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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 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Electromagnetic Analysis of ITER Electron Cyclotron Emission Components and Support Structures for the Preliminary Design Review

The ITER electron cyclotron emission (ECE) diagnostic system is located at Design Shield Module (DSM) 2, Equatorial Port (EP) 9 to measure electron temperature profile and electron temperature fluctuations and also to assess nonthermal electron distributions via the oblique view. Therefore, ECE has both radial and oblique views with two couples of mirrors for two different optical views. This ECE diagnostic system shall be exposed to significant power due to unabsorbed electron cyclotron heating power in the plasma. It shall also receive large electromagnetic (EM) loads up to 100 MN/m 3 force density due to the eddy currents generated by the short 16-ms transient plasma disruption. The global EM models of EP12 and EP11 with the worst case of plasma disruption Major Disruption Downward Exponential 16 ms Category III (MD_DW_EXP16MS_CATIII) have been provided by ITER. However, the support structure for these critical components, including four mirrors, is still under the design and development phase, especially during the period of preliminary design reviews (PDRs). For those small in-vessel components that are not modeled explicitly for the PDRs, we can extract the magnetic field (B) data and flux variations (dB/dt) at those locations from the global model and then use the B and dB/dt method to calculate the eddy currents, EM forces, and torques on those components in the local submodels. In conclusion, this paper will present the detailed PDR EM analysis results of the ECE components and support structures.

Electromagnetic↗
DOE OSTI2013

THE ROLE OF SUPERLUMINAL ELECTROMAGNETIC WAVES IN PULSAR WIND TERMINATION SHOCKS

The dynamics of a standing shock front in a Poynting-flux-dominated relativistic flow is investigated by using a one-dimensional, relativistic, two-fluid simulation. An upstream flow containing a circularly polarized, sinusoidal magnetic shear wave is considered, mimicking a wave driven by an obliquely rotating pulsar. It is demonstrated that this wave is converted into large-amplitude electromagnetic waves with superluminal phase speeds by interacting with the shock when the shock-frame frequency of the wave exceeds the proper plasma frequency. The superluminal waves propagate in the upstream, modify the shock structure substantially, and form a well-developed precursor region ahead of a subshock. Dissipation of Poynting flux occurs in the precursor as well as in the downstream region through a parametric instability driven by the superluminal waves. The Poynting flux remaining in the downstream region is carried entirely by the superluminal waves. The downstream plasma is therefore an essentially unmagnetized, relativistically hot plasma with a non-relativistic flow speed, as suggested by observations of pulsar wind nebulae.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Electromagnetic waves near the proton cyclotron frequency: Stereo observations

Transverse, near-circularly polarized, parallel-propagating electromagnetic waves around the proton cyclotron frequency were found sporadically in the solar wind throughout the inner heliosphere. They could play an important role in heating and accelerating the solar wind. These low-frequency waves (LFWs) are intermittent but often occur in prolonged bursts lasting over 10 minutes, named 'LFW storms'. Through a comprehensive survey of them from Solar Terrestrial Relations Observatory A using dynamic spectral wave analysis, we have identified 241 LFW storms in 2008, present 0.9% of the time. They are left-hand (LH) or right-hand (RH) polarized in the spacecraft frame with similar characteristics, probably due to Doppler shift of the same type of waves or waves of intrinsically different polarities. In rare cases, the opposite polarities are observed closely in time or even simultaneously. Having ruled out interplanetary coronal mass ejections, shocks, energetic particles, comets, planets, and interstellar ions as LFW sources, we discuss the remaining generation scenarios: LH ion cyclotron instability driven by greater perpendicular temperature than parallel temperature or by ring-beam distribution, and RH ion fire hose instability driven by inverse temperature anisotropy or by cool ion beams. The investigation of solar wind conditions is compromised by the bias of the one-dimensional Maxwellian fit used for plasma data calibration. However, the LFW storms are preferentially detected in rarefaction regions following fast winds and when the magnetic field is radial. This preference may be related to the ion cyclotron anisotropy instability in fast wind and the minimum in damping along the radial field.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Constraining parameters of white-dwarf binaries using gravitational-wave and electromagnetic observations

The space-based gravitational wave (GW) detector, evolved Laser Interferometer Space Antenna (eLISA) is expected to observe millions of compact Galactic binaries that populate our Milky Way. GW measurements obtained from the eLISA detector are in many cases complimentary to possible electromagnetic (EM) data. In our previous papers, we have shown that the EM data can significantly enhance our knowledge of the astrophysically relevant GW parameters of Galactic binaries, such as the amplitude and inclination. This is possible due to the presence of some strong correlations between GW parameters that are measurable by both EM and GW observations, for example, the inclination and sky position. In this paper, we quantify the constraints in the physical parameters of the white-dwarf binaries, i.e., the individual masses, chirp mass, and the distance to the source that can be obtained by combining the full set of EM measurements such as the inclination, radial velocities, distances, and/or individual masses with the GW measurements. We find the following 2σ fractional uncertainties in the parameters of interest. The EM observations of distance constrain the chirp mass to ∼15%-25%, whereas EM data of a single-lined spectroscopic binary constrain the secondary mass and the distance with factors of two to ∼40%. The single-line spectroscopic data complemented with distance constrains the secondary mass to ∼25%-30%. Finally, EM data on double-lined spectroscopic binary constrain the distance to ∼30%. All of these constraints depend on the inclination and the signal strength of the binary systems. We also find that the EM information on distance and/or the radial velocity are the most useful in improving the estimate of the secondary mass, inclination, and/or distance.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Gyrokinetic electromagnetic particle simulations in triangular meshes with C1 finite elements

The triangular mesh-based gyrokinetic scheme enables comprehensive axis-to-edge studies across the entire plasma volume. Our approach employs triangular finite elements with first-derivative continuity (C1), building on previous work to facilitate gyrokinetic simulations. Additionally, we have adopted the mixed variable/pullback scheme for gyrokinetic electromagnetic particle simulations. The filter-free treatment in the poloidal cross-section with triangular meshes introduces unique features and challenges compared to previous treatments using structured meshes. Our implementation has been validated through benchmarks using ITPA-toroidicity-induced Alfvén eigenmode parameters, showing its capability in moderate to small electron skin depth regimes. Additional examinations using experimental parameters confirm its applicability to realistic plasma conditions.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Neutrino spin oscillations in matter under the influence of gravitational and electromagnetic fields

We derive the new quasi-classical equation for the description of the spin evolution of a neutrino propagating in a curved space-time and interacting with a background matter and an external electromagnetic field. This equation is used to analyze neutrino spin oscillations in these external backgrounds. We obtain the effective Hamiltonian and the transition probability for oscillations of neutrinos when they move in the vicinity of a rotating black hole, surrounded by an accretion disk, and interact with an external magnetic field. The appearance of new resonances in neutrino spin oscillations in this system is considered. The approximate treatment of spin oscillations of radially propagating ultra high energy neutrinos is developed. We also discuss the applications of our results to the description of neutrino spin oscillations in realistic astrophysical media.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Emergent cosmological constant from colliding electromagnetic waves

In this study we advocate the view that the cosmological constant is of electromagnetic (em) origin, which can be generated from the collision of em shock waves coupled with gravitational shock waves. The wave profiles that participate in the collision have different amplitudes. It is shown that, circular polarization with equal amplitude waves does not generate cosmological constant. We also prove that the generation of the cosmological constant is related to the linear polarization. The addition of cross polarization generates no cosmological constant. Depending on the value of the wave amplitudes, the generated cosmological constant can be positive or negative. We show additionally that, the collision of nonlinear em waves in a particular class of Born-Infeld theory also yields a cosmological constant.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Generation and regulation of electromagnetic pulses induced by hybrid laser pulses interacting with solid targets

In inertial confinement fusion, electromagnetic pulses (EMPs) can be produced during high-power laser interacting with solid targets, which are intimately related to laser intensity and laser energy. In this study, EMPs generated by hybrid laser pulses coupling with targets are recorded and analyzed. The results indicate that a single picosecond laser gives birth to the most intense EMPs, but they are remarkably suppressed when a nanosecond laser-shooting target is triggered before the picosecond and femtosecond laser. One possible hypothesis is proposed based on x-rays inducing pre-ablation that generates pre-plasma at the surfaces of the picosecond target and femtosecond target, leading to a sharp drop both in the energy and number of the emitting hot electrons and protons. Here, the findings will deepen our understanding of the mechanism of EMPs' generation and will also open a new avenue to regulate EMPs by hybrid laser pulses.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Printing of electromagnetic interference shielding materials

Here, the proliferation of electronic devices has made electromagnetic interference (EMI) shielding an exponentially growing business. Regulatory requirements change constantly as new technologies continue to emerge. Innovations in materials and new advances in shielding implementation techniques are needed to pass regulatory compliance tests at an affordable cost. Here, we print various EMI shielding materials such as copper, silver and a composite of copper with Fe 3 O 4 using plasma jet printing. Printing enables shields only a few microns thick capable of high shielding effectiveness. Copper's EMI shielding performance is primarily contributed by reflection mechanism, as expected and this is known to cause secondary pollution. A Green Index for EMI shielding, given by the ratio of absorption and reflection contributions to shielding, indicates values lower than 0.1 for printed copper films.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Electromagnetic wave propagation based upon spectral-element methodology in dispersive and attenuating media

SUMMARY We build on mathematical equivalences between Maxwell’s wave equations for an electromagnetic medium and elastic seismic wave equations. This allows us to readily model Maxwell’s wave propagation in the spectral-element codes SPECFEM2D and SPECFEM3D, written for acoustic, viscoelastic and poroelastic seismic wave propagation, providing the ability to handle complex geometries, inherent to finite-element methods and retaining the strength of exponential convergence and accuracy due to the use of high-degree polynomials to interpolate field functions on the elements, characteristic to spectral-element methods (SEMs). Attenuation and dispersion processes related to the frequency dependence of dielectric permittivity and conductivity are also included using a Zener model, similar to shear attenuation in viscoelastic media or viscous diffusion in poroelastic media, and a Kelvin–Voigt model, respectively. Ability to account for anisotropic media is also discussed. Here, we limit ourselves to certain dielectric permittivity tensor geometries, in order to conserve a diagonal mass matrix after discretization of the system of equations. Doing so, simulation of Maxwell’s wave equations in the radar frequency range based on SEM can be solved using explicit time integration schemes well suited for parallel computation. We validate our formulation with analytical solutions. In 2-D, our implementation allows for the modelling of both a transverse magnetic (TM) mode, suitable for surface based reflection ground penetration radar type of applications, and a transverse electric (TE) mode more suitable for crosshole and vertical radar profiling setups. Two 2-D examples are designed to demonstrated the use of the TM and TE modes. A 3-D example is also presented, which allows for the full TEM solution, different antenna orientations, and out-of-plane variations in material properties.

58 GEOSCIENCES↗
DOE OSTI2018

Impact of ejecta morphology and composition on the electromagnetic signatures of neutron star mergers

The electromagnetic transients accompanying compact binary mergers (γ-ray bursts, afterglows and ‘macronovae’) are crucial to pinpoint the sky location of gravitational wave sources. Macronovae are caused by the radioactivity from freshly synthesized heavy elements, e.g. from dynamic ejecta and various types of winds. We study macronova signatures by using multidimensional radiative transfer calculations. We then employ the radiative transfer code SUPERNU and state-of-the-art LTE opacities for a few representative elements from the wind and dynamical ejecta (Cr, Pd, Se, Te, Br, Zr, Sm, Ce, Nd, U) to calculate synthetic light curves and spectra for a range of ejecta morphologies. The radioactive power of the resulting macronova is calculated with the detailed input of decay products. We assess the detection prospects for our most complex models, based on the portion of viewing angles that are sufficiently bright, at different cosmological redshifts (z). The brighter emission from the wind is unobscured by the lanthanides (or actinides) in some of the models, permitting non-zero detection probabilities for redshifts up to z = 0.07. We also find that the nuclear mass model and the resulting radioactive heating rate are crucial for the detectability. While for the most pessimistic heating rate (from the finite range droplet model) no reasonable increase in the ejecta mass or velocity, or wind mass or velocity, can possibly make the light curves agree with the observed near-infrared excess after GRB130603B, a more optimistic heating rate (from the Duflo–Zuker model) leads to good agreement. We conclude that future reliable macronova observations would constrain nuclear heating rates, and consequently help constrain nuclear mass models.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Discontinuities in the electromagnetic fields of vortex beams in the complex source-sink model

An analytical discontinuity is reported in what was thought to be the discontinuity-free exact nonparaxial vortex beam phasor obtained within the complex source-sink model. This discontinuity appears for all odd values of the orbital angular momentum mode. Such discontinuities in the phasor lead to nonphysical discontinuities in the real electromagnetic field components. We identify the source of the discontinuities, and provide graphical evidence of the discontinuous real electric fields for the first and third orbital angular momentum modes. Additionally, a simple means of avoiding these discontinuities is presented.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2021

Spectroscopy of Rydberg states in erbium using electromagnetically induced transparency

We present a study of the Rydberg spectrum in 166 Er for series connected to the 4 f 12 ( 3 H 6 )6s, J c = 13/2 and J c = 11/2 ionic core states using an all-optical detection based on electromagnetically induced transparency in an effusive atomic beam. Identifying approximately 550 individual states, we find good agreement with a multi-channel quantum defect theory (MQDT) which allows assignment of most states to ns or nd Rydberg series. We provide an improved accuracy for the lowest two ionization thresholds to E IP, J c =13/2 = 49260:750(1) cm -1 and E IP, J c =11/2 = 49701:184(1) cm -1 as well as the corresponding quantum defects for all observed series. We identify Rydberg states in five different isotopes, and states between the two lowest ionization thresholds. Our results open the way for future applications of Rydberg states for quantum simulation using erbium and exploiting its special open-shell structure.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2024

A Semi-Analytical Approach for State-Space Electromagnetic Transient Simulation

Here, this paper proposes a semi-analytical approach for efficient and accurate electromagnetic transient (EMT) simulation of a power grid. The approach first derives a high-order semi-analytical solution (SAS) of the grid’s state-space EMT model using the differential transformation (DT), and then evaluates the solution over enlarged, variable time steps to significantly accelerate the simulations while maintaining its high accuracy on detailed fast EMT dynamics. The approach also addresses switches during large time steps by using a limit violation detection algorithm with a binary search-enhanced quadratic interpolation. Case studies are conducted on EMT models of the IEEE 39-bus system and large-scale systems to demonstrate the merits of the new simulation approach against traditional numerical methods.

electromagnetic transient↗
DOE OSTI2024

Equivalent-Circuit Models of Grid-Forming IBRs for Electromagnetic-Transient Simulations

We derive equivalent-circuit models of control- and physical-layer subsystems of grid-forming (GFM) inverter-based resources (IBRs) for electromagnetic-transient (EMT) simulations. Three different primary controllers are considered: Droop, Virtual Synchronous Machine (VSM), and dispatchable Virtual Oscillator Control (dVOC). In addition, the models include cascaded voltage- and current-control loops, and LCL output filters. Simulations for a single-inverter setup and for a network of five inverters in a modified IEEE 14-bus topology are presented. The equivalent-circuit models simulated with analog electronic circuit-simulator software (in our case, LTspice) offer the same accuracy, and with no explicit tuning of the solver, lower computational burden compared to block-diagram-based implementations in commercial off-the-shelf EMT software (in our case, MATLAB-Simulink).

electromagnetic transient simulation↗
DOE OSTI2016

Space-time development of electromagnetic and hadronic showers and perspectives for novel calorimetric techniques

The performance of hadronic calorimeters will be a key parameter at the next generation of High Energy Physics accelerators. A detector combining fine granularity with excellent timing information would prove beneficial for the reconstruction of both jets and electromagnetic particles with high energy resolution. In this work, the space and time structure of high energy showers is studied by means of a Geant4-based simulation toolkit. In particular, the relevant time scales of the different physics phenomena contributing to the energy loss are investigated. A correlation between the fluctuations of the energy deposition of high energy hadrons and the time development of the showers is observed, which allows for an event-by-event correction to be computed to improve the energy resolution of the calorimeter. Lastly, these studies are intended to set the basic requirements for the development of a new-concept, total absorption time-imaging calorimeter, which seems now within reach thanks to major technological advancements in the production of fast scintillating materials and compact photodetectors.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Design and Beam Test Results for the sPHENIX Electromagnetic and Hadronic Calorimeter Prototypes

The super Pioneering High Energy Nuclear Interaction eXperiment (sPHENIX) at the Relativistic Heavy Ion Collider (RHIC) will perform high precision measurements of jets and heavy flavor observables for a wide selection of nuclear collision systems, elucidating the microscopic nature of strongly interacting matter ranging from nucleons to the strongly coupled quark-gluon plasma. A prototype of the sPHENIX calorimeter system was tested at the Fermilab Test Beam Facility as experiment T-1044 in the spring of 2016. The electromagnetic calorimeter (EMCal) prototype is composed of scintillating fibers embedded in a mixture of tungsten powder and epoxy. The hadronic calorimeter (HCal) prototype is composed of tilted steel plates alternating with plastic scintillator. Results of the test beam reveal the energy resolution for electrons in the EMCal is $2.8\%\oplus~15.5\%/\sqrt{E}$ and the energy resolution for hadrons in the combined EMCal plus HCal system is $13.5\%\oplus 64.9\%/\sqrt{E}$. These results demonstrate that the performance of the proposed calorimeter system satisfies the sPHENIX specifications.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Design and Beam Test Results for the 2-D Projective sPHENIX Electromagnetic Calorimeter Prototype

sPHENIX is a new experiment under construction for the Relativistic Heavy Ion Collider at Brookhaven National Laboratory which will study the quark-gluon plasma to further the understanding of quantum chromodynamics (QCP) matter and interactions. A prototype of the sPHENIX electromagnetic calorimeter (EMCal) was tested at the Fermilab Test Beam Facility in Spring 2018 as experiment T-1044.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗