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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 1,189 records · Page 66
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

The propagation of low-frequency whistler waves driven by ion beams in the magnetotail

The generation and propagation of low-frequency whistler waves excited by ion beams in the plasma sheet boundary layer are followed using standard ray tracing techniques and assuming a Harris-type neutral sheet magnetic field profiles. The density is chosen such that the total pressure remains constant. The wave energy is calculated along the wave path taking into account growth due to the ion beam while the wave is in the plasma sheet boundary layer as well as damping due to resonant interactions with the background plasma. The results show that the electromagnetic waves are guided toward the central plasma sheet by the plasma gradients but are damped out before reaching the neutral plane itself due to Cerenkov resonance with the hot central plasma sheet background ions. The amplitudes and final positions of the waves depend on the temperature of the background plasma, the ion beam drift speed, and the ion beam thermal speed.

Burinskaia, T.↗
NASA NTRS1995

The energy associated with MHD waves generation in the solar wind plasma

Gyrotropic symmetry is usually assumed in measurements of electron distribution functions in the heliosphere. This prevents the calculation of a net current perpendicular to the magnetic field lines. Previous theoretical results derived by one of the authors for a collisionless plasma with isotropic electrons in a strong magnetic field have shown that the excitation of MHD modes becomes possible when the external perpendicular current is non-zero. We consider then that any anisotropic electron population can be thought of as 'external', interacting with the remaining plasma through the self-consistent electromagnetic field. From this point of view any perpendicular current may be due to the anisotropic electrons, or to an external source like a stream, or to both. As perpendicular currents cannot be derived from the measured distribution functions, we resort to Ampere's law and experimental data of magnetic field fluctuations. The transfer of energy between MHD modes and external currents is then discussed.

delaTorre, A.↗
NASA NTRS2011

Processing Waveform-Based NDE

A computer implemented process for simultaneously measuring the velocity of terahertz electromagnetic radiation in a dielectric material sample without prior knowledge of the thickness of the sample and for measuring the thickness of a material sample using terahertz electromagnetic radiation in a material sample without prior knowledge of the velocity of the terahertz electromagnetic radiation in the sample is disclosed and claimed. Utilizing interactive software the process evaluates, in a plurality of locations, the sample for microstructural variations and for thickness variations and maps the microstructural and thickness variations by location. A thin sheet of dielectric material may be used on top of the sample to create a dielectric mismatch. The approximate focal point of the radiation source (transceiver) is initially determined for good measurements.

Roth, Donald J↗
DOE OSTI2015

Relativistic MHD simulations of collision-induced magnetic dissipation in Poynting-flux-dominated jets/outflows

The question of the energy composition of the jets/outflows in high-energy astrophysical systems, e.g. GRBs, AGNs, is taken up first: Matter-flux-dominated (MFD), σ < 1, and/or Poynting-flux-dominated (PFD), σ >1? The standard fireball IS model and dissipative photosphere model are MFD, while the ICMART (Internal-Collision-induced MAgnetic Reconnection and Turbulence) model is PFD. Motivated by ICMART model and other relevant problems, such as “jets in a jet” model of AGNs, the author investigates the models from the EMF energy dissipation efficiency, relativistic outflow generation, and σ evolution points of view, and simulates collisions between high-σ blobs to mimic the situation of the interactions inside the PFD jets/outflows by using a 3D SRMHD code which solves the conservative form of the ideal MHD equations. σ b,f is calculated from the simulation results (threshold = 1). The efficiency obtained from this hybrid method is similar to the efficiency got from the energy evolution of the simulations (35.2%). Efficiency is nearly σ independent, which is also confirmed by the hybrid method. σ b,i - σ b,f provides an interesting linear relationship. Results of several parameter studies of EMF energy dissipation efficiency are shown.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Formula for the ionisation rate of an atom or ion in a strong electromagnetic field for numerical simulation

A formula is proposed for calculating the rate of field ionisation of an atom or ion, taking into account both tunnel ionisation and barrier suppression ionisation. Compared with the previous formula proposed in 2018, it more accurately describes the transition region between both ionisations and is determined mainly by two parameters: the ionisation potential of an atom or ion and the amplitude of an external electric field. This makes the presented formula suitable for use in numerical packages simulating the interaction of high-power laser radiation with matter by the particle-in-cell (PIC) method. (paper)

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Theory of resonance fluorescence from a solid-state cavity QED system: Effects of pure dephasing

We theoretically analyze the resonance fluorescence of a solid-state cavity quantum electrodynamics (QED) system that consists of a quantum dot and a cavity. We clarify the effects of pure dephasing by investigating the elastic and inelastic scattering probabilities, the fluorescence power spectrum, and the energy exchange with the environment. Pure dephasing interactions with the environment both enhance nonresonant coupling between the dot and the cavity and enable the pump light to continuously absorb energy from the environment under appropriate conditions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

Epsilon near zero material for electromagnetic energy transport through sub-wavelength channels

Confining and enhancing light within deep subwavelength volumes is key to the enhancement of light-matter interaction with great implications in the control of absorption and emission rates, as well as in attaining high optical nonlinearities and/or gain. Efficient transport of electromagnetic energy through subwavelength channels in the optical regime can dramatically enhance the performance of subwavelength imaging, photovoltaics, sensing and light emission. Current approaches based on plasmonic structures or negative index metamaterials tend to be lossy due to material absorption and have a small bandwidth due to reliance on r esonance behavior. Recently, epsilon-near-zero (ENZ) material has been proposed as a way to achieve efficient subwavelength electromagnetic energy transport. E NZ materials have near-zero dielectric constant (epsilon) in the effective medium limit r esulting in an unusually large effective wavelength even at optical frequencies is thus expected to enable energy squeezing and transfer through subwavelength channels with lower losses over larger bandwidth. The optical properties of materials which is the response to an applied external electromagnetic field can be expressed using the relative permittivity(ε) and the relative permeability(µ) of the medium.

Subramania, Ganapathi S.↗
NASA NTRS1991

A global analysis of the electrodynamic interactions between a space station and the ionospheric plasma environment

A general analysis of the electrodynamic interactions between a space station with two biased platforms and the ionospheric plasma is presented. This problem can be separated into a far-field problem, concerned with the electromagnetic interference surrounding the entire space station, and a near-field problem, concentrated on the interactions in the vicinity of the biased platforms. The far-field problem is solved by application of plasma fluid theory. The space station will generate a radiation field composed mainly of the Alfven waves. This far-field radiation depends on the details of the near-field current collection. Computer particle simulations were performed in the near-field of the biased platform to study the plasma flow field, the sheath structure and the current collection. Approximate analytical solutions to the near-field are also obtained. The far-field and near-field solutions are coupled to provide a global description of the electrodynamic interactions.

Wang, J.↗
DOE OSTI2011

Momentum Spectrum of Cosmic Muons at a Depth of 320 Mwe

Since their discovery, great progress has been achieved in the field of cosmic ray physics particularly towards the understanding of the origin, transport and acceleration mechanisms of the high energy particles that constitute primary cosmic rays, their interaction processes in the galactic and extra galactic media, and also in the Earth's atmosphere. The interaction of primary cosmic ray particles in the Earth's atmosphere leads to the production of a cascade of secondary particles or Extensive Air Showers (EAS) with various components - electromagnetic, hadronic, muon and neutrino components. There is a large number of models to describe these interactions. Many cosmic ray experiments have used a variety of observables in EAS that provide an understanding of the hadronic interactions and also shed some light on the chemical composition of the primary particles. The muon flux at the surface provides a useful tool for the calculations of neutrino fluxes, the reconstruction of EAS and it can serve as a test of various interaction models. The CosmoALEPH detector, whichwas one of the experiments in CosmoLEP used the ALEPH detector at the European Laboratory for Particle Physics, CERN, to measure the muonic component of EAS. Preliminary results have recently shown that the momentum spectrum and charge ratio for cosmic muons measured by CosmoALEPH are well within the world average. This work reports on further improvements in the reconstruction of the cosmic muon events and data analysis. Cosmic muons are produced through interactions of primary cosmic radiation in the atmosphere. They are a component of extensive air showers which can also be measured underground. The CosmoALEPH experiment used the ALEPH detector at the European Laboratory for Particle Physics, CERN, to measure cosmic muon events at a depth of 320 mwe underground. The momentum spectrum and charge ratio of the cosmic muons are measured. The results are compared with the expectations from MC simulations based on different hadronic interaction models.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS2002

Radiative Energy Loss by Galactic Cosmic Rays

Interactions between galactic cosmic rays and matter are a primary focus of the NASA radiation problem. The electromagnetic forces involved are for the most part well documented. Building on previous research, this study investigated the relative importance of the weak forces that occur when a cosmic ray impinges on different types of materials. For the familiar electromagnetic case, it is known that energy lost in the form of radiation is more significant than that lost via contact collisions the rate at which the energy is lost is also well understood. Similar results were derived for the weak force case. It was found that radiation is also the dominant mode of energy loss in weak force interactions and that weak force effects are indeed relatively weak compared to electromagnetic effects.

Ahern, Sean C.↗
NASA NTRS1990

Electron heating in quasi-perpendicular shocks - A Monte Carlo simulation

To study the problem of electron heating in quasi-perpendicular shocks, under the combined effects of 'reversible' motion, in the shock electric potential and magnetic field, and wave-particle interactions a diffusion equation was derived, in the drift (adiabatic) approximation and it was solved by using a Monte Carlo method. The results show that most of the observations can be explained within this framework. The simulation has also definitively shown that the electron parallel temperature is determined by the dc electromagnetic field and not by any wave particle induced heating. Wave-particle interactions are effective in smoothing out the large gradients in phase space produced by the 'reversible' motion of the electrons, thus producing a 'cooling' of the electrons. Some constraints on the wave-particle interaction process may be obtained from a detailed comparison between the simulation and observations. In particular, it appears that the adiabatic approximation must be violated in order to explain the observed evolution of the perpendicular temperature.

Veltri, Pierluigi↗
NASA NTRS1997

Multi-Species Test of Ion Cyclotron Resonance Heating at High Altitudes

Observations of ion distributions and plasma waves obtained by the Dynamics Explorer 1 satellite in the high-altitude, nightside auroral zone are used to study ion energization for three ion species. A number of theoretical models have been proposed to account for the transverse heating of these ion populations. One of these, the ion cyclotron resonance heating (ICRH) mechanism, explains ion conic formation through ion cyclotron resonance with broadband electromagnetic wave turbulence in the vicinity of the characteristic ion cyclotron frequency. The cyclotron resonant heating of the ions by low- frequency electromagnetic waves is an important energy source for the transport of ions from the ionosphere to the magnetosphere. In this paper we test the applicability of the ICRH mechanism to three simultaneously heated and accelerated ion species by modelling the ion conic formation in terms of a resonant wave-particle interaction in which the ions extract energy from the portion of the broadband electromagnetic wave spectrum which includes the ion cyclotron frequency. Using a Monte Carlo technique we evaluate the ion heating produced by the electromagnetic turbulence at low frequencies and find that the wave amplitudes near the ion cyclotron frequencies are sufficient to explain the observed ion energies.

Persoon, A. M.↗
NASA NTRS1997

Multi-Species Test of Ion Cyclotron Resonance Heating at High Altitudes

Observations of ion distributions and plasma waves obtained by the Dynamics Explorer 1 satellite in the high-altitude, nightside auroral zone are used to study ion energization for three ion species. A number of theoretical models have been proposed to account for the transverse heating of these ion populations. One of these, the ion cyclotron resonance heating (ICRH) mechanism, explains ion conic formation through ion cyclotron resonance with broadband electromagnetic wave turbulence in the vicinity of the characteristic ion cyclotron frequency. The cyclotron resonant heating of the ions by low-frequency electromagnetic waves is an important energy source for the transport of ions from the ionosphere to the magnetosphere. In this paper we test the applicability of the ICRH mechanism to three simultaneously heated and accelerated ion species by modelling the ion conic formation in terms of a resonant wave-particle interaction in which the ions extract energy from the portion of the broadband electromagnetic wave spectrum which includes the ion cyclotron frequency. Using a Monte Carlo technique we evaluate the ion heating produced by the electromagnetic turbulence at low frequencies and find that the wave amplitudes near the ion cyclotron frequencies are sufficient to explain the observed ion energies.

Persoon, A. M.↗
DOE OSTI2018

Recent results from the MINERvA experiment

MINERvA is a dedicated neutrino-nucleus scattering experiment with multiple nuclear targets in the Neutrinos from the Main Injector (NuMI) beam line at Fermilab. MINERvA can provide high precision measurements of neutrino interaction cross sections in the 1 to 20 GeV energy range in support to current and future oscillation experiments. MINERvA can also provide information about the structure of protons and neutrons and about the dynamics affecting neutrino-nucleus interactions. The heart of the MINERvA detector is a fine-grained scintillating tracking cham-ber, surrounded by electromagnetic and hadronic calorimeters. Carbon, iron and lead targets are used to study the effect of the nuclear medium on neutrino-induced interactions. In conclusion, this document summarizes the most recent MINERvA results

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS2006

Structurally Integrated Antenna Concepts for HALE UAVs

This technical memorandum describes work done in support of the Multifunctional Structures and Materials Team under the Vehicle Systems Program's ITAS (Integrated Tailored Aero Structures) Project during FY 2005. The Electromagnetics and Sensors Branch (ESB) developed three ultra lightweight antenna concepts compatible with HALE UAVs (High Altitude Long Endurance Unmanned Aerial Vehicles). ESB also developed antenna elements that minimize the interaction between elements and the vehicle to minimize the impact of wing flexure on the EM (electromagnetic) performance of the integrated array. In addition, computer models were developed to perform phase correction for antenna arrays whose elements are moving relative to each other due to wing deformations expected in HALE vehicle concepts. Development of lightweight, conformal or structurally integrated antenna elements and compensating for the impact of a lightweight, flexible structure on a large antenna array are important steps in the realization of HALE UAVs for microwave applications such as passive remote sensing and communications.

Cravey, Robin L.↗
DOE OSTI2015

Onset of stimulated Raman scattering of a laser in a plasma in the presence of hot drifting electrons

Stimulated Raman scattering of a laser in plasmas with energetic drifting electrons was investigated by analyzing the growth of interacting waves during the Raman scattering process. The Langmuir wave and scattered electromagnetic sideband wave grow initially and are dampened after attaining a maximum level that indicates a periodic exchange of energy between the pump wave and the daughter waves. The presence of energetic drifting electrons in the laser-produced plasma influences the stimulated Raman scattering process. The plasma wave generated by Raman scattering may be influenced by the energetic electrons, which enhance the growth rate of the instability. Our results show that the presence of energetic (hot) drifting electrons in a plasma has an important effect on the evolution of the interacting waves. This phenomenon is modeled via two-dimensional particle-in-cell simulations of the propagation and interaction of the laser under Raman instability.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Milli-magnetic monopole dark matter and the survival of galactic magnetic fields

A bstract Dark sectors with Abelian gauge symmetries can interact with ordinary matter via kinetic mixing. In such scenarios, magnetic monopoles of a broken dark U(1) will appear in our sector as confined milli-magnetically charged objects under ordinary electromagnetism. Halo ellipticity constraints are shown to significantly bound the strength of dark magnetic Coulomb monopole interactions. The bound magnetic monopole ground state, which in vacuum is stable and has no magnetic charge or moment, is shown to become quantum mechanically unstable in the presence of an external, ordinary magnetic field. If these states contribute sizably to the local dark matter density, they extract significant energy from the galactic magnetic field. We revise and extend this “Parker Bound” on galactic magnetic energy loss to milli-magnetic monopoles which leads to the strongest existing constraints on these states, satisfying our halo ellipticity bounds, over a wide range of magnetic monopole masses.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗