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Results for “ELECTROMAGNETIC INTERACTIONS”

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

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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Suppression and enhancement of electromagnetic pulses from laser–target interactions by strong magnetic fields

Laser–target interactions generate intense electromagnetic pulses (EMPs) that can interfere with measurements and damage equipment. In this paper we show that applying a magnetic field to nanosecond pulse laser–target interactions decreases the magnitude of EMPs. We demonstrate this effect in two experiments with different geometries (spherical versus planar), laser intensities ( ∼10 13 versus ∼10 15 W/cm 2 ) and applied field strength (12 versus 0.1 T) that both observed suppression of EMPs in approximately the 1 GHz band (by factors of 0.65× and 0.32×, respectively). We then observe the opposite effect at high intensities with a picosecond pulse: for planar experiments with laser intensities of approximately 10 19 W/cm 2 and magnetic fields of 6–10 T, the magnitude of EMPs is increased by a factor of 1.75×. These results provide a benchmark for models of EMP generation, but suggest that magnetic fields are not a viable solution for mitigating EMPs in the high-intensity laser facilities where they are most damaging.

electromagnetic pulse↗
DOE OSTI2013

Enhanced nonlinear interaction of powerful electromagnetic waves with ionospheric plasma near the second electron gyroharmonic

Plasma experiments in which a powerful electromagnetic pump wave is transmitted into the ionosphere from the ground give access to a rich range of phenomena, including gyroharmonic effects when the pump frequency is near an harmonic of the ionospheric electron gyrofrequency. For pump frequencies close to the second gyroharmonic, experiments show a strong enhancement, as observed in radar scatter from pump-induced geomagnetic field-aligned density striations and optical emissions. This is in contrast to the case at the third harmonic and higher at which most of the effects are instead suppressed. We show theoretically that electrostatic oscillations can be localized in density inhomogeneities associated with small scale striations. The localized field is a mixture of the electron Bernstein and upper hybrid modes when the pump frequency is near the second gyroharmonic. The coupling of the modes is enabled by a symmetry feature of the linear electron Bernstein and upper hybrid dispersion properties that occur only near the second gyroharmonic. Electron acceleration inside the density inhomogeneities by localized azimuthal electrostatic oscillations is more efficient near the second gyroharmonic than at higher frequencies, consistent with the observed enhancements.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Nonlinear interaction of intense electromagnetic waves with a magnetoactive electron-positron-ion plasma

The nonlinear coupling between circularly polarized electromagnetic (CPEM) waves and acoustic-like waves in a magnetoactive electron-positron-ion (e-p-i) plasma is studied, taking into account the relativistic motion of electrons and positrons. The possibility of modulational instability and its growth rate as well as the envelope soliton formation and its characteristics in such plasmas are investigated. It is found that the growth rate of modulation instability increases in the case that ω{sub c}/ω<1 (ω{sub c} and ω are the electron gyrofrequency and the CPEM wave frequency, respectively) and decreases in the case that ω{sub c}/ω>1. It is also shown that in a magnetoactive e-p-i plasma, the width of bright soliton increases/decreases in case of (ω{sub c}/ω)<1/(ω{sub c}/ω)>1 by increasing the magnetic field strength.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

A Data Analysis Center for Electromagnetic and Hadronic Interaction

The GW Data Analysis Center (DAC) has made significant progress in its program to enhance and expand the partial-wave and multipole analyses of fundamental reactions, while maintaining and expanding each associated database. These efforts provide guidance to national and international experimental and theoretical efforts, and are an important link between theory and experiment. Our principal goals are focused on baryon and meson physics programs and related topics.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Work and energy for particles in electromagnetic field

Defining the energy and work for particles interacting with electromagnetic field (EMF) is an open problem, because—due to the gauge-freedom—there exist various non-equivalent possibilities. It is argued that a consistent definition can be provided via the Lorenz gauge. To this end, I work out a system of two electromagnetically coupled classical particles. One of them is much heavier and models the source of work. The definition of energy in the Lorenz gauge is causal and consistent, because it leads to an approximate conservation law due to which the work done by the heavy particle (source of work) can be defined either via the kinetic energy of the heavy particle, or via the full time-dependent energy (kinetic + potential in the Lorenz gauge) of the light particle.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Emergent spin electromagnetism induced by magnetization textures in the presence of spin-orbit interaction (invited)

Emergent electromagnetic field which couples to electron's spin in ferromagnetic metals is theoretically studied. Rashba spin-orbit interaction induces spin electromagnetic field which is in the linear order in gradient of magnetization texture. The Rashba-induced effective electric and magnetic fields satisfy in the absence of spin relaxation the Maxwell's equations as in the charge-based electromagnetism. When spin relaxation is taken into account besides spin dynamics, a monopole current emerges generating spin motive force via the Faraday's induction law. The monopole is expected to play an important role in spin-charge conversion and in the integration of spintronics into electronics.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Analysis of an Electromagnetic Wave with Circular Electron Beam Interaction in a Slow-Wave System of “Ribbed-Metal-Rod” Type

The interaction of an electromagnetic wave and external annular electron beam in a slow-wave system (SWS) of ribbed-metal-rod type was analyzed and expressions for the equivalent parameters of inductance and capacitance of the structure were found. A dispersion equation describing the excitation of axisymmetric electric waves in the SWS was derived in the impedance approximation. The dispersion characteristics and coupling coefficient have been modeled depending on the geometry of the rod and dielectric permittivity of the material filling the grooves in the SWS structure.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

Electromagnetic theory of the nuclear interaction. Application to the deuteron {sup 2}H

Bieler of the Rutherford laboratory imagined in 1924 a magnetic attraction equilibrating an electrostatic repulsion between the protons. Since the discovery of the neutron and the magnetic moments of the nucleons proving that the neutron contains electric charges, nobody, as far as I know, has tried to apply electromagnetism to the nuclear interaction. The electrostatic and magnetic interactions are completely neglected except for a mean Coulomb repulsion. As it is well known, there is an attraction between an electric charge and a neutral conductor. In the neutron, the positive charges are repelled and the negative charges attracted by a nearby proton. There is a net attraction explaining quantitatively the so-called strong force as it is shown in this paper. In the deuteron, the magnetic repulsion equilibrates the electrostatically induced neutron-proton attraction. The experimental value (- 2.2 MeV) is surrounded by - 1.6 MeV and - 2.5 MeV, depending on the calculation method. No arbitrary fitting parameter is used, only physical constants: it is a true ab initio calculation. The theoretical ratio between nuclear and chemical energies has been found to be (m{sub p}/m{sub e}{alpha}), proving that the usual assumption that the electromagnetic interaction is too feeble to predict the nuclear interaction is incorrect.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Recent N* results from photoproduction experiments at CLAS

The recent breakthroughs in the technology of polarised targets have enabled a new generation of meson photo-production experiments to be carried out. A measurement of a full set of polarisation observables off both polarised proton and neutron targets and in a large number of meson-production channels has come within sight. Such a measurement would very significantly reduce model-dependence in the analysis of the data and thus has the potential to resolve long-standing issues, such as the 'missing resonance' problem, and shed new light on the nucleon excitation spectrum. This has formed the motivation for the recent N* experimental programme of CLAS.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Porous material for protection from electromagnetic radiation

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.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2011

X-RAY SPECTROSCOPY OF AS1101 WITH CHANDRA, XMM-NEWTON, AND ROSAT: BANDPASS DEPENDENCE OF THE TEMPERATURE PROFILE AND SOFT EXCESS EMISSION

We present spatially resolved spectroscopy of the galaxy cluster AS1101, also known as Sersic 159-03, with Chandra, XMM-Newton, and ROSAT, and investigate the presence of soft X-ray excess emission above the contribution from the hot intracluster medium. In earlier papers we reported an extremely bright soft excess component that reached 100% of the thermal radiation in the R2 ROSAT band (0.2-0.4 keV), using the H I column density measurement by Dickey and Lockman. In this paper we use the newer Leiden-Argentine-Bonn survey measurements of the H I column density toward AS1101, significantly lower than the previous value, and show that the soft excess emission in AS1101 is now at the level of 10%-20% of the hot gas emission, in line with those of a large sample of clusters analyzed by Bonamente et al. in 2002. The ROSAT soft excess emission is detected regardless of calibration uncertainties between Chandra and XMM-Newton. This new analysis of AS1101 indicates that the 1/4 keV band emission is compatible with the presence of warm-hot intergalactic medium (WHIM) filaments connected to the cluster and extending outward into the intergalactic medium; the temperatures we find in this study are typically lower than those of the WHIM probed in other X-ray studies. We also show that the soft excess emission is compatible with a non-thermal origin as the inverse Compton scattering of relativistic electrons off the cosmic microwave background, with pressure less than 1% of the thermal electrons.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

In-medium Properties of {omega} and {eta}' Mesons in Elementary Reactions

We have investigated the in-medium properties of {omega} and eta prime mesons in photoproduction experiments using the Crystal Barrel(CB)/TAPS detector system at the ELSA accelerator facility in Bonn. Different methods to study the in-medium properties of the hadrons are discussed. The lineshape analysis of {omega}-mesons for two energy ranges shows limited sensitivity to in-medium modifications. Recent results on the in-medium width of the eta prime-meson, derived from transparency ratio measurements, are presented. The absorption of the eta prime-meson in nuclear matter is discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Inelastic processes and interference effects during the interaction of positronium with ultrashort electromagnetic pulses

The excitation, breakup, and reradiation during the interaction of a positronium atom with ultrashort electromagnetic pulses are considered. The probabilities of inelastic processes and reradiation spectra have been obtained. The interference between the amplitudes of the photon emission by the electron and positron is shown to contribute noticeably to the reradiation spectra. The developed approach is applicable for describing the interaction of positronium with ultrashort pulses of attosecond or shorter duration.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2011

SPECTRAL-TEMPORAL SIMULATIONS OF INTERNAL DISSIPATION MODELS OF GAMMA-RAY BURSTS

We present calculations of the time evolution of the prompt spectra of gamma-ray burst models involving generic internal dissipation regions, including internal shocks, either by itself or in the presence of an external photon source such as a photosphere. The method uses a newly developed time-dependent code involving synchrotron emission and absorption, inverse Compton scattering, and pair formation. The models reproduce the typically observed Band spectra and their generic time evolution, including the appearance of an extra keV-GeV component, whose delay in simple SSC models, however, is only partially able to explain the several seconds observed GeV delays. On the other hand, models involving both a photosphere and an internal dissipation region at a larger radius produce both an extra GeV component and time delays that are in the range of the observations.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

Ultra-High Gradient S-Band Linac for Laboratory And Industrial Applications

A strong demand for high gradient structures arises from the limited real estate available for linear accelerators. RadiaBeam Technologies is developing a Doubled Energy Compact Accelerator (DECA) structure: an S-band standing wave electron linac designed to operate at accelerating gradients of up to 50 MV/m. In this paper, we present the radio-frequency design of the DECA S-band accelerating structure, operating at 2.856 GHz in the {pi}-mode. The structure design is heavily influenced by NLC collaboration experience with ultra high gradient X-band structures; S-band, however, is chosen to take advantage of commonly available high power S-band klystrons.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Measurement of the {gamma}p{yields}{eta}p Reaction with the Crystal Ball Detector at the Mainz Microtron (MAMI-C)

The {gamma}p{yields}{eta}p reaction has been measured with the Crystal Ball and TAPS multiphoton spectrometers in the energy range from the production threshold to 1.4 GeV (1.49{<=}W{<=}1.87 GeV). Bremsstrahlung photons produced by the 1.5-GeV electron beam of the Mainz Microtron MAMI-C and momentum analyzed by the Glasgow Tagging Spectrometer were used for the {eta}-meson production. Our accumulation of 3.8x10{sup 6} {gamma}p{yields}{eta}p{yields}3{pi}{sup 0}p{yields}6{gamma}p events allows a detailed study of the reaction dynamics. The {gamma}p{yields}{eta}p differential cross sections were determined for 120 energy bins and the full range of the production angles. Our data show a dip near W = 1680 MeV in the total cross section related to a substantial dip in {eta} production at forward angles. The data are compared to predictions of previous SAID and MAID partial-wave analyses and to the latest SAID and MAID fits that included our data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Role of nonthermal electron on the dynamics of relativistic electromagnetic soliton in the interaction of laser-plasma

A system of nonlinear one-dimensional equations of the electron hydrodynamics with Maxwell's equations was developed to describe electromagnetic (EM) solitons in plasma with nonthermal electrons. Equation of vector potential was derived in relativistic regime by implementing the multiple scales technique, and their solitonic answers were introduced. The allowed regions for bright and dark electromagnetic solitons were discussed in detail. Roles of number density of nonthermal electrons, temperature of electrons, and frequency of fast participate of vector potential on the Sagdeev potential and properties of EM soliton were investigated. Results show that with increasing the number of nonthermal electrons, the amplitude of vector potential of bright solitons increases. By increasing the number of nonthermal electrons, dark EM solitons may be changed to bright solitons. Increasing the energy of nonthermal electrons leads to generation of high amplitude solitons.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2011

RCW 86: A TYPE Ia SUPERNOVA IN A WIND-BLOWN BUBBLE

We report results from a multi-wavelength analysis of the Galactic supernova remnant RCW 86, the proposed remnant of the supernova of 185 A.D. We show new infrared observations from the Spitzer Space Telescope and the Wide-Field Infrared Survey Explorer, where the entire shell is detected at 24 and 22 {mu}m. We fit the infrared flux ratios with models of collisionally heated ambient dust, finding post-shock gas densities in the non-radiative shocks of 2.4 and 2.0 cm{sup -3} in the southwest (SW) and northwest (NW) portions of the remnant, respectively. The Balmer-dominated shocks around the periphery of the shell, large amount of iron in the X-ray-emitting ejecta, and lack of a compact remnant support a Type Ia origin for this remnant. From hydrodynamic simulations, the observed characteristics of RCW 86 are successfully reproduced by an off-center explosion in a low-density cavity carved by the progenitor system. This would make RCW 86 the first known case of a Type Ia supernova in a wind-blown bubble. The fast shocks (>3000 km s{sup -1}) observed in the northeast are propagating in the low-density bubble, where the shock is just beginning to encounter the shell, while the slower shocks elsewhere have already encountered the bubble wall. The diffuse nature of the synchrotron emission in the SW and NW is due to electrons that were accelerated early in the lifetime of the remnant, when the shock was still in the bubble. Electrons in a bubble could produce gamma rays by inverse-Compton scattering. The wind-blown bubble scenario requires a single-degenerate progenitor, which should leave behind a companion star.

79 ASTRONOMY AND ASTROPHYSICS↗