GAM dispersion are analyzed.

  15. Electromagnetic design considerations for fast acting controllers

    SciTech Connect

    Woodford, D.A.

    1996-07-01

    Electromagnetic design considerations for fast acting controllers in a power system is introduced and defined. A distinction is made in relation to the more commonly understood system control design necessary for damping electromechanical oscillations using stability programs and eigenanalysis. Electromagnetic eigenanalysis tools have limited availability and are consequently rarely used. Electromagnetic transients programs (emtp) on the other hand are widely used and a procedure for undertaking electromagnetic control design of fast acting controllers in a power system using emtp is presented.

  16. Some Student Conceptions of Electromagnetic Induction

    ERIC Educational Resources Information Center

    Thong, Wai Meng; Gunstone, Richard

    2008-01-01

    Introductory electromagnetism is a central part of undergraduate physics. Although there has been some research into student conceptions of electromagnetism, studies have been sparse and separated. This study sought to explore second year physics students' conceptions of electromagnetism, to investigate to what extent the results from the present…

  17. Some Student Conceptions of Electromagnetic Induction

    ERIC Educational Resources Information Center

    Thong, Wai Meng; Gunstone, Richard

    2008-01-01

    Introductory electromagnetism is a central part of undergraduate physics. Although there has been some research into student conceptions of electromagnetism, studies have been sparse and separated. This study sought to explore second year physics students' conceptions of electromagnetism, to investigate to what extent the results from the present

  18. Strong permanent magnet-assisted electromagnetic undulator

    DOEpatents

    Halbach, Klaus

    1988-01-01

    This invention discloses an improved undulator comprising a plurality of electromagnet poles located along opposite sides of a particle beam axis with alternate north and south poles on each side of the beam to cause the beam to wiggle or undulate as it travels generally along the beam axis and permanent magnets spaced adjacent the electromagnetic poles on each side of the axis of said particle beam in an orientation sufficient to reduce the saturation of the electromagnet poles whereby the field strength of the electromagnet poles can be increased beyond the normal saturation levels of the electromagnetic poles.

  19. Time domain electromagnetic metal detectors

    SciTech Connect

    Hoekstra, P.

    1996-04-01

    This presentation focuses on illustrating by case histories the range of applications and limitations of time domain electromagnetic (TDEM) systems for buried metal detection. Advantages claimed for TDEM metal detectors are: independent of instrument response (Geonics EM61) to surrounding soil and rock type; simple anomaly shape; mitigation of interference by ambient electromagnetic noise; and responsive to both ferrous and non-ferrous metallic targets. The data in all case histories to be presented were acquired with the Geonics EM61 TDEM system. Case histories are a test bed site on Molokai, Hawaii; Fort Monroe, Virginia; and USDOE, Rocky Flats Plant. The present limitations of this technology are: discrimination capabilities in terms of type of ordnance, and depth of burial is limited, and ability of resolving targets with small metallic ambient needs to be improved.

  20. Electromagnetic transduction of ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Passarelli, Frank; Alers, George; Alers, Ron

    2012-05-01

    Excitation and detection of ultrasonic vibrations without physical contact has proven to be of great commercial value. First used to excite the resonant vibration of bar shaped laboratory specimens in the 1930's, it was Bruce Thompson's contributions in 1973-5 that launched their practical application to a wide range of difficult NDE problems. As a fresh PhD, he championed the use of mathematical models for the electromagnetic transduction process in order to guide the design and construction of practical transducers. His early papers presented both theoretical and experimental results that exposed the wide range of wave types that could be generated along with the environmental conditions that could be overcome. Several laboratories around the world established research programs to apply the electromagnetic transducer (EMAT) to specific NDE problems. This paper will summarize those applications made by the authors.

  1. Falling Magnets and Electromagnetic Braking

    NASA Astrophysics Data System (ADS)

    Culbreath, Christopher; Palffy-Muhoray, Peter

    2009-03-01

    The slow fall of a rare earth magnet through a copper pipe is a striking example of electromagnetic braking; this remarkable phenomenon has been the subject of a number of scientific paper s [1, 2]. In a pipe having radius R and wall thickness D, the terminal velocity of the falling magnet is proportional to (R̂4)/D. It is interesting to ask what happens in the limit as D becomes very large. We report our experimental observations and theoretical predictions of the dependence of the terminal velocity on pipe radius R for large D. [1] Y. Levin, F.L. da Silveira, and F.B. Rizzato, ``Electromagnetic braking: A simple quantitative model''. American Journal of Physics, 74(9): p. 815-817 (2006). [2] J.A. Pelesko, M. Cesky, and S. Huertas, Lenz's law and dimensional analysis. American Journal of Physics, 3(1): p. 37-39. 2005.

  2. Transient electromagnetic interference in substations

    SciTech Connect

    Wiggins, C.M.; Thomas, D.E.; Nickel, F.S.; Salas, T.M. ); Wright, S.E. )

    1994-10-01

    Electromagnetic interference levels on sensitive electronic equipment are quantified experimentally and theoretically in air and gas insulated substations of different voltages. Measurement techniques for recording interference voltages and currents and electric and magnetic fields are reviewed and actual interference data are summarized. Conducted and radiated interference coupling mechanisms and levels in substation control wiring are described using both measurement results and electromagnetic models validated against measurements. The nominal maximum field and control wire interference levels expected in the switchyard and inside the control house from switching operations, faults, and an average lightning strike are estimated using high frequency transient coupling models. Comparisons with standards are made and recommendations given concerning equipment shielding and surge protection.

  3. Electromagnetic Activation of Capillary Switches

    NASA Astrophysics Data System (ADS)

    Malouin, Bernie; Dayal, Rohan; Parsa, Leila; Hirsa, Amir

    2008-11-01

    By designing coupled droplet pairs with the appropriate length scale to promote surface tension as the dominant force, one can create bi-stable capillary switches. This bi-stability can be triggered by pressure pulses, surface chemistry, electroosmosis, or body forces. To exploit the latter, we designed a capillary switch with electromagnetic activation. The resulting setup consists of a sub-millimeter tube, overfilled with a ferrofluid, surrounded by a wire coil to generate a magnetic field. Evidence of this capillary switching will be presented along with some theoretical basis in fluid- and electro-dynamics. The approach may also be used to investigate other transport phenomena in electromagnetically-coupled microfluidic systems, including the relative effects of translational motion of the ferrofluid (both particles and solvent molecules) versus the rotational effects of the individual magnetic grains. These individually addressable capillary switches offer intriguing applications including high-speed adaptive optics, actuators at the microscale, and possible PCB integration.

  4. Laminated electromagnetic pump stator core

    DOEpatents

    Fanning, Alan W.

    1995-01-01

    A stator core for an electromagnetic pump includes a plurality of circumferentially abutting tapered laminations extending radially outwardly from a centerline axis to collectively define a radially inner bore and a radially outer circumference. Each of the laminations includes radially inner and outer edges and has a thickness increasing from the inner edge toward the outer edge to provide a substantially continuous path adjacent the circumference.

  5. Laminated electromagnetic pump stator core

    DOEpatents

    Fanning, A.W.

    1995-08-08

    A stator core for an electromagnetic pump includes a plurality of circumferentially abutting tapered laminations extending radially outwardly from a centerline axis to collectively define a radially inner bore and a radially outer circumference. Each of the laminations includes radially inner and outer edges and has a thickness increasing from the inner edge toward the outer edge to provide a substantially continuous path adjacent the circumference. This pump is used in nuclear fission reactors. 19 figs.

  6. electromagnetics, eddy current, computer codes

    Energy Science and Technology Software Center (ESTSC)

    2002-03-12

    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.

  7. Electromagnetically controlled multiferroic thermal diode

    NASA Astrophysics Data System (ADS)

    Chotorlishvili, L.; Etesami, S. R.; Berakdar, J.; Khomeriki, R.; Ren, Jie

    2015-10-01

    We propose an electromagnetically tunable thermal diode based on a two-phase multiferroic composite. Analytical and full numerical calculations for a prototypical heterojunction composed of iron on barium titanate in the tetragonal phase demonstrate a strong heat rectification effect that can be controlled externally by a moderate electric field. This finding is important for thermally based information processing and sensing and can also be integrated in (spin) electronic circuits for heat management and recycling.

  8. Electromagnetic Calorimeter for HADES Experiment

    NASA Astrophysics Data System (ADS)

    Rodríguez-Ramos, P.; Chlad, L.; Epple, E.; Fabbietti, L.; Galatyuk, T.; Golubeva, M.; Guber, F.; Hlaváč, S.; Ivashkin, A.; Kajetanowic, M.; Kardan, B.; Koenig, W.; Korcyl, G.; Kugler, A.; Lapidus, K.; Linev, S.; Lisowski, E.; Neiser, A.; Ott, O.; Otte, O.; Pethukov, O.; Pietraszko, J.; Reshetin, A.; Rost, A.; Salabura, P.; Sobolev, Y. G.; Svoboda, O.; Thomas, A.; Tlusty, P.; Traxler, M.

    2014-11-01

    Electromagnetic calorimeter (ECAL) is being developed to complement dilepton spectrometer HADES. ECAL will enable the HADES@FAIR experiment to measure data on neutral meson production in heavy ion collisions at the energy range of 2-10 AGeV on the beam of future accelerator SIS100@FAIR. We will report results of the last beam test with quasi-monoenergetic photons carried out in MAMI facility at Johannes Gutenberg Universität Mainz.

  9. Pulsed power for electromagnetic launching

    SciTech Connect

    Cowan, M

    1980-12-01

    There are system advantages to producing power for electromagnetic propulsion by real-time generation rather than by a sequence of generation-storage-switching. The best type of generator for this purpose is the flux compression generator. Different types of flux compression generator which have been developed at Sandia National Laboratories are reviewed and their applications to electric launching are discussed. New experimental facilities for producing more powerful generators are described and cost comparisons are made.

  10. Pulsed power for electromagnetic launching

    NASA Astrophysics Data System (ADS)

    Cowan, M.

    1980-12-01

    There are system advantages to producing power for electromagnetic propulsion by real-time generation rather than by a sequence of generation-storage-switching. The best type of generator for this purpose is the flux compression generator which have been developed at Sandia National Laboratories are reviewed and their applications to electric launching are discussed. New experimental facilities for producing more powerful generators are described and cost comparisons are made.

  11. Pulsed power for electromagnetic launching

    NASA Astrophysics Data System (ADS)

    Cowan, M.

    1982-01-01

    There are system advantages to producing power for electromagnetic propulsion by real time generation rather than by a sequence of generation-storage-switching. The best type of generator for this purpose is the flux compression generator. Different types of flux compression generator which have been developed at Sandia National Laboratories are reviewed and their applications to electric launching are discussed. New experimental facilities for producing more powerful generators are described and cost comparisons are made.

  12. Electromagnetically Induced Quantum Holographic Imaging

    NASA Astrophysics Data System (ADS)

    Qiu, Tian-Hui; Xie, Min; Ma, Hong-Yang; Zheng, Chun-Hong; Chen, Li-Bo

    2016-05-01

    We study the quantum holographic imaging of one-dimensional electromagnetically induced grating created by a strong standing wave in an atomic medium. Entangled photon pairs, generated in a spontaneous parametric down-conversion process, are employed as the imaging light to realize coincidence recording. By theoretical analysis and numerical simulation, we find that both the amplitude and phase information of the object can be imaged with the characteristic of imaging nonlocally and of arbitrarily controllable image variation in size.

  13. Electromagnetic separation of actinide isotopes

    NASA Astrophysics Data System (ADS)

    Abramychev, S. M.; Balashov, N. V.; Vesnovskii, S. P.; Vjachin, V. N.; Lapin, V. G.; Nikitin, E. A.; Polynov, V. N.

    1992-08-01

    This report describes the design and technical characteristics of the electromagnetic mass-separator S-2 VNIIEF employed in the production of highly enriched isotopes of heavy actinide elements with a small relative difference of mass numbers. The mass-separator S-2 provides highly enriched isotopes in amounts adequate for nuclear physics and applied investigations. The technological procedure is presented, as well as the operational results over many years in the production of highly enriched isotopes of uranium, plutonium, americium and curium.

  14. Shielding effectiveness against electromagnetic interference

    SciTech Connect

    Googe, J.M.; Hess, R.A.

    1987-10-01

    The use of metal-filled and metal-coated plastics and other modified dielectric materials to replace metals for enclosures has created a need to test these materials for their electromagnetic interference (EMI) shielding effectiveness (SE). Shielding effectiveness involves a variety of electromagnetic environments, and useful data can be obtained from tests that carefully limit the environment to that of a plane wave. Such an environment can be created in a circular or rectangular transmission line. Two such transmission line test fixtures, which hold samples of the material to be tested, have been developed. The fixtures described in this report are the National Bureau of Standards (NBS) coaxial transverse electromagnetic (TEM) cell, and a dual TEM cell constructed at ORNL from a design suggested by the NBS. The NBS coaxial fixture is an improved version of the device recommended by the American Society for Testing and Materials (ASTM). The problems associated with measuring SE are well described in the literature. The two methods described here are the result of years of work to establish procedures and instrumentation that will produce acceptable data.

  15. Electromagnetic brake/clutch device

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    1994-01-01

    An electromagnetic brake/clutch device includes a drive shaft supported by at least one bearing for transmitting torque, a housing, affixed to prevent its rotation, surrounding the drive shaft, and an electromagnetically activated device within the housing to selectively prevent and allow rotation of the drive shaft. The electromagnetically activated device includes a plurality of cammed rollers to prevent counter-clockwise rotation of the drive shaft. The drive shaft includes a circumferential disk and the housing includes a reaction ring for engagement with the plurality of cammed rollers. The plurality of cammed rollers are released from engagement with the circumferential disk and the reaction ring by a plurality of tripping mechanisms within the housing. The tripping action uses the locking force to act as a release force merely by changing the boundary conditions of the roller interface angles. The tripping mechanisms include trippers for disengaging the plurality of cammed rollers and an anvil shaped portion for providing lateral movement of the trippers. The plurality of cammed rollers is preloaded to engagement with the circumferential disk and reaction ring by a spring, and is located with respect to an adjacent tripping mechanism with another spring.

  16. Wind measurements by electromagnetic probes

    NASA Technical Reports Server (NTRS)

    Susko, Michael

    1988-01-01

    The emerging technology of electromagnetic probing of the atmosphere to measure winds used in a space vehicle ascent winds load calculations is presented. The frequency range, altitude, and resolution for the following probes are presented: lidars, microwave radars, and clear-air Doppler radars (popularly known as wind profilers). The electromagnetic probing of the atmosphere by clear-air radars and lasers is the new technology to supplement balloon-borne wind sensors used to determine ascent wind loads of space vehicles. The electromagnetic probes measure the wind velocity using the Doppler effect. This is the radar technology used in MSFC's Radar Wind Profiler, and is similar to the technology used in conventional Doppler systems except that the frequency is generally lower, antenna is bigger, and dwell time much longer. Designed for unattended and automated instrumentation in providing measurements of the wind in the troposphere, the profiler employs Doppler radar technology and is currently being put in operation at NASA Kennedy Space Center, Florida.

  17. Electromagnetic Effects in SDF Explosions

    SciTech Connect

    Reichenbach, H; Neuwald, P; Kuhl, A L

    2010-02-12

    The notion of high ion and electron concentrations in the detonation of aluminized explosive mixtures has aroused some interest in electro-magnetic effects that the SDF charges might generate when detonated. Motivated by this interest we have started to investigate whether significant electro-magnetic effects show up in our small-scale experiments. However, the design of instrumentation for this purpose is far from straightforward, since there are a number of open questions. Thus the main aim of the feasibility tests is to find - if possible - a simple and reliable method that can be used as a diagnostic tool for electro-magnetic effects. SDF charges with a 0.5-g PETN booster and a filling of 1 g aluminum flakes have been investigated in three barometric bomb calorimeters with volumes ranging from 6.3 l to of 6.6 l. Though similar in volume, the barometric bombs differed in the length-to-diameter ratio. The tests were carried out with the bombs filled with either air or nitrogen at ambient pressure. The comparison of the test in air to those in nitrogen shows that the combustion of TNT detonation products or aluminum generates a substantial increase of the quasi-steady overpressure in the bombs. Repeated tests in the same configuration resulted in some scatter of the experimental results. The most likely reason is that the aluminum combustion in most or all cases is incomplete and that the amount of aluminum actually burned varies from test to test. The mass fraction burned apparently decreases with increasing aspect ratio L/D. Thus an L/D-ratio of about 1 is optimal for the performance of shock-dispersed-fuel combustion. However, at an L/D-ratio of about 5 the combustion still yields appreciable overpressure in excess of the detonation. For a multi-burst scenario in a tunnel environment with a number of SDF charges distributed along a tunnel section a spacing of 5 tunnel diameter and a fuel-specific volume of around 7 l/g might provide an acceptable compromise between optimizing the combustion performance and keeping the number of elementary charges low. Further tests in a barometric bomb calorimeter of 21.2 l volume were performed with four types of aluminum. The mass fraction burned in this case appeared to depend on the morphology of the aluminum particles. Flake aluminum exhibited a better performance than granulated aluminum with particle sizes ranging from below 25 {micro}m to 125 {micro}m for the coarsest material. In addition, a feasibility study on electro-magnetic effects from SDF charges detonated in a tunnel has been performed. A method was developed to measure the local, unsteady electro-conductivity in the detonation/combustion products cloud. This method proved to yield reproducible results. A variety of methods were tested with regard to probing electro-magnetic pulses from the detonation of SDF charges. The results showed little reproducibility and were small compared to the effect from pulsed high voltage discharges of comparatively small energy (around 32 J). Thus either no significant electromagnetic pulse is generated in our small-scale tests or the tested techniques have to be discarded as too insensitive or too limited in bandwidth to detect possibly very high frequency electro-magnetic disturbances.

  18. Pulsed Electromagnet Emat for High Temperatures

    NASA Astrophysics Data System (ADS)

    Hernandez-Valle, F.; Dixon, S.

    2010-02-01

    We presented recently a design of Electromagnetic Acoustic Transducer (EMAT) that uses a pulsed electromagnet to provide the required magnetic field for operation. This new EMAT exhibited a significant improvement in the generated ultrasonic signal amplitude and signal to noise ratio, for operation on mild steel samples at room temperature, compared to equivalent EMATs that use permanent magnets. Results for using the pulsed electromagnet EMAT to generate and detect shear waves in mild steel at elevated temperatures are presented here.

  19. Manager's Role in Electromagnetic Interference (EMI) Control

    NASA Technical Reports Server (NTRS)

    Sargent, Noel B.; Lewis, Catherine C.

    2013-01-01

    This presentation captures the essence of electromagnetic compatibility (EMC) engineering from a project manager's perspective. It explains the basics of EMC and the benefits to the project of early incorporation of EMC best practices. The EMC requirement products during a project life cycle are identified, along with the requirement verification methods that should be utilized. The goal of the presentation is to raise awareness and simplify the mystique surrounding electromagnetic compatibility for managers that have little or no electromagnetics background

  20. Anisotropic conducting films for electromagnetic radiation applications

    DOEpatents

    Cavallo, Francesca; Lagally, Max G.; Rojas-Delgado, Richard

    2015-06-16

    Electronic devices for the generation of electromagnetic radiation are provided. Also provided are methods for using the devices to generate electromagnetic radiation. The radiation sources include an anisotropic electrically conducting thin film that is characterized by a periodically varying charge carrier mobility in the plane of the film. The periodic variation in carrier mobility gives rise to a spatially varying electric field, which produces electromagnetic radiation as charged particles pass through the film.

  1. Electromagnetic wave scattering by Schwarzschild black holes.

    PubMed

    Crispino, Luís C B; Dolan, Sam R; Oliveira, Ednilton S

    2009-06-12

    We analyze the scattering of a planar monochromatic electromagnetic wave incident upon a Schwarzschild black hole. We obtain accurate numerical results from the partial wave method for the electromagnetic scattering cross section and show that they are in excellent agreement with analytical approximations. The scattering of electromagnetic waves is compared with the scattering of scalar, spinor, and gravitational waves. We present a unified picture of the scattering of all massless fields for the first time. PMID:19658920

  2. Electromagnetic imaging methods for nondestructive evaluation applications.

    PubMed

    Deng, Yiming; Liu, Xin

    2011-01-01

    Electromagnetic nondestructive tests are important and widely used within the field of nondestructive evaluation (NDE). The recent advances in sensing technology, hardware and software development dedicated to imaging and image processing, and material sciences have greatly expanded the application fields, sophisticated the systems design and made the potential of electromagnetic NDE imaging seemingly unlimited. This review provides a comprehensive summary of research works on electromagnetic imaging methods for NDE applications, followed by the summary and discussions on future directions. PMID:22247693

  3. Electromagnetic Imaging Methods for Nondestructive Evaluation Applications

    PubMed Central

    Deng, Yiming; Liu, Xin

    2011-01-01

    Electromagnetic nondestructive tests are important and widely used within the field of nondestructive evaluation (NDE). The recent advances in sensing technology, hardware and software development dedicated to imaging and image processing, and material sciences have greatly expanded the application fields, sophisticated the systems design and made the potential of electromagnetic NDE imaging seemingly unlimited. This review provides a comprehensive summary of research works on electromagnetic imaging methods for NDE applications, followed by the summary and discussions on future directions. PMID:22247693

  4. Microfluidics for reconfigurable electromagnetic metamaterials

    NASA Astrophysics Data System (ADS)

    Kasirga, T. Serkan; Ertas, Y. Nuri; Bayindir, Mehmet

    2009-11-01

    We propose microfluidics as a useful platform for reconfigurable electromagnetic metamaterials. Microfluidic split-ring resonators (MF-SRRs) are fabricated inside a flexible elastomeric material by employing rapid prototyping. The transmission measurements performed for mercury-injected MF-SRR exhibits sharp magnetic resonances at microwave wavelengths. We further calculate transmission properties of the MF-SRR array and the effect of electrical conductivity of the liquid inside the channel on the magnetic resonance. The measured results agree well with numerical calculations. Our proposal may open up directions toward switchable metamaterials and reconfigurable devices such as filters, switches, and resonators.

  5. Extremely low frequency electromagnetic fields

    SciTech Connect

    Wilson, B.W. . Chemical Sciences Dept.); Stevens, R.G. ); Anderson, L.E. . Life Sciences Center)

    1990-01-01

    The authors focus on that which seems to be the central scientific issue emerging from current ELF research in epidemiology and in the laboratory; namely, can ELF electromagnetic fields interact with biological systems in such a way as to increase cancer risk The authors examine how cancer risk might be related to two reproducible biological effects of ELF exposure: effects on the pineal gland and circadian biology, and effects on calcium homeostasis in cells. Because they are concerned with the possible biological mechanisms of carcinogenesis, epidemiological studies are only briefly reviewed.

  6. An electromagnetic world without polarization

    NASA Astrophysics Data System (ADS)

    Zeldovich, B. Ya; Tsai, C.-C.

    2013-01-01

    The majority of natural sources (black-bodies, fluorescent bulbs, etc) generate completely un-polarized light; the majority of detectors (eyes, photo-cameras, photomultipliers, etc) are polarization-insensitive. To reflect this, we attempt to describe approximately electromagnetic waves without polarization. Corresponding scalar equations are non-trivial modifications of standard dAlembert and Helmholtz equations to the case of spatially inhomogeneous propagation speed v(\\mathbf{r})=1/\\sqrt{\\varepsilon (\\mathbf{r})\\mu (\\mathbf{r})}. A description of Fresnel reflection (FR) and Goos-Hnchen shift for total internal reflection phenomena is given on the basis of these modified equations.

  7. Electromagnetic weak turbulence theory revisited

    SciTech Connect

    Yoon, P. H.; Ziebell, L. F.; Gaelzer, R.; Pavan, J.

    2012-10-15

    The statistical mechanical reformulation of weak turbulence theory for unmagnetized plasmas including fully electromagnetic effects was carried out by Yoon [Phys. Plasmas 13, 022302 (2006)]. However, the wave kinetic equation for the transverse wave ignores the nonlinear three-wave interaction that involves two transverse waves and a Langmuir wave, the incoherent analogue of the so-called Raman scattering process, which may account for the third and higher-harmonic plasma emissions. The present paper extends the previous formalism by including such a term.

  8. Containerless processing using electromagnetic levitation

    NASA Technical Reports Server (NTRS)

    Gokhale, A. B.; Abbaschian, R.

    1990-01-01

    The theory and practice of containerless processing via electromagnetic (EM) levitation is reviewed briefly. The use of EM levitation for the processing of alloys is described with particular emphasis on the bulk melt supercooling phenomenon in a containerless environment. The various effects associated with rapid solidification via bulk melt supercooling are discussed with examples of Nb-Si alloys. It is suggested that a detailed analysis of such effects can be utilized to select the potentially most promising alloys for future space-based processing.

  9. Electromagnetic fields of energized conductors

    SciTech Connect

    Dawalibi, F.; Selby, A. )

    1993-07-01

    The electric field due to single-frequency current distribution in a buried horizontal rod with current leakage along its length and at its ends is computed for observation points at the soil-surface for low and high frequencies. The computation results are based on a general formulation which permits observation points in air or soil for an arbitrary network of energized conductors. The contribution of in-air and in-soil thin-wire conductors to electromagnetic fields are represented by path integrals.

  10. Electromagnetic properties of massive neutrinos

    SciTech Connect

    Dobrynina, A. A. Mikheev, N. V.; Narynskaya, E. N.

    2013-10-15

    The vertex function for a virtual massive neutrino is calculated in the limit of soft real photons. A method based on employing the neutrino self-energy operator in a weak external electromagnetic field in the approximation linear in the field is developed in order to render this calculation of the vertex function convenient. It is shown that the electric charge and the electric dipole moment of the real neutrino are zero; only the magnetic moment is nonzero for massive neutrinos. A fourth-generation heavy neutrino of mass not less than half of the Z-boson mass is considered as a massive neutrino.

  11. Electromagnetic Compatibility for the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Scully, Robert C.

    2004-01-01

    This slide presentation reviews the Space Shuttle electromagnetic compatibility (EMC). It includes an overview of the design of the shuttle with the areas that are of concern for the electromagnetic compatibility. It includes discussion of classical electromagnetic interference (EMI) and the work performed to control the electromagnetic interference. Another area of interest is electrostatic charging and the threat of electrostatic discharge and the attempts to reduce damage to the Shuttle from these possible hazards. The issue of electrical bonding is als reviewed. Lastly the presentation reviews the work performed to protect the shuttle from lightning, both in flight and on the ground.

  12. Electromagnetic effects on geodesic acoustic modes

    SciTech Connect

    Bashir, M. F.; Smolyakov, A. I.; Elfimov, A. G.; Melnikov, A. V.; Murtaza, G.

    2014-08-15

    By using the full electromagnetic drift kinetic equations for electrons and ions, the general dispersion relation for geodesic acoustic modes (GAMs) is derived incorporating the electromagnetic effects. It is shown that m = 1 harmonic of the GAM mode has a finite electromagnetic component. The electromagnetic corrections appear for finite values of the radial wave numbers and modify the GAM frequency. The effects of plasma pressure β{sub e}, the safety factor q, and the temperature ratio τ on GAM dispersion are analyzed.

  13. Calculation principles for a synchronous electromagnetic clutch

    NASA Technical Reports Server (NTRS)

    Panasenkov, M. A.

    1978-01-01

    A detailed explanation of the calculation principles, for a synchronous salient-pole electromagnetic clutch with lumped excitation windings is supplied by direct current. Practical recommendations are given.

  14. Detection of electromagnetic waves using MEMS antennas

    SciTech Connect

    Lavrik, Nickolay V; Tobin,; Bowland, Landon T

    2011-01-01

    We describe the design, fabrication and characterization of simple micromechanical structures that are capable of sensing static electric time varying electromagnetic fields. Time varying electric field sensing is usually achieved using an electromagnetic antenna and a receiver. However, these antenna-based approaches do not exhibit high sensitivity over a broad frequency (or wavelength) range. An important aspect of the present work is that, in contrast to traditional antennas, the dimensions of these micromechanical oscillators can be much smaller than the wavelength of the electromagnetic wave. We characterized the fabricated micromechanical oscillators by measuring their responses to time varying electric and electromagnetic fields.

  15. Electromagnetic compatibility of nuclear power plants

    SciTech Connect

    Cabayan, H.S.

    1983-01-01

    Lately, there has been a mounting concern about the electromagnetic compatibility of nuclear-power-plant systems mainly because of the effects due to the nuclear electromagnetic pulse, and also because of the introduction of more-sophisticated and, therefore, more-susceptible solid-state devices into the plants. Questions have been raised about the adequacy of solid-state-device protection against plant electromagnetic-interference sources and transients due to the nuclear electromagnetic pulse. In this paper, the author briefly reviews the environment, and the coupling, susceptibility, and vulnerability assessment issues of commercial nuclear power plants.

  16. Electromagnetic probes of the QGP

    NASA Astrophysics Data System (ADS)

    Bratkovskaya, E. L.; Linnyk, O.; Cassing, W.

    2015-05-01

    We investigate the properties of the QCD matter across the deconfinement phase transition in the scope of the parton-hadron string dynamics (PHSD) transport approach. We present here in particular the results on the electromagnetic radiation, i.e. photon and dilepton production, in relativistic heavy-ion collisions. By comparing our calculations for the heavy-ion collisions to the available data, we determine the relative importance of the various production sources and address the possible origin of the observed strong elliptic flow v2 of direct photons. We argue that the different centrality dependence of the hadronic and partonic sources for direct photon production in nucleusnucleus collisions can be employed to shed some more light on the origin of the photon v2 "puzzle". While the dilepton spectra at low invariant mass show in-medium effects like an enhancement from multiple baryonic resonance formation or a collisional broadening of the vector meson spectral functions, the dilepton yield at high invariant masses (above 1.1 GeV) is dominated by QGP contributions for central heavy-ion collisions at ultra-relativistic energies. This allows to have an independent view on the parton dynamics via their electromagnetic massive radiation.

  17. Electromagnetic Methods of Lightning Detection

    NASA Astrophysics Data System (ADS)

    Rakov, V. A.

    2013-11-01

    Both cloud-to-ground and cloud lightning discharges involve a number of processes that produce electromagnetic field signatures in different regions of the spectrum. Salient characteristics of measured wideband electric and magnetic fields generated by various lightning processes at distances ranging from tens to a few hundreds of kilometers (when at least the initial part of the signal is essentially radiation while being not influenced by ionospheric reflections) are reviewed. An overview of the various lightning locating techniques, including magnetic direction finding, time-of-arrival technique, and interferometry, is given. Lightning location on global scale, when radio-frequency electromagnetic signals are dominated by ionospheric reflections, is also considered. Lightning locating system performance characteristics, including flash and stroke detection efficiencies, percentage of misclassified events, location accuracy, and peak current estimation errors, are discussed. Both cloud and cloud-to-ground flashes are considered. Representative examples of modern lightning locating systems are reviewed. Besides general characterization of each system, the available information on its performance characteristics is given with emphasis on those based on formal ground-truth studies published in the peer-reviewed literature.

  18. Compton Sources of Electromagnetic Radiation

    SciTech Connect

    Geoffrey Krafft,Gerd Priebe

    2011-01-01

    When a relativistic electron beam interacts with a high-field laser beam, intense and highly collimated electromagnetic radiation will be generated through Compton scattering. Through relativistic upshifting and the relativistic Doppler effect, highly energetic polarized photons are radiated along the electron beam motion when the electrons interact with the laser light. For example, X-ray radiation can be obtained when optical lasers are scattered from electrons of tens-of-MeV beam energy. Because of the desirable properties of the radiation produced, many groups around the world have been designing, building, and utilizing Compton sources for a wide variety of purposes. In this review article, we discuss the generation and properties of the scattered radiation, the types of Compton source devices that have been constructed to date, and the prospects of radiation sources of this general type. Due to the possibilities of producing hard electromagnetic radiation in a device that is small compared to the alternative storage ring sources, it is foreseen that large numbers of such sources may be constructed in the future.

  19. Adaptive Multiscale Electromagnetic Particle Simulations

    NASA Astrophysics Data System (ADS)

    Omelchenko, Y. A.; Karimabadi, H.; Brown, M.; Catalyurek, U. V.; Saule, E.

    2010-11-01

    Hybrid (massless fluid electrons, kinetic ions) and full electromagnetic PIC simulations have recently emerged as powerful computational tools for predicting energetic particle transport in large-scale plasma configurations. Multiple time and length scales associated with plasma and magnetic field inhomogeneities put severe restrictions on the timestep and mesh resolution in these applications. We present two approaches intended to relieve these issues. An asynchronous hybrid code, HYPERS discards traditional time stepping in favor of Discrete-Event Simulation (DES). DES adaptively selects time increments for individual particles and local electromagnetic fields by limiting their per-update changes. HYPERS has been designed to simulate 3D compact fusion devices (such as the SSX experiment at Swarthmore) and interactions of streaming plasmas with obstacles. To validate this new code, we compare results from 2D HYPERS simulations with those obtained with a traditional (time-stepped) hybrid code. We also discuss a novel subgridding (EMPOWER) algorithm for full EM-PIC simulations and demonstrate its efficiency on test problems. Both codes are being geared towards peta/exa-scale computer architectures. We report our undergoing efforts on developing efficient dynamic load-balancing strategies for parallel production runs.

  20. Large-Scale Electromagnetic Simulation

    NASA Astrophysics Data System (ADS)

    Seidel, David B.

    1996-05-01

    The dramatic increase in computational capability that has occurred over the last ten years has allowed fully electromagnetic simulations of large, complex, multidimensional systems to move progressively from impractical, to expensive, and recently, to routine and widespread. This is particularly the case for systems that require the motion of free charge to be self-consistently treated. Several simulation tools have been developed to solve Maxwell's equations for both time-dependent problems, using finite difference and finite volume techniques, and time-harmonic problems, using boundary integral and finite element techniques. When required, several tools provide for the self-consistent treatment of free charge by integrating the Lorentz force equation, typically using the Particle-In-Cell (PIC) method. These tools have found widespread use for many diverse applications, including high-current electron and ion diodes, magnetically insulated power transmission systems, high-power microwave oscillators, high-frequency digital and analog integrated circuit packages, microwave integrated circuit components, antenna systems, radar cross-section applications, and electromagnetic interaction with biological material. This paper will give a brief overview of the various techniques used for such simulations, including a discussion of the effect of the architectures of modern high-performance computers on the implementation of those techniques. Also, some of the many simulation tools that are available will be described. As time permits, examples from several application areas will be presented.

  1. Interpreting Electromagnetic Reflections In Glaciology

    NASA Astrophysics Data System (ADS)

    Eisen, O.; Nixdorf, U.; Wilhelms, F.; Steinhage, D.; Miller, H.

    Electromagnetic reflection (EMR) measurements are active remote sensing methods that have become a major tool for glaciological investigations. Although the basic pro- cesses are well understood, the unambiguous interpretation of EMR data, especially internal layering, still requires further information. The Antacrtic ice sheet provides a unique setting for investigating the relation between physical­chemical properties of ice and EMR data. Cold ice, smooth surface topography, and low accumulation facilitates matters to use low energy ground penetrating radar (GPR) devices to pene- trate several tens to hundreds of meters of ice, covering several thousands of years of snow deposition history. Thus, sufficient internal layers, primarily of volcanic origin, are recorded to enable studies on a local and regional scale. Based on dated ice core records, GPR measurements at various frequencies, and airborne radio-echo sound- ing (RES) from Dronning Maud Land (DML), Antarctica, combined with numerical modeling techniques, we investigate the influence of internal layering characteristics and properties of the propagating electromagnetic wave on EMR data.

  2. Electromagnetic induction in the Earth

    NASA Astrophysics Data System (ADS)

    Fergurson, Ian; Slater, Lee; Queralt, Pilar; Ledo, Juanjo

    Measurements of electrical properties of the Earth using electromagnetic induction (EM) can elucidate geological structures and processes ranging from meter to mantle scale. The 18th International Workshop on Electromagnetic Induction in the Earth (EMIW) highlighted how recent theoretical and instrumental advances are being applied in high-quality EM induction studies from around the world, at lithospheric, crustal, and near-surface scales.Important aspects of the lithospheric and crustal studies presented included the demonstration of the increased resolution provided by dense two-dimensional magnetotelluric (MT) profiles and three-dimensional grids, the common use of the improved impedance tensor decomposition method to correct regional MT responses, widespread consideration of implicitly anisotropic materials within multidimensional MT models, and, in the numerical modeling field, the increased use of unstructured meshes. Review papers provided an overview of the large-scale EM surveys and spatial variations in the European lithosphere and addressed the role of EM in monitoring seismic and volcanic crustal processes.

  3. Electromagnetic scattering from buried objects

    SciTech Connect

    Brock, B.C.; Sorensen, K.W.

    1994-10-01

    Radar imaging and detection of objects buried in soil has potentially important applications in the areas of nonproliferation of weapons, environmental monitoring, hazardous-waste site location and assessment, and even archeology. In order to understand and exploit this potential, it is first necessary to understand how the soil responds to an electromagnetic wave, and how targets buried within the soil scatter the electromagnetic wave. We examine the response of the soil to a short pulse, and illustrate the roll of the complex dielectric permittivity of the soil in determining radar range resolution. This leads to a concept of an optimum frequency and bandwidth for imaging in a particular soil. We then propose a new definition for radar cross section which is consistent with the modified radar equation for use with buried targets. This radar cross section plays the same roll in the modified radar equation as the traditional radar cross section does in the free-space radar equation, and is directly comparable to it. The radar cross section of several canonical objects in lossy media is derived, and examples are given for several object/soil combinations.

  4. Electromagnetic wave energy conversion research

    NASA Technical Reports Server (NTRS)

    Bailey, R. L.; Callahan, P. S.

    1975-01-01

    Known electromagnetic wave absorbing structures found in nature were first studied for clues of how one might later design large area man-made radiant-electric converters. This led to the study of the electro-optics of insect dielectric antennae. Insights were achieved into how these antennae probably operate in the infrared 7-14um range. EWEC theoretical models and relevant cases were concisely formulated and justified for metal and dielectric absorber materials. Finding the electromagnetic field solutions to these models is a problem not yet solved. A rough estimate of losses in metal, solid dielectric, and hollow dielectric waveguides indicates future radiant-electric EWEC research should aim toward dielectric materials for maximum conversion efficiency. It was also found that the absorber bandwidth is a theoretical limitation on radiant-electric conversion efficiency. Ideally, the absorbers' wavelength would be centered on the irradiating spectrum and have the same bandwith as the irradiating wave. The EWEC concept appears to have a valid scientific basis, but considerable more research is needed before it is thoroughly understood, especially for the complex randomly polarized, wide band, phase incoherent spectrum of the sun. Specific recommended research areas are identified.

  5. Millimeter Waves: Acoustic and Electromagnetic

    PubMed Central

    Ziskin, Marvin C.

    2012-01-01

    This article is the presentation I gave at the D'Arsonval Award Ceremony on June 14, 2011 at the Bioelectromagnetics Society Annual Meeting in Halifax, Nova Scotia. It summarizes my research activities in acoustic and electromagnetic millimeter waves over the past 47 years. My earliest research involved acoustic millimeter waves, with a special interest in diagnostic ultrasound imaging and its safety. For the last 21 years my research expanded to include electromagnetic millimeter waves, with a special interest in the mechanisms underlying millimeter wave therapy. Millimeter wave therapy has been widely used in the former Soviet Union with great reported success for many diseases, but is virtually unknown to Western physicians. I and the very capable members of my laboratory were able to demonstrate that the local exposure of skin to low intensity millimeter waves caused the release of endogenous opioids, and the transport of these agents by blood flow to all parts of the body resulted in pain relief and other beneficial effects. PMID:22926874

  6. Quantization of Electromagnetic Fields in Cavities

    NASA Technical Reports Server (NTRS)

    Kakazu, Kiyotaka; Oshiro, Kazunori

    1996-01-01

    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.

  7. Project Physics Tests 4, Light and Electromagnetism.

    ERIC Educational Resources Information Center

    Harvard Univ., Cambridge, MA. Harvard Project Physics.

    Test items relating to Project Physics Unit 4 are presented in this booklet. Included are 70 multiple-choice and 22 problem-and-essay questions. Concepts of light and electromagnetism are examined on charges, reflection, electrostatic forces, electric potential, speed of light, electromagnetic waves and radiations, Oersted's and Faraday's work,…

  8. Electromagnetic Induction Rediscovered Using Original Texts.

    ERIC Educational Resources Information Center

    Barth, Michael

    2000-01-01

    Describes a teaching unit on electromagnetic induction using historic texts. Uses some of Faraday's diary entries from 1831 to introduce the phenomenon of electromagnetic induction and teach about the properties of electricity, of taking conclusions from experiment, and scientific methodology. (ASK)

  9. Narrow field electromagnetic sensor system and method

    DOEpatents

    McEwan, Thomas E.

    1996-01-01

    A narrow field electromagnetic sensor system and method of sensing a characteristic of an object provide the capability to realize a characteristic of an object such as density, thickness, or presence, for any desired coordinate position on the object. One application is imaging. The sensor can also be used as an obstruction detector or an electronic trip wire with a narrow field without the disadvantages of impaired performance when exposed to dirt, snow, rain, or sunlight. The sensor employs a transmitter for transmitting a sequence of electromagnetic signals in response to a transmit timing signal, a receiver for sampling only the initial direct RF path of the electromagnetic signal while excluding all other electromagnetic signals in response to a receive timing signal, and a signal processor for processing the sampled direct RF path electromagnetic signal and providing an indication of the characteristic of an object. Usually, the electromagnetic signal is a short RF burst and the obstruction must provide a substantially complete eclipse of the direct RF path. By employing time-of-flight techniques, a timing circuit controls the receiver to sample only the initial direct RF path of the electromagnetic signal while not sampling indirect path electromagnetic signals. The sensor system also incorporates circuitry for ultra-wideband spread spectrum operation that reduces interference to and from other RF services while allowing co-location of multiple electronic sensors without the need for frequency assignments.

  10. Narrow field electromagnetic sensor system and method

    DOEpatents

    McEwan, T.E.

    1996-11-19

    A narrow field electromagnetic sensor system and method of sensing a characteristic of an object provide the capability to realize a characteristic of an object such as density, thickness, or presence, for any desired coordinate position on the object. One application is imaging. The sensor can also be used as an obstruction detector or an electronic trip wire with a narrow field without the disadvantages of impaired performance when exposed to dirt, snow, rain, or sunlight. The sensor employs a transmitter for transmitting a sequence of electromagnetic signals in response to a transmit timing signal, a receiver for sampling only the initial direct RF path of the electromagnetic signal while excluding all other electromagnetic signals in response to a receive timing signal, and a signal processor for processing the sampled direct RF path electromagnetic signal and providing an indication of the characteristic of an object. Usually, the electromagnetic signal is a short RF burst and the obstruction must provide a substantially complete eclipse of the direct RF path. By employing time-of-flight techniques, a timing circuit controls the receiver to sample only the initial direct RF path of the electromagnetic signal while not sampling indirect path electromagnetic signals. The sensor system also incorporates circuitry for ultra-wideband spread spectrum operation that reduces interference to and from other RF services while allowing co-location of multiple electronic sensors without the need for frequency assignments. 12 figs.

  11. Upper High School Students' Understanding of Electromagnetism

    ERIC Educational Resources Information Center

    Saglam, Murat; Millar, Robin

    2006-01-01

    Although electromagnetism is an important component of upper secondary school physics syllabuses in many countries, there has been relatively little research on students' understanding of the topic. A written test consisting of 16 diagnostic questions was developed and used to survey the understanding of electromagnetism of upper secondary school

  12. The Teaching of Electromagnetism at University Level

    ERIC Educational Resources Information Center

    Houldin, J. E.

    1974-01-01

    Discusses different kinds of material presentation in the teaching of electromagnetism at the university level, including three "classical" approaches and the Keller personalized proctorial system. Indicates that a general introduction to generators and motors may be useful in an electromagnetism course. (CC)

  13. Pulsed power requirements for electromagnetic launches

    NASA Astrophysics Data System (ADS)

    Weldon, W. F.; Woodson, H. H.

    1986-02-01

    Both linear (railgun) and coaxial (mass driver, etc.) electromagnetic launchers (EMLS) are treated as time-varying impedances to determine the relationships between acceleration force, payload velocity, and power supply voltage and current. These relationships are then examined in the light of electromagnetic parameters associated with each EML type ot establish a basis for determining and comparing power supply requirements for various EMLs.

  14. Assessment and control of spacecraft electromagnetic interference

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Design criteria are presented to provide guidance in assessing electromagnetic interference from onboard sources and establishing requisite control in spacecraft design, development, and testing. A comprehensive state-of-the-art review is given which covers flight experience, sources and transmission of electromagnetic interference, susceptible equipment, design procedure, control techniques, and test methods.

  15. NASA Applications for Computational Electromagnetic Analysis

    NASA Technical Reports Server (NTRS)

    Lewis, Catherine C.; Trout, Dawn H.; Krome, Mark E.; Perry, Thomas A.

    2011-01-01

    Computational Electromagnetic Software is used by NASA to analyze the compatibility of systems too large or too complex for testing. Recent advances in software packages and computer capabilities have made it possible to determine the effects of a transmitter inside a launch vehicle fairing, better analyze the environment threats, and perform on-orbit replacements with assured electromagnetic compatibility.

  16. Ultrashort electromagnetic pulses in graphene with disorder

    NASA Astrophysics Data System (ADS)

    Konobeeva, N. N.; Belonenko, M. B.

    2015-08-01

    Maxwell's equations describing an electromagnetic field propagating in graphene with disorder are analyzed. The spectrum of electrons for the graphene subsystem is chosen based on the renormalization group approach. An effective equation governing the vector potential of the electromagnetic field is derived and solved numerically. The dependence of the pulse shape on parameters of the problem is investigated.

  17. Upper High School Students' Understanding of Electromagnetism

    ERIC Educational Resources Information Center

    Saglam, Murat; Millar, Robin

    2006-01-01

    Although electromagnetism is an important component of upper secondary school physics syllabuses in many countries, there has been relatively little research on students' understanding of the topic. A written test consisting of 16 diagnostic questions was developed and used to survey the understanding of electromagnetism of upper secondary school…

  18. Electromagnetic emission in mineral and rock dehydration

    NASA Astrophysics Data System (ADS)

    Salnikov, V.; Popov, V.; Terre, D.

    2016-03-01

    The article considers regularities of radiofrequency electromagnetic radiation from minerals and rocks, with samples being heated in a vacuum to 20° C- 1000° C. The examples of electromagnetic emission correlation with electric conductivity, thermoluminescence and thermographic analysis during physic-chemical processes resulting from diagenesis, catagenesis and metagenesis have been provided.

  19. Electromagnetic Concepts in Mathematical Representation of Physics.

    ERIC Educational Resources Information Center

    Albe, Virginie; Venturini, Patrice; Lascours, Jean

    2001-01-01

    Addresses the use of mathematics when studying the physics of electromagnetism. Focuses on common electromagnetic concepts and their associated mathematical representation and arithmetical tools. Concludes that most students do not understand the significant aspects of physical situations and have difficulty using relationships and models specific…

  20. ELECTROMAGNETIC APPARATUS FOR MOVING A ROD

    DOEpatents

    Young, J.N.

    1957-08-20

    An electromagnetic device for moving an object in a linear path by increments is described. The device is specifically adapted for moving a neutron absorbing control rod into and out of the core of a reactor and consists essentially of an extension member made of magnetic material connected to one end of the control rod and mechanically flexible to grip the walls of a sleeve member when flexed, a magnetic sleeve member coaxial with and slidable between limit stops along the flexible extension, electromagnetic coils substantially centrally located with respect to the flexible extension to flex the extension member into gripping engagement with the sleeve member when ener gized, moving electromagnets at each end of the sleeve to attract the sleeve when energized, and a second gripping electromagnet positioned along the flexible extension at a distance from the previously mentioned electromagnets for gripping the extension member when energized. In use, the second gripping electromagnet is deenergized, the first gripping electromagnet is energized to fix the extension member in the sleeve, and one of the moving electromagnets is energized to attract the sleeve member toward it, thereby moving the control rod.

  1. Electromagnetic Concepts in Mathematical Representation of Physics.

    ERIC Educational Resources Information Center

    Albe, Virginie; Venturini, Patrice; Lascours, Jean

    2001-01-01

    Addresses the use of mathematics when studying the physics of electromagnetism. Focuses on common electromagnetic concepts and their associated mathematical representation and arithmetical tools. Concludes that most students do not understand the significant aspects of physical situations and have difficulty using relationships and models specific

  2. Electromagnetic bonding of plastics to aluminum

    NASA Technical Reports Server (NTRS)

    Sheppard, A. T.; Silbert, L.

    1980-01-01

    Electromagnetic curing is used to bond strain gage to aluminum tensile bar. Electromagnetic energy heats only plastic/metal interface by means of skin effect, preventing degradation of heat-treated aluminum. Process can be easily applied to other metals joined by high-temperature-curing plastic adhesives.

  3. Electromagnets 1: Turn on the Power. Science in a Box.

    ERIC Educational Resources Information Center

    Whitman, Betsy Blizard

    1992-01-01

    The article presents inexpensive activities to teach elementary school students about electromagnets. Students learn to make an electromagnet with a battery, nail, and wire, then different activities help them explore the difference between permanent magnets and electromagnets. (SM)

  4. On electromagnetic and quantum invisibility

    NASA Astrophysics Data System (ADS)

    Mundru, Pattabhiraju Chowdary

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

  5. Noninvasive valve monitor using alternating electromagnetic field

    DOEpatents

    Eissenberg, David M.; Haynes, Howard D.; Casada, Donald A.

    1993-01-01

    One or more electrical coils are carefully located on the outside of a valve body. An alternating current passing through the coil(s) results in an alternating electromagnetic field being transmitted into the valve body and valve internals. The electromagnetic field varies in intensity and polarity in the valve. As the position of a valve internal part is changed, the electromagnetic field throughout the valve body and its internals is altered. A passive receiver coil carefully located on the outside of the valve body detects the intensity of the electromagnetic field at that location as an induced electrical voltage in the coil. With the change in position of the valve internal part, there is a corresponding change in the induced voltage as a result of the alteration in the alternating electromagnetic field at that location. Changes in the voltage provide an indication of the position and motion of valve internals.

  6. Noninvasive valve monitor using alternating electromagnetic field

    DOEpatents

    Eissenberg, D.M.; Haynes, H.D.; Casada, D.A.

    1993-03-16

    One or more electrical coils are carefully located on the outside of a valve body. An alternating current passing through the coil(s) results in an alternating electromagnetic field being transmitted into the valve body and valve internals. The electromagnetic field varies in intensity and polarity in the valve. As the position of a valve internal part is changed, the electromagnetic field throughout the valve body and its internals is altered. A passive receiver coil carefully located on the outside of the valve body detects the intensity of the electromagnetic field at that location as an induced electrical voltage in the coil. With the change in position of the valve internal part, there is a corresponding change in the induced voltage as a result of the alteration in the alternating electromagnetic field at that location. Changes in the voltage provide an indication of the position and motion of valve internals.

  7. Structural composites with integrated electromagnetic functionality

    NASA Astrophysics Data System (ADS)

    Nemat-Nasser, Syrus C.; Amirkhizi, Alireza V.; Plaisted, Thomas; Isaacs, Jon; Nemat-Nasser, Siavouche

    2002-07-01

    We are studying the incorporation of electromagnetic effective media in the form of arrays of metal scattering elements, such as wires, into polymer-based or ceramic-based composites. In addition to desired structural properties, these electromagnetic effective media can provide controlled response to electromagnetic radiation such as RF communication signals, radar, and/or infrared radiation. With the addition of dynamic components, these materials may be leveraged for active tasks such as filtering. The advantages of such hybrid composites include simplicity and weight savings by the combination of electromagnetic functionality with necessary structural functionality. This integration of both electromagnetic and structural functionality throughout the volume of the composite is the distinguishing feature of our approach. As an example, we present a class of composites based on the integration of artificial plasmon media into polymer matrixes. Such composites can exhibit a broadband index of refraction substantially equal to unity at microwave frequencies and below.

  8. Hypercube-Computer Analysis Of Electromagnetic Scattering

    NASA Technical Reports Server (NTRS)

    Patterson, J. E.; Liewer, P. C.; Calalo, R. H.; Manshadi, F.

    1990-01-01

    Capabilities of hypercube and parallel processing demonstrated. Report describes use of Mark III Hypercube computer to analyze scattering of electromagnetic waves. Purpose of study to assess utility of parallel computing in such computation-intensive problems as large-scale electromagnetic scattering. Two electromagnetic codes based on different algorithms converted to run on Mark III Hypercube. First code implements finite-difference, time-domain solution of Maxwell's curl equations. Second code is Numerical Electromagnetics Code (NEC-2) which embodies frequency-domain method and developed to analyze electromagnetic responses of antennas and other metallic structures. On Mark III Hypercube with 32 active nodes, largest lattice contains about 2,048,000 unit cells.

  9. Electromagnetic launcher: A new weapon

    NASA Astrophysics Data System (ADS)

    Brooks, A. L.; Hawke, R. S.

    1981-08-01

    There are several perceived advantages to using Electromagnetic (EM) launching for weapons applications. Higher muzzle velocities than can be achieved with conventional ordnance will minimize the projectile time-of-flight to the target; this is of particular interest for air-defense applications against maneuvering targets and for penetrator launching. The potential for precise current (hence acceleration) control promises lower peak accelerations that the projectile must withstand, and much more precise muzzle velocity control, permitting the use of smart projectiles and continuous zoning for artillery applications. The principles behind EM accelerators, particularly dc accelerators (railguns), the recent history of their development, their advantages for weapons applications, the general requirements, potential problem areas that must be faced by designers, and the work that has been done by researchers at Livermore and Los Alamos National Laboratories in accelerating 3-g projectiles to 10 km/s, and larger masses to lower velocities are discussed.

  10. Electromagnetic launchers for space applications

    NASA Technical Reports Server (NTRS)

    Schroeder, J. M.; Gully, J. H.; Driga, M. D.

    1989-01-01

    An electromagnetic launcher (EML) was designed for NASA-Langley to boost large models to hypervelocity for flight evaluation. Two different concepts were developed using railgun and coilgun principles. A coilgun was designed to accelerate a 14-kg mass to 6 km/s and, by adding additional equipment, to accelerate a 10-kg mass to 11 km/s. The railgun system was designed to accelerate only 14 kg to 6 km/s. Of significance in this development is the opportunity to use the launcher for aeroballistic research of the upper atmosphere, eventually placing packages in low earth orbit using a small rocket. The authors describe the railgun and coilgun launch designs and suggest a reconfiguration for placement of 150-kg parcels into low earth orbit for aeroballistic studies and possible space lab support. Each design is detailed along with the performance adjustments which would be required for circular orbit payload placement.

  11. Efficient transformer for electromagnetic waves

    DOEpatents

    Miller, R.B.

    A transformer structure for efficient transfer of electromagnetic energy from a transmission line to an unmatched load provides voltage multiplication and current division by a predetermined constant. Impedance levels are transformed by the square of that constant. The structure includes a wave splitter, connected to an input transmission device and to a plurality of output transmission devices. The output transmission devices are effectively connected in parallel to the input transmission device. The output transmission devices are effectively series connected to provide energy to a load. The transformer structure is particularly effective in increasing efficiency of energy transfer through an inverting convolute structure by capturing and transferring energy losses from the inverter to the load.

  12. The CLAS Forward Electromagnetic Calorimeter

    SciTech Connect

    M. Amarian; Geram Asryan; Kevin Beard; Will Brooks; Volker Burkert; Tom Carstens; Alan Coleman; Raphael Demirchyan; Yuri Efremenko; Hovanes Egiyan; Kim Egiyan; Herb Funsten; Vladimir Gavrilov; Kevin L. Giovanetti; R.M. Marshall; Berhard Mecking; R.C. Minehart; H. Mkrtchan; Mavrik Ohandjanyan; Youri Sharabian; L.C. Smith; Stepan Stepanyan; W.A. Stephens; T.Y. Tung; Carl Zorn

    2001-05-01

    The CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab utilizes six iron-free superconducting coils to provide an approximately toroidal magnetic field. The six sectors are instrumented individually to form six independent spectrometers. The forward region (8deg < (theta) < 45deg) of each sector is equipped with a lead-scintillator electromagnetic sampling calorimeter (EC), 16 radiation lengths thick, using a novel triangular geometry with stereo readout. With its good energy and position resolution, the EC is used to provide the primary electron trigger for CLAS. It is also used to reject pions, reconstruct pi-0 and eta decays and detect neutrons, This paper treats the design, construction and performance of the calorimeter.

  13. 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.

  14. Spatially dependent electromagnetically induced transparency.

    PubMed

    Radwell, N; Clark, T W; Piccirillo, B; Barnett, S M; Franke-Arnold, S

    2015-03-27

    Recent years have seen vast progress in the generation and detection of structured light, with potential applications in high capacity optical data storage and continuous variable quantum technologies. Here we measure the transmission of structured light through cold rubidium atoms and observe regions of electromagnetically induced transparency (EIT), using the phase profile as control parameter for the atomic opacity. With q plates we generate a probe beam with azimuthally varying phase and polarization structure, and its right and left circular polarization components provide the probe and control of an EIT transition. We observe an azimuthal modulation of the absorption profile that is dictated by the phase and polarization structure of the probe laser. Conventional EIT systems do not exhibit phase sensitivity. We show, however, that a weak transverse magnetic field closes the EIT transitions, thereby generating phase-dependent dark states which in turn lead to phase-dependent transparency, in agreement with our measurements. PMID:25860744

  15. Electromagnetic Calorimeter for Hades Experiment

    NASA Astrophysics Data System (ADS)

    Kugler, A.; Blume, C.; Czyžycki, W.; Epple, E.; Fabbietti, L.; Galatyuk, T.; Golubeva, M.; Guber, F.; Hlaváč, S.; Ivashkin, A.; Kajetanowic, M.; Kardan, B.; Koenig, W.; Lapidus, K.; Lisowski, E.; Pietraszko, J.; Reshetin, A.; Rost, A.; Salabura, P.; Sobolev, Y. G.; Svoboda, O.; Tlusty, P.; Traxler, M.

    2014-06-01

    Electromagnetic calorimeter (ECAL) is being developed to complement the dilepton spectrometer HADES currently operating at GSI Darmstadt, Germany. ECAL will enable the HADES@FAIR experiment to measure data on neutral meson production in heavy ion collisions at the energy range of 2-10 A GeV on the beam of future accelerator SIS100@FAIR. The calorimeter will also improve the electron-hadron separation and will as well be used for the detection of photons from strange resonances in elementary and heavy ion reactions. Calorimeter modules constructed of lead glass Cherenkov counter, photomultiplier, HV divider and optical fiber are described in the detail. Two prototypes of novel front-end electronics based on TRB3 are presented. A dedicated LED based system being developed to monitor the stability of the calorimeter during beamtime is introduced as well.

  16. Electromagnetic Induction with Neodymium Magnets

    NASA Astrophysics Data System (ADS)

    Wood, Deborah; Sebranek, John

    2013-09-01

    In April 1820, Hans Christian Ørsted noticed that the needle of a nearby compass deflected briefly from magnetic north each time the electric current of the battery he was using for an unrelated experiment was turned on or off. Upon further investigation, he showed that an electric current flowing through a wire produces a magnetic field. In 1831 Michael Faraday and Joseph Henry separately expanded on Ørsted's discovery by showing that a changing magnetic field produces an electric current. Heinrich Lenz found in 1833 that an induced current has the opposite direction from the electromagnetic force that produced it. This paper describes an experiment that can help students to develop an understanding of Faraday's law and Lenz's law by studying the emf generated as a magnet drops through a set of coils having increasing numbers of turns.

  17. Tracking Electromagnetic Energy With SQUIDs

    NASA Technical Reports Server (NTRS)

    2005-01-01

    A superconducting quantum interference device (SQUID) is a gadget used to measure extremely weak signals, specifically magnetic flux. It can detect subtle changes in energy, up to 100 billion times weaker than the electromagnetic energy required to move a compass needle. SQUIDs are used for a variety of testing procedures where extreme sensitivity is required and where the test instrument need not come into direct contact with the test subject. NASA uses SQUIDs for remote, noncontact sensing in a variety of venues, including monitoring the Earth s magnetic field and tracking brain activity of pilots. Scientists at NASA s Goddard Space Flight Center have been making extensive use of this technology, from astrophysical research, to tracking the navigational paths of bees in flight to determine if they are using internal compasses. These very sensitive measurement devices have a wide variety of uses within NASA and even more uses within the commercial realm.

  18. Formal analysis of electromagnetic optics

    NASA Astrophysics Data System (ADS)

    Khan-Afshar, Sanaz; Hasan, Osman; Tahar, Sofiène

    2014-09-01

    Optical systems are increasingly being used in safety-critical applications. Due to the complexity and sensitivity of optical systems, their verification raises many challenges for engineers. Traditionally, the analysis of such systems has been carried out by paper-and-pencil based proofs and numerical computations. However, these techniques cannot provide accurate results due to the risk of human error and inherent approximations of numerical algorithms. In order to overcome these limitations, we propose to use theorem proving (i.e., a computer-based technique that allows to express mathematical expressions and reason about their correctness by taking into account all the details of mathematical reasoning) as a complementary approach to improve optical system analysis. This paper provides a higher-order logic (a language used to express mathematical theories) formalization of electromagnetic optics in the HOL Light theorem prover. In order to demonstrate the practical effectiveness of our approach, we present the analysis of resonant cavity enhanced photonic devices.

  19. Electromagnetic interaction with uniaxial metamaterials

    NASA Astrophysics Data System (ADS)

    Tedeschi, N.; Frezza, F.; Sihvola, A.

    2015-07-01

    In this paper, the reflection behavior of a particular class of metamaterials, strongly connected with the realization of the DB boundary conditions (so called due to the vanishing of the normal components of the D and B fluxes) and the soft and hard (SH) boundary conditions, is presented. The metamaterial under study is modeled as an anisotropic, uniaxial, material with both permittivity and permeability dyadics. We consider several characteristics of such medium: presenting the critical angle of total transmission for the SH/DB material, analyzing its behavior as a function of the longitudinal permittivity and permeability, for both positive and negative values, and presenting its applications to the electromagnetic absorbers and to the polarization inverters.

  20. Electromagnetic scattering by impedance structures

    NASA Technical Reports Server (NTRS)

    Balanis, Constantine A.; Griesser, Timothy

    1987-01-01

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

  1. Electromagnetic braking for Mars spacecraft

    NASA Technical Reports Server (NTRS)

    Holt, A. C.

    1986-01-01

    Aerobraking concepts are being studied to improve performance and cost effectiveness of propulsion systems for Mars landers and Mars interplanetary spacecraft. Access to megawatt power levels (nuclear power coupled to high-storage inductive or capacitive devices) on a manned Mars interplanetary spacecraft may make feasible electromagnetic braking and lift modulation techniques which were previously impractical. Using pulsed microwave and magnetic field technology, potential plasmadynamic braking and hydromagnetic lift modulation techniques have been identified. Entry corridor modulation to reduce loads and heating, to reduce vertical descent rates, and to expand horizontal and lateral landing ranges are possible benefits. In-depth studies are needed to identify specific design concepts for feasibility assessments. Standing wave/plasma sheath interaction techniques appear to be promising. The techniques may require some tailoring of spacecraft external structures and materials. In addition, rapid response guidance and control systems may require the use of structurally embedded sensors coupled to expert systems or to artificial intelligence systems.

  2. Electromagnetic Signatures of SMBH Coalescence

    NASA Technical Reports Server (NTRS)

    Schnittman, Jeremy

    2012-01-01

    When two supermassive black holes (SMBHs) approach within 1-10 mpc, gravitational wave (GW) losses begin to dominate the evolution of the binary, pushing the system to merge in a relatively small time. During this final inspiral regime, the system will emit copious energy in GWs, which should be directly detectable by pulsar timing arrays and space-based interferometers. At the same time, any gas or stars in the immediate vicinity of the merging 5MBHs can get heated and produce bright electromagnetic (EM) counterparts to the GW signals. We present here a number of possible mechanisms by which simultaneous EM and GW signals will yield valuable new information about galaxy evolution, accretion disk dynamics, and fundamental physics in the most extreme gravitational fields.

  3. Broadband cavity electromagnetically induced transparency

    SciTech Connect

    Wei Xiaogang; Wang Yanhua; Zhang Jiepeng; Zhu Yifu

    2011-10-15

    Cavity electromagnetically induced transparency (EIT) is created in a three-level atomic system confined in a cavity and coupled to a free-space control laser and is manifested as a narrow transmission peak of a probe laser coupled into the cavity mode and tuned to the two-photon Raman resonance with the control laser. Cavity EIT can be observed with a control laser detuned from the atomic transition frequency in a range limited by the vacuum Rabi splitting of two cavity-atom normal modes. This leads to the broadband cavity EIT obtained in the coupled-cavity-atom system with a free-space, broadband control laser. We report an experimental observation of broadband cavity EIT in cold Rb atoms with a frequency-modulated control laser and discuss its application in multichannel and multifrequency light memory.

  4. An electromagnetic micro=undulator

    SciTech Connect

    Nassiri, A.; Turner, L.R.

    1997-12-31

    Microfabrication technology using the LIGA (a German acronym for Lithography, Electroforming, and Molding) process offers an attractive alternative for fabricating precision devices with micron-sized features. One such device is a mm-sized micro-undulator with potential applications in a table-top synchrotron light source for medical and other industrial uses. The undulator consists of a silver conductor embedded in poles and substrate of nickel-iron. Electromagnetic modeling of the undulator is done using the eddy current computer code ELEKTRA. Computations predict a field pattern of appropriate strength and quality if the current can be prevented from being shunted from silver by the nickel-iron poles either through insulation or through slotted poles. The design of the undulator along with the computational results are discussed.

  5. Electromagnetic Coupling in Layered Superconductors

    NASA Astrophysics Data System (ADS)

    Blatter, Gianni

    1996-03-01

    The low-field (B < φ_circ/λ^2) phenomenological phase diagram of layered superconductors is attracting a lot of interest (in BiSCCO B < φ_circ/λ^2 ≈ 600 G). Important issues are the shape and nature of the phase transitions involving melting of the vortex lattice and layer decoupling. We determine (within a Lindemann approach) the position and shape of the melting line in a layered superconductor, emphasizing the importance of electromagnetic interactions in the vortex system. In the limit of vanishing Josephson coupling, we obtain a new generic reentrant low-field melting line B_m^em ~ (Φ_circ/λ^2) c_ L^2 \\varepsilon_circ d /T (here, \\varepsilon_circ denotes the line energy (Φ_circ/4 π λ)^2 and d is the layer thickness; we cite the result for the upper branch only). Finite Josephson coupling (producing a finite anisotropy parameter \\varepsilon^2 = m/M << 1) pushes this melting line to higher temperatures and fields and a new line shape B_m^em,J ~ (Φ_circ/λ^2) c_ L^2 \\varepsilon_circ \\varepsilon λ/T ∝ (1-T/T_c)^3/2 is found. The usual line shape B_m^J ~ (Φ_circ/λ^2) c_ L^4 \\varepsilon_circ \\varepsilon^2 λ^2/T^2 is only recovered at fields B > Φ_circ/λ^2. The new expressions exhibit important differences in the parametric dependencies of the melting line on anisotropy \\varepsilon, Lindemann number c_ L, and penetration depth λ ∝ (1-T/T_c)-1/2. Similarly, the shape of the decoupling line is strongly modified by the influence of electromagnetic coupling. We construct the low-field phase diagram including melting and decoupling lines and discuss various experiments in the light of our new results. Work done in collaboration with V. Geshkenbein, A. Larkin, and H. Nordborg.

  6. Electromagnetically induced frame dragging around astrophysical objects

    NASA Astrophysics Data System (ADS)

    Gutiérrez-Ruiz, Andrés F.; Pachón, Leonardo A.

    2015-06-01

    Frame dragging (Lense-Thirring effect) is generally associated with rotating astrophysical objects. However, it can also be generated by electromagnetic fields if electric and magnetic fields are simultaneously present. In most models of astrophysical objects, macroscopic charge neutrality is assumed and the entire electromagnetic field is characterized in terms of a magnetic dipole component. Hence, the purely electromagnetic contribution to the frame dragging vanishes. However, strange stars may possess independent electric dipole and neutron stars independent electric quadrupole moments that may lead to the presence of purely electromagnetic contributions to the frame dragging. Moreover, recent observations have shown that in stars with strong electromagnetic fields, the magnetic quadrupole may have a significant contribution to the dynamics of stellar processes. As an attempt to characterize and quantify the effect of electromagnetic frame dragging in these kinds of astrophysical objects, an analytic solution to the Einstein-Maxwell equations is constructed here on the basis that the electromagnetic field is generated by the combination of arbitrary magnetic and electric dipoles plus arbitrary magnetic and electric quadrupole moments. The effect of each multipole contribution on the vorticity scalar and the Poynting vector is described in detail. Corrections on important quantities such the innermost stable circular orbit (ISCO) and the epicyclic frequencies are also considered.

  7. Modeling Electromagnetic Scattering From Complex Inhomogeneous Objects

    NASA Technical Reports Server (NTRS)

    Deshpande, Manohar; Reddy, C. J.

    2011-01-01

    This software innovation is designed to develop a mathematical formulation to estimate the electromagnetic scattering characteristics of complex, inhomogeneous objects using the finite-element-method (FEM) and method-of-moments (MoM) concepts, as well as to develop a FORTRAN code called FEMOM3DS (Finite Element Method and Method of Moments for 3-Dimensional Scattering), which will implement the steps that are described in the mathematical formulation. Very complex objects can be easily modeled, and the operator of the code is not required to know the details of electromagnetic theory to study electromagnetic scattering.

  8. Electromagnetic waves in gravitational wave spacetimes

    NASA Astrophysics Data System (ADS)

    Bini, Donato; Fortini, Pierluigi; Haney, Maria; Ortolan, Antonello

    2011-12-01

    We have considered the propagation of electromagnetic waves in a spacetime representing an exact gravitational plane wave and calculated the induced changes on the four-potential field Aμ of a plane electromagnetic wave. By choosing a suitable photon round trip in a Michelson interferometer, we have been able to identify the physical effects of the exact gravitational wave on the electromagnetic field, i.e. phase shift, change of the polarization vector, angular deflection and delay. These results have been exploited to study the response of an interferometric gravitational wave detector beyond the linear approximation of the general theory of relativity.

  9. Electromagnetic Characterization Of Metallic Sensory Alloy

    NASA Technical Reports Server (NTRS)

    Wincheski, Russell A.; Simpson, John; Wallace, Terryl A.; Newman, John A.; Leser, Paul; Lahue, Rob

    2012-01-01

    Ferromagnetic shape-memory alloy (FSMA) particles undergo changes in both electromagnetic properties and crystallographic structure when strained. When embedded in a structural material, these attributes can provide sensory output of the strain state of the structure. In this work, a detailed characterization of the electromagnetic properties of a FSMA under development for sensory applications is performed. In addition, a new eddy current probe is used to interrogate the electromagnetic properties of individual FSMA particles embedded in the sensory alloy during controlled fatigue tests on the multifunctional material.

  10. Young's experiment with electromagnetic spatial coherence wavelets.

    PubMed

    Castaneda, Roman; Carrasquilla, Juan; Garcia-Sucerquia, Jorge

    2006-10-01

    We discuss Young's experiment with electromagnetic random fields at arbitrary states of coherence and polarization within the framework of the electric spatial coherence wavelets. The use of this approach for the electromagnetic spatial coherence theory allows us to envisage the existence of polarization domains inside the observation plane. We show that it is possible to locally control those polarization domains by means of the correlation properties of the electromagnetic wave. To show the validity of this alternative approach, we derive by means of numerical modeling the classical Fresnel-Arago interference laws. PMID:16985537

  11. Development of a strong electromagnet wiggler

    SciTech Connect

    Burns, M.J.; Deis, G.A.; Holmes, R.H.; Van Maren, R.D.; Halbach, K.

    1987-01-01

    The Strong Electromagnet (SEM) wiggler is a permanent magnet-assisted electromagnet under development at the Lawrence Livermore National Laboratory (LLNL) as part of the Induction Linac Free-Electron-Laser (IFEL) program. This concept uses permanent magnets within the wiggler to provide a reverse bias flux in the iron and thus delay the onset of magnetic saturation. The electromagnet coils determine the wiggler field and operate at low current densities by virtue of their placement away from the midplane. We describe here the design approach used and test data from a 7-period wiggler prototype that includes curved pole tips to provide wiggle-plane focusing. 7 refs.

  12. An AWE Implementation for Electromagnetic Analysis

    NASA Technical Reports Server (NTRS)

    Gong, Jian; Volakis, John L.

    1996-01-01

    Although full wave electromagnetic systems are large and cumbersome to solve, typically only a few parameters, such as input impedance, S parameters, and far field pattern, are needed by the designer or analyst. A reduced order modeling of these parameters is therefore an important consideration in minimizing the the CPU requirements. The Asymptotic Waveform Evaluation (AWE) method is one approach to construct a reduced order model of the input impedance or other useful electromagnetic parameters. We demonstrate its application and validity when used in conjunction with the finite element method to simulate full wave electromagnetic problems.

  13. Detection of electromagnetic waves using charged cantilevers

    NASA Astrophysics Data System (ADS)

    Datskos, P. G.; Lavrik, N. V.; Tobin, J. D.; Bowland, L. T.

    2012-03-01

    We describe micromechanical structures that are capable of sensing both electrostatic fields and electromagnetic fields over a wide frequency range. Typically, sensing of electromagnetic waves is achieved with electrically conducting antennas, which despite the many advantages do not exhibit high sensitivity over a broad frequency range. An important aspect of our present work is that, in contrast to traditional antennas, the dimensions of micromechanical oscillators sensitive to electromagnetic waves can be much smaller than the wavelength. We characterized the micromechanical oscillators and measured responses to electric fields and estimated the performance limits by evaluating the signal-to-noise ratio theoretically and experimentally.

  14. Porous material for protection from electromagnetic radiation

    SciTech Connect

    Kazmina, Olga E-mail: bdushkina89@mail.ru; Dushkina, Maria E-mail: bdushkina89@mail.ru; Suslyaev, Valentin; Semukhin, Boris

    2014-11-14

    It is shown that the porous glass crystalline material obtained by a low temperature technology can be used not only for thermal insulation, but also for lining of rooms as protective screens decreasing harmful effect of electromagnetic radiation as well as to establish acoustic chambers and rooms with a low level of electromagnetic background. The material interacts with electromagnetic radiation by the most effective way in a high frequency field (above 100 GHz). At the frequency of 260 GHz the value of the transmission coefficient decreases approximately in a factor times in comparison with foam glass.

  15. Electromagnetic launch of lunar material

    NASA Technical Reports Server (NTRS)

    Snow, William R.; Kolm, Henry H.

    1992-01-01

    Lunar soil can become a source of relatively inexpensive oxygen propellant for vehicles going from low Earth orbit (LEO) to geosynchronous Earth orbit (GEO) and beyond. This lunar oxygen could replace the oxygen propellant that, in current plans for these missions, is launched from the Earth's surface and amounts to approximately 75 percent of the total mass. The reason for considering the use of oxygen produced on the Moon is that the cost for the energy needed to transport things from the lunar surface to LEO is approximately 5 percent the cost from the surface of the Earth to LEO. Electromagnetic launchers, in particular the superconducting quenchgun, provide a method of getting this lunar oxygen off the lunar surface at minimal cost. This cost savings comes from the fact that the superconducting quenchgun gets its launch energy from locally supplied, solar- or nuclear-generated electrical power. We present a preliminary design to show the main features and components of a lunar-based superconducting quenchgun for use in launching 1-ton containers of liquid oxygen, one every 2 hours. At this rate, nearly 4400 tons of liquid oxygen would be launched into low lunar orbit in a year.

  16. Medical applications of electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Lai, Henry C.; Singh, Narendra P.

    2010-04-01

    In this article, we describe two possible applications of low-intensity non-ionizing electromagnetic fields (EMF) for the treatment of malaria and cancer, respectively. In malaria treatment, a low-intensity extremely-low frequency magnetic field can be used to induce vibration of hemozoin, a super-paramagnetic polymer particle, inside malaria parasites. This disturbance could cause free radical and mechanical damages leading to the death of the parasite. This concept has been tested in vitro on malaria parasites and found to be effective. This may provide a low cost effective treatment for malaria infection in humans. The rationale for cancer treatment using low-intensity EMF is based on two concepts that have been well established in the literature: (1) low-intensity non-thermal EMF enhances cytotoxic free radicals via the iron-mediated Fenton reaction; and (2) cancer cells have higher amounts of free iron, thus are more susceptible to the cytotoxic effects of EMF. Since normal cells contain minimal amount of free iron, the effect would be selectively targeting cancer cells. Thus, no adverse side effect would be expected as in traditional chemotherapy and radiation therapy. This concept has also been tested on human cancer cell and normal cells in vitro and proved to be feasible.

  17. Electromagnetic launch of lunar material

    NASA Astrophysics Data System (ADS)

    Snow, William R.; Kolm, Henry H.

    Lunar soil can become a source of relatively inexpensive oxygen propellant for vehicles going from low Earth orbit (LEO) to geosynchronous Earth orbit (GEO) and beyond. This lunar oxygen could replace the oxygen propellant that, in current plans for these missions, is launched from the Earth's surface and amounts to approximately 75 percent of the total mass. The reason for considering the use of oxygen produced on the Moon is that the cost for the energy needed to transport things from the lunar surface to LEO is approximately 5 percent the cost from the surface of the Earth to LEO. Electromagnetic launchers, in particular the superconducting quench-gun, provide a method of getting this lunar oxygen off the lunar surface at minimal cost. This cost savings comes from the fact that the superconducting quench-gun gets its launch energy from locally supplied, solar- or nuclear-generated electrical power. We present a preliminary design to show the main features and components of a lunar-based superconducting quench-gun for use in launching 1-ton containers of liquid oxygen, one every 2 hours. At this rate, nearly 4400 tons of liquid oxygen would be launched into low lunar orbit in a year.

  18. Analysis of nonlinear electromagnetic metamaterials

    NASA Astrophysics Data System (ADS)

    Poutrina, Ekaterina; Huang, Da; Smith, David R.

    2010-09-01

    We analyze the properties of a nonlinear metamaterial formed by integrating nonlinear components or materials into the capacitive regions of metamaterial elements. A straightforward homogenization procedure leads to general expressions for the nonlinear susceptibilities of the composite metamaterial medium. The expressions are convenient, as they enable an inhomogeneous system of scattering elements to be described as a continuous medium using the standard notation of nonlinear optics. We illustrate the validity and accuracy of our theoretical framework by performing measurements on a fabricated metamaterial sample composed of an array of split ring resonators (SRRs) with packaged varactors embedded in the capacitive gaps, in a manner similar to that of Wang et al (2008 Opt. Express 16 16058). Because the SRRs exhibit a predominantly magnetic response to electromagnetic fields, the varactor-loaded SRR composite can be described as a magnetic material with nonlinear terms in its effective magnetic susceptibility. Treating the composite as a nonlinear effective medium, we can quantitatively assess the performance of the medium to enhance and facilitate nonlinear processes, including second harmonic generation, three- and four-wave mixing, self-focusing and other well-known nonlinear phenomena. We illustrate the accuracy of our approach by predicting the intensity-dependent resonance frequency shift in the effective permeability of the varactor-loaded SRR medium and comparing with experimental measurements.

  19. Electromagnetic properties of superparamagnetic nanocomposites

    NASA Astrophysics Data System (ADS)

    Desmarest, C.; Gadenne, P.; Noguès, M.; Sztern, J.; Naud, C.; Bontemps, N.; Djordjevic, S.; Gadenne, M.

    2000-04-01

    We report here new experimental results on superparamagnetic nanocomposites. We compare experimental transmission measurements with calculations based on the Onsager local field, taking into account the permanent magnetic moment of the particles. Optical measurements are performed on a Fourier transform spectrometer in the far infrared range, and on a microwave setup. Usually, superparamagnetic relaxation is understood by comparing the relaxation time τ of the magnetic moment of the particle with the measuring time τm. According to Néel's model τ is temperature dependent. In our case, τm is given by the electromagnetic wave period. As this experimental technique has been proved to be relevant to investigate superparamagnetism relaxation, we check it with two kinds of nanocomposites: Ni (ferromagnetic) embedded in alumina or aluminum nitride matrix and γ-Fe 2O 3 particles (ferrimagnetic) in a polymer. The dominant anisotropy is magnetocrystalline for Ni and shape and/or surface for γ-Fe 2O 3. This difference leads to different transmission behaviors while changing sample temperature from 5 to 300 K. The magnetocrystalline anisotropy shows up temperature dependence while the shape or surface anisotropies do not.

  20. Electromagnetic fields in cased borehole

    SciTech Connect

    Lee, Ki Ha; Kim, Hee Joon; Uchida, Toshihiro

    2001-07-20

    Borehole electromagnetic (EM) measurements, using fiberglass-cased boreholes, have proven useful in oil field reservoir characterization and process monitoring (Wilt et al., 1995). It has been presumed that these measurements would be impossible in steel-cased wells due to the very large EM attenuation and phase shifts. Recent laboratory and field studies have indicated that detection of EM signals through steel casing should be possible at low frequencies, and that these data provide a reasonable conductivity image at a useful scale. Thus, we see an increased application of this technique to mature oilfields, and an immediate extension to geothermal industry as well. Along with the field experiments numerical model studies have been carried out for analyzing the effect of steel casing to the EM fields. The model used to be an infinitely long uniform casing embedded in a homogeneous whole space. Nevertheless, the results indicated that the formation signal could be accurately recovered if the casing characteristics were independently known (Becker et al., 1998; Lee el al., 1998). Real steel-cased wells are much more complex than the simple laboratory models used in work to date. The purpose of this study is to develop efficient numerical methods for analyzing EM fields in realistic settings, and to evaluate the potential application of EM technologies to cross-borehole and single-hole environment for reservoir characterization and monitoring.

  1. Aircraft Lightning Electromagnetic Environment Measurement

    NASA Technical Reports Server (NTRS)

    Ely, Jay J.; Nguyen, Truong X.; Szatkowski, George N.

    2011-01-01

    This paper outlines a NASA project plan for demonstrating a prototype lightning strike measurement system that is suitable for installation onto research aircraft that already operate in thunderstorms. This work builds upon past data from the NASA F106, FAA CV-580, and Transall C-180 flight projects, SAE ARP5412, and the European ILDAS Program. The primary focus is to capture airframe current waveforms during attachment, but may also consider pre and post-attachment current, electric field, and radiated field phenomena. New sensor technologies are being developed for this system, including a fiber-optic Faraday polarization sensor that measures lightning current waveforms from DC to over several Megahertz, and has dynamic range covering hundreds-of-volts to tens-of-thousands-of-volts. A study of the electromagnetic emission spectrum of lightning (including radio wave, microwave, optical, X-Rays and Gamma-Rays), and a compilation of aircraft transfer-function data (including composite aircraft) are included, to aid in the development of other new lightning environment sensors, their placement on-board research aircraft, and triggering of the onboard instrumentation system. The instrumentation system will leverage recent advances in high-speed, high dynamic range, deep memory data acquisition equipment, and fiber-optic interconnect.

  2. Octonionic matrix representation and electromagnetism

    NASA Astrophysics Data System (ADS)

    Chanyal, B. C.

    2014-12-01

    Keeping in mind the important role of octonion algebra, we have obtained the electromagnetic field equations of dyons with an octonionic 8×8 matrix representation. In this paper, we consider the eight — dimensional octonionic space as a combination of two (external and internal) four-dimensional spaces for the existence of magnetic monopoles (dyons) in a higher-dimensional formalism. As such, we describe the octonion wave equations in terms of eight components from the 8 × 8 matrix representation. The octonion forms of the generalized potential, fields and current source of dyons in terms of 8 × 8 matrix are discussed in a consistent manner. Thus, we have obtained the generalized Dirac-Maxwell equations of dyons from an 8×8 matrix representation of the octonion wave equations in a compact and consistent manner. The generalized Dirac-Maxwell equations are fully symmetric Maxwell equations and allow for the possibility of magnetic charges and currents, analogous to electric charges and currents. Accordingly, we have obtained the octonionic Dirac wave equations in an external field from the matrix representation of the octonion-valued potentials of dyons.

  3. Parallel computation of electromagnetic fields

    SciTech Connect

    Madsen, N.K.

    1997-05-21

    The DSI3D code is designed to numerically solve electromagnetics problems involving complex objects by solving Maxwell`s curl equations in the time-domain and in three space dimensions. The code has been designed to run on the new parallel processing computers as well as on conventional serial computers. The DSI3D code is unique for the following reasons: It runs efficiently on a variety of parallel computers, Allows the use of unstructured non-orthogonal grids, Allows a variety of cell or element types, Reduces to be the Finite Difference Time Domain (FDID) method when orthogonal grids are used, Preserves charge or divergence locally (and globally), Is non- dissipative, and Is accurate for non-orthogonal grids. This method is derived using a Discrete Surface Integration (DSI) technique. As formulated, the DSI technique can be used with essentially arbitrary unstructured grids composed of convex polyhedral cells. This implementation of the DSI algorithm allows the use of unstructured grids that are composed of combinations of non-orthogonal hexahedrons, tetrahedrons, triangular prisms and pyramids. This algorithm reduces to the conventional FDTD method when applied on a structured orthogonal hexahedral grid.

  4. Electromagnetic antenna modeling (EAM) system

    NASA Astrophysics Data System (ADS)

    Packer, Malcolm; Powers, Robert; Tsitsopoulos, Paul

    1994-12-01

    The determination of foreign communications capabilities and intent is an important assessment function performed by the USAF National Air Intelligence Center (NAIC). In this context, Rome Laboratory became the NAIC engineering agent for the development of an NAIC requirement for the rapid analysis and evaluation of antenna structures based on often vague to sometimes detailed dimensional information. To this end, the Rome Laboratory sponsored development of the Electromagnetic Antenna Modeling (EAM) System, a state-of-the-art Pascal program with an MS Windows graphical user interface (GUI) pre- and post-processor. Users of NAIC capabilities initiate antenna analysis efforts that range from simple parametric studies to more complex, detailed antenna design and communication-system evaluations. Accordingly, EAM provides a modeling capability 'matched' to the sophistication of the individual analyst, with features appropriate for users ranging from nontechnical analysts to experienced antenna engineers. This capability is particularly valuable in the military-intelligence environment, in which high-speed assessments are required. In particular, EAM meets the specific antenna-analysis requirements of NAIC with a versatile graphical user interface.

  5. Avionics electromagnetic interference immunity and environment

    NASA Technical Reports Server (NTRS)

    Clarke, C. A.

    1986-01-01

    Aircraft electromagnetic spectrum and radio frequency (RF) field strengths are charted, profiling the higher levels of electromagnetic voltages encountered by the commercial aircraft wiring. Selected military, urban, and rural electromagnetic field levels are plotted and provide a comparison of radiation amplitudes. Low frequency magnetic fields and electric fields from 400 H(Z) power systems are charted versus frequency and wire separation to indicate induced voltages on adjacent or neighboring circuits. Induced EMI levels and attenuation characteristics of electric, magnetic, RF fields, and transients are plotted and graphed for common types of wire circuits. The significance of wire circuit returns and shielding is emphasized to highlight the techniques that help block the paths of electromagnetic interference and maintain avionic interface signal quality.

  6. Advanced high-temperature electromagnetic pump

    NASA Technical Reports Server (NTRS)

    Gahan, J. W.; Powell, A. H.

    1972-01-01

    Three phase helical, electromagnetic induction pump for use as boiler feed pump in potassium Rankine-cycle power system is described. Techniques for fabricating components of pump are discussed. Specifications of pump are analyzed.

  7. Computes Generalized Electromagnetic Interactions Between Structures

    Energy Science and Technology Software Center (ESTSC)

    1999-02-20

    Object oriented software for computing generalized electromagnetic interactions between structures in the frequency domains. The software is based on integral equations. There is also a static integral equation capability.

  8. Progress In Electromagnetics Research Symposium (PIERS)

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The third Progress In Electromagnetics Research Symposium (PIERS) was held 12-16 Jul. 1993, at the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California. More than 800 presentations were made, and those abstracts are included in this publication.

  9. Galium Electromagnetic (GEM) Thruster Concept and Design

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Markusic, Thomas E.

    2005-01-01

    We describe the design of a new type of two-stage pulsed electromagnetic accelerator, the gallium electromagnetic (GEM) thruster. A schematic illustration of the GEM thruster concept is given. In this concept, liquid gallium propellant is pumped into the first stage through a porous metal electrode using an electromagnetic pump. At a designated time, a pulsed discharge (approx. 10-50 J) is initiated in the first stage, ablating the liquid gallium from the porous electrode surface and ejecting a dense thermal gallium plasma into the second state. The presence of the gallium plasma in the second stage serves to trigger the high-energy (approx. 500 J), second-stage pulse which provides the primary electromagnetic (j x B) acceleration.

  10. Electromagnetic radiation from beam-plasma instabilities

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    The mechanism by which unstable electrostatic waves of an electron-beam plasma system are converted into observed electromagnetic waves is of great current interest in space plasma physics. Electromagnetic radiation arises from both natural beam-plasma systems, e.g., type III solar bursts and kilometric radiation, and from man-made electron beams injected from rockets and spacecraft. In the present investigation the diagnostic difficulties encountered in space plasmas are overcome by using a large laboratory plasma. A finite diameter (d approximately equal to 0.8 cm) electron beam is injected into a uniform quiescent magnetized afterglow plasma of dimensions large compared with electromagnetic wavelength. Electrostatic waves grow, saturate and decay within the uniform central region of the plasma volume so that linear mode conversion on density gradients can be excluded as a possible generation mechanism for electromagnetic waves.

  11. Method and apparatus for measuring electromagnetic radiation

    NASA Technical Reports Server (NTRS)

    Been, J. F. (Inventor)

    1973-01-01

    An apparatus and method are described in which the capacitance of a semiconductor junction subjected to an electromagnetic radiation field is utilized to indicate the intensity or strength of the radiation.

  12. Electrical wire insulation and electromagnetic coil

    DOEpatents

    Bich, George J.; Gupta, Tapan K.

    1984-01-01

    An electromagnetic coil for high temperature and high radiation application in which glass is used to insulate the electrical wire. A process for applying the insulation to the wire is disclosed which results in improved insulation properties.

  13. Tabletop Models for Electrical and Electromagnetic Geophysics.

    ERIC Educational Resources Information Center

    Young, Charles T.

    2002-01-01

    Details the use of tabletop models that demonstrate concepts in direct current electrical resistivity, self-potential, and electromagnetic geophysical models. Explains how data profiles of the models are obtained. (DDR)

  14. Electromagnetic Fields and Public Health: Mobile Phones

    MedlinePlus

    ... Features Commentaries 2014 Multimedia Contacts Electromagnetic fields and public health: mobile phones Fact sheet N°193 Reviewed October ... important to investigate, understand and monitor any potential public health impact. Mobile phones communicate by transmitting radio waves ...

  15. Electromagnetic thrusters for spacecraft prime propulsion

    NASA Technical Reports Server (NTRS)

    Rudolph, L. K.; King, D. Q.

    1984-01-01

    The benefits of electromagnetic propulsion systems for the next generation of US spacecraft are discussed. Attention is given to magnetoplasmadynamic (MPD) and arc jet thrusters, which form a subset of a larger group of electromagnetic propulsion systems including pulsed plasma thrusters, Hall accelerators, and electromagnetic launchers. Mission/system study results acquired over the last twenty years suggest that for future prime propulsion applications high-power self-field MPD thrusters and low-power arc jets have the greatest potential of all electromagnetic thruster systems. Some of the benefits they are expected to provide include major reductions in required launch mass compared to chemical propulsion systems (particularly in geostationary orbit transfer) and lower life-cycle costs (almost 50 percent less). Detailed schematic drawings are provided which describe some possible configurations for the various systems.

  16. Nanomechanical electric and electromagnetic field sensor

    SciTech Connect

    Datskos, Panagiotis George; Lavrik, Nickolay

    2015-03-24

    The present invention provides a system for detecting and analyzing at least one of an electric field and an electromagnetic field. The system includes a micro/nanomechanical oscillator which oscillates in the presence of at least one of the electric field and the electromagnetic field. The micro/nanomechanical oscillator includes a dense array of cantilevers mounted to a substrate. A charge localized on a tip of each cantilever interacts with and oscillates in the presence of the electric and/or electromagnetic field. The system further includes a subsystem for recording the movement of the cantilever to extract information from the electric and/or electromagnetic field. The system further includes a means of adjusting a stiffness of the cantilever to heterodyne tune an operating frequency of the system over a frequency range.

  17. Serpentine Robot Arm Contains Electromagnetic Actuators

    NASA Technical Reports Server (NTRS)

    Moya, Israel A.; Studer, Philip A.

    1994-01-01

    Identical modules assembled into flexible robot arm configured in serpentlike fashion to manipulate objects while avoiding obstacles. Each module includes integral electromagnetic actuators energized selectively to produce variety of motions, stationary configurations, and combinations thereof.

  18. Nonlocal theory of electromagnetic wave decay into two electromagnetic waves in a rippled density plasma channel

    SciTech Connect

    Sati, Priti; Tripathi, V. K.

    2012-12-15

    Parametric decay of a large amplitude electromagnetic wave into two electromagnetic modes in a rippled density plasma channel is investigated. The channel is taken to possess step density profile besides a density ripple of axial wave vector. The density ripple accounts for the momentum mismatch between the interacting waves and facilitates nonlinear coupling. For a given pump wave frequency, the requisite ripple wave number varies only a little w.r.t. the frequency of the low frequency decay wave. The radial localization of electromagnetic wave reduces the growth rate of the parametric instability. The growth rate decreases with the frequency of low frequency electromagnetic wave.

  19. Calculation of electromagnetic force in electromagnetic forming process of metal sheet

    SciTech Connect

    Xu Da; Liu Xuesong; Fang Kun; Fang Hongyuan

    2010-06-15

    Electromagnetic forming (EMF) is a forming process that relies on the inductive electromagnetic force to deform metallic workpiece at high speed. Calculation of the electromagnetic force is essential to understand the EMF process. However, accurate calculation requires complex numerical solution, in which the coupling between the electromagnetic process and the deformation of workpiece needs be considered. In this paper, an appropriate formula has been developed to calculate the electromagnetic force in metal work-piece in the sheet EMF process. The effects of the geometric size of coil, the material properties, and the parameters of discharge circuit on electromagnetic force are taken into consideration. Through the formula, the electromagnetic force at different time and in different positions of the workpiece can be predicted. The calculated electromagnetic force and magnetic field are in good agreement with the numerical and experimental results. The accurate prediction of the electromagnetic force provides an insight into the physical process of the EMF and a powerful tool to design optimum EMF systems.

  20. Apparatus and Methods for Mitigating Electromagnetic Emissions

    NASA Technical Reports Server (NTRS)

    Geng, Steven M. (Inventor); Niedra, Janis M. (Inventor)

    2013-01-01

    Apparatus, methods, and other embodiments associated with mitigation of magnetic fields are described herein. In an embodiment, a method for mitigating an electromagnetic field includes positioning a mitigating coil around a linear alternator of linear motor so that the mitigating coil is coaxially located with an alternator coil; arranging the mitigating coil to generate a field to mitigate an electromagnetic field generated by the alternator coil; and passing an induced current from the alternator coil through the mitigating coil.

  1. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, J.T.

    1997-06-24

    An apparatus and method are disclosed for generating homogeneous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set. 26 figs.

  2. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, James T.

    1998-01-01

    An apparatus and method for generating homogenous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set.

  3. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, James Terry

    1998-01-01

    An apparatus and method for generating homogenous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set.

  4. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, James T.

    1997-01-01

    An apparatus and method for generating homogenous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially cancelling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set.

  5. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, J.T.

    1998-02-10

    An apparatus and method for generating homogeneous electromagnetic fields within a volume is disclosed. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set. 39 figs.

  6. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, J.T.

    1998-05-05

    An apparatus and method are disclosed for generating homogeneous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set. 55 figs.

  7. Low-Frequency Electromagnetic Backscattering from Tunnels

    SciTech Connect

    Casey, K; Pao, H

    2007-01-16

    Low-frequency electromagnetic scattering from one or more tunnels in a lossy dielectric half-space is considered. The tunnel radii are assumed small compared to the wavelength of the electromagnetic field in the surrounding medium; a tunnel can thus be modeled as a thin scatterer, described by an equivalent impedance per unit length. We examine the normalized backscattering width for cases in which the air-ground interface is either smooth or rough.

  8. Electromagnetic Transport From Microtearing Mode Turbulence

    SciTech Connect

    Guttenfelder, W; Kaye, S M; Nevins, W M; Wang, E; Bell, R E; Hammett, G W; LeBlanc, B P; Mikkelsen, D R

    2011-03-23

    This Letter presents non-linear gyrokinetic simulations of microtearing mode turbulence. The simulations include collisional and electromagnetic effects and use experimental parameters from a high beta discharge in the National Spherical Torus Experiment (NSTX). The predicted electron thermal transport is comparable to that given by experimental analysis, and it is dominated by the electromagnetic contribution of electrons free streaming along the resulting stochastic magnetic field line trajectories. Experimental values of flow shear can significantly reduce the predicted transport.

  9. Apparatus and Methods for Mitigating Electromagnetic Emissions

    NASA Technical Reports Server (NTRS)

    Geng, Steven M. (Inventor); Niedra, Janis M. (Inventor)

    2016-01-01

    Apparatus, methods, and other embodiments associated with mitigation of magnetic fields are described herein. In an embodiment, a method for mitigating an electromagnetic field includes positioning a mitigating coil around a linear alternator of linear motor so that the mitigating coil is coaxially located with an alternator coil; arranging the mitigating coil to generate a field to mitigate an electromagnetic field generated by the alternator coil; and passing an induced current from the alternator coil through the mitigating coil.

  10. Electromagnetic Transport from Microtearing Mode Turbulence

    SciTech Connect

    Guttenfelder, W.; Kaye, S. M.; Bell, R. E.; Hammett, G. W.; LeBlanc, B. P.; Mikkelsen, D. R.; Candy, J.; Nevins, W. M.; Wang, E.; Yuh, H.

    2011-04-15

    This Letter presents nonlinear gyrokinetic simulations of microtearing mode turbulence. The simulations include collisional and electromagnetic effects and use experimental parameters from a high-{beta} discharge in the National Spherical Torus Experiment. The predicted electron thermal transport is comparable to that given by experimental analysis, and it is dominated by the electromagnetic contribution of electrons free-streaming along the resulting stochastic magnetic field line trajectories. Experimental values of flow shear can significantly reduce the predicted transport.

  11. High-Power Electromagnetic Thruster Being Developed

    NASA Technical Reports Server (NTRS)

    LaPointe, Michael R.; Mikellides, Pavlos G.

    2001-01-01

    High-power electromagnetic thrusters have been proposed as primary in-space propulsion options for several bold new interplanetary and deep-space missions. As the lead center for electric propulsion, the NASA Glenn Research Center designs, develops, and tests high-power electromagnetic technologies to meet these demanding mission requirements. Two high-power thruster concepts currently under investigation by Glenn are the magnetoplasmadynamic (MPD) thruster and the Pulsed Inductive Thruster (PIT).

  12. Electromagnetic Heating Methods for Heavy Oil Reservoirs

    SciTech Connect

    Sahni, A.; Kumar, M.; Knapp, R.B.

    2000-05-01

    The most widely used method of thermal oil recovery is by injecting steam into the reservoir. A well-designed steam injection project is very efficient in recovering oil, however its applicability is limited in many situations. Simulation studies and field experience has shown that for low injectivity reservoirs, small thickness of the oil-bearing zone, and reservoir heterogeneity limits the performance of steam injection. This paper discusses alternative methods of transferring heat to heavy oil reservoirs, based on electromagnetic energy. They present a detailed analysis of low frequency electric resistive (ohmic) heating and higher frequency electromagnetic heating (radio and microwave frequency). They show the applicability of electromagnetic heating in two example reservoirs. The first reservoir model has thin sand zones separated by impermeable shale layers, and very viscous oil. They model preheating the reservoir with low frequency current using two horizontal electrodes, before injecting steam. The second reservoir model has very low permeability and moderately viscous oil. In this case they use a high frequency microwave antenna located near the producing well as the heat source. Simulation results presented in this paper show that in some cases, electromagnetic heating may be a good alternative to steam injection or maybe used in combination with steam to improve heavy oil production. They identify the parameters which are critical in electromagnetic heating. They also discuss past field applications of electromagnetic heating including technical challenges and limitations.

  13. ALICE electromagnetic calorimeter prototype test

    SciTech Connect

    Awes, Terry; /Oak Ridge

    2005-09-01

    This Memorandum of Understanding between the Test Beam collaborators and Fermilab is for the use of beam time at Fermilab during the Fall, 2005 Meson Test Beam Run. The experimenters plan to measure the energy, position, and time resolution of prototype modules of a large electromagnetic calorimeter proposed to be installed in the ALICE experiment at the LHC. The ALICE experiment is one of the three large approved LHC experiments, with ALICE placing special emphasis on the LHC heavy-ion program. The large electromagnetic calorimeter (EMCal) is a US initiative that is endorsed by the ALICE collaboration and is currently in the early stages of review by the Nuclear Physics Division of the DOE. The installation in the test beam at FNAL and test beam measurements will be carried out by the US members of the ALICE collaboration (ALICE-USA). The overall design of the ALICE EMCal is heavily influenced by its location within the ALICE L3 magnet. The EMCal is to be located inside the large room temperature magnet within a cylindrical integration volume approximately l12cm deep, by 5.6m in length, sandwiched between the ALICE TPC space frame and the L3 magnet coils. The chosen technology is a layered Pb-scintillator sampling calorimeter with a longitudinal pitch of 1.6mm Pb and 1.6mm scintillator. The full detector spans {eta} = -0.7 to {eta} = 0.7 with an azimuthal acceptance of {Delta}{phi} = 120{sup o}. The EMCal readout is of a ''Shish-Kabob'' type similar to the PHENIX Pb-scintillator sampling calorimeter in which the scintillation light is collected via wavelength shifting fibers running through the Pb-scintillator tiles perpendicular to the front surface. The detector is segmented into {approx}14000 towers. The basic structural units of the calorimeter are supermodules, each subtending approximately {approx}20{sup o} in {Delta}{phi} and 0.7 units in {Delta}{eta}. Supermodules are assembled from individual modules. The modules are further segmented into 2 x 2 individually read out towers. The fibers from an individual tower are grouped together to form readout tower bundles. These are each optically coupled to an avalanche photodiode (APO) via a short light guide to provide some spatial optical mixing and to match the fiber bundle to the APO. The module assembly is indicated in Figure l. The supermodules weigh about 9.6 tons and are the basic units handled during installation. Each supermodule is roughly I45cm wide at the front surface by 350cm long with an active depth of 24.5cm (at {eta} = 0) plus an additional 6.6 cm of depth in structural plates. The physical characteristics of the ALICE EMCal are summarized in Table 1. The EMCal test beam measurements at FNAL will utilize a stacked 4 x 4 array of prototype EMCal modules (8 x 8 towers). All towers will be instrumented with the same model APO and preamplifier as will be used in the ALICE experiment and all channels will be readout with existing prototype front end electronics intended for use in ALICE. The goals of the test beam measurements are: To investigate the energy resolution, linearity, uniformity, and position resolution, using electron beams; To study the energy dependence of the response to electrons and hadrons to determine the particle identification capabilities of the EMCal by shower shape; And to investigate the timing characteristics of the energy signal for crude time-of-flight measurement ({approx} 1ns) for use for anti-neutron rejection. Measurements will be made for comparison with different signal shaping times in the front end electronics.

  14. [Health effects of electromagnetic fields].

    PubMed

    Rsli, Martin

    2013-12-01

    Use of electricity causes extremely low frequency magnetic fields (ELF-MF) and wireless communication devices emit radiofrequency electromagnetic fields (RF-EMF). Average ELF-MF exposure is mainly determined by high voltage power lines and transformers at home or at the workplace, whereas RF-EMF exposure is mainly caused by devices operating close to the body (mainly mobile and cordless phones). Health effects of EMF are controversially discussed. The IARC classified ELF-MF and RF-EMF as possible carcinogenic. Most consistent epidemiological evidence was found for an association between ELF-MF and childhood leukaemia. If causal, 1 - 4 percent of all childhood leukaemia cases could be attributed to ELF-MF. Epidemiological research provided some indications for an association between ELF-MF and Alzheimer's diseases as well as amyotrophic lateral sclerosis, although not entirely consistent. Regarding mobile phones and brain tumours, some studies observed an increased risk after heavy or long term use on the one hand. On the other hand, brain tumour incidence was not found to have increased in the last decade in Sweden, England or the US. Acute effects of RF-EMF on non-specific symptoms of ill health seem unlikely according to randomized and double blind provocation studies. However, epidemiological research on long term effects is still limited. Although from the current state of the scientific knowledge a large individual health risk from RF-EMF exposure is unlikely, even a small risk would have substantial public health relevance because of the widespread use of wireless communication technologies. PMID:24297859

  15. Is Electromagnetic Gravity Control Possible?

    NASA Astrophysics Data System (ADS)

    Vargas, Jose G.; Torr, Douglas G.

    2004-02-01

    We study the interplay of Einstein's Gravitation (GR) and Maxwell's Electromagnetism, where the distribution of energy-momentum is not presently known (The Feynman Lectures, Vol 2, Chapter 27, section 4). As Feynman himself stated, one might in principle use Einstein's equations of GR to find such a distribution. GR (born in 1915) presently uses the Levi-Civita connection, LCC (the LCC was born two years after GR as a new concept, and not just as the pre-existing Christoffel symbols that represent it). Around 1927, Einstein proposed for physics an alternative to the LCC that constitutes a far more sensible and powerful affine enrichment of metric Riemannian geometry. It is called teleparallelism (TP). Its Finslerian version (i.e. in the space-time-velocity arena) permits an unequivocal identification of the EM field as a geometric quantity. This in turn permits one to identify a completely geometric set of Einstein equations from curvature equations. From their right hand side, one may obtain the actual distribution of EM energy-momentum. It is consistent with Maxwell's equations, since these also are implied by the equations of structure of TP. We find that the so-far-unknown terms in this distribution amount to a total differential and do not, therefore, alter the value of the total EM energy-momentum. And yet these extra terms are at macroscopic distances enormously larger than the standard quadratic terms. This allows for the generation of measurable gravitational fields by EM fields. We thus answer affirmatively the question of the title.

  16. Is Electromagnetic Gravity Control Possible?

    SciTech Connect

    Vargas, Jose G.; Torr, Douglas G.

    2004-02-04

    We study the interplay of Einstein's Gravitation (GR) and Maxwell's Electromagnetism, where the distribution of energy-momentum is not presently known (The Feynman Lectures, Vol 2, Chapter 27, section 4). As Feynman himself stated, one might in principle use Einstein's equations of GR to find such a distribution. GR (born in 1915) presently uses the Levi-Civita connection, LCC (the LCC was born two years after GR as a new concept, and not just as the pre-existing Christoffel symbols that represent it). Around 1927, Einstein proposed for physics an alternative to the LCC that constitutes a far more sensible and powerful affine enrichment of metric Riemannian geometry. It is called teleparallelism (TP). Its Finslerian version (i.e. in the space-time-velocity arena) permits an unequivocal identification of the EM field as a geometric quantity. This in turn permits one to identify a completely geometric set of Einstein equations from curvature equations. From their right hand side, one may obtain the actual distribution of EM energy-momentum. It is consistent with Maxwell's equations, since these also are implied by the equations of structure of TP. We find that the so-far-unknown terms in this distribution amount to a total differential and do not, therefore, alter the value of the total EM energy-momentum. And yet these extra terms are at macroscopic distances enormously larger than the standard quadratic terms. This allows for the generation of measurable gravitational fields by EM fields. We thus answer affirmatively the question of the title.

  17. Mapping permafrost with airborne electromagnetics

    NASA Astrophysics Data System (ADS)

    Minsley, B. J.; Ball, L. B.; Bloss, B. R.; Kass, A.; Pastick, N.; Smith, B. D.; Voss, C. I.; Walsh, D. O.; Walvoord, M. A.; Wylie, B. K.

    2014-12-01

    Permafrost is a key characteristic of cold region landscapes, yet detailed assessments of how the subsurface distribution of permafrost impacts the environment, hydrologic systems, and infrastructure are lacking. Data acquired from several airborne electromagnetic (AEM) surveys in Alaska provide significant new insight into the spatial extent of permafrost over larger areas (hundreds to thousands of square kilometers) than can be mapped using ground-based geophysical methods or through drilling. We compare several AEM datasets from different areas of interior Alaska, and explore the capacity of these data to infer geologic structure, permafrost extent, and related hydrologic processes. We also assess the impact of fires on permafrost by comparing data from different burn years within similar geological environments. Ultimately, interpretations rely on understanding the relationship between electrical resistivity measured by AEM surveys and the physical properties of interest such as geology, permafrost, and unfrozen water content in the subsurface. These relationships are often ambiguous and non-unique, so additional information is useful for reducing uncertainty. Shallow (upper ~1m) permafrost and soil characteristics identified from remotely sensed imagery and field observations help to constrain and aerially extend near-surface AEM interpretations, where correlations between the AEM and remote sensing data are identified using empirical multivariate analyses. Surface nuclear magnetic resonance (sNMR) measurements quantify the contribution of unfrozen water at depth to the AEM-derived electrical resistivity models at several locations within one survey area. AEM surveys fill a critical data gap in the subsurface characterization of permafrost environments and will be valuable in future mapping and monitoring programs in cold regions.

  18. Electromagnetics for Detecting Shallow Tunnels

    NASA Astrophysics Data System (ADS)

    Won, I.

    2006-05-01

    Detecting tunnels by geophysical means, even very shallow ones, has been difficult, to say the least. Despite heavy R&D funding from the military since the early 70s, geophysicists have not produced tools that are simple and practical enough to meet the military needs. The initial interest and R&D funding on the subject perhaps started with the Vietcong tunnels in the 60s. Tunnels in the Korean DMZ, first found in the mid 70s, sharply escalated the R&D spending. During the 90s, covert tunnels along the US-Mexico border have kept the topic alive but at a minimal funding level. Most recent interest appears to be in the terrorism-related shallow tunnels, more or less anywhere in the regions of conflict. Despite the longstanding effort in the geophysical community under heavy public funding, there is a dearth of success stories where geophysicists can actually claim to have found hitherto unknown tunnels. For instance, geophysics has not discovered a single tunnel in Vietnam or in Korea! All tunnels across the Korean DMZ were found from human intelligence. The same is true to all illicit tunnels found along the southwestern border. The tunnels under discussion are clandestine, which implies that the people who built them do not wish others to succeed in finding them. The place around the tunnel, therefore, may not be the friendliest venue for surveyors to linger around. The situation requires tools that are fast, little noticeable, and hardly intrusive. Many geophysical sensors that require ground contacts, such as geophones and electrodes that are connected by a myriad of cables, may not be ideal in this situation. On the other hand, a sensor that can be carried by vehicle without stopping, and is nothing obviously noticeable to bystanders, could be much more acceptable. Working at unfriendly environment also requires forgoing our usual practices where we collect data leisurely and make pretty maps later. To be useful, geophysical tools must be able to process observed data and translate them into actionable results. They may in forms of audio (similar to the beeper of a landmine detector), strip chart, or even a 2D graphic display on a computer screen. In short, the tool must be able to declare a contact, audibly or graphically, in real time or shortly thereafter. In summary, we have two questions here. The first one is if any of the available geophysical tools can detect tunnels. If the answer is yes, then the next question is if any of them are able to perform fast in an unfriendly environment. Electromagnetic sensors may be able to meet the operational requirements: under what circumstances it can find tunnels would be another outstanding question.

  19. Power law inflation with electromagnetism

    SciTech Connect

    Luo, Xianghui; Isenberg, James

    2013-07-15

    We generalize Ringström’s global future causal stability results (Ringström 2009) [11] for certain expanding cosmological solutions of the Einstein-scalar field equations to solutions of the Einstein–Maxwell-scalar field system. In particular, after noting that the power law inflationary spacetimes (M{sup n+1},g{sup -hat}, ϕ{sup -hat}) considered by Ringström (2009) in [11] are solutions of the Einstein–Maxwell-scalar field system (with exponential potential) as well as of the Einstein-scalar field system (with the same exponential potential), we consider (nonlinear) perturbations of initial data sets of these spacetimes which include electromagnetic perturbations as well as gravitational and scalar perturbations. We show that if (as in Ringström (2009) [11]) we focus on pairs of relatively scaled open sets U{sub R{sub 0}}⊂U{sub 4R{sub 0}} on an initial slice of (M{sup n+1},g{sup -hat}), and if we choose a set of perturbed data which on U{sub 4R{sub 0}} is sufficiently close to that of (M{sup n+1},g{sup -hat},ϕ{sup -hat}, A{sup -hat} = 0), then in the maximal globally hyperbolic spacetime development (M{sup n+1},g,ϕ,A) of this data via the Einstein–Maxwell-scalar field equations, all causal geodesics emanating from U{sub R{sub 0}} are future complete (just as in (M{sup n+1},g{sup -hat})). We also verify that, in a certain sense, the future asymptotic behavior of the fields in the spacetime developments of the perturbed data sets does not differ significantly from the future asymptotic behavior of (M{sup n+1},g{sup -hat}, ϕ{sup -hat}, A{sup -hat} = 0). -- Highlights: •We prove stability of expanding solutions of the Einstein–Maxwell-scalar field equations. •All nearby solutions are geodesically complete. •The topology of the initial slice is irrelevant to our stability results.

  20. Nonholonomic catheter path reconstruction using electromagnetic tracking

    NASA Astrophysics Data System (ADS)

    Lugez, Elodie; Sadjadi, Hossein; Akl, Selim G.; Fichtinger, Gabor

    2015-03-01

    Catheter path reconstruction is a necessary step in many clinical procedures, such as cardiovascular interventions and high-dose-rate brachytherapy. To overcome limitations of standard imaging modalities, electromagnetic tracking has been employed to reconstruct catheter paths. However, tracking errors pose a challenge in accurate path reconstructions. We address this challenge by means of a filtering technique incorporating the electromagnetic measurements with the nonholonomic motion constraints of the sensor inside a catheter. The nonholonomic motion model of the sensor within the catheter and the electromagnetic measurement data were integrated using an extended Kalman filter. The performance of our proposed approach was experimentally evaluated using the Ascension's 3D Guidance trakStar electromagnetic tracker. Sensor measurements were recorded during insertions of an electromagnetic sensor (model 55) along ten predefined ground truth paths. Our method was implemented in MATLAB and applied to the measurement data. Our reconstruction results were compared to raw measurements as well as filtered measurements provided by the manufacturer. The mean of the root-mean-square (RMS) errors along the ten paths was 3.7 mm for the raw measurements, and 3.3 mm with manufacturer's filters. Our approach effectively reduced the mean RMS error to 2.7 mm. Compared to other filtering methods, our approach successfully improved the path reconstruction accuracy by exploiting the sensor's nonholonomic motion constraints in its formulation. Our approach seems promising for a variety of clinical procedures involving reconstruction of a catheter path.

  1. Magnetic flimmers: 'light in the electromagnetic darkness'.

    PubMed

    Martens, Johannes W; Koehler, Peter J; Vijselaar, Joost

    2013-03-01

    Transcranial magnetic stimulation has become an important field for both research in neuroscience and for therapy since Barker in 1985 showed that it was possible to stimulate the human motor cortex with an electromagnet. Today for instance, transcranial magnetic stimulation can be used to measure nerve conduction velocities and to create virtual lesions in the brain. The latter option creates the possibility to inactivate parts of the brain temporarily without permanent damage. In 2008, the American Food and Drugs Administration approved repetitive transcranial magnetic stimulation as a therapy for major depression under strict conditions. Repetitive transcranial magnetic stimulation has not yet been cleared for treatment of other diseases, including schizophrenia, anxiety disorders, obesity and Parkinson's disease, but results seem promising. Transcranial magnetic stimulation, however, was not invented at the end of the 20th century. The discovery of electromagnetism, the enthusiasm for electricity and electrotherapy, and the interest in Beard's concept of neurasthenia already resulted in the first electromagnetic treatments in the late 19th and early 20th century. In this article, we provide a history of electromagnetic stimulation circa 1900. From the data, we conclude that Mesmer's late 18th century ideas of 'animal magnetism' and the 19th century absence of physiological proof had a negative influence on the acceptance of this therapy during the first decades of the 20th century. Electromagnetism disappeared from neurological textbooks in the early 20th century to recur at the end of that century. PMID:23043145

  2. Performance analysis of superconducting generator electromagnetic shielding

    NASA Astrophysics Data System (ADS)

    Xia, D.; Xia, Z.

    2015-12-01

    In this paper, the shielding performance of electromagnetic shielding systems is analyzed using the finite element method. Considering the non-iron-core rotor structure of superconducting generators, it is proposed that the stator alternating magnetic field generated under different operating conditions could decompose into oscillating and rotating magnetic field, so that complex issues could be greatly simplified. A 1200KW superconducting generator was analyzed. The distribution of the oscillating magnetic field and the rotating magnetic field in rotor area, which are generated by stator winding currents, and the distribution of the eddy currents in electromagnetic shielding tube, which are induced by these stator winding magnetic fields, are calculated without electromagnetic shielding system and with three different structures of electromagnetic shielding system respectively. On the basis of the results of FEM, the shielding factor of the electromagnetic shielding systems is calculated and the shielding effect of the three different structures on the oscillating magnetic field and the rotating magnetic field is compared. The method and the results in this paper can provide reference for optimal design and loss calculation of superconducting generators.

  3. Electromagnetic currents induced by color fields

    NASA Astrophysics Data System (ADS)

    Tanji, Naoto

    2015-12-01

    The quark production in classical color fields is investigated with a focus on the induction of an electromagnetic current by produced quarks. We show that the color SU(2) and the SU(3) theories lead significantly different results for the electromagnetic current. In uniform SU(2) color fields, the net electromagnetic current is not generated, while in SU(3) color fields the net current is induced depending on the color direction of background fields. Also the numerical study of the quark production in inhomogeneous color fields is done. Motivated by gauge field configurations provided by the color glass condensate framework, we introduce an ensemble of randomly distributed color electric fluxtubes. The spectrum of photons emitted from the quarks by a classical process is shown.

  4. The ELF-I augmented electromagnetic launcher

    NASA Astrophysics Data System (ADS)

    Fikse, D. A.; Wu, J. L.; Thio, Y. C.

    1984-03-01

    Augmenting an electromagnetic launcher barrel with one or more turns can theoretically increase the launcher system performance more than twice that of a simple EML. This is accomplished by increasing the amount of magnetic flux in the bore and thus increasing the electromagnetic accelerating force. The potential for augmented barrels had yet to be evaluated, therefore a one meter long test barrel was designed and constructed. This barrel was tested in the ELF-I electromagnetic test facility and the results compared with the theoretically predicted performance of a simple barrel design. This comparison shows an increase in muzzle velocity of 83 percent for the augmented case over the simple launcher case. It was also found that the augmented barrel could be fabricated in a simple manner within the physical limitations of a conventional barrel size, and that its solid armatures provided an excellent method of achieving longer rail life, averaging 20 shots per rail set.

  5. Dynamics of a Nonlinear Electromagnetic System

    NASA Astrophysics Data System (ADS)

    Chang, Shun-Chang; Tung, Pi-Cheng

    1999-04-01

    An experiment with a test rig consisting of a symmetric rotor suspended bya spring device and excited by a series of nonlinear electromagnetic forces hasbeen performed by Chang and Tung [Sound & Vib. 214 (1998) 853], to investigate the effects of an electromagnet processing highly nonlinearcharacteristics on general mechanical systems. A nonlinear mathematical modelhas been obtained by applying a modified conventional identification techniquebased on the principle of harmonic balance. In this study, analytical work iscarried out on this identified nonlinear model by applying the first-harmonicapproximation solution and the Floquet theory. The resulting criteria forbifurcations can be used to evaluate the operational range of a systememploying such a nonlinear actuator. We also employ the method of Lyapunovexponents to show the occurrence of chaotic motion and to verify the aboveanalyses. A comparison of the analytical results with those of the experimemtshows that the identified nonlinear model obtained from the experiment canpredict and characterize the dynamics of a real electromagnetic system.

  6. Alternative Expression for the Electromagnetic Lagrangian

    NASA Astrophysics Data System (ADS)

    Saldanha, Pablo L.

    2016-04-01

    We reintroduce an alternative expression for the Lagrangian density that governs the interaction of a charged particle with external electromagnetic fields, proposed by Livens about one century ago. This Lagrangian is written in terms of the local superposition of the particle fields with the applied electromagnetic fields, not in terms of the particle charge and of the electromagnetic potentials as is usual. Here, we show that the total Lagrangian for a set of charged particles assumes a simple elegant form with the alternative formulation, giving an aesthetic support for it. We also show that the alternative Lagrangian is equivalent to the traditional one in their domain of validity and that it provides an interesting description of the Aharonov-Bohm effect.

  7. Electromagnetically driven dwarf tornados in turbulent convection

    NASA Astrophysics Data System (ADS)

    Kenjereš, Saša

    2011-01-01

    Motivated by the concept of interdependency of turbulent flow and electromagnetic fields inside the spiraling galaxies, we explored the possibilities of generating a localized Lorentz force that will produce a three-dimensional swirling flow in weakly conductive fluids. Multiple vortical flow patterns were generated by combining arrays of permanent magnets and electrodes with supplied dc current. This concept was numerically simulated and applied to affect natural convection flow, turbulence, and heat transfer inside a rectangular enclosure heated from below and cooled from above over a range of Rayleigh numbers (104<=Ra<=5×109). The large-eddy simulations revealed that for low- and intermediate-values of Ra, the heat transfer was increased more than five times when an electromagnetic forcing was activated. In contrast to the generally accepted view that electromagnetic forcing will suppress velocity fluctuations and will increase anisotropy of turbulence, we demonstrated that localized forcing can enhance turbulence isotropy of thermal convection compared to its neutral state.

  8. Drift effects on electromagnetic geodesic acoustic modes

    NASA Astrophysics Data System (ADS)

    Sgalla, R. J. F.

    2015-02-01

    A two fluid model with parallel viscosity is employed to derive the dispersion relation for electromagnetic geodesic acoustic modes (GAMs) in the presence of drift (diamagnetic) effects. Concerning the influence of the electron dynamics on the high frequency GAM, it is shown that the frequency of the electromagnetic GAM is independent of the equilibrium parallel current but, in contrast with purely electrostatic GAMs, significantly depends on the electron temperature gradient. The electromagnetic GAM may explain the discrepancy between the f ˜ 40 kHz oscillation observed in tokamak TCABR [Yu. K. Kuznetsov et al., Nucl. Fusion 52, 063044 (2012)] and the former prediction for the electrostatic GAM frequency. The radial wave length associated with this oscillation, estimated presently from this analytical model, is λr ˜ 25 cm, i.e., an order of magnitude higher than the usual value for zonal flows (ZFs).

  9. Feedback Control for Electromagnetic Vibration Feeder

    NASA Astrophysics Data System (ADS)

    Doi, Tomoharu; Yoshida, Koji; Tamai, Yutaka; Kono, Katsuaki; Naito, Kazufumi; Ono, Toshiro

    An electromagnetic-type vibratory feeder of is a typical transportation device used in automatic weighers. As existing feeders are driven by feedforward control, the so-called firing angle control, the driver cannot negate sudden disturbances. In this study, we consider applying a feedback control for such a feeder system. First, we give the two details of modelings for the vibration part and for the electromagnetic force part. Next, a feedback control system is constructed for the electromagnetic vibration feeder for which we propose a two-degrees-of-freedom proportional plus integral plus derivative (PID) controller with nonlinear elements. Next, we apply the feedback control to the feeder with a standard trough. Finally, we consider a method compatible with many varieties of troughs by adjusting a nonlinear element. On the basis of the results of some experiments, we confirm that the two-degrees-of-freedom PID control is more effective than the conventional firing angle control.

  10. An Introduction to Classical Electromagnetic Radiation

    NASA Astrophysics Data System (ADS)

    Smith, Glenn S.

    1997-08-01

    A fundamental and thorough description of classical electromagnetic radiation, this book is a balance of physical and mathematical explanation and includes over 300 illustrations. Starting from Maxwell's equations, the author demonstrates how fundamental concepts are applied in a wide variety of examples from areas such as classical optics, antenna analysis, and electromagnetic scattering. An interweaving of theoretical and experimental results gives insight into the physical and historical foundations of the subject. The book gives equal footing to the radiation of pulses and the more conventional time harmonic signals. With more than 140 problems, it can be used as a textbook for advanced undergraduate and graduate courses in electrical engineering and physics, and will also be of interest to scientists and engineers working in applied electromagnetics. A solutions manual is available for instructors.

  11. Broadband electromagnetic cloaking with smart metamaterials.

    PubMed

    Shin, Dongheok; Urzhumov, Yaroslav; Jung, Youngjean; Kang, Gumin; Baek, Seunghwa; Choi, Minjung; Park, Haesung; Kim, Kyoungsik; Smith, David R

    2012-01-01

    The ability to render objects invisible with a cloak that fits all objects and sizes is a long-standing goal for optical devices. Invisibility devices demonstrated so far typically comprise a rigid structure wrapped around an object to which it is fitted. Here we demonstrate smart metamaterial cloaking, wherein the metamaterial device not only transforms electromagnetic fields to make an object invisible, but also acquires its properties automatically from its own elastic deformation. The demonstrated device is a ground-plane microwave cloak composed of an elastic metamaterial with a broad operational band (10-12 GHz) and nearly lossless electromagnetic properties. The metamaterial is uniform, or perfectly periodic, in its undeformed state and acquires the necessary gradient-index profile, mimicking a quasi-conformal transformation, naturally from a boundary load. This easy-to-fabricate hybrid elasto-electromagnetic metamaterial opens the door to implementations of a variety of transformation optics devices based on quasi-conformal maps. PMID:23169054

  12. Electromagnetic wave propagation characteristics in unimolecular reactions

    NASA Astrophysics Data System (ADS)

    Liu, Xingpeng; Huang, Kama

    2016-01-01

    Microwave-assisted chemical reactions have attracted interests because of their benefits for enhancement of reaction rates. However, the problems, such as hot spots and thermal runaway, limit the application of microwaves in the chemical industry. To study the characteristics of electromagnetic wave propagation in a chemical reaction is critical to solve the problems. The research on the characteristics of electromagnetic wave propagation in the unimolecular reaction that is a simple model reaction, can be generalized to the research in a chemical reaction. The approximate expressions of the attenuation and dispersion characteristics of electromagnetic wave propagation in the unimolecular reaction are derived by the nonlinear propagation theory. Specially, when the reaction rate is zero, the derived approximate expressions can be reduced to the formulas in low-loss dispersive media. Moreover, a 1D mold is used to validate the feasibility of the approximate expressions. The influences of the reaction rate and initial reactant concentration on the characteristics are obtained.

  13. Advanced electromagnetic methods for aerospace vehicles

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  14. Apparatus for processing electromagnetic radiation and method

    NASA Technical Reports Server (NTRS)

    Gatewood, George D. (Inventor)

    1983-01-01

    Measuring apparatus including a ruled member having alternate transparent and opaque zones. An optical coupler connecting the ruled member with electromagnetic radiation-conversion apparatus. The conversion apparatus may include a photomultiplier and a discriminator. Radiation impinging on the ruled member will, in part, be converted to electrical pulses which correspond to the intensity of the radiation. A method of processing electromagnetic radiation includes providing a member having alternating dark and light zones, establishing movement of the member through the beam of electromagnetic radiation with the dark zones interrupting passage of radiation through the rule, providing an optical coupler to connect a portion of the radiation with a conversion station where the radiation portion is converted into an electrical pulse which is related to the intensity of the radiation received at the conversion station. The electrical pulses may be counted and the digitized signals stored or permanently recorded to produce positional information.

  15. Electromagnetic energy momentum in dispersive media

    SciTech Connect

    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 are 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.

  16. Electromagnetically induced absorption via incoherent collisions

    SciTech Connect

    Yang Xihua; Sheng Jiteng; Xiao Min

    2011-10-15

    We conduct theoretical studies on electromagnetically induced absorption via incoherent collisions in an inhomogeneously broadened ladder-type three-level system with the density-matrix approach. The effects of the collision-induced coherence decay rates as well as the probe laser field intensity on the probe field absorption are examined. It is shown that with the increase of the collisional decay rates in a moderate range, a narrow dip due to electromagnetically induced transparency superimposed on the Doppler-broadened absorption background can be turned into a narrow peak under the conditions that the probe field intensity is not very weak as compared to the pump field, which results from the enhancement of constructive interference and suppression of destructive interference between one-photon and multiphoton transition pathways. The physical origin of the collision-assisted electromagnetically induced absorption is analyzed with a power-series solution of the density-matrix equations.

  17. Gallium Electromagnetic (GEM) Thrustor Concept and Design

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Markusic, Thomas E.

    2006-01-01

    We describe the design of a new type of two-stage pulsed electromagnetic accelerator, the gallium electromagnetic (GEM) thruster. A schematic illustration of the GEM thruster concept is given in Fig. 1. In this concept, liquid gallium propellant is pumped into the first stage through a porous metal electrode using an electromagneticpump[l]. At a designated time, a pulsed discharge (approx.10-50 J) is initiated in the first stage, ablating the liquid gallium from the porous electrode surface and ejecting a dense thermal gallium plasma into the second state. The presence of the gallium plasma in the second stage serves to trigger the high-energy (approx.500 I), send-stage puke which provides the primary electromagnetic (j x B) acceleration.

  18. Drift effects on electromagnetic geodesic acoustic modes

    SciTech Connect

    Sgalla, R. J. F.

    2015-02-15

    A two fluid model with parallel viscosity is employed to derive the dispersion relation for electromagnetic geodesic acoustic modes (GAMs) in the presence of drift (diamagnetic) effects. Concerning the influence of the electron dynamics on the high frequency GAM, it is shown that the frequency of the electromagnetic GAM is independent of the equilibrium parallel current but, in contrast with purely electrostatic GAMs, significantly depends on the electron temperature gradient. The electromagnetic GAM may explain the discrepancy between the f ∼ 40 kHz oscillation observed in tokamak TCABR [Yu. K. Kuznetsov et al., Nucl. Fusion 52, 063044 (2012)] and the former prediction for the electrostatic GAM frequency. The radial wave length associated with this oscillation, estimated presently from this analytical model, is λ{sub r} ∼ 25 cm, i.e., an order of magnitude higher than the usual value for zonal flows (ZFs)

  19. Electromagnetic PIC modeling with a background gas

    NASA Astrophysics Data System (ADS)

    Verboncoeur, J. P.; Cooperberg, D.

    1997-02-01

    Modeling the interaction of relativistic electromagnetic plasmas with a background gas is described. The timescales range over many orders of magnitude, from the electromagnetic Courant condition (˜10-12 sec) to electron-neutral collision times (˜10-7 sec) to ion transit times (˜10-5 sec). For this work, the traditional Monte Carlo algorithm [1] is described for relativistic electrons. Subcycling is employed to improve efficiency, and smoothing is employed to reduce particle noise. Applications include plasma-focused electron guns, gas-filled microwave tubes, surface wave discharges driven at microwave frequencies, and electron-cyclotron resonance discharges. The method is implemented in the OOPIC code [2].

  20. Electromagnetic PIC modeling with a background gas

    SciTech Connect

    Verboncoeur, J. P.; Cooperberg, D.

    1997-02-01

    Modeling the interaction of relativistic electromagnetic plasmas with a background gas is described. The timescales range over many orders of magnitude, from the electromagnetic Courant condition ({approx}10{sup -12} sec) to electron-neutral collision times ({approx}10{sup -7} sec) to ion transit times ({approx}10{sup -5} sec). For this work, the traditional Monte Carlo algorithm [1] is described for relativistic electrons. Subcycling is employed to improve efficiency, and smoothing is employed to reduce particle noise. Applications include plasma-focused electron guns, gas-filled microwave tubes, surface wave discharges driven at microwave frequencies, and electron-cyclotron resonance discharges. The method is implemented in the OOPIC code [2].

  1. Phenomenology of the deuteron electromagnetic form factors

    SciTech Connect

    David Abbott; Abdellah Ahmidouch; H. Anklin; J. Arvieux; James P. Ball; Shelton Beedoe; Elizabeth Beise; Louis Bimbot; Werner Boeglin; Herbert Breuer; Roger Carlini; Nicholas Chant; Samuel Danagoulian; K. Dow; Jean-Eric Ducret; Jim Dunne; Lars Ewell; L. Eyraud; C. Furget; Michel Garcon; Ron Gilman; Charles Glashausser; Paul Gueye; Kenneth Gustafsson; Kawtar Hafidi; A. Honegger; J. Jourdan; Serge Kox; Gerfried Kumbartzki; L. Lu; Allison Lung; Pete Markowitz; Justin McIntyre; David Meekins; F. Merchez; Joseph Mitchell; R. Mohring; S. Mtingwa; H. Mrktchyan; D. Pitz; Liming Qin; Ronald Ransome; J.-S. R'eal; Philip Roos; Paul Rutt; Reyad Sawafta; Stepan Stepanyan; Raphael Tieulent; E. Tomasi-Gustafsson; William Turchinetz; K. Vansyoc; J. Volmer; E. Voutier; Claude Williamson; Stephen Wood; Chen Yan; Jianguo Zhao; W. Zhao

    2000-02-25

    A rigorous extraction of the deuteron charge form factors from tensor polarization data in elastic electron-deuteron scattering, at given values of the 4-momentum transfer, is presented. Then the world data for elastic electron-deuteron scattering is used to parameterize, in three different ways, the three electromagnetic form factors of the deuteron in the 4-momentum transfer range 0-7 fm. This procedure is made possible with the advent of recent polarization measurements. The parameterizations allow a phenomenological characterization of the deuteron electromagnetic structure. They can be used to remove ambiguities in the form factors extraction from future polarization data.

  2. Phenomenology of the deuteron electromagnetic form factors

    SciTech Connect

    David Abbott; Abdellah Ahmidouch; H. Anklin; J. Arvieux; James P. Ball; Shelton Beedoe; Elizabeth Beise; Louis Bimbot; Werner Boeglin; Herbert Breuer; Roger Carlini; Nicholas Chant; Samuel Danagoulian; K. Dow; Jean-Eric Ducret; Jim Dunne; Lars Ewell; L. Eyraud; C. Furget; Michel Garcon; Ron Gilman; Charles Glashausser; Paul Gueye; Kenneth Gustafsson; Kawtar Hafidi; A. Honegger; J. Jourdan; Serge Kox; Gerfried Kumbartzki; L. Lu; Allison Lung; Pete Markowitz; Justin McIntyre; David Meekins; F. Merchez; Joseph Mitchell; R. Mohring; S. Mtingwa; H. Mrktchyan; D. Pitz; Liming Qin; Ronald Ransome; J.-S. R'eal; Philip Roos; Paul Rutt; Reyad Sawafta; Stepan Stepanyan; Raphael Tieulent; E. Tomasi-Gustafsson; William Turchinetz; K. Vansyoc; J. Volmer; E. Voutier; Claude Williamson; Stephen Wood; Chen Yan; Jianguo Zhao; W. Zhao

    2000-04-01

    A rigorous extraction of the deuteron charge form factors from tensor polarization data in elastic electron-deuteron scattering, at given values of the 4-momentum transfer, is presented. Then the world data for elastic electron-deuteron scattering is used to parameterize, in three different ways, the three electromagnetic form factors of the deuteron in the 4-momentum transfer range 0-7 fm. This procedure is made possible with the advent of recent polarization measurements. The parameterizations allow a phenomenological characterization of the deuteron electromagnetic structure. They can be used to remove ambiguities in the form factors extraction from future polarization data.

  3. [Electromagnetic Shielding Alters Behaviour of Rats].

    PubMed

    Temuryants, N A; Kostyuk, A S; Tumanyants, K N

    2015-01-01

    It has been found that long-term electromagnetic shielding (19 hours per day for 10 days) leads to an increase in the duration of passive swimming time in male rats, decrease the duration of active swimming in the "forced swim" test as well as decrease of libido. On the other hand animals kept under the "open field" conditions do not show significant deviations from their normal behavior. Therefore, one could conclude that moderate electromagnetic shielding causes a depression-like state in rats. PMID:26080600

  4. Wavelets and electromagnetic power system transients

    SciTech Connect

    Robertson, D.C.; Camps, O.I.; Mayer, J.S.; Gish, W.B.

    1996-04-01

    The wavelet transform is introduced as a method for analyzing electromagnetic transients associated with power system faults and switching. This method, like the fourier transform, provides information related to the frequency composition of a waveform, but it is more appropriate than the familiar Fourier methods for the non-periodic, wide-band signals associated with electromagnetic transients. It appears that the frequency domain data produced by the wavelet transform may be useful for analyzing the sources of transients through manual or automated feature detection schemes. The basic principles of wavelet analysis are set forth, and examples showing the application of the wavelet transform to actual power system transients are presented.

  5. Hawking radiation in an electromagnetic waveguide?

    PubMed

    Schützhold, Ralf; Unruh, William G

    2005-07-15

    It is demonstrated that the propagation of electromagnetic waves in an appropriately designed waveguide is (for large wavelengths) analogous to that within a curved space-time--such as around a black hole. As electromagnetic radiation (e.g., microwaves) can be controlled, amplified, and detected (with present-day technology) much easier than sound, for example, we propose a setup for the experimental verification of the Hawking effect. Apart from experimentally testing this striking prediction, this would facilitate the investigation of the trans-Planckian problem. PMID:16090733

  6. Axial electromagnetic force density in MPD thrusters

    SciTech Connect

    Sheshadri, T.S. )

    1992-10-10

    In this paper an MPD thruster formulation involving coupled aerothermodynamic-electromagnetic equations and including viscous effects is developed and solved. The electromagnetic force density distribution in the thruster interior is studied. Axial force densities are fount to be largest on the cathode longitudinal surface. Very large force densities are found at the cathode upstream end and this is attributed to large values of the Hall parameter. Over the rest of the cathode longitudinal surface, axial force densities increase with increasing inlet velocities and mass densities and large plasma viscosities. Equivalent increases in inlet velocity and mass density produce effects of different magnitudes.

  7. Nonlinear Electromagnetic Interactions in Energetic Materials

    NASA Astrophysics Data System (ADS)

    Wood, M. A.; Dalvit, D. A. R.; Moore, D. S.

    2016-01-01

    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. 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.

  8. Scanning evanescent electro-magnetic microscope

    DOEpatents

    Xiang, Xiao-Dong; Gao, Chen

    2001-01-01

    A novel scanning microscope is described that uses near-field evanescent electromagnetic waves to probe sample properties. The novel microscope is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The inventive scanning evanescent wave electromagnetic microscope (SEMM) can map dielectric constant, tangent loss, conductivity, complex electrical impedance, and other electrical parameters of materials. The quantitative map corresponds to the imaged detail. The novel microscope can be used to measure electrical properties of both dielectric and electrically conducting materials.

  9. Scanning evanescent electro-magnetic microscope

    DOEpatents

    Xiang, Xiao-Dong; Gao, Chen; Schultz, Peter G.; Wei, Tao

    2003-01-01

    A novel scanning microscope is described that uses near-field evanescent electromagnetic waves to probe sample properties. The novel microscope is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The inventive scanning evanescent wave electromagnetic microscope (SEMM) can map dielectric constant, tangent loss, conductivity, complex electrical impedance, and other electrical parameters of materials. The quantitative map corresponds to the imaged detail. The novel microscope can be used to measure electrical properties of both dielectric and electrically conducting materials.

  10. Canonical aberration theory in electromagnetic multipoles

    NASA Astrophysics Data System (ADS)

    Ximen, Jiye

    1990-12-01

    In a 2N-pole electromagnetic system, defining the electron optical Hamiltonian function, we have derived both general algebraic expressions (arbitrary N) and special numerical formulas (N=3,4,5,6,7) for different aberrations from lower to higher order (i.e., the order of N-1, N+1, 2N-3, 2N-1, 3N-5). The so-called canonical aberration theory in electromagnetic multipoles has thus been developed, which allows us to deduce angular dependencies of different aberrations and to examine the possibility for spherical correction of a round lens by using multipoles.

  11. Electromagnetic continuous casting project: Final report

    SciTech Connect

    Battles, J.E.; Rote, D.M.; Misra, B.; Praeg, W.F.; Hull, J.R.; Turner, L.R.; Shah, V.L.; Lari, R.J.; Gopalsami, N.; Wiencek, T.

    1988-10-01

    This report describes the work on development of an electromagnetic casting process for steel, which was carried out at Argonne National Laboratory between January 1985 and December 1987. This effort was concerned principally with analysis and design work on magnet technology, liquid metal feed system, coolant system, and sensors and process controllers. Experimentation primarily involved (1) electromagnetic studies to determine the conditions and controlling parameters for stable levitation and (2) feed-system studies to establish important parameters that control and influence fluid flow from the liquid metal source to the caster. 73 refs., 91 figs., 11 tabs.

  12. Microfabricated electromagnetic filters for millikelvin experiments

    NASA Astrophysics Data System (ADS)

    le Sueur, Hélène; Joyez, Philippe

    2006-11-01

    In this article we report on the design, fabrication, and tests of microfabricated broadband filters suitable for proper electromagnetic thermalization of electrical lines connected to sensitive quantum electronics experiments performed at dilution fridge temperatures. Compared to previous such miniature filters, the new design improves on performance and reliability. These filters can be packed in space-saving cases with either single or multicontact connector. Measured performance in the accessible range compares well to simulations. We use these simulations to discuss the effectiveness of these filters for electromagnetic thermalization at 30mK.

  13. Parametrically shielding electromagnetic fields by nonlinear metamaterials.

    PubMed

    Feng, Simin; Halterman, Klaus

    2008-02-15

    An analytical theory is developed for parametric interactions in metamaterial multilayer structures with simultaneous nonlinear electronic and magnetic responses and with a near-zero refractive index. We demonstrate theoretically that electromagnetic fields of certain frequencies can be parametrically shielded by a nonlinear left-handed material slab, where the permittivity and permeability are both negative. The skin depth is tunable, and even in the absence of material absorption, can be much less than the wavelength of the electromagnetic field being shielded. This exotic behavior is a consequence of the intricate nonlinear response in the left-handed materials and vanishing optical refractive index at the pump frequency. PMID:18352472

  14. Excitation of surface electromagnetic waves on water.

    PubMed

    Singh, A K; Goben, C A; Davarpanah, M; Boone, J L

    1978-11-01

    Excitation of surface electromagnetic waves (SEW) on water was studied using optical coupling techniques at microwave frequencies. Excitation of SEW was also achieved using direct horn antenna coupling. The transmitted SEW power was increased by adding acid and salt to water. The horn antenna gave the maximum excitation efficiency 70%. It was increased to 75% by collimating the electromagnetic beam in the vertical direction. Excitation efficiency for the prism (0 degrees pitch angle) and grating couplers were 15.2% and 10.5% respectively. By changing the prism coupler pitch angle to +36 degrees , its excitation efficiency was increased to 82%. PMID:20204001

  15. Device and method for redirecting electromagnetic signals

    DOEpatents

    Garcia, Ernest J.

    1999-01-01

    A device fabricated to redirect electromagnetic signals, the device including a primary driver adapted to provide a predetermined force, a linkage system coupled to the primary driver, a pusher rod rotationally coupled to the linkage system, a flexible rod element attached to the pusher rod and adapted to buckle upon the application of the predetermined force, and a mirror structure attached to the flexible rod element at one end and to the substrate at another end. When the predetermined force buckles the flexible rod element, the mirror structure and the flexible rod element both move to thereby allow a remotely-located electromagnetic signal directed towards the device to be redirected.

  16. NASA GRC High Power Electromagnetic Thruster Program

    NASA Technical Reports Server (NTRS)

    LaPointe, Michael R.; Pensil, Eric J.

    2004-01-01

    High-power electromagnetic thrusters have been proposed as primary in-space propulsion options for several bold new interplanetary and deep-space missions. As the lead center for electric propulsion, the NASA Glenn Research Center designs, develops, and tests high-power electromagnetic technologies to meet these demanding mission requirements. Two high-power thruster concepts currently under investigation by Glenn are the magnetoplasmadynamic (MPD) thruster and the Pulsed Inductive Thruster (PIT). This paper describes the MPD thruster and the test facility.

  17. Electromagnetic effects on toroidal momentum transport

    SciTech Connect

    Mahmood, M. Ansar; Eriksson, A.; Weiland, J.

    2010-12-15

    A parametric study of electromagnetic effects on toroidal momentum transport has been performed. The work is based on a new version of the Weiland model where symmetry breaking toroidicity effects derived from the stress tensor have been taken into account. The model includes a self-consistent calculation of the toroidal momentum diffusivity, which contains both diagonal and off-diagonal contributions to the momentum flux. It is found that electromagnetic effects considerably increase the toroidal momentum pinch. They are sometimes strong enough to make the total toroidal momentum flux inward.

  18. Linear Electromagnetic Acutator With Manual Override

    NASA Technical Reports Server (NTRS)

    Abel, Stephen G.

    1994-01-01

    Conceptual permanent-magnet-assisted electromagnetic linear actuator used to set axial position of metering component in valve. One notable feature of actuator is external pole-piece subassembly that swivels manually about axis of linear motion (which is also axis of cylindrical symmetry) to vary distribution of magnetic flux in such way as to override electrical position control. Armature and magnets hermetically sealed.

  19. Project Physics Text 4, Light and Electromagnetism.

    ERIC Educational Resources Information Center

    Harvard Univ., Cambridge, MA. Harvard Project Physics.

    Optical and electromagnetic fundamentals are presented in this fourth unit of the Project Physics text for use by senior high students. Development of the wave theory in the first half of the 19th Century is described to deal with optical problems at the early stage. Following explanations of electric charges and forces, field concepts are…

  20. Alternating current electromagnetic servo induction meter

    NASA Technical Reports Server (NTRS)

    Bogue, R. K.

    1968-01-01

    Electromagnetic device accurately indicates the responses of various sensors in high performance flight research aircraft to conditions encountered in flight. The device responds to sensor inputs to move a slideable armature along an indicator scale by the force of currents induced in the armature winding.

  1. Approximate analysis of electromagnetically coupled microstrip dipoles

    NASA Astrophysics Data System (ADS)

    Kominami, M.; Yakuwa, N.; Kusaka, H.

    1990-10-01

    A new dynamic analysis model for analyzing electromagnetically coupled (EMC) microstrip dipoles is proposed. The formulation is based on an approximate treatment of the dielectric substrate. Calculations of the equivalent impedance of two different EMC dipole configurations are compared with measured data and full-wave solutions. The agreement is very good.

  2. Electromagnetic Force on a Moving Dipole

    ERIC Educational Resources Information Center

    Kholmetskii, Alexander L.; Missevitch, Oleg V.; Yarman, T.

    2011-01-01

    We analyse the force acting on a moving dipole due to an external electromagnetic field and show that the expression derived in Vekstein (1997 "Eur. J. Phys." 18 113) is erroneous and suggest the correct equation for the description of this force. We also discuss the physical meaning of the relativistic transformation of current for a closed…

  3. Electromagnetic field interactions with biological systems

    SciTech Connect

    Frey, A.H. )

    1993-02-01

    This is a report on Symposia organized by the International Society for Bioelectricity and presented at the 1992 FASEB Meeting. The presentations summarized here were intended to provide a sampling of new and fruitful lines of research. The theme topics for the Symposia were cancer, neural function, cell signaling, pineal gland function, and immune system interactions. Living organisms are complex electrochemical systems that evolved over billions of years in a world with a relatively simple weak magnetic field and with few electromagnetic energy emitters. As is characteristic of living organisms, they interacted with and adapted to this environment of electric and magnetic fields. In recent years there has been a massive introduction of equipment that emits electromagnetic fields in an enormous range of new frequencies, modulations, and intensities. As living organisms have only recently found themselves immersed in this new and virtually ubiquitous environment, they have not had the opportunity to adapt to it. This gives biologists the opportunity to use these electromagnetic fields as probes to study the functioning of living systems. This is a significant opportunity, as new approaches to studying living systems so often provide the means to make great leaps in science. In recent years, a diversity of biologists have carried out experiments using electromagnetic fields to study the function of living cells and systems. This approach is now becoming quite fruitful and is yielding data that are advancing our knowledge in diverse areas of biology. 25 refs., 6 figs., 3 tabs.

  4. Electromagnetic compatibility design guideline for STADAN

    NASA Technical Reports Server (NTRS)

    Cowdell, R. B.; Hill, J. S.; Senn, J. C.; Shifman, J. C.; Skaggs, J. W.

    1971-01-01

    Procedures for achieving electromagnetic compatibility in electronic and electrical equipment for aerospace ground stations are investigated. The application of shielding theory to good design is treated and standards of good practice are outlined for bonding, grounding, wiring, and cabling. Some aspects of filter design are explained, and suggestions are given for the application of filters to electronic and electrical equipment.

  5. Maxwell's electromagnetic theory and special relativity.

    PubMed

    Hall, Graham

    2008-05-28

    This paper presents a brief history of electromagnetic theory from ancient times up to the work of Maxwell and the advent of Einstein's special theory of relativity. It is divided into five convenient periods and the intention is to describe these developments for the benefit of a lay scientific audience and with the minimum of technical detail. PMID:18218598

  6. Accuracy Assessment for AG500, Electromagnetic Articulograph

    ERIC Educational Resources Information Center

    Yunusova, Yana; Green, Jordan R.; Mefferd, Antje

    2009-01-01

    Purpose: The goal of this article was to evaluate the accuracy and reliability of the AG500 (Carstens Medizinelectronik, Lenglern, Germany), an electromagnetic device developed recently to register articulatory movements in three dimensions. This technology seems to have unprecedented capabilities to provide rich information about time-varying…

  7. Electromagnetic driving units for complex microrobotic systems

    NASA Astrophysics Data System (ADS)

    Michel, Frank; Ehrfeld, Wolfgang; Berg, Udo; Degen, Reinhard; Schmitz, Felix

    1998-10-01

    Electromagnetic actuators play an important role in macroscopic robotic systems. In combination with motion transformers, like reducing gear units, angular gears or spindle-screw drives, electromagnetic motors in large product lines ensure the rotational or linear motion of robot driving units and grippers while electromagnets drive valves or part conveyors. In this paper micro actuators and miniaturized motion transformers are introduced which allow a similar development in microrobotics. An electromagnetic motor and a planetary gear box, both with a diameter of 1.9 mm, are already commercially available from the cooperation partner of IMM, the company Dr. Fritz Faulhaber GmbH in Schonaich, Germany. In addition, a motor with a diameter of 2.4 mm is in development. The motors successfully drive an angular gear and a belt drive. A linear stage with a motion range of 7 mm and an overall size as small as 5 X 3.5 X 24 mm3 has been realized involving the motor, a stationary spur gear with zero backlash and a spindle-screw drive. By the use of these commercially available elements complex microrobots can be built up cost-efficiently and rapidly. Furthermore, a batch process has been developed to produce the coils of micro actuator arrays using lithographic techniques with SU-8 resin. In applying these components, the modular construction of complex microrobotic systems becomes feasible.

  8. Electromagnetic fields in bone repair and adaptation

    NASA Astrophysics Data System (ADS)

    McLeod, Kenneth J.; Rubin, Clinton T.; Donahue, Henry J.

    1995-01-01

    The treatment of delayed union of bone fractures has served for the past 20 years as the principal testing ground for determining whether nonionizing electromagnetic fields can have any substantial, long-term effects in clinical medicine. Recent double-blinded clinical trials have confirmed the significance of the reported effects on bone healing and have led to the suggestion that electromagnetic fields may also be useful in the treatment of other orthopedic problems such as fresh fractures, stabilization of prosthetic implants, or even the prevention or treatment of osteoporosis. However, the design of appropriate treatment regimens for these new applications would be greatly facilitated if it were understood how the biological cells within bone tissue sense these low-frequency, and remarkably low level, electromagnetic fields. Here we address the engineering and physical science aspects of this problem. We review the characteristics of clinically used electromagnetic fields and discuss which components of these fields may actually be responsible for altering the activity of the bone cells. We then consider several physical mechanisms which have been proposed to explain how the cells within the bone or fracture tissue detect this field component.

  9. Relativistic particle motion in nonuniform electromagnetic waves

    NASA Technical Reports Server (NTRS)

    Schmidt, G.; Wilcox, T.

    1973-01-01

    A charged particle moving in a strong nonuniform electromagnetic wave which suffers a net acceleration in the direction of the negative intensity gradient of the wave was investigated. Electrons will be expelled perpendicularly from narrow laser beams and various instabilities result.

  10. Complementary Electromagnetic Non-Destructive Evaluation

    NASA Astrophysics Data System (ADS)

    Tian, Gui Yun; Wilson, John; Morozov, Maxim

    2011-06-01

    The use of non-destructive evaluation (NDE) for defect detection and failure prediction in structures and specimens is widespread in energy industries, aimed at ageing power plants and pipelines, material degradation, fatigue and radiation damage, etc. At present there are no suitable electromagnetic NDE methods for the measurement and characterization of material degradation, in irradiated samples in particular, which is very important and timely for the nuclear power industry in the UK. This paper reports recent developments in the field of electromagnetic (EM) NDE at Newcastle University, including pulsed eddy current (PEC), pulsed magnetic flux leakage (PMFL), magnetic Barkhausen emission (MBE) and magneto-acoustic emission (MAE). As different EM methods have different strengths, an integrative EM framework is introduced. Case studies through the second round robin tests organized by the Universal Network for Magnetic Non-Destructive Evaluation (UNMNDE), representing eighteen leading research groups worldwide in the area of electromagnetic NDE, are reported. Twelve samples with different ageing times and rolling reduction ratios were tested using different magnetic methods among the UNMNDE members. Based on the studies, the complementary characteristics of electromagnetic techniques for NDE are discussed.

  11. Relativistic particle motion in nonuniform electromagnetic waves

    NASA Technical Reports Server (NTRS)

    Schmidt, G.; Wilcox, T.

    1973-01-01

    It is shown that a charged particle moving in a strong nonuniform electromagnetic wave suffers a net acceleration in the direction of the negative intensity gradient of the wave. Electrons will be expelled perpendicularly from narrow laser beams and various instabilities can result.

  12. Relations Among Systems of Electromagnetic Equations

    ERIC Educational Resources Information Center

    page, Chester H.

    1970-01-01

    Contends that the equations of electromagnetism, whether in rationalized or non-rationalized form, express an invariant set of physical relationships. The relationships among corresponding symbols are given and applied to precise statements about the relation between the oersted and the amphere per meter, the abampere and the ampere, etc.…

  13. Electromagnetism Adapted for Life Science Students

    ERIC Educational Resources Information Center

    Gurr, F. M.; And Others

    1974-01-01

    Describes the study of electronics as a terminal course in electromagnetism. A lecture-laboratory approach is used with a strong emphasis on practical experience. Outlines the major topics of the lecture program and describes the activities used in the laboratory. (GS)

  14. Charging Ahead: An Introduction to Electromagnetism.

    ERIC Educational Resources Information Center

    Shafer, Larry E.

    This guide explores the connection between electricity and magnetism with middle level and high school students. The phenomenon of electromagnetism is broken down into four lesson plans that provide students and teachers with a carefully constructed yet easy way to learn about their history. All four activities prompt students to use inexpensive,…

  15. Charging Ahead: An Introduction to Electromagnetism.

    ERIC Educational Resources Information Center

    Shafer, Larry E.

    This guide explores the connection between electricity and magnetism with middle level and high school students. The phenomenon of electromagnetism is broken down into four lesson plans that provide students and teachers with a carefully constructed yet easy way to learn about their history. All four activities prompt students to use inexpensive,

  16. Accuracy Assessment for AG500, Electromagnetic Articulograph

    ERIC Educational Resources Information Center

    Yunusova, Yana; Green, Jordan R.; Mefferd, Antje

    2009-01-01

    Purpose: The goal of this article was to evaluate the accuracy and reliability of the AG500 (Carstens Medizinelectronik, Lenglern, Germany), an electromagnetic device developed recently to register articulatory movements in three dimensions. This technology seems to have unprecedented capabilities to provide rich information about time-varying

  17. Resonant response of electromagnetic scattering from ellipsoid

    NASA Astrophysics Data System (ADS)

    Gavriloaia, Mihai-Bogdan; Vizireanu, Constantin-Radu; Neamtu, Catalin; Preda, Radu; Achimescu, Emanuel; Halunga, Simona

    2015-02-01

    Modern radars must provide in a very short time: existence, mobility and shape of objects evolving in airspace. Evaluation of the object shapes through active research by using synthetic aperture radar is limited in time, resolution, and cost. A new way of processing non-stationary signals is presented in this article. Signals are obtained from the reflection of the electromagnetic field by objects with complex shape when they are irradiated with linear frequency modulated signals. The amplitude of reflected signal is variable on the radio-impulse duration depending on object shape, causing a certain electromagnetic signature. This phenomenon is caused by specific electromagnetic resonance. The reflected signal has maximum amplitude when the frequency of the incident wave is the same with the resonant frequency of the investigated object. The structure of an radar target can be decomposed into simple geometric shapes such as spheres, ellipsoids, prisms, and so on. Using resonant effect that ensures pattern recognition is exemplified by an object with an aerodynamic profile accepted in many component elements of the aircraft, namely - an ellipsoid. It is a geometric shape used extensively in aviation, because it has a very low aerodynamic resistance. The resonant response of ellipsoid is evaluated in a decade frequency band, but the pattern recognition of this shape is enough for an octave band. The resonant response is assessed for cross polarization of incident electromagnetic field, as well. As a result, the radio-impulse shape can be used in a data base for pattern recognition.

  18. 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.

  19. Electromagnetic interference analysis of magnetic resistance sensors inside a projectile under complex electromagnetic environments

    NASA Astrophysics Data System (ADS)

    Guo, Qingwei; Gao, Min; Lu, Zhicai; Yang, Peijie

    2013-03-01

    Accurate measurement of angular motion has long been recognized as a daunting task. In recent years the measurement of projectiles utilizing magnetic resistance sensors has become a hot research field. Electromagnetic interference on attitude measurement cannot be ignored in complex electromagnetic environments such as battlefield conditions. In this paper, the influence and function pattern of electromagnetic interference on the measuring performance are theoretically analyzed, and the shielding effectiveness (SE) simulation of projectile is conducted via software Computer Simulation Technology (CST). Considering the specific tests, the intensity of the influence is judged. The simulation indicates that the battlefield's complex electromagnetic environment influences the environment inside the projectile, especially its electronic components and capability. The research results can provide important theoretical support on the errors compensation and precision improvement of the projectile attitude measurement with Magnetic Resistance sensor.

  20. Questions of energy transformation in dc electromagnetic mechanisms. [Electromagnetic energy to energy of mechanical vibrations

    SciTech Connect

    Simonov, B.F.

    1986-05-01

    Electromagnetic reciprocal-motion transducers (EMT) are being used ever more extensively in modern industry. In particular, rubble to break down bulkiness, slicer drives for coal combines, drilling equipment, etc. are produced on the basis of EMT. This paper is devoted to further refinement of energy conversion questions and their analysis. The energy coming from the supply source in the magnetization of the additionally sucked-in armature volume is determined by the magnetic energy density in the armature section at the pole level. A general expression is deduced for the electromagnetic force of the EMT that sets up the interrelation between the whole system magnetic energy and the coil flux-linkage. It is shown that expressions known earlier for the electromagnetic forces, obtained for the constant current electromagnet and the constant flux-linkage cases, are particular cases of the general expression that is valid without any additional constraints for the condition of the EMT working process.

  1. Analysis of waveguides containing EMCs (electromagnetic conductors) or PEMCs (perfect electromagnetic conductors)

    NASA Astrophysics Data System (ADS)

    Prudêncio, Filipa R.; Matos, Sérgio A.; Paiva, Carlos R.

    2014-11-01

    The concept of a perfect electromagnetic conductor (PEMC) was introduced to generalize and unify two well-known and apparently disjoint concepts in electromagnetics: the perfect electric conductor (PEC) and the perfect magnetic conductor (PMC). Although the PEMC has proven a fertile tool in electromagnetic analyses dealing with new and complex boundaries, its corresponding definition as a medium has, nevertheless, raised several problems. In fact, according to its initial 3D definition, the PEMC cannot be considered a unique and well-defined medium: it leads to extraneous fields without physical meaning. By using a previously published generalization of a PEMC that regards this concept both as a boundary and as a medium - which was dubbed an MIM (Minkowskian isotropic medium) and acts, in practice, as an actual electromagnetic conductor (EMC) - it is herein presented a straightforward analysis of waveguides containing PEMCs that readily and systematically follows from the general framework of waveguides containing EMCs.

  2. The continuing challenge of electromagnetic launch

    SciTech Connect

    Cowan, M.; Cnare, E.C.; Duggin, B.W.; Kaye, R.J.; Marder, B.M.; Shokair, I.R.

    1993-07-01

    Interest in launching payloads through the atmosphere to ever higher velocity is robust. For hundreds of years, guns and rockets have been improved for this purpose until they are now considered to be near to their performance limits. While the potential of electromagnetic technology to increase launch velocity has been known since late in the nineteenth century, it was not until about 1980 that a sustained and large-scale effort was started to exploit it. Electromagnetic launcher technology is restricted here to mean only that technology which establishes both a current density, J, and a magnetic field, B, within a part of the launch package, called the armature, so that J {times} B integrated over the volume of the armature is the launching force. Research and development activity was triggered by the discovery that high velocity can be produced with a simple railgun which uses an arc for its armature. This so called ``plasma-armature railgun`` has been the launcher technology upon which nearly all of the work has focused. Still, a relatively small parallel effort has also been made to explore the potential of electromagnetic launchers which do not use sliding contacts on stationary rails to establish current in the armature. One electromagnetic launcher of this type is called an induction coilgun because armature current is established by electromagnetic induction. In this paper, we first establish terminology which we will use not only to specify requirements for successful endoatmospheric launch but also to compare different launcher types. Then, we summarize the statuses of the railgun and induction coilgun technologies and discuss the issues which must be resolved before either of these launchers can offer substantial advantage for endoatomospheric launch.

  3. Determining and controlling the electromagnetic environment for Space Station Freedom

    NASA Astrophysics Data System (ADS)

    Pearson, S. D.; McCollum, M. B.

    1993-01-01

    Critical issues facing the SSF electromagnetic compatibility community are discussed focusing on effective utilization of SSF resources to perform overall SSF verification. Attention is also given to management and phases of an Electromagnetic Environment Effects Control Program (EEECP) aimed at producing an electromagnetically compatible station.

  4. Electromagnetic interaction in the theory of straight strings

    SciTech Connect

    Nikitin, I.N.; Pron`ko, G.P.

    1995-06-01

    A scheme is proposed for including electromagnetic interaction into the theories of stretched relativistic objects. In the theory of the straight string, the operator of electromagnetic interaction is constructed, and form factors of electromagnetic transitions are calculated. 6 refs., 1 fig.

  5. Experimental progress and status on nucleon electromagnetic form factors

    NASA Astrophysics Data System (ADS)

    Gao, H.; Peng, C.; Zhao, Z. W.

    2016-03-01

    Nucleon electromagnetic form factors are the fundamental quantities that are related to a two-dimensional view of the charge and magnetization distribution in the nucleon. They are essential in understanding the nucleon electromagnetic structure. In this article, we briefly summarize the recent experimental progress on this topic, and introduce several experiments related to the nucleon electromagnetic form factors in the near future.

  6. Pre-Metric Electromagnetism as a Path to Unification

    NASA Astrophysics Data System (ADS)

    Delphenich, David

    It is shown that the pre-metric approach to Maxwell's equations provides an alternative to the traditional Einstein- Maxwell unification problem, namely, that electromagnetism and gravitation are unified in a different way that makes the gravitational field a consequence of the electromagnetic constitutive properties of spacetime, by way of the dispersion law for the propagation of electromagnetic waves.

  7. Electronic systems failures and anomalies attributed to electromagnetic interference

    NASA Technical Reports Server (NTRS)

    Leach, R. D. (Editor); Alexander, M. B. (Editor)

    1995-01-01

    The effects of electromagnetic interference can be very detrimental to electronic systems utilized in space missions. Assuring that subsystems and systems are electrically compatible is an important engineering function necessary to assure mission success. This reference publication will acquaint the reader with spacecraft electronic systems failures and anomalies caused by electromagnetic interference and will show the importance of electromagnetic compatibility activities in conjunction with space flight programs. It is also hoped that the report will illustrate that evolving electronic systems are increasingly sensitive to electromagnetic interference and that NASA personnel must continue to diligently pursue electromagnetic compatibility on space flight systems.

  8. A strong permanent magnet-assisted electromagnetic undulator

    DOEpatents

    Halbach, K.

    1987-01-30

    This invention discloses an improved undulator comprising a plurality of electromagnet poles located along opposite sides of a particle beam axis with alternate north and south poles on each side of the beam to cause the beam to wiggle or undulate as it travels generally along the beam axis and permanent magnets spaced adjacent the electromagnetic poles on each side of the axis of said particle beam in an orientation sufficient to reduce the saturation of the electromagnet poles whereby the field strength of the electromagnet poles can be increased beyond the normal saturation levels of the electromagnetic poles. 4 figs.

  9. Applications of the electromagnetic Helmholtz resonator*

    NASA Astrophysics Data System (ADS)

    Stoneback, Russell Alan

    An electromagnetic Helmholtz resonator comprised of a capacitor with an aperture is investigated theoretically and experimentally. It is proposed that this resonance may be described using effective impedances describing the capacitor and aperture, similar to lumped element descriptions of the acoustic Helmholtz resonator. The dipole impedance of an electromagnetic aperture is derived and verified using the finite element method. Incorporating standard network relations, the aperture impedance can be used to calculate radiated power. Measurements of a capacitor demonstrates that the transmitted voltage through the capacitor is modified by induced charges. An induced voltage is introduced, and predictions agree with observations. Measurements of a capacitor with an aperture in the grounded plate indicate that induced currents cancel the imaginary impedance of the aperture, and double the real impedance. The observed impedance is close to predictions using the derived aperture impedance, confirming the utility of the aperture impedance in describing the system. The numerically obtained aperture electromagnetic fields are similar to the Birkeland current distribution and the cross polar cap potential in the Earth's polar ionosphere, motivating a model where the polar ionosphere is treated as an effective aperture. It is proposed that this effective aperture interacts with the capacitor formed between the Earth and ionosphere, creating an electromagnetic Helmholtz resonator. Predictions made with this model agree with measurements of transmitted power and phase velocity by FAST during a geomagnetic substorm, measurements of the Ionospheric Alfven Resonator, and oscillations recorded by ground based magnetometers. The same effective aperture behavior is expected in sunspots and polar coronal holes. A peak is predicted in Alfven wave power across the transition region for waves with a 5 min. period that delivers an average power over 100 W/m2 to the corona, sufficient to heat the quiet corona and launch the solar wind. Applied to sunspots, a minimum umbral temperature of 3750 K is predicted with a peak in transmitted power at 3 min., consistent with observations. A prototype electromagnetic guitar and associated methods to obtain music are also presented. These instruments replace the acoustic systems normally employed for musical instruments with electromagnetic equivalents and music samples are presented. *U.S. PATENTS PENDING 20070017344, 20070017345, 20070214940

  10. A new adaptive hybrid electromagnetic damper: modelling, optimization, and experiment

    NASA Astrophysics Data System (ADS)

    Asadi, Ehsan; Ribeiro, Roberto; Behrad Khamesee, Mir; Khajepour, Amir

    2015-07-01

    This paper presents the development of a new electromagnetic hybrid damper which provides regenerative adaptive damping force for various applications. Recently, the introduction of electromagnetic technologies to the damping systems has provided researchers with new opportunities for the realization of adaptive semi-active damping systems with the added benefit of energy recovery. In this research, a hybrid electromagnetic damper is proposed. The hybrid damper is configured to operate with viscous and electromagnetic subsystems. The viscous medium provides a bias and fail-safe damping force while the electromagnetic component adds adaptability and the capacity for regeneration to the hybrid design. The electromagnetic component is modeled and analyzed using analytical (lumped equivalent magnetic circuit) and electromagnetic finite element method (FEM) (COMSOL® software package) approaches. By implementing both modeling approaches, an optimization for the geometric aspects of the electromagnetic subsystem is obtained. Based on the proposed electromagnetic hybrid damping concept and the preliminary optimization solution, a prototype is designed and fabricated. A good agreement is observed between the experimental and FEM results for the magnetic field distribution and electromagnetic damping forces. These results validate the accuracy of the modeling approach and the preliminary optimization solution. An analytical model is also presented for viscous damping force, and is compared with experimental results The results show that the damper is able to produce damping coefficients of 1300 and 0-238 N s m-1 through the viscous and electromagnetic components, respectively.

  11. Does electromagnetic radiation accelerate galactic cosmic rays

    NASA Technical Reports Server (NTRS)

    Eichler, D.

    1977-01-01

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

  12. Subsurface discrimination using electromagnetic induction sensors

    NASA Astrophysics Data System (ADS)

    Bell, Thomas H.; Barrow, Bruce J.; Miller, Jonathan M.

    2000-07-01

    This paper reviews the problem of subsurface discrimination using electromagnetic induction sensors. Typically, discrimination is based on differences in the multiaxis magnetic polarizability between different objects. We review work on frequency and time domain systems, and their interrelationship. We present the results of comprehensive measurements of the multiaxis electromagnetic induction response of a variety of inert ordnance items, ordnance fragments and scrap metal pieces recovered from firing ranges. The extent to which the distributions of the eigenvalues of magnetic polarizability for the different classes of objects do not overlap establishes an upper bound on discrimination. For various reasons, the eigenvalues cannot always be accurately determined using data collected above a buried target. This tends to increase the overlap of the distributions, and hence degrade discrimination performance.

  13. Electromagnetic PIC modeling with a background gas

    SciTech Connect

    Verboncoeur, J.P.; Cooperberg, D.

    1997-02-01

    Modeling the interaction of relativistic electromagnetic plasmas with a background gas is described. The timescales range over many orders of magnitude, from the electromagnetic Courant condition ({approximately}10{sup {minus}12}sec) to electron-neutral collision times ({approximately}10{sup {minus}7}sec) to ion transit times ({approximately}10{sup {minus}5}sec). For this work, the traditional Monte Carlo algorithm [1] is described for relativistic electrons. Subcycling is employed to improve efficiency, and smoothing is employed to reduce particle noise. Applications include plasma-focused electron guns, gas-filled microwave tubes, surface wave discharges driven at microwave frequencies, and electron-cyclotron resonance discharges. The method is implemented in the OOPIC code [2]. {copyright} {ital 1997 American Institute of Physics.}

  14. Dielectric sensors based on electromagnetic energy tunneling.

    PubMed

    Siddiqui, Omar; Kashanianfard, Mani; Ramahi, Omar

    2015-01-01

    We show that metallic wires embedded in narrow waveguide bends and channels demonstrate resonance behavior at specific frequencies. The electromagnetic energy at these resonances tunnels through the narrow waveguide channels with almost no propagation losses. Under the tunneling behavior, high-intensity electromagnetic fields are produced in the vicinity of the metallic wires. These intense field resonances can be exploited to build highly sensitive dielectric sensors. The sensor operation is explained with the help of full-wave simulations. A practical setup consisting of a 3D waveguide bend is presented to experimentally observe the tunneling phenomenon. The tunneling frequency is predicted by determining the input impedance minima through a variational formula based on the Green function of a probe-excited parallel plate waveguide. PMID:25835188

  15. Electromagnetically induced transparency in an entangled medium.

    PubMed

    Li, Weibin; Viscor, Daniel; Hofferberth, Sebastian; Lesanovsky, Igor

    2014-06-20

    We theoretically investigate light propagation and electromagnetically induced transparency in a quasi-one-dimensional gas in which atoms interact strongly via exchange interactions. We focus on the case in which the gas is initially prepared in a many-body state that contains a single excitation and conduct a detailed study of the absorptive and dispersive properties of such a medium. This scenario is achieved in interacting gases of Rydberg atoms with two relevant S states that are coupled through exchange. Of particular interest is the case in which the medium is prepared in an entangled spin-wave state. This, in conjunction with the exchange interaction, gives rise to a nonlocal susceptibility that--in comparison to conventional Rydberg electromagnetically induced transparency--qualitatively alters the absorption and propagation of weak probe light, leading to nonlocal propagation and enhanced absorption. PMID:24996088

  16. Radiated fields from an electromagnetic pulse simulator

    NASA Astrophysics Data System (ADS)

    Pelletier, M.; Delisle, G. Y.; Kashyap, S.

    Simulators of electromagnetic pulses allow generation within a limited time of very high-intensity fields such as those produced in a nuclear explosion. These fields can be radiated out of the test zone at a lower but nevertheless significant level; if the intensity of these fields is sufficiently high, damage to humans and electronic equipment can result. An evaluation of the potential danger of these simulator emissions requires knowledge of the amplitude, duration, and the energy of the radiated impulses. A technique is presented for calculating the fields radiated by a parallel-plane electromagnetic pulse simulator. The same method can also be applied to a rhombic type simulator. Sample numerical results are presented along with the calculations of the energy and power density and a discussion of the formation of the field in the frequency domain.

  17. Electromagnetic scattering by pyramidal and wedge absorber

    NASA Technical Reports Server (NTRS)

    Dewitt, Brian T.; Burnside, Walter D.

    1988-01-01

    Electromagnetic scattering from pyramidal and wedge absorbers used to line the walls of modern anechoic chambers is measured and compared with theoretically predicted values. The theoretical performance for various angles of incidence is studied. It is shown that a pyramidal absorber scatters electromagnetic energy more as a random rough surface does. The apparent reflection coefficient from an absorber wall illuminated by a plane wave can be much less than the normal absorber specifications quoted by the manufacturer. For angles near grazing incidence, pyramidal absorbers give a large backscattered field from the pyramid side-faces or edges. The wedge absorber was found to give small backscattered fields for near-grazing incidence. Based on this study, some new guidelines for the design of anechoic chambers are advocated because the specular scattering models used at present do not appear valid for pyramids that are large compared to the wavelength.

  18. Pulsed thrust measurements using electromagnetic calibration techniques

    SciTech Connect

    Tang Haibin; Shi Chenbo; Zhang Xin'ai; Zhang Zun; Cheng Jiao

    2011-03-15

    A thrust stand for accurately measuring impulse bits, which ranged from 10-1000 {mu}N s using a noncontact electromagnetic calibration technique is described. In particular, a permanent magnet structure was designed to produce a uniform magnetic field, and a multiturn coil was made to produce a calibration force less than 10 mN. The electromagnetic calibration force for pulsed thrust measurements was linear to the coil current and changed less than 2.5% when the distance between the coil and magnet changed 6 mm. A pulsed plasma thruster was first tested on the thrust stand, and afterward five single impulse bits were measured to give a 310 {mu}N s average impulse bit. Uncertainty of the measured impulse bit was analyzed to evaluate the quality of the measurement and was found to be 10 {mu}N s with 95% credibility.

  19. Electromagnetic model for propagation through clouds

    NASA Astrophysics Data System (ADS)

    Seker, S. S.

    Electromagnetic propagation through a sparse distribution of lossy dielectric particles in a cloud is investigated. A mathematical model is developed to aid in the interpretation of the interaction data obtained by electromagnetic remote probing of mixed ice crystal and waterdrop clouds. Such clouds can contain many possible crystal forms, most notably thin long cylinder, bullets, and flat plate crystals. Bistatic reflectivity and attenuation are computed for waves of selected polarizations passing through clouds with specified size, shape, and distributions. The proposed formulation is matrix and stochastic in nature, and easily accomodates arbitrary polarization states. It allows complete characterization of medium depolarization effects from hydrometers (e.g., attenuation, isolation, and shape shift). The results obtained are of interest in connection with the study of the effects of clouds on microwave or millimeter-wave communications.

  20. Electromagnetic detection of a perfect carpet cloak.

    PubMed

    Shi, Xihang; Gao, Fei; Lin, Xiao; Zhang, Baile

    2015-01-01

    It has been shown that a spherical invisibility cloak originally proposed by Pendry et al. can be electromagnetically detected by shooting a charged particle through it, whose underlying mechanism stems from the asymmetry of transformation optics applied to motions of photons and charges [PRL 103, 243901 (2009)]. However, the conceptual three-dimensional invisibility cloak that exactly follows specifications of transformation optics is formidably difficult to implement, while the simplified cylindrical cloak that has been experimentally realized is inherently visible. On the other hand, the recent carpet cloak model has acquired remarkable experimental development, including a recently demonstrated full-parameter carpet cloak without any approximation in the required constitutive parameters. In this paper, we numerically investigate the electromagnetic radiation from a charged particle passing through a perfect carpet cloak and propose an experimentally verifiable model to demonstrate symmetry breaking of transformation optics. PMID:25997798

  1. Electromagnetic Detection of a Perfect Carpet Cloak

    NASA Astrophysics Data System (ADS)

    Shi, Xihang; Gao, Fei; Lin, Xiao; Zhang, Baile

    2015-05-01

    It has been shown that a spherical invisibility cloak originally proposed by Pendry et al. can be electromagnetically detected by shooting a charged particle through it, whose underlying mechanism stems from the asymmetry of transformation optics applied to motions of photons and charges [PRL 103, 243901 (2009)]. However, the conceptual three-dimensional invisibility cloak that exactly follows specifications of transformation optics is formidably difficult to implement, while the simplified cylindrical cloak that has been experimentally realized is inherently visible. On the other hand, the recent carpet cloak model has acquired remarkable experimental development, including a recently demonstrated full-parameter carpet cloak without any approximation in the required constitutive parameters. In this paper, we numerically investigate the electromagnetic radiation from a charged particle passing through a perfect carpet cloak and propose an experimentally verifiable model to demonstrate symmetry breaking of transformation optics.

  2. Classical electromagnetic radiation of the Dirac electron

    NASA Technical Reports Server (NTRS)

    Lanyi, G.

    1973-01-01

    A wave-function-dependent four-vector potential is added to the Dirac equation in order to achieve conservation of energy and momentum for a Dirac electron and its emitted electromagnetic field. The resultant equation contains solutions which describe transitions between different energy states of the electron. As a consequence it is possible to follow the space-time evolution of such a process. This evolution is shown in the case of the spontaneous emission of an electromagnetic field by an electron bound in a hydrogen-like atom. The intensity of the radiation and the spectral distribution are calculated for transitions between two eigenstates. The theory gives a self-consistent deterministic description of some simple radiation processes without using quantum electrodynamics or the correspondence principle.

  3. Electromagnetic Moments of Exotic Nuclei: Recent Studies

    SciTech Connect

    Balabanski, Dimiter L.

    2007-04-23

    State-of-the-art studies of electromagnetic moments of exotic nuclei in experiments with radioactive beams are presented. These include first results on the 19/2+ isomer in 127Sn, which was populated in a relativistic fragmentation reaction within the g-RISING campaign at GSI, Darmstadt, Germany, and the first measurement of a nuclear quadrupole moment of an isomeric state in fragmentation reaction, that of the 9/2+ isomer in 61Fe, which was performed at GANIL, Caen, France. Results from experiments to measure the electromagnetic moments in transfer reactions are also discussed, as well as the perspectives to utilize this technique in experiments with post-accelerated ISOL beams in inverse kinematics.

  4. SP-100 Thermoelectric Electromagnetic Pump Performance Model

    NASA Astrophysics Data System (ADS)

    Salamah, Samir A.,; Miller, David D.; Sinha, Upendra

    1994-07-01

    The thermoelectric electromagnetic (TEM) pump is a key component of the SP-100 space nuclear power system that reliably pumps liquid metals through both the primary heat transport and the secondary or heat rejection subsystems. The TEM Pump Performance (TiPP) Model is a performance prediction and design tool, developed from first principles, that determines developed and delivered pressures for different geometries and conditions of the TEM pump. Several key analytical models used in the performance prediction of the TEM pump have been experimentally demonstrated in the Magnetic Bench Test (MBT) and the Electro-Magnetic Integration Test (EMIT). These tests focused on specific phenomena of the pump. The model predictions are based on given inlet temperatures of the fluids and their flow rates. Detailed 3-dimensional modelling, including end effects, is performed by the modules in the code. Different fluids can be readily simulated. A sample application is included and results compared with a single-point model predictions.

  5. 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

  6. The Linear Bicharacteristic Scheme for Electromagnetics

    NASA Technical Reports Server (NTRS)

    Beggs, John H.

    2001-01-01

    The upwind leapfrog or Linear Bicharacteristic Scheme (LBS) has previously been implemented and demonstrated on electromagnetic wave propagation problems. This paper extends the Linear Bicharacteristic Scheme for computational electromagnetics to model lossy dielectric and magnetic materials and perfect electrical conductors. This is accomplished by proper implementation of the LBS for homogeneous lossy dielectric and magnetic media and for perfect electrical conductors. Heterogeneous media are modeled through implementation of surface boundary conditions and no special extrapolations or interpolations at dielectric material boundaries are required. Results are presented for one-dimensional model problems on both uniform and nonuniform grids, and the FDTD algorithm is chosen as a convenient reference algorithm for comparison. The results demonstrate that the explicit LBS is a dissipation-free, second-order accurate algorithm which uses a smaller stencil than the FDTD algorithm, yet it has approximately one-third the phase velocity error. The LBS is also more accurate on nonuniform grids.

  7. Electromagnetic inverse applications for functional brain imaging

    SciTech Connect

    Wood, C.C.

    1997-10-01

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). This project addresses an important mathematical and computational problem in functional brain imaging, namely the electromagnetic {open_quotes}inverse problem.{close_quotes} Electromagnetic brain imaging techniques, magnetoencephalography (MEG) and electroencephalography (EEG), are based on measurements of electrical potentials and magnetic fields at hundreds of locations outside the human head. The inverse problem is the estimation of the locations, magnitudes, and time-sources of electrical currents in the brain from surface measurements. This project extends recent progress on the inverse problem by combining the use of anatomical constraints derived from magnetic resonance imaging (MRI) with Bayesian and other novel algorithmic approaches. The results suggest that we can achieve significant improvements in the accuracy and robustness of inverse solutions by these two approaches.

  8. 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.

  9. Electromagnetic spectum: a critical natural resource

    SciTech Connect

    Herter, C.A. Jr.

    1985-07-01

    Little has been written about the electromagnetic spectrum, which is the natural resource which makes modern communication and communications development possible. Even though its physical dimensions are infinite, and it can never be depleted, the constantly increased demands for use of the spectrum constrain the extent to which it can be exploited without unacceptable interference. Over-use and over-crowding cause interference and impair the use of the radio spectrum. No other natural resource has such as immediate and extensive impact on modern civilization. The author explores the nature of the electromagnetic spectrum as a natural and common property resource; elaborates on some of its uses, particularly in conjunction with the geostationary orbit; examines the institutional frameworks that have been developed to manage the resource; and discusses some of the emerging political and legal problems it entails.

  10. Shaping metallic glasses by electromagnetic pulsing.

    PubMed

    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

  11. Polarization Beating of Random Electromagnetic Beams

    NASA Astrophysics Data System (ADS)

    Lajunen, H.; Salaj, J.; Setälä, T.

    2016-02-01

    We consider temporal interference of two stationary, quasi-monochromatic, partially polarized optical beams with different mean frequencies. We show that both the intensity and the polarization state, represented by the Stokes parameters, exhibit beating, i.e., periodic temporal variation with frequency specified by the difference of the mean frequencies. The contrasts, or visibilities, of the Stokes-parameter changes are characterized by the equal-time electromagnetic degree of coherence between the beams. If the beams are otherwise identical random processes, but with spectra centered at different frequencies, then the polarization modulation is characterized by the degree of polarization, consistently with a recent interferometric interpretation of this quantity. Our results provide insight into the role of polarization in beating of electromagnetic waves.

  12. Radiofrequency Electromagnetic Field Map of Timisoara

    NASA Astrophysics Data System (ADS)

    Stefu, N.; Solyom, I.; Arama, A.

    2015-12-01

    There are many electromagnetic field (EMF) sources nowadays acting simultaneously, especially in urban areas, making the theoretical estimation of electromagnetic power at ground level very difficult. This paper reports on EMF maps built with measurements collected in Timisoara, at various radiofrequencies. A grid of 15×15 squares was built (approximate resolution 400m x 400m) and measurements of the average and maximum values of the electric field E, magnetic field H and total power density S at 0.9, 1.8 and 2.4 GHz were collected in every node of the grid. Positions of the nodes in terms of latitude and longitude were also collected. Maps were built presenting the spatial distribution of the measured quantities over Timisoara. Potential influences of EMF on public health are discussed.

  13. Electromagnetic radiation absorbers and modulators comprising polyaniline

    DOEpatents

    Epstein, Arthur J.; Ginder, John M.; Roe, Mitchell G.; Hajiseyedjavadi, Hamid

    1992-01-01

    A composition for absorbing electromagnetic radiation, wherein said electromagnetic radiation possesses a wavelength generally in the range of from about 1000 Angstroms to about 50 meters, wherein said composition comprises a polyaniline composition of the formula ##STR1## where y can be equal to or greater than zero, and R.sup.1 and R.sup.2 are independently selected from the group containing of H, --OCH.sub.3, --CH.sub.3, --F, --Cl, --Br, --I, NR.sup.3 .sub.2, --NHCOR.sup.3, --OH, --O.sup.-, SR.sup.3, --OCOR.sup.3, --NO.sub.2, --COOH, --COOR.sup.3, --COR.sup.3, --CHO, and --CN, where R.sup.3 is a C.sub.1 to C.sub.8 alkyl, aryl or aralkyl group.

  14. Electromagnetically-driven capillary switches and oscillators

    NASA Astrophysics Data System (ADS)

    Malouin, Bernard; Hirsa, Amir; Vogel, Michael

    2009-11-01

    By designing pinned-contact, coupled droplet pairs at the appropriate length scale to promote surface tension as the dominant force, one can create bi-stable capillary switches and natural oscillators. These systems have been triggered by pressure pulses, electrochemistry, and electroosmosis. These methods are typically accompanied by bulky setups or slow response times. An alternate approach exploits electromagnetic activation. Our device consists of a millimeter scale orifice, overfilled with an aqueous ferrofluid, in proximity to a wire coil that generates a magnetic field. Experimental evidence of such capillary switches and energy efficient oscillators is presented here. Comparisons to a simplified model are also presented. This activation method is shown to have relatively fast response times, low driving voltages, and individual addressability. Electromagnetically activated capillary switches and oscillators offer many applications ranging from high-speed adaptive optics to micro-actuators, with possible circuit board integration.

  15. Nonionizing electromagnetic fields and cancer: a review.

    PubMed

    Salvatore, J R; Weitberg, A B; Mehta, S

    1996-04-01

    Low-frequency electromagnetic radiation had previously been thought to cause human injury only by generation of excess heat or by shock from direct contact with electric current. Information accumulating over the past few decades, however, suggests that nonionizing electric and magnetic fields associated with this radiation may be an environmental etiology in human disease. Human beings are affected not only by natural background nonionizing electromagnetic fields produced by the Earth, but also by a host of manmade sources. Of the diseases believed related to these fields, cancer and participation of these fields in the carcinogenic process have received considerable attention. This paper is a review of the basic science that points to this possible association. PMID:8723289

  16. Electromagnetic Detection of a Perfect Carpet Cloak

    PubMed Central

    Shi, Xihang; Gao, Fei; Lin, Xiao; Zhang, Baile

    2015-01-01

    It has been shown that a spherical invisibility cloak originally proposed by Pendry et al. can be electromagnetically detected by shooting a charged particle through it, whose underlying mechanism stems from the asymmetry of transformation optics applied to motions of photons and charges [PRL 103, 243901 (2009)]. However, the conceptual three-dimensional invisibility cloak that exactly follows specifications of transformation optics is formidably difficult to implement, while the simplified cylindrical cloak that has been experimentally realized is inherently visible. On the other hand, the recent carpet cloak model has acquired remarkable experimental development, including a recently demonstrated full-parameter carpet cloak without any approximation in the required constitutive parameters. In this paper, we numerically investigate the electromagnetic radiation from a charged particle passing through a perfect carpet cloak and propose an experimentally verifiable model to demonstrate symmetry breaking of transformation optics. PMID:25997798

  17. Shaping metallic glasses by electromagnetic pulsing

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  18. Development of a laced electromagnetic wiggler

    SciTech Connect

    Christensen, T.C.; Burns, M.J.; Deis, G.A.; Parkison, C.D.; Halbach, K.

    1988-03-01

    The laced electromagnetic wiggler is a new concept being developed to attain higher magnetic fields, shorter wavelengths, and larger gaps for the induction-linear accelerator, free-electron-laser (FEL) program. In the laced wiggler design, permanent magnets are located (''laced'') between the electromagnetic coils to increase the reverse-bias flux in the iron pole beyond that possible with only pole-edge (''side'') permanent magnets. This increase in reverse-bias flux allows wiggler operation at midplane magnetic field intensities comparable to those of a hybrid permanent magnet/steel wiggler, but with field adjustability over a specified range. The maximum field intensity and tuning range are selected, within limits, for specific design requirements. The authors have designed and tested a one-period prototype of this concept with promising results.

  19. Development of a laced electromagnetic wiggler

    SciTech Connect

    Christensen, T.C.; Burns, M.J.; Deis, G.A.; Parkison, C.D.; Prosnitz, D.; Halbach, K.

    1987-01-01

    The laced electromagnetic wiggler is a new concept being developed to attain higher magnetic fields, shorter wavelengths, and larger gaps for the induction-linear accelerator, free-electron-laser (FEL) program. In the laced wiggler design, permanent magnets are located (''laced'') between the electromagnetic coils to increase the reverse-bias flux in the iron pole beyond that possible with only pole-edge (''side'') permanent magnets. This increase in reverse-bias flux allows wiggler operation at midplane magnetic field intensities comparable to those of a hybrid permanent magnet/steel wiggler, but with field adjustability over a specified range. The maximum field intensity and tuning range are selected, within limits, for specific design requirements. We have designed and tested a one-period prototype of this concept with promising results.

  20. Computational modeling of nonlinear electromagnetic phenomena

    NASA Technical Reports Server (NTRS)

    Goorjian, Peter M.; Taflove, Allen

    1992-01-01

    A new algorithm has been developed that permits, for the first time, the direct time integration of the full-vector nonlinear Maxwell's equations. This new capability permits the modeling of linear and nonlinear, instantaneous and dispersive effects in the electric polarization material media. Results are presented of first-time calculations in 1D of the propagation and collision of femtosecond electromagnetic solitons that retain the optical carrier.

  1. Pullback transformation in gyrokinetic electromagnetic simulations

    SciTech Connect

    Mishchenko, Alexey Könies, Axel; Kleiber, Ralf; Cole, Michael

    2014-09-15

    It is shown that a considerable mitigation of the cancellation problem can be achieved by a slight modification of the simulation scheme. The new scheme is verified, simulating a Toroidal Alfvén Eigenmode in tokamak geometry at low perpendicular mode numbers, the so-called “MHD limit.” Also, an electromagnetic drift mode has been successfully simulated in a stellarator.

  2. Electromagnetic pulse and the electric power network

    SciTech Connect

    Klein, K.W.; Barnes, P.R.; Zaininger, H.W.

    1984-01-01

    This paper defines the nuclear electromagnetic pulse (EMP) - electric power system interaction problem. A description of high altitude EMP (HEMP) characteristics, source region EMP (SREMP) characteristics, and magnetohydrodynamics EMP (MHD-EMP) characteristics are presented. The results of initial calculations of EMP induced surges on electric power transmission and distribution lines are presented and compared with lightning induced surges. Potential EMP impacts on electric power systems are discussed, and an overview of the Department of Energy (DOE) EMP research program is presented.

  3. Some Practical Aspects of Electromagnetic Activation

    NASA Astrophysics Data System (ADS)

    MacLeod, C.; Gow, K. S.; Capanni, N.

    Electromagnetic Activation (EMA) is an alternative to combustion in Scramjet-like hypersonic engines. The basis of the system was outlined in previous publications. This paper builds on these results and explores some further practical and theoretical aspects of its operation. These include the beam paths and thermodynamics of the duct, the efficiency of the system, a review of the available radiation generation devices and a discussion of power supply options.

  4. Science 101: What Causes Electromagnetic Induction?

    ERIC Educational Resources Information Center

    Robertson, Bill

    2013-01-01

    Electromagnetic induction is the technical name for the fact that, when a wire is moved near a magnet or a magnet is moved near a wire, an electric current flows in the wire. Although Bill Robertson honestly admits to not knowing why this happens, he does say that it is possible to get a deeper understanding of what's going on in terms of

  5. Monitoring Polymer Curing Via Electromagnetic Impedance

    NASA Technical Reports Server (NTRS)

    Freeman, William T.; Covington, John C.; Kranbuehl, David E.; Hoff, Melanie; Delos, Susan

    1992-01-01

    New nondestructive in-situ electromagnetic-impedance measurement technique senses cure-processing properties of high-temperature, high-performance thermostat and thermoplastic resins. Continuous frequency-dependent measurement and analysis performed during curing cycle. Monitors and measures molecular properties of polymeric resin in liquid and solid states. Applications include nondestructive means for evaluation of materials, determination of "window" boundaries of curing cycles of thermoplastics and thermoset resins, and for online, closed-loop control of curing cycles.

  6. Vector resonances and electromagnetic nucleon structure

    SciTech Connect

    Williams, R.A.; Krewald, S.; Linen, K. )

    1995-02-01

    Motivated by new, precise magnetic proton form factor data in the timelike reigon, a hybrid vector meson dominance (hVMD) formalism is employed to investigate the significance of excited vector meson rsonances on electromagnetic nucleon structure. We find that the [rho](1700), [omega](1600), and two previously unobserved states are required to reproduce the local structure seen in the new LEAR data just above the [ital p[bar p

  7. Science 101: What Causes Electromagnetic Induction?

    ERIC Educational Resources Information Center

    Robertson, Bill

    2013-01-01

    Electromagnetic induction is the technical name for the fact that, when a wire is moved near a magnet or a magnet is moved near a wire, an electric current flows in the wire. Although Bill Robertson honestly admits to not knowing why this happens, he does say that it is possible to get a deeper understanding of what's going on in terms of…

  8. Velocity damper for electromagnetically levitated materials

    SciTech Connect

    Fox, R.J.

    1992-12-31

    A system for damping oscillatory and spinning motions induced in an electromagnetically levitated material. Two opposed field magnets are located orthogonally to the existing levitation coils for providing a DC quadrupole field (cusp field) around the material. The material used for generating the DC quadrupole field must be nonconducting to avoid eddy-current heating and of low magnetic permeability to avoid distorting the induction fields providing the levitation.

  9. 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.

  10. Anode configuration for electrothermal/electromagnetic arcjet

    SciTech Connect

    Kuriki, K.; Shimizu, Y.; Nishida, E.

    1987-01-01

    To improve the performance of an MPD thruster in the range of a specific impulse near and above 1000 s, which corresponds to the electrothermal/electromagnetic hybrid mode of operation, the anode configuration was modified by changing: (1) the axial length of the metal anode and insulator nozzle, and (2) anode segments in the azimuthal direction as experimental parameters. The anode which was 5 percent the axial length of the nozzle resulted in a drastic improvement of thrust efficiency.

  11. Electromagnetic and Weak transitions in light nuclei

    SciTech Connect

    M. Viviani; L.E. Marcucci; A. Kievsky; S. Rosati; R. Schiavilla

    2002-09-01

    Recent advances in the study of the p -- d radiative and mu -- {sup 3}He weak capture processes by our group are presented and discussed. The trinucleon bound and scattering states have been obtained from variational calculations by expanding the corresponding wave functions in terms of correlated hyper-spherical harmonic functions. The electromagnetic and weak transition currents include one- and two-body operators. The accuracy achieved in these calculations allows for interesting comparisons with experimental data.

  12. New Electromagnetic Interference Shielding Material Demonstrated

    NASA Technical Reports Server (NTRS)

    Gaier, James R.

    1997-01-01

    A demonstration electromagnetic interference (EMI) shielding cover that has a potential mass savings in excess of 80 percent over conventional aluminum has been fabricated and tested. It was the culmination of a 3-yr effort involving Hughes Space and Communications (Los Angeles), Applied Sciences, Inc. (Cedarville, Ohio), and the NASA Lewis Research Center. The cover was fabricated from a composite of polycyanate ester resin and graphite fibers that had been chemically modified by intercalation to enhance their electrical conductivity.

  13. Geological-fracture mapping using electromagnetic geotomography

    SciTech Connect

    Ramirez, A.L.; Deadrick, F.J.; Lytle, R.J.

    1982-06-29

    This article describes the evaluation of a new geophysical technique used to map fractures between boreholes: electromagnetic geotomography used in conjunction with salt water tracers. An experiment has been performed in a granitic rock mass. Geotomographic images have been generated and compared with borehole geophysical data: neutron logs, acoustic velocity logs, caliper logs and acoustic televiewer records. Comparisons between the images and the geophysical logs indicate that clusters of fractures were detected but single fractures were not.

  14. Geological-fracture mapping using electromagnetic geotomography

    NASA Astrophysics Data System (ADS)

    Ramirez, A. L.; Deadrick, F. J.; Lytle, R. J.

    1982-06-01

    The evaluation of a new geophysical technique used to map fractures between boreholes is described: electromagnetic geotomography used in conjunction with salt water tracers. An experiment was performed in a granitic rock mass. Geotomographic images were generated and compared with borehole geophysical data: neutron logs, acoustic velocity logs, caliper logs and acoustic televiewer records. Comparisons between the images and the geophysical logs indicate that clusters of fractures were detected but single fractures were not.

  15. Electromagnetic or other directed energy pulse launcher

    SciTech Connect

    Ziolkowski, R.W.

    1990-09-25

    The physical realization of new solutions of wave propagation equations, such as Maxwell's equations and the scaler wave equation, produces localized pulses of wave energy such as electromagnetic or acoustic energy which propagate over long distances without divergence. This patent describes how the pulses are produced by driving each element of an array of radiating sources with a particular drive function so that the resultant localized packet of energy closely approximates the exact solutions and behaves the same.

  16. Rectangular Pulsed Laser-Electromagnetic Hybrid Accelerator

    SciTech Connect

    Kishida, Yoshiaki; Katayama, Masahiro; Horisawa, Hideyuki

    2010-10-13

    Experimental investigation of impulse-bit and propellant consumption rate, or mass shot, per single pulse discharge was conducted to characterize the thrust performance of the rectangular laser-electromagnetic hybrid acceleration thruster with various propellant materials. From the result, alumina propellant showed significantly superior performance. The largest values of the measured impulse-bit, specific impulse and thrust efficiency were 49 {mu}Nsec, 6,200 sec and 22%, respectively.

  17. Electromagnetic or other directed energy pulse launcher

    DOEpatents

    Ziolkowski, Richard W.

    1990-01-01

    The physical realization of new solutions of wave propagation equations, such as Maxwell's equations and the scaler wave equation, produces localized pulses of wave energy such as electromagnetic or acoustic energy which propagate over long distances without divergence. The pulses are produced by driving each element of an array of radiating sources with a particular drive function so that the resultant localized packet of energy closely approximates the exact solutions and behaves the same.

  18. Velocity damper for electromagnetically levitated materials

    DOEpatents

    Fox, Richard J.

    1994-01-01

    A system for damping oscillatory and spinning motions induced in an electromagnetically levitated material. Two opposed field magnets are located orthogonally to the existing levitation coils for providing a DC quadrupole field (cusp field) around the material. The material used for generating the DC quadrupole field must be nonconducting to avoid eddy-current heating and of low magnetic permeability to avoid distorting the induction fields providing the levitation.

  19. Velocity damper for electromagnetically levitated materials

    DOEpatents

    Fox, R.J.

    1994-06-07

    A system for damping oscillatory and spinning motions induced in an electromagnetically levitated material is disclosed. Two opposed field magnets are located orthogonally to the existing levitation coils for providing a DC quadrupole field (cusp field) around the material. The material used for generating the DC quadrupole field must be nonconducting to avoid eddy-current heating and of low magnetic permeability to avoid distorting the induction fields providing the levitation. 1 fig.

  20. Scaling the electromagnetically driven explosive shock simulator

    NASA Technical Reports Server (NTRS)

    Persh, Robert I.

    1987-01-01

    A heavy payload electromagnetically driven explosive shock simulator, referred to as EDESS-3, has been assembled and characterized at the Navel research Weapons Center. EDESS-3 is the logical outgrowth of the earlier EDESS 1 and 2 simulator work which explored the use of electrical pulse power technology for the generation of explosive like shocks. The features of the EDESS-3 are presented, and designs for the next generation of EDESS machines are introduced.

  1. Bobbing and kicks in electromagnetism and gravity

    SciTech Connect

    Gralla, Samuel E.; Harte, Abraham I.; Wald, Robert M.

    2010-05-15

    We study systems analogous to binary black holes with spin in order to gain some insight into the origin and nature of 'bobbing' motion and 'kicks' that occur in this system. Our basic tool is a general formalism for describing the motion of extended test bodies in an external electromagnetic field in curved spacetime and possibly subject to other forces. We first show that bobbing of exactly the type as observed in numerical simulations of the binary black hole system occurs in a simple system consisting of two spinning balls connected by an elastic band in flat spacetime. This bobbing may be understood as arising from the difference between a spinning body's 'lab frame centroid' and its true center of mass, and is purely 'kinematical' in the sense that it will appear regardless of the forces holding two spinning bodies in orbit. Next, we develop precise rules for relating the motion of charged bodies in a stationary external electromagnetic field in flat spacetime with the motion of bodies in a weakly curved stationary spacetime. We then consider the system consisting of two orbiting charges with magnetic dipole moment and spin at a level of approximation corresponding to 1.5 post-Newtonian order. Here we find that considerable amounts of momentum are exchanged between the bodies and the electromagnetic field; however, the bodies store this momentum entirely as ''hidden'' mechanical momentum, so that the interchange does not give rise to any net bobbing. The net bobbing that does occur is due solely to the kinematical spin effect, and we therefore argue that the net bobbing of the electromagnetic binary is not associated with possible kicks. We believe that this conclusion holds in the gravitational case as well.

  2. Electromagnetic wave scattering by an external field

    NASA Astrophysics Data System (ADS)

    Sannikov, S. S.

    1995-08-01

    The quantum electrodynamics of bilocal fields is used to calculate the triangular Feynman diagrams describing the elastic scattering of a classical electromagnetic wave by an external Coulomb field. The total contribution of the diagrams is nonzero because of the violation of both the Furry theorem (CP or T symmetries) and the Ward identities. The cross section for this scattering process is found for low and high energies. A comparison with Compton scattering and EulerHeisenberg scattering is given.

  3. Electromagnetic dark energy and gravitoelectrodynamics of superconductors

    NASA Astrophysics Data System (ADS)

    de Matos, Clovis Jacinto

    2008-02-01

    It is shown that Beck and Mackey electromagnetic model of dark energy in superconductors can account for the non-classical inertial properties of superconductors, which have been conjectured by the author to explain the Cooper pair’s mass excess reported by Cabrera and Tate. A new fundamental scale of nature (the Planck-Einstein scale) for gravitation in low temperature condensed matter is proposed to host the gravitoelectrodynamic properties of superconductors.

  4. Beyond the Kirchhoff approximation. II - Electromagnetic scattering

    NASA Technical Reports Server (NTRS)

    Rodriguez, Ernesto

    1991-01-01

    In a paper by Rodriguez (1981), the momentum transfer expansion was introduced for scalar wave scattering. It was shown that this expansion can be used to obtain wavelength-dependent curvature corrections to the Kirchhoff approximation. This paper extends the momentum transfer perturbation expansion to electromagnetic waves. Curvature corrections to the surface current are obtained. Using these results, the specular field and the backscatter cross section are calculated.

  5. Visualization of circuit card electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Zwillinger, Daniel

    1995-01-01

    Circuit boards are used in nearly every electrical appliance. Most board failures cause differing currents in the circuit board traces and components. This causes the circuit board to radiate a differing electromagnetic field. Imaging this radiated field, which is equivalent to measuring the field, could be used for error detection. Using estimates of the fields radiated by a low power digital circuit board, properties of known materials, and available equipment, we determined how well the following technologies could be used to visualize circuit board electromagnetic fields (prioritized by promise): electrooptical techniques, magnetooptical techniques, piezoelectric techniques, thermal techniques, and electrodynamic force technique. We have determined that sensors using the electrooptical effect (Pockels effect) appear to be sufficiently sensitive for use in a circuit board imaging system. Sensors utilizing the magnetooptical effect may also be adequate for this purpose, when using research materials. These sensors appear to be capable of achieving direct broadband measurements. We also reviewed existing electromagnetic field sensors. Only one of the sensors (recently patented) was specifically designed for circuit board measurements.

  6. Comparison between electroglottography and electromagnetic glottography

    SciTech Connect

    Titze, Ingo R.; Story, Brad H.; Burnett, Gregory C.; Holzrichter, John F.; Ng, Lawrence C.; Lea, Wayne A.

    2000-01-01

    Newly developed glottographic sensors, utilizing high-frequency propagating electromagnetic waves, were compared to a well-established electroglottographic device. The comparison was made on four male subjects under different phonation conditions, including three levels of vocal fold adduction (normal, breathy, and pressed), three different registers (falsetto, chest, and fry), and two different pitches. Agreement between the sensors was always found for the glottal closure event, but for the general wave shape the agreement was better for falsetto and breathy voice than for pressed voice and vocal fry. Differences are attributed to the field patterns of the devices. Whereas the electroglottographic device can operate only in a conduction mode, the electromagnetic device can operate in either the forward scattering (diffraction) mode or in the backward scattering (reflection) mode. Results of our tests favor the diffraction mode because a more favorable angle imposed on receiving the scattered (reflected) signal did not improve the signal strength. Several observations are made on the uses of the electromagnetic sensors for operation without skin contact and possibly in an array configuration for improved spatial resolution within the glottis. (c) 2000 Acoustical Society of America.

  7. ECSS Space Systems Electromagnetic Compatibility Handbook

    NASA Astrophysics Data System (ADS)

    Trougnou, L.

    2012-05-01

    This paper provides an overview of the final draft of the ECSS EMC Handbook (European Cooperation for Space Standardization, Space Systems Electromagnetic Compatibility Handbook), ECSS-E-HB-20-07A [1] that has been written by a working group involving representatives of European space industry, CNES (Centre National d'Études Spatiales) and ESA (European Space Agency). The purpose of the Handbook is to provide practical and helpful information for Electromagnetic Compatibility in the development of spacecraft equipment and systems. It gathers experience, know-how and lessons-learnt from the European space community with the aim to assist engineers throughout the design and development phases. The Handbook discusses system level activities and suggests design techniques, analyses and test methods. It also complements the ECSS-E-ST-20-07C standard (Space engineering - Electromagnetic compatibility) [2] by providing rationale for unit level test requirements. The ultimate objective of the Handbook is to guide engineers towards solid spacecraft EMC design and to assist them in the decision making process to avoid lengthy negotiations or late adjustments.

  8. Unify the electromagnetic force and gravitation

    NASA Astrophysics Data System (ADS)

    Ming, Zheng Sheng

    2013-04-01

    In the process of mankind investigate natural rule: people know four kinds of force: electromagnetic force, gravitation, weak force, and strong force. Meanwhile people use these four kinds force to explain all phenomena in the Nature. Obviously people do not know their mechanism of origin until now. On the other hand, these four kinds force is the difference showing form of one force, is not it? For solve these questions and find their mechanism of origin, I do some experiments and discover that the moving photons produce gravitation. This discovery shows the origin of gravitation. Meanwhile I also do experiments show that light is a particle, but is not a wave-particle duality. My experiments show that the elementary particles moving produce gravitation and electromagnetic force, this effect also produce wave effect. That is to say my experiment and calculate not only reveal the origin of gravitation, but also reveal the origin of electric charge and magnetic force. Base on this I first unify the electromagnetic force and gravitation. The more detail see below website: https://www.lap-publishing.com/catalog/details/store/gb/book/978-3-8473-2658-8/mechanism-of-interaction-in-moving-matter

  9. Unify the electromagnetic force and gravitation

    NASA Astrophysics Data System (ADS)

    Sheng Ming, Zheng

    2013-04-01

    In the process of mankind investigate natural rule: people know four kinds of force: electromagnetic force, gravitation, weak force, and strong force. Meanwhile people use these four kinds force to explain all phenomena in the Nature. Obviously people do not know their mechanism of origin until now. On the other hand, these four kinds force is the difference showing form of one force, is not it? For solve these questions and find their mechanism of origin, I do some experiments and discover that the moving photons produce gravitation. This discovery shows the origin of gravitation. Meanwhile I also do experiments show that light is a particle, but is not a wave-particle duality. My experiments show that the elementary particles moving produce gravitation and electromagnetic force, this effect also produce wave effect. That is to say my experiment and calculate not only reveal the origin of gravitation, but also reveal the origin of electric charge and magnetic force. Base on this I first unify the electromagnetic force and gravitation. The more detail see below website: https://www.lap-publishing.com/catalog/details/store/gb/book/978-3-8473-2658-8/mechanism-of-interaction-in-moving-matter.

  10. Advanced electromagnetic methods for aerospace vehicles

    NASA Technical Reports Server (NTRS)

    Balanis, Constantine A.; El-Sharawy, El-Budawy; Hashemi-Yeganeh, Shahrokh; Aberle, James T.; Birtcher, Craig R.

    1991-01-01

    The Advanced Helicopter Electromagnetics is centered on issues that advance technology related to helicopter electromagnetics. Progress was made on three major topics: composite materials; precipitation static corona discharge; and antenna technology. In composite materials, the research has focused on the measurements of their electrical properties, and the modeling of material discontinuities and their effect on the radiation pattern of antennas mounted on or near material surfaces. The electrical properties were used to model antenna performance when mounted on composite materials. Since helicopter platforms include several antenna systems at VHF and UHF bands, measuring techniques are being explored that can be used to measure the properties at these bands. The effort on corona discharge and precipitation static was directed toward the development of a new two dimensional Voltage Finite Difference Time Domain computer program. Results indicate the feasibility of using potentials for simulating electromagnetic problems in the cases where potentials become primary sources. In antenna technology the focus was on Polarization Diverse Conformal Microstrip Antennas, Cavity Backed Slot Antennas, and Varactor Tuned Circular Patch Antennas. Numerical codes were developed for the analysis of two probe fed rectangular and circular microstrip patch antennas fed by resistive and reactive power divider networks.

  11. A general theory of DC electromagnetic launchers

    NASA Astrophysics Data System (ADS)

    Engel, Thomas G.; Timpson, Erik J.

    2015-08-01

    The non-linear, transient operation of DC electromagnetic launchers (EMLs) complicates their theoretical understanding and prevents scaling studies and performance comparisons without the aid of detailed numerical models. This paper presents a general theory for DC electromagnetic launchers that has simplified these tasks by identifying critical EML parameters and relationships affecting the EML's voltage, current, and power scaling, as well as its performance and energy conversion efficiency. EML parameters and relationships discussed in this paper include the specific force, the operating mode, the launcher constant, the launcher characteristic velocity, the contact characteristic velocity, the energy conversion efficiency, and the kinetic power and voltage-current scaling relationship. The concepts of the ideal EML, same-scale comparisons, and EML impedance are discussed. This paper defines conditions needed for the EML to operate in the steady-state. A comparison of the general theory with experimental results of several different types of DC (i.e., non-induction) electromagnetic launchers ranging from medium velocity (100's m/s) to high velocity (1000's m/s) is performed. There is good agreement between the general theory and the experimental results.

  12. Electromagnetic treatment of the multipole resonance probe

    NASA Astrophysics Data System (ADS)

    Lapke, Martin; Mussenbrock, Thomas; Brinkmann, Ralf Peter

    2009-10-01

    We present an electromagnetic model of the ``multipole resonance probe'' (MRP)-- a diagnostic concept which enables the simultaneous determination of plasma density, electron temperature, and collision rate in low-pressure gas discharges. The MRP is a radio-frequency driven probe of particular spherical design. In an idealized version the probe consists of two dielectrically shielded, conducting hemispheres. Driven by a radio-frequency source, the hemispheres are powered symmetrically. An analysis of the absorption spectrum shows a multitude of resonances, which allows for an analytical evaluation of the measured signal. The signal provides information on the distribution of the plasma in the probe's vicinity, from which the values of electron density, electron temperature and collision rate can be inferred. In this contribution the MRP will be modeled electromagnetically. Based on a comparision between full electromagnetic and electrostatic treatment, we show that a previously presented electrostatic treatment [1] was well justified.[4pt] [1] M.Lapke et al., Appl. Phys. Lett. 93, 051502 (2008)

  13. Electromagnetic shielding mats: facts and fiction.

    PubMed

    Leitgeb, N; Cech, R

    2007-01-01

    The use of electricity is accompanied by electric and magnetic fields which, intended or not, became a part of our environment. However, fear from environmental electromagnetic fields (EMFs) is widespread and so is business with fear. A number of more or less serious products including miracle products are placed on the market partly at excessive costs. By numerical simulation the efficiency of electromagnetic shielding mats was investigated and claims of manufacturers and their cited expert opinions checked. It could be shown that such products do not fulfil the justified expectations of customers, neither in the extremely low frequency (ELF) nor in the radiofrequency (RF) range. On the contrary, these mats usually make things even worse. The connection to ground, if available, might increase the belief on shielding efficiency, but in fact it even enhances fields instead of improving shielding. The electric conductivity of the mat material plays a minor role in the ELF range and enhances field increase in the RF range. It can not explain the enormous price differences. It could be shown that positive reports can be explained by result picking and exceptional arrangements of selected field sources. Overall, the investigation showed that manufacturer's claims about the shielding effectiveness are misleading and fool the customers about the real situation. Therefore, acquisition and use of electromagnetic shielding mats must be strongly discouraged. PMID:17151012

  14. Basic Discoveries in Electromagnetic Field Visualization

    NASA Astrophysics Data System (ADS)

    Shindo, Daisuke

    2014-01-01

    Basic discoveries in the electromagnetic field visualization are presented, mentioning the late Dr. A. Tonomura's significant achievements in this field. First, the discovery of the electron biprism interferences by G. Mllenstedt and his colleagues was noted. Having studied Mllenstedt's interference experiments, A. Tonomura and his colleagues have extended the electron holography system to clearly prove the physical reality of vector potentials, the so-called Aharonov-Bohm effect. They also succeeded in observing the dynamic motions of magnetic flux quanta (fluxons) in a superconducting Nb film. In a joint research with A. Tonomura, we succeeded in visualizing a fluxon pinned by an insulating particle in a high-Tc Y-Ba-Cu-O superconductor by combining electron holography and scanning ion microscopy. As the study of a scalar potential, the visualization of the orbits of electron-induced secondary electrons around positively charged biological specimens was noted. Finally, although the electromagnetic field analysis using electron holography on the basis of Maxwell's equations seems to be promising, it is pointed out that there have been some controversies on the interpretation and treatment of electromagnetic field.

  15. Electromagnetic force and torque in ponderable media.

    PubMed

    Mansuripur, Masud

    2008-09-15

    Maxwell's macroscopic equations combined with a generalized form of the Lorentz law of force are a complete and consistent set of equations. Not only are these five equations fully compatible with special relativity, they also conform with conservation laws of energy, momentum, and angular momentum. We demonstrate consistency with the conservation laws by showing that, when a beam of light enters a magnetic dielectric, a fraction of the incident linear (or angular) momentum pours into the medium at a rate determined by the Abraham momentum density, E x H/c(2), and the group velocity V(g) of the electromagnetic field. The balance of the incident, reflected, and transmitted momenta is subsequently transferred to the medium as force (or torque) at the leading edge of the beam, which propagates through the medium with velocity V(g). Our analysis does not require "hidden" momenta to comply with the conservation laws, nor does it dissolve into ambiguities with regard to the nature of electromagnetic momentum in ponderable media. The linear and angular momenta of the electromagnetic field are clearly associated with the Abraham momentum, and the phase and group refractive indices (n(p) and n(g)) play distinct yet definitive roles in the expressions of force, torque, and momentum densities. PMID:18795019

  16. Electromagnetic damper design using a multiphysics approach

    NASA Astrophysics Data System (ADS)

    Stabile, Alessandro; Aglietti, Guglielmo S.; Richardson, Guy

    2015-04-01

    Electromagnetic dampers (EMD) have been widely studied and designed in the control of vibrating structures. Yet, their use for space applications has been almost negligible, due mainly to their high ratio of system mass over damping force produced. The development of shunted circuits, and in particular negative impedances, has allowed higher currents to flow in the device, thus obtaining an increased damping performance. However, the need for a thermal analysis has become crucial in order to evaluate the power and temperature limits of EMDs, and hence allow a more efficient optimization of the whole device. This paper presents a multiphysics Finite Element Analysis (FEA) of an EMD in which the thermal domain is integrated with the electromagnetic and mechanical domains. The influence of the temperature on the device parameters and overall performance in the operative temperature and frequency range of a space mission is shown. It follows a design optimization of an electromagnetic shunted damper for 5-kg SDOF to obtain a second-order filter. In particular, the analytical results are compared with the typical transfer function of a viscoelastic material. This paper demonstrates the feasibility to achieve the same slope of -40 dB/dec while considerably decreasing the magnitude of the characteristic resonance peak of viscoelastic materials.

  17. Experiments for electromagnetic levitation in microgravity

    NASA Technical Reports Server (NTRS)

    Willnecker, R.; Egry, I.

    1990-01-01

    Containerless processing is a promising research tool for investigating the properties of undercooled melts and their solidification. For conducting samples RF-electromagnetic levitation offers the possibility to obtain large undercoolings by avoiding heterogeneous nucleation at container walls. On earth, however, strong magnetic fields are needed to compensate the gravitational force which imposes a lower limit on the available temperatures and on the accessible undercooling range. Under microgravity conditions the magnetic positioning fields can be minimized and hence, undercooling becomes feasible under ultra-high vacuum conditions and lower temperatures become accessible. In contrast to other undercooling and solidification techniques, electromagnetic levitation allows for diagnostic measurements during the early steps of nucleation and phase selection. Experiments cover a wide field of research topics: nucleation, directional solidification at high velocities, generation of metastable phases, evolution of microstructures, properties of undercooled liquids. Examples from these classes including experiments selected for the IML-2 mission are discussed with emphasis on technical requirements. An overview is given on the German TEMPUS (electromagnetic levitation facility) program.

  18. Electromagnetic Compatibility in Nuclear Power Plants

    SciTech Connect

    Ewing, P.D.; Kercel, S.W.; Korsah, K.; Wood, R.T.

    1999-08-29

    Electromagnetic compatibility (EMC) has long been a key element of qualification for mission critical instrumentation and control (I&C) systems used by the U.S. military. The potential for disruption of safety-related I&C systems by electromagnetic interference (EMI), radio-frequency interference (RFI), or power surges is also an issue of concern for the nuclear industry. Experimental investigations of the potential vulnerability of advanced safety systems to EMI/RFI, coupled with studies of reported events at nuclear power plants (NPPs) that are attributed to EMI/RFI, confirm the safety significance of EMC for both analog and digital technology. As a result, Oak Ridge National Laboratory has been engaged in the development of the technical basis for guidance that addresses EMC for safety-related I&C systems in NPPs. This research has involved the identification of engineering practices to minimize the potential impact of EMI/RFI and power surges and an evaluation of the ambient electromagnetic environment at NPPs to tailor those practices for use by the nuclear industry. Recommendations for EMC guidance have been derived from these research findings and are summarized in this paper.

  19. Models of electromagnetic properties of composite media

    NASA Astrophysics Data System (ADS)

    Liu, Jin

    Electromagnetic composite materials have attracted much interest in recent years, due to their desirable microwave and optical applications. One class of these is negative refractive index materials, or double negative materials, in which both permittivity and permeability of materials are simultaneously negative. Many exciting potential applications of double negative materials have been proposed, such as the perfect lens and the cloaking device. Here, a simple-cubic lattice of identical, homogeneous or coated non-metallic spherical particles embedded in a matrix is analyzed. One contribution of this work is the derivation of an analytical formula for the threshold dielectric loss angle of spherical inclusions, above which DNG behavior of the system is extinguished. In addition, analytical formulas are derived from which double negative bandwidth of a simple-cubic lattice of identical, magnetodielectric homogeneous or coated spheres can be determined. Another case of interest is nanocomposites, which commonly consist of nanoparticles embedded in a polymer matrix. These materials show superior dielectric or mechanical performance by taking advantage of the merits of their individual non-hybrid components. In one manifestation, diblock copolymers can be utilized to spatially separate nanoparticles by incorporating them in one block, preferentially, to form a long-range ordered structure. By designing this structure, the electromagnetic properties can be tailored for potential applications in novel devices. Here, molecular dynamics of polymer matrices and nanocomposites is analyzed by parametric modeling of their dielectric spectra, supporting design of a composite with desired electromagnetic properties.

  20. [Combined biological effect of electromagnetic fields and chemical substances (toxic)].

    PubMed

    Kamedula, M; Kamedula, T

    1996-01-01

    The authors present results of own measurements and examinations as well as the literature data on the occurrence and effect of direct, low and high frequency electromagnetic fields and chemicals. In real working conditions and in experimental conditions, the following relations can be observed: 1) concomitant occurrence of electromagnetic fields and chemicals, e.g. processes of electrolysis, inductive and dielectric heating; 2) experimental studies of combined effect of electromagnetic fields and chemicals on e.g. cancer development: 3) drug effect modified by electromagnetic fields; 4) effect of chemicals produced in materials under the influence of electromagnetic fields. There are only a few publications on medical examinations of workers exposed simultaneously to electromagnetic fields and chemicals. However, even in those reported studies, an attempt to distinguish changes in the health state due to electromagnetic fields, and due to chemicals has field. The studies of the effect of electromagnetic fields which modify the effect of carcinogenic substances have not yielded unequivocal results. Electromagnetic fields may modify significantly the effect of some psychotropic and hormonal drugs. Under the influence of pyrolisis, induced by thermal effect of electromagnetic fields, toxic substances or substances with harmful biological effect may occur in some materials. PMID:8760513

  1. Division of the momentum of electromagnetic waves in linear media into electromagnetic and material parts.

    PubMed

    Saldanha, Pablo L

    2010-02-01

    It is proposed a natural and consistent division of the momentum of electromagnetic waves in linear, non-dispersive and non-absorptive dielectric and magnetic media into material and electromagnetic parts. The material part is calculated using directly the Lorentz force law and the electromagnetic momentum density has the form epsilon(0)E x B, without an explicit dependence on the properties of the media. The consistency of the treatment is verified through the obtention of a correct momentum balance equation in many examples and showing the compatibility of the division with the Einstein's theory of relativity by the use of a gedanken experiment. An experimental prediction for the radiation pressure on mirrors immersed in linear dielectric and magnetic media is also made. PMID:20174054

  2. Method and apparatus for electromagnetically braking a motor

    NASA Technical Reports Server (NTRS)

    Davis, Donald R. (Inventor); Radford, Nicolaus A (Inventor); Permenter, Frank Noble (Inventor); Parsons, Adam H (Inventor); Mehling, Joshua S (Inventor)

    2011-01-01

    An electromagnetic braking system and method is provided for selectively braking a motor using an electromagnetic brake having an electromagnet, a permanent magnet, a rotor assembly, and a brake pad. The brake assembly applies when the electromagnet is de-energized and releases when the electromagnet is energized. When applied the permanent magnet moves the brake pad into frictional engagement with a housing, and when released the electromagnet cancels the flux of the permanent magnet to allow a leaf spring to move the brake pad away from the housing. A controller has a DC/DC converter for converting a main bus voltage to a lower braking voltage based on certain parameters. The converter utilizes pulse-width modulation (PWM) to regulate the braking voltage. A calibrated gap is defined between the brake pad and permanent magnet when the brake assembly is released, and may be dynamically modified via the controller.

  3. A method of measuring dynamic strain under electromagnetic forming conditions

    NASA Astrophysics Data System (ADS)

    Chen, Jinling; Xi, Xuekui; Wang, Sijun; Lu, Jun; Guo, Chenglong; Wang, Wenquan; Liu, Enke; Wang, Wenhong; Liu, Lin; Wu, Guangheng

    2016-04-01

    Dynamic strain measurement is rather important for the characterization of mechanical behaviors in electromagnetic forming process, but it has been hindered by high strain rate and serious electromagnetic interference for years. In this work, a simple and effective strain measuring technique for physical and mechanical behavior studies in the electromagnetic forming process has been developed. High resolution (˜5 ppm) of strain curves of a budging aluminum tube in pulsed electromagnetic field has been successfully measured using this technique. The measured strain rate is about 105 s-1, which depends on the discharging conditions, nearly one order of magnitude of higher than that under conventional split Hopkins pressure bar loading conditions (˜104 s-1). It has been found that the dynamic fracture toughness of an aluminum alloy is significantly enhanced during the electromagnetic forming, which explains why the formability is much larger under electromagnetic forging conditions in comparison with conventional forging processes.

  4. A method of measuring dynamic strain under electromagnetic forming conditions.

    PubMed

    Chen, Jinling; Xi, Xuekui; Wang, Sijun; Lu, Jun; Guo, Chenglong; Wang, Wenquan; Liu, Enke; Wang, Wenhong; Liu, Lin; Wu, Guangheng

    2016-04-01

    Dynamic strain measurement is rather important for the characterization of mechanical behaviors in electromagnetic forming process, but it has been hindered by high strain rate and serious electromagnetic interference for years. In this work, a simple and effective strain measuring technique for physical and mechanical behavior studies in the electromagnetic forming process has been developed. High resolution (∼5 ppm) of strain curves of a budging aluminum tube in pulsed electromagnetic field has been successfully measured using this technique. The measured strain rate is about 10(5) s(-1), which depends on the discharging conditions, nearly one order of magnitude of higher than that under conventional split Hopkins pressure bar loading conditions (∼10(4) s(-1)). It has been found that the dynamic fracture toughness of an aluminum alloy is significantly enhanced during the electromagnetic forming, which explains why the formability is much larger under electromagnetic forging conditions in comparison with conventional forging processes. PMID:27131683

  5. Nuclear electromagnetic pulse and the electric power system

    NASA Astrophysics Data System (ADS)

    Legro, J. R.; Reed, T. J.

    A single, high-altitude nuclear detonation over the continental United States can expose large geographic areas to transient, electromagnetic pulse (EMP). The initial electromagnetic fields produced by this event have been defined as high-altitude electromagnetic pulse (HEMP). Later-time, low frequency fields have been defined as magnetohydrodynamic-electromagnetic pulse (MHD-EMP). Nuclear detonations at, or near the surface of the earth can also produce transient EMP. These electromagnetic phenomena have been defined as source region electromagnetic pulse (SREMP). The Division of Electric Energy Systems (EES) of the United States Department of Energy (DOE) has formulated and implemented a program Plan to assess the possible effects of the above nuclear EMP on civilian electric power systems. This unclassified research effort is under the technical leadership of the Oak Ridge National Laboratory. A brief perspective of EMP phenomenology and important interaction issues for power systems based on research performed by Westinghouse Advanced Systems Technology is given.

  6. Hemming of Aluminum Alloy Sheets Using Electromagnetic Forming

    NASA Astrophysics Data System (ADS)

    Shang, Jianhui; Wilkerson, Larry; Hatkevich, Steve

    2011-11-01

    Hemming is usually the last stage of production for automotive closures, and therefore has a critical effect on the quality of the final assemblies. The insufficient formability of aluminum alloys creates a considerable problem in the hemming process. To address this issue, electromagnetic forming was utilized to hem aluminum alloy sheets. Electromagnetic forming is a high strain rate forming process that is currently being investigated by both academia and industry. Past studies have shown that the formability of metals can be significantly improved during electromagnetic forming, which benefits the hemming of aluminum alloys. This article presents the experimental results of hemming Al 6061-T6 sheets using electromagnetic forming. The effects of the parameters of electromagnetic hemming on the hem quality are discussed. In addition, the numerical simulation results of electromagnetic hemming are presented to enhance the understanding of the process and to determine the efficacy on an industrial scale.

  7. Kinetic theory of electromagnetic ion waves in relativistic plasmas

    SciTech Connect

    Marklund, Mattias; Shukla, Padma K.

    2006-09-15

    A kinetic theory for electromagnetic ion waves in a cold relativistic plasma is derived. The kinetic equation for the broadband electromagnetic ion waves is coupled to the slow density response via an acoustic equation driven by a ponderomotive force-like term linear in the electromagnetic field amplitude. The modulational instability growth rate is derived for an arbitrary spectrum of waves. The monochromatic and random phase cases are studied.

  8. Electromagnetic Field Scattering on rf-SQUID Based Metasurfaces

    NASA Astrophysics Data System (ADS)

    Raputo, J. G.; Gabitov, I. R.; Kudyshev, Zh.; Kupaev, T.; Maimistov, A. I.

    2015-09-01

    Electromagnetic field scattering on a 2D array of rf-SQUIDs is considered. We show that the scattering changes for large amplitudes of the incident electromagnetic wave; above a critical amplitude, two different refraction states occur (bistability). In particular, for these two states, the transmitted wave polarization and angle of refraction are different. One could then switch the direction of propagation of the electromagnetic wave and its polarization with a "thin film", whose thickness is much smaller than the wavelength.

  9. Electromagnetic servoing-a new tracking paradigm.

    PubMed

    Reichl, Tobias; Gardiazabal, José; Navab, Nassir

    2013-08-01

    Electromagnetic (EM) tracking is highly relevant for many computer assisted interventions. This is in particular due to the fact that the scientific community has not yet developed a general solution for tracking of flexible instruments within the human body. Electromagnetic tracking solutions are highly attractive for minimally invasive procedures, since they do not require line of sight. However, a major problem with EM tracking solutions is that they do not provide uniform accuracy throughout the tracking volume and the desired, highest accuracy is often only achieved close to the center of tracking volume. In this paper, we present a solution to the tracking problem, by mounting an EM field generator onto a robot arm. Proposing a new tracking paradigm, we take advantage of the electromagnetic tracking to detect the sensor within a specific sub-volume, with known and optimal accuracy. We then use the more accurate and robust robot positioning for obtaining uniform accuracy throughout the tracking volume. Such an EM servoing methodology guarantees optimal and uniform accuracy, by allowing us to always keep the tracked sensor close to the center of the tracking volume. In this paper, both dynamic accuracy and accuracy distribution within the tracking volume are evaluated using optical tracking as ground truth. In repeated evaluations, the proposed method was able to reduce the overall error from 6.64±7.86 mm to a significantly improved accuracy of 3.83±6.43 mm. In addition, the combined system provides a larger tracking volume, which is only limited by the reach of the robot and not the much smaller tracking volume defined by the magnetic field generator. PMID:23911947

  10. Modellingof Electromagnetic Acoustic Transducers Operatingon Ferromagnetic Materials

    NASA Astrophysics Data System (ADS)

    Ribichini, R.; Cegla, F.; Nagy, P. B.; Cawley, P.

    2010-02-01

    The contactless nature of Electromagnetic Acoustic Transducers (EMATs) offers a series of advantages over traditional piezoelectric transducers, but these features are counter-balanced by their relatively low signal-to-noise ratio. The implication is that full exploitation of EMATs needs detailed modelling of their operation. A finite element model, accounting for the main transduction mechanisms, has been developed to allow the optimization of the transducers. Magnetostriction is included and described through an analogy with piezoelectricity. The model is used to predict the performance of a practical EMAT and the results are validated against experiments.

  11. Generalized Terminal Modeling of Electromagnetic Interference

    SciTech Connect

    Baisden, Andrew Carson; Boroyevich, Dushan; Wang, Fei

    2010-01-01

    Terminal models have been used for various applications. In this paper, a three-terminal model is proposed for electromagnetic-interference (EMI) characterization. The model starts with a power electronic system at a particular operating condition and creates a unique linearized equivalent circuit. Impedances and current/voltage sources define the noise throughout the entire EMI frequency spectrum. All parameters needed to create the model are clearly defined to ensure convergence and maximize accuracy. In addition, the accuracy of the model is confirmed up to 100 MHz for a dc-dc boost converter using both simulation and experimental validation.

  12. Artificial Retina Project: Electromagnetic and Thermal Effects

    SciTech Connect

    Lazzi, Gianluca

    2014-08-29

    This award supported the investigation on electromagnetic and thermal effects associated with the artificial retina, designed in collaboration with national laboratories, universities, and private companies. Our work over the two years of support under this award has focused mainly on 1) Design of new telemetry coils for optimal power and data transfer between the implant and the external device while achieving a significant size reduction with respect to currently used coils; 2) feasibility study of the virtual electrode configuration 3) study the effect of pulse shape and duration on the stimulation efficacy.

  13. Bifunctional metasurface for electromagnetic cloaking and illusion

    NASA Astrophysics Data System (ADS)

    Xiang, Nan; Cheng, Qiang; Chen, Hai Bing; Zhao, Jie; Jiang, Wei Xiang; Ma, Hui Feng; Cui, Tie Jun

    2015-09-01

    We present the demonstration of a bifunctional metasurface in the microwave regime. The metasurface is composed of periodically arranged anisotropic elements, with various electromagnetic responses according to polarizations of incident waves. When the metasurface is wrapped on a moderately sized metallic cylinder, we show that it acts as an illusion coating for one polarization but a mantle cloak for another polarization. Numerical simulations have been carried out to demonstrate the illusion and cloaking properties of the metasurface, which open up new and intriguing applications in multifunctional metadevices.

  14. Electromagnetic and gravitational radiation from massless particles

    NASA Astrophysics Data System (ADS)

    Gal'Tsov, D. V.

    We demonstrate that full description of both electromagnetic and gravitational radiation from massless particles lies outside the scope of classical theory. Synchrotron radiation from the hypothetical massless charge in quantum electrodynamics in external magnetic field has finite total power while the corresponding classical formula diverges in the massless limit. We argue that in both cases classical theory describes correctly only the low-frequency part of the spectra, while the total power diverges because of absence of the UV frequency cutoff. Failure of description of gravitational radiation from massless particles by classical General Relativity may be considered as another appeal for quantization of gravity apart from the problem of singularities...

  15. Stationkeeping with two-way electromagnetic launchers

    NASA Astrophysics Data System (ADS)

    Nordley, Gerald David

    1994-11-01

    This study is motivated by previous proposals for electromagnetic launchers (EML) to launch payloads from the moon and space stations. With the advent of modern computer-controlled attitude and velocity control systems on the payload it is possible for EML to decelerate as well as launch payloads. In view of this, a two-way EML-equipped design to generate significant outward velocity without loss of reaction mass is realized. This model indicates that, in-addition to L1 stationkeeping, satellite could be pushed away from planets, or planets away from the sun, without loss of reaction mass.

  16. An investigation of electromagnetic launcher repeatability

    NASA Astrophysics Data System (ADS)

    Heyse, Mark W.; Cornette, James B.; Brown, Jere L.

    1992-07-01

    Electromagnetic launcher (EML) performance repeatability has been identified as a potential development issue for several years. Investigation of this issue has been difficult because an EML that is powered on a relatively continuous basis to provide long duration operation has not been available. A battery charged capacitor power system has enabled long duration, 6 to 7 seconds, EML experiments. This paper provides a summary of an experiment to investigate EML launch to launch performance consistency. A series of 8 ten-shot bursts, each separated by 15 to 30 minutes, performed in a single day using a single set of bore materials is the subject of this paper.

  17. An investigation of electromagnetic launch repeatability

    NASA Astrophysics Data System (ADS)

    Cornette, James B.; Heyse, Mark W.; Brown, Jere L.

    1993-01-01

    Electromagnetic launcher (EML) performance repeatability has been identified as a potential development issue for several years. Investigation of this issue has been difficult because an EML that is powered on a relatively continuous basis to provide long duration operation has not been available. A battery charged capacitor power system has enabled long duration, 6 to 7 seconds, EML experiments. This paper provides a summary of an experiment to investigate EML launch to launch performance consistency. A series of 8 ten-shot bursts, each separated by 15 to 30 minutes, performed in a single day using a single set of bore materials is the subject of this paper.

  18. Modeling of Electromagnetic Damper for Automobile Suspension

    NASA Astrophysics Data System (ADS)

    Kawamoto, Yasuhiro; Suda, Yoshihiro; Inoue, Hirofumi; Kondo, Takuhiro

    In this paper, the modeling of the electromagnetic damper (EMD) for automobile suspension is presented and the validation of the model is demonstrated by comparing the numerical results with the experimental results obtained using shaker tests. EMD is used as an active suspension and controlled to have output force calculated from velocities of sprung and unsprung masses. The formulation of EMD system for active suspensions is first developed, and the validation of the EMD model is demonstrated by experiments of the EMD for automobile suspensions. The validity of the formulation of the EMD developed in this investigation is shown for the frequency responses as well as energy balance for its active use.

  19. Electromagnetic modulation of monochromatic neutrino beams

    NASA Astrophysics Data System (ADS)

    Barabanov, A. L.; Titov, O. A.

    2015-08-01

    A possibility to produce a modulated monochromatic neutrino beam is discussed. Monochromatic neutrinos can be obtained in electron capture by nuclei of atoms or ions, in particular, by nuclei of hydrogen-like ions. It is shown that monochromatic neutrino beam from such hydrogen-like ions with nuclei of non-zero spin can be modulated because of different probabilities of electron capture from hyperfine states. Modulation arises by means of inducing of electromagnetic transitions between the hyperfine states. Requirements for the hydrogen-like ions with necessary properties are discussed. A list of the appropriate nuclei for such ions is presented.

  20. Metamaterial particles for electromagnetic energy harvesting

    NASA Astrophysics Data System (ADS)

    Ramahi, Omar M.; Almoneef, Thamer S.; AlShareef, Mohammed; Boybay, Muhammed S.

    2012-10-01

    Metamaterials are typically made of an ensemble of electrically small resonators such as metallic loops. The fact that such particles resonate individually to generate a bulk material behavior having enhanced constitutive parameters is essentially indicative of these particles' ability to collect energy. We show that such particles act as energy collectors when a resistive load is inserted within the particle's gap. A proof of concept is provided using a 5.8 GHz field and a split-ring resonator (SRR) as the electromagnetic energy collecting cell. Numerical simulation for a 9 × 9 SRR array shows the effectiveness of an SRR array as an energy collector plate.

  1. Electromagnetic evaluation of reinforced concrete structure

    NASA Astrophysics Data System (ADS)

    Chady, T.; Frankowski, P.

    2013-01-01

    The purpose of this paper is to present the new electromagnetic system for detection and evaluation of steel bars in reinforced concrete structures. A differential eddy current transducers and system with lock-in amplifier are proposed for this purpose. Studies show that, the shape of output voltage module signal provides information about main parameters of reinforcement. Selected Data Mining algorithms are used to search associations between output waveform and diameter, location and steel class of rebars. The experimental verification of the developed technique is done and the selected, promising results are presented.

  2. Survey of nucleon electromagnetic form factors

    SciTech Connect

    Perdrisat, Charles F.; Punjabi, Vina A.

    2011-09-20

    There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has been greatly improved by performing double polarization experiments, in compar- ison with previous unpolarized data. Here we review the experimental data base in view of the new results for the proton, and neutron, obtained at MIT-Bates, MAMI, and JLab. The rapid evolution of phenomenological models triggered by these high-precision experiments will be discussed.

  3. Cracking of compact objects with electromagnetic field

    NASA Astrophysics Data System (ADS)

    Azam, M.; Mardan, S. A.; Rehman, M. A.

    2015-09-01

    In this paper, we investigate the role of electromagnetic field on the stability regions of charged self-gravitating compact objects by using the concept of cracking. For this purpose, we have applied local density perturbation scheme to the hydrostatic equilibrium equation as well as on physical parameters involved in the model. In particular, we have examined the cracking of charged compact objects like PSR J1614-2230, PSR J1903+327, Vela X-1, SMC X-1 and Cen X-3 with different values of charge. We conclude that these objects exhibit cracking and stability regions decreases with the increase of charge.

  4. Source identification in time domain electromagnetics

    NASA Astrophysics Data System (ADS)

    Benoit, J.; Chauvière, C.; Bonnet, P.

    2012-04-01

    In this paper, we introduce two numerical methods to get an electric source that gives a specified electromagnetic field some time after the source starts emitting. The first one is called the Time Reversal Method (TRM) and originates from acoustics and the second one is called Linear Combination of Configuration Fields (LCCF) and consists in constructing and solving a linear problem in order to find a possible required source. In this paper, we show on 1D and 2D examples that the last method gives lower relative errors when compared with the time reversal method.

  5. Electromagnetic interference onboard an electrically propelled spacecraft

    NASA Technical Reports Server (NTRS)

    Macie, T. W.; Whittlesey, A. C.

    1973-01-01

    Electric and magnetic interference generated by a power conditioner and ion thruster were measured at JPL. Test results were judged by comparing the measured levels to the levels defined by the solar electric propulsion (SEP) specification that was derived from the existing mission oriented Viking-Orbiter 1975 and Mariner-Jupiter-Saturn 1977 electromagnetic compatibility specifications. In many areas the measured interference was excessive. In some cases, the cause of interference was identified. It was concluded that it should be possible on future designs to improve the EMI characteristics greatly at a modest penalty to weight and efficiency.

  6. Intrinsic operators for the electromagnetic nuclear current

    SciTech Connect

    J. Adam, Jr.; H. Arenhovel

    1996-09-01

    The intrinsic electromagnetic nuclear meson exchange charge and current operators arising from a separation of the center-of-mass motion are derived for a one-boson-exchange model for the nuclear interaction with scalar, pseudoscalar and vector meson exchange including leading order relativistic terms. Explicit expressions for the meson exchange operators corresponding to the different meson types are given in detail for a two-nucleon system. These intrinsic operators are to be evaluated between intrinsic wave functions in their center-of-mass frame.

  7. Electromagnetic Torque in Tokamaks with Toroidal Asymmetries

    NASA Astrophysics Data System (ADS)

    Logan, Nikolas Christopher

    Toroidal rotation and rotation shear strongly influences stability and confinement in tokamaks. Breaking of the toroidal symmetry by fields orders of magnitude smaller than the axisymmetric field can, however, produce electromagnetic torques that significantly affect the plasma rotation, stability and confinement. These electromagnetic torques are the study of this thesis. There are two typical types of electromagnetic torques in tokamaks: 1) "resonant torques" for which a plasma current defined by a single toroidal and single poloidal harmonic interact with external currents and 2) "nonresonant torques" for which the global plasma response to nonaxisymmetric fields is phase shifted by kinetic effects that drive the rotation towards a neoclassical offset. This work describes the diagnostics and analysis necessary to evaluate the torque by measuring the rate of momentum transfer per unit area in the vacuum region between the plasma and external currents using localized magnetic sensors to measure the Maxwell stress. These measurements provide model independent quantification of both the resonant and nonresonant electromagnetic torques, enabling direct verification of theoretical models. Measured values of the nonresonant torque are shown to agree well with the perturbed equilibrium nonambipolar transport (PENT) code calculation of torque from cross field transport in nonaxisymmetric equilibria. A combined neoclassical toroidal viscosity (NTV) theory, valid across a wide range of kinetic regimes, is fully implemented for the first time in general aspect ratio and shaped plasmas. The code captures pitch angle resonances, reproducing previously inaccessible collisionality limits in the model. The complete treatment of the model enables benchmarking to the hybrid kinetic MHD stability codes MARS-K and MISK, confirming the energy-torque equivalency principle in perturbed equilibria. Experimental validations of PENT results confirm the torque applied by nonaxisymmetric coils is often proportional to the energy put into the dominant ideal MHD kink mode. This reduces the control of nonresonant torque to a single mode model, enabling efficient feed forward optimization of applied fields. Initial results including the anisotropic kinetic pressure tensor directly in the plasma eigenmode calculations are presented here, and may eventually provide accurate metrics for multimodal coupling similar to the established single mode metrics.

  8. Design and testing of an electromagnetic coupling

    NASA Technical Reports Server (NTRS)

    Anderson, William J.

    1986-01-01

    Hostile environments such as the hard vacuum of space, and exposure to water or caustic fluids have fostered the development of devices which allow mechanical rotary feed throughs with positive sealing without the use of conventional dynamic seals. One such device is an electromagnetic coupling which transfers motion across a hermetic seal by means of a rotating magnetic field. Static pull-out torque and dynamic heat build-up and pull-out torque tests of a synchronous reluctance homopolar coupling are reported herein. Coupling efficiencies are estimated for a range of speeds and torques.

  9. Electromagnetic properties of the early universe

    SciTech Connect

    Takahashi, Keitaro; Ichiki, Kiyotomo; Sugiyama, Naoshi

    2008-06-15

    Detailed physical processes of magnetic field generation from density fluctuations in the prerecombination era are studied. Solving Maxwell equations and the generalized Ohm's law, the evolutions of the net charge density, the electric current, and the electromagnetic field are solved. Unlike most of the previous works, we treat electrons and photons as separate components under the assumption of tight coupling. We find that generation of the magnetic field due to density fluctuations takes place only from the second order of both perturbation theory and the tight coupling approximation.

  10. Giant field enhancement in electromagnetic Helmholtz nanoantenna

    NASA Astrophysics Data System (ADS)

    Chevalier, Paul; Bouchon, Patrick; Greffet, Jean-Jacques; Pelouard, Jean-Luc; Haïdar, Riad; Pardo, Fabrice

    2014-11-01

    Inspired by the acoustic Helmholtz resonator, we propose a slit-box electromagnetic nanoantenna able to concentrate the energy of an incident beam into surfaces a thousand times smaller than with a classical lens. This design produces a giant electric field enhancement throughout the slit. The intensity enhancement reaches 104 in the visible range up to 108 in the THz range even with focused beams, thanks to an omnidirectional reception. These properties could target applications requiring extreme light concentration, such as surface-enhanced infrared absorption, nonlinear optics, and biophotonics.

  11. On electromagnetic field problems in inhomogeneous media

    NASA Technical Reports Server (NTRS)

    Mohsen, A.

    1973-01-01

    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.

  12. Electromagnetic imaging of dynamic brain activity

    SciTech Connect

    Mosher, J.; Leahy, R.; Lewis, P.; Lewine, J.; George, J.; Singh, M.

    1991-12-31

    Neural activity in the brain produces weak dynamic electromagnetic fields that can be measured by an array of sensors. Using a spatio-temporal modeling framework, we have developed a new approach to localization of multiple neural sources. This approach is based on the MUSIC algorithm originally developed for estimating the direction of arrival of signals impinging on a sensor array. We present applications of this technique to magnetic field measurements of a phantom and of a human evoked somatosensory response. The results of the somatosensory localization are mapped onto the brain anatomy obtained from magnetic resonance images.

  13. Precision electromagnetic calorimetry with liquid krypton

    SciTech Connect

    Takai, H.

    1995-02-01

    Test beam results of a liquid krypton electromagnetic calorimeter with projective accordion electrode are presented. The electrode design includes a fine segmentation section to enhance the {pi}{sup 0} rejection and pointing. The test was carried out at the H4 beam line at the CERN SPS with electron beams of energy from 20 to 200 GeV. Preliminary results of energy resolution, linearity, {mu} response are presented. The author also presents the dependence of the energy resolution on the amount of inactive material in front of the calorimeter.

  14. Electromagnetic sensors for general lightning application

    NASA Technical Reports Server (NTRS)

    Baum, C. E.; Breen, E. L.; Onell, J. P.; Moore, C. B.; Sower, G. D.

    1980-01-01

    Electromagnetic sensors for general lightning applications in measuring environment are discussed as well as system response to the environment. This includes electric and magnetic fields, surface current and charge densities, and currents on conductors. Many EMP sensors are directly applicable to lightning measurements, but there are some special cases of lightning measurements involving direct strikes which require special design considerations for the sensors. The sensors and instrumentation used by NMIMT in collecting data on lightning at South Baldy peak in central New Mexico during the 1978 and 1979 lightning seasons are also discussed. The Langmuir Laboratory facilities and details of the underground shielded instrumentation room and recording equipment are presented.

  15. A multichannel electromagnetic flowmeter telemetry system.

    NASA Technical Reports Server (NTRS)

    Fryer, T. B.; Sandler, H.; Doane, D. H.

    1972-01-01

    An eight-channel biomedical telemetry system provides four channels of blood flow measurements in addition to blood-pressure and EKG data. Emphasis is placed on the amplifiers and signal conditioning circuitry required for interfacing of the electromagnetic flow transducers with the transmission and modulation subsystems. The large number of data channels permits measurement of flow distribution as well as total cardiac output. The batteries and electronics for four channels (blood flow) weigh about 500 g and have a volume of 250 cu cm.

  16. ELECTROMAGNETIC APPARATUS FOR MOVING A ROD

    DOEpatents

    Young, J.N.

    1958-04-22

    An electromagnetic apparatus for moving a rod-like member in small steps in either direction is described. The invention has particular application in the reactor field where the reactor control rods must be moved only a small distance and where the use of mechanical couplings is impractical due to the high- pressure seals required. A neutron-absorbing rod is mounted in a housing with gripping uaits that engage the rod, and coils for magnetizing the gripping units to make them grip, shift, and release the rod are located outside the housing.

  17. Electromagnetic radiation under explicit symmetry breaking.

    PubMed

    Sinha, Dhiraj; Amaratunga, Gehan A J

    2015-04-10

    We report our observation that radiation from a system of accelerating charges is possible only when there is explicit breaking of symmetry in the electric field in space within the spatial configuration of the radiating system. Under symmetry breaking, current within an enclosed area around the radiating structure is not conserved at a certain instant of time resulting in radiation in free space. Electromagnetic radiation from dielectric and piezoelectric material based resonators are discussed in this context. Finally, it is argued that symmetry of a resonator of any form can be explicitly broken to create a radiating antenna. PMID:25910163

  18. Electromagnetic simulations of coaxial type HOM coupler

    SciTech Connect

    Genfa Wu; Haipeng Wang; Robert Rimmer; Charles Reece

    2005-07-10

    DESY-type coaxial high order mode (HOM) coupler was used in many superconducting cavities. The electric probe tip is located at the maximum B-field inside the coupler can. For continuous wave (CW) high current application, the heating of this tip can be severe to degrade the cavity performance. Electromagnetic (EM) simulation was done to estimate the tip heating. The geometric remedies and detuning effect were discussed. The effect to HOM external quality factor (Qext) was also estimated due to these remedies. The HOM probe tip heating power was provided for CEBAF 12-GeV cavities and AES injector cavities.

  19. Electromagnetic studies of nucleon and nuclear structure

    SciTech Connect

    Heisenberg, J.H.; Calarco, J.R.; Hersman, F.W.; Dawson, J.F.

    1993-06-01

    Important objectives of the group are the study of subatomic structure through experimental measurements and the interpretation of the data through modeling. The common theme that unifies the studies of strong interactions and hadronic systems is the effort to determine the electromagnetic response as completely as possible. The general approach is coincidence detection of exclusive final states and determination of the dependence on the spin variables using polarized beams and targets and outgoing nucleon polarimetry. Direct reaction and giant resonance studies of electron quasi-elastic scattering on {sup 12}C and {sup 16}O are reported, as well as work on nuclear structure models and instrumentation development.

  20. Electromagnetic imaging of dynamic brain activity

    SciTech Connect

    Mosher, J.; Leahy, R. . Dept. of Electrical Engineering); Lewis, P.; Lewine, J.; George, J. ); Singh, M. . Dept. of Radiology)

    1991-01-01

    Neural activity in the brain produces weak dynamic electromagnetic fields that can be measured by an array of sensors. Using a spatio-temporal modeling framework, we have developed a new approach to localization of multiple neural sources. This approach is based on the MUSIC algorithm originally developed for estimating the direction of arrival of signals impinging on a sensor array. We present applications of this technique to magnetic field measurements of a phantom and of a human evoked somatosensory response. The results of the somatosensory localization are mapped onto the brain anatomy obtained from magnetic resonance images.

  1. Performances of the AMS-02 Electromagnetic Calorimeter

    NASA Astrophysics Data System (ADS)

    Adloff, C.; Coignet, G.; Girard, L.; Goy, C.; Kossakowski, R.; Lees-Rosier, S.; Pochon, J.; Vialle, J. P.; Cervelli, F.; di Falco, S.; Galeotti, S.; Incagli, M.; Pedreschi, E.; Spinella, F.; Venanzoni, G.; Falchini, E.; Maestro, P.; Marrocchesi, P. S.; Paoletti, R.; Pilo, F.; Turini, N.; Valle, G.; Bolmont, J.; Jacholkowska, A.; Piron, F.; Sapinski, M.; Chen, G.; Chen, G.; Chen, H. S.; Lu, Y.; Yang, C.

    2004-07-01

    A 3D imaging electromagnetic calorimeter (ECAL) made of scintillating fibers embedded in lead has been developed for the AMS-02 experiment to be installed on the International Space Station. A full scale ECAL prototype, partially instrumented, was tested in July 2002 in a beam at CERN. Several million events were recorded using muon, electron, proton, and antiproton beams, from which the ECAL behavior was determined. Results on the measurement of the ECAL parameters and performances are presented : radiation length, linearity, energy and angular resolutions, e/p separation.

  2. Electromagnetically induced grating with maximal atomic coherence

    SciTech Connect

    Carvalho, Silvania A.; Araujo, Luis E. E. de

    2011-10-15

    We describe theoretically an atomic diffraction grating that combines an electromagnetically induced grating with a coherence grating in a double-{Lambda} atomic system. With the atom in a condition of maximal coherence between its lower levels, the combined gratings simultaneously diffract both the incident probe beam as well as the signal beam generated through four-wave mixing. A special feature of the atomic grating is that it will diffract any beam resonantly tuned to any excited state of the atom accessible by a dipole transition from its ground state.

  3. Electromagnetic modulation of monochromatic neutrino beams

    NASA Astrophysics Data System (ADS)

    Barabanov, A. L.; Titov, O. A.

    2016-02-01

    We discuss the possibility to produce a modulated monochromatic neutrino beam. Monochromatic neutrinos can be obtained in electron capture by nuclei of atoms or ions. Hydrogen-like ions are of particular interest. It is shown that monochromatic neutrino beam from such hydrogen-like ions with nuclei of non-zero spin can be modulated because of different probabilities of electron capture from hyperfine states. Modulation arises by means of inducing of electromagnetic transitions between the hyperfine states. Requirements for the hydrogen-like ions with necessary properties are discussed. A list of the appropriate nuclei for such ions is presented.

  4. Electromagnetic magic: The relativistically rotating disk

    SciTech Connect

    Lynden-Bell, D.

    2004-11-15

    A closed form analytic solution is found for the electromagnetic field of the charged uniformly rotating conducting disk for all values of the tip speed v up to c. For v=c it becomes the magic field of the Kerr-Newman black hole with G set to zero. The field energy, field angular momentum, and gyromagnetic ratio are calculated and compared with those of the electron. A new mathematical expression that sums products of three Legendre functions, each of a different argument, is demonstrated.

  5. Electromagnetic Radiation under Explicit Symmetry Breaking

    NASA Astrophysics Data System (ADS)

    Sinha, Dhiraj; Amaratunga, Gehan A. J.

    2015-04-01

    We report our observation that radiation from a system of accelerating charges is possible only when there is explicit breaking of symmetry in the electric field in space within the spatial configuration of the radiating system. Under symmetry breaking, current within an enclosed area around the radiating structure is not conserved at a certain instant of time resulting in radiation in free space. Electromagnetic radiation from dielectric and piezoelectric material based resonators are discussed in this context. Finally, it is argued that symmetry of a resonator of any form can be explicitly broken to create a radiating antenna.

  6. Electromagnetically induced transparency with noisy lasers

    SciTech Connect

    Xiao Yanhong; Wang Tun; Baryakhtar, Maria; Jiang Liang; Lukin, Mikhail D.; Van Camp, Mackenzie; Crescimanno, Michael; Hohensee, Michael; Walsworth, Ronald L.; Phillips, David F.; Yelin, Susanne F.

    2009-10-15

    We demonstrate and characterize two coherent phenomena that can mitigate the effects of laser phase noise for electromagnetically induced transparency (EIT): a laser-power-broadening-resistant resonance in the transmitted intensity cross correlation between EIT optical fields, and a resonant suppression of the conversion of laser phase noise to intensity noise when one-photon noise dominates over two-photon-detuning noise. Our experimental observations are in good agreement with both an intuitive physical picture and numerical calculations. The results have wide-ranging applications to spectroscopy, atomic clocks, and magnetometers.

  7. Electromagnetic navigation bronchoscopy: A descriptive analysis

    PubMed Central

    Leong, Steven; Ju, Hong; Marshall, Henry; Bowman, Rayleen; Yang, Ian; Ree, Ann-Maree; Saxon, Cathy

    2012-01-01

    Electromagnetic navigation bronchoscopy (ENB) is an exciting new bronchoscopic technique that promises accurate navigation to peripheral pulmonary target lesions, using technology similar to a car global positioning system (GPS) unit. Potential uses for ENB include biopsy of peripheral lung lesions, pleural dye marking of nodules for surgical wedge resection, placement of fiducial markers for stereotactic radiotherapy, and therapeutic insertion of brachytherapy catheters into malignant tissue. This article will describe the ENB procedure, review the published literature, compare ENB to existing biopsy techniques, and outline the challenges for widespread implementation of this new technology. PMID:22833823

  8. Unstable Electromagnetic Modes in Strongly Magnetized Plasmas

    NASA Astrophysics Data System (ADS)

    Son, S.; Moon, Sung Joon

    2013-09-01

    A theory for instability in the long-time limit, arising from the electron gyro-motion in strongly magnetized plasmas, is presented. The analysis of the electron motion in the presence of a strong magnetic field leads to a theoretical framework similar to that of the Landau damping. Various electromagnetic modes are predicted to be possibly unstable, and the regime where the radiation from this instability would stand out, compared to the incoherent electron-cyclotron radiation, is identified. This instability would be relevant to the inertial confinement fusion and the gamma ray burst.

  9. Electromagnetic Propagation Prediction Inside Aircraft Cabins

    NASA Technical Reports Server (NTRS)

    Hankins, Genevieve; Vahala, Linda; Beggs, John H.

    2004-01-01

    Electromagnetic propagation models for signal strength prediction within aircraft cabins are essential for evaluating and designing a wireless communication system to be implemented onboard aircraft. A model was developed using Wireless Valley's SitePlanner; which is commercial grade software intended for predictions within office buildings. The performance of the model was evaluated through a comparison with test data measurements taken on several aircraft. The comparison concluded that the model can accurately predict power propagation within the cabin. This model can enhance researchers understanding of power propagation within aircraft cabins and will aid in future research.

  10. Electromagnetic Detection of a Perfect Invisibility Cloak

    SciTech Connect

    Zhang Baile; Wu, Bae-Ian

    2009-12-11

    A perfect invisibility cloak is commonly believed to be undetectable from electromagnetic (EM) detection because it is equivalent to a curved but empty EM space created from coordinate transformation. Based on the intrinsic asymmetry of coordinate transformation applied to motions of photons and charges, we propose a method to detect this curved EM space by shooting a fast-moving charged particle through it. A broadband radiation generated in this process makes a cloak visible. Our method is the only known EM mechanism so far to detect an ideal perfect cloak (curved EM space) within its working band.

  11. Inelastic deformation of conductive bodies in electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Altenbach, Holm; Morachkovsky, Oleg; Naumenko, Konstantin; Lavinsky, Denis

    2015-12-01

    Inelastic deformation of conductive bodies under the action of electromagnetic fields is analyzed. Governing equations for non-stationary electromagnetic field propagation and elastic-plastic deformation are presented. The variational principle of minimum of the total energy is applied to formulate the numerical solution procedure by the finite element method. With the proposed method, distributions of vector characteristics of the electromagnetic field and tensor characteristics of the deformation process are illustrated for the inductor-workpiece system within a realistic electromagnetic forming process.

  12. Thermodynamic restrictions on the constitutive equations of electromagnetic theory

    NASA Technical Reports Server (NTRS)

    Coleman, B. D.; Dill, E. H.

    1971-01-01

    Thermodynamics second law restrictions on constitutive equations of electromagnetic theory for nonlinear materials with long-range gradually fading memory, considering dissipation principle consequences

  13. An electromagnetic theory of turbulence driven poloidal rotation

    SciTech Connect

    McDevitt, C. J.; Guercan, Oe. D.

    2012-10-15

    An electromagnetic theory of turbulence driven poloidal rotation is developed with particular emphasis on understanding poloidal rotation in finite-{beta} plasmas. A relation linking the flux of polarization charge to the divergence of the total turbulent stress is derived for electromagnetic gyrokinetic modes. This relation is subsequently utilized to derive a constraint on the net electromagnetic turbulent stress exerted on the poloidal flow. Various limiting cases of this constraint are considered, where it is found that electromagnetic contributions to the turbulent stress may either enhance or reduce the net turbulent stress depending upon the branch of turbulence excited.

  14. Sensing network for electromagnetic fields generated by seismic activities

    NASA Astrophysics Data System (ADS)

    Gershenzon, Naum I.; Bambakidis, Gust; Ternovskiy, Igor V.

    2014-06-01

    The sensors network is becoming prolific and play now increasingly more important role in acquiring and processing information. Cyber-Physical Systems are focusing on investigation of integrated systems that includes sensing, networking, and computations. The physics of the seismic measurement and electromagnetic field measurement requires special consideration how to design electromagnetic field measurement networks for both research and detection earthquakes and explosions along with the seismic measurement networks. In addition, the electromagnetic sensor network itself could be designed and deployed, as a research tool with great deal of flexibility, the placement of the measuring nodes must be design based on systematic analysis of the seismic-electromagnetic interaction. In this article, we review the observations of the co-seismic electromagnetic field generated by earthquakes and man-made sources such as vibrations and explosions. The theoretical investigation allows the distribution of sensor nodes to be optimized and could be used to support existing geological networks. The placement of sensor nodes have to be determined based on physics of electromagnetic field distribution above the ground level. The results of theoretical investigations of seismo-electromagnetic phenomena are considered in Section I. First, we compare the relative contribution of various types of mechano-electromagnetic mechanisms and then analyze in detail the calculation of electromagnetic fields generated by piezomagnetic and electrokinetic effects.

  15. A class of non-null toroidal electromagnetic fields and its relation to the model of electromagnetic knots

    NASA Astrophysics Data System (ADS)

    Arrays, Manuel; Trueba, Jos L.

    2015-01-01

    An electromagnetic knot is an electromagnetic field in vacuum in which the magnetic lines and the electric lines coincide with the level curves of a pair of complex scalar fields ? and ? (see equations (A.1), (A.2)). When electromagnetism is expressed in terms of electromagnetic knots, it includes mechanisms for the topological quantization of the electromagnetic helicity, the electric charge, the electromagnetic energy inside a cavity and the magnetic flux through a superconducting ring. In the case of electromagnetic helicity, its topological quantization depends on the linking number of the field lines, both electric and magnetic. Consequently, to find solutions of the electromagnetic knot equations with nontrivial topology of the field lines has important physical consequences. We study a new class of solutions of Maxwell's equations in vacuum Arrays and Trueba (2011 arXiv:1106.1122) obtained from complex scalar fields that can be interpreted as maps {{S}3}\\to {{S}2}, in which the topology of the field lines is that of the whole torus-knot set. Thus this class of solutions is built as electromagnetic knots at initial time. We study some properties of those fields and consider if detection based on the energy and momentum observables is possible.

  16. Electromagnetic mixing laws: A supersymmetric approach

    SciTech Connect

    Niez, J.J.

    2010-02-15

    In this article we address the old problem of finding the effective dielectric constant of materials described either by a local random dielectric constant, or by a set of non-overlapping spherical inclusions randomly dispersed in a host. We use a unified theoretical framework, such that all the most important Electromagnetic Mixing Laws (EML) can be recovered as the first iterative step of a family of results, thus opening the way to future improvements through the refinements of the approximation schemes. When the material is described by a set of immersed inclusions characterized by their spatial correlation functions, we exhibit an EML which, being featured by a minimal approximation scheme, does not come from the multiple scattering paradigm. It is made of a pure Hori-Yonezawa formula, corrected by a power series of the inclusion density. The coefficients of the latter, which are given as sums of standard diagrams, are recast into electromagnetic quantities which calculation is amenable numerically thanks to codes available on the web. The methods used and developed in this work are generic and can be used in a large variety of areas ranging from mechanics to thermodynamics.

  17. MEMS electromagnetic energy harvesters with multiple resonances

    NASA Astrophysics Data System (ADS)

    Nelatury, Sudarshan R.; Gray, Robert

    2014-06-01

    There is going on a flurry of research activity in the development of effcient energy harvesters from all branches of energy conversion. The need for developing self-powered wireless sensors and actuators to be employed in unmanned combat vehicles also seems to grow steadily. These vehicles are inducted into perilous war zones for silent watch missions. Energy management is sometimes carried out using misson-aware energy expenditure strategies. Also, when there is a requirement for constant monitoring of events, the sensors and the subsystems of combat vehicles require energy harvesters that can operate over a discrete set of spot frequencies. This paper attempts to review some of the recent techniques and the energy harvesting devices based on electromagnetic and electromechanical principles. In particular, we shall discuss the design and performance of a MEMS-harvester that exhibits multiple resonances. Frequency response of a simulated electromagnetic harvester is plotted. It has three dominant peaks at three different resonant frequencies. Variation in the load power in the normalized units as a function of load is found, which determines the matched load resistance.

  18. The refractive index of reciprocal electromagnetic media

    NASA Astrophysics Data System (ADS)

    McCall, Martin W.; Kinsler, Paul; Topf, Renè D. M.

    2016-04-01

    We study the electromagnetics of media described by identical inhomogeneous relative dielectric and magnetic tensors, {\\boldsymbol{ε }}={\\boldsymbol{μ }}. Such media occur generically as spatial transformation media, i.e. electromagnetic media that are defined by a deformation of space. We show that such media are completely described by a refractive index n({r},\\hat{{s}}) that depends on position {r} and direction \\hat{{s}}, but is independent of polarization. The phase surface is always ellipsoidal, and n({r},\\hat{{s}}) is therefore represented by the radius vector to the surface of the ellipsoid. We apply our method to calculate the angular dependence of the refractive index in the well-studied cylindrical cloak and to a new kind of structurally chiral medium induced by a twist deformation. By way of a simple example we also show that media for which {\\boldsymbol{ε }}={\\boldsymbol{μ }} do not in general preserve the impedance properties of vacuum. The implications of this somewhat surprising conclusion for the field of transformation optics are discussed.

  19. p-form electromagnetism on discrete spacetimes

    NASA Astrophysics Data System (ADS)

    Wise, Derek K.

    2006-09-01

    We investigate p-form electromagnetism—with the Maxwell and Kalb Ramond fields as lowest-order cases—on discrete spacetimes, including not only the regular lattices commonly used in lattice gauge theory, but also more general examples. After constructing a maximally general model of discrete spacetime suitable for our purpose—a chain complex equipped with an inner product on (p + 1)-cochains—we study both the classical and quantum versions of the theory, with either {\\bb R} or U(1) as gauge group. We find results—such as a 'p-form Bohm Aharonov effect'—that depend in interesting ways on the cohomology of spacetime. We quantize the theory via the Euclidean path integral formalism, where the natural kernels in the U(1) theory are not Gaussians but theta functions. As a special case of the general theory, we show that p-form electromagnetism in p + 1 dimensions has an exact solution which reduces when p = 1 to the Abelian case of 2D Yang Mills theory as studied by Migdal and Witten. Our main result describes p-form electromagnetism as a 'chain field theory'—a theory analogous to a topological quantum field theory, but with chain complexes replacing manifolds. This makes precise a notion of time evolution in the context of discrete spacetimes of arbitrary topology. A somewhat less technical, more expository version of this material appeared as gr-qc/0510033 [38].

  20. The Coupling of Electromagnetic Power to Plasmas

    SciTech Connect

    Koch, R

    2004-03-15

    This lecture complements the three previous lectures{sup 1,2,3} on waves by addressing, on the basis of elementary and intuitive treatment, the process of coupling of electromagnetic power to plasma. Coupling is here meant in a broad sense. It consists of four different steps. (i) The first one is the coupling of vacuum electromagnetic power to plasma waves. An elementary antenna coupling theory is given. The state of the art in coupling models and status of comparisons with experiments are briefly discussed. (ii) The second is the transfer of plasma wave energy to particle energy. The resonant processes leading to this transfer are described in a heuristic way. (iii) The third one is the build-up of fast particle populations. It will be outlined through a sketch of quasilinear diffusion for the simple case of Landau damping. (iv) The last step is the conversion of power through the resonant particle population to bulk plasma heating by collisions, which will be briefly addressed.

  1. Electromagnetic excitation of the Delta(1232) resonance

    SciTech Connect

    V. Pascalutsa; M. Vanderhaeghen; Shin Nan Yang

    2006-09-05

    We review the description of the lowest-energy nucleon excitation--the Delta(1232)-resonance. Much of the recent effort has been focused on the precision measurements of the nucleon to Delta transition by means of electromagnetic probes. We review the results of those measurements and confront them with the state-of-the-art calculations based on chiral effective-field theories (EFT), lattice QCD, and QCD-inspired models. Some of the theoretical approaches are reviewed in detail. In particular, we describe the chiral EFT of QCD in the energy domain of the Delta-resonance, and its applications to the electromagnetic nucleon-to-Delta transition (gamma N Delta). We also describe the recent dynamical and unitary-isobar models of pion electroproduction which are extensively used in the extraction of the gamma* N Delta form factors from experiment. Furthermore, we discuss the link of the gamma* N Delta form factors to generalized parton distributions (GPDs), as well as the predictions of perturbative QCD for these transition form factors. The present status of understanding the Delta-resonance properties and the nature of its excitation is summarized.

  2. Electromagnetic resonant modes of dielectric sphere bilayers

    NASA Astrophysics Data System (ADS)

    Andueza, A.; Pérez-Conde, J.; Sevilla, J.

    2015-05-01

    Sphere bilayers have been proposed as promising structures for electromagnetic management in photonic crystal devices. These arrangements are made of two intertwined subsets of spheres of different size and refractive index, one subset filling the interstitial sites of the other. We present a systematic study of the electromagnetic resonant modes of the bilayers, in comparison with those of the constituent subsets of spheres. Three samples were built with glass and Teflon spheres and their transmission spectra measured in the microwave range (10-25 GHz). Simulations with finite integration time-domain method are in good agreement with experiments. Results show that the bilayer presents the same resonances as one of the subsets but modified by the presence of the other in its resonant frequencies and in the electric field distributions. As this distortion is not very large, the number of resonances in a selected spectral region is determined by the dominant subset. The degree of freedom that offers the bilayer could be useful to fine tune the resonances of the structure for different applications. A map of modes useful to guide this design is also presented. Scale invariance of Maxwell equations allows the translation of these results in the microwave range to the visible region; hence, some possible applications are discussed in this framework.

  3. Principles of electromagnetic waves in metasurfaces

    NASA Astrophysics Data System (ADS)

    Luo, XianGang

    2015-09-01

    Metasurfaces are artificially structured thin films with unusual properties on demand. Different from metamaterials, the metasurfaces change the electromagnetic waves mainly by exploiting the boundary conditions, rather than the constitutive parameters in three dimensional (3D) spaces. Despite the intrinsic similarities in the operational principles of metasurfaces, there is not a universal theory available for the understanding and design of these devices. In this article, we propose the concept of metasurface waves (M-waves) and provide a general theory to describe the principles of such waves. Most importantly, it is shown that the M-waves share some fundamental properties such as extremely short wavelength, abrupt phase change and strong chromatic dispersion, which making them different from traditional bulk waves. We show that these properties can enable many important applications such as subwavelength imaging and lithography, planar optical devices, broadband anti-reflection, absorption and polarization conversion. Our results demonstrated unambiguously that traditional laws of diffraction, refraction, reflection and absorption can be overcome by using the novel properties of M-waves. The theory provided here may pave the way for the design of new electromagnetic devices and further improvement of metasurfaces.

  4. INNOVATIVE ELECTROMAGNETIC SENSORS FOR PIPELINE CRAWLERS

    SciTech Connect

    J. Bruce Nestleroth

    2004-05-01

    Internal inspection of pipelines is an important tool for ensuring safe and reliable delivery of fossil energy products. However, not all pipelines can be inspected with current systems that move inside the pipeline propelled by the product flow. Inspection platforms that crawl slowly inside a pipeline are being developed to maneuver past the physical barriers that limit inspection. Battelle is building innovative electromagnetic sensors for pipeline crawlers. The various sensor types will assess a wide range of pipeline anomalies including corrosion, mechanical damage, cracking and seam weld defects. An implementation of two electromagnetic sensors were designed and tested. A pulsed eddy current system that uses sensors to measure the decay of induced eddy currents to establish the wall thickness has excellent potential. The results of experiments are comparable with magnetic flux leakage detecting 10% metal loss steps following a monotonic increase in signal strength. A rotating permanent remote field eddy current exciter was designed and built to produce strong signal levels at the receiver and reduce power consumption. Midway through the development of each technology, both sensor systems have produced results that warrant further development.

  5. Nanowire heating by optical electromagnetic irradiation.

    PubMed

    Roder, Paden B; Pauzauskie, Peter J; Davis, E James

    2012-11-20

    The dissipative absorption of electromagnetic energy by 1D nanoscale structures at optical frequencies is applicable to several important phenomena, including biomedical photothermal theranostics, nanoscale photovoltaic materials, atmospheric aerosols, and integrated photonic devices. Closed-form analytical calculations are presented for the temperature rise within infinite circular cylinders with nanometer-scale diameters (nanowires) that are irradiated at right angles by a continuous-wave laser source polarized along the nanowire's axis. Solutions for the heat source are compared to both numerical finite-difference time domain (FDTD) simulations and well-known Mie scattering cross sections for infinite cylinders. The analysis predicts that the maximum temperature increase is affected not only by the cylinder's composition and porosity but also by morphology-dependent resonances (MDRs) that lead to significant spikes in the local temperature at particular diameters. Furthermore, silicon nanowires with high thermal conductivities are observed to exhibit extremely uniform internal temperatures during electromagnetic heating to 1 part in 10(6), including cases where there are substantial fluctuations of the internal electric-field source term that generates the Joule heating. For a highly absorbing material such as carbon, much higher temperatures are predicted, the internal temperature distribution is nonuniform, and MDRs are not encountered. PMID:23061375

  6. NASA GRC High Power Electromagnetic Thruster Program

    NASA Astrophysics Data System (ADS)

    Lapointe, Michael R.; Pencil, Eric J.

    2004-02-01

    Interest in high power electromagnetic propulsion has been revived to support a variety of future space missions, such as platform maneuvering in low earth orbit, cost-effective cargo transport to lunar and Mars bases, asteroid and outer planet sample return, deep space robotic exploration, and piloted missions to Mars and the outer planets. Magnetoplasmadynamic (MPD) thrusters have demonstrated, at the laboratory level, the capacity to process megawatts of electrical power while providing higher thrust densities than current electric propulsion systems. The ability to generate higher thrust densities permits a reduction in the number of thrusters required to perform a given mission and alleviates the system complexity associated with multiple thruster arrays. The specific impulse of an MPD thruster can be optimized to meet given mission requirements, from a few thousand seconds with heavier gas propellants up to 10,000 seconds with hydrogen propellant. In support of NASA space science and human exploration strategic initiatives, Glenn Research Center is developing and testing pulsed, MW-class MPD thrusters as a prelude to long-duration high power thruster tests. The research effort includes numerical modeling of self-field and applied-field MPD thrusters and experimental testing of quasi-steady MW-class MPD thrusters in a high power pulsed thruster facility. This paper provides an overview of the GRC high power electromagnetic thruster program and the pulsed thruster test facility.

  7. Electromagnetic Basis of Metabolism and Heredity

    NASA Technical Reports Server (NTRS)

    Freund, Friedemann; Stolc, Viktor

    2016-01-01

    Living organisms control their cellular biological clocks to maintain functional oscillation of the redox cycle, also called the "metabolic cycle" or "respiratory cycle". Organization of cellular processes requires parallel processing on a synchronized time-base. These clocks coordinate the timing of all biochemical processes in the cell, including energy production, DNA replication, and RNA transcription. When this universal time keeping function is perturbed by exogenous induction of reactive oxygen species (ROS), the rate of metabolism changes. This causes oxidative stress, aging and mutations. Therefore, good temporal coordination of the redox cycle not only actively prevents chemical conflict between the reductive and oxidative partial reactions; it also maintains genome integrity and lifespan. Moreover, this universal biochemical rhythm can be disrupted by ROS induction in vivo. This in turn can be achieved by blocking the electron transport chain either endogenously or exogenously by various metabolites, e.g. hydrogen sulfide (H2S), highly diffusible drugs, and carbon monoxide (CO). Alternatively, the electron transport in vivo can be attenuated via a coherent or interfering transfer of energy from exogenous ultralow frequency (ULF) and extremely low frequency (ELF) electromagnetic (EM) fields, suggesting that-on Earth-such ambient fields are an omnipresent (and probably crucially important) factor for the time-setting basis of universal biochemical reactions in living cells. Our work demonstrated previously un-described evidence for quantum effects in biology by electromagnetic coupling below thermal noise at the universal electron transport chain (ETC) in vivo.

  8. Electromagnetic exploration of the oceanic mantle

    PubMed Central

    UTADA, Hisashi

    2015-01-01

    Electromagnetic exploration is a geophysical method for examining the Earth’s interior through observations of natural or artificial electromagnetic field fluctuations. The method has been in practice for more than 70 years, and 40 years ago it was first applied to ocean areas. During the past few decades, there has been noticeable progress in the methods of instrumentation, data acquisition (observation), data processing and inversion. Due to this progress, applications of this method to oceanic regions have revealed electrical features of the oceanic upper mantle down to depths of several hundred kilometers for different geologic and tectonic environments such as areas around mid-oceanic ridges, areas around hot-spot volcanoes, subduction zones, and normal ocean areas between mid-oceanic ridges and subduction zones. All these results estimate the distribution of the electrical conductivity in the oceanic mantle, which is key for understanding the dynamics and evolution of the Earth together with different physical properties obtained through other geophysical methods such as seismological techniques. PMID:26062736

  9. Nonradiating sources and the electromagnetic potentials

    NASA Astrophysics Data System (ADS)

    Marengo, Edwin A.; Ziolkowski, Richard W.

    2000-03-01

    We report a new description of monochromatic nonradiating current distributions that is based on the electromagnetic potentials. This enables us to address the question whether the potentials associated with a spatially localized nonradiating source can possess (or not) a measurable physical significance outside the source region. In particular, it is well known that, under electrodynamic conditions, the electromagnetic fields produced by a localized nonradiating source vanish everywhere outside the source's support. We address here the question of physical observability of the associated external potentials in connection with the Aharonov-Bohm effect. We consider, in particular, the Coulomb gauge, although a physically equivalent description holds in other gauges. It is shown that, under electrodynamic conditions, the potentials in the exterior of a localized nonradiating source necessarily vanish if one makes a particular gauge choice, i.e., they are there as unobservable as the corresponding nonradiating fields. This does not necessarily hold under static conditions in which one can have non-trivial potentials with physically observable effects in regions where the fields vanish, e.g., in the Aharonov-Bohm effect. We also report a previously unknown hierarchy of nonradiating current distributions, both spatially localized and non-localized ones.

  10. Accurate electromagnetic modeling of terahertz detectors

    NASA Technical Reports Server (NTRS)

    Focardi, Paolo; McGrath, William R.

    2004-01-01

    Twin slot antennas coupled to superconducting devices have been developed over the years as single pixel detectors in the terahertz (THz) frequency range for space-based and astronomy applications. Used either for mixing or direct detection, they have been object of several investigations, and are currently being developed for several missions funded or co-funded by NASA. Although they have shown promising performance in terms of noise and sensitivity, so far they have usually also shown a considerable disagreement in terms of performance between calculations and measurements, especially when considering center frequency and bandwidth. In this paper we present a thorough and accurate electromagnetic model of complete detector and we compare the results of calculations with measurements. Starting from a model of the embedding circuit, the effect of all the other elements in the detector in the coupled power have been analyzed. An extensive variety of measured and calculated data, as presented in this paper, demonstrates the effectiveness and reliability of the electromagnetic model at frequencies between 600 GHz and 2.5THz.

  11. A borehole-to-surface electromagnetic survey

    SciTech Connect

    Tseng, Hung-Wen; Becker, A.; Wilt, M.; Descz-Pan, M.

    1995-12-31

    We have assessed the feasibility of borehole to surface electromagnetic measurements for fluid injection monitoring. To do this we performed a vertical electromagnetic profiling (VEMP) experiment at the University of California Richmond Field Station where a saline water injection zone was created at a subsurface depth of 30 meters. The methodology used is quite similar to the conventional seismic (VSP) procedure for surface to borehole measurements. In our case however, the transmitter was located in a PVC cased borehole while the receivers were deployed on the surface. With a carefully designed system operating at 9.6 kHz we were able to make measurements accurate to 1 % in amplitude and 1 degree in phase. The data profiles at surface were centered on the injection well and extended for 60 m on either side of it. Measurements were made at 5 m intervals. Although the VEMP process is quite vulnerable to near surface conductivity anomalies we readily detected the flat tabular target zone which was about 3 m thick and covered an area of about 120 M{sup 2}.

  12. Electromagnetic instabilities in rotating magnetized viscous objects

    NASA Astrophysics Data System (ADS)

    Nekrasov, A. K.

    2009-12-01

    In this paper, we study electromagnetic streaming instabilities in the thermal viscous regions of rotating astrophysical objects, such as magnetized accretion discs, molecular clouds, their cores and elephant trunks. The results obtained can also be applied to any regions of interstellar medium, where different equilibrium velocities between charged species can arise. We consider a weakly ionized multicomponent plasma consisting of neutrals and magnetized electrons, ions and dust grains. We take into account the effect of perturbation of collisional frequencies as a result of the density perturbations of species. We obtain general expressions for the perturbed velocities of species involving the thermal pressure and viscosity when perturbations propagate perpendicular to the background magnetic field. The dispersion relation is derived and investigated for axisymmetric perturbations. New compressible instabilities generated as a result of different equilibrium velocities of different charged species are found in the cold and thermal limits either when the viscosity of neutrals can be neglected or when it is important. The viscosity of magnetized charged species is negligible for the perturbations considered that have wavelengths much larger than the Larmor radius of species. At the same time, the neutrals are shown to be immobile in electromagnetic perturbations when their viscosity is sufficiently large.

  13. Electromagnetic coilgun launcher for space applications

    SciTech Connect

    Turman, B.N.; Lipinski, R.J.

    1996-03-01

    A ground-based electrically-powered launcher could significantly reduce the complexity and cost of space launches for moderate-weight payloads. The electromagnetic launch complex could greatly reduce the amount of fuels handling, reduce the turn-around time between launches, allow more concurrence in launch preparation, reduce the manpower requirements for launch vehicle preparation and increase the reliability of launch by using more standardized vehicle preparations. The launch requires high acceleration, so the satellite package must be hardened. This paper presents results of a study to estimate the required launcher parameters, and estimate the cost of such a launch facility. This study is based on electromagnetic gun technology which is constrained to a coaxial geometry to take advantage of the efficiency of closely-coupled coils. The launcher energy and power requirements fall in the range of 40{endash}260 GJ and 20{endash}400 GW electric. Parametric evaluations have been conducted with a launcher length of 1{endash}2 km, exit velocity of 1{endash}6 km/s, and payloads to low earth orbit of 100{endash}1000 kg. {copyright} {ital 1996 American Institute of Physics.}

  14. Biomarkers of induced electromagnetic field and cancer.

    PubMed

    Behari, J; Paulraj, R

    2007-01-01

    The present article delineates the epidemiological and experimental studies of electromagnetic field which affects various tissues of human body. These affects lead to cell proliferation, which may lead to cancer formation. Certain biomarkers have been identified which are one way or the other responsible for tumor promotion or co-promotion. These are (i) melatonin, a hormone secreted by pineal gland, (ii) Ca2+, which is essential in the regulation of the resting membrane potential and in the sequence of events in synaptic excitation and neurotransmitter, release are affected by electromagnetic field, (iii) ornithine decarboxylase (ODC), a rate-limiting enzyme in the biosynthesis of polyamines, considered as a useful biological marker; over expression of ODC can cause cell transformation and enhancement of tumor promotion. (iv) protein kinase is an enzyme, which transfers phosphate groups from ATP to hydroxyl groups in the amino acid chains of acceptor proteins, and (v) Na+-K+ ATPase, which transports sodium and potassium ions across the membrane has a critical role in living cells. The various possible mechanisms depending upon non equilibrium thermodynamics, co-operativism, stochastic and resonance are discussed as possible models of signal transduction in cytosol, thereby controlling the transcription phenomena. Finally a mechanism comprising the extremely low frequency and radio frequency (RF)/microwave (MW) modulated field is compared. PMID:17249331

  15. Advanced electromagnetic methods for aerospace vehicles

    NASA Technical Reports Server (NTRS)

    Balanis, Constantine A.; Sun, Weimin; El-Sharawy, El-Budawy; Aberle, James T.; Birtcher, Craig R.; Peng, Jian; Tirkas, Panayiotis A.; Andrew, William V.; Kokotoff, David; Zavosh, Frank

    1993-01-01

    The Advanced Helicopter Electromagnetics (AHE) Industrial Associates Program has fruitfully completed its fourth year. Under the support of the AHE members and the joint effort of the research team, new and significant progress has been achieved in the year. Following the recommendations by the Advisory Task Force, the research effort is placed on more practical helicopter electromagnetic problems, such as HF antennas, composite materials, and antenna efficiencies. In this annual report, the main topics to be addressed include composite materials and antenna technology. The research work on each topic has been driven by the AHE consortium members' interests and needs. The remarkable achievements and progresses in each subject is reported respectively in individual sections of the report. The work in the area of composite materials includes: modeling of low conductivity composite materials by using Green's function approach; guidelines for composite material modeling by using the Green's function approach in the NEC code; development of 3-D volume mesh generator for modeling thick and volumetric dielectrics by using FD-TD method; modeling antenna elements mounted on a composite Comanche tail stabilizer; and antenna pattern control and efficiency estimate for a horn antenna loaded with composite dielectric materials.

  16. Advanced electromagnetic methods for aerospace vehicles

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    The Advanced Helicopter Electromagnetics (AHE) Industrial Associates Program has continuously progressed with its research effort focused on subjects identified and recommended by the Advisory Task Force of the program. The research activities in this reporting period have been steered toward practical helicopter electromagnetic problems, such as HF antenna problems and antenna efficiencies, recommended by the AHE members at the annual conference held at Arizona State University on 28-29 Oct. 1992 and the last biannual meeting held at the Boeing Helicopter on 19-20 May 1993. The main topics addressed include the following: Composite Materials and Antenna Technology. The research work on each topic is closely tied with the AHE Consortium members' interests. Significant progress in each subject is reported. Special attention in the area of Composite Materials has been given to the following: modeling of material discontinuity and their effects on towel-bar antenna patterns; guidelines for composite material modeling by using the Green's function approach in the NEC code; measurements of towel-bar antennas grounded with a partially material-coated plate; development of 3-D volume mesh generator for modeling thick and volumetric dielectrics by using FD-TD method; FDTD modeling of horn antennas with composite E-plane walls; and antenna efficiency analysis for a horn antenna loaded with composite dielectric materials.

  17. Extended-range electromagnetic induction concepts

    NASA Astrophysics Data System (ADS)

    Miller, Jonathan S.; Bassani, Chet; Schultz, Gregory

    2015-05-01

    Typically, electromagnetic sensors are applied using one of two modalities to detect buried or obscured targets: 1) lower frequency Electromagnetic Induction (EMI) sensors that enable detection of targets in the near-field; and 2) higher frequency wave propagation sensors, such as Forward Looking or Ground Penetrating Radar (FL/GPR) that enable detection of targets in the far-field. Each modality has advantages and limitations. EMI sensors enable deep penetration of overburden or structures that may obscure a target; however, sensitivity is typically limited to high conductivity targets (i.e., metals) due to the relatively low frequency of operation. Wave propagation sensors, such as GPR, enable detection of both conductive and non-conductive targets as a result of inherent dielectric contrast sensitivity; however, penetration into ground or structures is limited due to rapid attenuation of the propagating wave through lossy materials. In this paper, we present a concept for enhancing the target range capabilities of EMI sensors to extend sensitivity to lower conductivity targets. This concept incorporates an efficient transmitter driver design that extends the range of EMI operation into the High Frequency (HF) band while providing high power output. This ability to produce high frequency, high power output provides a sensor modality that bridges the gap between traditional EMI and wave propagating modalities. This High Frequency Transmitter (HFTX) concept could enable sensitivity to low conductivity targets (i.e., non-metals) while maintaining effective penetration through soil overburden or other materials that would typically impede GPR wave propagation.

  18. Plant Responses to High Frequency Electromagnetic Fields.

    PubMed

    Vian, Alain; Davies, Eric; Gendraud, Michel; Bonnet, Pierre

    2016-01-01

    High frequency nonionizing electromagnetic fields (HF-EMF) that are increasingly present in the environment constitute a genuine environmental stimulus able to evoke specific responses in plants that share many similarities with those observed after a stressful treatment. Plants constitute an outstanding model to study such interactions since their architecture (high surface area to volume ratio) optimizes their interaction with the environment. In the present review, after identifying the main exposure devices (transverse and gigahertz electromagnetic cells, wave guide, and mode stirred reverberating chamber) and general physics laws that govern EMF interactions with plants, we illustrate some of the observed responses after exposure to HF-EMF at the cellular, molecular, and whole plant scale. Indeed, numerous metabolic activities (reactive oxygen species metabolism, α- and β-amylase, Krebs cycle, pentose phosphate pathway, chlorophyll content, terpene emission, etc.) are modified, gene expression altered (calmodulin, calcium-dependent protein kinase, and proteinase inhibitor), and growth reduced (stem elongation and dry weight) after low power (i.e., nonthermal) HF-EMF exposure. These changes occur not only in the tissues directly exposed but also systemically in distant tissues. While the long-term impact of these metabolic changes remains largely unknown, we propose to consider nonionizing HF-EMF radiation as a noninjurious, genuine environmental factor that readily evokes changes in plant metabolism. PMID:26981524

  19. Standing Electromagnetic Waves in Superconducting Thin Films

    NASA Astrophysics Data System (ADS)

    Beeli, P.

    2001-03-01

    One of the signature properties of superconductivity is its zero frequency dissipationlessness. Under these conditions, the k-vector is purely imaginary and is determined by reciprocating the London penetration depth (λ_L). But at non-zero frequencies, superconductors dissipate energy. This means that λL is insufficient to account for surface resistance and that the presence of surface resistance means that the k-vector now includes a wavelength and is complex. This apparently adverse property of dissipation however, ushers in some interesting physics: dissipation means that the fields are characterized by a finite wavelength. A finite wavelength means that standing electromagnetic waves can occur in superconducting films. The periodicity of the resonant thicknesses (Δd) in otherwise identical superconducting films is a new length scale in superconductors and is given by Δd=-π\\verttildeλ\\vert^2/Im(tildeλ), where tildeλ is the complex electromagnetic penetration depth of the superconducting thin-film and Im is the imaginary operator. This resonant effect is most pronounced near the transition temperature and it is necessary to delineate its contribution in a host of enigmatic data that have been known for over 30 years including the quantum-size effect, Wyatt-Dayem effect, Carlson-Goldman mode, non-equilibrium superconductivity... [P. Beeli, J. Supercond., in press].

  20. Electromagnetic coilgun launcher for space applications

    NASA Astrophysics Data System (ADS)

    Turman, B. N.; Lipinski, R. J.

    1996-03-01

    A ground-based electrically-powered launcher could significantly reduce the complexity and cost of space launches for moderate-weight payloads. The electromagnetic launch complex could greatly reduce the amount of fuels handling, reduce the turn-around time between launches, allow more concurrence in launch preparation, reduce the manpower requirements for launch vehicle preparation and increase the reliability of launch by using more standardized vehicle preparations. The launch requires high acceleration, so the satellite package must be hardened. This paper presents results of a study to estimate the required launcher parameters, and estimate the cost of such a launch facility. This study is based on electromagnetic gun technology which is constrained to a coaxial geometry to take advantage of the efficiency of closely-coupled coils. The launcher energy and power requirements fall in the range of 40-260 GJ and 20-400 GW electric. Parametric evaluations have been conducted with a launcher length of 1-2 km, exit velocity of 1-6 km/s, and payloads to low earth orbit of 100-1000 kg.