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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Axial Flux Brushless Permanent Magnet Electrical Machine Rotor

An axial flux brushless permanent magnet electrical machine having a stator and at least one rotor. The rotor includes a Halbach array of magnets with at least four magnets per magnetic cycle. The rotor magnets are contained within pockets in the rotor. The pockets are formed with magnet pocket walls being radial walls, active surface walls, and/or inactive surface walls where the walls retain the magnets within the pockets.

Ricci, Michael Richard↗
NASA NTRS1977

Electrical, magnetic, and optical properties of the tetrathiafulvalene /TTF/ pseudohalides, /TTF/12/SCN/7 and /TTF/12/SeCN/7

The electrical, magnetic, and optical properties of charge-transfer salts containing tetrathiafulvalene (TTF) and the pseudohalides, thiocyanate (SCN) and selenocyanate (SeCN), have been investigated. These salts are quasi-one-dimensional compounds containing cation radicals only, in contrast to a cation-radical-anion-radical system, such as tetrathiafulvalene tetracyanoquinodimethane (TTF) (TCNQ). Measurements of electrical conductivity, thermoelectric power, and optical reflectivity of single crystals of the nonstoichiometric salts (TTF)12(SCN)7 and (TTF)12(SeCN)7 show metal-like characteristics above 200 K (high-temperature region). The conductivities at room temperature are approximately 750 mho/cm comparable to those found in (TTF) (TCNQ), and increase with decreasing temperature down to approximately 200 K. The thermoelectric power at room temperature is small and positive (approximately 9 microvolts/deg K), and decreases linearly with decreasing temperature in this region (as expected for metal-like hole conduction along the TTF chains). The ESR intensity, however, decreases with decreasing temperature above 200 K. At 170 K a metal-nonmetal transition occurs, and the transport and magnetic properties below this temperature are characteristic of a semiconducting state.

Somoano, R. B.↗
DOE OSTI2021

Recent Advances in Analysis and Design of Axial Flux Permanent Magnet Electric Machines

Axial flux permanent magnet machines (AFPM) are popular for applications that benefit from high torque density and an axially compact form factor, such as in-wheel traction drives. Although the radial flux permanent magnet machine (RFPM) and the AFPM work based on the same underlying principle, the differences in their geometry introduce complexities in analysis of the AFPM. In this paper, the different AFPM design variants, their sizing approaches, computationally efficient design optimization techniques, and manufacturing techniques reported in literature are reviewed. In addition to classical AFPM machines, emerging variants and research opportunities with potential to push the boundaries of electric machine technology are reviewed. These include bearingless AFPMs, magnetically geared AFPMs, and combined radial-axial flux machines.

Nishanth, FNU↗
DOE OSTI2023

Formation of turing patterns in strongly magnetized electric discharges

Abstract Pattern formation and self-organization in many biological and non-biological systems can be explained through Turing’s activator-inhibitor model. Here we show how this model can be employed to describe the formation of filamentary structures in a low-pressure electric discharge exposed to a strong magnetic field. Theoretical investigation reveals that the fluid equations describing a magnetized plasma can be rearranged to take the mathematical form of Turing’s activator-inhibitor model. Numerical simulations based on the equations derived from this approach could reproduce the various patterns observed in the experiments. Also, it is shown that a density imbalance between electrons and ions exists in the bulk of the magnetized plasma that generates an electric field structure transverse to the applied magnetic field. This electric field is responsible for the stability of the filamentary patterns in the magnetized plasma over time scales much longer than the characteristic time scales of the electric discharge.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Theory of electric, magnetic, and toroidal polarizations in crystalline solids with applications to hexagonal lonsdaleite and cubic diamond

Multipolar order in bulk crystalline solids is characterized by multipole densities-denoted as polarizations in this work-that cannot be cleanly defined using the concepts of classical electromagnetism. Here we use group theory to overcome this difficulty and present a systematic study of electric, magnetic, and toroidal multipolar order in crystalline solids. Based on our symmetry analysis, we identify five categories of polarized matter, each of which is characterized by distinct features in the electronic band structure. For example, Rashba spin splitting in electropolar bulk materials like wurtzite represents the electric dipolarization in these materials. We also develop a general formalism of indicators for individual multipole densities that provide a physical interpretation and quantification of multipolar order. Our work clarifies the relation between patterns of localized multipoles and macroscopic multipole densities they give rise to. To illustrate the general theory, we discuss its application to polarized variants of hexagonal lonsdaleite and cubic diamond structures. In conclusion, our work provides a general framework for classifying and expanding current understanding of multipolar order in complex materials.

36 MATERIALS SCIENCE↗
NASA NTRS1991

Positive holes in magnesium oxide - Correlation between magnetic, electric, and dielectric anomalies

The present magnetic susceptibility investigation of high purity MgO single crystals notes an anomally at 800 K which is associated with increasing electrical conductivity, a rise in static dielectric constant from 9 to 150, and the appearance of a pronounced positive surface charge. These phenomena can be accounted for in terms of peroxy defects which represent self-trapped, spin-paired positive holes at Mg(2+) vacancy sites. The holes begin to decouple their spins above 600 K.

Batllo, F.↗
DOE OSTI2024

Controlling the helicity of light by electrical magnetization switching

Controlling the intensity of emitted light and charge current is the basis of transferring and processing information. By contrast, robust information storage and magnetic random-access memories are implemented using the spin of the carrier and the associated magnetization in ferromagnets. In this study, the missing link between the respective disciplines of photonics, electronics and spintronics is to modulate the circular polarization of the emitted light, rather than its intensity, by electrically controlled magnetization. Here we demonstrate that this missing link is established at room temperature and zero applied magnetic field in light-emitting diodes through the transfer of angular momentum between photons, electrons and ferromagnets. With spin-orbit torque a charge current generates also a spin current to electrically switch the magnetization. This switching determines the spin orientation of injected carriers into semiconductors, in which the transfer of angular momentum from the electron spin to photon controls the circular polarization of the emitted light. The spin-photon conversion with the nonvolatile control of magnetization opens paths to seamlessly integrate information transfer, processing and storage. Our results provide substantial advances towards electrically controlled ultrafast modulation of circular polarization and spin injection with magnetization dynamics for the next-generation information and communication technology, including space-light data transfer. The same operating principle in scaled-down structures or using two-dimensional materials will enable transformative opportunities for quantum information processing with spin-controlled single-photon sources, as well as for implementing spin-dependent time-resolved spectroscopies.

74 ATOMIC AND MOLECULAR PHYSICS↗
NASA NTRS1991

Property and microstructural nonuniformity in the yttrium-barium-copper-oxide superconductor determined from electrical, magnetic, and ultrasonic measurements

The purpose of this dissertation was the following: (1) to characterize the effect of pore fraction on a comprehensive set of electrical and magnetic properties for the yttrium-barium-copper-oxide (YBCO) high temperature ceramic superconductor; and (2) to determine the viability of using a room-temperature, nondestructive characterization method to aid in the prediction of superconducting (cryogenic) properties. The latter involved correlating ultrasonic velocity measurements at room temperature with property-affecting pore fraction and oxygen content variations. The use of ultrasonic velocity for estimating pore fraction in YBCO is presented, and other polycrystalline materials are reviewed, modeled, and statistically analyzed. This provides the basis for using ultrasonic velocity to interrogate microstructure. The effect of pore fraction (0.10-0.25) on superconductor properties of YBCO samples was characterized. Spatial (within-sample) variations in microstructure and superconductor properties were investigated, and the effect of oxygen content on elastic behavior was examined. Experimental methods used included a.c. susceptibility, electrical, and ultrasonic velocity measurements. Superconductor properties measured included transition temperature, magnetic transition width, transport and magnetic critical current density, magnetic shielding, a.c. loss, and sharpness of the voltage-current characteristics. An ultrasonic velocity image constructed from measurements at 1mm increments across a YBCO sample revealed microstructural variations that correlated with variations in magnetic shielding and a.c. loss behavior. Destructive examination using quantitative image analysis revealed pore fraction to be the varying microstructural feature.

Roth, Don J.↗
NASA NTRS1990

CRIT II electric, magnetic, and density measurements within an ionizing neutral stream

Measurements from rocket-borne sensors inside a high-velocity neutral barium beam show a-factor-of-six increase in plasma density in a moving ionizing front. This region was colocated with intense fluctuating electric fields at frequencies well under the lower hybrid frequency for a barium plasma. Large quasi-dc electric and magnetic field fluctuations were also detected with a large component of the current and the electric field parallel to B(0). An Alfven wave with a finite electric field component parallel to the geomagnetic field was observed to propagate along B(0), where it was detected by an instrumented subpayload.

Swenson, C. M.↗
DOE OSTI2024

A novel electro-hydraulic unit design based on a shaftless integration of an internal gear machine and a permanent magnet electric machine

In recent years, increasingly stringent emission regulations have spurred an electrification trend in off-highway vehicle technology. To address challenges such as the high cost of power electronics components, limited battery capacity, and the substantial modifications required for the vehicles, there is a pressing need to develop high-speed, cost-effective, compact, and efficient electro-hydraulic units capable of powering vehicle functions. In response to these demands, this paper introduces an innovative morphology for an electro-hydraulic unit and outlines the integration method for a crescent-type internal gear machine with a permanent magnet synchronous electric machine. The proposed morphology aims to minimize component count through a shaftless solution while incorporating a cooling system that utilizes the same working fluid as the hydraulic machine. The design approach utilizes a genetic algorithm optimization process to maximize overall energy efficiency and compactness. Insights gained from the optimization results shed light on the relationship between key design parameters and unit performance, enhancing the understanding of this electro-hydraulic unit. A prototype of the unit was manufactured and tested, demonstrating a volumetric efficiency ranging from 81 % to 97 % at a maximum rotational velocity of the pinion of 6000 rpm. Finally, these results validate both the morphology and the design approach, indicating the feasibility of designing compact electro-hydraulic units that leverage hydraulic machines with higher maximum rotational velocities than commercially available counterparts as a mean to enhance efficiency and compactness.

30 DIRECT ENERGY CONVERSION↗
NASA NTRS1977

Magnetic electrical connectors for biomedical percutaneous implants

A biomedical percutaneous connector is described which includes a socket having an enlarged disk shaped base portion for being implanted below the patient's skin and cylindrical portion which is integral with the base portion and extends outwardly of the skin. A conical recess in an upper end of the cylindrical portion has a magnet located in the base. Inclined conductive strips are carried on an upper end of the cylindrical portion to which electrical conductors are attached and extend into the patient's body. A complementary shaped plug which also has electrical contacts provided thereon is adapted to fit within the conical recess of the socket. The plug is held in the socket by magnetic force.

Owens, L. J.↗
NASA NTRS1989

Monocoil reciprocating permanent magnet electric machine with self-centering force

A linear reciprocating machine has a tubular outer stator housing a coil, a plunger and an inner stator. The plunger has four axially spaced rings of radially magnetized permanent magnets which cooperate two at a time with the stator to complete first or second opposite magnetic paths. The four rings of magnets and the stators are arranged so that the stroke of the plunger is independent of the axial length of the coil.

Bhate, Suresh K.↗
NASA NTRS2004

"Fan-Tip-Drive" High-Power-Density, Permanent Magnet Electric Motor and Test Rig Designed for a Nonpolluting Aircraft Propulsion Program

A scaled blade-tip-drive test rig was designed at the NASA Glenn Research Center. The rig is a scaled version of a direct-current brushless motor that would be located in the shroud of a thrust fan. This geometry is very attractive since the allowable speed of the armature is approximately the speed of the blade tips (Mach 1 or 1100 ft/s). The magnetic pressure generated in the motor acts over a large area and, thus, produces a large force or torque. This large force multiplied by the large velocity results in a high-power-density motor.

Brown, Gerald V.↗
DOE OSTI2020

Manufacturing Hybrid Copper-Aluminum Rotors for High Power Induction and Permanent Magnet Electric Motors: CRADA 475 [Abstract only]

General Motors Research & Development (GM R&D) and Pacific Northwest National Laboratory (PNNL) will develop an electric rotor manufacturing technology with the potential of making electric motors lighters and more efficient. This will be achieved by developing a solid phase joining method to effectively join the Copper shorting bars to Aluminum end cap.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗