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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 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Performance Analysis of Electrodynamic Screens Based on Residual Particle Size Distribution

Dust accumulation on the optical surfaces of solar collectors causes significant losses in their energy yield. Fine dust particles, compared with coarse ones, contribute significantly more in the performance loss, assuming identical surface mass concen- tration. This study examines the performance of different electro- dynamic screen (EDS) prototypes, operated under different con- ditions, in removing fine dust particles in the laboratory environ- ment. After going through several cycles of dust deposition and cleaning using EDS, the dust residue left on each EDS prototype is collected and analyzed using a Horiba particle size distribution (PSD) analyzer. The PSD analyses determine which EDS design has performed superior in removing a given size range and in which operational condition. Here, the results are advantageous in the optimization procedure of EDS to attain maximum dust removal efficiency and minimum optical interference.

14 SOLAR ENERGY↗
DOE OSTI2016

Nonlinear normal modes in electrodynamic systems: A nonperturbative approach

We consider electromagnetic nonlinear normal modes in cylindrical cavity resonators filled with a nonlinear nondispersive medium. The key feature of the analysis is that exact analytic solutions of the nonlinear field equations are employed to study the mode properties in detail. Based on such a nonperturbative approach, we rigorously prove that the total energy of free nonlinear oscillations in a distributed conservative system, such as that considered in our work, can exactly coincide with the sum of energies of the normal modes of the system. This fact implies that the energy orthogonality property, which has so far been known to hold only for linear oscillations and fields, can also be observed in a nonlinear oscillatory system.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Electrodynamic Calculation of Effective Electromagnetic Parameters of a Dielectric Medium with Metallic Nanoparticles of a Given Size

The frequency dependence of the effective complex permittivity and effective complex permeability of a heterostructure based on a dielectric medium containing metallic nanoparticles of spherical shape is calculated by an original method. In contrast to the Bruggeman [21] and the Maxwell Garnett [17] approaches, which use the quasi-static approximation in calculations, a nonuniform distribution of electromagnetic fields inside metallic particles is calculated, which allows the analysis of the electromagnetic parameters of the heterostructure not only as a function of frequency but also as a function of the nanoparticle size. It is shown that the plasmon resonant frequency decreases with increasing both the size and the concentration of particles in the heterostructure. It is also shown that a dielectric medium containing nonmagnetic metallic nanoparticles exhibits diamagnetic properties. In this case, the position of the maximum on the frequency dependence of the imaginary part of the magnetic susceptibility coincides with the relaxation frequency of charge carriers. The calculated spectra of the real and imaginary components of the permittivity of the heterostructure with a size of metallic particles less than 10 nm are in good agreement with Bruggeman calculations; however, the agreement with Maxwell Garnett calculations is observed only at nanoparticle concentrations lower than 10{sup –6}.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Leading and Next-to-Leading Logarithmic Approximations in Quantum Electrodynamics

Abstrac t —Methods: for determination of QED radiative corrections in the leading and next-to- leading logarithmic approximations are described. Analytical solutions to the QED evolution equations for electron structure functions are presented. Some examples of applying the methods described to construction of the high-precision description of processes in high-energy accelerators are considered. A case of the calculation of higher-order corrections to the muon decay spectrum is considered in detail. Use of the approaches developed to justify methods of radiation return and direct measurement of the QED running constant is discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Two-dimensional electrodynamic structure of the normal glow discharge in an axial magnetic field

Results are presented from numerical simulations of an axisymmetric normal glow discharge in molecular hydrogen and molecular nitrogen in an axial magnetic field. The charged particle densities and averaged azimuthal rotation velocities of electrons and ions are studied as functions of the gas pressure in the range of 1–5 Torr, electric field strength in the range of 100–600 V/cm, and magnetic field in the range of 0.01–0.3 T. It is found that the axial magnetic field does not disturb the normal current density law.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2017

Photon electrodynamics and photon structure as a bunch of one of many possible states of electromagnetic field

Fundamental laws of conservation are used to show that electromagnetic field is generally represented (even in vacuum at ρ = 0 and j = 0) using four vectors D, E, B, and H with different equations of state (material equations) that are linear for electromagnetic waves and nonlinear for photons and particles. An equation that describes different states of electromagnetic field (i.e., different but not arbitrary relationships of field vectors E, H, D, and B) is derived. It is shown that electromagnetic wave and photon are different states of electromagnetic field that exhibit different dependences of energy density on field vectors. Partial analytical solutions are obtained for a photon (spatially localized bunch of electromagnetic field energy) that propagates at a velocity of light along a single (as distinct from electromagnetic wave) direction.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Semi-classical Electrodynamics: A Short Note

I have previously claimed the key to understanding the numerical value of the fine structure constant is near-field corrections which terminate integrals at low virtual photon energies, thus obverting an infrared divergence common to many QED calculations. I have since switched to a physics-based calculation of the near-field corrections, instead of the previously used educated guess. The relevant equations are presented here.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Conduct Performance Validation of the Electrodynamic Shield (EDS) Induced Cleaning Under Realistic Environmental Soiling Conditions: CRADA Number CRD-21-17861 (Cooperative Research and Development Final Report)

NREL will work with the Participant to perform accelerated long-term durability and other standard durability tests for prototypes to help demonstrate the reliability of the technology for PV applications. NREL will test commercially relevant-sized prototypes under realistic environmental soiling conditions to correlate dust removal efficacy for improving the PV output under standard solar conditions. Measurements will include voltage-current characterization in solar simulators before and after dust cleaning.

14 SOLAR ENERGY↗
DOE OSTI2016

FREELY DECAYING TURBULENCE IN FORCE-FREE ELECTRODYNAMICS

Freely decaying, relativistic force-free turbulence is studied for the first time. We initiate the magnetic field at a short wavelength and simulate its relaxation toward equilibrium on two- and three-dimensional periodic domains in both helical and nonhelical settings. Force-free turbulent relaxation is found to exhibit an inverse cascade in all settings and in three dimensions to have a magnetic energy spectrum consistent with the Kolmogorov 5/3 power law. Three-dimensional relaxations also obey the Taylor hypothesis; they settle promptly into the lowest-energy configuration allowed by conservation of the total magnetic helicity. However, in two dimensions, the relaxed state is a force-free equilibrium whose energy greatly exceeds the Taylor minimum and that contains persistent force-free current layers and isolated flux tubes. We explain this behavior in terms of additional topological invariants that exist only in two dimensions, namely the helicity enclosed within each level surface of the magnetic potential function. The speed and completeness of turbulent magnetic free-energy discharge could help account for rapidly variable gamma-ray emission from the Crab Nebula, gamma-ray bursts, blazars, and radio galaxies.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Traveling-Wave-Based Electrodynamic Switch for Concurrent Dual-Polarity Ion Manipulations in Structures for Lossless Ion Manipulations

In this work, we describe the development of a dual-polarity traveling-wave (TW) structures for lossless ion manipulations (SLIM) ion mobility spectrometry (IMS) device capable of switching both positive and negative ions that are traveling simultaneously along the same path to different regions of the SLIM. Through simulations, the routing efficiency of the SLIM TW switch was compared to a SLIM direct-current-based (DC) switch developed previously for IMS-MS. We also report on the initial experimental evaluation of a dual-polarity SLIM platform, which uses the TW-based ion switch to achieve higher resolution multipass serpentine ultralong path with extended routing (SUPER) IMS separations. Overall, these results show that the dual-polarity TW switch is not only as effective as DC switching in terms of routing efficiency but also is agnostic to the polarity of the ions being routed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗