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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

Performance of a Cylindrical Hall-Effect Thruster Using Permanent Magnets

While annular Hall thrusters can operate at high efficiency at kW power levels, it is difficult to construct one that operates over a broad envelope from 1 kW down to 100 W while maintaining an efficiency of 45-55%. Scaling to low power while holding the main dimensionless parameters constant requires a decrease in the thruster channel size and an increase in the magnetic field strength. Increasing the magnetic field becomes technically challenging since the field can saturate the miniaturized inner components of the magnetic circuit and scaling down the magnetic circuit leaves very little room for magnetic pole pieces and heat shields. In addition, the central magnetic pole piece defining the interior wall of the annular channel can experience excessive heat loads in a miniaturized Hall thruster, with the temperature eventually exceeding the Curie temperature of the material and in extreme circumstances leading to accelerated erosion of the channel wall. An alternative approach is to employ a cylindrical Hall thruster (CHT) geometry. Laboratory model CHTs have operated at power levels ranging from 50 W up to 1 kW. These thrusters exhibit performance characteristics that are comparable to conventional, annular Hall thrusters of similar size. Compared to the annular Hall thruster, the CHTs insulator surface area to discharge chamber volume ratio is lower. Consequently, there is the potential for reduced wall losses in the channel of a CHT, and any reduction in wall losses should translate into lower channel heating rates and reduced erosion, making the CHT geometry promising for low-power applications. This potential for high performance in the low-power regime has served as the impetus for research and development efforts aimed at understanding and improving CHT performance. Recently, a 2.6 cm channel diameter permanent magnet CHT (shown in Fig. 1) was tested. This thruster has the promise of reduced power consumption over previous CHT iterations that employed electromagnets. Data are presented to expose the effect different controllable parameters have on the discharge and to summarize performance measurements (thrust, Isp, efficiency) obtained using a thrust stand. In addition, beam current data are presented to show the effect of the magnetic field topology on the plume profile and current utilization and to gain insight into the thruster s operation. These data extend and improve upon the results previously presented by the authors in Ref. [1].

Polzin, Kurt A.↗
DOE OSTI2014

Electroplated L1{sub 0} CoPt thick-film permanent magnets

The fabrication and magnetic characterization of 15-μm-thick electroplated L1{sub 0} CoPt hard magnets with good magnetic properties is reported in this paper. Experimental study of the dependence of the magnets' properties on annealing temperature reveals that an intrinsic coercivity H{sub ci} = ∼800 kA/m (10 kOe), squareness >0.8, and energy product of >150 kJ/m{sup 3} are obtained for photolithographically patterned structures (250 μm × 2 mm stripes; 15 μm thickness) electroplated on silicon substrates and annealed in hydrogen forming gas at 700 °C. Scanning electron microscopy is used to inspect the morphology of both the as-deposited and annealed magnetic layers, and X-ray Diffractometer analysis on the magnets annealed at 700 °C confirm a phase transformation to an ordered L1{sub 0} CoPt structure, with a minor phase of hcp Co. These thick films are intended for microsystems/MEMS applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Magnetic properties and scale-up of nanostructured cobalt carbide permanent magnetic powders

Co{sub x}C magnetic nanoparticles were successfully synthesized via a modified polyol process without using a rare-earth catalyst during the synthesis process. The present results show admixtures of Co{sub 2}C and Co{sub 3}C phases possessing magnetization values exceeding 45 emu/g and coercivity values exceeding 2.3 kOe at room temperature. Moreover, these experiments have illuminated the important role of surfactants, reaction temperature, and reaction duration on the crystallographic structure and magnetic properties of Co{sub x}C, while tetraethylene glycol was employed as a reducing agent. The role of the ratios of Co{sub 2}C and Co{sub 3}C phases in the admixture magnetic properties is discussed. The crystallographic structure and particle size of the Co{sub x}C nanoparticles were characterized by X-ray diffractometry and scanning electron microscopy. Vibrating sample magnetometry was used to determine magnetic properties. Scale-up of synthesis to more than 5 g per batch was demonstrated with no significant degradation of magnetic properties.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

3D printing of anisotropic Sm–Fe–N nylon bonded permanent magnets

Abstract Fabricating a bonded magnet with a near‐net shape in suitable thermoplastic polymer binders is of paramount importance in the development of cost‐effective energy technologies. In this work, anisotropic Sm 2 Fe 17 N 3 (Sm–Fe–N) bonded magnets are additively printed using SmFeN anisotropic magnetic particles in a polymeric binder polyamide‐12 (PA12). The anisotropic SmFeN bonded magnets are fabricated by Big Area Additive Manufacturing followed by post‐printing alignment in a magnetic field. Optimal post‐alignment results in an enhanced remanence of ∼0.68 T in PA12 reflected in a parallel‐oriented (aligned) measured direction. The maximum energy product achieved for the additively printed anisotropic bonded magnet of Sm–Fe–N in PA12 polymer is 78.8 KJ m −3 . Our results show advanced processing flexibility with 3D printing of the development of SmFeN nylon bonded magnets designed for applications with no critical rare earth magnets.

42 ENGINEERING↗
DOE OSTI2012

Profiles of ion beams and plasma parameters on a multi-frequencies microwaves large bore electron cyclotron resonance ion source with permanent magnets

In order to contribute to various applications of plasma and beams based on an electron cyclotron resonance, a new concept on magnetic field with all magnets on plasma production and confinement has been proposed with enhanced efficiency for broad and dense ion beam. The magnetic field configuration consists of a pair of comb-shaped magnet surrounding plasma chamber cylindrically. Resonance zones corresponding for 2.45 GHz and 11-13 GHz frequencies are positioned at spatially different positions. We launch simultaneously multiplex frequencies microwaves operated individually, try to control profiles of the plasma parameters and the extracted ion beams, and to measure them in detail.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

An all permanent magnet electron cyclotron resonance ion source for heavy ion therapy

A high charge state all permanent Electron Cyclotron Resonance ion source, Lanzhou All Permanent ECR ion source no. 3-LAPECR3, has been successfully built at IMP in 2012, which will serve as the ion injector of the Heavy Ion Medical Machine (HIMM) project. As a commercial device, LAPECR3 features a compact structure, small size, and low cost. According to HIMM scenario more than 100 eμA of C{sup 5+} ion beam should be extracted from the ion source, and the beam emittance better than 75 π*mm*mrad. In recent commissioning, about 120 eμA of C{sup 5+} ion beam was got when work gas was CH{sub 4} while about 262 eμA of C{sup 5+} ion beam was obtained when work gas was C{sub 2}H{sub 2} gas. The design and construction of the ion source and its low-energy transportation beam line, and the preliminary commissioning results will be presented in detail in this paper.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Sourcing, Refining and Recycling of Rare-Earth Magnets

Permanent magnets today are used in a wide range of transportation, industrial, residential/commercial, consumer electronics, defense, domestic, data storage, wind energy, and medical markets and applications. There are five classes of commercial permanent magnet materials; however, magnets based on Nd-Fe-B account for over 60% of the global magnet production by value. They typically contain around 31 wt.% of rare earth elements (REEs), principally, Nd and Pr, plus Dy for higher-temperature performance. Nd-Fe-B magnets are forecast to grow throughout this decade, largely driven by the growth in electric vehicles of all types. However, several studies forecast a shortfall of the primary REEs from mined resources. In this paper, the sourcing, processing, and recycling of REEs are discussed. Additionally, presented are the advantages and disadvantages of the major recovery and recycling technologies for REEs.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Tunable Permanent Magnet Quadrupole Operating at Cryogenic Temperatures for Accelerators

The project objective is to develop a compact and tunable quadrupole using Electron Energy Corporation (EEC)’s PM materials for cryogenic accelerator applications. To achieve this objective, EEC and SLAC National Accelerator Laboratory (SLAC) will collaborate to develop a cost-effective quadrupole and optimize the conventional manufacturing process. Based on previous experience, EEC designed an innovative field adjustment capability using tuning magnets which is able to achieve all the requirements for SLAC’s cold copper collider (C3 ) application. These novel ideas enable us to develop a compact and tunable quadrupole magnet superior to the current designs. Our approach is to leverage EEC's over 50 years of experience in magnet manufacturing and SLAC’s beamline test capabilities.

42 ENGINEERING↗
DOE OSTI2016

High performance Nd-Fe-B permanent magnets without critical elements

Scanning electron microscopy, and magnetization measurements reveal that as cast (Nd 1–x Ce x ) 2 Fe 14 B alloys contain significant amounts of α-Fe that can be dramatically reduced by annealing the alloys at 1000 °C for 3 days. The room temperature intrinsic coercivity, Hci, of (Nd 0.8 Ce 0.2 ) 2.2 Fe 14 B melt spun ribbons was found to be 11 kOe, which is ~32 to ~10% higher in comparison to that of Nd 2 Fe 14 B (Hci = 8.3 kOe), and (Nd 0.8 Ce 0.2 ) 2.0 Fe 14 B (Hci = 10 kOe), respectively. The substitution of Co for Fe in (Nd 0.8 Ce 0.2 ) 2 Fe 14–z Co z B significantly increases both TC and the maximum energy product, (BH)max. Our study shows that both Co-containing and Co-free Ce-substituted Nd 2 Fe 14 B alloys have excellent magnetic properties at room temperature and above. As a result, the experimental results also demonstrate the potential of Nd-Ce-Fe-TM-B based alloys as alternative to expensive Dy-containing high performance rare earth magnets.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Cu substituted CeCo 5 : New optimal permanent magnetic material with reduced criticality

A comprehensive theoretical prediction using a mechanism of site substitution confirms the crucial role of Cu in enhancing the capabilities of CeCo 5 as a competitive magnet with its known high coercivity. A remarkable enhancement of magnetic anisotropy energy (MAE) of 3.09 meV/f.u. and 2.94 meV/f.u. without significant decrease of magnetic moment is found for 10% and 5% Cu substitution at 2c sites of the hexagonal lattice. Our calculations predict the increment of coercivity and magnetocrystalline anisotropy (1.6 times) compared to pristine CeCo 5 . Furthermore, the exceptional enhancement in MAE is due to the formation of asymmetric charge hybridization among the Cu (2c) and Co (both 2c and 3g) sites along the uniaxial direction. Because of this asymmetric charge distribution environment, the intrinsic behavior of Ce adjacent to Cu changes abruptly making them more uniaxial and magnetically enhanced creating mixed valence states. For our calculations, we have employed the full-potential augmented plane wave method in conjunction with spin orbit coupling.

36 MATERIALS SCIENCE↗
DOE OSTI2016

A supported liquid membrane system for the selective recovery of rare earth elements from neodymium-based permanent magnets

We present that the rare earth elements (REEs) play a vital role in the development of green energy and high-tech industries. In order to meet the fast-growing demand and to ensure sufficient supply of the REEs, it is essential to develop an efficient REE recovery process from post-consumer REE-containing products. In this research effort, we have developed a supported liquid membrane system utilizing polymeric hollow fiber modules to extract REEs from neodymium-based magnets with neutral extractants such as tetraoctyl digylcol amide (TODGA). The effect of process variables such as REE concentration, molar concentration of acid, and membrane area on REE recovery was investigated. We have demonstrated the selective extraction and recovery of REEs such as Nd, Pr, and Dy without co-extraction of non-REEs from permanent NdFeB magnets through the supported liquid membrane system. The extracted REEs were then recovered by precipitation followed by the annealing step to obtain crystalline REE powders in nearly pure form. Finally, the recovered REE oxides were characterized by X-ray diffraction, scanning electron microscope coupled with energy-dispersive X-ray spectroscopy, and inductively coupled plasma–optical emission spectroscopy.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Permanent-magnet Faraday isolator with the field intensity of 25 kOe

A Faraday isolator with a single magneto-optical element is constructed and experimentally tested. It provides the isolation ratio of 30 dB at an average laser radiation power of 650 W. These parameters are obtained by increasing the field intensity in the magnetic system of the isolator and employing a low-absorption magneto-optical element. (elements of laser devices)

74 ATOMIC AND MOLECULAR PHYSICS↗