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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Design and construction of the MUSE permanent magnet stellarator

This paper documents the design and construction of MUSE, the world's first permanent magnet (PM) stellarator and the first quasi-axisymmetric experiment. The purpose of MUSE is to develop and assess a new way of building optimised stellarators that uses simple planar coils PMs. Our PM optimisation algorithm consists of initialising a geometry to pack dipoles densely, running the FAMUS code to minimise surface field error subject to PM constraints and applying discrete jumps to reach a physically realisable solution. FAMUS treats the PM system as a set of ideal point dipoles. From there we construct finite-volume magnet towers to be housed in 3D-printed PM holders. We describe the design of the PM holders, which were validated by laser metrology. We analyse the effects of finite permeability, sensitivity to perturbations and magnetostatic forces. An exact analytic formula for the magnetic field from a finite-volume PM tower is presented to compute PM–PM forces and stress on the PM holder. Stellarator construction is complete and experiments are underway.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Jump-Start U.S. Manufacturing of High-Performance Permanent Magnets

Gas atomized feedstock powders for Nd-Fe-B based magnets are more robust and cost effective than the strip-cast sheet currently used as feedstock for milling by the magnet industry. However, gas atomized powder’s crystallinity and grain boundary phases are less ideal than the strip cast flake. We proposed to optimize the atomization process as well as the powder chemistry to address this issue and to eliminate heavy rare earth elements from these magnet alloys. Our goal is to help GKN-Hoeganaes, a US metal powder company, who used to make Nd-Fe-B magnets, to bring back US manufacturing of these high energy density permanent magnets.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Binder-free cold spray deposition of NdFeB permanent magnets

Cold spray deposition is employed to manufacture binder-free Nd 2 Fe 14 B permanent magnets. Millimeter thick deposits can be fabricated in seconds on substrates such as glass or copper. The Nd 2 Fe 14 B particles appear to partially embed in the substrate and interlock with one another, building up a dense layer that is consolidated by subsequent impacts. The impact and subsequent heating of the particles leads to formation of a magnetically soft phase that significantly reduces coercivity, X-ray diffraction identifies it as Fe. Furthermore, this can be mitigated by reducing gas velocity and temperature, leading to a partial retention of magnetic properties.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Laminated Permanent Magnets Enable Compact Magnetic Components in Current-Source Converters

Magnetic components have become one of the primary barriers to high power density converters, especially to current-source converters (CSCs). In CSCs, the inductors/transformers have a predominantly dc flux to store energy, which can be offset by standard permanent magnets (PMs). However, eddy currents in standard PMs induce significant losses and thermal stress for medium-frequency applications. This article proposes using laminated PMs to offset the dc flux while reducing eddy currents, leading to significant reductions in the size, cost, and losses of inductors/transformers. Furthermore, the laminated PMs’ optimal location, orientation, and distribution are investigated to generalize this approach for maximum benefits. Here, three-dimensional finite-element analysis simulation and hardware experiments are presented to validate the effectiveness of the proposed approach in a medium-frequency transformer (MFT) for CSCs. Compared with standard PMs, the proposed use of laminated PMs reduces aggregate core-plus-PM losses by 85% in experiments, and thus, relaxes the MFT thermal design. Finally, the proposed approach is experimentally validated in a 40 kVA flyback-type MFT for a soft-switching solid-state transformer. Compared to the traditional design without any PMs, the proposed design increases the saturation current by 46% while inducing only 5% more losses, leading to significant savings in magnetics cost and size.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2020

Permanent magnets for the return loop of the Cornell-Brookhaven energy recovery linac test accelerator

214 neodymium permanent magnets have been manufactured for the return loop of the CBETA multi-turn ERL at Cornell University. There are 5 types of quadrupole and combined-function gradient magnets using a variant of the circular Halbach design. These are made out of NdFeB material and glued into an aluminium housing with water channels for temperature stabilisation. The NdFeB wedges and magnet construction were done by outside companies, while the final “tuning” using inserts containing 64 iron rods per magnet was done at BNL over a period of about 6 months. Average relative field errors of 2.2×10 -4 were achieved on the beam region. The magnet strengths vary by type but are of order 10 T/m for quadrupole component and up to 0.3 T for the dipole. This paper reports on the field quality and timeline achieved in this production process

43 PARTICLE ACCELERATORS↗
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↗
DOE OSTI2020

Cost Estimation of a Permanent Magnet Synchronous Machine for Use in Adjustable Speed-Pumped Storage Hydropower

Electric machine design has become an easier process with the availability of computers in recent decades. However, the interest in electric machine design among students has declined. University-level design courses must compete with courses perceived as more desirable by the potential job market. Hence, the power system engineers with this expertise are very few and are nearing retirement. Contrarily, renewable energy has been picking up in the past few decades. The indeterminacy and variation of renewable energy sources require a balancing mechanism to maintain the constant voltage and frequency of the grid. Adjustable-Speed Pumped-Storage Hydropower plants are considered the contender for future energy storage, providing large capacity and fast-acting response. Large-scale hydropower applications depend on the natural characteristics of each project site, making less expensive, off-the-shelf generators unfeasible. This work gives a shortcut to estimate the cost of constructing a permanent magnet generator for low-volume manufacturing.

13 HYDRO ENERGY↗
DOE OSTI2025

Solenoidal Fields from Permanent Magnets for a Polarized Electron Preinjector

This technical note describes the design of a compact focusing solenoid constructed from permanent bar magnets, intended for the low-energy section of a spin-polarized electron injector. Typically, quadrupole triplets provide appropriate focusing for the low-energy spin rotator section; however, their large footprint precludes the insertion of sufficient beam diagnostics. The primary motivation of this study is to provide beam focusing while preserving the vertical spin orientation of the electron beam. We propose a solenoidal field composed of multiple permanent magnets arranged to naturally yield a zero longitudinal magnetic field integral ($\int B_zdz = 0$). This design serves as a compact, passive, and non-coupling alternative to traditional quadrupole triplets. We present the magnet arrangement, field calculation methodology, spin tracking simulations using space charge codes, and calculations demonstrating that the required field strength is achievable.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Extended State Observer-Based Robust Model Predictive Velocity Control for Permanent Magnet Synchronous Motor

This article proposes an extended state observer based robust model predictive velocity control to decrease system prediction error under parameter uncertainties for permanent magnet synchronous motor (PMSM). We develop a new PMSM model that consists of velocity and acceleration to lump the system information and an external disturbance into a disturbance. The extended state observer (ESO) is designed to estimate the velocity, acceleration, and disturbance. By estimating the state variables and disturbance using the ESO, the model predictive control (MPC) finds the optimal control input by predicting future system behavior. Additionally, the direct current controller is designed so that the direct current converges to zero. Because the proposed method is not designed based on the cascade structure from the viewpoint of velocity control, the optimization control for the velocity and currents can be defined. Thus, the proposed method is robust against external disturbances and parameter uncertainties owing to feedback linearization, state feedback, and ESO-based MPC using the acceleration PMSM model. The proposed control algorithm was experimentally verified and it showed improved velocity tracking performance compared with ESO-based MPC using the conventional PMSM model.

42 ENGINEERING↗
DOE OSTI2025

Assessment of errors in analytic modeling of permanent magnet electron spectrometers for laser-plasma accelerators

Here, we assess the error in three treatments of a critical electron beam diagnostic for laser-plasma acceleration (LPA) experiments: a permanent magnet electron spectrometer. Since LPA electron spectrometers are often difficult to calibrate due to the scarcity of well-characterized, tunable electron beam sources in the appropriate energy range and the mechanical complexity of electron spectrometers, the standard of calibration is Hall probe measurements. We first compare the electron spectrometer performance between SIMION calculations and the Hall probe measurements. We find up to a 60% (<8%) error in determining the absolute energy for electrons below (above) 80 MeV when using the SIMION-modeled magnetic field vs the measured magnetic field due to SIMION overpredicting fringe field strength. The difference in spectrometer energy resolution is within ∼10% between the modeled and measured fields. We then assess a simple block model, which is commonly used. We find that the simple block model presented here sufficiently captures the predicted as-built spectrometer performance for any application provided that the user can tolerate uncertainties on absolute energy determination up to 5% and errors on energy resolution up to 1%.

Electromagnetic optics↗
DOE OSTI2022

Solvent-driven fractional crystallization for atom-efficient separation of metal salts from permanent magnet leachates

Abstract This work reports a dimethyl ether-driven fractional crystallization process for separating rare earth elements and transition metals. The process has been successfully applied in the treatment of rare earth element-bearing permanent magnet leachates as an atom-efficient, reagent-free separation method. Using ~5 bar pressure, the solvent was dissolved into the aqueous system to displace the contained metal salts as solid precipitates. Treatments at distinct temperatures ranging from 20–31 °C enable crystallization of either lanthanide-rich or transition metal-rich products, with single-stage solute recovery of up to 95.9% and a separation factor as high as 704. Separation factors increase with solution purity, suggesting feasibility for eco-friendly solution treatments in series and parallel to purify aqueous material streams. Staged treatments are demonstrated as capable of further improving the separation factor and purity of crystallized products. Upon completion of a crystallization, the solvent can be recovered with high efficiency at ambient pressure. This separation process involves low energy and reagent requirements and does not contribute to waste generation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Permanently Magnetized Insulating Thin-Film Devices by Reduction

A reduction-based manufacturing process for creating technologically important multilayer structures from lattice-matched ferromagnetic insulators and ferromagnetic conductors is reported. The process is demonstrated by growing a permanently magnetized double-layer structure, consisting of lattice-matched conducting (Ni,Co) and insulating (Ni 0.4 Co 0.6 ) 3 O 3 layers, through a single deposition cycle. The orientation of the metal cation network is preserved after reduction. Close-packing displacements of Ni and Co take place in such a manner that the in-plane hexagonal arrangement is preserved. This is critical for ensuring high-quality interfaces joining the layers. At room temperature the hysteresis loop is centered. At low temperature the oxide layer becomes ferrimagnetically ordered, accompanied by a shift of the hysteresis loop along the magnetic field axis. The shift is assigned to exchange bias phenomenon. Biaxial compressive strain is responsible for the required ferrimagnetic ordering. Finally, spin valves and closely related magnetoresistance random access memory and spin-transfer-torque magnetic random access memory devices are addressed as potential applications.

42 ENGINEERING↗
DOE OSTI2026

Design and optimization of processes for recovering rare earth elements from end‐of‐life permanent magnets

Recovery of rare earth elements (REEs) from end-of-life (EOL) products represents a strategic opportunity to strengthen the domestic supply chain for rare earth elements. This work presents a superstructure-based optimization framework for finding the most economical processing pathway for different EOL rare earth permanent magnets (REPMs). The framework evaluates state-of-the-art technologies across four processing stages—disassembly, demagnetization, leaching and extraction, and precipitation and calcination—using net present value (NPV) maximization and cost of recovery (COR) minimization objectives. A novel bottom-up costing framework for hydrogen decrepitation is also introduced. Two feedstocks were considered: REPMs from EOL hard disk drives (HDDs), and electric and hybrid electric vehicles (EVs and HEVs). While HDD recycling proved unprofitable due to limited feedstock availability, EVs/HEVs were profitable across a range of parameters and cost estimates. Therefore, our findings suggest that the proposed EOL EV/HEV recycling process may be economical and is worthy of further investigation.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2024

Field Harmonic Measurement of High-Gradient Permanent Magnet Quadrupoles for NSLS- II Upgrade

The National Synchrotron Light Source II (NSLS-II) is preparing for a major upgrade based on a new lattice concept, known as “Complex Bend,” to replace its existing double bend achromat (DBA) lattice. Here, this novel lattice will use high-gradient permanent magnet quadrupoles (PMQs) with small apertures in the range of 16–22 mm. A prototype complex bend branch with PMQs has been installed in the NSLS-II linac to evaluate the lattice's performance. An accurate and precise magnetic measurement system is required for field harmonic characterization and magnetic tuning of these PMQs. As part of this project a Rotating-Coil bench, based on a Printed Circuit Board (PCB) coil with a 12 mm diameter, has been configured to measure nine PMQs with bore diameter of 12.7 mm. This PCB coil has an active length of 270 mm, and is able to measure fields up to the 15th harmonic of the main field at a reference radius of 5 mm, while maintaining field quality levels within 10 ppm of the main field. This article presents the PCB coil setup, the harmonic measurement results and their temperature dependencies and repeatability. Simulation results on compensation of undesired multipoles using “IDBuilder”, a genetic algorithm-based optimizer code for magnetic tuning is included for field harmonic corrections.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Magnetic feed material and its use in producing bonded permanent magnets by additive manufacturing

A method for producing magnet-polymer pellets useful as a feedstock in an additive manufacturing process, comprising: (i) blending thermoplastic polymer and hard magnetic particles; (ii) feeding the blended magnet-polymer mixture into a pre-feed hopper that feeds directly into an inlet of a temperature-controlled barrel extruder; (iii) feeding the blended magnet-polymer mixture into the barrel extruder at a fixed feed rate of 5-20 kg/hour, wherein the temperature at the outlet is at least to no more than 10° C. above a glass transition temperature of the blended magnet-polymer mixture; (iv) feeding the blended magnet-polymer mixture directly into an extruding die; (v) passing the blended magnet-polymer mixture through the extruding die at a fixed speed; and (vi) cutting the magnet-polymer mixture at regular intervals as the mixture exits the extruding die at the fixed speed. The use of the pellets as feed material in an additive manufacturing process is also described.

36 MATERIALS SCIENCE↗
DOE OSTI2020

A Comprehensive Review of Permanent Magnet Transverse Flux Machines: Use in Direct-Drive Applications

The use of direct-drive machines in renewable and industrial applications is increasing at a rapid rate. Transverse flux machines (TFMs) are ideally suited for direct-drive applications due to their high torque density. This article presents a comprehensive review of permanent magnet (PM) TFMs for direct-drive applications. It introduces TFMs and their operating principle and reviews the different types of TFMs proposed in the literature. TFMs are categorized by the number of stator sides, types of stator cores, and magnet arrangement in the rotor. The review covers different design topologies, materials used for manufacturing, structural and thermal analyses, modeling, design optimization, and cogging torque minimization in TFMs. The article also examines various applications and comparisons for TFMs presented in the literature.

air gaps↗
DOE OSTI2024

Injection, confinement, and diagnosis of electrons and positrons in a permanent magnet dipole trap

Abstract Prerequisites for the goal of studying long-lived, magnetically confined, electron–positron pair plasmas in the laboratory include the injection of both species into the trap, long trapping times, and suitable diagnostic methods. Here we report recent progress on these tasks achieved in a simple dipole trap based on a supported permanent magnet. For the injection of electrons, both an $$\textbf{E}\times B$$ E × B drift technique (of a $$\sim $$ ∼ 2– $$\upmu $$ μ A, 6-eV beam) and “edge injection” (from a filament emitting a few mA and biased to some tens of volts) have been demonstrated; the former is suitable for low-density beams with smaller spatial and velocity spreads, while the latter employs fluctuations arising from collective behavior. To diagnose the edge-injected electrons, image potentials and currents induced on a wall probe, the magnet case, and wall electrodes were measured. Confinement of drift-injected positrons, measured experimentally, exhibited at least two well-separated timescales. Simulations reproduced this qualitatively, using a simple model of elastic collisions with residual background gas, and point to small adjustments for increasing trapping times. In a major upgrade to diagnostic capabilities, 25 bismuth germanate detectors, placed in three reentrant ports, are able to localize annihilation gammas, which will be used in future experiments to distinguish between different loss channels. Graphical abstract

von der Linden, J. (ORCID:0000000327477813)↗