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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

A Continuous-Discontinuous Galerkin Method for Electromagnetic Simulations Based on an All-Frequency Stable Formulation

In this paper, a potential-based partial-differential formulation, called the all-frequency stable formulation, is presented for the accurate and robust simulation of electromagnetic problems at all frequencies. Due to its stability from (near) dc to microwave frequencies, this formulation can be applied to simulate wide-band and multiscale problems without encountering the infamous low-frequency breakdown issue or applying basis function decompositions such as the tree-cotree splitting technique. To provide both efficient and flexible numerical solutions to the electromagnetic formulation, a mixed continuous-discontinuous Galerkin (CDG) method is proposed and implemented. In regions with homogeneous media, the continuous Galerkin method is employed to avoid the introduction of duplicated degrees of freedom (DoFs) on the elemental interfaces, while on the interfaces of two different media, the discontinuous Galerkin method is applied to permit the jump of the normal components of the electromagnetic fields. Numerical examples are provided to validate and demonstrate the proposed numerical solver for problems in a wide electromagnetic spectrum.

Yan, Su↗
DOE OSTI2023

Electromagnetic Radiation Effects on MgO-Based Magnetic Tunnel Junctions: A Review

Magnetic tunnel junctions (MTJs) have been widely utilized in sensitive sensors, magnetic memory, and logic gates due to their tunneling magnetoresistance. Moreover, these MTJ devices have promising potential for renewable energy generation and storage. Compared with Si-based devices, MTJs are more tolerant to electromagnetic radiation. In this review, we summarize the functionalities of MgO-based MTJ devices under different electromagnetic irradiation environments, with a focus on gamma-ray radiation. We explore the effects of these radiation exposures on the MgO tunnel barriers, magnetic layers, and interfaces to understand the origin of their tolerance. This review enhances our knowledge of the radiation tolerance of MgO-based MTJs, improves the design of these MgO-based MTJ devices with better tolerances, and provides information to minimize the risks of irradiation under various irradiation environments. This review starts with an introduction to MTJs and irradiation backgrounds, followed by the fundamental properties of MTJ materials, such as the MgO barrier and magnetic layers. Then, we review and discuss the MTJ materials and devices’ radiation tolerances under different irradiation environments, including high-energy cosmic radiation, gamma-ray radiation, and lower-energy electromagnetic radiation (X-ray, UV–vis, infrared, microwave, and radiofrequency electromagnetic radiation). In conclusion, we summarize the radiation effects based on the published literature, which might benefit material design and protection.

42 ENGINEERING↗
DOE OSTI2018

Generating a heated fluid using an electromagnetic radiation-absorbing complex

A vessel including a concentrator configured to concentrate electromagnetic (EM) radiation received from an EM radiation source and a complex configured to absorb EM radiation to generate heat. The vessel is configured to receive a cool fluid from the cool fluid source, concentrate the EM radiation using the concentrator, apply the EM radiation to the complex, and transform, using the heat generated by the complex, the cool fluid to the heated fluid. The complex is at least one of consisting of copper nanoparticles, copper oxide nanoparticles, nanoshells, nanorods, carbon moieties, encapsulated nanoshells, encapsulated nanoparticles, and branched nanostructures. Further, the EM radiation is at least one of EM radiation in an ultraviolet region of an electromagnetic spectrum, in a visible region of the electromagnetic spectrum, and in an infrared region of the electromagnetic spectrum.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Quantum metrology of low frequency electromagnetic modes with frequency upconverters

We describe the RF Quantum Upconverter (RQU) and describe its application to quantum metrology of electromagnetic modes between dc and the Very High Frequency band (VHF) (≲300MHz). The RQU uses a Josephson interferometer made up of superconducting loops and Josephson junctions to implement a parametric interaction between a low-frequency electromagnetic mode (between dc and VHF) and a mode in the microwave C Band (~ 5GHz), analogous to the radiation pressure interaction between electromagnetic and mechanical modes in cavity optomechanics. The RQU can operate as a quantum-limited op-amp, or use protocols from optomechanics to implement non-classical measurement protocols equivalent to those used in cavity optomechanics, including back-action evading (BAE) measurements, sideband cooling, and two-mode squeezing. Furthermore, these protocols enable experiments using dc-VHF electromagnetic modes as quantum sensors.

Kuenstner, Stephen E.↗
DOE OSTI2018

Models of the Dynamics of Spatially Separated Broadband Electromagnetic Fields Interacting with Resonant Atoms

The Markov model of spontaneous emission of an atom localized in a spatial region with a broadband electromagnetic field with zero photon density is considered in the conditions of coupling of the electromagnetic field with the broadband field of a neighboring space. The evolution operator of the system and the kinetic equation for the atom are obtained. It is shown that the field coupling constant affects the rate of spontaneous emission of the atom, but is not manifested in the atomic frequency shift. The analytic expression for the radiative decay constant for the atom is found to be analogous in a certain sense to the expression for the decay constant for a singly excited localized ensemble of identical atoms in the conditions when the effect of stabilization of its excited state by the Stark interaction with the vacuum broadband electromagnetic field is manifested. The model is formulated based on quantum stochastic differential equations of the non- Wiener type and the generalized algebra of the Ito differential of quantum random processes.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Wave Nature of the Transverse Doppler Effect and the “Red” and “Blue” Frequency Shift Anomaly in an Electromagnetic Wave from a Moving Radiation Source

The electromagnetic field of a harmonic oscillator moving at a constant velocity has been analyzed. The expression for calculating the Doppler frequency shift at relativistic velocities of its motion is derived using the classical electromagnetic theory. It is shown that the transverse Doppler effect is a special case and also differs from zero in the wave theory. With an increasing velocity of the radiation source, the “red” frequency shift in an electromagnetic wave prevails over the “blue” shift more strongly. The noncontradictory nature of the proposed model relative to the well-known experimental data has been demonstrated.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Utah FORGE: LBNL Reports on VEMP Electromagnetic Data Collection and Processing - 2024

This archive contains reports related to Vertical Electromagnetic Profiling (VEMP) tool data collection and processing at Utah FORGE in 2024. The first report describes LBNL's effort to collect electromagnetic geophysical data with the tool in well 78-32B and a downhole electrode in well 16A. The second report describes the final data acquisition and processing of the VEMP electromagnetic data collected at the Utah FORGE site in May of 2024. Also included are a noise analysis as well as a comparison of the data to numerical models. This was originally presented as a paper at the 2025 Stanford Geothermal Workshop.

15 GEOTHERMAL ENERGY↗
DOE OSTI2017

Numerical Research on Magnetic Field, Temperature Field and Flow Field During Melting and Directionally Solidifying TiAl Alloys by Electromagnetic Cold Crucible

The electromagnetic cold crucible (EMCC) technique is an effective method to melt and directionally solidify reactive and high-temperature materials without contamination. The temperature field and fluid flow induced by the electromagnetic field are very important for melting and controlling the microstructure. In this article, a 3D EMCC model for calculating the magnetic field in the charges (TiAl alloys) using the T-Ω finite element method was established and verified. Magnetic fields in the charge under different electrical parameters, positions and dimensions of the charge were calculated and analyzed. The calculated results show that the magnetic field concentrates in the skin layer, and the magnetic flux density (B) increases with increasing of the frequency, charge diameter and current. The maximum B in the charge is affected by the position of the charge in EMCC (h{sub 1}) and the charge height (h{sub 2}), which emerges at the middle of coils (h{sub c}) when the relationship of h{sub c} < h{sub 1} + h{sub 2} < h{sub c} + δ is satisfied. Lower frequency and smaller charge diameter can improve the uniformity of the magnetic field in the charge. Consequently, the induced uniform electromagnetic stirring weakens the turbulence and improves temperature uniformity in the vicinity of the solid/liquid (S/L) interface, which is beneficial to forming a planar S/L interface during directional solidification. Based on the above conclusions, the TiAlNb alloy was successfully melted with lower power consumption and directionally solidified by the square EMCC.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Optimized Electromagnetic Fields Levitate Bulk Metallic Materials

The bulk metallic electromagnetic levitation technique has a promising application prospect in condensed physics and materials science. In order to resolve the problem of weak levitation force and the small size of samples, an optimized solution based on finite element analysis (FEA) is developed to seek the best electromagnetic field distribution in the levitation zone. The influence of material properties on the distribution of magnetic flux density, surface pressure, and the Lorentz force were studied by the FEA method with various sample sizes of titanium and copper balls. The levitation capability of cylindrical coil system which consists of a single-layer coil with an inner diameter of 30 mm and the levitated object with a diameter of 20 mm was analyzed. To keep a balance between the turn number and increment efficiency of force, the best number of 7 turns is confirmed. Then, two types of optimized coils were predicted by numerical simulations, and the levitation force is improved drastically. The double-layer coil displays an outstanding levitation capability owing to the strong electromagnetic field generated by multilayer turns. In addition, 5 to 50 g aluminum, titanium, copper, and nickel are levitated by the above three kinds of coils and the levitation capacities are validated from the recorded data of the minimum operating current that can levitate the samples. The experimental results show good agreements with the simulation results, and the minimum current for optimized coils is reduced efficiently.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Magnetic Behavior of Ni/NiO Core–Shell Nanoparticles under Electromagnetic Waves for Oil–Water Interfacial Tension Reduction

The increasing demand for oil and gas has led to a hope of developing more efficient recovery methods. It is well known that nanoparticles adsorbed at the oil–water interface, but there is no consensus that has been reached on whether magnetic nanoparticles under electromagnetic waves affect the interfacial tension. In this paper, nickel/nickel oxide nanoparticles have been synthesized using sol–gel auto combustion method. The product was characterized using x-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, Fourier transforms infrared spectroscopy and vibrating sample magnetometer. The results show the Ni/NiO phases and the ferromagnetic nature of the sample. The Ni/NiO nanofluids were prepared to investigate the effect on oil–water interfacial tension in enhanced oil recovery under electromagnetic waves using an inverted pendant drop method. The results show a significant decrease in interfacial tension under electromagnetic waves of frequency 2.2 kHz at low wt.% of Ni/NiO and at room temperature. The decrease in the interfacial tension has been observed by increasing the temperature to 90 °C using temperature controller. The decrease in the interfacial tension could be due to the interaction of oscillating B-field of waves and magnetic domains of adsorbing nanoparticles at the oil–water interface which disturbed the oil–water interface.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Measurement of the environmental broadband electromagnetic waves in a mid-size European city

In this paper, the level of exposure to broadband radiofrequency electromagnetic field in a mid-size European city was evaluated in accordance with the International Commission on Non-ionizing Radiation Protection guidelines from 1998. With the aim to analyse all the potential electromagnetic waves present in the city up to 18 GHz, a total of 271 locations distributed along Terrassa (Spain) have been measured. To show the results in an easy-to-interpret way by the citizen, the results have been represented in a set of raster maps. The measurement results obtained showed that the electromagnetic wave measured in all broadband frequency range along the city is much lower than the safety level according to the international regulations for both public and occupational sectors.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Enhancing isotope mixing in U-10Mo downblend castings with electromagnetic stirring

Uranium alloyed with 10 wt percent molybdenum (U-10Mo) is the proposed fuel for use in the United States’ high-performance research reactors. The U-10Mo fuel is fabricated by a two-step casting process that downblends highly enriched uranium with depleted uranium (DU) and/or natural uranium (NU) and subsequently alloys the resulting high-assay low-enriched uranium (HALEU) with Mo. Currently, a two-step casting process is needed to meet the ingots’ U-235 enrichment homogeneity specifications. This work demonstrates the ability to provide more homogeneous U-235 distributions during downblend casting by using zirconia for crucibles rather than graphite. When graphite is used as a crucible, the electromagnetic field produced by the induction heater couples directly with the graphite. Zirconia is nonconducting in this study, and therefore does not couple with the field. The induction field couples directly with the metal, and causes electromagnetic stirring (EMS) in the molten metal pool. Eight downblend casting experiments were carried out in this work. Four were performed with zirconia crucibles and four with graphite crucibles. The U-235 enrichment was measured at nine discrete points in each casting using laser ablation multi-collector inductively coupled mass spectrometry (LA-MC-ICP-MS). The enrichment homogeneity was approximately eight times better in zirconia crucible castings than in graphite crucible castings as measured by the plate enrichment range and enrichment coefficient of variation. The results show a single casting step could be used to meet USHPRR enrichment specifications if electromagnetic stirring is present during casting. A related investigation was carried out to determine whether it is appropriate to measure enrichment on as-cast ingots or whether heat treated specimens should be used to accurately characterize enrichment. The results show that the as-cast microstructure plays a significant role in enrichment homogeneity. It is recommended that all enrichment measurements be done after the homogenization heat treatment typical of U-10Mo processing.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Electromagnetic fields from quantum sources in heavy-ion collisions

We compute the electromagnetic field created by an ultrarelativistic charged particle in vacuum at distances comparable to the particle Compton wavelength. The wave function of the particle is governed by the Klein-Gordon equation,for a scalar particle, or the Dirac equation, for a spin-half particle. The produced electromagnetic field is essentially different in magnitude and direction from the Coulomb field, induced by a classical point charge, due to the quantum diffusion effect. Therefore, a realistic computation of the electromagnetic field produced in heavy-ion collisions must be based upon the full quantum treatment of the valence quarks.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Experimental study of electromagnetic wave scattering from a gyrotropic gaseous plasma column

We experimentally demonstrate the controlled scattering of incident transverse-electric electromagnetic waves from a gyrotropic magnetized plasma cylindrical discharge. Scattered electromagnetic waves can bend left and right by changing the external magnetic field of a plasma rod. Measured scattered wavefronts are in good agreement with electromagnetic simulations. A gyrotropic response is observed for incident wave frequencies ranging from 3.5 to 5.6 GHz for conditions corresponding to a ratio of cyclotron frequency to plasma frequency, ω ce /ω p ≈ 0.16. In conclusion, the observation of a gyrotropic response from cylindrical plasma discharges paves the way for their use as building blocks for future devices such as magnetized plasma photonic crystals, topological insulators, plasma metamaterials, non-reciprocal waveguide structures, and other devices, which require a tunable gyrotropic response from centimeter to meter-scale materials with application-specific geometry.

42 ENGINEERING↗
DOE OSTI2022

Quasilinear theory of general electromagnetic fluctuations including discrete particle effects for magnetized plasmas: General analysis

The general quasilinear Fokker–Planck kinetic equation for the gyrophase-averaged plasma particle distribution functions in magnetized plasmas is derived, making no restrictions on the energy of the particles and on the frequency of the electromagnetic fluctuations and avoiding the often made Coulomb approximation of the electromagnetic interactions. Here, the inclusion of discrete particle effects breaks the dichotomy of nonlinear kinetic plasma theory divided into the test particle and the test fluctuation approximation because it provides expression of both the non-collective and collective electromagnetic fluctuation spectra in terms of the plasma particle distribution functions. Within the validity of the quasilinear approach, the resulting full quasilinear transport equation can be regarded as a determining nonlinear equation for the time evolution of the plasma particle distribution functions.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Electromagnetic particle injector for fast time response disruption mitigation in tokamaks

A novel, rapid time-response, disruption mitigation system referred to as the electromagnetic particle injector (EPI) is described. This method can accurately deliver the radiative payload to the plasma center on a <10 ms time scale, much faster, and deeper, than what can be achieved using conventional methods. The EPI system accelerates a sabot electromagnetically. The sabot is a metallic capsule that can be accelerated to desired velocities by an electromagnetic impeller. At the end of its acceleration, within 2 ms, the sabot will release a radiative payload, which is composed of low-z granules, or a shell pellet containing smaller pellets. The primary advantage of the EPI concept over gas propelled systems is its potential to meet short warning time scales, while accurately delivering the required particle size and materials at the velocities needed for achieving the required penetration depth in high power ITER-scale discharges for thermal and runaway current disruption mitigation. In conclusion, the present experimental tests from a prototype system have demonstrated the acceleration of a 3.2 g sabot to over 150 m s –1 within 1.5 ms, consistent with the calculations, giving some degree of confidence that larger ITER-scale injector can be developed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Prototype tests of the electromagnetic particle injector-2 for fast time response disruption mitigation in tokamaks

Predicting and controlling disruptions is an important and urgent issue for ITER. Some disruptions with a short warning time may be unavoidable. For these cases, a fast time response disruption mitigation method is essential. Experimental tests on a prototype system of a novel, rapid time-response disruption mitigation system being developed for tokamak-based reactors and as a backup option for ITER, referred to as the electromagnetic particle injector (EPI), have been able to verify the primary advantages of the concept. These are its ability to meet short warning time scales of <10 ms while attaining the projected high velocities for deep radiative payload penetration in reactor-scale plasmas. The EPI relies on an electromagnetic propulsion system. A metallic sabot is accelerated electromagnetically to the required velocities (>1 km s -1 ) within 2 ms, at which point it releases a radiative payload consisting of a shell pellet or well-defined microspheres. Initial experimental tests from the prototype system show attainment of over 600 m s -1 in about 1 ms. Finally, essential aspects of payload separation from the sabot and sabot capture have also been demonstrated at 200 m s -1 , and the method can be extended to over 2 km s -1 .

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

Fractional Operators Applied to Geophysical Electromagnetics

A growing body of applied mathematics literature in recent years has focused on the application of fractional calculus to problems of anomalous transport. In these analyses, the anomalous transport (of charge, tracers, fluid, etc.) is presumed attributable to long–range correlations of material properties within an inherently complex, and in some cases self-similar, conducting medium. Rather than considering an exquisitely discretized (and computationally intractable) representation of the medium, the complex and spatially correlated heterogeneity is represented through reformulation of the governing equation for the relevant transport physics such that its coefficients are, instead, smooth but paired with fractional–order space derivatives. Here we apply these concepts to the scalar Helmholtz equation and its use in electromagnetic interrogation of Earth’s interior through the magnetotelluric method. We outline a practical algorithm for solving the Helmholtz equation using spectral methods coupled with finite element discretizations. Execution of this algorithm for the magnetotelluric problem reveals several interesting features observable in field data: long–range correlation of the predicted electromagnetic fields; a power–law relationship between the squared impedance amplitude and squared wavenumber whose slope is a function of the fractional exponent within the governing Helmholtz equation; and, a non–constant apparent resistivity spectrum whose variability arises solely from the fractional exponent. In geologic settings characterized by self–similarity (e.g. fracture systems; thick and richly–textured sedimentary sequences, etc.) we posit that these diagnostics are useful for geologic characterization of features far below the typical resolution limit of electromagnetic methods in geophysics.

58 GEOSCIENCES↗