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Sample records for high-temperature permanent magnets

  1. Permanent magnets composed of high temperature superconductors

    Science.gov (United States)

    Weinstein, Roy; Chen, In-Gann; Liu, Jay; Lau, Kwong

    1991-01-01

    A study of persistent, trapped magnetic field has been pursued with high-temperature superconducting (HTS) materials. The main effort is to study the feasibility of utilization of HTS to fabricate magnets for various devices. The trapped field, when not in saturation, is proportional to the applied field. Thus, it should be possible to replicate complicated field configurations with melt-textured YBa2Cu3O7 (MT-Y123) material, bypassing the need for HTS wires. Presently, materials have been developed from which magnets of 1.5 T, at 77 K, can be fabricated. Much higher field is available at lower operating temperature. Stability of a few percent per year is readily attainable. Results of studies on prototype motors and minimagnets are reported.

  2. Accelerated Testing of High Temperature Permanent Magnets for Spacecraft Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High temperature permanent magnet materials play an important role in NASA's space missions in electric propulsion, energy generation and storage and other...

  3. High Temperature, Permanent Magnet Biased, Fault Tolerant, Homopolar Magnetic Bearing Development

    Science.gov (United States)

    Palazzolo, Alan; Tucker, Randall; Kenny, Andrew; Kang, Kyung-Dae; Ghandi, Varun; Liu, Jinfang; Choi, Heeju; Provenza, Andrew

    2008-01-01

    This paper summarizes the development of a magnetic bearing designed to operate at 1,000 F. A novel feature of this high temperature magnetic bearing is its homopolar construction which incorporates state of the art high temperature, 1,000 F, permanent magnets. A second feature is its fault tolerance capability which provides the desired control forces with over one-half of the coils failed. The construction and design methodology of the bearing is outlined and test results are shown. The agreement between a 3D finite element, magnetic field based prediction for force is shown to be in good agreement with predictions at room and high temperature. A 5 axis test rig will be complete soon to provide a means to test the magnetic bearings at high temperature and speed.

  4. The Behavior Of Asymmetric Frontal Couplings With Permanent Magnets In Magnetic Powder And High Temperature Environments

    Directory of Open Access Journals (Sweden)

    Ion DOBROTA

    2002-12-01

    Full Text Available The main purpose of this paper is the comparative analysis of the behavior of frontal couplings with Nd-Fe-B permanent magnets in difficult environments, specific to metallurgy – such as environments with magnetic powders and high temperature – in two constructive variants: symmetric couplings and asymmetric couplings (with divided poles. The results show the superior performance of asymmetric couplings under the given conditions

  5. Measuring the interaction force between a high temperature superconductor and a permanent magnet

    OpenAIRE

    Valenzuela, S. O.; Jorge, G. A.; Rodriguez, E.

    1999-01-01

    Repulsive and attractive forces are both possible between a superconducting sample and a permanent magnet, and they can give place to magnetic levitation or free-suspension phenomena, respectively. We show experiments to quantify this magnetic interaction which represents a promising field regarding to short-term technological applications of high temperature superconductors. The measuring technique employs an electronic balance and a rare-earth magnet that induces a magnetic moment in a melt...

  6. Stable levitation of steel rotors using permanent magnets and high-temperature superconductors

    Science.gov (United States)

    Hull, J. R.; Passmore, J. L.; Mulcahy, T. M.; Rossing, T. D.

    1994-07-01

    Individual freely spinning magnetic steel rotors were levitated by combining the attractive force between permanent magnets and the rotor with the repulsive force between high-temperature superconductors and the steel. The levitation force and stiffness of several configurations are presented, and the application of this levitation method to high-speed bearings is discussed.

  7. A nanocrystalline Sm-Co compound for high-temperature permanent magnets.

    Science.gov (United States)

    Zhang, Zhexu; Song, Xiaoyan; Qiao, Yinkai; Xu, Wenwu; Zhang, Jiuxing; Seyring, Martin; Rettenmayr, Markus

    2013-03-21

    The inherently high magnetic anisotropy and nanoscale grain size in a Sm5Co19 compound result in an intrinsic coercivity far higher than those of known Sm-Co compounds prior to orientation treatment. The combination of ultrahigh intrinsic coercivity, high Curie temperature and low coercivity temperature coefficient of nanocrystalline Sm5Co19 as a single phase material shows it to be a very promising compound to develop outstanding high-temperature permanent magnets.

  8. Measuring the interaction force between a high temperature superconductor and a permanent magnet

    Science.gov (United States)

    Valenzuela, S. O.; Jorge, G. A.; Rodríguez, E.

    1999-11-01

    Repulsive and attractive forces are both possible between a superconducting sample and a permanent magnet, and they can give rise to magnetic levitation or free-suspension phenomena, respectively. We show experiments to quantify this magnetic interaction, which represents a promising field with regard to short-term technological applications of high temperature superconductors. The measuring technique employs an electronic balance and a rare-earth magnet that induces a magnetic moment in a melt-textured YBa2Cu3O7 superconductor immersed in liquid nitrogen. The simple design of the experiments allows a fast and easy implementation in the advanced physics laboratory with a minimum cost. Actual levitation and suspension demonstrations can be done simultaneously as a help to interpret magnetic force measurements.

  9. Makeup and uses of a basic magnet laboratory for characterizing high-temperature permanent magnets

    Science.gov (United States)

    Niedra, Janis M.; Schwarze, Gene E.

    1991-01-01

    A set of instrumentation for making basic magnetic measurements was assembled in order to characterize high intrinsic coercivity, rare earth permanent magnets with respect to short term demagnetization resistance and long term aging at temperatures up to 300 C. The major specialized components of this set consist of a 13 T peak field, capacitor discharge pulse magnetizer; a 10 in. pole size, variable gap electromagnet; a temperature controlled oven equipped with iron cobalt pole piece extensions and a removable paddle that carries the magnetization and field sensing coils; associated electronic integrators; and sensor standards for field intensity H and magnetic moment M calibration. A 1 cm cubic magnet sample, carried by the paddle, fits snugly between the pole piece extensions within the electrically heated aluminum oven, where fields up to 3.2 T can be applied by the electromagnet at temperatures up to 300 C. A sample set of demagnetization data for the high energy Sm2Co17 type of magnet is given for temperatures up to 300 C. These data are reduced to the temperature dependence of the M-H knee field and of the field for a given magnetic induction swing, and they are interpreted to show the limits of safe operation.

  10. Vertical and lateral forces between a permanent magnet and a high-temperature superconductor

    Science.gov (United States)

    Hull, John R.; Cansiz, Ahmet

    1999-12-01

    The vertical and horizontal forces and associated stiffnesses on a permanent magnet (PM) above a high-temperature superconductor (HTS) were measured during vertical and horizontal traverses in zero-field cooling (ZFC) and in field cooling (FC). In ZFC, the vertical stiffness was greater in the first descent than in the first ascent and second descent, and the stiffness in the second descent was between those of the first descent and the first ascent. At the FC position, the vertical stiffness was two times greater than the lateral stiffness at each height, to within 1% of the vertical stiffness value. The cross stiffness of vertical force with respect to lateral position was positive for FC, but negative for ZFC. Free-spin-down experiments of a PM levitated above a HTS were also performed. These results showed that the coefficient of friction is double valued at frequencies just below the rotor resonance, a result attributed to cross stiffness in the PM/HTS interaction. A frozen-image model was used to calculate the vertical and horizontal forces and stiffnesses, and reasonable agreement with the data occurred for vertical or horizontal movements of the PM less than several mm from the FC position.

  11. COMPARATIVE ANALYSIS OF THE BEHAVIOR OF COAXIAL AND FRONTAL COUPLINGS – WITH PERMANENT MAGNETS – IN HIGH TEMPERATURE ENVIRONMENTS

    Directory of Open Access Journals (Sweden)

    Marcel Oanca

    2004-12-01

    Full Text Available This paper presents a comparative analysis of the behavior of coaxial and frontal couplings – with permanent magnets – in high temperature environments specific to iron and steel industry. The comparative analysis is made at the level of the specific forces developed in the most difficult environments. The maximum temperature was limited for reasons of thermal stability of the Nd-Fe-B permanent magnets. In this context it was studied, by the help of the PDE-ase soft that uses the finite element method, the way magnetic induction modifies, the specific forces developed and the distribution of temperature within the coaxial and frontal couplers with permanent magnets, for variations of the distance between the magnets (air gap within the limits 2-20 mm.

  12. Magnetic levitation performance of high-temperature superconductor over three magnetic hills of permanent magnet guideway with iron shims of different thicknesses

    Institute of Scientific and Technical Information of China (English)

    Yuming Gong; Gang Liang; Lifeng Zhao; Yong Zhang; Yong Zhao; Xuyong Chen

    2014-01-01

    Superconducting magnetic levitation perfor-mance, including levitation force and guidance force, is important for the application of high-temperature super-conducting maglev. Both of them are not only affected by different arrays of superconductors and magnets, but also by the thickness of the iron shim between permanent magnets. In order to obtain the best levitation performance, the magnetic field distribution, levitation force, and guid-ance force of a new type of three magnetic hills of per-manent magnet guideway with iron shim of different thicknesses (4, 6, and 8 mm) are discussed in this paper. Simulation analysis and experiment results show that the guideway with iron shim of 8 mm thickness possesses the strongest magnetic field and levitation performance when the suspension gap is larger than 10 mm. However, with the decreasing of suspension gap, the guideway with iron shim of 4 mm thickness possesses the best levitation per-formance. The phenomena can be attributed to the density distribution of flux and magnetization of iron shim.

  13. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed electromagnets only. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

  14. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed only electromagnets. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

  15. Dynamic response characteristics of high temperature superconducting maglev systems: Comparison between Halbach-type and normal permanent magnet guideways

    Energy Technology Data Exchange (ETDEWEB)

    Wang, B. [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); Zheng, J., E-mail: jzheng@swjtu.cn [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); Che, T. [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); Zheng, B.T.; Si, S.S. [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, P R China (China); Deng, Z.G., E-mail: deng@swjtu.cn [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China)

    2015-12-15

    Highlights: • The loading weight affects the RF tremendously. • Reducing the FCH can improve the stability of the maglev vehicle. • The Halbach-type PMG has better loading capacity than the conventional PMG. • Pre-load is an effective way to enhance the dynamic characteristic of the HTS maglev vehicle. - Abstract: The permanent magnet guideway (PMG) is very important for the performance of the high temperature superconducting (HTS) system in terms of electromagnetic force and operational stability. The dynamic response characteristics of a HTS maglev model levitating on two types of PMG, which are the normal PMG with iron flux concentration and Halbach-type PMG, were investigated by experiments. The dynamic signals for different field-cooling heights (FCHs) and loading/unloading processes were acquired and analyzed by a vibration analyzer and laser displacement sensors. The resonant frequency, stiffness and levitation height of the model were discussed. It was found that the maglev model on the Halbach-type PMG has higher resonant frequency and higher vertical stiffness compared with the normal PMG. However, the low lateral stiffness of the model on the Halbach-type PMG indicates poor lateral stability. Besides, the Halbach-type PMG has better loading capacity than the normal PMG. These results are helpful to design a suitable PMG for the HTS system in practical applications.

  16. Rare earth permanent-magnet alloys’ high temperature phase transformation in situ and dynamic observation and its application in material design

    CERN Document Server

    Pan, Shuming

    2013-01-01

    The process of high temperature phase transition of rare earth permanent-magnet alloys is revealed by photographs taken by high voltage TEM. The relationship between the formation of nanocrystal and magnetic properties is discussed in detail, which effects alloys composition and preparation process. The experiment results verified some presumptions, and were valuable for subsequent scientific research and creating new permanent-magnet alloys. The publication is intended for researchers, engineers and managers in the field of material science, metallurgy, and physics. Prof. Shuming Pan is senior engineer of Beijing General Research Institute of Non-ferrous Metal.

  17. Studies on Magnetization Technique of High Temperature Superconductors

    OpenAIRE

    大橋, 忠巌; 荻原, 宏康

    1999-01-01

    It is known that permanent magnets produce magnetic fields up to 1T. On the other hand, magnetized high temperature superconductors can be used as "super"-permanent magnets which produce magnetic fields higher than 1T, because superconductors can trap higher magnetic fluxes than usual permanent magnets. In order to magnetize a YBCO bulk superconductor, there are two ways; a field cooling (FC) method and a zero field cooling (ZFC) method. FC is the way of magnetizing the superconductor by appl...

  18. High temperature superconductor accelerator magnets

    NARCIS (Netherlands)

    van Nugteren, J.

    2016-01-01

    For future particle accelerators bending dipoles are considered with magnetic fields exceeding 20T. This can only be achieved using high temperature superconductors (HTS). These exhibit different properties from classical low temperature superconductors and still require significant research and dev

  19. Development and testing of a 2.5 kW synchronous generator with a high temperature superconducting stator and permanent magnet rotor

    Science.gov (United States)

    Qu, Timing; Song, Peng; Yu, Xiaoyu; Gu, Chen; Li, Longnian; Li, Xiaohang; Wang, Dewen; Hu, Boping; Chen, Duxing; Zeng, Pan; Han, Zhenghe

    2014-04-01

    High temperature superconducting (HTS) armature windings have the potential for increasing the electric loading of a synchronous generator due to their high current transport capacity, which could increase the power density of an HTS rotating machine. In this work, a novel synchronous generator prototype with an HTS stator and permanent magnet rotor has been developed. It has a basic structure of four poles and six slots. The armature winding was constructed from six double-pancake race-track coils with 44 turns each. It was designed to deliver 2.5 kW at 300 rpm. A concentrated winding configuration was proposed, to prevent interference at the ends of adjacent HTS coils. The HTS stator was pressure mounted into a hollow Dewar cooled with liquid nitrogen. The whole stator could be cooled down to around 82 K by conduction cooling. In the preliminary testing, the machine worked properly and could deliver 1.8 kW power when the armature current was 14.4 A. Ic for the HTS coils was found to be suppressed due to the influence of the temperature and the leakage field.

  20. 1998 Annual Study Report. Research and development of power storage by high-temperature superconducting flywheels (research and development of permanent magnet); 1998 nendo seika hokokusho. Koon chodendo flywheel denryoku chozo kenkyu kaihatsu (eikyu jishaku no kenkyu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-05-01

    The permanent magnets have been investigated and developed, for eventual commercialization of a 10 MWh power storage system by high-temperature superconducting flywheel. The permanent magnet rotors have been already developed in the previous years using a praseodymium-based magnet (Pr magnet) and neodymium-based sintered magnet (Nd sintered magnet), and the target rotational speed of 30,000 rpm has been attained. For development of the magnetic circuit to produce a stronger and smoother magnetic field, magnetic flux density of the Nd sintered magnet is measured. It shows a lower magnetic flux irregularity than the Pd magnet, but there is still room for further improvement. For development of large-size permanent magnet fabrication techniques, it is confirmed that the large-size Nd sintered magnet can be easily magnetized by partial magnetizing, as is the case with the Pr magnet. In this year, the irregular magnetic flux is three-dimensionally simulated, based on the results obtained in the previous years, to find that the simulated results are in good agreement with the observed ones. The measures to solve the problems are also investigated. It is also confirmed that the large-size ring magnet can be easily magnetized by partial magnetization. (NEDO)

  1. High Temperature Superconductor Accelerator Magnets

    CERN Document Server

    AUTHOR|(CDS)2079328; de Rijk, Gijs; Dhalle, Marc

    2016-11-10

    For future particle accelerators bending dipoles are considered with magnetic fields exceeding $20T$. This can only be achieved using high temperature superconductors (HTS). These exhibit different properties from classical low temperature superconductors and still require significant research and development before they can be applied in a practical accelerator magnet. In order to study HTS in detail, a five tesla demonstrator magnet named Feather-M2 is designed and constructed. The magnet is based on ReBCO coated conductor, which is assembled into a $10kA$ class Roebel cable. A new and optimized Aligned Block layout is used, which takes advantage of the anisotropy of the conductor. This is achieved by providing local alignment of the Roebel cable in the coil windings with the magnetic field lines. A new Network Model capable of analyzing transient electro-magnetic and thermal phenomena in coated conductor cables and coils is developed. This model is necessary to solve critical issues in coated conductor ac...

  2. Permanent magnet design for high-speed superconducting bearings

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (5519 S. Bruner, Hinsdale, IL 60521); Uherka, Kenneth L. (830 Ironwood, Frankfort, IL 60423); Abdoud, Robert G. (13 Country Oaks La., Barrington Hills, IL 60010)

    1996-01-01

    A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing.

  3. MHD-, ships-, jet engine unit consisting of electrochemical cells producing hydrogen, magneto-caloric hydrogen liquefier, liquid hydrogen-cooled high temperature superconductor-, MHD-, jet engine, liquid hydrogen internal combustion engine as high temperature-, superconductor-, generator-drive. High temperature superconductor coil and permanent magnet superconductor hollow cylinder as battery. MHD-Schiffs-Strahltriebwerks-Aggregat bestehend aus Wasserstoff-produzierenden elektrochemischen Solarzellen, magnetokalorischem Wasserstoffverfluessiger, Fluessigwasserstoff gekuehltem Hochtemperatur-Supraleiter-MHD-Strahltriebwerk, Fluessigwasserstoff-Verbrennungsmotor als Hochtemperatur-Supraleiter-Generator-Antrieb, Hochtemperatur-Supraleiter-Spule und permanentmagnetischem Supraleiter-Hohlzylinder als Akku

    Energy Technology Data Exchange (ETDEWEB)

    Berling, E.

    1991-05-02

    MHD-, ships-, jet engine-unit consisting of electrochemical cells producing hydrogen, magneto-caloric hydrogen liquifier, liquid hydrogen-cooled high temperature superconductor-, MHD-, jet engine, liquid hydrogen internal combustion engine as high temperature-, superconductor-, generator-drive. High temperature superconductor coil and permanent magnet superconductor hollow cylinder as battery. Ships water jet engines with magneto hydrodynamic (MHD) low temperature superconductor drive are known. The invention of the ceramic high temperature superconductor MHD drive, which is cooled with liquid hydrogen. The hydrogen is obtained electro-chemically directly from seawater, and is liquified magneto-calorically. The high temperature superconductor elements of the engine, liquifier, generator, storage coil, permanent magnet hollow cylinder store are coupled by a common liquid hydrogen cooling circuit. The internal combustion engine driving the generator is fuelled by the same liquid hydrogen by which the high temperature superconductor elements are cooled.

  4. Oscillating Permanent Magnets.

    Science.gov (United States)

    Michaelis, M. M.; Haines, C. M.

    1989-01-01

    Describes several ways to partially levitate permanent magnets. Computes field line geometries and oscillation frequencies. Provides several diagrams illustrating the mechanism of the oscillation. (YP)

  5. Quench in high temperature superconductor magnets

    CERN Document Server

    Schwartz, J

    2013-01-01

    High field superconducting magnets using high temperature superconductors are being developed for high energy physics, nuclear magnetic resonance and energy storage applications. Although the conductor technology has progressed to the point where such large magnets can be readily envisioned, quench protection remains a key challenge. It is well-established that quench propagation in HTS magnets is very slow and this brings new challenges that must be addressed. In this paper, these challenges are discussed and potential solutions, driven by new technologies such as optical fiber based sensors and thermally conducting electrical insulators, are reviewed.

  6. Comparing superconducting and permanent magnets for magnetic refrigeration

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Nielsen, Kaspar Kirstein; Bahl, C. R. H.

    2016-01-01

    We compare the cost of a high temperature superconducting (SC) tape-based solenoidwith a permanent magnet (PM) Halbach cylinder for magnetic refrigeration.Assuming a five liter active magnetic regenerator volume, the price of each type ofmagnet is determined as a function of aspect ratio of the r......We compare the cost of a high temperature superconducting (SC) tape-based solenoidwith a permanent magnet (PM) Halbach cylinder for magnetic refrigeration.Assuming a five liter active magnetic regenerator volume, the price of each type ofmagnet is determined as a function of aspect ratio...

  7. High temperature superconductors for magnetic suspension applications

    Science.gov (United States)

    Mcmichael, C. K.; Cooley, R. S.; Chen, Q. Y.; Ma, K. B.; Lamb, M. A.; Meng, R. L.; Chu, C. W.; Chu, W. K.

    1994-01-01

    High temperature superconductors (HTS) hold the promise for applications in magnetic levitation bearings, vibration damping, and torque coupling. Traditional magnetic suspension systems require active feedback and vibration controls in which power consumption and low frequency vibration are among the major engineering concerns. HTS materials have been demonstrated to be an enabling approach towards such problems due to their flux trapping properties. In our laboratory at TCSUH, we have been conducting a series of experiments to explore various mechanical applications using HTS. We have constructed a 30 lb. model flywheel levitated by a hybrid superconducting magnetic bearing (HSMB). We are also developing a levitated and vibration-dampled platform for high precision instrumentation. These applications would be ideal for space usages where ambient temperature is adequate for HTS to operate properly under greatly reduced cryogenic requirements. We will give a general overview of these potential applications and discuss the operating principles of the HTS devices we have developed.

  8. Fail Safe, High Temperature Magnetic Bearings

    Science.gov (United States)

    Minihan, Thomas; Palazzolo, Alan; Kim, Yeonkyu; Lei, Shu-Liang; Kenny, Andrew; Na, Uhn Joo; Tucker, Randy; Preuss, Jason; Hunt, Andrew; Carter, Bart; hide

    2002-01-01

    This paper contributes to the magnetic bearing literature in two distinct areas: high temperature and redundant actuation. Design considerations and test results are given for the first published combined 538 C (1000 F) high speed rotating test performance of a magnetic bearing. Secondly, a significant extension of the flux isolation based, redundant actuator control algorithm is proposed to eliminate the prior deficiency of changing position stiffness after failure. The benefit of the novel extension was not experimentally demonstrated due to a high active stiffness requirement. In addition, test results are given for actuator failure tests at 399 C (750 F), 12,500 rpm. Finally, simulation results are presented confirming the experimental data and validating the redundant control algorithm.

  9. Permanent magnet design methodology

    Science.gov (United States)

    Leupold, Herbert A.

    1991-01-01

    Design techniques developed for the exploitation of high energy magnetically rigid materials such as Sm-Co and Nd-Fe-B have resulted in a revolution in kind rather than in degree in the design of a variety of electron guidance structures for ballistic and aerospace applications. Salient examples are listed. Several prototype models were developed. These structures are discussed in some detail: permanent magnet solenoids, transverse field sources, periodic structures, and very high field structures.

  10. High-temperature superconducting undulator magnets

    Science.gov (United States)

    Kesgin, Ibrahim; Kasa, Matthew; Ivanyushenkov, Yury; Welp, Ulrich

    2017-04-01

    This paper presents test results on a prototype superconducting undulator magnet fabricated using 15% Zr-doped rare-earth barium copper oxide high temperature superconducting (HTS) tapes. On an 11-pole magnet we demonstrate an engineering current density, J e, of more than 2.1 kA mm‑2 at 4.2 K, a value that is 40% higher than reached in comparable devices wound with NbTi-wire, which is used in all currently operating superconducting undulators. A novel winding scheme enabling the continuous winding of tape-shaped conductors into the intricate undulator magnets as well as a partial interlayer insulation procedure were essential in reaching this advance in performance. Currently, there are rapid advances in the performance of HTS; therefore, achieving even higher current densities in an undulator structure or/and operating it at temperatures higher than 4.2 K will be possible, which would substantially simplify the cryogenic design and reduce overall costs.

  11. Permanent-Magnet Meissner Bearing

    Science.gov (United States)

    Robertson, Glen A.

    1994-01-01

    Permanent-magnet meissner bearing features inherently stable, self-centering conical configuration. Bearing made stiffer or less stiff by selection of magnets, springs, and spring adjustments. Cylindrical permanent magnets with axial magnetization stacked coaxially on rotor with alternating polarity. Typically, rare-earth magnets used. Magnets machined and fitted together to form conical outer surface.

  12. High temperature superconducting axial field magnetic coupler: realization and test

    Science.gov (United States)

    Belguerras, L.; Mezani, S.; Lubin, T.; Lévêque, J.; Rezzoug, A.

    2015-09-01

    Contactless torque transmission through a large airgap is required in some industrial applications in which hermetic isolation is necessary. This torque transmission usually uses magnetic couplers, whose dimension strongly depends on the airgap flux density. The use of high temperature superconducting (HTS) coils to create a strong magnetic field may constitute a solution to reduce the size of the coupler. It is also possible to use this coupler to replace a torque tube in transmitting the torque produced by a HTS motor to its load. This paper presents the detailed construction and tests of an axial field HTS magnetic coupler. Pancake coils have been manufactured from BSCCO tape and used in one rotor of the coupler. The second rotor is mainly composed of NdFeB permanent magnets. Several tests have been carried out showing that the constructed coupler is working properly. A 3D finite element (FE) model of the studied coupler has been developed. Airgap magnetic field and torque measurements have been carried out and compared to the FE results. It has been shown that the measured and the computed quantities are in satisfactory agreement.

  13. Magnetic guns with cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, David; Beleggia, Marco; Heller, Luděk

    2012-01-01

    The motion of a cylindrical permanent magnet (projectile) inside a tubular permanent magnet, with both magnets magnetized axially, illustrates nicely the physical principles behind the operation of magnetic guns. The force acting upon the projectile is expressed semi-analytically as derivative...

  14. Calculating levitation forces in the magnet-high-temperature superconductor systems

    NARCIS (Netherlands)

    Ermolaev, YS; Rudnev, IA

    2005-01-01

    A new method of calculation of the magnetic levitation force in the permanent magnet-high-temperature superconductor systems is proposed based on the Maxwell equations and the Bean model. The dependences of the levitation force on the gap width calculated for various regimes of superconductor coolin

  15. Calculating levitation forces in the magnet-high-temperature superconductor systems

    NARCIS (Netherlands)

    Ermolaev, YS; Rudnev, IA

    2005-01-01

    A new method of calculation of the magnetic levitation force in the permanent magnet-high-temperature superconductor systems is proposed based on the Maxwell equations and the Bean model. The dependences of the levitation force on the gap width calculated for various regimes of superconductor coolin

  16. Electromagnetic acceleration of permanent magnets

    CERN Document Server

    Dolya, S N

    2015-01-01

    We consider the acceleration of the permanent magnets, consisting of neodymium iron boron by means of the running magnetic field gradient. It is shown that the specific magnetic moment per nucleon in neodymium iron boron is determined by the remained magnetization of the substance. The maximum accessable gradient of the magnetic field accelerating the permanent magnets is determined by the coercive force thirty kilogauss. For the neodymium iron boron magnets this gradient is equal to twenty kilogauss divided by one centimeter. The finite velocity of the magnets six kilometers per second, the length of acceleration is six hundred thirty-seven meters.

  17. Lodestone: Nature's own permanent magnet

    Science.gov (United States)

    Wasilewski, P.

    1976-01-01

    Magnetic hysteresis and microstructural details are presented which explain why the class of magnetic iron ores defined as proto-lodestones, can behave as permanent magnets, i.e. lodestones. Certain of these proto-lodestones which are not permanent magnets can be made into permanent magnets by charging in a field greater than 1000 oersted. This fact, other experimental observations, and field evidence from antiquity and the middle ages, which seems to indicate that lodestones are found as localized patches within massive ore bodies, suggests that lightning might be responsible for the charging of lodestones. The large remanent magnetization, high values of coercive force, and good time stability for the remanent magnetization are all characteristics of proto-lodestone iron ores which behave magnetically as fine scale ( 10 micrometer) intergrowths when subjected to magnetic hysteresis analysis. The magnetic results are easily understood by analysis of the complex proto lodestone microstructural patterns observable at the micrometer scale and less.

  18. Probing High Temperature Superconductors with Magnetometry in Ultrahigh Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lu [Univ. of Michigan, Ann Arbor, MI (United States)

    2017-07-26

    The objective of this research is to investigate the high-field magnetic properties of high temperature superconductors, materials that conduct electricity without loss. A technique known as high-resolution torque magnetometry that was developed to directly measure the magnetization of high temperature superconductors. This technique was implemented using the 65 Tesla pulsed magnetic field facility that is part of the National High Magnetic Field Laboratory at Los Alamos National Laboratory. This research addressed unanswered questions about the interplay between magnetism and superconductivity, determine the electronic structure of high temperature superconductors, and shed light on the mechanism of high temperature superconductivity and on potential applications of these materials in areas such as energy generation and power transmission. Further applications of the technology resolve the novel physical phenomena such as correlated topological insulators, and spin liquid state in quantum magnets.

  19. High temperature superconductor cable concepts for fusion magnets

    CERN Document Server

    AUTHOR|(CDS)2078397

    2013-01-01

    Three concepts of high temperature superconductor cables carrying kA currents (RACC, CORC and TSTC) are investigated, optimized and evaluated in the scope of their applicability as conductor in fusion magnets. The magnetic field and temperature dependence of the cables is measured; the thermal expansion and conductivity of structure, insulation and filling materials are investigated. High temperature superconductor winding packs for fusion magnets are calculated and compared with corresponding low temperature superconductor cases.

  20. Inorganic Nanostructured High-Temperature Magnet Wires Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will develop a high-temperature tolerant electrically-insulating coating for magnet wires. The Phase I program will result in a flexible, inorganic...

  1. Radiation Shielding Utilizing A High Temperature Superconducting Magnet Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project aims to leverage near-term high-temperature superconducting technologies to assess applicability of magnetic shielding for protecting against exposure...

  2. Magnetic Fields: Visible and Permanent.

    Science.gov (United States)

    Winkeljohn, Dorothy R.; Earl, Robert D.

    1983-01-01

    Children will be able to see the concept of a magnetic field translated into a visible reality using the simple method outlined. Standard shelf paper, magnets, iron filings, and paint in a spray can are used to prepare a permanent and well-detailed picture of the magnetic field. (Author/JN)

  3. High temperature superconductivity induced by incipient magnetism

    Science.gov (United States)

    Weger, M.; Pereg, Y.

    1990-10-01

    We consider the BCS gap equation, with an attractive interaction λ with an upper cutoff ω 0 and lower cutoff ω 1, and a repulsive interaction μ with cutoffΓ. We consider parameters such that a superconducting solution does not exist. We add a repulsive interaction ν eith cutoff ω1 ( ω1 < ω0), and show that this repulsive interaction (that we attribute to incipient magnetism) induces a superconducting state possessing a high transition temperature. In this state, the gap function Δ(ɛ) oscillates as function of ɛ, with a period of order ω 0. We also find solutions antisymmetric in energy [ Δ( ɛ) = - Δ(- ɛ) ], which turn out to be almost degenerate with the normal, symmetric ones. We discuss the physical implications of this model. Our model thus combines a low frequency repulsion due to antiferromagnetic interactions, with excitonic attraction at intermediate frequencies, and ordinary Coulomb repulsion above that. All frequency ranges, and coupling strengths, are comparable with the bandwidth.

  4. Cryocooler applications for high-temperature superconductor magnetic bearings.

    Energy Technology Data Exchange (ETDEWEB)

    Niemann, R. C.

    1998-05-22

    The efficiency and stability of rotational magnetic suspension systems are enhanced by the use of high-temperature superconductor (HTS) magnetic bearings. Fundamental aspects of the HTS magnetic bearings and rotational magnetic suspension are presented. HTS cooling can be by liquid cryogen bath immersion or by direct conduction, and thus there are various applications and integration issues for cryocoolers. Among the numerous cryocooler aspects to be considered are installation; operating temperature; losses; and vacuum pumping.

  5. Permanent magnet system of alpha magnetic spectrometer

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Alpha magnetic spectrometer (AMS) is the first large magnetic spectrometer in space. Its precursor flight was completed successfully in June 1998. The key part of AMS is the permanent magnet system, which was built by the Institute of Electric Engineering, the Institute of High Energy Physics and the Chinese Academy of Launch Vehicle Technology. This system includes a permanent magnet made of high grade NdFeB and a support structure. The unique design of the permanent magnet based on the magic ring fulfills the severe requirements on the magnetic field leakage and the dipole moment for space experiments. The permanent magnet weighs about 2 tons, and provides a geometric acceptance of 0.6 m2 ·sr and an analyzing power BL2 of 0.135 T·m2. It works up to 40℃ without demagnetization. The main structure is a thin double shell, which undergoes the strong magnetic force and torque of the permanent magnet, as well as the large load during launching and landing. The permanent magnet system fulfills the requirements from AMS, and satisfies the strict safety standards of NASA.

  6. Permanent magnet system of alpha magnetic spectrometer

    Institute of Scientific and Technical Information of China (English)

    陈和生

    2000-01-01

    Alpha magnetic spectrometer (AMS) is the first large magnetic spectrometer in space. Its precursor flight was completed successfully in June 1998. The key part of AMS is the permanent magnet system, which was built by the Institute of Electric Engineering, the Institute of High Energy Physics and the Chinese Academy of Launch Vehicle Technology. This system includes a permanent magnet made of high grade NdFeB and a support structure. The unique design of the permanent magnet based on the magic ring fulfills the severe requirements on the magnetic field leakage and the dipole moment for space experiments. The permanent magnet weighs about 2 tons, and provides a geometric acceptance of 0.6 m2·sr and an analyzing power BL2 of 0.135 T·m2. It works up to 40℃ without demagnetization. The main structure is a thin double shell, which undergoes the strong magnetic force and torque of the permanent magnet, as well as the large load during launching and landing. The permanent magnet system fulfills the requirem

  7. Manganese-based Permanent Magnets

    Directory of Open Access Journals (Sweden)

    Ian Baker

    2015-08-01

    Full Text Available There is a significant gap between the energy product, BH, where B is the magnetic flux density and H is the magnetic field strength, of both the traditional ferrite and AlNiCo permanent magnets of less than 10 MGOe and that of the rare earth magnets of greater than 30 MGOe. This is a gap that Mn-based magnets could potentially, inexpensively, fill. This Special Issue presents work on the development of both types of manganese permanent magnets. Some of the challenges involved in the development of these magnets include improving the compounds’ energy product, increasing the thermal stability of these metastable compounds, and producing them in quantity as a bulk material.[...

  8. Overview on permanent magnetic actuator

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Permanent magnetic actuator (PMA), as a new electronic actuator of vacuum circuit breakers, certainly will be used to replace the traditional mechanical actuator. It has such advantages as simple structure, high reliability, free maintenance, and so on. This paper summarizes the development, structure, magnetic analysis, character analysis, and control strategy of PMA, and also predicts the future trend of PMA development

  9. Topology optimized permanent magnet systems

    CERN Document Server

    Bjørk, R; Insinga, A R

    2016-01-01

    Topology optimization of permanent magnet systems consisting of permanent magnets, high permeability iron and air is presented. An implementation of topology optimization for magnetostatics is discussed and three examples are considered. First, the Halbach cylinder is topology optimized with iron and an increase of 15% in magnetic efficiency is shown, albeit with an increase of 3.8 pp. in field inhomogeneity - a value compared to the inhomogeneity in a 16 segmented Halbach cylinder. Following this a topology optimized structure to concentrate a homogeneous field is shown to increase the magnitude of the field by 111% for the chosen dimensions. Finally, a permanent magnet with alternating high and low field regions is considered. Here a $\\Lambda_\\mathrm{cool}$ figure of merit of 0.472 is reached, which is an increase of 100% compared to a previous optimized design.

  10. Comparing superconducting and permanent magnets for magnetic refrigeration

    Directory of Open Access Journals (Sweden)

    R. Bjørk

    2016-05-01

    Full Text Available We compare the cost of a high temperature superconducting (SC tape-based solenoid with a permanent magnet (PM Halbach cylinder for magnetic refrigeration. Assuming a five liter active magnetic regenerator volume, the price of each type of magnet is determined as a function of aspect ratio of the regenerator and desired internal magnetic field. It is shown that to produce a 1 T internal field in the regenerator a permanent magnet of hundreds of kilograms is needed or an area of superconducting tape of tens of square meters. The cost of cooling the SC solenoid is shown to be a small fraction of the cost of the SC tape. Assuming a cost of the SC tape of 6000 $/m2 and a price of the permanent magnet of 100 $/kg, the superconducting solenoid is shown to be a factor of 0.3-3 times more expensive than the permanent magnet, for a desired field from 0.5-1.75 T and the geometrical aspect ratio of the regenerator. This factor decreases for increasing field strength, indicating that the superconducting solenoid could be suitable for high field, large cooling power applications.

  11. A new ring-shape high-temperature superconducting trapped-field magnet

    Science.gov (United States)

    Sheng, Jie; Zhang, Min; Wang, Yawei; Li, Xiaojian; Patel, Jay; Yuan, Weijia

    2017-09-01

    This paper presents a new trapped-field magnet made of second-generation high-temperature superconducting (2G HTS) rings. This so-called ring-shape 2G HTS magnet has the potential to provide much stronger magnetic fields relative to existing permanent magnets. Compared to existing 2G HTS trapped- field magnets, e.g. 2G HTS bulks and stacks, this new ring-shape 2G HTS magnet is more flexible in size and can be made into magnets with large dimensions for industrial applications. Effective magnetization is the key to being able to use trapped-field magnets. Therefore, this paper focuses on the magnetization mechanism of this new magnet using both experimental and numerical methods. Unique features have been identified and quantified for this new type of HTS magnet in the field cooling and zero field cooling process. The magnetization mechanism can be understood by the interaction between shielding currents and the penetration of external magnetic fields. An accumulation in the trapped field was observed by using multiple pulse field cooling. Three types of demagnetization were studied to measure the trapped-field decay for practical applications. Our results show that this new ring-shape HTS magnet is very promising in the trapping of a high magnetic field. As a super-permanent magnet, it will have a significant impact on large-scale industrial applications, e.g. the development of HTS machines with a very high power density and HTS magnetic resonance imaging devices.

  12. The cycloid Permanent Magnetic Gear

    DEFF Research Database (Denmark)

    Rasmussen, Peter Omand; Andersen, Torben Ole; Jørgensen, Frank T.

    2008-01-01

    This paper presents a new permanent-magnet gear based on the cycloid gearing principle. which normally is characterized by an extreme torque density and a very high gearing ratio. An initial design of the proposed magnetic gear was designed, analyzed, and optimized with an analytical model...... regarding torque density. The results were promising as compared to other high-performance magnetic-gear designs. A test model was constructed to verify the analytical model....

  13. Rare earth elements and permanent magnets (invited)

    Science.gov (United States)

    Dent, Peter C.

    2012-04-01

    Rare earth (RE) magnets have become virtually indispensible in a wide variety of industries such as aerospace, automotive, electronics, medical, and military. RE elements are essential ingredients in these high performance magnets based on intermetallic compounds RECo5, RE2TM17 (TM: transition metal), and RE2TM14B. Rare earth magnets are known for their superior magnetic properties—high induction, and coercive force. These properties arise due to the extremely high magnetocrystalline anisotropy made possible by unique 3d-4f interactions between transition metals and rare earths. For more than 40 years, these magnets remain the number one choice in applications that require high magnetic fields in extreme operating conditions—high demagnetization forces and high temperature. EEC produces and specializes in RECo5 and RE2TM17 type sintered magnets. Samarium and gadolinium are key RE ingredients in the powder metallurgical magnet production processes which include melting, crushing, jet milling, pressing, sintering, and heat treating. The magnetic properties and applications of these magnets will be discussed. We will also briefly discuss the past, current, and future of the permanent magnet business. Currently, over 95% of all pure rare earth oxides are sourced from China, which currently controls the market. We will provide insights regarding current and potential new magnet technologies and designer choices, which may mitigate rare earth supply chain issues now and into the future.

  14. Permanent magnets including undulators and wigglers

    OpenAIRE

    Bahrdt, J.

    2011-01-01

    After a few historic remarks on magnetic materials we introduce the basic definitions related to permanent magnets. The magnetic properties of the most common materials are reviewed and the production processes are described. Measurement techniques for the characterization of macroscopic and microscopic properties of permanent magnets are presented. Field simulation techniques for permanent magnet devices are discussed. Today, permanent magnets are used in many fields. This article concentrat...

  15. PERMANENT-MAGNET INDUCTION GENERATORS: AN OVERVIEW

    Directory of Open Access Journals (Sweden)

    K. S. S. RAMAKRISHNAN

    2011-06-01

    Full Text Available The advantage of using a permanent-magnet induction generator (PMIG instead of a conventional induction generator is its ability to suppress inrush current during system linking when synchronous input is performed. Induction machines excited with permanent-magnet (PM are called permanent-magnet induction generators. This paper presents an exhaustive survey of the literature discussing the classification of permanent-magnet machines, process of permanent-magnet excitation and voltage build-up, modelling, steady-state and performance analysis of the permanent-magnet induction generators.

  16. 21 CFR 886.4445 - Permanent magnet.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Permanent magnet. 886.4445 Section 886.4445 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4445 Permanent magnet. (a) Identification. A permanent magnet is a nonelectric device that generates a magnetic field intended to find and remove...

  17. Trans-permanent magnetic actuation

    Science.gov (United States)

    Farmer, Daniel Jay

    The demands for an actuator to deploy, position and shape large spaced-based structures form a unique set of design criteria. In many applications it is desirable to hold displacements or forces between two points to within specified requirements (the regulation problem) and to periodically to change position (the tracking problem). Furthermore, the interest generally lies in satisfying the dynamic performance requirements while expending minimal power, while meeting tight tolerances and while experiencing little wear and fatigue. The actuator must also be able to withstand a variety of operational conditions such as impacts and thermal changes over an extended period of time. Current trends in large-scale structures have addressed the demands by using conventional actuators and motors, along with elaborate linkages or mechanisms to shape, position, protect and deploy. The developed designs use unique characteristics of permanent magnets to create simple direct-acting actuators and motors very suitable for space based structures. The developed trans-permanent magnetic (T-PM) actuators and motors are systems consisting of one or more permanent magnets, some of whose magnetic strengths can be switched on-board by surrounding pulse-coils. The T-PM actuator and motors expend no power during regulation. The T-PM can periodically change or remove the strength of its own magnets thereby enabling both fine-tune adjustments (microsteps) and large-scale adjustments (rotation). The fine (microstep) adjustments are particularly helpful in thermally varying space environments. The large-scale adjustments (rotation) are particularly helpful in deployment where the structure or antenna must experience large-angle rotations and/or large displacements. T-PM concepts are illustrated in direct acting actuators and built into stepper motor and permanent magnet motor applications. Several examples of design, analysis and testing are developed to verify the technology and supporting

  18. Low field magnetic measurements on high temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, G.; Murphy, S.D.; Li, Z.Y.; Stewart, A.M.; Bhagat, S.M. (Maryland Univ., College Park, MD (USA). Dept. of Physics and Astronomy)

    1989-09-01

    The authors report dc magnetization and ac susceptibility measurements on both micron size powders and sintered samples of several high temperature superconductors. The powder data confirm previous findings that the materials can be treated as conventional superconductors with s-wave pairing. The ac results on sintered slabs ar interpreted using Bean's model and yield the temperature dependence of the shielding current.

  19. Study of flow fractionation characteristics of magnetic chromatography utilizing high-temperature superconducting bulk magnet

    Directory of Open Access Journals (Sweden)

    Satoshi Fukui, Yoshihiro Shoji, Jun Ogawa, Tetsuo Oka, Mitsugi Yamaguchi, Takao Sato, Manabu Ooizumi, Hiroshi Imaizumi and Takeshi Ohara

    2009-01-01

    Full Text Available We present numerical simulation of separating magnetic particles with different magnetic susceptibilities by magnetic chromatography using a high-temperature superconducting bulk magnet. The transient transport is numerically simulated for two kinds of particles having different magnetic susceptibilities. The time evolutions were calculated for the particle concentration in the narrow channel of the spiral arrangement placed in the magnetic field. The field is produced by the highly magnetized high-temperature superconducting bulk magnet. The numerical results show the flow velocity difference of the particle transport corresponding to the difference in the magnetic susceptibility, as well as the possible separation of paramagnetic particles of 20 nm diameter.

  20. High-Temperature, High-Load-Capacity Radial Magnetic Bearing

    Science.gov (United States)

    Provenza, Andrew; Montague, Gerald; Kascak, Albert; Palazzolo, Alan; Jansen, Ralph; Jansen, Mark; Ebihara, Ben

    2005-01-01

    A radial heteropolar magnetic bearing capable of operating at a temperature as high as 1,000 F (=540 C) has been developed. This is a prototype of bearings for use in gas turbine engines operating at temperatures and speeds much higher than can be withstood by lubricated rolling-element bearings. It is possible to increase the maximum allowable operating temperatures and speeds of rolling-element bearings by use of cooling-air systems, sophisticated lubrication systems, and rotor-vibration- damping systems that are subsystems of the lubrication systems, but such systems and subsystems are troublesome. In contrast, a properly designed radial magnetic bearing can suspend a rotor without contact, and, hence, without need for lubrication or for cooling. Moreover, a magnetic bearing eliminates the need for a separate damping system, inasmuch as a damping function is typically an integral part of the design of the control system of a magnetic bearing. The present high-temperature radial heteropolar magnetic bearing has a unique combination of four features that contribute to its suitability for the intended application: 1. The wires in its electromagnet coils are covered with an insulating material that does not undergo dielectric breakdown at high temperature and is pliable enough to enable the winding of the wires to small radii. 2. The processes used in winding and potting of the coils yields a packing factor close to 0.7 . a relatively high value that helps in maximizing the magnetic fields generated by the coils for a given supplied current. These processes also make the coils structurally robust. 3. The electromagnets are of a modular C-core design that enables replacement of components and semiautomated winding of coils. 4. The stator is mounted in such a manner as to provide stable support under radial and axial thermal expansion and under a load as large as 1,000 lb (.4.4 kN).

  1. Permanent magnet with MgB2 bulk superconductor

    Science.gov (United States)

    Yamamoto, Akiyasu; Ishihara, Atsushi; Tomita, Masaru; Kishio, Kohji

    2014-07-01

    Superconductors with persistent zero-resistance currents serve as permanent magnets for high-field applications requiring a strong and stable magnetic field, such as magnetic resonance imaging. The recent global helium shortage has quickened research into high-temperature superconductors (HTSs)—materials that can be used without conventional liquid-helium cooling to 4.2 K. Herein, we demonstrate that 40-K-class metallic HTS magnesium diboride (MgB2) makes an excellent permanent bulk magnet, maintaining 3 T at 20 K for 1 week with an extremely high stability (cryocoolers, making MgB2 bulks promising for the next generation of Tesla-class permanent-magnet applications.

  2. High-Temperature Magnetic Bearings for Gas Turbine Engines

    Science.gov (United States)

    1996-01-01

    Magnetic bearings are the subject of a new NASA Lewis Research Center and U.S. Army thrust with significant industry participation, and coordination with other Government agencies. The NASA/Army emphasis is on high-temperature applications for future gas turbine engines. Magnetic bearings could increase the reliability and reduce the weight of these engines by eliminating the lubrication system. They could also increase the DN (diameter of the bearing times rpm) limit on engine speed and allow active vibration cancellation systems to be used--resulting in a more efficient, "more electric" engine. Finally, the Integrated High-Performance Turbine Engine Technology (IHPTET) Program, a joint Department of Defense/industry program, identified a need for a hightemperature (as high as 1200 F) magnetic bearing that could be demonstrated in a phase III engine. This magnetic bearing is similar to an electric motor. It has a laminated rotor and stator made of cobalt steel. Wound around the stator are a series of electrical wire coils that form a series of electric magnets around the circumference. The magnets exert a force on the rotor. A probe senses the position of the rotor, and a feedback controller keeps it in the center of the cavity. The engine rotor, bearings, and case form a flexible structure that contains a large number of modes. The bearing feedback controller, which could cause some of these modes to become unstable, could be adapted to varying flight conditions to minimize seal clearances and monitor the health of the system. Cobalt steel has a curie point greater than 1700 F, and copper wire has a melting point beyond that. Therefore, practical limitations associated with the maximum magnetic field strength in the cobalt steel and the stress in the rotating components limit the temperature to about 1200 F. The objective of this effort is to determine the limits in temperature and speed of a magnetic bearing operating in an engine. Our approach is to use our in

  3. Novel Switched Flux Permanent Magnet Machine Topologies

    Institute of Scientific and Technical Information of China (English)

    诸自强

    2012-01-01

    This paper overviews various switched flux permanent magnet machines and their design and performance features,with particular emphasis on machine topologies with reduced magnet usage or without using magnet,as well as with variable flux capability.

  4. New permanent magnets; manganese compounds.

    Science.gov (United States)

    Coey, J M D

    2014-02-12

    The exponential growth of maximum energy product that prevailed in the 20th century has stalled, leaving a market dominated by two permanent magnet materials, Nd2Fe14B and Ba(Sr)Fe12O19, for which the maximum theoretical energy products differ by an order of magnitude (515 kJ m(-3) and 45 kJ m(-3), respectively). Rather than seeking to improve on optimized Nd-Fe-B, it is suggested that some research efforts should be devoted to developing appropriately priced alternatives with energy products in the range 100-300 kJ m(-3). The prospects for Mn-based hard magnetic materials are discussed, based on known Mn-based compounds with the tetragonal L10 or D022 structure or the hexagonal B81 structure.

  5. Finite element modeling of permanent magnet devices

    Science.gov (United States)

    Brauer, J. R.; Larkin, L. A.; Overbye, V. D.

    1984-03-01

    New techniques are presented for finite element modeling of permanent magnets in magnetic devices such as motors and generators. These techniques extend a previous sheet-current permanent magnet model that applies only for straight line B-H loops and rectangular-shaped magnets. Here Maxwell's equations are used to derive the model of a permanent magnet having a general curved B-H loop and any geometric shape. The model enables a nonlinear magnetic finite element program to use Newton-Raphson iteration to solve for saturable magnetic fields in a wide variety of devices containing permanent magnets and steels. The techniques are applied to a brushless dc motor with irregular-shaped permanent magnets. The calculated motor torque agrees well with measured torque.

  6. Effect of permanent-magnet irregularities in levitation force measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Hull, J. R.

    1999-10-14

    In the measurement of the levitation force between a vertically magnetized permanent magnet (PM) and a bulk high-temperature superconductor (HTS), PM domains with horizontal components of magnetization are shown to produce a nonnegligible contribution to the levitation force in most systems. Such domains are typically found in all PMs, even in those that exhibit zero net horizontal magnetic moment. Extension of this analysis leads to an HTS analog of Earnshaw's theorem, in which at the field-cooling position the vertical stiffness is equal to the sum of the horizontal stiffnesses, independent of angular distribution of magnetic moments within the PM.

  7. Effect of permanent-magnet irregularities in levitation force measurements

    Science.gov (United States)

    Hull, John R.

    2000-06-01

    In the measurement of the levitation force between a vertically magnetized permanent magnet (PM) and a bulk high-temperature superconductor (HTS), PM domains with horizontal components of magnetization are shown to produce a non-negligible contribution to the levitation force in most systems. Such domains are typically found in all PMs, even in those that exhibit zero net horizontal magnetic moment. Extension of this analysis leads to an HTS analogue of Earnshaw's theorem, in which the vertical stiffness is equal to the sum of the horizontal stiffness at the field-cooling position, independent of the angular distribution of magnetic moments within the PM.

  8. Effect of permanent-magnet irregularities in levitation force measurements

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. [Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2000-06-01

    In the measurement of the levitation force between a vertically magnetized permanent magnet (PM) and a bulk high-temperature superconductor (HTS), PM domains with horizontal components of magnetization are shown to produce a non-negligible contribution to the levitation force in most systems. Such domains are typically found in all PMs, even in those that exhibit zero net horizontal magnetic moment. Extension of this analysis leads to an HTS analogue of Earnshaw's theorem, in which the vertical stiffness is equal to the sum of the horizontal stiffness at the field-cooling position, independent of the angular distribution of magnetic moments within the PM. (author)

  9. The AC magnetic susceptibility of high temperature superconductors

    CERN Document Server

    Salim, M

    2001-01-01

    This research concerns the development of AC magnetic susceptometers and use of susceptometers in analysing high temperature superconductors. Two of the designs were a differential magnetic susceptometer (DMS) and a double coil screening susceptometer (DCSS) whose descriptions are given in detail including coil design, field measurements, susceptometer operation, experimental instrumentation, phase adjustment, susceptometer calibration and sensitivity for each design. Theoretical details are given regarding each design in order to calculate the complex external and internal susceptibility. Investigation concerning the demagnetisation factor of different geometries, and the significant features and limitation for each design are also provided. The susceptometers were applied to a wide range of YBCO samples, which includes bulk samples with different geometry (i.e. Slabs, disk, powder and thick film) and thin films with different oxygen contents. Several silver sheathed Bi-2223 tapes were also involved. This al...

  10. Development of high temperature superconductors for magnetic field applications

    Energy Technology Data Exchange (ETDEWEB)

    Larbalestier, D.C.

    1991-12-31

    The key requirement for magnetic field applications of high temperature superconductor (HTS) materials is to have conductors with high transport critical current density available for magnet builders. After 3 or 4 years of being without any such object, conductor makers have had recent success in producing simple conductor prototypes. These have permitted the construction of simple HTS magnets having self fields exceeding 1 tesla at 4K. Thus the scientific feasibility of making powerful HTS magnets has been demonstrated. Attention to the technological aspects of making HTS conductors for magnets with strong flux pinning and reduced superconducting granularity is now sensible and attractive. However, extrinsic defects such as filament sausaging, cracking, misaligned grains and other perturbation to long range current flow must be controlled at a low level if the benefit of intrinsic improvements to the critical current density is to be maintained in the conductor form. Due to the great complexity of the HTS materials, there is sometimes confusion as to whether a given sample has an intrinsically or extrinsically limited critical current density. Systematic microstructure variation experiments and resistive transition analysis are shown to be particularly helpful in this phase of conductor development.

  11. Development of high temperature superconductors for magnetic field applications

    Energy Technology Data Exchange (ETDEWEB)

    Larbalestier, D.C.

    1991-01-01

    The key requirement for magnetic field applications of high temperature superconductor (HTS) materials is to have conductors with high transport critical current density available for magnet builders. After 3 or 4 years of being without any such object, conductor makers have had recent success in producing simple conductor prototypes. These have permitted the construction of simple HTS magnets having self fields exceeding 1 tesla at 4K. Thus the scientific feasibility of making powerful HTS magnets has been demonstrated. Attention to the technological aspects of making HTS conductors for magnets with strong flux pinning and reduced superconducting granularity is now sensible and attractive. However, extrinsic defects such as filament sausaging, cracking, misaligned grains and other perturbation to long range current flow must be controlled at a low level if the benefit of intrinsic improvements to the critical current density is to be maintained in the conductor form. Due to the great complexity of the HTS materials, there is sometimes confusion as to whether a given sample has an intrinsically or extrinsically limited critical current density. Systematic microstructure variation experiments and resistive transition analysis are shown to be particularly helpful in this phase of conductor development.

  12. Magnetizing of permanent magnets using HTS bulk magnets

    Science.gov (United States)

    Oka, Tetsuo; Muraya, Tomoki; Kawasaki, Nobutaka; Fukui, Satoshi; Ogawa, Jun; Sato, Takao; Terasawa, Toshihisa

    2012-01-01

    A demagnetized Nd-Fe-B permanent magnet was scanned just above the magnetic pole which contains the HTS bulk magnet generating a magnetic field of 3.27 T. The magnet sample was subsequently found to be fully magnetized in the open space of the static magnetic fields. We examined the magnetic field distributions when the magnetic poles were scanned twice to activate the magnet plate inversely with various overlap distances between the tracks of the bulk magnet. The magnetic field of the "rewritten" magnet reached the values of the magnetically saturated region of the material, showing steep gradients at the border of each magnetic pole. As a replacement for conventional pulse field magnetizing methods, this technique is proposed to expand the degree of freedom in the design of electromagnetic devices, and is proposed as a novel practical method for magnetizing rare-earth magnets, which have excellent magnetic performance and require intense fields of more than 3 T to be activated.

  13. Comparison of adjustable permanent magnetic field sources

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Bahl, Christian Robert Haffenden; Smith, Anders

    2010-01-01

    A permanent magnet assembly in which the flux density can be altered by a mechanical operation is often significantly smaller than comparable electromagnets and also requires no electrical power to operate. In this paper five permanent magnet designs in which the magnetic flux density can...

  14. Permanent magnet with MgB{sub 2} bulk superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Akiyasu, E-mail: yamamoto@appchem.t.u-tokyo.ac.jp [The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); JST-PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Ishihara, Atsushi; Tomita, Masaru [Railway Technical Research Institute, 2-8-38 Hikari, Kokubunji, Tokyo 185-8540 (Japan); Kishio, Kohji [The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan)

    2014-07-21

    Superconductors with persistent zero-resistance currents serve as permanent magnets for high-field applications requiring a strong and stable magnetic field, such as magnetic resonance imaging. The recent global helium shortage has quickened research into high-temperature superconductors (HTSs)—materials that can be used without conventional liquid-helium cooling to 4.2 K. Herein, we demonstrate that 40-K-class metallic HTS magnesium diboride (MgB{sub 2}) makes an excellent permanent bulk magnet, maintaining 3 T at 20 K for 1 week with an extremely high stability (<0.1 ppm/h). The magnetic field trapped in this magnet is uniformly distributed, as for single-crystalline neodymium-iron-boron. Magnetic hysteresis loop of the MgB{sub 2} permanent bulk magnet was determined. Because MgB{sub 2} is a simple-binary-line compound that does not contain rare-earth metals, polycrystalline bulk material can be industrially fabricated at low cost and with high yield to serve as strong magnets that are compatible with conventional compact cryocoolers, making MgB{sub 2} bulks promising for the next generation of Tesla-class permanent-magnet applications.

  15. Micromachined permanent magnets and their MEMS applications

    Science.gov (United States)

    Cho, Hyoung Jin

    2002-01-01

    In this research, new micromachined permanent magnets have been proposed, developed and characterized for MEMS applications. In realizing micromachined permanent magnets, a new electroplating technique using external magnetic field and a bumper filling technique using a photolithographically defined mold with resin bonded magnetic particles have been developed. The newly developed micromachining techniques allow thick film-type permanent magnet components to be integrated to magnetic MEMS devices with dimensional control and alignment. Permanent magnet arrays with the dimensions ranging from 30 mum to 200 mum have been developed with an energy density up to 2.7 kJ/m3 in precisely defined forms in the micro scale. For the applications of the permanent magnets developed in this work, three novel magnetic MEMS devices such as a bi-directional magnetic actuator, a magnetically driven optical scanner, and a magnetic cell separator have been successfully realized. After design and modeling, each device has been fabricated and fully characterized. The bi-directional actuator with the electroplated permanent magnet array has achieved bi-directional motion clearly and shown good agreement with the analytical and simulated models. The optical scanner has shown linear bi-directional response under static actuation and stable bi-directional scanning performance under dynamic actuation. As a potential BioMEMS application of the developed permanent magnet, the prototype magnetic cell separator using the electroplated permanent magnet strip array has been proposed and demonstrated for magnetic bead patterning. In conclusion, new thick film-type, electroplated CoNiMnP and epoxy resin bonded Sr-ferrite permanent magnets have been developed and characterized, and then, three new magnetic MEMS devices using the permanent magnets such as a bi-directional magnetic actuator, an optical scanner and a magnetic cell separator have been realized in this research. The new micromachined

  16. Macroscopic Simulation of Isotropic Permanent Magnets

    CERN Document Server

    Bruckner, Florian; Vogler, Christoph; Heinrichs, Frank; Satz, Armin; Ausserlechner, Udo; Binder, Gernot; Koeck, Helmut; Suess, Dieter

    2015-01-01

    Accurate simulations of isotropic permanent magnets require to take the magnetization process into account and consider the anisotropic, nonlinear, and hysteretic material behaviour near the saturation configuration. An efficient method for the solution of the magnetostatic Maxwell equations including the description of isotropic permanent magnets is presented. The algorithm can easily be implemented on top of existing finite element methods and does not require a full characterization of the hysteresis of the magnetic material. Strayfield measurements of an isotropic permanent magnet and simulation results are in good agreement and highlight the importance of a proper description of the isotropic material.

  17. Macroscopic simulation of isotropic permanent magnets

    Science.gov (United States)

    Bruckner, Florian; Abert, Claas; Vogler, Christoph; Heinrichs, Frank; Satz, Armin; Ausserlechner, Udo; Binder, Gernot; Koeck, Helmut; Suess, Dieter

    2016-03-01

    Accurate simulations of isotropic permanent magnets require to take the magnetization process into account and consider the anisotropic, nonlinear, and hysteretic material behaviour near the saturation configuration. An efficient method for the solution of the magnetostatic Maxwell equations including the description of isotropic permanent magnets is presented. The algorithm can easily be implemented on top of existing finite element methods and does not require a full characterization of the hysteresis of the magnetic material. Strayfield measurements of an isotropic permanent magnet and simulation results are in good agreement and highlight the importance of a proper description of the isotropic material.

  18. resonant inverter supplied interior permanent magnet (ipm)

    African Journals Online (AJOL)

    user

    Permanent Magnet (IPM) or Surface Permanent. Magnet ... desired torque is produced to rotate the motor in the desired ... u axis, and the direct-axis of the rotor is at angle θ from the ..... Based Stator Flux Estimator” International. Journal of ...

  19. Macroscopic Simulation of Isotropic Permanent Magnets

    OpenAIRE

    Bruckner, Florian; Abert, Claas; Vogler, Christoph; Heinrichs, Frank; Satz, Armin; Ausserlechner, Udo; Binder, Gernot; Koeck, Helmut; Suess, Dieter

    2015-01-01

    Accurate simulations of isotropic permanent magnets require to take the magnetization process into account and consider the anisotropic, nonlinear, and hysteretic material behaviour near the saturation configuration. An efficient method for the solution of the magnetostatic Maxwell equations including the description of isotropic permanent magnets is presented. The algorithm can easily be implemented on top of existing finite element methods and does not require a full characterization of the...

  20. Design of microchannels for cryostabilization of high temperature superconducting magnets

    Science.gov (United States)

    Cha, Y. S.; Hull, J. R.; Niemann, R. C.

    Microchannel cooling using subcooled liquid nitrogen is proposed to cryogenically stabilize high-temperature superconducting magnets. Various design constraints and parameters are identified and summarized. A graphical method is proposed for the design of microchannel systems. This graphical method helps to reduce the amount of work towards achieving optimum design for a specific application because there are a large number of parameters involved in the design of a microchannel system. The proposed graphical method are illustrated by three examples. The results show that a design window may appear for a given application. Any point within this window is an acceptable design. Another advantage of the graphical method is that, by selecting a design point, the design margin against various design contrains can be easily identified. Any two of the design variables can be selected as the independent variables. The choice depends on specific application and, to a certain extent, on individual preference. The three examples revealed that, for high current density applications, the most scattering constraints are the coolant temperature rise and the fin tip temperatures provided that a moderate pressure drop can be tolerated.

  1. Permanent Magnetic Bearing for Spacecraft Applications

    Science.gov (United States)

    Morales, Winfredo; Fusaro, Robert; Kascak, Albert

    2008-01-01

    A permanent, totally passive magnetic bearing rig was designed, constructed, and tested. The suspension of the rotor was provided by two sets of radial permanent magnetic bearings operating in the repulsive mode. The axial support was provided by jewel bearings on both ends of the rotor. The rig was successfully operated to speeds of 5500 rpm using an air impeller. Radial and axial stiffnesses of the permanent magnetic bearings were experimentally measured and then compared to finite element results. The natural damping of the rotor was measured and a damping coefficient was calculated.

  2. A Cryogenic Magnetostrictive Actuator Using a Persistent High Temperature Superconducting Magnet. Part 1; Concept and Design

    Science.gov (United States)

    Horner, Garnett; Bromberg, Leslie; Teter, J. P.

    2000-01-01

    Cryogenic magnetostrictive materials, such as rare earth zinc crystals, offer high strains and high forces with minimally applied magnetic fields, making the material ideally suited for deformable optics applications. For cryogenic temperature applications the use of superconducting magnets offer the possibility of a persistent mode of operation, i.e., the magnetostrictive material will maintain a strain field without power. High temperature superconductors (HTS) are attractive options if the temperature of operation is higher than 10 degrees Kelvin (K) and below 77 K. However, HTS wires have constraints that limit the minimum radius of winding, and even if good wires can be produced, the technology for joining superconducting wires does not exist. In this paper, the design and capabilities of a rare earth zinc magnetostrictive actuator using bulk HTS is described. Bulk superconductors can be fabricated in the sizes required with excellent superconducting properties. Equivalent permanent magnets, made with this inexpensive material, are persistent, do not require a persistent switch as in HTS wires, and can be made very small. These devices are charged using a technique which is similar to the one used for charging permanent magnets, e.g., by driving them into saturation. A small normal conducting coil can be used for charging or discharging. Because of the magnetic field capability of the superconductor material, a very small amount of superconducting magnet material is needed to actuate the rare earth zinc. In this paper, several designs of actuators using YBCO and BSCCO 2212 superconducting materials are presented. Designs that include magnetic shielding to prevent interaction between adjacent actuators will also be described. Preliminary experimental results and comparison with theory for BSCCO 2212 with a magnetostrictive element will be discussed.

  3. ANALYTIC EXPRESSION OF MAGNETIC FIELD DISTRIBUTION OF RECTANGULAR PERMANENT MAGNETS

    Institute of Scientific and Technical Information of China (English)

    苟晓凡; 杨勇; 郑晓静

    2004-01-01

    From the molecular current viewpoint,an analytic expression exactly describing magnetic field distribution of rectangular permanent magnets magnetized sufficiently in one direction was derived from the Biot-Savart's law. This expression is useful not only for the case of one rectangular permanent magnet bulk, but also for that of several rectangular permanent magnet bulks. By using this expression,the relations between magnetic field distribution and the size of rectangular permanent magnets as well as the magnitude of magnetic field and the distance from the point in the space to the top (or bottom) surface of rectangular permanent magnets were discussed in detail. All the calculating results are consistent with experimental ones. For transverse magnetic field which is a main magnetic field of rectangular permanent magnets,in order to describe its distribution,two quantities,one is the uniformity in magnitude and the other is the uniformity in distribution of magnetic field,were defined. Furthermore, the relations between them and the geometric size of the magnet as well as the distance from the surface of permanent magnets were investigated by these formulas. The numerical results show that the geometric size and the distance have a visible influence on the uniformity in magnitude and the uniformity in distribution of the magnetic field.

  4. Improvement of the Levitation Characteristics in the Magnetic Bearing System Using HTSC-Permanent Magnet Hybrid Structure

    Science.gov (United States)

    Ohashi, Shunsuke

    Magnetic bearing using pining force of a permanent magnet and a high-temperature superconductor has been developed. Additional permanent magnet is introduced to increase the levitation force of the magnetic bearing. In this hybrid magnetic bearing system, levitation force is mainly given by the repulsive force of the permanent magnets, and stability for the lateral direction is given by pining force of the superconductor. The experimental device is developed. A ring type superconductor and a bulk one are examined. Levitation characteristics of the hybrid magnetic bearing are measured. A bulk superconductor shows better characteristics both levitation and lateral stability than ring one. Levitation force of the hybrid system becomes about twice as large as that of the no-hybrid one. Although repulsive force of the permanent magnet decreases lateral stability of the system, its influence becomes small by choosing adequate position of the permanent magnets and the superconductor.

  5. Design and construction of permanent magnetic gears

    OpenAIRE

    Jørgensen, Frank Thorleif

    2010-01-01

    This thesis deals with design and development of permanent magnetic gears. The goal of this thesis is to develop knowledge and calculation software for magnetic gears. They use strong NdFeB permanent magnets and a new magnetic gear technology, which will be a serious alternative to classical mechanical gears. The new magnetic gear will have a high torque density1 relationship –high efficiency and are maintenance free. In this project was manufactured two test gears which is tested and verifie...

  6. High performance magnetic bearing systems using high temperature superconductors

    Science.gov (United States)

    Abboud, Robert G.

    1998-01-01

    A magnetic bearing apparatus and a method for providing at least one stabilizing force in a magnetic bearing structure with a superconducting magnetic assembly and a magnetic assembly, by providing a superconducting magnetic member in the superconducting magnetic assembly with a plurality of domains and arranging said superconducting magnetic member such that at least one domain has a domain C-axis vector alignment angularly disposed relative to a reference axis of the magnetic member in the magnetic assembly.

  7. Permanent Magnet Boosted Modular Switched Reluctance Motor

    Directory of Open Access Journals (Sweden)

    SZABÓ Loránd

    2016-10-01

    Full Text Available This paper deals with the analyses of a novel motor structure obtained by boosting with permanent magnets a formerly studied modular switched reluctance motor. Upon dynamic simulation results the improvements of the proposed motor are emphasized.

  8. Design and construction of permanent magnetic gears

    DEFF Research Database (Denmark)

    Jørgensen, Frank Thorleif

    This thesis deals with design and development of permanent magnetic gears. The goal of this thesis is to develop knowledge and calculation software for magnetic gears. They use strong NdFeB permanent magnets and a new magnetic gear technology, which will be a serious alternative to classical...... calculation models for determination of gear output torque from different magnetic gear types are analysed. These analytical calculations models are used together with optimisation tools in order to improve the performance of investigated magnetic gear types. Experimental test gears are designed to validate...... is searched and only a single reference [74] is found and that is why the combination of a cycloidal gear and a magnetic gear are considered as an innovative supplement to magnetic gear technology. A magnetic cycloidal gear is designed with a gearing of 1:21 and a calculated active torque density of 142 [Nm...

  9. Pure-type superconducting permanent-magnet undulator.

    Science.gov (United States)

    Tanaka, Takashi; Tsuru, Rieko; Kitamura, Hideo

    2005-07-01

    A novel synchrotron radiation source is proposed that utilizes bulk-type high-temperature superconductors (HTSCs) as permanent magnets (PMs) by in situ magnetization. Arrays of HTSC blocks magnetized by external magnetic fields are placed below and above the electron path instead of conventional PMs, generating a periodic magnetic field with an offset. Two methods are presented to magnetize the HTSCs and eliminate the field offset, enabling the HTSC arrays to work as a synchrotron radiation source. An analytical formula to calculate the peak field achieved in a device based on this scheme is derived in a two-dimensional form for comparison with synchrotron radiation sources using conventional PMs. Experiments were performed to demonstrate the principle of the proposed scheme and the results have been found to be very promising.

  10. Quasi permanent superconducting magnet of very high field

    Science.gov (United States)

    Ren, Y.; Liu, J.; Weinstein, R.; Chen, I. G.; Parks, D.; Xu, J.; Obot, V.; Foster, C.

    1993-01-01

    We report on persistent field in a quasi-permanent magnet made of high temperature superconductor. The material has an average of 40 percent molar excess of Y, relative to Y1Ba2Cu3O7 and has been irradiated with high energy light ions at 200 MeV. The magnet, which traps 1.52 T at 77.3 K, traps nearly 4 T at 64.5 K. No evidence of giant flux jump or sample cracking was observed.

  11. Forces Between a Permanent Magnet and a Soft Magnetic Plate

    DEFF Research Database (Denmark)

    Beleggia, Marco; Vokoun, David; De Graef, Marc

    2012-01-01

    Forces between a hard/permanent magnet of arbitrary shape and an ideally soft magnetic plate in close proximity are derived analytically from the image method applied to magnetostatics. We found that the contact force, defined as the force required to detach the hard magnet from the plate......, coincides with that between two identical touching permanent magnets. Furthermore, if the hard and the soft magnets are displaced by some amount, their attraction equals that between two identical permanent magnets displaced by twice that amount. Experimental results are presented that validate...

  12. Improvement of the levitation stability of the HTSC-permanent magnet hybrid bearing by using the new arrangement of the permanent magnet

    Science.gov (United States)

    Sukedaia, M.; Emoto, K.; Sugiyama, R.; Ohashi, S.

    The hybrid magnetic bearing using permanent magnets and the high temperature superconductor (HTSC) has been developed. Repulsive force of the permanent magnet is introduced to increase the load weight of the magnetic bearing. Effect of the hybrid system has been shown. Although the previous configuration improves the load weight of the rotor, levitation and guidance stability has been decreased because of the repulsive force of the permanent magnet. Three-dimensional numerical analysis of the system has been undertaken to reduce lateral force which decreases lateral stability of the rotor. From the results, effective arrangement of the hybrid system is given. Increment of the load weight is confirmed. Influence of the hybrid system on the pinning force between the HTSC and the permanent magnet is shown to be smaller than previous one.

  13. Design of permanent magnetic solenoids for REGAE

    Energy Technology Data Exchange (ETDEWEB)

    Gehrke, Tim; Zeitler, Benno; Gruener, Florian [University of Hamburg and Center for Free-Electron Laser Science, Hamburg (Germany); Floettmann, Klaus [DESY, Hamburg (Germany); Manz, Stephanie [MPSD, University of Hamburg (Germany)

    2013-07-01

    The Relativistic Electron Gun for Atomic Exploration REGAE is a small linear accelerator at DESY in Hamburg, which produces short, low emittance electron bunches. Two future experiments at REGAE, an external injection experiment for Laser Wakefield Acceleration (LWA) and a time resolving Transmission Electron Microscopy (TEM) setup, require strong focusing magnets inside the target chamber. Permanent magnetic solenoids can provide the needed focusing strength due to their enormous surface current density, while having compact dimensions at the same time. Solenoids are fundamentally non-linear focusing elements whose non-linearity is worst for short, strong magnets as required for REGAE. The induced emittance growth is investigated and minimized for different setups with axially and radially magnetized annular magnets. Since permanent magnetic solenoids cannot be switched off but are not needed in every experiment at REGAE, a mechanical lifting-system and a magnetic shielding has to ensure, that the different experiments do not disturb each other.

  14. Permanent magnet flux-biased magnetic actuator with flux feedback

    Science.gov (United States)

    Groom, Nelson J. (Inventor)

    1991-01-01

    The invention is a permanent magnet flux-biased magnetic actuator with flux feedback for adjustably suspending an element on a single axis. The magnetic actuator includes a pair of opposing electromagnets and provides bi-directional forces along the single axis to the suspended element. Permanent magnets in flux feedback loops from the opposing electromagnets establish a reference permanent magnet flux-bias to linearize the force characteristics of the electromagnets to extend the linear range of the actuator without the need for continuous bias currents in the electromagnets.

  15. Dovetail spoke internal permanent magnet machine

    Science.gov (United States)

    Alexander, James Pellegrino; EL-Refaie, Ayman Mohamed Fawzi; Lokhandwalla, Murtuza; Shah, Manoj Ramprasad; VanDam, Jeremy Daniel

    2011-08-23

    An internal permanent magnet (IPM) machine is provided. The IPM machine includes a stator assembly and a stator core. The stator core also includes multiple stator teeth. The stator assembly is further configured with stator windings to generate a stator magnetic field when excited with alternating currents and extends along a longitudinal axis with an inner surface defining a cavity. The IPM machine also includes a rotor assembly and a rotor core. The rotor core is disposed inside the cavity and configured to rotate about the longitudinal axis. The rotor assembly further includes a shaft. The shaft further includes multiple protrusions alternately arranged relative to multiple bottom structures provided on the shaft. The rotor assembly also includes multiple stacks of laminations disposed on the protrusions and dovetailed circumferentially around the shaft. The rotor assembly further includes multiple pair of permanent magnets for generating a magnetic field, which magnetic field interacts with the stator magnetic field to produce a torque. The multiple pair of permanent magnets are disposed between the stacks. The rotor assembly also includes multiple middle wedges mounted between each pair of the multiple permanent magnets.

  16. Permanent Magnet Eddy Current Loss Analysis of a Novel Motor Integrated Permanent Magnet Gear

    DEFF Research Database (Denmark)

    Zhang, Yuqiu; Lu, Kaiyuan; Ye, Yunyue

    2012-01-01

    In this paper, a new motor integrated permanent magnet gear (MIPMG) is discussed. The focus is on eddy current loss analysis associated to permanent magnets (PMs). A convenient model of MIPMG is provided based on 2-D field-motion coupled time-stepping finite element method for transient eddy...

  17. High-temperature superconductors in high-field magnets

    NARCIS (Netherlands)

    Weijers, Hubertus Wilhelmus

    2009-01-01

    The properties of both BSCCO conductors and YBCO coated conductors and coils are studied to assess their applicability in high-field magnets. First, the magnetic field dependence of the critical current density in these HTS conductors is measured at 4.2 K in magnetic field conditions ranging from s

  18. Optimally segmented permanent magnet structures

    DEFF Research Database (Denmark)

    Insinga, Andrea Roberto; Bjørk, Rasmus; Smith, Anders

    2016-01-01

    We present an optimization approach which can be employed to calculate the globally optimal segmentation of a two-dimensional magnetic system into uniformly magnetized pieces. For each segment the algorithm calculates the optimal shape and the optimal direction of the remanent flux density vector...

  19. 永磁轨道上方高温超导块材各向异性对悬浮力弛豫特性的影响%INFLUENCE OF ANISOTROPY PROPERTY OF BULK HIGH TEMPERATURE SUPERCONDUCTOR ON LEVITATION RELAXATION PERFORMANCE ABOVE PERMANENT MAGNET GUIDEWAY

    Institute of Scientific and Technical Information of China (English)

    荆海莲; 郑珺; 廖兴林; 蒋冬辉; 林群煦; 王家素; 王素玉

    2012-01-01

    The melt-texturing processed bulk high temperature superconductor (HTSC) YBCO has five growth sections in each of the sample generally. By the trapped field experiments, it was known that the bulk HTSC shows the obvious anisotropy property. The capability of trapping fields of the bulk HTSC YBCO is different at each growth section and each boundary. Considering the application of the high temperature superconducting Maglev, the levitation relaxation performances of the different three-bulk HTSC arrays above the permanent magnet guideway (PMG) are discussed. According to the experimental results, the relaxation rate of levitation force show smaller if the crystal growth section boundary obeys the aligned growth section boundary arrangement (AGSBA) pattern rath- er than the misaligned growth section boundary arrangement (MGSBA) pattern, no matter at field cooling (FC) condition or zero field cooling (ZFC) condition. It implies the former levitation relaxation performance is better. The further study shows the relaxation rate of levitation force is smaller with the same pattern at the FC condition than that at the ZFC condition. The relaxation performance is better at the FC condition for the HTS Maglev application. It can be a good improvement option to arrange reasonably each onboard YBCO bulk position and the field cooling height for the better relaxation performance of the Maglev system as well as its better stability performance.%采用顶部熔融织构生长法制备的高温超导块材YBCO通常有5个生长区域.通过捕获磁通实验研究,人们发现高温超导块材内部生长区域及边界的捕获磁通能力不同,存在明显的各向异性.面向高温超导磁悬浮应用,本文比较研究了3块不同的高温超导块材YBCO组合在永磁轨道上方悬浮力弛豫特性.实验结果表明,无论场冷还是零场冷情况,块材籽晶生长线对齐排列方式的悬浮力衰减率均小于块材

  20. Design Study Of Cyclotron Magnet With Permanent Magnet

    Science.gov (United States)

    Kim, Hyun Wook; Chai, Jong Seo

    2011-06-01

    Low energy cyclotrons for Positron emission tomography (PET) have been wanted for the production of radio-isotopes after 2002. In the low energy cyclotron magnet design, increase of magnetic field between the poles is needed to make a smaller size of magnet and decrease power consumption. The Permanent magnet can support this work without additional electric power consumption in the cyclotron. In this paper the study of cyclotron magnet design using permanent magnet is shown and also the comparison between normal magnet and the magnet which is designed with permanent magnet is shown. Maximum energy of proton is 8 MeV and RF frequency is 79.3 MHz. 3D CAD design was done by CATIA P3 V5 R18 [1] and the All field calculations had been performed by OPERA-3D TOSCA [2]. The self-made beam dynamics program OPTICY [3] is used for making isochronous field and other calculations.

  1. Simulation and experiments of Stacks of High Temperature Superconducting Coated Conductors Magnetized by Pulsed Field Magnetization with Multi-Pulse Technique

    CERN Document Server

    Zou, Shengnan; Baskys, A; Patel, A; Grilli, Francesco; Glowacki, B A

    2016-01-01

    High temperature superconducting (HTS) bulks or stacks of coated conductors (CCs) can be magnetized to become trapped field magnets (TFMs). The magnetic fields of such TFMs can break the limitation of conventional magnets (<2 T), so they show potential for improving the performance of many electrical applications that use permanent magnets like rotating machines. Towards practical or commercial use of TFMs, effective in situ magnetization is one of the key issues. The pulsed field magnetization (PFM) is among the most promising magnetization methods in virtue of its compactness, mobility and low cost. However, due to the heat generation during the magnetization, the trapped field and flux acquired by PFM usually cannot achieve the full potential of a sample (acquired by the field cooling or zero field cooling method). The multi-pulse technique was found to effectively improve the trapped field by PFM in practice. In this work, a systematic study on the PFM with successive pulses is presented. A 2D electrom...

  2. Improvement of azimuthal homogeneity in permanent-magnet bearing rotors

    Science.gov (United States)

    Hull, J. R.; Rossing, T. D.; Mulcahy, T. M.; Uherka, K. L.

    1992-10-01

    Permanent magnets that are levitated and rotating over a bulk high-temperature superconductor (HTS) form the basis of many superconducting bearing designs. Experiments have shown that the rotational-loss 'coefficient of friction' for thrust bearings of this type can be as low as 8 x 10(exp -6). While the loss mechanisms of such bearings are not well understood, the azimuthal homogeneity of the rotating permanent magnet is believed to play an important role in determining the loss. One possible loss mechanism is magnetic hysteresis in the HTS, where the energy loss E per cycle is derived from the critical state model and given by E = K (Delta B)(sup 3)/J(sub c) where K is a geometric coefficient, Delta B is the variation in magnetic field at the surface of the HTS experienced during a rotation of the levitated magnet, and J(sub c) is the critical current density of the HTS. It is clear that a small decrease in Delta B (i.e., decreasing the azimuthal inhomogeneity of the rotating magnetic field) could have profound effects on decreasing E and the rotational coefficient of friction. The role of Delta B is also expected to be significant in reducing losses from eddy currents and other mechanisms. Low rotational losses in HTS bearings have been demonstrated only for levitated masses of several grams. For practical bearings, it is important to obtain these low losses with larger levitated masses. There are two main routes toward decreasing Delta B. The first is to improve the alignment of the magnetic particles during fabrication and to maintain close tolerances on grinding angles during manufacture of the permanent magnet. The second, the subject of this paper, is to provide correctional procedures after the magnet is fabricated.

  3. Hybrid high gradient permanent magnet quadrupole

    Science.gov (United States)

    N'gotta, P.; Le Bec, G.; Chavanne, J.

    2016-12-01

    This paper presents an innovative compact permanent magnet quadrupole with a strong gradient for potential use in future light source lattices. Its magnetic structure includes simple mechanical parts, rectangular permanent magnet blocks and soft iron poles. It has a wide aperture in the horizontal plane to accommodate an x-ray beam port, a common constraint in storage ring-based light sources. This specificity introduces field quality deterioration because of the resulting truncation of the poles; a suitable field quality can be restored with an optimized pole shape. A 82 T /m prototype with a bore radius of 12 mm and a 10 mm vertical gap between poles has been constructed and magnetically characterized. Gradient inhomogeneities better than 10-3 in the good field region were obtained after the installation of special shims.

  4. Permanent magnet motor technology design and applications

    CERN Document Server

    Gieras, Jacek F

    2009-01-01

    Demonstrates the construction of permanent magnet (PM) motor drives and supplies ready-to-implement solutions to common roadblocks along the way. This book also supplies fundamental equations and calculations for determining and evaluating system performance, efficiency, reliability, and cost. It explores modern computer-aided design of PM motors.

  5. Permanent Magnet Eddy Current Loss Analysis of a Novel Motor Integrated Permanent Magnet Gear

    DEFF Research Database (Denmark)

    Zhang, Yuqiu; Lu, Kaiyuan; Ye, Yunyue

    2012-01-01

    In this paper, a new motor integrated permanent magnet gear (MIPMG) is discussed. The focus is on eddy current loss analysis associated to permanent magnets (PMs). A convenient model of MIPMG is provided based on 2-D field-motion coupled time-stepping finite element method for transient eddy...... current analysis. The model takes the eddy current effect of PMs into account in determination of the magnetic field in the air-gap and in the magnet regions. The eddy current losses generated in the magnets are properly interpreted. Design improvements for reducing the eddy current losses are suggested...

  6. Experimental High Temperature Characterization of a Magnetic Bearing for Turbomachinery

    Science.gov (United States)

    Montague, Gerald; Jansen, Mark; Provenza, Andrew; Palazzolo, Alan; Jansen, Ralph; Ebihara, Ben

    2003-01-01

    Open loop, experimental force and power measurements of a radial, redundant-axis, magnetic bearing at temperatures to 1000 F (538 C) and rotor speeds to 15,000 RPM along with theoretical temperature and force models are presented in this paper. The experimentally measured force produced by a single C-core using 22A was 600 lb. (2.67 kN) at room temperature and 380 lb. (1.69 kN) at 1000 F (538 C). These values were compared with force predictions based on a 1D magnetic circuit analysis and a thermal analysis of gap growth as a function of temperature. Tests under rotating conditions showed that rotor speed has a negligible effect on the bearing s load capacity. One C-core required approximately 340 W of power to generate 190 lb. (8.45 kN) of magnetic force at 1000 F (538 C); however the magnetic air gap was much larger than at room temperature. The data presented is after the bearing had already operated six thermal cycles and eleven total (not consecutive) hours at 1000 F (538 C).

  7. Magnetic flux annihilation waves in inhomogeneous high-temperature superconductors

    NARCIS (Netherlands)

    Rudnev, IA; Khodot, AE; Eremin, AV; Mikhailov, BP

    2004-01-01

    The process of magnetic field penetration into polycrystalline high-T-c superconductors of the YBa2Cu3O7 - x and Bi2Sr2Ca2Cu3O10 - x systems has been studied using traditional magnetooptical methods and scanning Hall probe microscopy. It is established that remagnetization of a sample is accompanied

  8. Study of magnetic bearings with high temperature superconductors, phase 3

    Science.gov (United States)

    Eyssa, Y. M.; Huang, X.

    1991-01-01

    Three areas related to the actively controlled radial magnetic bearing concepts are discussed. These areas are: (1) modification to the ac loss calculations of the 1990 report; (2) a continuous changing mechanism to compensate rotor current drop due to ac losses; and (3) design of a proof of principle experiment simulating the proposed bearing concept.

  9. Practical Aspects of Modern and Future Permanent Magnets

    Science.gov (United States)

    McCallum, R. W.; Lewis, L.; Skomski, R.; Kramer, M. J.; Anderson, I. E.

    2014-07-01

    The mandate to reduce greenhouse gases will require highly efficient electric machines for both power generation and traction motor applications. Although permanent magnet electric machines utilizing Nd2Fe14B-based magnets provide obvious power-to-weight advantages over induction machines, the limited availability and high price of the rare earth (RE) metals make these machines less favorable. Of particular concern is the cost and supply criticality of Dy, a key RE element that is required to improve the high-temperature performance of Nd-based magnetic alloys for use in generators and traction motors. Alternatives to RE-based alloys do exist, but they currently lack the energy density necessary to replace Nd-based magnets. Many of these compounds have been known for decades, but serious interest in their development waned once compounds based on RE elements were discovered. In this review, intrinsic and extrinsic materials factors that impact the optimization of both existing and potential future permanent magnets for energy applications are examined in light of new insights gained from renewed examination.

  10. Sensorless Control of Permanent Magnet Synchronous Machines

    DEFF Research Database (Denmark)

    Matzen, Torben N.

    Permanent magnet machines, with either surface mounted or embedded magnets on the rotor, are becoming more common due to the key advantages of higher energy conversion efficiency and higher torque density compared to the classical induction machine. Besides energy efficiency the permanent magnet...... are dependent on the phase currents and rotor position. Based on the flux linkages the differential inductances are determined and used to establish the inductance saliency in terms of ratio and orientation. The orientation and its dependence on the current and rotor position are used to analyse the behaviour...... and establish the suitability of the machine for sensorless control using inductance saliency tracking methods. The same electromagnetic behaviour is used in the implementation of a dynamical simulation model of the machine useful for evaluation of sensorless control methods at the control design stage. Further...

  11. Simulations of magnetic hysteresis loops at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Plumer, M. L.; Whitehead, J. P.; Fal, T. J. [Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John' s, Newfoundland and Labrador A1B 3X7 (Canada); Ek, J. van [Western Digital Corporation, San Jose, California 94588 (United States); Mercer, J. I. [Department of Computer Science, Memorial University of Newfoundland, St. John' s, Newfoundland and Labrador A1B 3X7 (Canada)

    2014-09-28

    The kinetic Monte-Carlo algorithm as well as standard micromagnetics are used to simulate MH loops of high anisotropy magnetic recording media at both short and long time scales over a wide range of temperatures relevant to heat-assisted magnetic recording. Microscopic parameters, common to both methods, were determined by fitting to experimental data on single-layer FePt-based media that uses the Magneto-Optic Kerr effect with a slow sweep rate of 700 Oe/s. Saturation moment, uniaxial anisotropy, and exchange constants are given an intrinsic temperature dependence based on published atomistic simulations of FePt grains with an effective Curie temperature of 680 K. Our results show good agreement between micromagnetics and kinetic Monte Carlo results over a wide range of sweep rates. Loops at the slow experimental sweep rates are found to become more square-shaped, with an increasing slope, as temperature increases from 300 K. These effects also occur at higher sweep rates, typical of recording speeds, but are much less pronounced. These results demonstrate the need for accurate determination of intrinsic thermal properties of future recording media as input to micromagnetic models as well as the sensitivity of the switching behavior of thin magnetic films to applied field sweep rates at higher temperatures.

  12. Combinatorial investigation of rare-earth free permanent magnets

    Science.gov (United States)

    Fackler, Sean Wu

    The combinatorial high throughput method allows one to rapidly study a large number of samples with systematically changing parameters. We apply this method to study Fe-Co-V alloys as alternatives to rare-earth permanent magnets. Rare-earth permanent magnets derive their unmatched magnetic properties from the hybridization of Fe and Co with the f-orbitals of rare-earth elements, which have strong spin-orbit coupling. It is predicted that Fe and Co may also have strong hybridization with 4d and 5d refractory transition metals with strong spin-orbit coupling. Refractory transition metals like V also have the desirable property of high temperature stability, which is important for permanent magnet applications in traction motors. In this work, we focus on the role of crystal structure, composition, and secondary phases in the origin of competitive permanent magnetic properties of a particular Fe-Co-V alloy. Fe38Co52V10, compositions are known as Vicalloys. Fe-CoV composition spreads were sputtered onto three-inch silicon wafers and patterned into discrete sample pads forming a combinatorial library. We employed highthroughput screening methods using synchrotron X-rays, wavelength dispersive spectroscopy, and magneto-optical Kerr effect (MOKE) to rapidly screen crystal structure, composition, and magnetic properties, respectively. We found that in-plane magnetic coercive fields of our Vicalloy thin films agree with known bulk values (300 G), but found a remarkable eight times increase of the out-of-plane coercive fields (˜2,500 G). To explain this, we measured the switching fields between in-plane and out-of-plane thin film directions which revealed that the Kondorsky model of 180° domain wall reversal was responsible for Vicalloy's enhanced out-of-plane coercive field and possibly its permanent magnetic properties. The Kondorsky model suggests that domain-wall pinning is the origin of Vicalloy's permanent magnetic properties, in contrast to strain, shape, or

  13. Tunable high-gradient permanent magnet quadrupoles

    CERN Document Server

    Shepherd, B J A; Marks, N; Collomb, N A; Stokes, D G; Modena, M; Struik, M; Bartalesi, A

    2014-01-01

    A novel type of highly tunable permanent magnet (PM) based quadrupole has been designed by the ZEPTO collaboration. A prototype of the design (ZEPTO-Q1), intended to match the specification for the CLIC Drive Beam Decelerator, was built and magnetically measured at Daresbury Laboratory and CERN. The prototype utilises two pairs of PMs which move in opposite directions along a single vertical axis to produce a quadrupole gradient variable between 15 and 60 T/m. The prototype meets CLIC's challenging specification in terms of the strength and tunability of the magnet.

  14. Magnetic forces between arrays of cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, D.; Tomassetti, G.; Beleggia, Marco

    2011-01-01

    Permanent magnet arrays are often employed in a broad range of applications: actuators, sensors, drug targeting and delivery systems, fabrication of self-assembled particles, just to name a few. An estimate of the magnetic forces in play between arrays is required to control devices and fabrication...... procedures. Here, we introduce analytical expressions for calculating the attraction force between two arrays of cylindrical permanent magnets and compare the predictions with experimental data obtained from force measurements with NdFeB magnets. We show that the difference between predicted and measured...

  15. Dysprosium-free melt-spun permanent magnets.

    Science.gov (United States)

    Brown, D N; Wu, Z; He, F; Miller, D J; Herchenroeder, J W

    2014-02-12

    Melt-spun NdFeB powders can be formed into a number of different types of permanent magnet for a variety of applications in electronics, automotive and clean technology industries. The melt-spinning process produces flake powder with a fine uniform array of nanoscale Nd2Fe14B grains. These powders can be net-shape formed into isotropic polymer-bonded magnets or hot formed into fully dense magnets. This paper discusses the influence of heavy rare earth elements and microstructure on the magnetic performance, thermal stability and material cost of NdFeB magnets. Evidence indicates that melt-spun nanocrystalline NdFeB magnets are less dependent on heavy rare earth elements for high-temperature performance than the alternative coarser-grained sintered NdFeB magnets. In particular, hot-pressed melt-spun magnets are an attractive low-cost solution for applications that require thermal stability up to 175-200 °C.

  16. High temperature spin dynamics in linear magnetic chains, molecular rings, and segments by nuclear magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Adelnia, Fatemeh; Lascialfari, Alessandro [Dipartimento di Fisica, Università degli Studi di Milano and INSTM, Milano (Italy); Dipartimento di Fisica, Università degli Studi di Pavia and INSTM, Pavia (Italy); Mariani, Manuel [Dipartimento di Fisica e Astronomia, Università di Bologna, Bologna (Italy); Ammannato, Luca; Caneschi, Andrea; Rovai, Donella [Dipartimento di Chimica, Università degli Studi di Firenze and INSTM, Firenze (Italy); Winpenny, Richard; Timco, Grigore [School of Chemistry, The University of Manchester, Manchester (United Kingdom); Corti, Maurizio, E-mail: maurizio.corti@unipv.it; Borsa, Ferdinando [Dipartimento di Fisica, Università degli Studi di Pavia and INSTM, Pavia (Italy)

    2015-05-07

    We present the room temperature proton nuclear magnetic resonance (NMR) nuclear spin-lattice relaxation rate (NSLR) results in two 1D spin chains: the Heisenberg antiferromagnetic (AFM) Eu(hfac){sub 3}NITEt and the magnetically frustrated Gd(hfac){sub 3}NITEt. The NSLR as a function of external magnetic field can be interpreted very well in terms of high temperature spin dynamics dominated by a long time persistence of the decay of the two-spin correlation function due to the conservation of the total spin value for isotropic Heisenberg chains. The high temperature spin dynamics are also investigated in Heisenberg AFM molecular rings. In both Cr{sub 8} closed ring and in Cr{sub 7}Cd and Cr{sub 8}Zn open rings, i.e., model systems for a finite spin segment, an enhancement of the low frequency spectral density is found consistent with spin diffusion but the high cut-off frequency due to intermolecular anisotropic interactions prevents a detailed analysis of the spin diffusion regime.

  17. Robotized Surface Mounting of Permanent Magnets

    Directory of Open Access Journals (Sweden)

    Erik Hultman

    2014-10-01

    Full Text Available Using permanent magnets on a rotor can both simplify the design and increase the efficiency of electric machines compared to using electromagnets. A drawback, however, is the lack of existing automated assembly methods for large machines. This paper presents and motivates a method for robotized surface mounting of permanent magnets on electric machine rotors. The translator of the Uppsala University Wave Energy Converter generator is used as an example of a rotor. The robot cell layout, equipment design and assembly process are presented and validated through computer simulations and experiments with prototype equipment. A comparison with manual assembly indicates substantial cost savings and an improved work environment. By using the flexibility of industrial robots and a scalable equipment design, it is possible for this assembly method to be adjusted for other rotor geometries and sizes. Finally, there is a discussion on the work that remains to be done on improving and integrating the robot cell into a production line.

  18. A Novel Permanent Magnetic Angular Acceleration Sensor

    OpenAIRE

    Hao Zhao; Hao Feng

    2015-01-01

    Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating system, which enables convenient sensor installation. For the cup structure of the sensor rotor, it h...

  19. Axial flux permanent magnet brushless machines

    CERN Document Server

    Gieras, Jacek F; Kamper, Maarten J

    2008-01-01

    Axial Flux Permanent Magnet (AFPM) brushless machines are modern electrical machines with a lot of advantages over their conventional counterparts. They are being increasingly used in consumer electronics, public life, instrumentation and automation system, clinical engineering, industrial electromechanical drives, automobile manufacturing industry, electric and hybrid electric vehicles, marine vessels and toys. They are also used in more electric aircrafts and many other applications on larger scale. New applications have also emerged in distributed generation systems (wind turbine generators

  20. Didactic Considerations on Magnetic Circuits Excited by Permanent Magnets

    Science.gov (United States)

    Barmada, S.; Rizzo, R.; Sani, L.

    2009-01-01

    In this paper, the authors focus their attention on the way magnetic circuits and permanent magnets are usually treated in most textbooks and electrical engineering courses. This paper demonstrates how this important topic is too often presented simplistically. This simplistic treatment does not allow the students to develop a complete…

  1. Perspectives for high-performance permanent magnets: applications, coercivity, and new materials

    Science.gov (United States)

    Hirosawa, Satoshi; Nishino, Masamichi; Miyashita, Seiji

    2017-03-01

    High-performance permanent magnets are indispensable in the production of high-efficiency motors and generators and ultimately for sustaining the green earth. The central issue of modern permanent magnetism is to realize high coercivity near and above room temperature on marginally hard magnetic materials without relying upon the critical elements such as heavy rare earths by means of nanostructure engineering. Recent investigations based on advanced nanostructure analysis and large-scale first principles calculations have led to significant paradigm shifts in the understandings of coercivity mechanism in Nd–Fe–B permanent magnets, which includes the discovery of the ferromagnetism of the thin (2 nm) intergranular phase surrounding the Nd2Fe14B grains, the occurrence of negative (in-plane) magnetocrystalline anisotropy of Nd ions and some Fe atoms at the interface which degrades coercivity, and visualization of the stochastic behaviors of magnetization in the magnetization reversal process at high temperatures. A major change may occur also in the motor topologies, which is currently overwhelmed by the magnetic flux weakening interior permanent magnet motor type, to other types with variable flux permanent magnet type in some applications to open up a niche for new permanent magnet materials. Keynote talk at 8th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2016), 8–12 November 2016, Ha Long City, Vietnam.

  2. Forces between permanent magnets: experiments and model

    Science.gov (United States)

    González, Manuel I.

    2017-03-01

    This work describes a very simple, low-cost experimental setup designed for measuring the force between permanent magnets. The experiment consists of placing one of the magnets on a balance, attaching the other magnet to a vertical height gauge, aligning carefully both magnets and measuring the load on the balance as a function of the gauge reading. A theoretical model is proposed to compute the force, assuming uniform magnetisation and based on laws and techniques accessible to undergraduate students. A comparison between the model and the experimental results is made, and good agreement is found at all distances investigated. In particular, it is also found that the force behaves as r -4 at large distances, as expected.

  3. Dynamics of Permanent-Magnet Biased Active Magnetic Bearings

    Science.gov (United States)

    Fukata, Satoru; Yutani, Kazuyuki

    1996-01-01

    Active magnetic radial bearings are constructed with a combination of permanent magnets to provide bias forces and electromagnets to generate control forces for the reduction of cost and the operating energy consumption. Ring-shaped permanent magnets with axial magnetization are attached to a shaft and share their magnet stators with the electromagnets. The magnet cores are made of solid iron for simplicity. A simplified magnetic circuit of the combined magnet system is analyzed with linear circuit theory by approximating the characteristics of permanent magnets with a linear relation. A linearized dynamical model of the control force is presented with the first-order approximation of the effects of eddy currents. Frequency responses of the rotor motion to disturbance inputs and the motion for impulsive forces are tested in the non-rotating state. The frequency responses are compared with numerical results. The decay of rotor speed due to magnetic braking is examined. The experimental results and the presented linearized model are similar to those of the all-electromagnetic design.

  4. Developing a high-temperature superconducting bulk magnet for the maglev train of the future

    Science.gov (United States)

    Fujimoto, Hiroyuki

    1998-10-01

    The major applications of high-temperature superconductors have mostly been confined to products in the form of wires and thin films. However, recent developments show that rare-earth REBa2Cu3O7-x and light rare-earth LREBa2Cu3O7-3 superconductors prepared by melt processes have a high critical-current density at 77 K and high magnetic fields. These superconductors will promote the application of bulk high-temperature superconductors in high magnetic fields; the superconducting bulk magnet for the Maglev train is one possible application.

  5. Theoretical/Computational Studies of High-Temperature Superconductivity from Quantum Magnetism

    Science.gov (United States)

    2016-06-09

    AFRL-AFOSR-VA-TR-2016-0204 Theoretical/Computational Studies of High-Temperature Superconductivity from Quantum Magnetism Jose Rodriguez CALIFORNIA...TITLE AND SUBTITLE Theoretical/Computational Studies of High-Temperature Superconductivity from Quantum Magnetism 5a.  CONTRACT NUMBER 5b.  GRANT...SUBJECT TERMS quantum magnetism, HTS, superconductivity 16.  SECURITY CLASSIFICATION OF: 17.  LIMITATION OF       ABSTRACT UU 18.  NUMBER        OF

  6. Study on the Levitation and Restoring Force Characteristics of the Improved HTS-permanent Magnet Hybrid Magnetic Bearing

    Science.gov (United States)

    Sugiyama, R.; Oguni, K.; Ohashi, S.

    We have developed the hybrid magnetic bearing using permanent magnets and high temperature bulk super conductor (HTS). In this system, the permanent magnet has ring type structure so that the permanent magnet and the HTS can be set to the stator. The pinning force of the HTS is used for the levitation and the guidance. Repulsive force of the permanent magnets was used in the conventional hybrid system. However the restoring force in the guidance direction of the conventional hybrid system decreases by the side slip force of the permanent magnets. In this research, attractive force of permanent magnets is used for increasing the load weight in the guidance direction. In this paper, influence of the hybrid system on the static characteristics of the rotor is studied. Three-dimensional numerical analysis of the linkage flux (in the levitation and the guidance direction) in the HTS is undertaken. The stator side permanent magnet increases the linkage flux of the levitation direction. Therefore in the hybrid system the linkage flux of the levitation direction increases. The levitation and restoring force of the rotor is measured. The levitation force of the hybrid system becomes smaller than that of the non-hybrid one by attractive force. The rotor in the hybrid system is supported by the pinning force and attractive force. The restoring force of the hybrid system becomes larger than that of the non-hybrid one because of increasing the linkage flux of the levitation direction.

  7. Magnetic forces produced by rectangular permanent magnets in static microsystems.

    Science.gov (United States)

    Gassner, Anne-Laure; Abonnenc, Mélanie; Chen, Hong-Xu; Morandini, Jacques; Josserand, Jacques; Rossier, Joel S; Busnel, Jean-Marc; Girault, Hubert H

    2009-08-21

    Finite element numerical simulations were carried out in 2D geometries to map the magnetic field and force distribution produced by rectangular permanent magnets as a function of their size and position with respect to a microchannel. A single magnet, two magnets placed in attraction and in repulsion have been considered. The goal of this work is to show where magnetic beads are preferentially captured in a microchannel. These simulations were qualitatively corroborated, in one geometrical case, by microscopic visualizations of magnetic bead plug formation in a capillary. The results show that the number of plugs is configuration dependent with: in attraction, one plug in the middle of the magnets; in repulsion, two plugs near the edges of the magnets; and with a single magnet, a plug close to the center of the magnet. The geometry of the magnets (h and l are the height and length of the magnets respectively) and their relative spacing s has a significant impact on the magnetic flux density. Its value inside a magnet increases with the h/l ratio. Consequently, bar magnets produce larger and more uniform values than flat magnets. The l/s ratio also influences the magnetic force value in the microchannel, both increasing concomitantly for all the configurations. In addition, a zero force zone in the middle appears in the attraction configuration as the l/s ratio increases, while with a single magnet, the number of maxima and minima goes from one to two, producing two focusing zones instead of only one.

  8. Defective iron-oxide nanoparticles synthesised by high temperature plasma processing: a magnetic characterisation versus temperature

    Science.gov (United States)

    Balasubramanian, C.; Joseph, B.; Orpe, PB; Saini, NL; Mukherjee, S.; Dziedzic-Kocurek, K.; Stanek, J.; Di Gioacchino, D.; Marcelli, A.

    2016-11-01

    Magnetic properties and phase compositions of iron-oxide nanoparticles synthesised by a high temperature arc plasma route have been investigated by Mössbauer spectroscopy and high harmonic magnetic AC susceptibility measurements, and correlated with morphological and structural properties for different synthesis conditions. The Mössbauer spectra precisely determined the presence of different iron-oxide fractions in the investigated nanoparticles, while the high harmonic magnetic susceptibility measurements revealed the occurrence of metastable magnetic phases evolving in temperature and time. This study illustrates magnetic properties and dynamics of the magnetic configurations of iron-oxide nanoparticles grown by high temperature plasma, a process less explored so far but extremely useful for synthesising large numbers of nanoparticles for industrial applications.

  9. Design of magnet arrays for permanent magnetic linear motor

    Institute of Scientific and Technical Information of China (English)

    Junhong MAO; Junhang LUO; Qiang JIANG; Youbai XIE

    2008-01-01

    An iron-less single side permanent magnetic linear motor structure is presented,and two-dimensional analytical formulae for its magnetic field are deduced to design the types of magnetic arrays,the thickness of permanent magnet,and the duty ratio of magnet arrays,etc.With certain design parameters,conventional arrays are used instead of a piecewise Halbach arrays,and the machining and assembling of the motor are greatly simplified.Calculation results coincide with that of ANSYS.The analytical formulae can be used in designing cored linear motors by modifying boundary conditions.A linear motor driven bench with a single degree of freedom is realized,where the travel reaches 27 mm,the mass of the moving parts is 1.4 kg,and the maximum acceleration iS 11.5 m/s2.

  10. TEM observation of sintered permanent magnetic strontium ferrite

    Institute of Scientific and Technical Information of China (English)

    YU Hongya; LIU Zhengyi; ZENG Dechang

    2006-01-01

    Sintered permanent magnetic strontium ferrites were studied using transmission electron microscopy to investigate the microstructure morphology and its correlation with the magnetic properties. The present study shows that the microstructure of sintered permanent magnetic strontium ferrites is an important parameter in determining their magnetic properties. The microstructure morphology in low-performance ferrite magnet is obviously different from high-performance one. Themagnetic properties of sintered permanent strontium ferrite depend strongly on the orientation degree of strong magnetic crystals. The presence of ferric oxidephase in ferrite magnet can deteriorate the magnetic properties. Moreover, proper quantities of crystal defects are beneficial to high coercive force due to the fixing of magnetic domain.

  11. Performance of repulsive type magnetic bearing system under nonuniform magnetization of permanent magnet

    OpenAIRE

    Ohji, T.; Mukhopadhyay, S. C.; Iwahara, Masayoshi; Yamada, Sotoshi

    2000-01-01

    Permanent magnet bearing system utilizes the repulsive forces between the stator and rotor permanent magnets (PM) for the levitation of the system and it results a simplified axial control scheme. A repulsive type magnetic bearing system based on the above principle was fabricated in our laboratory. Material characteristics and the configuration of the permanent magnets are the central component for this type of bearing system. Due to aging or as both the magnets are repelling each other, the...

  12. Design of permanent magnetic solenoids for REGAE

    Energy Technology Data Exchange (ETDEWEB)

    Gehrke, Tim

    2013-10-15

    The Relativistic Electron Gun for Atomic Exploration (REGAE) is a small linear accelerator at DESY in Hamburg, which produces short, low emittance electron bunches. It is originally designed and built for ultrafast electron diffraction (UED) within the framework of the Center for Free-Electron Laser Science (CFEL). Additionally, two future experiments are planned at REGAE. First, an external injection experiment for Laser Wakefield Acceleration (LWA) will be performed in the framework of the LAOLA collaboration (LAboratory fOr Laser- and beam-driven plasma Acceleration). This experiment will provide a method for the reconstruction of the electric field distribution within a linear plasma wakefield. Second, a time resolving high energy Transmission Electron Microscope (TEM) will be implemented. Among others it is designed to allow for living cell imaging. Both experiments require strong focusing magnets inside the new target chamber at REGAE. Permanent magnetic solenoids (PMSs) can provide the needed focusing strength due to their enormous surface current density, while having compact dimensions at the same time. The present thesis deals with the design of such strong focusing PMSs. Since short and strong solenoids, as required for REGAE, exhibit a distinct non-linearity, the induced emittance growth is relatively large. This emittance growth is investigated and minimized for different set-ups with axially and radially magnetized annular magnets. Furthermore a magnetic shielding is developed. Together with a mechanical lifting system it assures that magnetic leakage fields do not disturb experiments, where the PMSs are removed from the beamline.

  13. Current status and future outlook for bonded neodymium permanent magnets (invited)

    Science.gov (United States)

    Croat, J. J.

    1997-04-01

    Bonded neodymium magnets can provide significant size and weight reduction and/or performance enhancement over sintered and, particularly, bonded ferrite permanent magnets and, moreover, provide these benefits at reasonable cost. Primarily for these reasons, these bonded magnets are now used in a wide and growing range of computer peripheral, office automation, and consumer electronic applications and now constitute the fastest growing segment of the permanent magnet market. The current status of these materials will be reviewed. Included is a brief overview of the manufacture of these magnetically isotropic magnets and a discussion of their unique properties and features from the perspective of both bonded magnet producer and user. Major applications are discussed as are some of the factors that will drive the market for these materials in the future. New technical developments, including the status and outlook for anisotropic bonded materials, high remanance isotropic materials and high temperature bonded magnets will also be discussed.

  14. Permanent magnetic toroidal drive with half stator

    Directory of Open Access Journals (Sweden)

    Lizhong Xu

    2017-01-01

    Full Text Available A permanent magnetic toroidal drive with a half stator is proposed that avoids noise and mechanical vibrations. The effects of the system parameters on the output torque of the drive were investigated. A model machine was designed and produced. The output torque and speed fluctuation of the drive system were measured, and the calculated and measured output torque were compared. The tests demonstrated that the drive system could operate continuously without noise, and the system achieved a given speed ratio. The drive system had high load-carrying ability and a maximum output torque of 0.15 N m when certain parameter values were used.

  15. Recent Advances on Permanent Magnet Machines

    Institute of Scientific and Technical Information of China (English)

    诸自强

    2012-01-01

    This paper overviews advances on permanent magnet(PM) brushless machines over last 30 years,with particular reference to new and novel machine topologies.These include current states and trends for surface-mounted and interior PM machines,electrically and mechanically adjusted variable flux PM machines including memory machine,hybrid PM machines which uniquely integrate PM technology into induction machines,switched and synchronous reluctance machines and wound field machines,Halbach PM machines,dual-rotor PM machines,and magnetically geared PM machines,etc.The paper highlights their features and applications to various market sectors.

  16. Strong permanent magnet-assisted electromagnetic undulator

    Science.gov (United States)

    Halbach, Klaus

    1988-01-01

    This invention discloses an improved undulator comprising a plurality of electromagnet poles located along opposite sides of a particle beam axis with alternate north and south poles on each side of the beam to cause the beam to wiggle or undulate as it travels generally along the beam axis and permanent magnets spaced adjacent the electromagnetic poles on each side of the axis of said particle beam in an orientation sufficient to reduce the saturation of the electromagnet poles whereby the field strength of the electromagnet poles can be increased beyond the normal saturation levels of the electromagnetic poles.

  17. Cerium: an unlikely replacement of dysprosium in high performance Nd-Fe-B permanent magnets.

    Science.gov (United States)

    Pathak, Arjun K; Khan, Mahmud; Gschneidner, Karl A; McCallum, Ralph W; Zhou, Lin; Sun, Kewei; Dennis, Kevin W; Zhou, Chen; Pinkerton, Frederick E; Kramer, Matthew J; Pecharsky, Vitalij K

    2015-04-24

    Replacement of Dy and substitution of Nd in NdFeB-based permanent magnets by Ce, the most abundant and lowest cost rare earth element, is important because Dy and Nd are costly and critical rare earth elements. The Ce, Co co-doped alloys have excellent high-temperature magnetic properties with an intrinsic coercivity being the highest known for T ≥ 453 K.

  18. Permanent superconducting magnets for space applications

    Science.gov (United States)

    Weinstein, Roy

    1994-01-01

    Work has been done to develop superconducting trapped field magnets (TFM's) and to apply them to a bumper-tether device for magnetic docking of spacecraft. The quality parameters for TFM's are J(c), the critical current of the superconductor, and d, the diameter of the superconducting tile. During this year we have doubled d, for production models, from 1 cm to 2 cm. This was done by means of seeding, an improved temperature profile in processing, and the addition of 1 percent Pt to the superconductor chemistry. Using these tiles we have set increasing records for the fields' permanent magnets. Magnets fabricated from old 1 cm tiles trapped 1.52 Tesla at 77K, 4.0T at 65K and 7.0T at 55K. The second of these fields broke a 17 year old record set at Stanford. The third field broke our own record. More recently using 2 cm tiles, we have trapped 2.3T at 77K, and 5.3T at 65K. We expect to trap lOT at 55K in this magnet in the near future. We have also achieved increases in J(c) using a method we developed for seeding U-235, and subsequently bombarding with neutrons. This method doubles J(c). We have not yet fabricated magnets from these tiles. During this year we have increased production yields from 15 percent to 95 percent. We have explored the properties of a magnetic bumper-tether for spacecraft. We have measured the bumper forces, and their dependence on time, distance, and the field of the ordinary ferromagnet (used together with a TFM). We have accounted for 85 percent of the collision energy, and its transformation to magnetic energy and heat energy. We have learned to control the relative bumper and tether forces by controlling TFM and ferromagnetic field strengths.

  19. Adjustable permanent magnet assembly for NMR and MRI

    Science.gov (United States)

    Pines, Alexander; Paulsen, Jeffrey; Bouchard, Louis S; Blumich, Bernhard

    2013-10-29

    System and methods for designing and using single-sided magnet assemblies for magnetic resonance imaging (MRI) are disclosed. The single-sided magnet assemblies can include an array of permanent magnets disposed at selected positions. At least one of the permanent magnets can be configured to rotate about an axis of rotation in the range of at least +/-10 degrees and can include a magnetization having a vector component perpendicular to the axis of rotation. The single-sided magnet assemblies can further include a magnet frame that is configured to hold the permanent magnets in place while allowing the at least one of the permanent magnets to rotate about the axis of rotation.

  20. Simulation on Magnetic Field Characteristics of Permanent-Magnet Seed-Metering Device

    OpenAIRE

    Wang, Jing; Hu, Jianping; Wang, Qirui; Wang, Xun

    2011-01-01

    Part 1: Simulation, Optimization, Monitoring and Control Technology; International audience; The cylindrical permanent magnet is the core part of the permanent-magnet seed-metering device, it can absorb single magnetic powder coated seed. The first, the magnetic induction intensity model of any point in the cylindrical permanent magnet external was established based on the equivalent current model of permanent magnet. The second, the mathematical formula was derived using the Biot-Savart law ...

  1. Forces between arrays of permanent magnets of basic geometric shapes

    DEFF Research Database (Denmark)

    Vokoun, D.; Beleggia, Marco

    2014-01-01

    We provide formulas for evaluating the magnetic force between two permanent magnet arrays, regularly spaced over a square lattice. We focus on three basic shapes of magnets constituting the arrays: cylinder, sphere and rectangular prism. When the lattice parameter is large, the expressions can...... be used to calculate the force between two single magnets in a computationally efficient way. The calculations are validated experimentally by measuring the attraction force between two single permanent magnets, where we demonstrate a fair agreement within about 15%....

  2. Advanced optimization of permanent magnet wigglers using a genetic algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Hajima, Ryoichi [Univ. of Tokyo (Japan)

    1995-12-31

    In permanent magnet wigglers, magnetic imperfection of each magnet piece causes field error. This field error can be reduced or compensated by sorting magnet pieces in proper order. We showed a genetic algorithm has good property for this sorting scheme. In this paper, this optimization scheme is applied to the case of permanent magnets which have errors in the direction of field. The result shows the genetic algorithm is superior to other algorithms.

  3. Main Problems Faced by Chinese RE Permanent Magnetic Industry

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Under over 50 years' development, Chinese rare earth magnetic industry developed into the global AINiCo, ferrite permanent magnets and NdFeB magnets manufacturing center, and average consumption of magnets per person in China increased to 1.026 tons in 2003 from 0.217 ton in 1990. Although China has been the large producing country of rare earth permanent magnetic materials, to be the strongest one, there are many problems to solve. Main Problems Faced By Chinese Permanent Magnet Industry

  4. Application of permanent magnets in accelerators and electron storage rings

    Science.gov (United States)

    Halbach, K.

    1985-04-01

    The use of permanent-magnet systems in high-energy accelerators and as sources of synchrotron radiation in electron-storage rings is discussed in a review of recent experimental investigations. Consideration is given to the generic advantages of permanent magnets over electromagnets (higher field strength per magnet size) in small-scale configurations; the magnetic properties of some charge-sheet-equivalent-permanent-magnet materials (CSEMs); and the design of pure-CSEM and CSEM-Fe-hybrid multipole magnetic lenses, dipoles, and undulator/wiggler systems for use in free-electron lasers and the production of elliptically polarized synchrotron light. Drawings and diagrams are provided.

  5. Magnetostatic interactions and forces between cylindrical permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Vokoun, David [Institute of Physics ASCR, v.v.i., Prague (Czech Republic)], E-mail: vokoun@fzu.cz; Beleggia, Marco [Institute for Materials Research, University of Leeds, Leeds LS2 9JT (United Kingdom); Heller, Ludek; Sittner, Petr [Institute of Physics ASCR, v.v.i., Prague (Czech Republic)

    2009-11-15

    Permanent magnets of various shapes are often utilized in magnetic actuators, sensors or releasable magnetic fasteners. Knowledge of the magnetic force is required to control devices reliably. Here, we introduce an analytical expression for calculating the attraction force between two cylindrical permanent magnets on the assumption of uniform magnetization. Although the assumption is not fulfilled exactly in cylindrical magnets, we obtain a very good agreement between the calculated and measured forces between two identical cylindrical magnets and within an array of NdFeB cylindrical magnets.

  6. Magnetostatic interactions and forces between cylindrical permanent magnets

    Science.gov (United States)

    Vokoun, David; Beleggia, Marco; Heller, Luděk; Šittner, Petr

    2009-11-01

    Permanent magnets of various shapes are often utilized in magnetic actuators, sensors or releasable magnetic fasteners. Knowledge of the magnetic force is required to control devices reliably. Here, we introduce an analytical expression for calculating the attraction force between two cylindrical permanent magnets on the assumption of uniform magnetization. Although the assumption is not fulfilled exactly in cylindrical magnets, we obtain a very good agreement between the calculated and measured forces between two identical cylindrical magnets and within an array of NdFeB cylindrical magnets.

  7. Magnetic Performance of a Nanocomposite Permanent Material

    Institute of Scientific and Technical Information of China (English)

    LIU Min; HAN Guang-Bing; GAO Ru-Wei

    2011-01-01

    @@ We build a sandwiched structure model in which the intergranular phase(IP) is homogeneously distributed between soft and hard magnetic grains, and gives a continuously anisotropic expression of the coupling part under the assumption that the IP weakens the intergrain exchange-coupling interaction.Based on the idea that the hardening mechanism is of the pinning type, we calculate the effect of the IP's thickness d and its anisotropy constant K1(0) on the intrinsic coercivity of a nanocomposite permanent material.The calculated results indicate that the domain wall goes twice through irreversible domain wall displacement during the process of moving from soft to hard magnetic grains, and the intrinsic coercivity increases with increasing d, but decreases with increasing K1(0).When d and K1(0) take 2nm and 0.7Kh, respectively, with Kh being the anisotropy constant in the inner part of the hard magnetic grain, the calculated intrinsic coercivity is in good agreement with the experimental data.

  8. Distributed generation induction and permanent magnet generators

    CERN Document Server

    Lai, L

    2007-01-01

    Distributed power generation is a technology that could help to enable efficient, renewable energy production both in the developed and developing world. It includes all use of small electric power generators, whether located on the utility system, at the site of a utility customer, or at an isolated site not connected to the power grid. Induction generators (IGs) are the cheapest and most commonly used technology, compatible with renewable energy resources. Permanent magnet (PM) generators have traditionally been avoided due to high fabrication costs; however, compared with IGs they are more reliable and productive. Distributed Generation thoroughly examines the principles, possibilities and limitations of creating energy with both IGs and PM generators. It takes an electrical engineering approach in the analysis and testing of these generators, and includes diagrams and extensive case study examples o better demonstrate how the integration of energy sources can be accomplished. The book also provides the ...

  9. Rotor for a line start permanent magnet machine

    Energy Technology Data Exchange (ETDEWEB)

    Melfi, Mike; Schiferl, Rich; Umans, Stephen

    2017-07-11

    A rotor comprises laminations with a plurality of rotor bar slots with an asymmetric arrangement about the rotor. The laminations also have magnet slots equiangularly spaced about the rotor. The magnet slots extend near to the rotor outer diameter and have permanent magnets disposed in the magnet slots creating magnetic poles. The magnet slots may be formed longer than the permanent magnets disposed in the magnets slots and define one or more magnet slot apertures. The permanent magnets define a number of poles and a pole pitch. The rotor bar slots are spaced from adjacent magnet slots by a distance that is at least 4% of the pole pitch. Conductive material is disposed in the rotor bar slots, and in some embodiments, may be disposed in the magnet slot apertures.

  10. Correlations Between Magnetic Flux and Levitation Force of HTS Bulk Above a Permanent Magnet Guideway

    Science.gov (United States)

    Huang, Huan; Zheng, Jun; Zheng, Botian; Qian, Nan; Li, Haitao; Li, Jipeng; Deng, Zigang

    2017-06-01

    In order to clarify the correlations between magnetic flux and levitation force of the high-temperature superconducting (HTS) bulk, we measured the magnetic flux density on bottom and top surfaces of a bulk superconductor while vertically moving above a permanent magnet guideway (PMG). The levitation force of the bulk superconductor was measured simultaneously. In this study, the HTS bulk was moved down and up for three times between field-cooling position and working position above the PMG, followed by a relaxation measurement of 300 s at the minimum height position. During the whole processes, the magnetic flux density and levitation force of the bulk superconductor were recorded and collected by a multipoint magnetic field measurement platform and a self-developed maglev measurement system, respectively. The magnetic flux density on the bottom surface reflected the induced field in the superconductor bulk, while on the top, it reveals the penetrated magnetic flux. The results show that the magnetic flux density and levitation force of the bulk superconductor are in direct correlation from the viewpoint of inner supercurrent. In general, this work is instructive for understanding the connection of the magnetic flux density, the inner current density and the levitation behavior of HTS bulk employed in a maglev system. Meanwhile, this magnetic flux density measurement method has enriched present experimental evaluation methods of maglev system.

  11. Bipolaron theory of the low magnetic field properties of high-temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrov, A.S.; Traven, S.V. (Moscow Engineering Physics Inst. (USSR))

    1991-02-01

    The low magnetic field properties of the layered high-temperature superconductors are studied in the frame of the two-dimensional heavy charged Bose-gas model. The temperature dependencies of the magnetic field penetration depth {lambda}{sub H}(T) and of the lower critical field H{sub c1}(T) are calculated in the London limit. The discrepancy between the temperature dependence of the penetration depth from the {mu}SR measurements and that from the ac susceptibility and magnetization measurements is discussed. (orig.).

  12. Study on control method of running velocity for the permanent magnet-HTSC hybrid magnetically levitated conveyance system

    Science.gov (United States)

    Nishio, R.; Ikeda, M.; Sasaki, R.; Ohashi, S.

    2011-11-01

    We have developed the magnetically levitated carrying system. In this system, pinning force of high temperature bulk super conductor (HTSC) is used for the levitation and guidance. Four HTSCs are installed on the carrier. The magnetic rail is set on the ground, and flux from the magnetic rail is pinned by HTSCs. To increase levitation force, repulsive force of the permanent magnet is used. The hybrid levitation system is composed. The permanent magnet is installed under the load stage of the carrier. Repulsive force by the permanent magnet between the load stage on the carrier and the magnetic rail on the ground is used to support the load weight. Levitation and guidance one by pinning effect of the YBaCuO HTSC in the carrier is used to levitate the carrier body. The load stage is separated from the carrier flame and can move freely for vertical direction levitation. For the propulsion system, electromagnet is installed on the surface of the magnetic rail. In this paper, control method of running velocity of the carrier is studied. Propulsion force is given as follows; Air core copper coils are installed on the magnetic rail. Interaction between current of these coils and permanent magnets on the carrier generates propulsion force. Running velocity is controlled by current of the propulsion coils. It is also changed by position of the carrier and the load weight. From the results, stability of the propulsion system is given, and propulsion characteristics are improved.

  13. Superconducting bulk magnet for maglev vehicle: Stable levitation performance above permanent magnet guideway

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Z.; Zheng, J.; Li, J.; Ma, G.; Lu, Y.; Zhang, Y.; Wang, S. [Applied Superconductivity Laboratory, Southwest Jiaotong University, Chengdu 610031 (China); Wang, J. [Applied Superconductivity Laboratory, Southwest Jiaotong University, Chengdu 610031 (China)], E-mail: jsywang@home.swjtu.edu.cn

    2008-06-15

    High-temperature superconducting (HTS) maglev vehicle is well known as one of the most potential applications of bulk high-temperature superconductors (HTSCs) in transported levitation system. Many efforts have promoted the practice of the HTS maglev vehicle in people's life by enhancing the load capability and stability. Besides improving the material performance of bulk HTSC and optimizing permanent magnet guideway (PMG), magnetization method of bulk HTSC is also very effective for more stable levitation. Up to now, applied onboard bulk HTSCs are directly magnetized by field cooling above the PMG for the present HTS maglev test vehicles or prototypes in China, Germany, Russia, Brazil, and Japan. By the direct-field-cooling-magnetization (DFCM) over PMG, maglev performances of the bulk HTSCs are mainly depended on the PMG's magnetic field. However, introducing HTS bulk magnet into the HTS maglev system breaks this dependence, which is magnetized by other non-PMG magnetic field. The feasibility of this HTS bulk magnet for maglev vehicle is investigated in the paper. The HTS bulk magnet is field-cooling magnetized by a Field Control Electromagnets Workbench (FCEW), which produces a constant magnetic field up to 1 T. The levitation and guidance forces of the HTS bulk magnet over PMG with different trapped flux at 15 mm working height (WH) were measured and compared with that by DFCM in the same applied PMG magnetic field at optimal field-cooling height (FCH) 30 mm, WH 15 mm. It is found that HTS bulk magnet can also realize a stable levitation above PMG. The trapped flux of HTS bulk magnet is easily controllable by the charging current of FCEW, which implies the maglev performances of HTS bulk magnet above PMG will be adjustable according to the practical requirement. The more trapped flux HTS bulk magnet will lead to bigger guidance force and smaller repulsion levitation force above PMG. In the case of saturated trapped flux for experimental HTS bulk

  14. Effect of Sm Volatilization on Magnetic Microstructures of Sintered Sm(Co,Fe,Cu,Zr)z Magnets at High Temperatures

    Institute of Scientific and Technical Information of China (English)

    XIA Ai-Lin; FANG Yi-Kun; GUO Zhao-Hui; LI Wei; HAN Bao-Shan

    2006-01-01

    @@ We present a magnetic force microscopy study of surface magnetic microstructure changes at high temperatures in 2:17-type Sm( Co, Fe, Cu,Zr)z (z ~ 7.4) magnets. Surface magnetic microstructures are found to change greatly in parallel and vertical specimens after heat-treatment at 400℃ for one hour in vacuum of 10-5 Torr with Ar gas as protecting atmosphere. Changes of microstructures are attributed to the formation of a soft-magnetic surfaces layer in the specimens, resulting from Sm volatilization due to high temperature. This hypothesis is further confirmed by the heat-treatment experiments at 400℃ for 0.5 h and 2 h. Finally, the existence of the soft-magnetic layers, which consist primarily of Fe-Co compounds, is verified by the results of both XRD and XPS of the vertical specimens before and after heat-treatment.

  15. Analysis of Permanent Magnets Bearings in Flywheel Rotor Designs

    Directory of Open Access Journals (Sweden)

    Prince Owusu-Ansah

    2016-04-01

    Full Text Available This paper discusses analysis of permanent magnet bearing in flywheel rotor designs. This work focuses on the advantages of using permanent magnets in flywheel rotor design as compared to that of the convectional mode of levitating the rotor position. The use of permanent magnet in magnetic bearing design to generate the steady state position of the magnetic field results in less variation of the force exerted on the rotor when it deviates from the nominal position than when an electrical coil is used for the same purpose. Theresults of the analysis shows that the magnetic bearing dynamics as well as its load carryingcapacity improves when the rotor is offset from its central position. The use of permanent magnet compared to current-carrying coils results in smaller overall size of magnetic bearing leading to a more compact system design resulting in improved rotordynamic performance

  16. Permanent magnet system to guide superparamagnetic particles

    Science.gov (United States)

    Baun, Olga; Blümler, Peter

    2017-10-01

    A new concept of using permanent magnet systems for guiding superparamagnetic nano-particles on arbitrary trajectories over a large volume is proposed. The basic idea is to use one magnet system which provides a strong, homogeneous, dipolar magnetic field to magnetize and orient the particles, and a second constantly graded, quadrupolar field, superimposed on the first, to generate a force on the oriented particles. In this configuration the motion of the particles is driven predominantly by the component of the gradient field which is parallel to the direction of the homogeneous field. As a result, particles are guided with constant force and in a single direction over the entire volume. The direction is simply adjusted by varying the angle between quadrupole and dipole. Since a single gradient is impossible due to Gauß' law, the other gradient component of the quadrupole determines the angular deviation of the force. However, the latter can be neglected if the homogeneous field is stronger than the local contribution of the quadrupole field. A possible realization of this idea is a coaxial arrangement of two Halbach cylinders. A dipole to evenly magnetize and orient the particles, and a quadrupole to generate the force. The local force was calculated analytically for this particular geometry and the directional limits were analyzed and discussed. A simple prototype was constructed to demonstrate the principle in two dimensions on several nano-particles of different size, which were moved along a rough square by manual adjustment of the force angle. The observed velocities of superparamagnetic particles in this prototype were always several orders of magnitude higher than the theoretically expected value. This discrepancy is attributed to the observed formation of long particle chains as a result of their polarization by the homogeneous field. The magnetic moment of such a chain is then the combination of that of its constituents, while its hydrodynamic radius

  17. Permanent magnet quadrupoles for the CLIC Drive Beam decelerator

    CERN Document Server

    Shepherd, Ben; Collomb, Norbert

    2012-01-01

    STFC in collaboration with CERN has developed a new type of adjustable permanent magnet based quadrupole for the CLIC Drive Beam Decelerator. It uses vertical movement of the permanent magnets to achieve an integrated gradient range of 3.6-14.6T, which will allow it to be used for the first 60% of the decelerator line. Construction of a prototype of this magnet has begun; following this, it will be measured magnetically at CERN and Daresbury Laboratory.

  18. A Novel Open-winding Permanent Magnetic Starter-generator

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In order to overcome the difficulties of voltage regulation, narrow speed range and low power factor of the traditional permanent magnetic generator applied in the vehicles, a novel open-winding permanent magnetic starter-generator (see Fig.l) is used to widen the speed range and improve the efficiency in the generation mode.

  19. Multifield measurement of magnetic fluctuation-induced particle flux in a high-temperature toroidal plasma

    Science.gov (United States)

    Lin, L.; Ding, W. X.; Brower, D. L.

    2016-12-01

    Magnetic fluctuation-induced particle transport is explored in the high-temperature, high-beta interior of the Madison symmetric torus (MST) reversed-field pinch by performing a multifield measurement of the correlated product of magnetic and density fluctuations associated with global resistive tearing modes. Local density fluctuations are obtained by inverting the line-integrated interferometry data after resolving the mode helicity through correlation techniques. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of Faraday-effect polarimetry measurements. Reconstructed 2D images of density and current density perturbations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particle transport flux and its spatial distribution are resolved. The convective magnetic fluctuation-induced particle flux profile is measured for both standard and high-performance plasmas in MST with tokamak-like confinement, showing large reduction in the flux during improved confinement.

  20. The 23 to 300 C demagnetization resistance of samarium-cobalt permanent magnets

    Science.gov (United States)

    Niedra, Janis M.; Overton, Eric

    1991-01-01

    The influence of temperature on knee point and squareness of the M-H demagnetization characteristic of permanent magnets is important information for the full utilization of the capabilities of samarium-cobalt magnets at high temperature in demagnetization resistent permanent magnet devices. Composite plots of the knee field and the demagnetizing field required to produce a given magnetic induction swing below remanence were obtained for several commercial Sm2Co17 type magnet samples in the temperature range of 23 to 300 C. Using the knee point to define the limits of operation safe against irreversible demagnetization, such plots are shown to provide an effective overview of the useable regions in the space of temperature-induction swing parameters. The observed second quadrant M-H characteristic squareness is shown, by two measures, to increase gradually with temperature, reaching a peak in the interval 200 to 300 C.

  1. A star role for stripes[Charge order in high-temperature superconductors in magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Tranquada, John [Physics Department, Brookhaven National Laboratory (United States)

    2002-06-01

    New images of magnetic and charge order in copper-oxide compounds are providing important clues about the nature of high-temperature superconductors. Visual images can have a powerful impact on the viewer, and this is certainly the case when the images are atomic-scale pictures of the surface of a high-temperature copper-oxide superconductor. The unusual properties of these materials have vexed condensed-matter theorists for the last 15 years. Now a new flurry of theoretical papers has been stimulated by the latest images of a cuprate superconductor, which reveal that an applied magnetic field can induce 'stripes' of charge. The experimental results provide intriguing and important clues to the nature of these ever-surprising materials - although the theorists have still to agree on their meaning. (U.K.)

  2. High Temperature Superconducting Magnets: Revolutionizing Next Generation Accelerators and Other Applications (466th Brookhaven Lecture)

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Ramesh (BNL Superconducting Magnet Division)

    2011-02-16

    BNL has always been a leader in the world of superconducting magnets, which are essential to the great modern ccelerators such as the Relativistic Heavy Ion Collider at BNL, or the Large Hadron Collider at CERN, Switzerland. These magnets are made of material that, cooled to 4 Kelvins (K) (-452° Farenheit) become superconducting, that is, lose essentially all resistance to electricity. For the past decade, however, Lab researchers have been exploring the use of new materials that become superconducting at higher temperatures. These materials can operate at the relatively high temperature of 77 K (-351°F), allowing them to be cooled by cheap, plentiful liquid nitrogen, rather than helium, and can create very high magnetic fields. Now far in the lead of this area of research, BNL scientists are exploring avenues for high temperature superconducting magnets that are energy efficient and have magnetic fields that are a million times stronger than the Earth’s. If successful, these new magnets could potentially revolutionize usage in future accelerators, play a key role in energy efficiency and storage, and make possible new applications such as muon colliders and MRI screening in remote areas.

  3. Permanent magnets in accelerators can save energy, space and cost

    DEFF Research Database (Denmark)

    Bødker, F.; Baandrup, L.O.; Hauge, N.

    2013-01-01

    Green Magnet® technology with close to zero electrical power consumption without the need for cooling water saves costs, space and natural resources. A compact dipole based on permanent magnets has been developed at Danfysik in collaboration with Sintex and Aarhus University. Our first Green Magnet...... coils permit fine tuning of the magnetic field. Magnetic field measurements and thermal stability tests show that the Green Magnet fully meets the magnetic requirements of the previously used electromagnet. A permanent 30° bending dipole is currently being development to demonstrate the use of Green...

  4. Three-dimensionality of field-induced magnetism in a high-temperature superconductor

    DEFF Research Database (Denmark)

    Lake, B.; Lefmann, K.; Christensen, N.B.

    2005-01-01

    insulators, where each copper spin is antiparallel to its nearest neighbours(1), evolves into a fluctuating state where the spins show tendencies towards magnetic order of a longer periodicity. For certain charge-carrier densities, quantum fluctuations are sufficiently suppressed to yield static long......Many physical properties of high-temperature superconductors are two-dimensional phenomena derived from their square-planar CuO(2) building blocks. This is especially true of the magnetism from the copper ions. As mobile charge carriers enter the CuO(2) layers, the antiferromagnetism of the parent...

  5. Review - X-ray diffraction measurements in high magnetic fields and at high temperatures

    Directory of Open Access Journals (Sweden)

    Yoshifuru Mitsui, Keiichi Koyama and Kazuo Watanabe

    2009-01-01

    Full Text Available A system was developed measuring x-ray powder diffraction in high magnetic fields up to 5 T and at temperatures from 283 to 473 K. The stability of the temperature is within 1 K over 6 h. In order to examine the ability of the system, the high-field x-ray diffraction measurements were carried out for Si and a Ni-based ferromagnetic shape-memory alloy. The results show that the x-ray powder diffraction measurements in high magnetic fields and at high temperatures are useful for materials research.

  6. High-Temperature Magnetic Bearings Being Developed for Gas Turbine Engines

    Science.gov (United States)

    Kascak, Albert F.

    1998-01-01

    Magnetic bearings are the subject of a new NASA Lewis Research Center and U.S. Army thrust with significant industry participation, and cooperation with other Government agencies. The NASA/Army emphasis is on high-temperature applications for future gas turbine engines. Magnetic bearings could increase the reliability and reduce the weight of these engines by eliminating the lubrication system. They could also increase the DN (diameter of bearing times the rpm) limit on engine speed and allow active vibration cancellation systems to be used, resulting in a more efficient, "more electric" engine. Finally, the Integrated High Performance Turbine Engine Technology (IHPTET) program, a joint Department of Defense/industry program, identified a need for a high-temperature (1200 F) magnetic bearing that could be demonstrated in their Phase III engine. This magnetic bearing is similar to an electric motor. It has a laminated rotor and stator made of cobalt steel. Wound around the stator's circumference are a series of electrical wire coils which form a series of electric magnets that exert a force on the rotor. A probe senses the position of the rotor, and a feedback controller keeps it centered in the cavity. The engine rotor, bearings, and casing form a flexible structure with many modes. The bearing feedback controller, which could cause some of these modes to become unstable, could be adapted to varying flight conditions to minimize seal clearances and monitor the health of the system.

  7. High temperature magnetism and microstructure of ferromagnetic alloy Si1-x Mn x

    Science.gov (United States)

    Aronzon, B. A.; Davydov, A. B.; Vasiliev, A. L.; Perov, N. S.; Novodvorsky, O. A.; Parshina, L. S.; Presniakov, M. Yu; Lahderanta, E.

    2017-02-01

    The results of a detailed study of magnetic properties and of the microstructure of SiMn films with a small deviation from stoichiometry are presented. The aim was to reveal the origin of the high temperature ferromagnetic ordering in such compounds. Unlike SiMn single crystals with the Curie temperature ~30 K, considered Si1-x Mn x compounds with x  =  0.5  +Δx and Δx in the range of 0.01-0.02 demonstrate a ferromagnetic state above room temperature. Such a ferromagnetic state can be explained by the existence of highly defective B20 SiMn nanocrystallites. These defects are Si vacancies, which are suggested to possess magnetic moments. The nanocrystallites interact with each other through paramagnons (magnetic fluctuations) inside a weakly magnetic manganese silicide matrix giving rise to a long range ferromagnetic percolation cluster. The studied structures with a higher value of Δx  ≈  0.05 contained three different magnetic phases: (a)—the low temperature ferromagnetic phase related to SiMn; (b)—the above mentioned high temperature phase with Curie temperature in the range of 200-300 K depending on the growth history and (c)—superparamagnetic phase formed by separated noninteracting SiMn nanocrystallites.

  8. Self propagating high temperature synthesis of metal oxides. Reactions in external magnetic fields

    CERN Document Server

    Aguas, M D

    2001-01-01

    The preparation of metal oxides by Self-Propagating High-Temperature Synthesis is reported. The reactions are started with a point source of ignition; typically a hot wire. A synthesis wave is observed moving out from the point source and reactions terminate in seconds. Products obtained can be classified into ferrites (magnetic applications) and stannates (gas sensing applications). Ferrites were synthesised under variable external magnetic fields. The synthesis wave is hotter in the presence of an external magnetic field for hard ferrite synthesis. For spinel ferrites the opposite was observed. Materials synthesised in the field show differences in their bulk magnetic properties (coercivity and saturation magnetisation), structures and microstructures. Combustion reactions in large fields revealed changes in unit cell volume (shrinkage was observed for hard ferrites while expansion was observed for spinel ferrites). SHS synthesised hard ferrites show two distinct components; one has large grain structure co...

  9. Status of high temperature superconductor based magnets and the conductors they depend upon

    CERN Document Server

    Schwartz, J; Chan, W K; Gou, X F; Liu, X T; Phillips, M; Le, Q V; Naderi, G; Turenne, M; Ye, L

    2011-01-01

    This paper reviews the status of high temperature superconductors for high field magnets for future devices such as a high energy LHC or a muon collider. Some of the primary challenges faced for the implementation of systems are discussed. Two conductor technologies, Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$ and YBa$_2$Cu$_3$O$_{7-\\delta}$, have emerged as high field conductor options, but their relative advantages and disadvantages for high field magnets are quite different. These are reviewed from an engineering perspective, including coil manufacturing, electromechanical behaviour and quench behaviour. Lastly, the important roles of "system pull" upon conductor and magnet technology development, and of interactions between the materials and magnet communities for accelerating development, are discussed.

  10. A note on magnetization of high temperature superconductors (YBCO, BSCCO) in mixed state

    Energy Technology Data Exchange (ETDEWEB)

    Kalta, B. [Department of Physics, Sonepur College, Subarnapur 767 017 (India); Pattanaik, A., E-mail: phyanup@gmail.com [P.G. Department of Physics, Sambalpur University, JV, Burla 768 019 (India); Nayak, P. [P.G. Department of Physics, Sambalpur University, JV, Burla 768 019 (India); Nanda, K.K. [Material Research Centre, Indian Institute of Sciences, Bangalore (India)

    2011-12-15

    Vortex overlapping has a prominent role in magnetism. M(H) shows linear dependence with vortex overlapping mechanism for YBCO compound. Magnetization in the reversible region. Effective penetration depth due to vortex overlapping. We present a critical study of the temperature and field dependence magnetization of high temperature superconductors (HTSCs). The controversial field dependence of dM/d ln B for YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) and Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} (BSCCO) is discussed using different models. Moreover, for both the systems the magnetization (M(H)) dependence is compared with field (H) dependence.

  11. Permanent magnets in accelerators can save energy, space and cost

    DEFF Research Database (Denmark)

    Bødker, F.; Baandrup, L.O.; Hauge, N.

    2013-01-01

    Green Magnet® technology with close to zero electrical power consumption without the need for cooling water saves costs, space and natural resources. A compact dipole based on permanent magnets has been developed at Danfysik in collaboration with Sintex and Aarhus University. Our first Green Magnet...... Magnet technology in other accelerator systems like synchrotron light sources and transfer beamlines....

  12. Remagnetization of bulk high-temperature superconductors subjected to crossed and rotating magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Vanderbemden, P [SUPRATECS and Department of Electrical Engineering and Computer Science B28, Sart-Tilman, B-4000 Liege (Belgium); Hong, Z [Centre for Advanced Photonics and Electronics, Engineering Department, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom); Coombs, T A [Centre for Advanced Photonics and Electronics, Engineering Department, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom); Ausloos, M [SUPRATECS and Department of Physics B5, Sart-Tilman, B-4000 Liege (Belgium); Babu, N Hari [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Cardwell, D A [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Campbell, A M [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom)

    2007-09-15

    Bulk melt-processed Y-Ba-Cu-O (YBCO) has significant potential for a variety of high-field permanent-magnet-like applications, such as the rotor of a brushless motor. When used in rotating devices of this kind, however, the YBCO can be subjected to both transient and alternating magnetic fields that are not parallel to the direction of magnetization and which have a detrimental effect on the trapped field. These effects may lead to long-term decay of the magnetization of the bulk sample. In the present work, we analyze both experimentally and numerically the remagnetization process of a melt-processed YBCO single domain that has been partially demagnetized by a magnetic field applied orthogonal to the initial direction of trapped flux. Magnetic torque measurements are used as a tool to probe changes in the remanent magnetization during various sequences of applied field. The application of a small magnetic field between the transverse cycles parallel to the direction of original magnetization results in partial remagnetization of the sample. Rotating the applied field, however, is found to be much more efficient at remagnetizing the bulk material than applying a magnetizing field pulse of the same amplitude. The principal features of the experimental data can be reproduced qualitatively using a two-dimensional finite-element numerical model based on an E-J power law. Finally, the remagnetization process is shown to result from the complex modification of current distribution within the cross-section of the bulk sample.

  13. Relativistic Engine Based on a Permanent Magnet

    CERN Document Server

    Tuval, Miron

    2015-01-01

    Newton's third law states that any action is countered by a reaction of equal magnitude but opposite direction. The total force in a system not affected by external forces is thus zero. However, according to the principles of relativity a signal can not propagate at speeds exceeding the speed of light. Hence the action cannot be generated at the same time with the reaction due to the relativity of simultaneity, thus the total force cannot be null at a given time. The following is a continuation of a previous paper \\cite{Tuval} in which we analyzed the relativistic effects in a system of two current conducting loops. Here the analysis is repeated but one of the loops is replaced by a permanent magnet. It should be emphasized that although momentum can be created in the {\\bf material} part of the system as described in the following work momentum can not be created in the {\\bf physical} system, hence for any momentum that is acquired by matter an opposite momentum is attributed to the electromagnetic field.

  14. A Novel Permanent Magnetic Angular Acceleration Sensor

    Directory of Open Access Journals (Sweden)

    Hao Zhao

    2015-07-01

    Full Text Available Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating system, which enables convenient sensor installation. For the cup structure of the sensor rotor, it has a relatively small rotational inertia. Due to the unique mechanical structure of the sensor, the output signal of the sensor can be directed without a slip ring, which avoids signal weakening effect. In this paper, the operating principle of the sensor is described, and simulated using finite element method. The sensitivity of the sensor is calibrated by torsional pendulum and angle sensor, yielding an experimental result of about 0.88 mV/(rad·s−2. Finally, the angular acceleration of the actual rotating system has been tested, using both a single-phase asynchronous motor and a step motor. Experimental result confirms the operating principle of the sensor and indicates that the sensor has good practicability.

  15. From permanent magnets to rechargeable hydride electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Willems, J.J.G.; Buschow, K.H.J.

    1987-02-15

    A brief historical survey is given of how the study of coercitivity mechanisms in SmCo/sub 5/ permanent-magnet materials eventually led to the discovery of the favourable hydrogen sorption properties of the compound LaNi/sub 5/. It is shown how continued research by many investigators dealing with a variety of different physical and chemical properties has resulted in an advanced understanding of some of the principles that govern hydrogen absorption and which are responsible for the changes in physical properties that accompany it. The problems associated with various applications of LaNi/sub 5/-based hydrogen-storage materials are also briefly discussed. A large part of this paper is devoted to the applicability of LaNi/sub 5/-type materials in batteries. Research in this area has resulted in the development of a new type of rechargeable battery: the nickel-hydride cell. This battery can be charged and discharged at high rates and is relatively insensitive to overcharging and overdischarging. Special attention is given to the nature of the electrode degradation process and the effect of composition variations in LaNi/sub 5/-related materials on the lifetime of the corresponding hydride electrodes when subjected to severe electrochemical charge-discharge cycles.

  16. A Novel Permanent Magnetic Angular Acceleration Sensor.

    Science.gov (United States)

    Zhao, Hao; Feng, Hao

    2015-07-03

    Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating system, which enables convenient sensor installation. For the cup structure of the sensor rotor, it has a relatively small rotational inertia. Due to the unique mechanical structure of the sensor, the output signal of the sensor can be directed without a slip ring, which avoids signal weakening effect. In this paper, the operating principle of the sensor is described, and simulated using finite element method. The sensitivity of the sensor is calibrated by torsional pendulum and angle sensor, yielding an experimental result of about 0.88 mV/(rad·s(-2)). Finally, the angular acceleration of the actual rotating system has been tested, using both a single-phase asynchronous motor and a step motor. Experimental result confirms the operating principle of the sensor and indicates that the sensor has good practicability.

  17. Efficient IEC permanent magnet motor; Effizienter IEC Permanent-Magnetmotor (3 kW) - Jahresbericht 2007

    Energy Technology Data Exchange (ETDEWEB)

    Lindegger, M.; Salathe, D.; Biner, H. P.; Evequoz, B.

    2007-07-01

    This annual report for the Swiss Federal Office of Energy (SFOE) takes a look at the work done at the Swiss Universities of Applied Sciences in Lucerne and Valais and the Circle Motor Company in 2007 on the economic feasibility, efficiency and limitations of permanent magnet motors. The higher efficiency of permanent-magnet motors in comparison with asynchronous motors for powers of over 100 kW is noted. Work done on the integration of a 3 kW permanent-magnet motor in an IEC-Standard housing is described. The construction of an efficient permanent magnet motor drive and its testing at the Valais University of Applied Sciences is discussed. The high efficiencies obtained both for the motor and its drive electronics are noted.

  18. Research on Magnetic Model of Low Resistance Permanent Magnet Pipe Belt Conveyor

    Science.gov (United States)

    Wang, Shuang; Li, De-yong; Guo, Yong-cun

    2016-09-01

    In view of the feasibility of a new type of low resistance permanent magnet pipe belt conveyor, the magnetic properties of the permanent magnet magnetic pipe conveyor belt system are studied. Based on the molecular current hypothesis, the mathematical model of the three dimensional radial magnetic force of permanent magnet pipe conveyor belt was established. The mathematical model of the radial magnetic force was derived, and the influence factors of the radial magnetic force were derived. The finite element simulation of permanent magnet-magnetic pipe conveyor belt magnetic model was carried out, then the magnetic flux density distribution chart under the conditions of different remanence intensity of different permanent magnet and different lengths of the permanent magnets (along the transport direction) were obtained. The simulation results are consistent with the calculation results, which shows that the permanent magnet pipe belt conveyor is feasible. Under certain conditions, the radial magnetic force has nonlinear increase relations with residual magnetism of permanent magnet and the length of the permanent magnet (along the transport direction).

  19. Globally Optimal Segmentation of Permanent-Magnet Systems

    DEFF Research Database (Denmark)

    Insinga, Andrea Roberto; Bjørk, Rasmus; Smith, Anders

    2016-01-01

    Permanent-magnet systems are widely used for generation of magnetic fields with specific properties. The reciprocity theorem, an energy-equivalence principle in magnetostatics, can be employed to calculate the optimal remanent flux density of the permanent-magnet system, given any objective...... functional that is linear in the magnetic field. This approach, however, yields a continuously varying remanent flux density, while in practical applications, magnetic assemblies are realized by combining uniformly magnetized segments. The problem of determining the optimal shape of each of these segments...

  20. Permanent magnet microstructures using dry-pressed magnetic powders

    Science.gov (United States)

    Oniku, Ololade D.; Bowers, Benjamin J.; Shetye, Sheetal B.; Wang, Naigang; Arnold, David P.

    2013-07-01

    This paper presents microfabrication methods and performance analysis of bonded powder permanent magnets targeting dimensions ranging from 10 µm to greater than 1 mm. For the structural definition and pattern transfer, a doctor blade technique is used to dry press magnetic powders into pre-etched cavities in a silicon substrate. The powders are secured in the cavities by one of the three methods: capping with a polyimide layer, thermal reflow of intermixed wax-binder particles, or conformal coating with a vapor-deposited parylene-C film. A systematic study of micromagnets fabricated using these methods is conducted using three different types of magnetic powders: 50 µm Nd-Fe-B, 5 µm Nd-Fe-B and 1 µm barium ferrite powder. The isotropic magnets are shown to exhibit intrinsic coercivities (Hci) as high as 720 kA m-1, remanences (Br) up to 0.5 T and maximum energy products (BHmax) up to 30 kJ m-3, depending on the magnetic powder used. Process compatibility experiments demonstrate the potential for the magnets to withstand typical microfabrication chemical exposure and thermal cycles, thereby facilitating their integration into more complex process flows. The remanences are also characterized at elevated temperatures to determine thermal sensitivities and maximum operating temperature ranges.

  1. Magnetic Signals of High-Temperature Superconductor Bulk During the Levitation Force Measurement Process

    Science.gov (United States)

    Huang, Huan; Zheng, Jun; Qian, Nan; Che, Tong; Zheng, Botian; Jin, Liwei; Deng, Zigang

    2017-05-01

    In order to study the commonly neglected magnetic field information in the course of levitation force measurement process in a superconducting maglev system, a multipoint magnetic field measurement platform was employed to acquire magnetic signals of a bulk high-Tc superconductor on both the top and the bottom surface. Working conditions including field cooling (FC) and zero field cooling were investigated for these vertical down and up motions above a permanent magnet guideway performed on a HTS maglev measurement system. We have discussed the magnetic flux variation process based on the Bean model. A magnetic hysteresis effect similar to the levitation force hysteresis loop of the bulk superconductor was displayed and analyzed in this paper. What is more valuable, there exists some available magnetic flux on the top surface of the bulk superconductor, and the proportion is as high as 62.42% in the FC condition, which provides an experimental hint to design the superconductor bulk and the applied field for practical use in a more efficient way. In particular, this work reveals real-time magnetic flux variation of the bulk superconductor in the levitation application, which is the other important information in contrast to the macroscopic levitation and guidance force investigations in previous studies, and it enriches the existing research methods. The results are significant for understanding the magnetic characteristic of superconductors, and they can contribute to optimize the present HTS maglev system design.

  2. Magnetic Signals of High-Temperature Superconductor Bulk During the Levitation Force Measurement Process

    Science.gov (United States)

    Huang, Huan; Zheng, Jun; Qian, Nan; Che, Tong; Zheng, Botian; Jin, Liwei; Deng, Zigang

    2017-02-01

    In order to study the commonly neglected magnetic field information in the course of levitation force measurement process in a superconducting maglev system, a multipoint magnetic field measurement platform was employed to acquire magnetic signals of a bulk high-Tc superconductor on both the top and the bottom surface. Working conditions including field cooling (FC) and zero field cooling were investigated for these vertical down and up motions above a permanent magnet guideway performed on a HTS maglev measurement system. We have discussed the magnetic flux variation process based on the Bean model. A magnetic hysteresis effect similar to the levitation force hysteresis loop of the bulk superconductor was displayed and analyzed in this paper. What is more valuable, there exists some available magnetic flux on the top surface of the bulk superconductor, and the proportion is as high as 62.42% in the FC condition, which provides an experimental hint to design the superconductor bulk and the applied field for practical use in a more efficient way. In particular, this work reveals real-time magnetic flux variation of the bulk superconductor in the levitation application, which is the other important information in contrast to the macroscopic levitation and guidance force investigations in previous studies, and it enriches the existing research methods. The results are significant for understanding the magnetic characteristic of superconductors, and they can contribute to optimize the present HTS maglev system design.

  3. Iron free permanent magnet systems for charged particle beam optics

    Energy Technology Data Exchange (ETDEWEB)

    Lund, S.M.; Halbach, K.

    1995-09-03

    The strength and astounding simplicity of certain permanent magnet materials allow a wide variety of simple, compact configurations of high field strength and quality multipole magnets. Here we analyze the important class of iron-free permanent magnet systems for charged particle beam optics. The theory of conventional segmented multipole magnets formed from uniformly magnetized block magnets placed in regular arrays about a circular magnet aperture is reviewed. Practical multipole configurations resulting are presented that are capable of high and intermediate aperture field strengths. A new class of elliptical aperture magnets is presented within a model with continuously varying magnetization angle. Segmented versions of these magnets promise practical high field dipole and quadrupole magnets with an increased range of applicability.

  4. Magnetic nanostructuring and overcoming Brown's paradox to realize extraordinary high-temperature energy products

    Science.gov (United States)

    Balasubramanian, Balamurugan; Mukherjee, Pinaki; Skomski, Ralph; Manchanda, Priyanka; Das, Bhaskar; Sellmyer, David J.

    2014-09-01

    Nanoscience has been one of the outstanding driving forces in technology recently, arguably more so in magnetism than in any other branch of science and technology. Due to nanoscale bit size, a single computer hard disk is now able to store the text of 3,000,000 average-size books, and today's high-performance permanent magnets--found in hybrid cars, wind turbines, and disk drives--are nanostructured to a large degree. The nanostructures ideally are designed from Co- and Fe-rich building blocks without critical rare-earth elements, and often are required to exhibit high coercivity and magnetization at elevated temperatures of typically up to 180 °C for many important permanent-magnet applications. Here we achieve this goal in exchange-coupled hard-soft composite films by effective nanostructuring of high-anisotropy HfCo7 nanoparticles with a high-magnetization Fe65Co35 phase. An analysis based on a model structure shows that the soft-phase addition improves the performance of the hard-magnetic material by mitigating Brown's paradox in magnetism, a substantial reduction of coercivity from the anisotropy field. The nanostructures exhibit a high room-temperature energy product of about 20.3 MGOe (161.5 kJ/m3), which is a record for a rare earth- or Pt-free magnetic material and retain values as high as 17.1 MGOe (136.1 kJ/m3) at 180°C.

  5. Magnetic nanostructuring and overcoming Brown's paradox to realize extraordinary high-temperature energy products.

    Science.gov (United States)

    Balasubramanian, Balamurugan; Mukherjee, Pinaki; Skomski, Ralph; Manchanda, Priyanka; Das, Bhaskar; Sellmyer, David J

    2014-09-02

    Nanoscience has been one of the outstanding driving forces in technology recently, arguably more so in magnetism than in any other branch of science and technology. Due to nanoscale bit size, a single computer hard disk is now able to store the text of 3,000,000 average-size books, and today's high-performance permanent magnets--found in hybrid cars, wind turbines, and disk drives--are nanostructured to a large degree. The nanostructures ideally are designed from Co- and Fe-rich building blocks without critical rare-earth elements, and often are required to exhibit high coercivity and magnetization at elevated temperatures of typically up to 180 °C for many important permanent-magnet applications. Here we achieve this goal in exchange-coupled hard-soft composite films by effective nanostructuring of high-anisotropy HfCo7 nanoparticles with a high-magnetization Fe65Co35 phase. An analysis based on a model structure shows that the soft-phase addition improves the performance of the hard-magnetic material by mitigating Brown's paradox in magnetism, a substantial reduction of coercivity from the anisotropy field. The nanostructures exhibit a high room-temperature energy product of about 20.3 MGOe (161.5 kJ/m(3)), which is a record for a rare earth- or Pt-free magnetic material and retain values as high as 17.1 MGOe (136.1 kJ/m(3)) at 180°C.

  6. 2000 Lilienfeld Prize Talk - From Model Magnets to High Temperature Superconductors

    Science.gov (United States)

    Birgeneau, Robert J.

    2000-03-01

    Magnetic materials often provide simple and clean examples of important problems in statistical physics. In recent years, much attention has been focussed on one and two dimensional Heisenberg spin systems in which quantum fluctuations play an essential role. Of particular interest are the two dimensional CuO2 Heisenberg square lattice antiferromagnets which, on doping with holes or electrons, become high temperature superconductors. We will review the results of experiments and quantum Monte Carlo calculations on one and two dimensional quantum magnets. We shall also discuss recent neutron studies of the novel incommensurate magnetic structures that occur in the spin glass and superconducting phases of the doped La2CuO4 system. We shall emphasize, in particular, the newly discovered one dimensional spin modulations in the spin glass phase together with the reorientation transition which coincides with the insulator to superconducting transition.

  7. Fracture in sintered Sm-Co permanent magnetic materials

    Institute of Scientific and Technical Information of China (English)

    LI; Anhua(李安华); DONG; Shengzhi(董生智); LI; Wei(李卫)

    2003-01-01

    The bending strength and fracture toughness of sintered Sm-Co permanent magnetic materials are measured. A scanning electron microscope equipped with an energy dispersive X-ray analysis system is employed to investigate the bending fractography. The fracture behavior and micromechanism are discussed. The fracture behavior of sintered Sm-Co permanent magnetic materials exhibits cleavage fracture. Some Sm-rich impurities are found in fracture plane, suggesting that the Sm-rich impurities help reduce the cleavage brittleness of sintered Sm-Co permanent magnetic materials. The possible methods for improving the strength and toughness are also proposed.

  8. High temperature radio-frequency superconducting quantum interference device system for detection of magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Pretzell, Alf

    2012-07-01

    This doctoral thesis was aimed at establishing a set-up with high-temperature superconductor (HTS) radio-frequency (rf) superconducting quantum interference device (SQUID) technology for the detection of magnetic nanoparticles and in particular for testing applications of magnetic nanoparticle immunoassays. It was part of the EU-project ''Biodiagnostics'' running from 2005 to 2008. The method of magnetic binding assays was developed as an alternative to other methods of concentration determination like enzyme linked immunosorbent assay (ELISA), or fluorescent immunoassay. The ELISA has sensitivities down to analyte-concentrations of pg/ml. Multiple incubation and washing steps have to be performed for these techniques, the analyte has to diffuse to the site of binding. The magnetic assay uses magnetic nanoparticles as markers for the substance to be detected. It is being explored by current research and shows similar sensitivity compared to ELISA but in contrast - does not need any washing and can be read out directly after binding - can be applied in solution with opaque media, e.g. blood or muddy water - additionally allows magnetic separation or concentration - in combination with small magnetoresistive or Hall sensors, allows detection of only a few particles or even single beads. For medical or environmental samples, maybe opaque and containing a multitude of substances, it would be advantageous to devise an instrument, which allows to be read out quickly and with high sensitivity. Due to the mentioned items the magnetic assay might be a possibility here.

  9. Spin-lattice coupling induced weak dynamical magnetism in EuTiO3 at high temperatures

    Science.gov (United States)

    Guguchia, Z.; Keller, H.; Kremer, R. K.; Köhler, J.; Luetkens, H.; Goko, T.; Amato, A.; Bussmann-Holder, A.

    2014-08-01

    EuTiO3, which is a G-type antiferromagnet below TN=5.5 K, has some fascinating properties at high temperatures, suggesting that macroscopically hidden dynamically fluctuating weak magnetism exists at high temperatures. This conjecture is substantiated by magnetic field dependent magnetization measurements, which exhibit pronounced anomalies below 200 K becoming more distinctive with increasing magnetic field strength. Additional results from muon spin rotation experiments provide evidence for weak fluctuating bulk magnetism induced by spin-lattice coupling which is strongly supported in increasing magnetic field.

  10. Multipactor Mitigation in Coaxial Lines by Means of Permanent Magnets

    CERN Document Server

    Gonzalez-Iglesias, D; Anza, S; Vague, J; Gimeno, B; Boria, V E; Raboso, D; Vicente, C; Gil, J; Caspers, F; Conde, L

    2014-01-01

    The main aim of this paper is the analysis of the feasibility of employing permanent magnets for the multipactor mitigation in a coaxial waveguide. First, the study of a coaxial line immersed in a uniform axial magnetic field shows that multipactor can be suppressed at any RF frequency if the external magnetic field is strong enough. Both theoretical simulations and experimental tests validate this statement. Next, multipactor breakdown of a coaxial line immersed in a hollow cylindrical permanent magnet is analyzed. Numerical simulations show that multipactor can be suppressed in a certain RF frequency range. The performed experimental test campaign demonstrates the capability of the magnet to avoid the multipactor electron multiplication process.

  11. Characterization of magnetic biochar amended with silicon dioxide prepared at high temperature calcination

    Directory of Open Access Journals (Sweden)

    Baig Shams Ali

    2016-09-01

    Full Text Available Calcination is considered to increase the hardness of composite material and prevent its breakage for the effective applications in environmental remediation. In this study, magnetic biochar amended with silicon dioxide was calcined at high temperature under nitrogen environment and characterized using various techniques. X-ray diffraction (XRD analysis revealed elimination of Fe3O4 peaks under nitrogen calcination and formation of Fe3Si and iron as major constituents of magnetic biochar-SiO2 composite, which demonstrated its superparamagnetic behavior (>80 A2·kg−1 comparable to magnetic biochar. Thermogravimetric analysis (TGA revealed that both calcined samples generated higher residual mass (>96 % and demonstrated better thermal stability. The presence of various bands in Fourier transform infrared spectroscopy (FT-IR was more obvious and the elimination of H–O–H bonding was observed at high temperature calcination. In addition, scanning electron microscopy (SEM images revealed certain morphological variation among the samples and the presence of more prominent internal and external pores, which then judged the surface area and pore volume of samples. Findings from this study suggests that the selective calcination process could cause useful changes in the material composites and can be effectively employed in environmental remediation measures.

  12. Characterisation of practical high temperature superconductors in pulsed magnetic fields and development of associated technology

    CERN Document Server

    Saleh, P M

    2000-01-01

    including a innovative design of a 100ms pulsed magnet solenoid. Critical current measurements on state of the art practical high temperature superconductors are presented. Bi sub 2 Sr sub 2 CaCu sub 2 O silver-alloy matrix powder-in-tube and silver-alloy substrate dip-coated tapes, formed into various geometries, have been tested in pulsed magnetic fields of various pulse lengths. These measurements have been compared to tests performed in continuous magnetic fields. A distinct discrepancy between pulsed and continuous measurements has been observed in these silver-alloy, high temperature superconductor composites. The critical current measured in pulsed fields is depressed compared to those measured in continuous fields. Evidence is provided to strongly suggest that eddy current heating in the silver-alloy substrate/sheath of the conductor is responsible for this discrepancy. A model is presented to predict the temperature rise due to eddy current heating. This model shows good agreement with observations. ...

  13. Porous cobalt spheres for high temperature gradient magnetically assisted fluidized beds

    Science.gov (United States)

    Atwater, James E.; Akse, James R.; Jovanovic, Goran N.; Wheeler, Richard R Jr; Sornchamni, Thana

    2003-01-01

    Porous metallic cobalt spheres have been prepared as high temperature capable media for employment in gradient magnetically assisted fluidization and filtration technologies. Cobalt impregnated alginate beads are first formed by extrusion of an aqueous suspension of Co3O4 into a Co(II) chloride solution. The organic polymer is thermally decomposed yielding cobalt oxide spheres, followed by reduction to the metallic state, and densification. Cobalt beads have been produced with porosities ranging between 10 and 50%, depending upon sintering conditions. The product media have been characterized by scanning electron microscopy (SEM), nitrogen adsorption porosimetry, and vibrating sample magnetometry. c2003 Elsevier Science Ltd. All rights reserved.

  14. Anisotropy Effect on Levitation Performance of Bulk High-Tc Superconductors Above a Permanent Magnet Guideway

    Science.gov (United States)

    Zheng, Jun; Liao, Xinglin; Jing, Hailian; Lin, Qunxu; Ma, Guangtong; Yen, Fei; Wang, Suyu; Wang, Jiasu

    The anisotropy properties of bulk high-temperature superconductors (HTSCs) are taken into consideration for the application of high-temperature superconducting (HTS) Maglev systems, which are especially based on the different flux-trapping capabilities as well as critical current density, Jc, values between the growth section boundary (GSB) and the growth sections (GS) in bulk superconductors. By adjusting the angle between the GSB of bulk HTSCs and the strongest magnetic field position of a permanent magnet guideway (PMG), the levitation force and its relaxation processes are compared at different field-cooling conditions. Experimental results show that the levitation capability and the suppression of levitation force decay can be enhanced by optimizing the GS/GSB alignment of every bulk HTSC above the PMG. Meanwhile, our conclusions may provide references to other HTS maglev systems with small levitation gaps, i.e., superconducting magnetic bearings.

  15. On the Motion of the Field of a Permanent Magnet

    Science.gov (United States)

    Leus, Vladimir; Taylor, Stephen

    2011-01-01

    A description is given of a series of recent experiments using a rotating magnetic circuit comprising a permanent magnet ring and yoke, and a stationary conductor in the air gap between the ring and yoke. The EMF induced in this case cannot be described by a simple application of Faraday's flux law. This is because the magnetic flux in the air gap…

  16. Fully permanent magnet atom chip for Bose-Einstein condensation

    NARCIS (Netherlands)

    T. Fernholz; R. Gerritsma; S. Whitlock; I. Barb; R.J.C. Spreeuw

    2008-01-01

    We describe a proof-of-principle experiment on a fully permanent magnet atom chip. We study ultracold atoms and produce a Bose-Einstein condensate. The magnetic trap is loaded efficiently by adiabatic transport of a magnetic trap via the application of uniform external fields. Radio frequency spectr

  17. Magnetic levitation using a stack of high temperature superconducting tape annuli

    Science.gov (United States)

    Patel, A.; Hahn, S.; Voccio, J.; Baskys, A.; Hopkins, S. C.; Glowacki, B. A.

    2017-02-01

    Stacks of large width superconducting tape can carry persistent currents over similar length scales to bulk superconductors, therefore giving them potential for trapped field magnets and magnetic levitation. 46 mm wide high temperature superconducting tape has previously been cut into square annuli to create a 3.5 T persistent mode magnet. The same tape pieces were used here to form a composite bulk hollow cylinder with an inner bore of 26 mm. Magnetic levitation was achieved by field cooling with a pair of rare-earth magnets. This paper reports the axial levitation force properties of the stack of annuli, showing that the same axial forces expected for a uniform bulk cylinder of infinite J c can be generated at 20 K. Levitation forces up to 550 N were measured between the rare-earth magnets and stack. Finite element modelling in COMSOL Multiphysics using the H-formulation was also performed including a full critical state model for induced currents, with temperature and field dependent properties as well as the influence of the ferromagnetic substrate which enhances the force. Spark erosion was used for the first time to machine the stack of tapes proving that large stacks can be easily machined to high geometric tolerance. The stack geometry tested is a possible candidate for a rotary superconducting bearing.

  18. Wide gap, permanent magnet biased magnetic bearing system

    Science.gov (United States)

    Boden, Karl

    1992-01-01

    The unique features and applications of the presented electrical permanent magnetic bearing system essentially result from three facts: (1) the only bearing rotor components are nonlaminated ferromagnetic steel collars or cylinders; (2) all radial and axial forces are transmitted via radial gaps; and (3) large radial bearing gaps can be provided with minimum electric power consumption. The large gaps allow for effective encapsulation and shielding of the rotors at elevated or low temperatures, corrosive or ultra clean atmosphere or vacuum or high pressure environment. Two significant applications are described: (1) a magnetically suspended x ray rotary anode was operated under high vacuum conditions at 100 KV anode potential, 600 C temperature at the rotor collars and speed 18000 rpm with 13 mm radial bearing gap; and (2) an improved Czochralski type crystal growth apparatus using the hot wall method for pulling GaAs single crystals of low dislocation density. Both crystal and crucible are carried and transported by magnetically suspended shafts inside a hermetically sealed housing at 800 C shaft and wall temperature. The radial magnetic bearing gap measures 24 mm.

  19. The influence of low temperature on gamma-ray irradiated permanent magnets.

    Science.gov (United States)

    Han, Young Chul; Cha, Hyun Gil; Kim, Chang Woo; Ji, Eun Sun; Kim, Young Hwan; Kang, Dong In; Kang, Young Soo

    2009-12-01

    The temperature effect on the magnetic property of gamma-ray irradiated Nd-Fe-B and Sr-Ferrite magnets has been investigated. When the permanent magnets are exposed to gamma-ray, it's magnetic and other related properties are declined with degree of dose. The decreased magnetic property by gamma-ray irradiation at low temperature is similar with the result of magnet at high temperature. The temperature effect on the gamma-ray irradiation at exposed moment is also regarded as one of the important parameters for the reduced magnetic properties. The gamma-irradiation at low temperature was carried out at 195 K, and the changed properties of two kinds of magnets before and after gamma-irradiation were comparatively studied. The increased demagnetization of the magnets were studied by Hall probe. And changed Curie temperature and micro-crystal structure of each permanent magnet by gamma-ray irradiation has been also studied. Moreover the strong and broad single line shape of ESR signal in the resonance magnetic field is attributed to unpaired electron of Fe2+ in the sample by the effect of gamma-ray irradiation.

  20. Single Phase Permanent Magnet Low Speed Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Gao Lianxue

    2013-04-01

    Full Text Available In order to acquire a better cognition to the single phase permanent magnet low speed synchronous motor and validate the correctness of the motor mathematical model, the performances of the motor are tested with the single phase permanent magnet low speed synchronous motor whose type is 70TDY4, the corresponding simulations are done too. The resistance and the inductance of the single phase permanent magnet low speed synchronous motor are measured. According to the data of experiments and simulations, the static characteristics of the single phase permanent magnet low speed synchronous motor with the changes of the phase shift resistance and the phase shift capacitance are analysed, the results of experiments and simulations prove the correctness of the mathematics model.

  1. Design of Permanent Magnet Synchronous Generators for Wave Power Generation

    Institute of Scientific and Technical Information of China (English)

    方红伟; 王丹

    2016-01-01

    In this paper, a design method for ocean wave permanent magnet synchronous generator(PMSG)is proposed with new performance criteria to obtain better output performance at the cost of less permanent magnet material. Besides, a simple equivalent analytical geometry method is put forward to calculate the sizes of permanent magnets. Based on geometric and electromagnetic models, four types of rotor structures are compared, i.e., embed-ded, tangential, tile surface mount and convex surface mount structures. The designs and comparisons of machine are performed with the same permanent magnet volume. Moreover, the influences of mechanical pole-arc coeffi-cient of tile surface mount PMSG on electrical efficiency, output power, material corrosion, core loss, and torque ripple are investigated. Finite-element analysis method is applied to verify the results using Ansoft/Maxwell.

  2. Passive control of Permanent Magnet Synchronous Motor chaotic systems

    Institute of Scientific and Technical Information of China (English)

    QI Dong-lian; WANG Jia-jun; ZHAO Guang-zhou

    2005-01-01

    Permanent Magnet Synchronous Motor model can exhibit a variety of chaotic phenomena under some choices of system parameters and external input. Based on the property of passive system, the essential conditions were studied, by which Permanent Magnet Synchronous Motor chaotic system could be equivalent to passive system. Using Lyapunov stability theory, the convergence condition deciding the system's characters was discussed. In the convergence condition area, the equivalent passive system could be globally asymptotically stabilized by smooth state feedback.

  3. Summary on Sensorless permanent magnet Brushless DC Motor Control Strategies

    OpenAIRE

    Li Hai Xia; Cao Yang

    2016-01-01

    This paper aims at discussing the development process and application of permanent magnet brushless DC motor. By referring to the related literatures, this thesis gives an overview of several common non-position sensor detection technologies, analyzing their strengths and weaknesses as well as a number of new and improved methods in practical applications. Besides, The application situation of the electric door with sensorless permanent magnet brushless DC motor was illustrated.

  4. Summary on Sensorless permanent magnet Brushless DC Motor Control Strategies

    Directory of Open Access Journals (Sweden)

    Li Hai Xia

    2016-01-01

    Full Text Available This paper aims at discussing the development process and application of permanent magnet brushless DC motor. By referring to the related literatures, this thesis gives an overview of several common non-position sensor detection technologies, analyzing their strengths and weaknesses as well as a number of new and improved methods in practical applications. Besides, The application situation of the electric door with sensorless permanent magnet brushless DC motor was illustrated.

  5. High-speed, high-temperature magnetic bearings for jet turbine engine application

    Energy Technology Data Exchange (ETDEWEB)

    Mekhiche, M.; Nichols, S.; Hevenhill, D.; Oleksy, J.; Young, J.; Kirtley, J.L. [SatCon Technology Corporation, Cambridge, MA (United States)

    2000-08-01

    In order to double today's jet turbine engines' propulsion capability, lightweight, high-efficiency, high-speed and hightemperature components are sought. These requirements put the conventional components such as the mechanical bearings under excessive constraints and make them obsolete. In this context, SatCon Technology Corporation has developed a high-speed, high- temperature (50 krpm, 600 deg. C) magnetic bearing system that has the potential of meeting the requirements described above. This magnetic bearing system, comprised of two radial and one double acting thrust bearings, was successfully tested to 50,000 rpm. This paper describes the development of this system from its design, through its fabrication and final testing. Details on the system and component requirements are presented, along with a step-by step design and trade-off analysis. Test data and their discussion are provided as well. (orig.)

  6. High temperature magnetic behavior of multiferroics Bi1-xCaxFeO3

    Science.gov (United States)

    Zhang, N.; Su, J.; Liu, Z. Y.; Fu, Z. M.; Wang, X. W.; Song, G. L.; Chang, F. G.

    2014-04-01

    We investigate the room temperature microstructure and high temperature magnetic properties of Ca2+-substituted Bi1-xCaxFeO3 (0 ≤ x ≤ 0.2) ceramics. The Bi1-xCaxFeO3 compound transforms from rhombohedral into tetragonal structure with the phase boundary lying around x = 0.1. Based on this, the magnetic modulation becomes significant and the strongest remnant magnetization Mr is obtained at x = 0.1 compound. An important observation is the ferromagnetic-like phase transition revealed at TFM = 878 K in pure BiFeO3. The TFM of Bi1-xCaxFeO3 varies with Ca concentration and is close to the TAFM when x = 0.1. The convergence between TFM and TAFM implies the severe competition between Fe3+-O2--Fe3+ and unbalanced Fe3+-O2--Fe2+ antiferromagnetic exchange interactions, which leads to the dramatic change around TAFM in the M-T curve of x = 0.1 compound. The structure-related modulation of magnetic structure and complex interaction between Fe3+ and Fe2+ may be the driving force for the excellent magnetic properties of x = 0.1 sample.

  7. Magnetic and magnetocaloric properties of the high-temperature modification of TbTiGe.

    Science.gov (United States)

    Tencé, S; Gaudin, E; Isnard, O; Chevalier, B

    2012-07-25

    The high-temperature form (HT) of the ternary germanide TbTiGe was prepared by melting. The investigation of HT-TbTiGe by x-ray and neutron powder diffractions shows that the compound crystallizes in the tetragonal CeScSi-type structure (space group I4/mmm; a = 404.84(5) and c = 1530.10(9) pm as unit cell parameters). Magnetization and specific heat measurements as well as neutron powder diffraction performed on HT-TbTiGe reveal a ferromagnet having T(C) = 300(1) K as the Curie temperature; the Tb-moments are aligned along the c-axis. This magnetic ordering is associated with a modest magnetocaloric effect around room temperature. The isothermal magnetic entropy change ΔS(m) was determined from the magnetization data; ΔS(m) reaches, respectively, a maximum value of  - 4.3 and  - 2.0 J K(-1) kg(-1) for a magnetic field change of 5 and 2 T.

  8. Interaction between propulsion and levitation system in the HTSC-permanent magnet conveyance system

    Science.gov (United States)

    Ohashi, S.; Nishio, R.; Hashikawa, T.

    2010-11-01

    The magnetically levitated conveyance system has been developed. Pinning force of high temperature bulk superconductors (HTSC) are used for the levitation and the guidance of the carrier. The magnetic rail is set on the ground, and flux from the magnetic rail is pinned by HTSCs on the carrier body. To increase the load weight, the repulsive force of the permanent magnet is introduced. The hybrid levitation system is composed. The repulsive force by the permanent magnet between the load stage on the carrier and the magnetic rail on the ground is used to support the load weight. As the load stage is connected to the carrier body by the linear sliders, the mass of the load weight does not act on the carrier body. The interaction between the electromagnet and the permanent magnet under the load stage generates the propulsion force. The electromagnet is constructed by the air core coils, and excited only when the load stage passes. The interaction between the propulsion and the levitation system is investigated. Disturbance of the propulsion system on the levitation and the guidance force is measured. The results show the influence of the propulsion electromagnet on the pinning force is little, and this propulsion system works effectively.

  9. The Effects of Radiation and Thermal Stability of Sm-Co High Temperature Magnets For High Power Ion Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Since high temperature Sm-Co based magnets were developed, a number of new applications have been introduced. NASA?s Xe+ ion propulsion engine used in Deep Space I...

  10. Study on control method of running velocity for the permanent magnet-HTSC hybrid magnetically levitated conveyance system

    Energy Technology Data Exchange (ETDEWEB)

    Nishio, R.; Ikeda, M.; Sasaki, R. [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan); Ohashi, S., E-mail: ohashi@kansai-u.ac.jp [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2011-11-15

    The hybrid magnetically levitated carrying system is developed. Control method of running velocity of the carrier is studied. Running velocity is controlled by current of the propulsion coils. Propulsion characteristcs are improved. We have developed the magnetically levitated carrying system. In this system, pinning force of high temperature bulk super conductor (HTSC) is used for the levitation and guidance. Four HTSCs are installed on the carrier. The magnetic rail is set on the ground, and flux from the magnetic rail is pinned by HTSCs. To increase levitation force, repulsive force of the permanent magnet is used. The hybrid levitation system is composed. The permanent magnet is installed under the load stage of the carrier. Repulsive force by the permanent magnet between the load stage on the carrier and the magnetic rail on the ground is used to support the load weight. Levitation and guidance one by pinning effect of the YBaCuO HTSC in the carrier is used to levitate the carrier body. The load stage is separated from the carrier flame and can move freely for vertical direction levitation. For the propulsion system, electromagnet is installed on the surface of the magnetic rail. In this paper, control method of running velocity of the carrier is studied. Propulsion force is given as follows; Air core copper coils are installed on the magnetic rail. Interaction between current of these coils and permanent magnets on the carrier generates propulsion force. Running velocity is controlled by current of the propulsion coils. It is also changed by position of the carrier and the load weight. From the results, stability of the propulsion system is given, and propulsion characteristics are improved.

  11. Two cylinder permanent magnet stirrer for liquid metals

    Science.gov (United States)

    Bojarevičs, A.; Baranovskis, R.; Kaldre, I.; Milgrāvis, M.; Beinerts, T.

    2017-07-01

    To achieve a uniform liquid metal composition and temperature distribution, stirring is often necessary for industrial processes. Here, a novel permanent magnet system for liquid melt stirring is proposed. It promises very low energy consumption and options for multiple different flow types compared to traditional travelling magnetic field inductors or mechanical stirrers. The proposed system has a simple design: it consists of two rotating permanent magnet cylinders, which are magnetized transversely to the axis of the cylinders. The experimental device was developed and tested under various regimes using GaInSn alloy in a cylindrical crucible. Aluminum stirring by permanent magnets in laboratory scale is tested, and stirring impact on directional solidification of metallic alloys is experimentally investigated.

  12. High-temperature molecular magnets based on cyanovanadate building blocks: spontaneous magnetization at 230 k.

    Science.gov (United States)

    Entley, W R; Girolami, G S

    1995-04-21

    The molecular-based magnetic materials Cs(2)Mn(||)[V(||)(CN)(6)] (1) and (Et(4)N)(0.5)Mn(l.25)- [V(CN)(5)].2H(2)O (2) (where Et is ethyl) were prepared by the addition of manganese(II) triflate to aqueous solutions of the hexacyanovanadate(II) ion at 0 degrees C. Whereas 1 crystallizes in a face-centered cubic lattice, 2 crystallizes in a noncubic space group. The cesium salt (1) has features characteristic of a three-dimensional ferrimagnet with a Néel transition at 125 kelvin. The tetraethylammonium salt (2) also behaves as a three-dimensional ferrimagnet with a Néel temperature of 230 kelvin; only two other molecular magnets have higher magnetic ordering temperatures. Saturation magnetization measurements indicate that in both compounds the V(II) and high-spin Mn(II) centers are antiferromagnetically coupled. Both 1 and 2 exhibit hysteresis loops characteristic of soft magnets below their magnetic phase-transition temperatures. The high magnetic ordering temperatures of these cyano-bridged solids confirm that the incorporation of early transition elements into the lattice promotes stronger magnetic coupling by enhancing the backbonding into the cyanide pi* orbitals.

  13. Growth anisotropy effect of bulk high temperature superconductors on the levitation performance in the applied magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, J., E-mail: jzheng@swjtu.edu.cn; Liao, X.L.; Jing, H.L.; Deng, Z.G.; Yen, F.; Wang, S.Y.; Wang, J.S.

    2013-10-15

    Highlights: • The single-layer bulk HTSC with AGSBP obtains better levitation performance than that of MGSBP. • The double-layer bulk with AGSBP obtains better levitation performance than that of MGSBP too. • The double-layer bulk finding is contrast to MGSBP if pursuing high trapped field. • The optimization is highlighted by simple and easy operation, thus economical in the practice. -- Abstract: Growth anisotropies of bulk high temperature superconductors (HTSCs) fabricated by a top-seeded melt texture growth process, that is, different pinning effect in the growth sectors (GSs) and growth sector boundaries (GSBs), possess effect on the macro flux trapping and levitation performance of bulk HTSCs. Previous work (Physics Procedia, 36 (2012) 1043) has found that the bulk HTSC array with aligned GSB pattern (AGSBP) exhibits better capability for levitation and suppression of levitation force decay above a permanent magnet guideway (PMG) compared with misaligned GSB pattern (MGSBP). In this paper, we further examine this growth anisotropy effect on the maglev performance of a double-layer bulk HTSC. In contrast to reported trapped flux cases (Supercond. Sci. Technol. 19 (2006) S466), the two superposed bulk HTSCs with same AGSBP with PMG are found to show better maglev performance. These series of results are helpful and support a new way for the performance optimization of present HTS maglev systems.

  14. Contribution to permanent magnet excited dc linear actuators

    Energy Technology Data Exchange (ETDEWEB)

    Okonkwo, R.C.; Hanitsch, R. [Technische Univ. Berlin (Germany)

    1998-07-01

    In this paper an efficient method for the computation of magnetic fields and forces in dc linear actuators built with Sm{sub 2}Co{sub 17} - permanent magnet is presented. The results obtained show good agreement with measurements. (orig.)

  15. Variable-period permanent-magnet helical undulator

    OpenAIRE

    Jungho Mun; Young Uk Jeong; Vinokurov, Nikolay A.; Kitae Lee; Kyu-Ha Jang; Seong Hee Park; Min Yong Jeon; Sang-In Shin

    2014-01-01

    We realized a variable-period permanent-magnet helical undulator with high (∼1  T) field amplitude, which is almost constant over undulator periods of 23–26 mm. Each undulator period has four modular sections of iron poles and permanent magnets embedded in nonmagnetic disks with holes along the undulator axis. Modular plates undergo a longitudinal repulsive force from the magnetic field pressure and the spring coils between modular plates. The undulator period can thus be controlled by mechan...

  16. Use of a High-Temperature Superconducting Coil for Magnetic Energy Storage

    Science.gov (United States)

    Fagnard, J.-F.; Crate, D.; Jamoye, J.-F.; Laurent, Ph; Mattivi, B.; Cloots, R.; Ausloos, M.; Genon, A.; Vanderbemden, Ph

    2006-06-01

    A high temperature superconducting magnetic energy storage device (SMES) has been realised using a 350 m-long BSCCO tape wound as a ''pancake'' coil. The coil is mounted on a cryocooler allowing temperatures down to 17.2 K to be achieved. The temperature dependence of coil electrical resistance R(T) shows a superconducting transition at T = 102.5 K. Measurements of the V(I) characteristics were performed at several temperatures between 17.2 K and 101.5 K to obtain the temperature dependence of the critical current (using a 1 µV/cm criterion). Critical currents were found to exceed 100 A for T power supply as bridge input voltage. The coil current, the bridge input and output voltages were recorded simultaneously. Using a 10 A setpoint current in the superconducting coil, the whole system (coil + DC-DC converter) can provide a stable output voltage showing uninterruptible power supply (UPS) capabilities over 1 s.

  17. Superconducting flux pump for high-temperature superconductor insert coils of NMR magnets

    Science.gov (United States)

    Jeong, S.; Lee, H.; Iwasa, Y.

    2002-05-01

    This paper describes a prototype flux pump recently operated at the MIT Francis Bitter Magnet Laboratory. The results of the prototype flux pump will be used in the development of a full-scale flux pump that will be coupled to a high-temperature superconductor (HTS) insert coil of a high-field NMR magnet. Such an HTS insert is unlikely to operate in persistent mode because of the conductor's low index (n). The flux pump can compensate for field decay in the HTS insert coil and make the insert operate effectively in persistent mode. The flux pump, comprised essentially of a transformer and two switches, all made of superconductor, transfers into the insert coil a fraction of a magnetic energy that is first introduced in the secondary circuit of the transformer by a current supplied to the primary circuit. A prototype flux pump has been designed, fabricated, and operated to demonstrate that a flux pump can indeed supply a small metered current into a load superconducting magnet. A current increment in the range of microamperes has been measured in the magnet after each pumping action. The superconducting prototype flux pump is made of Nb3Sn tape. The pump is placed in a gaseous environment above the liquid helium level to keep its heat dissipation from directly discharged in the liquid; the effluent helium vapor maintains the thermal stability of the flux pump. [This paper is also published in Advances in Cryogenic Engineering Volume 47A, AIP Conference Proceedings Volume 613, pp. 441-448.

  18. Bonded permanent magnets: Current status and future opportunities (invited)

    Science.gov (United States)

    Ormerod, John; Constantinides, Steve

    1997-04-01

    Permanent magnets play a vital role in modern society as a component in a wide range of devices utilized by many industries and consumers. In 1995, the world production of permanent magnets was estimated to be valued at 3.6 billion and growing at an annual rate of 12%. Bonded permanent magnets are the fastest growing segment of this market. Bonded magnet technology enables a wide variety of magnetic powders to be combined with several polymer and binder systems to produce magnetic components utilizing several processing options. In this article, we review the development of bonded magnet technology. The major classes of magnetic powders, binder systems, and processing technologies are described. Recent developments in magnetic material grades, e.g., anisotropic NdFeB, rare earth lean NdFeB, SmFe(N,C) are outlined. The current status of processing and binder options aimed at increasing the upper application temperature limit of these materials is highlighted. Finally, the improvements and future opportunities for bonded magnets are discussed.

  19. System Cost Analysis for an Interior Permanent Magnet Motor

    Energy Technology Data Exchange (ETDEWEB)

    Peter Campbell

    2008-08-01

    The objective of this program is to provide an assessment of the cost structure for an interior permanent magnet ('IPM') motor which is designed to meet the 2010 FreedomCAR specification. The program is to evaluate the range of viable permanent magnet materials for an IPM motor, including sintered and bonded grades of rare earth magnets. The study considers the benefits of key processing steps, alternative magnet shapes and their assembly methods into the rotor (including magnetization), and any mechanical stress or temperature limits. The motor's costs are estimated for an annual production quantity of 200,000 units, and are broken out into such major components as magnetic raw materials, processing and manufacturing. But this is essentially a feasibility study of the motor's electromagnetic design, and is not intended to include mechanical or thermal studies as would be done to work up a selected design for production.

  20. Electric-field assisted switching of magnetization in perpendicularly magnetized (Ga,Mn)As films at high temperatures

    Science.gov (United States)

    Wang, Hailong; Ma, Jialin; Yu, Xueze; Yu, Zhifeng; Zhao, Jianhua

    2017-01-01

    The electric-field effects on the magnetism in perpendicularly magnetized (Ga,Mn)As films at high temperatures have been investigated. An electric-field as high as 0.6 V nm-1 is applied by utilizing a solid-state dielectric Al2O3 film as a gate insulator. The coercive field, saturation magnetization and magnetic anisotropy have been clearly changed by the gate electric-field, which are detected via the anomalous Hall effect. In terms of the Curie temperature, a variation of about 3 K is observed as determined by the temperature derivative of the sheet resistance. In addition, electrical switching of the magnetization assisted by a fixed external magnetic field at 120 K is demonstrated, employing the gate-controlled coercive field. The above experimental results have been attributed to the gate voltage modulation of the hole density in (Ga,Mn)As films, since the ferromagnetism in (Ga,Mn)As is carrier-mediated. The limited modulation magnitude of magnetism is found to result from the strong charge screening effect introduced by the high hole concentration up to 1.10  ×  1021 cm-3, while the variation of the hole density is only about 1.16  ×  1020 cm-3.

  1. Lunar magnetic field - Permanent and induced dipole moments

    Science.gov (United States)

    Russell, C. T.; Coleman, P. J., Jr.; Schubert, G.

    1974-01-01

    Apollo 15 subsatellite magnetic field observations have been used to measure both the permanent and the induced lunar dipole moments. Although only an upper limit of 1.3 x 10 to the 18th gauss-cubic centimeters has been determined for the permanent dipole moment in the orbital plane, there is a significant induced dipole moment which opposes the applied field, indicating the existence of a weak lunar ionosphere.

  2. Design and characterization of permanent magnetic solenoids for REGAE

    Energy Technology Data Exchange (ETDEWEB)

    Hachmann, M., E-mail: max.hachmann@desy.de [Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg (Germany); Flöttmann, K. [Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg (Germany); Gehrke, T. [Deutsches Krebsforschungszentrum DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Mayet, F. [Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg (Germany)

    2016-09-01

    REGAE is a small electron linear accelerator at DESY. In order to focus short and low charged electron bunches down to a few μm permanent magnetic solenoids were designed, assembled and field measurements were done. Due to a shortage of space close to the operation area an in-vacuum solution has been chosen. Furthermore a two-ring design made of wedges has been preferred in terms of beam dynamic issues. To keep the field quality of a piecewise built magnet still high a sorting algorithm for the wedge arrangement including a simple magnetic field model has been developed and used for the construction of the magnets. The magnetic field of these solenoids has been measured with high precision and compared to simulations. - Highlights: • presenting a two-ring radially magnetized permanent magnetic solenoid design. • development of a analytical field description and field quality factor. • development of a sorting algorithm for permanent magnetic pieces to form a magnet. • performing a high-precision field measurement of a high gradient field.

  3. Design, manufacture and measurements of permanent dipole magnets for DIRAC

    CERN Document Server

    Vorozhtsov, A; Kasaei, S; Solodko, E; Thonet, P A; Tommasini, D

    2013-01-01

    The one of the aim of the DIRAC experiment is the observation of the long-lived π+π- atoms, using the proton beam of the CERN Proton Synchrotron [1]. Two dipole magnets are needed for the for the DIRAC experiment as high resolution spectrometers. The dipole magnet will be used to identify the long-lived atoms on the high level background of π+π- pairs produced simultaneously with π+π- atoms. The proposed design is a permanent magnet dipole with a mechanical aperture of 60 mm. The magnet, of a total physical length of 66 mm, is based on Sm2Co17 blocks and provides an integrated field strength of 24·10-3 T×m. The Sm2Co17 was chosen as a material for the permanent magnet blocks due to its radiation hardness and weaker temperature dependence. The magnetic field quality is determined by 2 ferromagnetic poles, aligned together with the permanent magnets blocks. The paper describes the design, manufacture and magnetic measurements of the magnets.

  4. Soldered joints—an essential component of demountable high temperature superconducting fusion magnets

    Science.gov (United States)

    Tsui, Yeekin; Surrey, Elizabeth; Hampshire, Damian

    2016-07-01

    Demountable superconducting magnet coils would offer significant benefits to commercial nuclear fusion power plants. Whether large pressed joints or large soldered joints provide the solution for demountable fusion magnets, a critical component or building block for both will be the many, smaller-scale joints that enable the supercurrent to leave the superconducting layer, cross the superconducting tape and pass into the solder that lies between the tape and the conductor that eventually provides one of the demountable surfaces. This paper considers the electrical and thermal properties of this essential component part of demountable high temperature superconducting (HTS) joints by considering the fabrication and properties of jointed HTSs consisting of a thin layer of solder (In52Sn48 or Pb38Sn62) sandwiched between two rare-earth-Ba2Cu3O7 (REBCO) second generation HTS coated conductors (CCs). The HTS joints are analysed using numerical modelling, critical current and resistivity measurements on the joints from 300 to 4.2 K in applied magnetic fields up to 12 T, as well as scanning electron microscopy studies. Our results show that the copper/silver layers significantly reduce the heating in the joints to less than a few hundred mK. When the REBCO alone is superconducting, the joint resistivity (R J) predominantly has two sources, the solder layer and an interfacial resistivity at the REBCO/silver interface (∼25 nΩ cm2) in the as-supplied CCs which together have a very weak magnetoresistance in fields up to 12 T. We achieved excellent reproducibility in the R J of the In52Sn48 soldered joints of better than 10% at temperatures below T c of the REBCO layer which can be compared to variations of more than two orders of magnitude in the literature. We also show that demountable joints in fusion energy magnets are viable and need only add a few percent to the total cryogenic cost for a fusion tokamak.

  5. Special-Purpose High-Torque Permanent-Magnet Motors

    Science.gov (United States)

    Doane, George B., III

    1995-01-01

    Permanent-magnet brushless motors that must provide high commanded torques and satisfy unusual heat-removal requirement are developed. Intended for use as thrust-vector-control actuators in large rocket engines. Techniques and concepts used to design improved motors for special terrestrial applications. Conceptual motor design calls for use of rotor containing latest high-energy-product rare-earth permanent magnets so that motor produces required torque while drawing smallest possible currents from power supply. Torque generated by electromagnetic interaction between stator and permanent magnets in rotor when associated electronic circuits applied appropriately temporally and spatially phased currents to stator windings. Phase relationships needed to produce commanded torque computed in response to torque command and to electronically sensed angular position of rotor relative to stator.

  6. Dynamic Analysis of Permanent Magnet Synchronous Generator with Power Electronics

    Directory of Open Access Journals (Sweden)

    OZCIRA, S.

    2010-05-01

    Full Text Available Permanent magnet DC motor-generators (PMDC, PMSG have been widely used in industrial and energy sectors recently. Power control of these systems can be achieved by controlling the output voltage. In this study, PMDC-PMSG systems are mathematically modeled and simulated in MATLAB and Simulink software. Then the results are discussed. A low power permanent magnet synchronous generator is driven by a permanent magnet DC motor and the output voltage is controlled by a frequency cycle-converter. The output of a half-wave uncontrolled rectifier is applied to an SPWM inverter and the power is supplied to a 300V, 50Hz load. The load which is connected to an LC filter is modeled by state-space equations. LC filter is utilized in order to suppress the voltage oscillations at the inverter output.

  7. Asynchronous slip-ring motor synchronized with permanent magnets

    Directory of Open Access Journals (Sweden)

    Glinka Tadeusz

    2017-03-01

    Full Text Available The electric LSPMSM motor presented in the paper differs from standard induction motor by rotor design. The insulated start-up winding is located in slots along the rotor circumference. The winding ends are connected to the slip-rings. The rotor core contains permanent magnets. The electromechanical characteristics for synchronous operation were calculated, as were the start-up characteristics for operation with a short-circuited rotor winding. Two model motors were used for the calculations, the V-shaped Permanent Magnet (VPM – Fig. 3, and the Linear Permanent Magnet (IPM – Fig. 4, both rated at 14.5 kW. The advantages of the investigated motor are demonstrated in the conclusions.

  8. Proposal of Permanent Magnet Repulsive Maglev Transportation System

    Science.gov (United States)

    Moriyama, Shin-Ichi

    This paper describes a maglev transportation system for automobile. The track is an array of permanent magnet blocks, and the levitating body is the bedplate which consists of permanent magnet plates, propulsion coils, levitation coils and guidance coils. The feature of this system is that the automobile equipped with the bedplate is free to approach into the track or to swerve from the track by using four wheels with the lift. The force acting on the levitating body is calculated on the assumption that each permanent magnet can be expressed as a surface current. From the calculation results, it is proven that the automobile of 4.35m length, 1.8m width and 1700kg weight can run at speed of 500km/h against the air resistance force of 3704N on the condition that the battery has an output of 337.5V and a capacity of 190Ah.

  9. High-temperature annealing effects on multiwalled carbon nanotubes: electronic structure, field emission and magnetic behaviors.

    Science.gov (United States)

    Ray, Sekhar Chandra; Pao, Chih-Wen; Tsai, Huang-Ming; Chen, Huang-Chin; Chen, Yu-Shin; Wu, Shang-Lun; Ling, Dah-Chin; Lin, I-Nan; Pong, Way-Faung; Gupta, Sanju; Giorcelli, Mauro; Bianco, Stefano; Musso, Simone; Tagliaferro, Alberto

    2009-12-01

    This work elucidates the effects of high-temperature annealing on the microscopic and electronic structure of multiwalled carbon nanotubes (MWCNTs) using high-resolution transmission electron microscopy, micro-Raman spectroscopy, X-ray diffraction, X-ray absorption near-edge structure (XANES) and valence-band photoemission spectroscopy (VBPES), respectively. The field emission and magnetization behaviors are also presented. The results of annealing are as follows: (1) MWCNTs tend to align in the form of small fringes along their length, promote graphitization and be stable in air, (2) XANES indicates an enhancement in oxygen content on the sample, implying that it can be adopted for sensing and storing oxygen gas, (3) the electron field emission current density (J) is enhanced and the turn-on electric field (E(TOE)) reduced, suggesting potential use in field emission displays and as electron sources in microwave tube amplifiers and (4) as-grown MWCNTs with embedded iron nanoparticles exhibits significantly higher coercivity approximately 750 Oe than its bulk counterpart (Fe(bulk) approximately 0.9 Oe), suggesting its potential use as low-dimensional high-density magnetic recording media.

  10. Magneto-thermal phenomena in bulk high temperature superconductors subjected to applied AC magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Vanderbemden, P; Laurent, P [SUPRATECS and Department of Electrical Engineering and Computer Science B28, Sart-Tilman, B-4000 Liege (Belgium); Fagnard, J-F [SUPRATECS, Royal Military Academy of Belgium, Avenue de la Renaissance, B-1000 Brussels (Belgium); Ausloos, M [SUPRATECS and Department of Physics B5, Sart-Tilman, B-4000 Liege (Belgium); Hari Babu, N [Brunel Centre for Advanced Solidification Technology (BCAST), Brunel University, West London UB8 3PH (United Kingdom); Cardwell, D A, E-mail: Philippe.Vanderbemden@ulg.ac.b [Bulk Superconductivity Group, Engineering Department, University of Cambridge, Cambridge CB2 1PZ (United Kingdom)

    2010-07-15

    In the present work we study, both theoretically and experimentally, the temperature increase in a bulk high temperature superconductor subjected to applied AC magnetic fields of large amplitude. We calculate analytically the equilibrium temperatures of the bulk sample as a function of the experimental parameters using a simple critical state model for an infinitely long type-II superconducting slab or cylinder. The results show the existence of a limit heat transfer coefficient (AU{sub lim}) separating two thermal regimes with different characteristics. The theoretical analysis predicts a 'forbidden' temperature window within which the temperature of the superconductor can never stabilize when the heat transfer coefficient is small. In addition, we determine analytical expressions for two threshold fields H{sub tr1} and H{sub tr2} characterizing the importance of magneto-thermal effects and show that a thermal runaway always occurs when the field amplitude is larger than H{sub tr2}. The theoretical predictions of the temperature evolution of the bulk sample during a self-heating process agree well with the experimental data. The simple analytical study presented in this paper enables order of magnitude thermal effects to be estimated for simple superconductor geometries under applied AC magnetic fields and can be used to predict the influence of experimental parameters on the self-heating characteristics of bulk type-II superconductors.

  11. M-H characteristics and demagnetization resistance of samarium-cobalt permanent magnets to 300 C

    Science.gov (United States)

    Niedra, Janis M.

    1992-01-01

    The influence of temperature on the M-H demagnetization characteristics of permanent magnets is important information for the full utilization of the capabilities of samarium-cobalt magnets at high temperatures in demagnetization-resistant permanent magnet devices. In high temperature space power converters, such as free-piston Stirling engine driven linear alternators, magnet demagnetization can occur as a long-term consequence of thermal agitation of domains and of metallurgical change, and also as an immediate consequence of too large an applied field. Investigated here is the short-term demagnetization resistance to applied fields derived from basic M-H data. This quasistatic demagnetization data was obtained for commercial, high-intrinsic-coercivity, Sm2Co17-type magnets from 5 sources, in the temperature range 23 to 300 C. An electromagnet driven, electronic hysteresigraph was used to test the 1-cm cubic samples. The observed variation of the 2nd quadrant M-H characteristics was a typical rapid loss of M-coercivity and a relatively lesser loss of remanence with increasing temperature. The 2nd quadrant M-H curve knee point is used to define the limits of operation safe against irreversible demagnetization due to an excessive bucking field for a given flux density swing at temperature. Such safe operating area plots are shown to differentiate the high temperature capabilities of the samples from different sources. For most of the samples, their 2nd quadrant M-H loop squareness increased with temperature, reaching a peak or a plateau above 250 C.

  12. Build Axial Gradient Field by Using Axial Magnetized Permanent Rings

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Axial magnetic field produced by an axial magnetized permanent ring was studied. For two permanent rings, if they are magnetized in the same directions, a nearly uniform axial field can be produced. If they are magnetized in opposite direction,an axial gradient magnetic field can be generated, with the field range changing from -B0 to B0. A permanent magnet with a high axial gradient field was fabricated, the measured results agree with the PANDIRA calculation very well. For wider usage,it is desirable for the field gradient to be changed. Some methods to produce the variable gradient field are presented. These kinds of axial gradient magnetic field can also be used as a beam focusing for linear accelerator if the periodic field can be produced along the beam trajectory. The axial magnetic field is something like a solenoid, large stray field will leak to the outside environment if no method is taken to control them. In this paper, one method is illustrated to shield off the outside leakage field.

  13. Magnetic field asymmetry and high temperature magnetoresistance in single-walled carbon nanotubes

    Science.gov (United States)

    Cobden, David

    2006-03-01

    The length scales and scattering processes in the one-dimensional electron system in single-walled carbon nanotubes remain only partially understood. Measuring the magnetoresistance, in both linear and nonlinear response, is a way to investigate these processes. In disordered nanotubes with ballistic paths much shorter than the length, we observe magnetoresistance in the metallic regime which at low temperatures resembles the universal fluctuations and weak localization seen in higher dimensional metals. A parabolic magnetoresistance persists at room temperature, indicating a significant role for phase coherence and/or interactions at high temperatures. While the linear resistance of a two-terminal sample must be an even function of magnetic field B by Onsager's principle, the nonlinear resistance need not be. Importantly, the B-asymmetric nonlinear terms can in principle be used to infer the strength of electron-electron interactions in the sample [1]. We have therefore also measured in detail the lowest order B-asymmetric current contributions, with a focus on the B-linear term. This has apparently not been done before in any system. Consistent with general theory, at high temperatures the term is small and has a constant sign independent of Fermi energy. At low temperatures it grows and develops mesoscopic fluctuations. Although these result imply that interactions are involved in the transport, calculations specific to nanotubes are needed in order to extract interaction parameters. This work was done by the authors of Ref [2]. References: [1] E.L. Ivchenko and B. Spivak, Phys. Rev. B 66, 155404 (2002); [2] Jiang Wei, Michael Shimogawa, Zenghui Wang, Iuliana Radu, Robert Dormaier, and David H. Cobden, Phys. Rev. Lett. (Dec. 2005) (cond-mat/0506275).

  14. Miniature high speed compressor having embedded permanent magnet motor

    Science.gov (United States)

    Zhou, Lei (Inventor); Zheng, Liping (Inventor); Chow, Louis (Inventor); Kapat, Jayanta S. (Inventor); Wu, Thomas X. (Inventor); Kota, Krishna M. (Inventor); Li, Xiaoyi (Inventor); Acharya, Dipjyoti (Inventor)

    2011-01-01

    A high speed centrifugal compressor for compressing fluids includes a permanent magnet synchronous motor (PMSM) having a hollow shaft, the being supported on its ends by ball bearing supports. A permanent magnet core is embedded inside the shaft. A stator with a winding is located radially outward of the shaft. The PMSM includes a rotor including at least one impeller secured to the shaft or integrated with the shaft as a single piece. The rotor is a high rigidity rotor providing a bending mode speed of at least 100,000 RPM which advantageously permits implementation of relatively low-cost ball bearing supports.

  15. Analysis and Design of Hybrid Excitation Permanent Magnet Synchronous Generators

    Institute of Scientific and Technical Information of China (English)

    JIN Wan-bing; ZHANG Dong; AN Zhong-liang; TAN Ren-yuan

    2006-01-01

    On the basis of a conventional permanent magnet (PM) synchronous generator's construction,a novel kind of Hybrid Excitation Permanent Magnet Synchronous Generator (HEPMSG) is introduced by inserting exciting winding in the stator or rotor.Firstly,the construction of HEPMSG is improved with the addition of PM excitation on the ferromagnetic pole,and its working principle and design method are studied in detail.Then,an appropriate exciting current control system is presented considering the characteristics of HEPMSG.Finally,a prototype is made,and test results confirm the analysis and design.

  16. Motor Integrated Permanent Magnet Gear in a Battery Electrical Vehicle

    DEFF Research Database (Denmark)

    Frandsen, Tommy; Mathe, Laszlo; Berg, Nick Ilsø

    2015-01-01

    This paper presents the physical construction and test results of two new demonstrators of a Motor Integrated Permanent Magnet Gear (MIPMG), which is a second version of an already tested demonstrator. The demonstrators will be used as traction units for a Battery Electrical Vehicle (BEV) and the......This paper presents the physical construction and test results of two new demonstrators of a Motor Integrated Permanent Magnet Gear (MIPMG), which is a second version of an already tested demonstrator. The demonstrators will be used as traction units for a Battery Electrical Vehicle (BEV...

  17. Magnetic, structural, and transport properties at very high temperature in manganites

    Energy Technology Data Exchange (ETDEWEB)

    Nima Ramirez, Fabian Enrique; Furlan Ferreira, Fabio; Andrade Alves, Wendel; Queiruga Rey, Jose Fernando [Centro de Ciencias Naturais e Humanas, Universidade Federal do ABC, Santo Andre, CEP 09090-400, SP (Brazil); Souza, Jose Antonio, E-mail: joseantonio.souza@ufabc.edu.br [Centro de Ciencias Naturais e Humanas, Universidade Federal do ABC, Santo Andre, CEP 09090-400, SP (Brazil)

    2012-07-15

    Magnetic, structural, and electric transport measurements at high temperatures were carried out on La{sub 1-x}Ca{sub x}MnO{sub 3}; x=0.20, 0.25, 0.30, 0.34, 0.40, and 0.45. All samples show a first-order structural phase transition from orthorhombic Pnma to rhombohedral R3{sup Macron }c space group at T{sub R-O}. Magnetic susceptibility measurements show that the Curie-Weiss law is strictly obeyed in the rhombohedral phase as opposed to the orthorhombic phase where the effective magnetic moment has a temperature dependence. The electrical resistivity is well described by the small polaron hopping mechanism in the samples up to x=0.34. As the charge carriers are introduced into the system (x=0.40 and 0.45), this mechanism of hopping ceases to be valid. The value of Grueneisen parameter obtained through analysis of high-resolution X-ray powder diffraction as a function of temperature increases abruptly for the sample with x=0.40. This is consistent with an increase in bending and stretchinglike frequency modes observed by Raman spectroscopy. - Highlights: Black-Right-Pointing-Pointer Curie-Weiss law is strictly obeyed in the R3c phase as opposed in the Pnma one. Black-Right-Pointing-Pointer The small polaron hopping ceases to be valid as charge carriers increases. Black-Right-Pointing-Pointer The Gruneisen parameter obtained through HR X-ray diffraction increases abruptly.

  18. Design and Analysis of Tubular Permanent Magnet Linear Wave Generator

    Directory of Open Access Journals (Sweden)

    Jikai Si

    2014-01-01

    Full Text Available Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG.

  19. Design and analysis of tubular permanent magnet linear wave generator.

    Science.gov (United States)

    Si, Jikai; Feng, Haichao; Su, Peng; Zhang, Lufeng

    2014-01-01

    Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG) and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG.

  20. Some Character of Application of Nd-Fe-B Permanent Magnet

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The character of application of Nd-Fe-B permanent magnet is characterized in an irreversible loss of magnetic flux in the various environment conditions. According to the size of permanent magnet in the various environment conditions the irreversible loss of the permanent magnets is very different. Therefore, the irreversible loss and the application method according to the size of permanent magnets and the intervals in the magnetic system are discussed.

  1. A modified Rogowski coil for measurements of hybrid permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Bertsche, K.

    1996-08-01

    For large permanent magnets, as proposed for the Fermilab Recycler Ring, it may be important to quickly verify that the magnet`s strength is correct. This may be important, for example, if a magnet is suspected of having changed due to some sort of accident. The field strength of a pure dipole can be readily measured with a Hall probe, but for indexed dipoles and for quadrupoles a Hall probe will not give very accurate results without precise positioning. We have investigated a different approach, the use of a modified Rogowski coil to measure the magnetic potential of each pole. As long as magnet geometry is fixed and known, measurement of the magnetic potential at each pole gives a good measurement of field strength even for magnets with large quadrupole components. The construction and use of such a coil and the precision of measurements made with it will be discussed. 4 refs., 5 figs.

  2. CALCULATION OF INDUCTANCE OF THE INTERIOR PERMANENT MAGNET SYNCHRONOUS MOTOR

    Directory of Open Access Journals (Sweden)

    Phyong Le Ngo

    2017-01-01

    Full Text Available Interior permanent magnet synchronous motor (IPMSM refers to salient-pole synchronous motors, characterized by inequality of inductances of longitudinal (d and transverse (q axes. Electromagnetic torque of IPMSM consists of two components: active torque and reactive torque; the latter depends on inductances of d and q axes. An analytical method to calculate own inductances and mutual inductances of a three-phase IPMSM is presented. Distributed windings of the stator are substituted by equivalent sine distributed windings. An interior permanent magnets rotor is substituted by an equivalent salient-pole rotor. Sections of a magnetic circuit comprising interior permanent magnets, air barriers and steel bridges are substituted by equivalent air-gap. The expressions of the magnetic induction created by current of the stator windings at each point of the air gap as well as of magnetic flux linkage of the stator windings have been obtained. The equations of the self-inductances of phases A, B, C, and of inductance of mutual induction are determined from magnetic flux linkage. The inductance of the d and q axes have been obtained as a result of transformation of the axes abc–dq. The results obtained with the use of the proposed analytical method and the finite element method are presented in the form of a graph; the calculations that have been obtained by these two methods were compared. 

  3. Performance characterization of a permanent-magnet helicon plasma thruster

    Science.gov (United States)

    Takahashi, Kazunori; Charles, Christine; Boswell, Rod

    2012-10-01

    Helicon plasma thrusters operated at a few kWs of rf power is an active area of an international research. Recent experiments have clarified part of the thrust-generation mechanisms. Thrust components which have been identified include an electron pressure inside the source region and a Lorentz force due to an electron diamagnetic drift current and a radial component of the applied magnetic field. The use of permanent magnets (PMs) instead of solenoids is one of the solutions for improving the thruster efficiency because it does not require electricity for the magnetic nozzle formation. Here the thrust imparted from a permanent-magnet helicon plasma thruster is directly measured using a pendulum thrust balance. The source consists of permanent magnet (PM) arrays, a double turn rf loop antenna powered by a 13.56 MHz rf generator and a glass source tube. The PM arrays provide a magnetic nozzle near the open exit of the source and two configurations, which have maximum field strengths of about 100 and 270 G, are tested. A thrust of 15 mN, specific impulse of 2000 sec and a thrust efficiency of 8 percent are presently obtained for 2 kW of input power, 24 sccm flow rate of argon and the stronger magnetic field configuration.

  4. Modeling of Hybrid Permanent Magnetic-Gas Bearings

    DEFF Research Database (Denmark)

    Morosi, Stefano; Santos, Ilmar

    2009-01-01

    Modern turbomachinery applications require nowadays ever-growing rotational speeds and high degree of reliability. It then becomes natural to focus the attention of the research to contact-free bearings elements. The present alternatives focus on gas lubricated journal bearings or magnetic bearings....... In the present paper both the technologies are combined with the aim of developing a new kind of hybrid permanent magnetic - gas bearing. This new kind of machine is intended to exploit the benefits of the two technologies while minimizing their drawbacks. The poor start-up and low speed operation performance...... of the gas bearing is balanced by the properties of the passive magnetic one. At high speeds the dynamic characteristics of the gas bearing are improved by offsetting the stator ring of the permanent magnetic bearing. Furthermore this design shows a kind of redundancy, which offers soft failure properties...

  5. Optimal Design Solutions for Permanent Magnet Synchronous Machines

    Directory of Open Access Journals (Sweden)

    POPESCU, M.

    2011-11-01

    Full Text Available This paper presents optimal design solutions for reducing the cogging torque of permanent magnets synchronous machines. A first solution proposed in the paper consists in using closed stator slots that determines a nearly isotropic magnetic structure of the stator core, reducing the mutual attraction between permanent magnets and the slotted armature. To avoid complications in the windings manufacture technology the stator slots are closed using wedges made of soft magnetic composite materials. The second solution consists in properly choosing the combination of pole number and stator slots number that typically leads to a winding with fractional number of slots/pole/phase. The proposed measures for cogging torque reduction are analyzed by means of 2D/3D finite element models developed using the professional Flux software package. Numerical results are discussed and compared with experimental ones obtained by testing a PMSM prototype.

  6. Rational design of the exchange-spring permanent magnet.

    Science.gov (United States)

    Jiang, J S; Bader, S D

    2014-02-12

    The development of the optimal exchange-spring permanent magnet balances exchange hardening, magnetization enhancement, and the feasibility of scalable fabrication. These requirements can be met with a rational design of the microstructural characteristics. The magnetization processes in several model exchange-spring structures with different geometries have been analyzed with both micromagnetic simulations and nucleation theory. The multilayer geometry and the soft-cylinders-in-hard-matrix geometry have the highest achievable figure of merit (BH)max, while the soft-spheres-in-hard-matrix geometry has the lowest upper limit for (BH)max. The cylindrical geometry permits the soft phase to be larger and does not require strict size control. Exchange-spring permanent magnets based on the cylindrical geometry may be amenable to scaled-up fabrication.

  7. The permanent and induced magnetic dipole moment of the moon

    Science.gov (United States)

    Russell, C. T.; Coleman, P. J., Jr.; Lichtenstein, B. R.; Schubert, G.

    1974-01-01

    Magnetic field observations with the Apollo 15 subsatellite have been used to deduce the components of both the permanent and induced lunar dipole moments in the orbital plane. The present permanent lunar magnetic dipole moment in the orbital plane is less than 1.3 times ten to the eighteenth power gauss-cu cm. Any uniformly magnetized near surface layer is therefore constrained to have a thickness-magnetization product less than 2.5 emu-cm per g. The induced moment opposes the external field, implying the existence of a substantial lunar ionosphere with a permeability between 0.63 and 0.85. Combining this with recent measures of the ratio of the relative field strength at the ALSEP and Explorer 35 magnetometers indicates that the global lunar permeability relative to the plasma in the geomagnetic tail lobes is between 1.008 and 1.03.

  8. Investigation Procedure of Magnetic Performances of NdFeB Permanent Magnets

    DEFF Research Database (Denmark)

    Calin, Marius-Daniel; Helerea, Elena; Ritchie, Ewen

    2011-01-01

    The permanent magnet applications based on carbon steel magnets, hard ferrites and AlNiCo magnets classes are renewed with new classes of advanced magnetic materials based on rare earth elements, the Sm-Co and NdFeB types. Performance increase of the hard magnetic materials and their use...... in specific applications impose also great advances in the field of magnetic measurement. New researches need to be validated in order to investigate the NdFeB permanent magnets performances, including their stability under different thermal operational regimes. In this paper a specific investigation...... procedure of magnetic performances of NdFeB permanent magnets in correlation with the range of operating temperature is proposed based on modern hysteresisgraph method and impulse magnetization technique....

  9. Preferred Orientation in Nanocomposite Permanent Magnet Materials

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Melt-spun (Nd11.4Fe82.9B5.7)0.99M1 ribbons (M=Zr, Nb, Ga, Zr+Ga, Nb+Ga) were prepared by melt-spinning technique. Ga addition is found to be effective for the orientation of c-axis of Nd2Fe14B grains perpendicular to the ribbon plane. Better magnetic properties can be achieved by adding both the two kinds of elements Zr+Ga, Nb+Ga, and it is found that the preferred orientation is further improved. The alignment degree changes with ribbon thickness and is highest when ribbon thickness is 120 μm. Heat treatment can improve the texture degree, but lead to coarser grains. Cryogenic treatment is first applied for the treatment of nanocomposite Nd2Fe14B/α-Fe melt-spun ribbons. The effects on magnetic properties and texture degree of nanocomposite magnets after cryogenic treatment were studied. The result shows that cryogenic treatment is beneficial to the enhancement of texture degree of melt-spun ribbon and the grain size has no obvious change.

  10. Study of a Mini-Actuator with Permanent Magnets

    Directory of Open Access Journals (Sweden)

    PETRESCU, C.

    2009-10-01

    Full Text Available The paper presents an analytical method for the determination of the magnetic force produced by a mini - actuator with permanent magnets. The results are compared with those obtained by performing a numerical field analysis with COMSOL Multiphysics, showing a very good agreement. The study reveals that the actuator has two equilibrium points, one of which is stable and the other one unstable.

  11. Design and performance of a 1 MW-5 s high temperature superconductor magnetic energy storage system

    Science.gov (United States)

    Morandi, Antonio; Gholizad, Babak; Fabbri, Massimo

    2016-01-01

    The feasibility of a 1 MW-5 s superconducting magnetic energy storage (SMES) system based on state-of-the-art high-temperature superconductor (HTS) materials is investigated in detail. Both YBCO coated conductors and MgB2 are considered. A procedure for the electromagnetic design of the coil is introduced and the final layout is arrived at and compared for the two materials. The choice of the inductance of the coil is carried out as part of the design procedure. Both low-field (3 T) and high-field (8 T) designs are considered for the YBCO. AC losses during a complete charge/discharge cycle at full power are estimated and the cooling power needed for continuous operation is derived. The power conditioning system and control algorithms needed to carry out various operations are discussed in detail. Performances of the SMES system during voltage sag compensation, load leveling and power factor correction are investigated by means of numerical simulation.

  12. Experimental charge density of hematite in its magnetic low temperature and high temperature phases.

    Science.gov (United States)

    Theissmann, R; Fuess, H; Tsuda, K

    2012-09-01

    Structural parameters of hematite (α-Fe(2)O(3)), including the valence electron distribution, were investigated using convergent beam electron diffraction (CBED) in the canted antiferromagnetic phase at room temperature and in the collinear antiferromagnetic phase at 90K. The refined charge density maps are interpreted as a direct result of electron-electron interaction in a correlated system. A negative deformation density was observed as a consequence of closed shell interaction. Positive deformation densities are interpreted as a shift of electron density to antibinding molecular orbitals. Following this interpretation, the collinear antiferromagnetic phase shows the characteristic of a Mott-Hubbard type insulator whereas the high temperature canted antiferromagnetic phase shows the characteristic of a charge transfer insulator. The break of the threefold symmetry in the canted antiferromagnetic phase was correlated to the presence of oxygen-oxygen bonding, which is caused by a shift of spin polarized charge density from iron 3d-orbitals to the oxygen ions. We propose a triangular magnetic coupling in the oxygen planes causing a frustrated triangular spin arrangement with all spins lying in the oxygen planes. This frustrated arrangement polarizes the super-exchange between iron ions and causes the spins located at the iron ions to orient in the same plane, perpendicular to the threefold axis. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Experimental charge density of hematite in its magnetic low temperature and high temperature phases

    Energy Technology Data Exchange (ETDEWEB)

    Theissmann, R., E-mail: ralf.theissmann@kronosww.com [Faculty of Engineering and CeNIDE (Center for NanoIntegration Duisburg-Essen), University of Duisburg-Essen, Bismarckstr. 81, 47057 Duisburg (Germany); Fuess, H. [Institute for Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); Tsuda, K. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, 980-8577 Sendai (Japan)

    2012-09-15

    Structural parameters of hematite ({alpha}-Fe{sub 2}O{sub 3}), including the valence electron distribution, were investigated using convergent beam electron diffraction (CBED) in the canted antiferromagnetic phase at room temperature and in the collinear antiferromagnetic phase at 90 K. The refined charge density maps are interpreted as a direct result of electron-electron interaction in a correlated system. A negative deformation density was observed as a consequence of closed shell interaction. Positive deformation densities are interpreted as a shift of electron density to antibinding molecular orbitals. Following this interpretation, the collinear antiferromagnetic phase shows the characteristic of a Mott-Hubbard type insulator whereas the high temperature canted antiferromagnetic phase shows the characteristic of a charge transfer insulator. The break of the threefold symmetry in the canted antiferromagnetic phase was correlated to the presence of oxygen-oxygen bonding, which is caused by a shift of spin polarized charge density from iron 3d-orbitals to the oxygen ions. We propose a triangular magnetic coupling in the oxygen planes causing a frustrated triangular spin arrangement with all spins lying in the oxygen planes. This frustrated arrangement polarizes the super-exchange between iron ions and causes the spins located at the iron ions to orient in the same plane, perpendicular to the threefold axis. -- Highlights: Black-Right-Pointing-Pointer Quantitative CBED was used to study hematite ({alpha}-Fe2O3). Black-Right-Pointing-Pointer Structure and charge density of both antiferromagnetic phases were investigated. Black-Right-Pointing-Pointer Topological charge density analysis was combined with a Bader analysis. Black-Right-Pointing-Pointer A transition from a Mott-Hubbard to a charge transfer insulator is proposed. Black-Right-Pointing-Pointer A frustrated triangular magnetic coupling in the oxygen planes is proposed.

  14. Structural looseness investigation in slow rotating permanent magnet generators

    DEFF Research Database (Denmark)

    Skrimpas, Georgios Alexandros; Mijatovic, Nenad; Sweeney, Christian Walsted;

    2016-01-01

    Structural looseness in electric machines is a condition influencing the alignment of the machine and thus the overall bearing health. In this work, assessment of the above mentioned failure mode is tested on a slow rotating (running speed equal to 0.7Hz) permanent magnet generator (PMG), while...

  15. The permanent magnet propulsion motor: from infancy to adolescence

    Energy Technology Data Exchange (ETDEWEB)

    Voyce, J.E. [Royal Navy (United Kingdom); Husband, S.M. [Rolls-Royce Strategic Research Centre (United Kingdom); Mattick, D.J. [Rolls-Royce Marine (United Kingdom)

    2000-07-01

    This paper presents an update on the Permanent Magnet Propulsion Motor (PMPM) Technical Demonstrator Programme (TDP). It looks at the history behind the TDP before concentrating on the design and development of the motor. The paper highlights the manufacturing processes involved in building such a novel design, and the motor testing programme, both complete and forthcoming at the time of writing the paper. (authors)

  16. Design Considerations of Permanent Magnet Transverse Flux Machines

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Rasmussen, Peter Omand; Ritchie, Ewen

    2011-01-01

    Permanent magnet transverse flux machine (PMTFM) is well known for its high torque density and is interested in various direct-drive applications. Due to its complicated 3-D flux components, design and design optimization of a PMTFM is more difficult and time consuming than for radial flux...

  17. Compact ECR ion source with permanent magnets for Carbon therapy

    NARCIS (Netherlands)

    Muramatsu, M; Kitagawa, A; Sakamoto, Y; Sato, Y; Yamada, S; Ogawa, H; Drentje, AG; Biri, S; Yoshida, Y

    Ion sources for the medical facilities should have the following characteristics of easy maintenance, low electric power, good stability, and long operation time without trouble (1 year or longer). For this, a 10 GHz compact electron cyclotron resonance ion source (ECRIS) with all permanent magnets

  18. Modeling of Exterior Rotor Permanent Magnet Machines with Concentrated Windings

    NARCIS (Netherlands)

    Vu Xuan, H.

    2012-01-01

    In this thesis modeling, analysis, design and measurement of exterior rotor permanent magnet (PM) machines with concentrated windings are dealt with. Special attention is paid to slotting effect. The PM machine is integrated in flywheel and used for small-scale ship application. Analytical model and

  19. Performance Comparison of Permanent Magnet Linear Actuators of Different Mover Types

    DEFF Research Database (Denmark)

    Ritchie, Ewen; Hinov, K.; Yatchev, I.

    2006-01-01

    A comparative study of permanent magnet linear actuators with different location of the permanent magnet is reported. Three mover types are considered - soft magnetic mover, permanent magnet mover and hybrid mover. Force-stroke characteristics are obtained with the help of finite element models...

  20. Improvement of the propulsion force for HTSC-permanent magnet hybrid magnetically levitated carrying system by using the pinned flux of HTSC

    Science.gov (United States)

    Ikeda, M.; Sasaki, R.; Ueno, T.; Ohashi, S.

    Magnetically levitated carrying system has been developed. In this system, pinning force of high temperature bulk superconductor (HTSC) is used for the levitation and guidance. The magnetic rail is set on the ground, and flux from the magnetic rail is pinned by HTSCs. To increase levitation force, repulsive force of the permanent magnet is used. For the propulsion system, electromagnets are installed on the surface of the magnetic rail. Improvement of the propulsion force is studied. In the previous system, only flux of the permanent magnet of the carrier is used for propulsion. To increase propulsion force, that of the HTSC of the carrier is also used. Using this excitation method, the propulsion force is improved even though total number of the excited coil is the same.

  1. A Cryogenic Magnetostrictive Actuator using a Persistent High Temperature Superconducting Magnet, Part 1: Concept and Design. Part 1; Concept and Design

    Science.gov (United States)

    Horner, Garnett C.; Bromberg, Leslie; Teter, J. P.

    2001-01-01

    Cryogenic magnetostrictive materials, such as rare earth zinc crystals, offer high strains and high forces with minimally applied magnetic fields, making the material ideally suited for deformable optics applications. For cryogenic temperature applications, such as Next Generation Space Telescope (NGST), the use of superconducting magnets offer the possibility of a persistent mode of operation, i.e., the magnetostrictive material will maintain a strain field without power. High temperature superconductors (HTS) are attractive options if the temperature of operation is higher than 10 degrees Kelvin (K) and below 77 K. However, HTS wires have constraints that limit the minimum radius of winding, and even if good wires can be produced, the technology for joining superconducting wires does not exist. In this paper, the design and capabilities of a rare earth zinc magnetostrictive actuator using bulk HTS is described. Bulk superconductors can be fabricated in the sizes required with excellent superconducting properties. Equivalent permanent magnets, made with this inexpensive material, are persistent, do not require a persistent switch as in HTS wires, and can be made very small. These devices are charged using a technique which is similar to the one used for charging permanent magnets, e.g., by driving them into saturation. A small normal conducting coil can be used for charging or discharging. Very fast charging and discharging of HTS tubes, as short as 100 microseconds, has been demonstrated. Because of the magnetic field capability of the superconductor material, a very small amount of superconducting magnet material is needed to actuate the rare earth zinc. In this paper, several designs of actuators using YBCO and BSCCO 2212 superconducting materials are presented. Designs that include magnetic shielding to prevent interaction between adjacent actuators will also be described. Preliminary experimental results and comparison with theory for BSSCO 2212 with a

  2. Rotating permanent magnet excitation for blood flow measurement.

    Science.gov (United States)

    Nair, Sarath S; Vinodkumar, V; Sreedevi, V; Nagesh, D S

    2015-11-01

    A compact, portable and improved blood flow measurement system for an extracorporeal circuit having a rotating permanent magnetic excitation scheme is described in this paper. The system consists of a set of permanent magnets rotating near blood or any conductive fluid to create high-intensity alternating magnetic field in it and inducing a sinusoidal varying voltage across the column of fluid. The induced voltage signal is acquired, conditioned and processed to determine its flow rate. Performance analysis shows that a sensitivity of more than 250 mV/lpm can be obtained, which is more than five times higher than conventional flow measurement systems. Choice of rotating permanent magnet instead of an electromagnetic core generates alternate magnetic field of smooth sinusoidal nature which in turn reduces switching and interference noises. These results in reduction in complex electronic circuitry required for processing the signal to a great extent and enable the flow measuring device to be much less costlier, portable and light weight. The signal remains steady even with changes in environmental conditions and has an accuracy of greater than 95%. This paper also describes the construction details of the prototype, the factors affecting sensitivity and detailed performance analysis at various operating conditions.

  3. A Practical Permanent Magnetic Motor Drive for Hybrid Motorcycle

    Institute of Scientific and Technical Information of China (English)

    崔巍; 江建中; 邵定国; 杨斌

    2003-01-01

    A novel embedded-type permanent magnetic motor for hybrid motorcycle, which employs asymmetric design of eccentric air-gap, is proposed in the paper. This special design of air-gap well conforms to the mono-directional operation characteristic of motorcycle and effectively suppresses the distortion of air-gap magnetic field caused by armature reaction. Hence the torque ripple is reduced. A drive system consisting of the newly-designed Nd-Fe-B permanent magnet synchronous motor and parallel-MOSFET threephase inverter for hybrid motorcycle propulsion is established. Wide-range speed operation is realized through a simple and novel control strategy. Computer simulation is described and experimental results given to verify the practicality of the proposed motor design and control strategy.

  4. Sampling Hyperpolarized Molecules Utilizing a 1 Tesla Permanent Magnetic Field.

    Science.gov (United States)

    Tee, Sui Seng; DiGialleonardo, Valentina; Eskandari, Roozbeh; Jeong, Sangmoo; Granlund, Kristin L; Miloushev, Vesselin; Poot, Alex J; Truong, Steven; Alvarez, Julio A; Aldeborgh, Hannah N; Keshari, Kayvan R

    2016-09-06

    Hyperpolarized magnetic resonance spectroscopy (HP MRS) using dynamic nuclear polarization (DNP) is a technique that has greatly enhanced the sensitivity of detecting (13)C nuclei. However, the HP MRS polarization decays in the liquid state according to the spin-lattice relaxation time (T1) of the nucleus. Sampling of the signal also destroys polarization, resulting in a limited temporal ability to observe biologically interesting reactions. In this study, we demonstrate that sampling hyperpolarized signals using a permanent magnet at 1 Tesla (1T) is a simple and cost-effective method to increase T1s without sacrificing signal-to-noise. Biologically-relevant information may be obtained with a permanent magnet using enzyme solutions and in whole cells. Of significance, our findings indicate that changes in pyruvate metabolism can also be quantified in a xenograft model at this field strength.

  5. Sampling Hyperpolarized Molecules Utilizing a 1 Tesla Permanent Magnetic Field

    Science.gov (United States)

    Tee, Sui Seng; Digialleonardo, Valentina; Eskandari, Roozbeh; Jeong, Sangmoo; Granlund, Kristin L.; Miloushev, Vesselin; Poot, Alex J.; Truong, Steven; Alvarez, Julio A.; Aldeborgh, Hannah N.; Keshari, Kayvan R.

    2016-09-01

    Hyperpolarized magnetic resonance spectroscopy (HP MRS) using dynamic nuclear polarization (DNP) is a technique that has greatly enhanced the sensitivity of detecting 13C nuclei. However, the HP MRS polarization decays in the liquid state according to the spin-lattice relaxation time (T1) of the nucleus. Sampling of the signal also destroys polarization, resulting in a limited temporal ability to observe biologically interesting reactions. In this study, we demonstrate that sampling hyperpolarized signals using a permanent magnet at 1 Tesla (1T) is a simple and cost-effective method to increase T1s without sacrificing signal-to-noise. Biologically-relevant information may be obtained with a permanent magnet using enzyme solutions and in whole cells. Of significance, our findings indicate that changes in pyruvate metabolism can also be quantified in a xenograft model at this field strength.

  6. Bearingless Permanent Magnet Synchronous Motor using Independent Control

    Directory of Open Access Journals (Sweden)

    Normaisharah Mamat

    2015-06-01

    Full Text Available Bearingless permanent magnet synchronous motor (BPMSM combines the characteristic of the conventional permanent magent synchronous motor and magnetic bearing in one electric motor. BPMSM is a kind of high performance motor due to having both advantages of PMSM and magnetic bearing with simple structure, high efficiency, and reasonable cost. The research on BPMSM is to design and analyse BPMSM by using Maxwell 2-Dimensional of ANSYS Finite Element Method (FEM. Independent suspension force model and bearingless PMSM model are developed by using the method of suspension force. Then, the mathematical model of electromagnetic torque and radial suspension force has been developed by using Matlab/Simulink. The relation between force, current, distance and other parameter are determined. This research covered the principle of suspension force, the mathematical model, FEM analysis and digital control system of bearingless PMSM. This kind of motor is widely used in high speed application such as compressors, pumps and turbines.

  7. Development of permanent magnetic refrigerator at room temperature

    Institute of Scientific and Technical Information of China (English)

    HUANG Jiaohong; LIU Jinrong; JIN Peiyu; YAN Hongwei; QIU Jufeng; XU Laizi; ZHANG Jiuxing

    2006-01-01

    A reciprocating magnetic refrigerator was developed based on the active magneticregeneration technology. Rare earth metal Gd and intermetallic compound LaFe11.2Co0.7Si1.1 were used as the magnetic operating materials in the machine. The particles of the magnetic operating materials, with diameter of 0.5- 2 mm and total mass of 950 g, were mounted in the cooling bed. A magnetic field was assembled using NdFeB rare earth permanent magnets. It had the magneticfield space of Φ 34×200 and the magnetic induction of 1.5 T. The water at pH=10 is used as a heat transfer fluid. When the ambient temperature is 296 K, a temperature span of 18 K was achieved after operation of 45 min at a frequency of 0.178 Hz. The temperature span and the output power increase significantly with the increasing velocity of heat transfer.

  8. Study of Permanent Magnet Focusing for Astronomical Camera Tubes

    Science.gov (United States)

    Long, D. C.; Lowrance, J. L.

    1975-01-01

    A design is developed of a permanent magnet assembly (PMA) useful as the magnetic focusing unit for the 35 and 70 mm (diagonal) format SEC tubes. Detailed PMA designs for both tubes are given, and all data on their magnetic configuration, size, weight, and structure of magnetic shields adequate to screen the camera tube from the earth's magnetic field are presented. A digital computer is used for the PMA design simulations, and the expected operational performance of the PMA is ascertained through the calculation of a series of photoelectron trajectories. A large volume where the magnetic field uniformity is greater than 0.5% appears obtainable, and the point spread function (PSF) and modulation transfer function(MTF) indicate nearly ideal performance. The MTF at 20 cycles per mm exceeds 90%. The weight and volume appear tractable for the large space telescope and ground based application.

  9. Magnetic field shimming of a permanent magnet using a combination of pieces of permanent magnets and a single-channel shim coil for skeletal age assessment of children.

    Science.gov (United States)

    Terada, Y; Kono, S; Ishizawa, K; Inamura, S; Uchiumi, T; Tamada, D; Kose, K

    2013-05-01

    We adopted a combination of pieces of permanent magnets and a single-channel (SC) shim coil to shim the magnetic field in a magnetic resonance imaging system dedicated for skeletal age assessment of children. The target magnet was a 0.3-T open and compact permanent magnet tailored to the hand imaging of young children. The homogeneity of the magnetic field was first improved by shimming using pieces of permanent magnets. The residual local inhomogeneity was then compensated for by shimming using the SC shim coil. The effectiveness of the shimming was measured by imaging the left hands of human subjects and evaluating the image quality. The magnetic resonance images for the child subject clearly visualized anatomical structures of all bones necessary for skeletal age assessment, demonstrating the usefulness of combined shimming.

  10. Anisotropic ion heating and tail generation during tearing mode magnetic reconnection in a high-temperature plasma.

    Science.gov (United States)

    Magee, R M; Den Hartog, D J; Kumar, S T A; Almagri, A F; Chapman, B E; Fiksel, G; Mirnov, V V; Mezonlin, E D; Titus, J B

    2011-08-05

    Complementary measurements of ion energy distributions in a magnetically confined high-temperature plasma show that magnetic reconnection results in both anisotropic ion heating and the generation of suprathermal ions. The anisotropy, observed in the C(+6) impurity ions, is such that the temperature perpendicular to the magnetic field is larger than the temperature parallel to the magnetic field. The suprathermal tail appears in the majority ion distribution and is well described by a power law to energies 10 times the thermal energy. These observations may offer insight into the energization process.

  11. Development of a miniature permanent magnetic circuit for nuclear magnetic resonance chip

    Science.gov (United States)

    Lu, Rongsheng; Yi, Hong; Wu, Weiping; Ni, Zhonghua

    2013-07-01

    The existing researches of miniature magnetic circuits focus on the single-sided permanent magnetic circuits and the Halbach permanent magnetic circuits. In the single-sided permanent magnetic circuits, the magnetic flux density is always very low in the work region. In the Halbach permanent magnetic circuits, there are always great difficulties in the manufacturing and assembly process. The static magnetic flux density required for nuclear magnetic resonance(NMR) chip is analyzed based on the signal noise ratio(SNR) calculation model, and then a miniature C-shaped permanent magnetic circuit is designed as the required magnetic flux density. Based on Kirchhoff's law and magnetic flux refraction principle, the concept of a single shimming ring is proposed to improve the performance of the designed magnetic circuit. Using the finite element method, a comparative calculation is conducted. The calculation results demonstrate that the magnetic circuit improved with a single shimming has higher magnetic flux density and better magnetic field homogeneity than the one improved with no shimming ring or double shimming rings. The proposed magnetic circuit is manufactured and its experimental test platform is also built. The magnetic flux density measured in the work region is 0.7 T, which is well coincided with the theoretical design. The spatial variation of the magnetic field is within the range of the instrument error. At last, the temperature dependence of the magnetic flux density produced by the proposed magnetic circuit is investigated through both theoretical analysis and experimental study, and a linear functional model is obtained. The proposed research is crucial for solving the problem in the application of NMR-chip under different environmental temperatures.

  12. An active homopolar magnetic bearing with high temperature superconductor (HTS) coils and ferromagnetic cores

    Science.gov (United States)

    Brown, G. V.; Dirusso, E.; Provenza, A. J.

    1995-01-01

    A proof-of-feasibility demonstration showed that high temperature superconductor (HTS) coils can be used in a high-load, active magnetic bearing in liquid nitrogen. A homopolar radial bearing with commercially wound HTS (Bi 2223) bias and control coils produced over 200 lb (890 N) radial load capacity (measured non-rotating) and supported a shaft to 14000 rpm. The goal was to show that HTS coils can operate stably with ferromagnetic cores in a feedback controlled system at a current density similar to that in Cu in liquid nitrogen. Design compromises permitted use of circular coils with rectangular cross section. Conductor improvements will eventually permit coil shape optimization, higher current density and higher bearing load capacity. The bias coil, wound with non-twisted, multifilament HTS conductor, required negligible power to carry its direct current. The control coils were wound with monofilament HTS sheathed in Ag. These dissipated negligible power for direct current (i.e. for steady radial load components). When an alternating current (AC) was added, the AC component dissipated power which increased rapidly with frequency and quadratically with AC amplitude. In fact at frequencies above about 2 hz, the effective resistance of the control coil conductor actually exceeds that of the silver which is in electrical parallel with the oxide superconductor. This is at least qualitatively understandable in the context of a Bean-type model of flux and current penetration into a Type II superconductor. Fortunately the dynamic currents required for bearing stability are of small amplitude. These results show that while twisted multifilament conductor is not needed for stable levitation, twisted multifilaments will be required to reduce control power for sizable dynamic loads, such as those due to unbalance.

  13. High Temperature Magnetic Properties of Indirect Exchange Spring FePt/M(Cu,C/Fe Trilayer Thin Films

    Directory of Open Access Journals (Sweden)

    Anabil Gayen

    2013-01-01

    Full Text Available We report the investigation of temperature dependent magnetic properties of FePt and FePt(30/M(Cu,C/Fe(5 trilayer thin films prepared by using magnetron sputtering technique at ambient temperature and postannealed at different temperatures. L10 ordering, hard magnetic properties, and thermal stability of FePt films are improved with increasing postannealing temperature. In FePt/M/Fe trilayer, the formation of interlayer exchange coupling between magnetic layers depends on interlayer materials and interface morphology. In FePt/C/Fe trilayer, when the C interlayer thickness was about 0.5 nm, a strong interlayer exchange coupling between hard and soft layers was achieved, and saturation magnetization was enhanced considerably after using interlayer exchange coupling with Fe. In addition, incoherent magnetization reversal process observed in FePt/Fe films changes into coherent switching process in FePt/C/Fe films giving rise to a single hysteresis loop. High temperature magnetic studies up to 573 K reveal that the effective reduction in the coercivity decreases largely from 34 Oe/K for FePt/Fe film to 13 Oe/K for FePt/C(0.5/Fe film demonstrating that the interlayer exchange coupling seems to be a promising approach to improve the stability of hard magnetic properties at high temperatures, which is suitable for high-performance magnets and thermally assisted magnetic recording media.

  14. Method for forming permanent magnets with different polarities for use in microelectromechanical devices

    Science.gov (United States)

    Roesler, Alexander W.; Christenson, Todd R.

    2007-04-24

    Methods are provided for forming a plurality of permanent magnets with two different north-south magnetic pole alignments for use in microelectromechanical (MEM) devices. These methods are based on initially magnetizing the permanent magnets all in the same direction, and then utilizing a combination of heating and a magnetic field to switch the polarity of a portion of the permanent magnets while not switching the remaining permanent magnets. The permanent magnets, in some instances, can all have the same rare-earth composition (e.g. NdFeB) or can be formed of two different rare-earth materials (e.g. NdFeB and SmCo). The methods can be used to form a plurality of permanent magnets side-by-side on or within a substrate with an alternating polarity, or to form a two-dimensional array of permanent magnets in which the polarity of every other row of the array is alternated.

  15. Performance of an Adjustable Strength Permanent Magnet Quadrupole

    CERN Document Server

    Gottschalk, Stephen C; Kangas, Kenneth; Spencer, Cherrill M; Volk, James T

    2005-01-01

    An adjustable strength permanent magnet quadrupole suitable for use in Next Linear Collider has been built and tested. The pole length is 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient * length (GL) is 68.7 Tesla. This paper describes measurements of strength, magnetic centerline and field quality made using an air bearing rotating coil system. The magnetic centerline stability during -20% strength adjustment proposed for beam based alignment was < 0.2 microns. Strength hysteresis was negligible. Thermal expansion of quadrupole and measurement parts caused a repeatable and easily compensated change in the vertical magnetic centerline. Calibration procedures as well as centerline measurements made over a wider tuning range of 100% to 20% in strength useful for a wide range of applications will be described. The impact of eddy currents in the steel poles on the magnetic field during strength adjustments will be reported.

  16. Quantum Hall effect in epitaxial graphene with permanent magnets

    Science.gov (United States)

    Parmentier, F. D.; Cazimajou, T.; Sekine, Y.; Hibino, H.; Irie, H.; Glattli, D. C.; Kumada, N.; Roulleau, P.

    2016-12-01

    We have observed the well-kown quantum Hall effect (QHE) in epitaxial graphene grown on silicon carbide (SiC) by using, for the first time, only commercial NdFeB permanent magnets at low temperature. The relatively large and homogeneous magnetic field generated by the magnets, together with the high quality of the epitaxial graphene films, enables the formation of well-developed quantum Hall states at Landau level filling factors v = ±2, commonly observed with superconducting electro-magnets. Furthermore, the chirality of the QHE edge channels can be changed by a top gate. These results demonstrate that basic QHE physics are experimentally accessible in graphene for a fraction of the price of conventional setups using superconducting magnets, which greatly increases the potential of the QHE in graphene for research and applications.

  17. Improved Nonambipolar Electron Source Operation with Permanent Magnets

    Science.gov (United States)

    Gudmundson, Jesse; Hershkowitz, Noah

    2008-11-01

    The Nonambipolar Electron Source (NES) is a Radio Frequency (rf) plasma-based electron source that does not rely on electron emission at a cathode surface. All electrons are extracted at an electron sheath through a biased ring and all ions are lost radially to a biased Faraday shield. An electromagnet in the original NES has been replaced by a NdFeB permanent magnet array. A portion of the magnet array consists of a ring of radially aligned magnets followed by a ring of axially aligned magnets that produce a peak field of approximately 800 Gauss. Axial magnetic field strength at the extraction ring was increased using an additional ring of axially aligned magnets. Measurement of the magnetic field was in good agreement with field predicted by the FEMM (Finite Element Method Magnetics) code. Optimization of the single turn antenna and biased ring position in the magnetic field will be discussed. At least 15 A of electron current was extracted using a flow rate of 15 sccm Ar at 600 W of rf power at 13.56 MHz. For comparison, the original NES required 1200 W of power to achieve 15 A of extracted current. Compared to the previous coil design, the NdFeB magnets are lighter weight and require no power.

  18. Design Enhancement and Performance Examination of External Rotor Switched Flux Permanent Magnet Machine for Downhole Application

    Science.gov (United States)

    Kumar, R.; Sulaiman, E.; Soomro, H. A.; Jusoh, L. I.; Bahrim, F. S.; Omar, M. F.

    2017-08-01

    The recent change in innovation and employments of high-temperature magnets, permanent magnet flux switching machine (PMFSM) has turned out to be one of the suitable contenders for seaward boring, however, less intended for downhole because of high atmospheric temperature. Subsequently, this extensive review manages the design enhancement and performance examination of external rotor PMFSM for the downhole application. Preparatory, the essential design parameters required for machine configuration are computed numerically. At that point, the design enhancement strategy is actualized through deterministic technique. At last, preliminary and refined execution of the machine is contrasted and as a consequence, the yield torque is raised from 16.39Nm to 33.57Nm while depreciating the cogging torque and PM weight up to 1.77Nm and 0.79kg, individually. In this manner, it is inferred that purposed enhanced design of 12slot-22pole with external rotor is convenient for the downhole application.

  19. Sensorless operation of surface mount permanent magnet AC (PMAC) motors

    Energy Technology Data Exchange (ETDEWEB)

    Toliyat, H.A.; Rahman, K.M.; Shet, D.S.

    1999-12-01

    A sensorless field oriented control scheme for surface mount permanent magnet ac (PMAC) motor with split phase stator windings is presented. This motor is obtained by splitting the phase windings of a conventional three phase motor. The six-phase motor, however is run as a three-phase motor by connecting the split phase stator windings in series, while the taps are made available for voltage measurements. By measuring the terminal voltages and the line currents, absolute position of the permanent magnet ac motor driven by a current regulated PWM inverter with a hysteresis controller is estimated. The estimated position information is independent of the stator resistance, thus this scheme is even applicable at low speeds. Results are presented to show the effectiveness of the new controller, and it is also shown that the position error is negligible.

  20. FUZZY FAULT DETECTION FOR PERMANENT MAGNET SYNCHRONOUS GENERATOR

    Directory of Open Access Journals (Sweden)

    N. Selvaganesan

    2011-07-01

    Full Text Available Faults in engineering systems are difficult to avoid and may result in serious consequences. Effective fault detection and diagnosis can improve system reliability and avoid expensive maintenance. In this paper fuzzy system based fault detection scheme for permanent magnet synchronous generator is proposed. The sequence current components like positive and negative sequence currents are used as fault indicators and given as inputs to fuzzy fault detector. Also, the fuzzy inference system is created and rule base is evaluated, relating the sequence current component to the type of faults. These rules are fired for specific changes in sequence current component and the faults are detected. The feasibility of the proposed scheme for permanent magnet synchronous generator is demonstrated for different types of fault under various operating conditions using MATLAB/Simulink.

  1. A New Torque Control System of Permanent Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Evstratov Andrey

    2017-01-01

    Full Text Available The article describes a new approach to control of permanent magnet synchronous motor drive based on the analysis of the electromechanical transformation. The proposed control system provides quick response and low ripple of the motor torque and flux. To synthesis this control system, the authors put the electromagnetic torque and the modulus of stator flux vector as controlled values and use the Lyapunov’s second method. In addition, the stator voltage constriction and ability of low-pass filtration are taken into account. The investigation of the proposed control system has carried out with the simulation and the experimental research which have confirmed that the proposed control system correspond to all above-mentioned control tasks and the permanent magnet synchronous motor controlled under this system may be recommended to use in robotics.

  2. Study on cogging force of permanent magnet linear synchronous motor

    Institute of Scientific and Technical Information of China (English)

    SHANGGUAN Xuan-feng; YUAN Shi-ying; LI Qing-fu

    2005-01-01

    Presented the methods to obtain the cogging force of permanent magnet linear synchronous motors(PMLSMs), analyzed the characteristics of the cogging force,and provided a basis for reducing the effect of the cogging force. 2-dimensional finite element method(2D FEM) was used to solve the whole motor when its mover was at different position, so that the relation was derived between the cogging force and the mover position. The analysis results show that the cogging force between the two ends of the primary iron-core and the secondary permanent magnets (PMs) is sinusoidal function of the mover position under certain conditions only. Two proposed methods,namely direct and indirect methods, are applied to calculate the cogging force between the primary iron-core teeth and the secondary PMs. The agreement of the two methods is validated.

  3. New Cogging Torque Reduction Methods for Permanent Magnet Machine

    Science.gov (United States)

    Bahrim, F. S.; Sulaiman, E.; Kumar, R.; Jusoh, L. I.

    2017-08-01

    Permanent magnet type motors (PMs) especially permanent magnet synchronous motor (PMSM) are expanding its limbs in industrial application system and widely used in various applications. The key features of this machine include high power and torque density, extending speed range, high efficiency, better dynamic performance and good flux-weakening capability. Nevertheless, high in cogging torque, which may cause noise and vibration, is one of the threat of the machine performance. Therefore, with the aid of 3-D finite element analysis (FEA) and simulation using JMAG Designer, this paper proposed new method for cogging torque reduction. Based on the simulation, methods of combining the skewing with radial pole pairing method and skewing with axial pole pairing method reduces the cogging torque effect up to 71.86% and 65.69% simultaneously.

  4. Photovoltaic-wind hybrid system for permanent magnet DC motor

    Science.gov (United States)

    Nasir, M. N. M.; Lada, M. Y.; Baharom, M. F.; Jaafar, H. I.; Ramani, A. N.; Sulaima, M. F.

    2015-05-01

    Hybrid system of Photovoltaic (PV) - Wind turbine (WT) generation has more advantages and reliable compared to PV or wind turbine system alone. The aim of this paper is to model and design hybrid system of PV-WT supplying 100W permanent-magnet dc motor. To achieve the objective, both of PV and WT are connected to converter in order to get the same source of DC supply. Then both sources were combined and straightly connected to 100W permanent magnet dc motor. All the works in this paper is only applied in circuit simulator by using Matlab Simulink. The output produced from each converter is expected to be suit to the motor specification. The output produced from each renewable energy system is as expected to be high as it can support the motor if one of them is breakdown

  5. Cogging torque reduction for interior permanent magnet synchronous motors

    OpenAIRE

    Tost Candel, Miquel

    2015-01-01

    Interior permanent magnet synchronous machines show a good range of behaviours, which make these kinds of machines good candidates for an electromechanical energy conversion. However, in order to improve their accuracy in their torque responses, the cogging torque and torque ripple phenomena should be mitigated to obtain better performance of the machine. In order to reduce the cogging torque and torque ripple, control techniques as well as geometric parameters of the machine have to be im...

  6. Studies Directed Toward New and Improved Permanent Magnet Materials.

    Science.gov (United States)

    1994-09-28

    electric motors and generators. At present there are only 3 permanent magnet materials in widespread use - SmCo5, Nd2Fe14B and SmCo5-Sm2Co17. Each has...a third of the effort has been devoted to effecting improvements in existing materials which occur in the SmCo5 or Nd2Fe14B structures. Materials

  7. Induction Motors Versus Permanent-Magnet Actuators for Aerospace Applications

    OpenAIRE

    Kakosimos, Panagiotis E.; Sarigiannidis, Athanasios G.; Beniakar, Minos E.; Kladas, Antonios G.; Gerada, C

    2014-01-01

    This paper introduces a comparative study on the design of aerospace actuators concerning Induction Motor (IM) and Permanent Magnet Motor (PMM) technologies. In the analysis undertaken, the two candidate configurations are evaluated in terms of both their electromagnetic and thermal behavior in a combined manner. On a first step, the basic dimensioning of the actuators and their fundamental operational characteristics are determined via a time-stepping Finite Element (FE) analysis. The consid...

  8. Permanent magnet brushless motor control based on ADRC

    Directory of Open Access Journals (Sweden)

    Li Xiaokun

    2016-01-01

    Full Text Available Permanent magnet brushless motor is a nonlinear system with multiple variables, the mathematical model of Permanent magnet brushless motor is difficult to establish, and since that the classic PID control is hard to precisely control the motor. Active disturbance rejection control (ADRC technique is a new nonlinear controller which does not depend on the system model. It is starting from the classic PID control, and establishing the loop control system by error negative feedback, the ESO(extended state observer observing system which comes from the observer theory of modern control theory to observe internal and external perturbations. ADRC inherits the advantages of PID with little overshoot, high convergence speed, high accuracy, strong anti-interference ability and other characteristics, and it has a strong disturbance adaptability and robustness as for the uncertainty perturbation and their internal disturbance of control objects. Therefore, This paper attempts to use Active disturbance rejection control(ADRC, in order to improve the control of permanent magnet brushless motor. In this design of control system, the simulation of the system is realized based on MATLAB, and then the discrete control algorithm is transplanted to the embedded system to control the permanent magnet brushless DC motor (PMBLDCM. The control system is implemented on the DSP-F28335 digital signal processor, and the DSP also provides the functions like voltage and current AD sampling, PWM driver generation, speed and rotor position calculation, etc. The simulation and experiment results indicate that, the system has good dynamic performance and anti-disturbance performance.

  9. Speed Regulator for Permanent Magnet DC Boring Machine

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper a variable-speed system for a loaded permanent magnet direct current boring machine (PMDCBM) is described in details. The voltage adjustment of PMDCBM is accomplished by means of solid state switch with a high gain Darlington transistor. The device designed possesses good variable speed characteristic and Iow loss at low speed. The speed can be regulated automatically to hold at an ideal value according to the load.

  10. UCLA-KIAE focusing permanent magnet undulator for SASE experiment

    Science.gov (United States)

    Osmanov, N.; Tolmachev, S.; Varfolomeev, A.; Varfolomeev, A. A.; Frigola, P.; Hogan, M.; Pellegrini, C.; Carr, R.; Lidia, S.

    1998-02-01

    A description of a new 2 m undulator is presented which was specially designed and manufactured for a SASE mode FEL experiment. It is a one section two plane focusing permanent magnet construction. The uniform period length is 2.06 cm, total number of periods is 98. The peak field on the axis is 5.4 kG for a 5 mm gap.

  11. Cogging torque mitigation of modular permanent magnet machines

    OpenAIRE

    Li, G. J.; Ren, B.; Zhu, Z-Q.; Li, Y X; Ma, J.

    2015-01-01

    This paper proposes a novel cogging torque mitigation method for modular permanent magnet (PM) machines with flux gaps in alternate stator teeth. The slot openings of the modular PM machines are divided into two groups in a special way. By shifting the slot openings of two groups in opposite directions with the same angle, the machine cogging torque can be significantly reduced. Analytical formula of the desired shift angle is derived, and can be applicable to other modular machines with diff...

  12. Modular Permanent Magnet Machines with Alternate Teeth Having Tooth Tips

    OpenAIRE

    Li, G. J.; Zhu, Z.Q.; Foster, M. P.; Stone, D. A.; Zhan, H.L.

    2015-01-01

    This paper presents single layer modular permanent magnet machines with either wound or unwound teeth with tooth tips. The structures with wound teeth having tooth tips are suitable for modular machines with slot number higher than pole number to compensate for the drop in winding factor due to the flux gaps in alternate stator teeth, accordingly to maintain or even to increase their average torques. However, the structures with unwound teeth having tooth tips are suitable for modular machine...

  13. A permanent magnet electron beam phase-shifter

    Energy Technology Data Exchange (ETDEWEB)

    Novikov, G.A. E-mail: trower@naxs.net; Ermakov, A.N.; Pakhomov, N.I.; Semyachkin, V.K.; Shvedunov, V.I.; Skachkov, V.S.; Tyurin, S.A

    2004-05-21

    We describe here the design and construction of a permanent magnet-based electron beam phase-shifter now operating in our 70 MeV Race-Track Microtron (P. Lucas, S. Webber (Eds.), Proceedings of the 2001 Particle Accelerator Conference, Vol. 4, IEEE, Piscataway, NJ, 2001, p. 2596; L. Gennary (Ed.), Proceedings of the 1995 Particle Accelerator Conference, Vol. 2, IEEE, Piscataway, NJ, 1996, p. 807)

  14. Simulation of dynamics of a permanent magnet linear actuator

    DEFF Research Database (Denmark)

    Yatchev, Ivan; Ritchie, Ewen

    2010-01-01

    Comparison of two approaches for the simulation of the dynamic behaviour of a permanent magnet linear actuator is presented. These are full coupled model, where the electromagnetic field, electric circuit and mechanical motion problems are solved simultaneously, and decoupled model, where first...... flexibility when the actuator response is required to be estimated for different external conditions, e.g. external circuit parameters or mechanical loads....

  15. Noncontact Laser Calorimetry of High Temperature Melts in a Static Magnetic Field

    Science.gov (United States)

    Fukuyama, Hiroyuki; Kobatake, Hidekazu; Tsukada, Takao; Awaji, Satoshi

    Numerical simulations are widely used for high value-added materials processing such as semiconductor crystal growth, casting of super high-temperature alloys for a jet-engine turbine blade, and for welding in automobile manufacturing [1, 2]. Process modeling involving a liquid-to-solid transition requires precise thermophysical properties of materials in the solid and liquid state at temperatures near their melting points. However, high-temperature materials such as liquid silicon are chemically reactive and are easily contaminated by their containers and contact materials. Therefore, it remains extremely difficult to measure the thermophysical properties of high-temperature liquids. Especially, the thermal conductivity of a high-temperature liquid is a difficult property to measure because of the existence of the buoyancy and Marangoni convections in the liquid. Not only from process modeling but also from a scientific perspective, thermal conductivity data of high-temperature metallic or semiconductor liquids are important to investigate whether the Wiedemann—Franz law [3] is applicable to them.

  16. Simulation of dynamics of a permanent magnet linear actuator

    DEFF Research Database (Denmark)

    Yatchev, Ivan; Ritchie, Ewen

    2010-01-01

    Comparison of two approaches for the simulation of the dynamic behaviour of a permanent magnet linear actuator is presented. These are full coupled model, where the electromagnetic field, electric circuit and mechanical motion problems are solved simultaneously, and decoupled model, where first...... a set of static magnetic filed analysis is carried out and then the electric circuit and mechanical motion equations are solved employing bi-cubic spline approximations of the field analysis results. The results show that the proposed decoupled model is of satisfactory accuracy and gives more...

  17. Permanent magnetic ferrite based power-tunable metamaterials

    Science.gov (United States)

    Zhang, Guanqiao; Lan, Chuwen; Gao, Rui; Zhou, Ji

    2017-08-01

    Power-tunable metamaterials based on barium permanent magnetic ferrite have been proposed and fabricated in this research. Scattering parameter measurements confirm a shift in resonant frequency in correlation to changes in incident electromagnetic power within microwave frequency band. The tunable phenomenon represented by a blue-shift in transmission spectra in the metamaterials array can be attributed to a decrease in saturation magnetization resulting from FMR-induced temperature elevation upon resonant conditions. This power-dependent behavior offers a simple and practical route towards dynamically fine-tunable ferrite metamaterials.

  18. A clip-on Zeeman slower using toroidal permanent magnets.

    Science.gov (United States)

    Krzyzewski, S P; Akin, T G; Dahal, Parshuram; Abraham, E R I

    2014-10-01

    We present the design of a zero-crossing Zeeman slower for (85)Rb using rings of flexible permanent magnets. The design is inexpensive, requires no power or cooling, and can be easily attached and removed for vacuum maintenance. We show theoretically that such a design can reproduce a magnetic field profile of a standard zero-crossing Zeeman slower. Experimental measurements of a prototype and comparisons to theoretical simulations demonstrate the feasibility of the design and point toward future improvements. Simulations show an atom flux similar to other Zeeman slowers.

  19. Multipole shimming of permanent magnets using harmonic corrector rings.

    Science.gov (United States)

    Jachmann, R C; Trease, D R; Bouchard, L-S; Sakellariou, D; Martin, R W; Schlueter, R D; Budinger, T F; Pines, A

    2007-03-01

    Shimming systems are required to provide sufficient field homogeneity for high resolution nuclear magnetic resonance (NMR). In certain specialized applications, such as rotating-field NMR and mobile ex situ NMR, permanent magnet-based shimming systems can provide considerable advantages. We present a simple two-dimensional shimming method based on harmonic corrector rings which can provide arbitrary multipole order shimming corrections. Results demonstrate, for example, that quadrupolar order shimming improves the linewidth by up to an order of magnitude. An additional order of magnitude reduction is in principle achievable by utilizing this shimming method for z-gradient correction and higher order xy gradients.

  20. Two dimensional model of a permanent magnet spur gear

    DEFF Research Database (Denmark)

    Jørgensen, Frank Thorleif; Andersen, Torben Ole; Rasmussen, Peter Omand

    2005-01-01

    This paper presents calculation and measurement results of a high-performance permanent-magnetic gear. The analyzed permanent-magnetic gear has a gear ratio of 5.5 and is able to deliver 27 N/spl middot/m. The analysis has shown that special attention needs to be paid to the system where the gear...... is to be installed because of a low natural torsion spring constant. The analyzed gear was also constructed in practice in order to validate the analysis and predict the efficiency. The measured torque from the magnetic gear was only 16 N/spl middot/m reduced by the large end-effects. A systematic analysis...... of the loss components in the magnetic gear is also performed in order to figure out why the efficiency for the actual construction was only 81%. A large magnetic loss component originated in the bearings, where an unplanned extra bearing was necessary due to mechanical problems. Without the losses...

  1. Inspired by nature: investigating tetrataenite for permanent magnet applications.

    Science.gov (United States)

    Lewis, L H; Mubarok, A; Poirier, E; Bordeaux, N; Manchanda, P; Kashyap, A; Skomski, R; Goldstein, J; Pinkerton, F E; Mishra, R K; Kubic, R C; Barmak, K

    2014-02-12

    Chemically ordered L10-type FeNi, also known as tetrataenite, is under investigation as a rare-earth-free advanced permanent magnet. Correlations between crystal structure, microstructure and magnetic properties of naturally occurring tetrataenite with a slightly Fe-rich composition (~ Fe55Ni44) obtained from the meteorite NWA 6259 are reported and augmented with computationally derived results. The tetrataenite microstructure exhibits three mutually orthogonal crystallographic variants of the L10 structure that reduce its remanence; nonetheless, even in its highly unoptimized state tetrataenite provides a room-temperature coercivity of 95.5 kA m(-1) (1200 Oe), a Curie temperature of at least 830 K and a largely temperature-independent anisotropy that preliminarily point to a theoretical magnetic energy product exceeding (BH)max = 335 kJ m(-3) (42 MG Oe) and approaching those found in today's best rare-earth-based magnets.

  2. Torque Characteristics of Saturated Permanent-Magnet Synchronous Motors

    Science.gov (United States)

    Takahashi, Akeshi; Kikuchi, Satoshi; Wakui, Shinichi; Mikami, Hiroyuki; Ide, Kazumasa; Shima, Kazuo

    The evaluation of torque characteristics in a saturated magnetic field for permanent-magnet (PM) synchronous motors is presented. The torque saturation characteristics of non-salient and salient pole machines are investigated by finite element analysis and measurement. Thus, it is found that the torque saturation originates in the magnetic saturation in both the stator teeth, which are located on the leading position toward the direct axis, and in the stator back yoke, which is located on the lagging position toward the direct axis. This mechanism can also explain the reason for the significant torque saturation in the salient-pole machine; the higher inductance of the quadrature axis of the salient-pole machine causes a significant magnetic saturation in the stator back yoke. Therefore, less saliency or a wider back yoke can improve the torque saturation.

  3. Magnetic-Field-Enhanced Incommensurate Magnetic Order in the Underdoped High-Temperature Superconductor YBa2Cu3O6.45

    DEFF Research Database (Denmark)

    Haug, D.; Hinkov, V.; Suchaneck, A.

    2009-01-01

    We present a neutron-scattering study of the static and dynamic spin correlations in the underdoped high-temperature superconductor YBa2Cu3O6.45 in magnetic fields up to 15 T. The field strongly enhances static incommensurate magnetic order at low temperatures and induces a spectral-weight shift...

  4. Optimization of Magnet Arrangement in Double-Layer Interior Permanent-Magnet Motors

    Science.gov (United States)

    Yamazaki, Katsumi; Kitayuguchi, Kazuya

    The arrangement of permanent magnets in double-layer interior permanent-magnet motors is optimized for variable-speed applications. First, the arrangement of magnets is decided by automatic optimization. Next, the superiority of the optimized motor is discussed by the d- and q-axis equivalent circuits that consider the magnetic saturation of the rotor core. Finally, experimental verification is carried out by using a prototype motor. It is confirmed that the maximum torque of the optimized motor under both low speed and high speed conditions are higher than those of conventional motors because of relatively large q-axis inductance and small d-axis inductance.

  5. High Temperature Superconducting Magnetic Energy Storage and Its Power Control Technology

    Institute of Scientific and Technical Information of China (English)

    Xiao-Yuan Chen; Jian-Xun Jin; Kai-Meng Ma; Ju Wen; Ying Xin; Wei-Zhi Gong; An-Lin Ren; Jing-Yin Zhang

    2008-01-01

    High temperature superconducting (HTS) power inductor and its control technology have been studied and analyzed in the paper. Based on the results of simulations and practical experiments, a controlled release scheme has been proposed and verified for developing a practical HTS SMES prototype.

  6. Magnetic sensor with silicon on insulator structure for high temperature applications; SOI kozo wo mochiita koon`yo jiki sensor

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Y.; Kawai, H.; Terada, T.; Kawahito, S.; Ishida, M.; Nakamura, T. [Toyohashi University of Technology, Aichi (Japan)

    1996-09-20

    To enable stable magnetic measurement in high temperature surroundings, a Hall cell of the SOI structure (with a single-crystal Si layer formed on an insulating film) was experimentally fabricated, and its characteristics as a magnetic sensor were examined. This element can be mass-produced by use of the current semiconductor manufacturing technology. In the conventional method of element isolation using the pn-junction, backward leak currents across the pn-junction grow large at high temperatures, reducing sensitivity and increasing offset voltage (the Hall voltage at zero magnetic field) to disable the elements. Under the circumstances, an SOI structure in which elements are isolated by an SiO2 film were studied. Sensitivity and temperature characteristics are dependent on donor concentration. But there is a relationship of trade-off between sensitivity and the usable temperature range, and this means that a donor concentration fit for the given purpose needs be chosen. To inhibit the generation of the offset voltage, Hall element shapes and chip bonding methods were studied, and a magnetic sensor with an offset variation not more than {plus_minus}3mV was obtained. In an SOI magnetic sensor, the temperature range in which sensitivity remains constant expands as donor concentration is enhanced, and this permits the use of the SOI magnetic sensor in higher-temperature operations. 6 refs., 13 figs., 1 tab.

  7. Factors affecting characterization of bulk high-temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Hull, J.R. [Argonne National Lab., IL (United States). Energy Technology Div.

    1997-11-01

    Three major factors affect the characterization of bulk high-temperature superconductors in terms of their levitation properties during interaction with permanent magnets. First, the appropriate parameter for the permanent magnet is internal magnetization, not the value of the magnetic field measured at the magnet`s surface. Second, although levitation force grows with superconductor thickness and surface area, for a given permanent magnet size, comparison of levitation force between samples is meaningful when minimum values are assigned to the superconductor size parameters. Finally, the effect of force creep must be considered when time-averaging the force measurements. In addition to levitational force, the coefficient of friction of a levitated rotating permanent magnet may be used to characterize the superconductor.

  8. High-Performance Permanent Magnets for Energy-Efficient Devices

    Science.gov (United States)

    Hadjipanayis, George

    2012-02-01

    Permanent magnets (PMs) are indispensable for many commercial applications including the electric, electronic and automobile industries, communications, information technologies and automatic control engineering. In most of these applications, an increase in the magnetic energy density of the PM, usually presented via the maximum energy product (BH)max, immediately increases the efficiency of the whole device and makes it smaller and lighter. Worldwide demand for high performance permanent magnets has increased dramatically in the past few years driven by hybrid and electric cars, wind turbines and other power generation systems. New energy challenges in the world require devices with higher energy efficiency and minimum environmental impact. The potential of 3d-4f compounds which revolutionized the PM science and technology is almost fully utilized, and the supply of 4f rare earth elements does not seem to be much longer assured. This talk will address the major principles guiding the development of PMs and overview state-of-the-art theoretical and experimental research. Recent progress in the development of nanocomposite PMs, consisting of a fine (at the scale of the magnetic exchange length) mixture of phases with high magnetization and large magnetic hardness will be discussed. Fabrication of such PMs is currently the most promising way to boost the (BH)max, while simultaneously decreasing, at least partially, the reliance on the rare earth elements. Special attention will be paid to the impact which the next-generation high-(BH)max magnets is expected to have on existing and proposed energy-saving technologies.

  9. Characterization of high temperature superconductor cables for magnet toroidal field coils of the DEMO fusion power plant

    Energy Technology Data Exchange (ETDEWEB)

    Bayer, Christoph M.

    2017-05-01

    Nuclear fusion is a key technology to satisfy the basic demand for electric energy sustainably. The official EUROfusion schedule foresees a first industrial DEMOnstration Fusion Power Plant for 2050. In this work several high temperature superconductor sub-size cables are investigated for their applicability in large scale DEMO toroidal field coils. Main focus lies on the electromechanical stability under the influence of high Lorentz forces at peak magnetic fields of up to 12 T.

  10. Discrete Current Control Strategy of Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Yan Dong

    2013-01-01

    Full Text Available A control strategy of permanent magnet synchronous motors (PMSMs, which is different from the traditional vector control (VC and direct torque control (DTC, is proposed. Firstly, the circular rotating magnetic field is analyzed on the simplified model and discredited into stepping magnetic field. The stepping magnetomotive force will drive the rotor to run as the stepping motor. Secondly, the stator current orientation is used to build the control model instead of rotor flux orientation. Then, the discrete current control strategy is set and adopted in positioning control. Three methods of the strategy are simulated in computer and tested on the experiment platform of PMSM. The control precision is also verified through the experiment.

  11. Innovative Sensors for Pipeline Crawlers: Rotating Permanent Magnet Inspection

    Energy Technology Data Exchange (ETDEWEB)

    J. Bruce Nestleroth; Richard J. Davis; Stephanie Flamberg

    2006-09-30

    Internal inspection of pipelines is an important tool for ensuring safe and reliable delivery of fossil energy products. Current inspection systems that are propelled through the pipeline by the product flow cannot be used to inspect all pipelines because of the various physical barriers they may encounter. To facilitate inspection of these ''unpiggable'' pipelines, recent inspection development efforts have focused on a new generation of powered inspection platforms that are able to crawl slowly inside a pipeline and can maneuver past the physical barriers that limit internal inspection applicability, such as bore restrictions, low product flow rate, and low pressure. The first step in this research was to review existing inspection technologies for applicability and compatibility with crawler systems. Most existing inspection technologies, including magnetic flux leakage and ultrasonic methods, had significant implementation limitations including mass, physical size, inspection energy coupling requirements and technology maturity. The remote field technique was the most promising but power consumption was high and anomaly signals were low requiring sensitive detectors and electronics. After reviewing each inspection technology, it was decided to investigate the potential for a new inspection method. The new inspection method takes advantage of advances in permanent magnet strength, along with their wide availability and low cost. Called rotating permanent magnet inspection (RPMI), this patent pending technology employs pairs of permanent magnets rotating around the central axis of a cylinder to induce high current densities in the material under inspection. Anomalies and wall thickness variations are detected with an array of sensors that measure local changes in the magnetic field produced by the induced current flowing in the material. This inspection method is an alternative to the common concentric coil remote field technique that induces

  12. A SQP optimization method for shimming a permanent MRI magnet

    Institute of Scientific and Technical Information of China (English)

    Zhe Jin; Xing Tang; Bin Meng; Donglin Zu; Weimin Wang

    2009-01-01

    Based on the sequential quadratic programming (SQP) method, a new approach is presented in this paper to gain a uniform magnetic field for a permanent MRI magnet with biplanar poles. First, the adopted shimming piece is modeled as a magnetic dipole moment to calculate its effect on the background field over the imaging region of interest. Then, the SQP method is utilized to determine the ideal solution for the shimming equation. Finally, the ideal solution is discrete, and the quantization error control technique is used for special cases. This new method helps to reduce the inhomogeneity from 1234.5 ppm to 21.4 ppm over a 36 cm diameter spherical volume (DSV), within hours in practical shimming work.

  13. Virtual test system for permanent-magnet DC motor

    Institute of Scientific and Technical Information of China (English)

    崔淑梅; 王悦; 柴凤; 吴红星; 刘宝廷; 程树康

    2003-01-01

    In order to obtain the primary parameters and operating characteristics of a DC motor without directlymeasuring its torque and rational speed, it is proposed to use a PC and a data acquisition card to acquire boththe dynamic and static data of armature current to establish the performance of a DC permanent-magnet motor.The accuracy and validity of this virtual test system proposed were verified by comparing the measurements madewith the system proposed with the measurements made with conventional torque meters. It is concluded from theresults of comparison that from the mathematic model established for the DC permant-magnet motors, both majorparameters and operating characteristics can be directly established for the DC motors without measuring theirtorques and rotational speed, a perfect on-line measurement and test system has been established for the DCpermanent-magnet motors using the theory of virtual test system. The system proposed features shorter test time,higher efficiency and lower cost.

  14. Simulation of magnetic induction distribution in a coaxial linear motor with axial and radial direction of permanent magnets magnetization

    Directory of Open Access Journals (Sweden)

    G.M. Golenkov

    2014-03-01

    Full Text Available The paper presents results of computer simulation and experimental study of magnetic induction distribution in a coaxial linear motor air gap throughout the length of the runner active part at different heights of the air gap between the runner and the inductor magnetic core for motors with axial and radial direction of the permanent magnets magnetization.

  15. High frequency, high temperature specific core loss and dynamic B-H hysteresis loop characteristics of soft magnetic alloys

    Science.gov (United States)

    Wieserman, W. R.; Schwarze, G. E.; Niedra, J. M.

    1990-01-01

    Limited experimental data exists for the specific core loss and dynamic B-H loops for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H loop characteristics of Supermalloy and Metglas 2605SC over the frequency range of 1 to 50 kHz and temperature range of 23 to 300 C under sinusoidal voltage excitation. The experimental setup used to conduct the investigation is described. The effects of the maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined.

  16. Design method and magnetic field analysis of axial-magnetized permanent magnet micromotor

    Institute of Scientific and Technical Information of China (English)

    YANG Jiewei; WU Yihui; JIA Hongguang; ZHANG Ping; WANG Shurong

    2007-01-01

    To investigate the impact of size on its performance in designing an axial-magnetized permanent magnet micromotor,the finite element method is adopted to simulate the magnetic field of the dual rotor motor,and the flux density wave form distributed in the airgap is obtained.The influence of the external dimensions,pole numbers and magnet thicknesses of the rotor,and the airgap distances on the flux density,are analyzed and analytical results are given.With the increase of the airgap distance,the flux density under more poles reduces more quickly than under fewer poles.With the increase of the magnet thickness,the flux density is a rising curve,and after the magnet thickness attains a certain point,the flux density is almost a constant.While reducing the diameter of the rotor,the decrease of the flux density slows down as magnet thickness is reduced.To avoid having a seriously distorted waveform,the distance between inner and outer radii of the rotor must be larger than 1.5 millimeter.Results of the magnetic field analysis can guide a microminiaturization of the motor.Moreover,the results are analyzed theoretically and the simulated values are almost consistent with the experimental values.

  17. [Development of RF coil of permanent magnet mini-magnetic resonance imager and mouse imaging experiments].

    Science.gov (United States)

    Hou, Shulian; Xie, Huantong; Chen, Wei; Wang, Guangxin; Zhao, Qiang; Li, Shiyu

    2014-10-01

    In the development of radio frequency (RF) coils for better quality of the mini-type permanent magnetic resonance imager for using in the small animal imaging, the solenoid RF coil has a special advantage for permanent magnetic system based on analyses of various types.of RF coils. However, it is not satisfied for imaging if the RF coils are directly used. By theoretical analyses of the magnetic field properties produced from the solenoid coil, the research direction was determined by careful studies to raise further the uniformity of the magnetic field coil, receiving coil sensitivity for signals and signal-to-noise ratio (SNR). The method had certain advantages and avoided some shortcomings of the other different coil types, such as, birdcage coil, saddle shaped coil and phased array coil by using the alloy materials (from our own patent). The RF coils were designed, developed and made for keeled applicable to permanent magnet-type magnetic resonance imager, multi-coil combination-type, single-channel overall RF receiving coil, and applied for a patent. Mounted on three instruments (25 mm aperture, with main magnetic field strength of 0.5 T or 1.5 T, and 50 mm aperture, with main magnetic field strength of 0.48 T), we performed experiments with mice, rats, and nude mice bearing tumors. The experimental results indicated that the RF receiving coil was fully applicable to the permanent magnet-type imaging system.

  18. Toroidal-Core Microinductors Biased by Permanent Magnets

    Science.gov (United States)

    Lieneweg, Udo; Blaes, Brent

    2003-01-01

    The designs of microscopic toroidal-core inductors in integrated circuits of DC-to-DC voltage converters would be modified, according to a proposal, by filling the gaps in the cores with permanent magnets that would apply bias fluxes (see figure). The magnitudes and polarities of the bias fluxes would be tailored to counteract the DC fluxes generated by the DC components of the currents in the inductor windings, such that it would be possible to either reduce the sizes of the cores or increase the AC components of the currents in the cores without incurring adverse effects. Reducing the sizes of the cores could save significant amounts of space on integrated circuits because relative to other integrated-circuit components, microinductors occupy large areas - of the order of a square millimeter each. An important consideration in the design of such an inductor is preventing magnetic saturation of the core at current levels up to the maximum anticipated operating current. The requirement to prevent saturation, as well as other requirements and constraints upon the design of the core are expressed by several equations based on the traditional magnetic-circuit approximation. The equations involve the core and gap dimensions and the magnetic-property parameters of the core and magnet materials. The equations show that, other things remaining equal, as the maximum current is increased, one must increase the size of the core to prevent the flux density from rising to the saturation level. By using a permanent bias flux to oppose the flux generated by the DC component of the current, one would reduce the net DC component of flux in the core, making it possible to reduce the core size needed to prevent the total flux density (sum of DC and AC components) from rising to the saturation level. Alternatively, one could take advantage of the reduction of the net DC component of flux by increasing the allowable AC component of flux and the corresponding AC component of current

  19. Comparative M-H Characteristics of 1-5 and 2-17 Type Samarium-Cobalt Permanent Magnets to 300 C

    Science.gov (United States)

    Niedra, Janis M.

    1994-01-01

    Recent consideration of the use of permanent magnets in space power converters at heat rejection temperatures exceeding 250 C and in miniature high temperature actuators is supporting a search for permanent magnets resistant to demagnetizing forces at high temperature. The present paper investigates the short-term demagnetization resistance to applied bucking fields and at temperatures up to 300 C of SmCo5 type magnets, in the form of 1-cm cubes, from several commercial sources. Quasistatic, 2nd quadrant M-H data taken at selected temperatures are the source of derived plots which are then compared to similar data for previously tested Sm2Co17 type magnets. The 1-5 magnet remanence tends to be about 1.5 kG below that of the 2-17 magnets throughout the temperature range. However, the intrinsic coercivities and M-H curve 'knee-fields' seen in particular 1-5 magnets were considerably above those seen previously in the 2-17 magnets. This superior resistance to demagnetizing fields attainable in 1-5 magnets is also illustrated by safe operating area plots based on the knee-field, the magnetic induction swing and temperature. Comments are made on the possibility that a remanence versus knee-field tradeoff can make 1-5 material competitive with 2-17 in applications where a magnet has to withstand large bucking fields at high temperature.

  20. Sample Size Effect of Magnetomechanical Response for Magnetic Elastomers by Using Permanent Magnets

    Directory of Open Access Journals (Sweden)

    Tsubasa Oguro

    2017-01-01

    Full Text Available The size effect of magnetomechanical response of chemically cross-linked disk shaped magnetic elastomers placed on a permanent magnet has been investigated by unidirectional compression tests. A cylindrical permanent magnet with a size of 35 mm in diameter and 15 mm in height was used to create the magnetic field. The magnetic field strength was approximately 420 mT at the center of the upper surface of the magnet. The diameter of the magnetoelastic polymer disks was varied from 14 mm to 35 mm, whereas the height was kept constant (5 mm in the undeformed state. We have studied the influence of the disk diameter on the stress-strain behavior of the magnetoelastic in the presence and in the lack of magnetic field. It was found that the smallest magnetic elastomer with 14 mm diameter did not exhibit measurable magnetomechanical response due to magnetic field. On the opposite, the magnetic elastomers with diameters larger than 30 mm contracted in the direction parallel to the mechanical stress and largely elongated in the perpendicular direction. An explanation is put forward to interpret this size-dependent behavior by taking into account the nonuniform field distribution of magnetic field produced by the permanent magnet.

  1. Analysis of Vibration and Acoustic Noise in Permanent Magnet Motors.

    Science.gov (United States)

    Hwang, Sangmoon

    The drive motor is a frequent source of vibration and acoustic noise in many precision spindle motors. One of the electromagnetic sources of vibration in permanent magnet motors is the torque ripple, consisting of the reluctance torque and electromagnetic torque fluctuation. This type of vibration is becoming more serious with the advent of new high-grade magnets with increased flux density. Acoustic noise of electromagnetic origin is difficult to predict and its exact mechanism is unclear. The mechanism of noise generation should be revealed to design a quieter motor which is the modern customer's demand. For motor operation at low speeds and loads, torque ripple due to the reluctance torque is often a source of vibration and control difficulty. The reluctance torque in a motor was calculated from the flux density by a finite element method and the Maxwell stress method. Effects of design parameters, such as stator slot width, permanent slot width, airgap length and magnetization direction, were investigated. Magnet pole shaping, by gradually decreasing the magnet thickness toward edges, yields a sinusoidal shape of the reluctance torque with reduced harmonics, thus reducing the vibration. This dissertation also presents two motor design techniques: stator tooth notching and rotor pole skewing with magnet pole shaping, and the effect of each method on the output torque. The analysis shows that the reluctance torque can be nearly eliminated by the suggested designs, with minimal sacrifice of the output torque. In permanent magnet DC motors, the most popular design type is the trapezoidal back electro-motive force (BEMF), for switched DC controllers. It is demonstrated that the output torque profile of one phase energized is qualitatively equivalent to the BEMF profile for motors with reduced reluctance torque. It implies that design of BEMF profile is possible by magnetic modeling of a motor, without expensive and time-consuming experiments for different designs

  2. High Temperature Superconducting Magnets for Efficient Low Energy Beam Transport Systems

    CERN Document Server

    Popovic, M; Johnson, R P; Nipper, J H

    2013-01-01

    Modern ion accelerators and ion implantation systems need very short, highly versatile, Low Energy Beam Transport (LEBT) systems. The need for reliable and continuous operation requires LEBT designs to be simple and robust. The energy efficiency of available high temperature superconductors (HTS), with efficient and simple cryocooler refrigeration, is an additional attraction. Innovative, compact LEBT systems based on solenoids designed and built with high-temperature superconductor will be developed using computer models and prototyped. The parameters will be chosen to make this type of LEBT useful in a variety of ion accelerators, ion implantation systems, cancer therapy synchrotrons, and research accelerators, including the ORNL SNS. The benefits of solenoids made with HTS will be evaluated with analytical and numerical calculations for a two-solenoid configuration, as will be used in the SNS prototype LEBT that will replace the electrostatic one at SNS, and a single solenoid configuration, as was proposed...

  3. Influence of magnetic arc oscillation and current pulsing on microstructure and high temperature tensile strength of alloy 718 TIG weldments

    Energy Technology Data Exchange (ETDEWEB)

    Sivaprasad, K. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai (India); Ganesh Sundara Raman, S. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai (India)]. E-mail: ganesh@iitm.ac.in; Mastanaiah, P. [Defence Research and Development Laboratory, Hyderabad (India); Madhusudhan Reddy, G. [Defence Metallurgical Research Laboratory, Hyderabad (India)

    2006-07-25

    The aim of the present work is to study the effect of magnetic arc oscillation and current pulsing on the microstructure and high temperature tensile strength of alloy 718 tungsten inert gas weldments. The magnetic arc oscillation technique resulted in refined Laves phase with lesser interconnectivity. The full benefits of current pulsing in breaking the dendrites could not be realized in the present study due to relatively higher heat input used in the welding process. In the direct aged condition weldments prepared using magnetic arc oscillation technique exhibited higher tensile strength due to the presence of refined and lesser-interconnected Laves particles. In the solution treated and aged condition, magnetic arc oscillated weldments exhibited lower tensile strength compared with the weldments made without arc oscillation due to the presence of large amounts of finer {delta} needles.

  4. Analysis of Magnetism in High Nitrogen Austenitic Stainless Steel and Its Elimination by High Temperature Gas Nitriding

    Institute of Scientific and Technical Information of China (English)

    Peng Wan; Yibin Ren; Bingchun Zhang; Ke Yang

    2011-01-01

    Stable austenitic structure in medical stainless steels is basically required for surgical implantation. A weak magnetism was found in a high nitrogen nickel-free austenitic stainless steel for cardiovascular stent application. This magnetic behavior in high nitrogen stainless steel was investigated by optical microscopy, X-ray diffraction (XRD), electron probe microanalysis (EPMA) and superconducting quantum interference device (SQUID). The results showed that the magnetism came from the composition segregation of ferrite formation elements such as Cr and Mo in the steel and some δ-ferrites were locally formed during the pressurized electroslag remelting process. The magnetism of high nitrogen stainless steel could be eliminated by a proper high temperature gas nitriding (HTGN).

  5. Characteristic and magnetic field analysis of a high temperature superconductor axial-flux coreless induction maglev motor

    Science.gov (United States)

    Wei, Qin; Yu, Fan; Jin, Fang; Shuo, Li; Guoguo, Li; Gang, Lv

    2012-04-01

    A new high temperature superconductor axial-flux coreless maglev motor (HTS AFIM) is proposed, of which the primary windings are made of HTS tapes and the secondary is a non-magnetic conductor. The main works of this paper are the magnetic-field computation and characteristics analysis of HTS AFIM. For the first one, the reduction of magnetic fields near outer and inner radius of the HTS AFIM is solved by introducing the sub-loop electro-magnetic model along the radial position. For the second one, the AC losses of HTS coils are calculated. The relationships between the device's characteristics and device parameters are presented, and the results indicate that under certain frequency and current levitation device can output enough lift force. The conclusions are verified by finite element calculations.

  6. Characteristic and magnetic field analysis of a high temperature superconductor axial-flux coreless induction maglev motor.

    Science.gov (United States)

    Wei, Qin; Yu, Fan; Jin, Fang; Shuo, Li; Guoguo, Li; Gang, Lv

    2012-04-01

    A new high temperature superconductor axial-flux coreless maglev motor (HTS AFIM) is proposed, of which the primary windings are made of HTS tapes and the secondary is a non-magnetic conductor. The main works of this paper are the magnetic-field computation and characteristics analysis of HTS AFIM. For the first one, the reduction of magnetic fields near outer and inner radius of the HTS AFIM is solved by introducing the sub-loop electro-magnetic model along the radial position. For the second one, the AC losses of HTS coils are calculated. The relationships between the device's characteristics and device parameters are presented, and the results indicate that under certain frequency and current levitation device can output enough lift force. The conclusions are verified by finite element calculations.

  7. Self-suspended permanent magnetic FePt ferrofluids

    KAUST Repository

    Dallas, Panagiotis

    2013-10-01

    We present the synthesis and characterization of a new class of self-suspended ferrofluids that exhibit remanent magnetization at room temperature. Our system relies on the chemisorption of a thiol-terminated ionic liquid with very low melting point on the surface of L10 FePt nanoparticles. In contrast, all types of ferrofluids previously reported employ either volatile solvents as the suspending media or superparamagnetic iron oxide nanoparticles (that lacks permanent magnetization) as the inorganic component. The ferrofluids do not show any sign of flocculation or phase separation, despite the strong interactions between the magnetic nanoparticles due to the strong chemisorption of the ionic liquid as evidenced by Raman spectroscopy and thermal analysis. Composites with high FePt loading (40 and 70. wt%) exhibit a pseudo solid-like rheological behavior and high remanent magnetization values (10.1 and 12.8. emu/g respectively). At lower FePt loading (12. wt%) a liquid like behavior is observed and the remanent and saturation magnetization values are 3.5 and 6.2. emu/g, respectively. The magnetic and flow properties of the materials can be easily fine tuned by controlling the type and amount of FePt nanoparticles used. © 2013 Elsevier Inc.

  8. A Review of Permanent Magnet Stirring During Metal Solidification

    Science.gov (United States)

    Zeng, Jie; Chen, Weiqing; Yang, Yindong; Mclean, Alexander

    2017-08-01

    Rather than using conventional electromagnetic stirring (EMS) with three-phase alternating current, permanent magnet stirring (PMS), based on the use of sintered NdFeB material which has excellent magnetic characteristics, can be employed to generate a magnetic field for the stirring of liquid metal during solidification. Recent experience with steel casting indicates that PMS requires less than 20 pct of the total energy compared with EMS. Despite the excellent magnetic density properties and low power consumption, this relatively new technology has received comparatively little attention by the metal casting community. This paper reviews simulation modeling, experimental studies, and industrial trials of PMS conducted during recent years. With the development of magnetic simulation software, the magnetic field and associated flow patterns generated by PMS have been evaluated. Based on the results obtained from laboratory experiments, the effects of PMS on metal solidification structures and typical defects such as surface pinholes and center cavities are summarized. The significance of findings obtained from trials of PMS within the metals processing sector, including the continuous casting of steel, are discussed with the aim of providing an overview of the relevant parameters that are of importance for further development and industrial application of this innovative technology.

  9. Slip Torque Investigation and Magnetic Redesign of Motor Integrated Permanent Magnet Gear

    DEFF Research Database (Denmark)

    Frandsen, Tommy Vestergaard; Rasmussen, Peter Omand

    2015-01-01

    This paper presents an investigation of 20% difference between the measured and calculated slip torque of a Motor Integrated Permanent Magnet Gear (MIPMG) prototype. The High Speed (HS) side of the Magnetic Gear (MG) was fixed by loading the motor when conducting the slip torque measurement...

  10. Improving torque per kilogram magnet of permanent magnet couplings using finite element analysis

    DEFF Research Database (Denmark)

    Högberg, Stig; Jensen, Bogi Bech; Bendixen, Flemming Buus

    2013-01-01

    This paper presents the methodology and subsequent findings of a performance-improvement routine that employs automated finite element (FE) analysis to increase the torque-per-kilogram-magnet (TPKM) of a permanent magnet coupling (PMC). The routine is applied to a commercially available cylindrical...

  11. Microscopic observation of magnetic bacteria in the magnetic field of a rotating permanent magnet.

    Science.gov (United States)

    Smid, Pieter; Shcherbakov, Valeriy; Petersen, Nikolai

    2015-09-01

    Magnetotactic bacteria are ubiquitous and can be found in both freshwater and marine environments. Due to intracellular chains of magnetic single domain particles, they behave like swimming compass needles. In external magnetic fields like the Earth's magnetic field, a torque is acting on the chain. This will cause the bacterium to be rotated and aligned with the external field. The swimming direction of magnetotactic bacteria can be controlled with external magnetic fields, which makes it convenient to study them under a light microscope. Usually, a special set of coils arranged around a light microscope is used to control the swimming magnetotactic bacteria. Here, we present a simple mechanical system with a permanent magnet, which produces a rotating magnetic field of nearly constant amplitude in the focal plane of a light microscope. The device is placed beside the light microscope and easily adaptable to almost any microscope and thus convenient for field experiments. To describe the trajectories qualitatively, a theoretical model of the trajectories is presented. This device can be used to control the swimming direction of magnetotactic bacteria and also for studying their magnetic and hydrodynamic properties.

  12. Prediction and analysis of magnetic forces in permanent magnet brushless dc motor with rotor eccentricity

    Science.gov (United States)

    Liu, Z. J.; Li, J. T.; Jabbar, M. A.

    2006-04-01

    In design of permanent magnet motors for high-precision applications, it is sometimes necessary, early in the design stage, to have a detailed analysis of the effect of rotor eccentricity that may result from manufacturing imperfectness or use of fluid dynamic or aerodynamic bearings. This paper presents an analytical model for electromagnetic torque and forces in permanent magnet motors with rotor eccentricity. The model gives an insight to the relationship between the effect of the eccentricity and the other motor design parameters on the electromagnetic forces. It is shown that the calculated magnetic forces obtained from this model agree well with those obtained from numerical simulations that are very computationally demanding.

  13. Permanent Magnetic Synchronous Motor Control System Based on ADRC

    Directory of Open Access Journals (Sweden)

    Song Wang

    2013-06-01

    Full Text Available Permanent magnetic synchronous motor (PMSM is a strong coupling and non-linear system. In the PMSM speed-regulation system, PID controller is the conventional one, it is difficult to decide the parameters of PID. Moreover, the performance of PID controller is not very well in large disturbance. In the paper, the Active Disturbance Rejection Controller (ADRC is applied to the PMSM speed-regulation system. The result of simulations and experiments show that this algorithm has better anti-load-disturbance performance than PID controller.

  14. Axial Permanent Magnet Generator for Wearable Energy Harvesting

    DEFF Research Database (Denmark)

    Högberg, Stig; Sødahl, Jakob Wagner; Mijatovic, Nenad

    2016-01-01

    An increasing demand for battery-free electronics is evident by the rapid increase of wearable devices, and the design of wearable energy harvesters follows accordingly. An axial permanent magnet generator was designed to harvest energy from human body motion and supplying it to a wearable...... in order to reduce the rotor inertia and to reduce losses. Analytical models and finite element simulations were employed for the analyses of both generator types, and verified experimentally by prototypes. The results suggested that a generator of this size and power rating (20 mm radius, and 5 m...

  15. Modelling of Permanent Magnet Synchronous Motor Incorporating Core-loss

    Directory of Open Access Journals (Sweden)

    K. Suthamno

    2012-08-01

    Full Text Available This study proposes a dq-axis modelling of a Permanent Magnet Synchronous Motor (PMSM with copper-loss and core-loss taken into account. The proposed models can be applied to PMSM control and drive with loss minimization in simultaneous consideration. The study presents simulation results of direct drive of a PMSM under no-load and loaded conditions using the proposed models with MATLAB codes. Comparisons of the results are made among those obtained from using PSIM and SIMULINK software packages. The comparison results indicate very good agreement.

  16. A strong permanent magnet-assisted electromagnetic undulator

    Science.gov (United States)

    Halbach, K.

    1987-01-30

    This invention discloses an improved undulator comprising a plurality of electromagnet poles located along opposite sides of a particle beam axis with alternate north and south poles on each side of the beam to cause the beam to wiggle or undulate as it travels generally along the beam axis and permanent magnets spaced adjacent the electromagnetic poles on each side of the axis of said particle beam in an orientation sufficient to reduce the saturation of the electromagnet poles whereby the field strength of the electromagnet poles can be increased beyond the normal saturation levels of the electromagnetic poles. 4 figs.

  17. High-Temperature Superconductivity

    Science.gov (United States)

    Tanaka, Shoji

    2006-12-01

    A general review on high-temperature superconductivity was made. After prehistoric view and the process of discovery were stated, the special features of high-temperature superconductors were explained from the materials side and the physical properties side. The present status on applications of high-temperature superconductors were explained on superconducting tapes, electric power cables, magnets for maglev trains, electric motors, superconducting quantum interference device (SQUID) and single flux quantum (SFQ) devices and circuits.

  18. Study on the characteristics of magnetic levitation for permanent magnets and ferromagnetic materials with various sizes using stacked HTS bulk annuli

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.B., E-mail: kim@elec.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, 3-1-1, Tsushima-Naka, Kita-ku, Okayama 700-8530 (Japan); Matsunaga, J.; Doi, A.; Ikegami, T. [Graduate School of Natural Science and Technology, Okayama University, 3-1-1, Tsushima-Naka, Kita-ku, Okayama 700-8530 (Japan); Onodera, H. [JST-CREST, K’s Gobancho 6F, 7 Gobancho, Chiyoda-ku, Tokyo 102-0076 (Japan)

    2013-01-15

    Highlights: ► We achieved the stable levitation of irons by magnetized HTS bulk annuli. ► The relationship between magnetized field and sample size was cleared. ► The iron samples smaller than 1 mm diameter could not levitate stably. ► The spherical solenoid magnet was fabricated to levitate small iron samples. -- Abstract: We achieved stable levitation of cylindrical permanent magnets and irons using stacked ring-shaped high temperature superconducting (HTS) bulks with 20 mm ID, 60 mm OD and 50 mm height, and those were magnetized by field cooling method. The levitation characteristics of permanent magnets and iron samples located in the inner space of that levitation system were investigated experimentally. Iron samples with needle-shape and smaller than 1 mm diameter could not levitate stably. However, we found that the high strength of magnetized field was not necessary to levitate small needle-shaped irons. In order to levitate them, we need a uniform magnetic field in radial direction, so, a spherical solenoid magnet that can easily make a homogeneous magnetic field in inner space of HTS bulk annuli was developed. The spherical solenoid magnet, composed of seven solenoid coils with different inner and outer diameters, was designed by an electromagnetic analysis and fabricated.

  19. ANALYSIS OF THERMAL STATE OF TRACTION BRUSHLESS PERMANENT MAGNET MOTOR FOR MINE ELECTRIC LOCOMOTIVE

    Directory of Open Access Journals (Sweden)

    A. V. Matyuschenko

    2016-12-01

    Full Text Available Purpose. The study was conducted to analyze thermal state of the traction permanent magnet synchronous motor for mine electric battery locomotive when operating in continuous and short-time duty modes. These operating modes are selected for study, as they are typical for mine electric locomotives. Methodology. Thermal calculation was performed by means of FEM in three-dimensional formulation of problem using Jmag-Designer. Results. The modeling results of thermal state of the PMSM in continuous and short-time duty operation modes showed good agreement with experimental results. The results showed that the temperature of PM is higher than temperature of the stator winding in continuous operation mode. It was found that PM temperature might reach excessive values because of the high presence of eddy current losses in neodymium PM. Therefore, special attention in the design and testing of PMSM should be paid to the temperature of PM in various operation modes. Practical value. It was recommended to use high temperature permanent magnets in traction PMSM to avoid demagnetization of PM and performance degradation.

  20. Additive Manufacturing of Near-net Shaped Permanent Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Paranthaman, M Parans [ORNL

    2016-07-26

    The technical objective of this technical collaboration phase I proposal is to fabricate near net-shaped permanent magnets using alloy powders utilizing direct metal deposition technologies at the ORNL MDF. Direct Manufacturing using the POM laser system was used to consolidate Nd2Fe14B (NdFeB) magnet powders into near net-shape parts efficiently and with virtually no wasted material as part of the feasibility study. We fabricated builds based on spherical NdFeB magnet particles. The results show that despite the ability to fabricate highly reactive materials in the laser deposition process, the magnetic coercivity and remanence of the NdFeB hard magnets is significantly reduced. X-ray powder diffraction in conjunction with electron microscopy showed that the material experienced a primary Nd2Fe17Bx solidification due to the undercooling effect (>60K). Consequently the presence of alpha iron phase resulted in deterioration of the build properties. Further optimization of the processing parameters is needed to maintain the Nd2Fe14B phase during fabrication.

  1. Magnetization reversal processes of isotropic permanent magnets with various inter-grain exchange interactions

    Directory of Open Access Journals (Sweden)

    Hiroshi Tsukahara

    2017-05-01

    Full Text Available We performed a large-scale micromagnetics simulation on a supercomputing system to investigate the properties of isotropic nanocrystalline permanent magnets consisting of cubic grains. In the simulation, we solved the Landau–Lifshitz–Gilbert equation under a periodic boundary condition for accurate calculation of the magnetization dynamics inside the nanocrystalline isotropic magnet. We reduced the inter-grain exchange interaction perpendicular and parallel to the external field independently. Propagation of the magnetization reversal process is inhibited by reducing the inter-grain exchange interaction perpendicular to the external field, and the coercivity is enhanced by this restraint. In contrast, when we reduce the inter-grain exchange interaction parallel to the external field, the coercivity decreases because the magnetization reversal process propagates owing to dipole interaction. These behaviors show that the coercivity of an isotropic permanent magnet depends on the direction of the inter-grain exchange interaction.

  2. Improved Electrical Insulation of Rare Earth Permanent Magnetic Materials With High Magnetic Properties

    Institute of Scientific and Technical Information of China (English)

    CHANG Ying; WANG Da-peng; LI Wei; PAN Wei; YU Xiao-jun; QI Min

    2009-01-01

    Rare earth permanent magnetic materials are typical electrical conductor, and their magnetic properties will decrease because of the eddy current effect, so it is difficult to keep them stable for a long enough time under a high frequency AC field. In the present study, as far as rare earth permanent magnets are concerned, for the first time, rare earth permanent magnets with strong electrical insulation and high magnetic performance have been obtained through experiments, and their properties are as follows:(1) Sm2TM17: Br=0.62 T, jHc=803.7 kA/m, (BH)m= The magnetic properties of Sm2TM17 and NdFeB are obviously higher than those of ferrite permanent magnet, and the electric insulating characteristics of Sm2TM17 and NdFeB applied have in fact been approximately the same as those of ferrite. Therefore, Sm2TM17 and NdFeB will possess the ability to take the place of ferrite under a certain high frequency AC electric field.

  3. A compact permanent magnet cyclotrino for accelerator mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Young, A.T.; Clark, D.J.; Kunkel, W.B.; Leung, K.N.; Li, C.Y. [Lawrence Berkeley Lab., CA (United States)

    1995-02-01

    The authors describe the development of a new instrument for the detection of trace amounts of rare isotopes, a Cyclotron Mass Spectrometer (CMS). A compact low energy cyclotron optimized for high mass resolution has been designed and has been fabricated. The instrument has high sensitivity and is designed to measure carbon-14 at abundances of < 10{sup {minus}12}. A novel feature of the instrument is the use of permanent magnets to energize the iron poles of the cyclotron. The instrument uses axial injection, employing a spiral inflector. The instrument has been assembled and preliminary measurements of the magnetic field show that it has a uniformity on the order of 2 parts in 10{sup 4}.

  4. Plasma Diagnostic and Performance of a Permanent Magnet Hall Thruster

    CERN Document Server

    Ferreira, J L; Rego, I D S; Ferreira, I S; Ferreira, Jose Leonardo; Souza, Joao Henrique Campos De; Rego, Israel Da Silveira; Ferreira, Ivan Soares

    2004-01-01

    Electric propulsion is now a sucessfull method for primary propulsion of deep space long duration missions and for geosyncronous satellite attitude control. Closed Drift Plasma Thruster, so called Hall Thruster or SPT (stationary plasma thruster) were primarily conceived in USSR (the ancient Soviet Union) and now it is been developed by space agencies, space research institutes and industries in several countries such as France, USA, Israel, Russian Federation and Brazil. In this work, we show plasma characteristics and performance of a Hall Thruster designed with an innovative concept which uses an array of permanent magnets, instead of an eletromagnet, to produce a radial magnetic field inside its cylindrical plasma drift channel. Within this new concept, we expect to develop a Hall Thruster within power consuption that will scale up to small and medium size satellites. A plasma density and temperature space profiles inside and outside the thruster channel will be shown. Space plasma potential, ion temperat...

  5. Torque analysis for double-stator permanent-magnet motor

    Institute of Scientific and Technical Information of China (English)

    柴凤; 程树康; 崔淑梅

    2002-01-01

    In addition to the characteristics of a conventional motor, a novel direct-drive double-stator perma-nent-magnet brushless motor proposed can operate in the state of either a generator or a motor as appropriate.Through numerical calculation and analysis, the output torque of double-stator permanent-magnet brushless motor of the same volume as the traditional machine is discussed, and the reduction of torque ripple by using the structure features of this motor is investigated. The results indicate that lower torque ripple under the condition of ideal effective torque can be obtained by the rational design of motor. The prototype motors tested show that this kind of motor structure has a higher power density.

  6. An improved iron loss estimation for permanent magnet brushless machines

    CERN Document Server

    Fang, D

    1999-01-01

    This paper presents an improved approach for predicting iron losses in permanent magnet brushless machines. The new approach is based on the fundamental concept that eddy current losses are proportional to the square of the time rate of change of flux density. Expressions are derived for predicting hysteresis and eddy current losses in the stator teeth and yoke. The so-called anomalous or excess losses, caused by the induced eddy current concentration around moving magnetic domain walls and neglected in the conventional core loss calculation, are also included in the proposed approach. In addition, the model is also capable of accounting for the stator skewing, if present. The core losses obtained from the proposed approach are compared with those measured on an existing PM motor at several operating speeds, showing very good agreement. (14 refs).

  7. Double-layer rotor magnetic shield performance analysis in high temperature superconducting synchronous generators under short circuit fault conditions

    Science.gov (United States)

    Hekmati, Arsalan; Aliahmadi, Mehdi

    2016-12-01

    High temperature superconducting, HTS, synchronous machines benefit from a rotor magnetic shield in order to protect superconducting coils against asynchronous magnetic fields. This magnetic shield, however, suffers from exerted Lorentz forces generated in light of induced eddy currents during transient conditions, e.g. stator windings short-circuit fault. In addition, to the exerted electromagnetic forces, eddy current losses and the associated effects on the cryogenic system are the other consequences of shielding HTS coils. This study aims at investigating the Rotor Magnetic Shield, RMS, performance in HTS synchronous generators under stator winding short-circuit fault conditions. The induced eddy currents in different circumferential positions of the rotor magnetic shield along with associated Joule heating losses would be studied using 2-D time-stepping Finite Element Analysis, FEA. The investigation of Lorentz forces exerted on the magnetic shield during transient conditions has also been performed in this paper. The obtained results show that double line-to-ground fault is of the most importance among different types of short-circuit faults. It was revealed that when it comes to the design of the rotor magnetic shields, in addition to the eddy current distribution and the associated ohmic losses, two phase-to-ground fault should be taken into account since the produced electromagnetic forces in the time of fault conditions are more severe during double line-to-ground fault.

  8. Effect of the repulsive force in the HTSC-permanent magnet hybrid bearing system

    Energy Technology Data Exchange (ETDEWEB)

    Ohashi, S., E-mail: ohashi@ipcku.kansai-u.ac.j [Kansai University, 3-3-35, Yamate-cho, Suita, Osaka 564-8680 (Japan); Kobayashi, S. [Kansai University, 3-3-35, Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2009-10-15

    Magnetic levitation using the pinning force of the YBaCuO high-T{sub c} bulk superconductor (HTSC) materials has an advantage to achieve stable levitation without control. To increase levitation force, the HTSC-permanent magnet hybrid magnetic bearing system is introduced. A circular shaped three phase Nd-Fe-B permanent magnet is installed on the rotor, and HTSC bulk superconductor is set on the stator. The additional permanent magnet is installed under the HTSC. Repulsive force of the permanent magnet is used for levitation, and pinning force between the HTSC and permanent magnet is used for guidance force of the bearing. In this system, relationship between permanent magnet and the HTSC is important. When repulsive force of the permanent magnet is large, pinning force of superconductor is used to keep the rotor position. As a result, stability for the lateral direction is decreased with hybrid system. For levitation force, effect of the hybrid system is not observed with column HTSC. Compared with the ring HTSC results, the following thing is considered. Because there is no space that flux of one permanent magnet acts on the other one with the column HTSC configuration, interaction between two permanent magnets becomes small.

  9. Effect of the repulsive force in the HTSC-permanent magnet hybrid bearing system

    Science.gov (United States)

    Ohashi, S.; Kobayashi, S.

    2009-10-01

    Magnetic levitation using the pinning force of the YBaCuO high- Tc bulk superconductor (HTSC) materials has an advantage to achieve stable levitation without control. To increase levitation force, the HTSC-permanent magnet hybrid magnetic bearing system is introduced. A circular shaped three phase Nd-Fe-B permanent magnet is installed on the rotor, and HTSC bulk superconductor is set on the stator. The additional permanent magnet is installed under the HTSC. Repulsive force of the permanent magnet is used for levitation, and pinning force between the HTSC and permanent magnet is used for guidance force of the bearing. In this system, relationship between permanent magnet and the HTSC is important. When repulsive force of the permanent magnet is large, pinning force of superconductor is used to keep the rotor position. As a result, stability for the lateral direction is decreased with hybrid system. For levitation force, effect of the hybrid system is not observed with column HTSC. Compared with the ring HTSC results, the following thing is considered. Because there is no space that flux of one permanent magnet acts on the other one with the column HTSC configuration, interaction between two permanent magnets becomes small.

  10. Synthesis of high magnetization Fe and FeCo nanoparticles by high temperature chemical reduction

    Energy Technology Data Exchange (ETDEWEB)

    Kandapallil, B; Colborn, RE; Bonitatibus, PJ; Johnson, F

    2015-03-15

    Fe and FeCo ferromagnetic nanoparticles in the 5-10 nm size regimes featuring high magnetization were synthesized using a modified chemical reduction method. The structure and morphology of these nanoparticles were confirmed by XRD and TOM analysis. These small, monodisperse and phase pure nanoparticles exhibited magnetic saturation of 210 emu/g (Fe) and 220 emu/g (Fe+Co) for Fe and FeCo nanoparticles respectively. The magnetization was found to be dependent on the temperature at which the reducing agent was introduced. (C) 2014 Elsevier B.V. All rights reserved,

  11. Results of using permanent magnets to suppress Josephson noise in the KAPPa SIS receiver

    Science.gov (United States)

    Wheeler, Caleb H.; Neric, Marko; Groppi, Christopher E.; Underhill, Matthew; Mani, Hamdi; Weinreb, Sander; Russell, Damon S.; Kooi, Jacob W.; Lichtenberger, Arthur W.; Walker, Christopher K.; Kulesa, Craig

    2016-07-01

    We present the results from the magnetic field generation within the Kilopixel Array Pathfinder Project (KAPPa) instrument. The KAPPa instrument is a terahertz heterodyne receiver using a Superconducting-Insulating- Superconducting (SIS) mixers. To improve performance, SIS mixers require a magnetic field to suppress Josephson noise. The KAPPa test receiver can house a tunable electromagnet used to optimize the applied magnetic field. The receiver is also capable of accommodating a permanent magnet that applies a fixed field. Our permanent magnet design uses off-the-shelf neodymium permanent magnets and then reshapes the magnetic field using machined steel concentrators. These concentrators allow the use of an unmachined permanent magnet in the back of the detector block while two small posts provide the required magnetic field across the SIS junction in the detector cavity. The KAPPa test receiver is uniquely suited to compare the permanent magnet and electromagnet receiver performance. The current work includes our design of a `U' shaped permanent magnet, the testing and calibration procedure for the permanent magnet, and the overall results of the performance comparison between the electromagnet and the permanent magnet counterpart.

  12. Analysis and design of permanent magnet biased magnetic bearing based on hybrid factor

    Directory of Open Access Journals (Sweden)

    Jinji Sun

    2016-03-01

    Full Text Available In this article, hybrid factor is proposed for hybrid magnetic bearing. The hybrid factor is defined as the ratio of the force produced by the permanent magnet and the forces produced by the permanent magnet and current in hybrid magnetic bearing. It is deduced from a certain radial hybrid magnetic bearing using its important parameters such as the current stiffness and displacement stiffness at first and then the dynamic model of magnetically suspended rotor system is established. The relationship between structural parameters and control system parameters is analyzed based on the hybrid factor. Some influencing factors of hybrid factor in hybrid magnetic bearing, such as the size of the permanent magnet, length of air gap, and area of the stator poles, are analyzed in this article. It can be concluded that larger hybrid factor can be caused by the smaller power loss according to the definition of hybrid factor mentioned above. Meanwhile, the hybrid factor has a maximum value, which is related to control system parameters such as proportional factor expect for structural parameters. Finally, the design steps of parameters of hybrid magnetic bearing can be concluded.

  13. High Temperature Superconducting Maglev Measurement System

    OpenAIRE

    Wang, Jia-Su; Wang, Su-Yu

    2010-01-01

    Three high temperature superconducting (HTS) Maglev measurement systems were successfully developed in the Applied Superconductivity Laboratory (ASCLab) of Southwest Jiaotong University, P. R. China. These systems include liquid nitrogen vessel, Permanent Magnet Guideway (PMG), data collection and processing, mechanical drive and Autocontrol features. This chapter described the three different measuring systems along with their theory of operations and workflow. The SCML-01 HTS Maglev measure...

  14. Analysis and Design Optimization of a Coaxial Surface-Mounted Permanent-Magnet Magnetic Gear

    DEFF Research Database (Denmark)

    Zhang, Xiaoxu; Liu, Xiao; Wang, Chao

    2014-01-01

    This paper presents the analysis and design optimization of a coaxial surface-mounted permanent-magnet magnetic gear. The magnetic field distribution in the coaxial magnetic gear is calculated analytically in the polar coordinate system and then validated by the finite element method (FEM......) algorithm is employed to optimize the studied magnetic gear. Given that the torque capability and material cost conflict with each other, both of them are set as the optimization objectives in this paper. Different weight factors may be chosen for the two objectives so that more attention can be placed...

  15. Covalent magnetism, exchange interactions and anisotropy of the high temperature layered antiferromagnet MnB₂.

    Science.gov (United States)

    Khmelevskyi, S; Mohn, P

    2012-01-11

    The investigation of the electronic structure and magnetism for the compound MnB(2) with crystal structure type AlB(2) has been revisited to resolve contradictions between various experimental and theoretical results present in the literature. We find that MnB(2) exhibits an interesting example of a Kübler's covalent magnetism (Williams et al 1981 J. Appl. Phys. 52 2069). The covalent magnetism also appears to be the source of some disagreement between the calculated values of the magnetic moments and those given by neutron diffraction experiments. We show that this shortcoming is due to the atomic sphere approximation applied in earlier calculations. The application of the disordered local moment approach and the calculation of the inter-atomic exchange interactions within the Liechtenstein formalism reveal strong local moment antiferromagnetism with a high Néel temperature predicted from Monte Carlo simulations. A fully relativistic band structure calculation and then the application of the torque method yields a strong in-plane anisotropy of the Mn magnetic moments. The agreement of these results with neutron diffraction studies rules out any possible weak itinerant electron magnetism scenarios as proposed earlier for MnB(2).

  16. Characteristics Analysis of Square Wave BLDC Motor Considering Magnetization Distribution of Permanent Magnet

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Byung Il; Park, Seung Chan [Hanyang University (Korea, Republic of); Im, Tae Bin [Korea Electronics Technology Institute (Korea, Republic of); Kang, Young Gyu [Samsung Electro-Mechanics R and D Center (Korea, Republic of)

    1998-04-01

    This paper deals with the characteristics analysis of a permanent magnet brushless DC(BLDC) motor. The analysis method is to utilize the time-stepped finite element method considering the square wave voltage of MOS FET inverter. The system matrix that unknown parameters are magnetic vector potentials at nodes and phases currents is constructed through the finite element formulation and circuit equations, and then solved by bi-conjugate gradient(BCG) method. The analyzed model has a inner rotor which is consisted of a permanent magnet of ring shape and a laminated steel core. The current carrying free-wheeling diode of inverter is neglected because of low value of the winding inductance of motor. The magnetization distribution in the permanent magnet i determined by solving inverse problem that the calculated flux densities values on the surface of the permanent magnet are led to the same values that measured by gauss meter. And then, torque and phase currents, which are calculated by finite element analysis are compared with experimental values. (author). 12 refs., 17 figs., 2 tabs.

  17. Characterization of a high-temperature superconducting conductor on round core cables in magnetic fields up to 20 T

    Energy Technology Data Exchange (ETDEWEB)

    van der Laan, D. C.; Noyes, P. D.; Miller, G. E.; Weijers, H. W.; Willering, G. P.

    2013-02-13

    The next generation of high-ï¬eld magnets that will operate at magnetic ï¬elds substantially above 20 T, or at temperatures substantially above 4.2 K, requires high-temperature superconductors (HTS). Conductor on round core (CORC) cables, in which RE-Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} (RE = rare earth) (REBCO) coated conductors are wound in a helical fashion on a flexible core, are a practical and versatile HTS cable option for low-inductance, high-field magnets. We performed the first tests of CORC magnet cables in liquid helium in magnetic fields of up to 20 T. A record critical current I{sub c} of 5021 A was measured at 4.2 K and 19 T. In a cable with an outer diameter of 7.5 mm, this value corresponds to an engineering current density J{sub e} of 114 A mm{sup -2} , the highest J{sub e} ever reported for a superconducting cable at such high magnetic fields. Additionally, the first magnet wound from an HTS cable was constructed from a 6 m-long CORC cable. The 12-turn, double-layer magnet had an inner diameter of 9 cm and was tested in a magnetic field of 20 T, at which it had an I{sub c} of 1966 A. The cables were quenched repetitively without degradation during the measurements, demonstrating the feasibility of HTS CORC cables for use in high-field magnet applications.

  18. Characterization of a high-temperature superconducting conductor on round core cables in magnetic fields up to 20 T

    Energy Technology Data Exchange (ETDEWEB)

    van der Laan, D. C.; Noyes, P. D.; Miller, G. E.; Weijers, H. W.; Willering, G. P.

    2013-02-13

    The next generation of high-ï¬eld magnets that will operate at magnetic ï¬elds substantially above 20 T, or at temperatures substantially above 4.2 K, requires high-temperature superconductors (HTS). Conductor on round core (CORC) cables, in which RE-Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} (RE = rare earth) (REBCO) coated conductors are wound in a helical fashion on a flexible core, are a practical and versatile HTS cable option for low-inductance, high-field magnets. We performed the first tests of CORC magnet cables in liquid helium in magnetic fields of up to 20 T. A record critical current I{sub c} of 5021 A was measured at 4.2 K and 19 T. In a cable with an outer diameter of 7.5 mm, this value corresponds to an engineering current density J{sub e} of 114 A mm{sup -2} , the highest J{sub e} ever reported for a superconducting cable at such high magnetic fields. Additionally, the first magnet wound from an HTS cable was constructed from a 6 m-long CORC cable. The 12-turn, double-layer magnet had an inner diameter of 9 cm and was tested in a magnetic field of 20 T, at which it had an I{sub c} of 1966 A. The cables were quenched repetitively without degradation during the measurements, demonstrating the feasibility of HTS CORC cables for use in high-field magnet applications.

  19. Superconducting Solenoid and Press for Permanent Magnet Fabrication

    Science.gov (United States)

    Mulcahy, T. M.; Hull, J. R.

    2002-08-01

    For the first time, a superconducting solenoid (SCM) was used to increase the remnant magnetization of sintered NdFeB permanent magnets (PMs). In particular, improved magnetic alignment of commercial-grade PM powder was achieved, as it was axial die pressed into 12.7-mm diameter cylindrical compacts in the 76.2-mm warm bore of a 9-T SCM. The press used to compact the powder is unique and was specifically designed for use with the SCM. Although the press was operated in the batch mode for this proof of concept study, its design is intended to enable automated production. In operation, a simple die and punch set made of nonmagnetic materials was filled with powder and loaded into a nonmagnetic press tube. The cantilevered press tube was inserted horizontally, on a carrier manually advanced along a track, into the SCM. The robustness of the mechanical components and the SCM, in its liquid helium dewar, were specifically designed to allow for insertion and extraction of the magnetic powder and compacts, while operating at 9 T.

  20. Design considerations for permanent magnet direct drive generators for wind energy applications

    NARCIS (Netherlands)

    Jassal, A.K.; Polinder, H.; Damen, M.E.C.; Versteegh, K.

    2012-01-01

    Permanent Magnet Direct Drive (PMDD) generators offer very high force density, high efficiency and low number of components. Due to these advantages, PMDD generators are getting popular in the wind energy industry especially for offshore application. Presence of permanent magnets gives magnetic fiel

  1. Design considerations for permanent magnet direct drive generators for wind energy applications

    NARCIS (Netherlands)

    Jassal, A.K.; Polinder, H.; Damen, M.E.C.; Versteegh, K.

    2012-01-01

    Permanent Magnet Direct Drive (PMDD) generators offer very high force density, high efficiency and low number of components. Due to these advantages, PMDD generators are getting popular in the wind energy industry especially for offshore application. Presence of permanent magnets gives magnetic

  2. Field cooling of a MgB{sub 2} cylinder around a permanent magnet stack: prototype for superconductive magnetic bearing

    Energy Technology Data Exchange (ETDEWEB)

    Perini, E; Giunchi, G [EDISON S.p.A., R and D Division, Foro Buonaparte 31, 20121 Milano (Italy)], E-mail: elena.perini@edison.it, E-mail: giovanni.giunchi@edison.it

    2009-04-15

    The behaviour of bulk superconductors as levitators of permanent magnets (PMs) has been extensively studied for the textured YBCO high-temperature superconductor material, in the temperature range lower than 77 K, obtaining extremely high trapped fields but also experiencing limitations on the mechanical characteristics of the material and on the possibility to produce large objects. Alternatively, bulk MgB{sub 2}, even if it is superconducting at lower temperatures, has fewer mechanical problems, when fully densified, and presents stable magnetization in the temperature range between 10 and 30 K. With the reactive Mg-liquid infiltration technique we have produced dense MgB{sub 2} bulk cylinders of up to 65 mm diameter and 100 mm height. This kind of cylinder can be consider as a prototype of a passive magnetic bearing for flywheels or other rotating electrical machines. We have conductively cooled one of these superconducting cylinders inside a specially constructed cryostat, and the levitation forces and stiffness, with respect to axial movements of various arrangements of the PM, have been measured as a function of the temperature below T{sub c}. We verified the very stable characteristics of the induced magnetization after several cycles of relative movements of the PM and the superconducting cylinder.

  3. Field cooling of a MgB2 cylinder around a permanent magnet stack: prototype for superconductive magnetic bearing

    Science.gov (United States)

    Perini, E.; Giunchi, G.

    2009-04-01

    The behaviour of bulk superconductors as levitators of permanent magnets (PMs) has been extensively studied for the textured YBCO high-temperature superconductor material, in the temperature range lower than 77 K, obtaining extremely high trapped fields but also experiencing limitations on the mechanical characteristics of the material and on the possibility to produce large objects. Alternatively, bulk MgB2, even if it is superconducting at lower temperatures, has fewer mechanical problems, when fully densified, and presents stable magnetization in the temperature range between 10 and 30 K. With the reactive Mg-liquid infiltration technique we have produced dense MgB2 bulk cylinders of up to 65 mm diameter and 100 mm height. This kind of cylinder can be consider as a prototype of a passive magnetic bearing for flywheels or other rotating electrical machines. We have conductively cooled one of these superconducting cylinders inside a specially constructed cryostat, and the levitation forces and stiffness, with respect to axial movements of various arrangements of the PM, have been measured as a function of the temperature below Tc. We verified the very stable characteristics of the induced magnetization after several cycles of relative movements of the PM and the superconducting cylinder.

  4. Demonstration, Testing and Qualification of a High Temperature, High Speed Magnetic Thrust Bearing

    Science.gov (United States)

    DeWitt, Kenneth

    2005-01-01

    The gas turbine industry has a continued interest in improving engine performance and reducing net operating and maintenance costs. These goals are being realized because of advancements in aeroelasticity, materials, and computational tools such as CFD and engine simulations. These advancements aid in increasing engine thrust-to-weight ratios, specific fuel consumption, pressure ratios, and overall reliability through higher speed, higher temperature, and more efficient engine operation. Currently, rolling element bearing and squeeze film dampers are used to support rotors in gas turbine engines. Present ball bearing configurations are limited in speed (bearings require extensive preventative maintenance in order to assure their safe operation. Since these bearings are at their operational limits, new technologies must be found in order to take advantage of other advances. Magnetic bearings are well suited to operate at extreme temperatures and higher rotational speeds and are a promising solution to the problems that conventional rolling element bearings present. Magnetic bearing technology is being developed worldwide and is considered an enabling technology for new engine designs. Using magnetic bearings, turbine and compressor spools can be radically redesigned to be significantly larger and stiffer with better damping and higher rotational speeds. These advances, a direct result of magnetic bearing technology, will allow significant increases in engine power and efficiency. Also, magnetic bearings allow for real-time, in-situ health monitoring of the system, lower maintenance costs and down time.

  5. Rotational characteristics in the resonance state of the HTSC-permanent magnet hybrid magnetic bearing

    Energy Technology Data Exchange (ETDEWEB)

    Morii, Y.; Sukedai, M. [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan); Ohashi, S., E-mail: ohashi@kansai-u.ac.jp [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2011-11-15

    The hybrid magnetic bearing has been developed. In the hybrid system, effect of the pinning force becomes smaller. Influence of the vibration and the gradient angle in the resonance state is large. The resonance frequency becomes small in the hybrid bearing system. The hybrid magnetic bearing using permanent magnets and the high-Tc bulk superconductor (HTSC) has been developed. Repulsive force of the permanent magnet is introduced to increase the load weight of the magnetic bearing. Effect of the hybrid system has been shown. In this paper, influence of the hybrid system on the dynamic characteristics of the rotor is studied. The rotational characteristics in the mechanical resonance state are studied, and the equivalent magnetic spring coefficient is estimated from the experimental results of the load weight. The resonance frequency is measured by the rotation experiments. The rotor achieves stable levitation even in the resonance state. In the hybrid system, effect of the pinning force becomes smaller than that of the lateral force generated by the repulsive force between the two permanent magnets at the smaller air gap. Thus influence of the lateral vibration and the gradient angle in the resonance state becomes larger at a smaller air gap. The equivalent magnetic spring coefficient becomes also small, and the resonance frequency becomes small in the hybrid bearing system.

  6. Motor Integrated Permanent Magnet Gear with a Wide Torque-Speed Range

    DEFF Research Database (Denmark)

    Rasmussen, Peter Omand; Matzen, Torben N.; Jahns, T. M.

    2009-01-01

    This paper present a new motor integrated permanent magnet gear with a wide torque-speed range. In the paper a 35 kW permanent magnet motor with a base speed of 4000 rpm and a top speed of 14000 rpm is integrated into a permanent magnetic gear with a gearing ratio of 8.67. The design process of t...... may be useful as a direct drive wheel motor for EV's and no liquid cooling system is required....

  7. Cryostabilization of high-temperature superconducting magnets with subcooled flow in microchannels

    Science.gov (United States)

    Cha, Y. S.; Hull, J. R.; Choi, U. S.

    1992-07-01

    Subcooled flow of liquid nitrogen in microchannels is proposed as a means to enhance the stability of a superconducting magnet. Analysis shows high current density or a low stabilizer fraction is obtainable in a cryostable magnet. Increase in stability (using the Stekley criterion) is directly related to coolant velocity and coolant channel aspect ratio, however, there is a corresponding increase in pressure drop of the system. Another constraint is the coolant temperature rise, which is found to be a function of coolant residence time and the coolant to conductor ratio.

  8. High temperature magnetic properties of nanocrystalline Sn0.95Co0.05O2

    Indian Academy of Sciences (India)

    O Mounkachi; E Salmani; M Boujnah; H Labrim; H El Moussaoui; M Hamedoun; A Benyoussef; A El Kenz; H Ez-Zahraouy; R Masrour; E K Hlil

    2014-05-01

    Structural and magnetic properties of Sn0.95Co0.05O2 nanocrystalline and diluted magnetic semiconductors have been investigated. This sample has been synthesized by co-precipitation route. Study of magnetization hysteresis loop measurements infer that the sample of Sn0.95Co0.05O2 nanoparticle shows a well-defined hysteresis loop at 300 K temperature, which reflects its ferromagnetic behaviour. We confirmed the room-temperature intrinsic ferromagnetic (FM) semiconductors by ab initio calculation, using the theory of the functional of density (DFT) by employing the method of Korringa–Kohn–Rostoker (KKR) as well as coherent potential approximation (CPA, explain the disorder effect) to systems. The ferromagnetic state energy was calculated and compared with the local-moment-disordered (LMD) state energy for local density approximation (LDA) and LDA–SIC approximation. Mechanism of hybridization and interaction between magnetic ions in Sn0.95Co0.05O2 is also investigated. To explain the origin of ferromagnetic behaviour, we give information about total and atoms projected density of state functions.

  9. Protection of a test magnet wound with a Ag/BSCCO high-temperature superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Dresner, L.

    1992-10-01

    The properties of Ag/BSCCO conductor are studied and used to evaluate the feasibility of detecting normal zones in the conductor before the hot-spot temperature reaches critical levels. The results are applied to the protection of a 5-kJ test magnet.

  10. Influence of magnetic field on the turbulence of plane high temperature gas flow

    Energy Technology Data Exchange (ETDEWEB)

    Levitan, Yu.S.

    1977-01-01

    Expressions are obtained within the framework of the Prandtl hypothesis and proposition on local-isotropic turbulence for turbulent friction and thermal flow in a channel flow of an electrical-conducting medium with a current along the channel's axis in the internal magnetic field, and which account for temperature fluctuations of the medium. 6 references.

  11. Stresses evolution at high temperature (200°C on the interface of thin films in magnetic components

    Directory of Open Access Journals (Sweden)

    Doumit Nicole

    2014-07-01

    Full Text Available In the field of electronics, the increase of operating temperatures is a major industrial and scientific challenge because it allows reducing mass and volume of components especially in the aeronautic domain. So minimizing our components reduce masses and the use of cooling systems. For that, the behaviours and interface stresses of our components (in particular magnetic inductors and transformers that are constituted of one magnetic layer (YIG or an alumina substrate (Al2O3 representing the substrate and a thin copper film are studied at high temperature (200°C. COMSOL Multiphysics is used to simulate our work and to validate our measurements results. In this paper, we will present stresses results according to the geometrical copper parameters necessary for the component fabrication. Results show that stresses increase with temperature and copper’s thickness while remaining always lower than 200MPa which is the rupture stress value.

  12. One-loop omega-potential of charged massive fields in a constant homogeneous magnetic field at high temperatures

    CERN Document Server

    Kalinichenko, I S

    2016-01-01

    The explicit expressions for the high-temperature expansions of the one-loop corrections to the omega-potential coming from the charged scalar and Dirac particles and, separately, from antiparticles in a constant homogeneous magnetic field are derived. The explicit expressions for the non-perturbative corrections to the effective action at finite temperature and density are obtained. The thermodynamic properties of a gas of charged scalars in a constant homogeneous magnetic field are analyzed in the one-loop approximation. It turns out that, in this approximation, the system suffers the first order phase transition from the diamagnetic to the superconducting state at sufficiently high densities. The improvement of the one-loop result by summing the ring diagrams is investigated. This improvement leads to a drastic change of the thermodynamic properties of the system. The gas of charged scalars passes to the ferromagnetic state in place of the superconducting one at high densities and sufficiently low temperat...

  13. A simple, small and low cost permanent magnet design to produce homogeneous magnetic fields.

    Science.gov (United States)

    Manz, B; Benecke, M; Volke, F

    2008-05-01

    A new portable, pocket-size NMR probe based on a novel permanent magnet arrangement is presented. It is based on a Halbach-type magnet design which mimics the field of a spherical dipole by using cylindrical bar and ring magnets. The magnet system is made up of only three individual magnets, and most field calculations and optimisations can be performed analytically. A prototype system has been built using a set of small, off the shelf commercially available permanent magnets. Proton linewidths of 50 ppm FWHM could be achieved at a field strength of 1T. Calculations show that with custom-sized permanent magnets, linewidths of less than 1 ppm can be achieved over sample volumes of up to 1 mm3, which would in theory enable chemical shift resolved proton spectroscopy on mass-limited samples. But even with the achieved linewidth of 50 ppm, this can be a useful portable sensor for small amounts of liquid samples with restricted molecular mobility, like gels, polymers or high viscosity liquids.

  14. Rotational characteristics in the resonance state of the HTSC-permanent magnet hybrid magnetic bearing

    Science.gov (United States)

    Morii, Y.; Sukedai, M.; Ohashi, S.

    2011-11-01

    The hybrid magnetic bearing using permanent magnets and the high-Tc bulk superconductor (HTSC) has been developed. Repulsive force of the permanent magnet is introduced to increase the load weight of the magnetic bearing. Effect of the hybrid system has been shown. In this paper, influence of the hybrid system on the dynamic characteristics of the rotor is studied. The rotational characteristics in the mechanical resonance state are studied, and the equivalent magnetic spring coefficient is estimated from the experimental results of the load weight. The resonance frequency is measured by the rotation experiments. The rotor achieves stable levitation even in the resonance state. In the hybrid system, effect of the pinning force becomes smaller than that of the lateral force generated by the repulsive force between the two permanent magnets at the smaller air gap. Thus influence of the lateral vibration and the gradient angle in the resonance state becomes larger at a smaller air gap. The equivalent magnetic spring coefficient becomes also small, and the resonance frequency becomes small in the hybrid bearing system.

  15. Basic Characteristics of the Propulsion System in the Permanent Magnet-HTSC Hybrid Magnetic Conveyance System

    Science.gov (United States)

    Ohashi, Shunsuke; Kumano, Daiki; Goto, Yasuyuki

    The Hybrid magnetically levitated transportation system has been developed. The magnetic rail is set on the ground, and the carrier with permanent magnets and high-Tc superconductors (HTSC) levitates on the rail. Repulsive force of permanent magnet is introduced to support load weight. Pinning force of the HTSC is used to support weight of the frame of the carrier and to achieve lateral stability of the carrier. In this paper, propulsion system of the conveyance system is studied. Propulsion function is installed on the carrier body. Magnetic gradient is used to get propulsion force. Propulsion force of the system is little. So propulsion rail system is introduced. Air core copper coils are installed on the magnetic rail. Interaction between current of these coils and permanent magnets on the carrier generates propulsion force. Enough propulsion force is given. Influence of the propulsion system on the levitation and guidance system is measured. Stability of levitation and guidance system is enough even when propulsion system is operated.

  16. Novel design configurations for permanent magnet wind generators

    Science.gov (United States)

    Chen, Yicheng

    2004-12-01

    The aim of this research is to search for optimal designs of permanent magnet (PM) wind generators of different topologies. The dissertation deals with the development of analytical design equations and formulas for PM wind generators of different topologies, including equivalent magnetic circuit model for magnets, calculation of leakage flux, influence of d-q axis armature reaction, flux waveform analysis, as well as performance verification. 3-D and simplified 2-D finite element analysis is used to enhance the design precision, by which analytical formulas are modified. A new and improved formula is proposed for lamination loss calculations, based on a large experimental data set provided by steel manufacturers. The temperature stability of NdFeB magnets is analyzed and some proposals for eliminating irreversible demagnetization are presented. Two existing experimental machines are used to validate the design equations. The genetic algorithms are used to investigate the multi-objective design optimization of PM wind generators for a high efficiency and light-weight design. The reasoning behind the selection of the objective functions, design variables and constraints are given as guidance for the PM wind generator optimum design. The implementation of the genetic algorithm is also given. A comparison of PM wind generators of different topologies is presented. Conclusions are drawn for topology selections of PM wind generators. The group of soft magnetic composites (SMC) has recently been expanded by the introduction of new materials with significantly improved frequency properties. This has made SMC a viable alternative to steel laminations for a range of new applications, especially axial-flux wind generators. The isotropic nature of the SMC combined with the unique shaping possibilities opens up new design solutions for axial-flux wind generators. Through careful design, an axial-flux PM wind generator with SMC core is built and tested, demonstrating the

  17. Innovative Sensors for Pipeline Crawlers: Rotating Permanent Magnet Inspection

    Energy Technology Data Exchange (ETDEWEB)

    J. Bruce Nestleroth; Richard J. Davis; Stephanie Flamberg

    2006-09-30

    Internal inspection of pipelines is an important tool for ensuring safe and reliable delivery of fossil energy products. Current inspection systems that are propelled through the pipeline by the product flow cannot be used to inspect all pipelines because of the various physical barriers they may encounter. To facilitate inspection of these ''unpiggable'' pipelines, recent inspection development efforts have focused on a new generation of powered inspection platforms that are able to crawl slowly inside a pipeline and can maneuver past the physical barriers that limit internal inspection applicability, such as bore restrictions, low product flow rate, and low pressure. The first step in this research was to review existing inspection technologies for applicability and compatibility with crawler systems. Most existing inspection technologies, including magnetic flux leakage and ultrasonic methods, had significant implementation limitations including mass, physical size, inspection energy coupling requirements and technology maturity. The remote field technique was the most promising but power consumption was high and anomaly signals were low requiring sensitive detectors and electronics. After reviewing each inspection technology, it was decided to investigate the potential for a new inspection method. The new inspection method takes advantage of advances in permanent magnet strength, along with their wide availability and low cost. Called rotating permanent magnet inspection (RPMI), this patent pending technology employs pairs of permanent magnets rotating around the central axis of a cylinder to induce high current densities in the material under inspection. Anomalies and wall thickness variations are detected with an array of sensors that measure local changes in the magnetic field produced by the induced current flowing in the material. This inspection method is an alternative to the common concentric coil remote field technique that induces

  18. Development of nanostructured CoFe-based alloys for high temperature magnetic applications.

    Science.gov (United States)

    Panda, A K; Mohanta, O; Ghosh, M; Mitra, A

    2009-09-01

    The effect of substituting Fe by Co on the crystallization, structural and magnetic behaviour of Fe(72-x)Co(x)Si4B20Nb4 (X = 10, 20, 36, 50 at%) and Co36Fe36Si(4-Y)Al(y)B20Nb4 (Y = 0, 1 at%) alloys prepared in the form of melt spun ribbons has been discussed. Alloys containing optimum content of cobalt = 36 at% showed consistent coercivity at elevated temperatures. This soft magnetic property was further improved with aluminium incorporation. Transmission electron microscopy (TEM) indicated that such enhancement in the properties was due to finer dispersions of (CoFe)SiAl nanoparticles in amorphous matrix. Nanocrystallisation also raised the Curie temperature of the aluminium contained alloy.

  19. High-temperature electromagnons in the magnetically induced multiferroic cupric oxide driven by intersublattice exchange.

    Science.gov (United States)

    Jones, S P P; Gaw, S M; Doig, K I; Prabhakaran, D; Hétroy Wheeler, E M; Boothroyd, A T; Lloyd-Hughes, J

    2014-04-29

    Magnetically induced ferroelectric multiferroics present an exciting new paradigm in the design of multifunctional materials, by intimately coupling magnetic and polar order. Magnetoelectricity creates a novel quasiparticle excitation--the electromagnon--at terahertz frequencies, with spectral signatures that unveil important spin interactions. To date, electromagnons have been discovered at low temperature (domain spectroscopy that intersublattice exchange in the improper multiferroic cupric oxide (CuO) creates electromagnons at substantially elevated temperatures (213-230 K). Dynamic magnetoelectric coupling can therefore be achieved in materials, such as CuO, that exhibit minimal static cross-coupling. The electromagnon strength and energy track the static polarization, highlighting the importance of the underlying cycloidal spin structure. Polarized neutron scattering and terahertz spectroscopy identify a magnon in the antiferromagnetic ground state, with a temperature dependence that suggests a significant role for biquadratic exchange.

  20. Evidence for entanglement at high temperatures in an engineered molecular magnet

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Mario S [Universidade Federal Fluminense, Brasil; Soriano, Stephane [Universidade Federal Fluminense, Brasil; Moreira Dos Santos, Antonio F [ORNL; Sales, Brian C [ORNL; Soares-Pinto, D O [Centro Brasileiro de Pesquisas Fisicas (CBPF); Brandao, Paula [University of Aveiro, Portugal

    2012-01-01

    The molecular compound [Fe-2(mu(2)-oxo)(C3H4N2)(6)(C2O4)(2)] was designed and synthesized for the first time and its structure was determined using single-crystal X-ray diffraction. The magnetic susceptibility of this compound was measured from 2 to 300 K. The analysis of the susceptibility data using protocols developed for other spin singlet ground-state systems indicates that the quantum entanglement would remain at temperatures up to 732 K, significantly above the highest entanglement temperature reported to date. The large gap between the ground state and the first-excited state (282 K) suggests that the spin system may be somewhat immune to decohering mechanisms. Our measurements strongly suggest that molecular magnets are promising candidate platforms for quantum information processing.

  1. High-Temperature Spintronic Devices and Circuits in Absence of Magnetic Field

    Science.gov (United States)

    2012-04-23

    the output exhibits linear polarization which decays to zero at 1 T. The measured degree of circular polarization is determined by the magnetization...subsequent layers to avoid interlay er diffusion of Mn atoms and formation of Mn-Mn clusters . The Mn atoms allow low temperature p-doping of GaAs...Tunneling across the source and drain Schottky barriers is analyzed with the Tsu-Esaki model using the WKB approximation and assuming that

  2. Optimization of Multibrid Permanent-Magnet Wind Generator Systems

    DEFF Research Database (Denmark)

    Chen, Zhe; Li, H.; Polinder, H.

    2009-01-01

    This paper investigates the cost-effective ranges of gearbox ratios and power ratings of multibrid permanent-magnet (PM) wind generator systems by using a design optimization method. First, the analytical model of a multibrid wind turbine concept consisting of a single-stage gearbox and a three......-phase radial-flux PM synchronous generator with a back-to-back power converter is presented. The design optimization is adopted with a genetic algorithm forminimizing generator system cost. To demonstrate the effectiveness of the developed electromagnetic design model, the optimization results of a 500-k......W direct-drive PM generator and a 1.5-MW multibrid PM generator with various gear ratios are, respectively, compared with those from other methods. Then, the optimal design approach is further employed for a range from 750 kW up to 10 MW. The optimization results of PM generator systems including direct...

  3. A double-sided linear primary permanent magnet vernier machine.

    Science.gov (United States)

    Du, Yi; Zou, Chunhua; Liu, Xianxing

    2015-01-01

    The purpose of this paper is to present a new double-sided linear primary permanent magnet (PM) vernier (DSLPPMV) machine, which can offer high thrust force, low detent force, and improved power factor. Both PMs and windings of the proposed machine are on the short translator, while the long stator is designed as a double-sided simple iron core with salient teeth so that it is very robust to transmit high thrust force. The key of this new machine is the introduction of double stator and the elimination of translator yoke, so that the inductance and the volume of the machine can be reduced. Hence, the proposed machine offers improved power factor and thrust force density. The electromagnetic performances of the proposed machine are analyzed including flux, no-load EMF, thrust force density, and inductance. Based on using the finite element analysis, the characteristics and performances of the proposed machine are assessed.

  4. Zeeman slowers for strontium based on permanent magnets

    Science.gov (United States)

    Hill, Ian R.; Ovchinnikov, Yuri B.; Bridge, Elizabeth M.; Curtis, E. Anne; Gill, Patrick

    2014-04-01

    We present the design, construction, and characterization of longitudinal- and transverse-field Zeeman slowers, based on arrays of permanent magnets, for slowing thermal beams of atomic Sr. The slowers are optimized for operation with deceleration related to the local laser intensity (by the parameter ɛ), which uses more effectively the available laser power, in contrast to the usual constant deceleration mode. Slowing efficiencies of up to ≈18% are realized and compared to those predicted by modelling. We highlight the transverse-field slower, which is compact, highly tunable, light-weight, and requires no electrical power, as a simple solution to slowing Sr, well-suited to space-borne application. For 88Sr we achieve a slow-atom flux of around 6 × 109 atoms s-1 at 30 ms-1, loading approximately 5 × 108 atoms in to a magneto-optical-trap, and capture all isotopes in approximate relative natural abundances.

  5. Zeeman Slowers for Strontium based on Permanent Magnets

    CERN Document Server

    Hill, Ian R; Bridge, Elizabeth M; Curtis, E Anne; Gill, Patrick

    2014-01-01

    We present the design, construction, and characterisation of longitudinal- and transverse-field Zeeman slowers, based on arrays of permanent magnets, for slowing thermal beams of atomic Sr. The slowers are optimised for operation with deceleration related to the local laser intensity (by the parameter $\\epsilon$), which uses more effectively the available laser power, in contrast to the usual constant deceleration mode. Slowing efficiencies of up to $\\approx$ $18$ $%$ are realised and compared to those predicted by modelling. We highlight the transverse-field slower, which is compact, highly tunable, light-weight, and requires no electrical power, as a simple solution to slowing Sr, well-suited to spaceborne application. For $^{88}$Sr we achieve a slow-atom flux of around $6\\times 10^9$ atoms$\\,$s$^{-1}$ at $30$ ms$^{-1}$, loading approximately $5\\times 10^8$ atoms in to a magneto-optical-trap (MOT), and capture all isotopes in approximate relative natural abundances.

  6. A Double-Sided Linear Primary Permanent Magnet Vernier Machine

    Directory of Open Access Journals (Sweden)

    Yi Du

    2015-01-01

    Full Text Available The purpose of this paper is to present a new double-sided linear primary permanent magnet (PM vernier (DSLPPMV machine, which can offer high thrust force, low detent force, and improved power factor. Both PMs and windings of the proposed machine are on the short translator, while the long stator is designed as a double-sided simple iron core with salient teeth so that it is very robust to transmit high thrust force. The key of this new machine is the introduction of double stator and the elimination of translator yoke, so that the inductance and the volume of the machine can be reduced. Hence, the proposed machine offers improved power factor and thrust force density. The electromagnetic performances of the proposed machine are analyzed including flux, no-load EMF, thrust force density, and inductance. Based on using the finite element analysis, the characteristics and performances of the proposed machine are assessed.

  7. Force prediction in permanent magnet flat linear motors (abstract)

    Science.gov (United States)

    Eastham, J. F.; Akmese, R.

    1991-11-01

    The advent of neodymium iron boron rare-earth permanent magnet material has afforded the opportunity to construct linear machines of high force to weight ratio. The paper describes the design and construction of an axial flux machine and rotating drum test rig. The machine occupies an arc of 45° on a drum 1.22 m in diameter. The excitation is provided by blocks of NdFeB material which are skewed in order to minimize the force variations due to slotting. The stator carries a three-phase short-chorded double-layer winding of four poles. The machine is supplied by a PWM inverter the fundamental component of which is phase locked to the rotor position so that a ``dc brushless'' drive system is produced. Electromagnetic forces including ripple forces are measured at supply frequencies up to 100 Hz. They are compared with finite-element analysis which calculates the force variation over the time period. The paper then considers some of the causes of ripple torque. In particular, the force production due solely to the permanent magnet excitation is considered. This has two important components each acting along the line of motion of the machine, one is due to slotting and the other is due to the finite length of the primary. In the practical machine the excitation poles are skewed to minimize the slotting force and the effectiveness of this is confirmed by both results from the experiments and the finite-element analysis. The end effect force is shown to have a space period of twice that of the excitation. The amplitude of this force and its period are again confirmed by practical results.

  8. Method for improving performance of high temperature superconductors within a magnetic field

    Science.gov (United States)

    Wang, Haiyan; Foltyn, Stephen R.; Maiorov, Boris A.; Civale, Leonardo

    2010-01-05

    The present invention provides articles including a base substrate including a layer of an oriented cubic oxide material having a rock-salt-like structure layer thereon; and, a buffer layer upon the oriented cubic oxide material having a rock-salt-like structure layer, the buffer layer having an outwardly facing surface with a surface morphology including particulate outgrowths of from 10 nm to 500 run in size at the surface, such particulate outgrowths serving as flux pinning centers whereby the article maintains higher performance within magnetic fields than similar articles without the necessary density of such outgrowths.

  9. Effects of strong magnetic fields on pairing fluctuations in high-temperature superconductors

    OpenAIRE

    Eschrig, Matthias; Rainer, D.; Sauls, J. A.

    1999-01-01

    We present the theory for the effects of superconducting pairing fluctuations on the nuclear spin-lattice relaxation rate 1/T1 and the NMR Knight shift for layered superconductors in high magnetic fields. These results can be used to clarify the origin of the pseudogap in high-Tc cuprates, which has been attributed to spin fluctuations as well as pairing fluctuations. We present theoretical results for s-wave and d-wave pairing fluctuations and show that recent experiments in optimally doped ...

  10. Exploring high temperature magnetic order in CeTi_1-xSc_xGe

    OpenAIRE

    2014-01-01

    Most of magnetic transitions related to Ce ordering are found below T_ord~12K. Among the few cases exceeding that temperature, two types of behaviors can be distinguished. One of them is related to the rare cases of Ce binary compounds formed in BCC structures, with a quartet ground state, whose degeneracy is reduced by undergoing different types of transitions mostly structural. The other group shows evidences of itinerant character with the outstanding example of CeRh_3B_2 showing the highe...

  11. Economic viability, applications and limits of efficient permanent magnet motors - Summary and update; Wirtschaftlichkeit, Anwendungen und Grenzen von effizienten Permanent-Magnet-Motoren - Zusammenfassung und Update - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Lindegger, M. [Circle Motor AG, Guemligen (Switzerland); Biner, H.-P.; Evequoz, B. [Hochschule Westschweiz, Delemont (Switzerland); Salathe, D. [Hochschule Luzern Technik und Architektur, Horw (Switzerland)

    2009-06-15

    This final report for the Swiss Federal Office of Energy (SFOE), takes a look at the economic viability, applications and limits of efficient permanent magnet motors. Permanent magnet motors are compared with standard IEC asynchronous motors. In a theoretical part of the report, it is discussed how the increasing size of the motor influences efficiency, weight, volume and power. The results of practical tests carried out on six motors are presented. Three standard motors with varying efficiency were compared with three permanent-magnet motors for the power range around 3 kW. Market-oriented considerations concerning permanent-magnet motors are discussed. Operational criteria for the choice of the type of motor to be used are also examined.

  12. Computing the External Magnetic Scalar Potential due to an Unbalanced Six-Pole Permanent Magnet Motor

    Energy Technology Data Exchange (ETDEWEB)

    Selvaggi J, Salon S, Kwon O, Chari MVK

    2007-02-12

    The accurate computation of the external magnetic field from a permanent magnet motor is accomplished by first computing its magnetic scalar potential. In order to find a solution which is valid for any arbitrary point external to the motor, a number of proven methods have been employed. Firstly, A finite element model is developed which helps generate magnetic scalar potential values valid for points close to and outside the motor. Secondly, charge simulation is employed which generates an equivalent magnetic charge matrix. Finally, an equivalent multipole expansion is developed through the application of a toroidal harmonic expansion. This expansion yields the harmonic components of the external magnetic scalar potential which can be used to compute the magnetic field at any point outside the motor.

  13. Exploring high temperature magnetic order in CeTi1-xScxGe

    Science.gov (United States)

    Sereni, J. G.; Pedrazzini, P.; Gómez Berisso, M.; Chacoma, A.; Encina, S.; Gruner, T.; Caroca-Canales, N.; Geibel, C.

    2015-03-01

    We studied the magnetic, transport, and thermodynamic properties of the alloy CeTi1-xScxGe in order to shed some light into the origin of the exceptionally large antiferromagnetic (AFM) ordering temperature TN = 47 K in pure CeScGe. We observed a complex magnetic phase diagram, which present an interesting dichotomy: Despite strong changes in the nature of the ordered state, from ferromagnetic (FM) for x 0.55, the ordering temperature increases smoothly and continuously from TC = 7 K at x = 0.25 to TN = 47 K at x = 1. Within the AFM regime we observe a metamagnetic transition at a critical field increasing from H = 0 at x ≈ 0.55 to μ0 * H ≈ 6 Tesla at x = 1. Furthermore a second transition appears at TL = 0.65. In contrast to observations in CeRh2Si2 or CeRh3B2, we found no evidence for a strong hybridization of the 4f electrons at large Sc contents. Therefore the exceptionally large TN of CeScGe could be attributed to the unusually strong RKKY interaction in this type of compounds.

  14. Thickness dependence of the levitation performance of double-layer high-temperature superconductor bulks above a magnetic rail

    Energy Technology Data Exchange (ETDEWEB)

    Sun, R.X.; Zheng, J.; Liao, X.L.; Che, T.; Gou, Y.F.; He, D.B.; Deng, Z.G., E-mail: zgdeng@gmail.com

    2014-10-15

    Highlights: • Thickness optimization of double-layer bulk HTSC arrangement is studied. • The new bulk HTSC arrangement makes better use of the flux distribution of the magnetic rails. • Levitation performance can be enhanced with the optimization. • The optimization can meet large levitation force requirements for HTS Maglev system. - Abstract: A double-layer high-temperature superconductor (HTSC) arrangement was proposed and proved to be able to bring improvements to both levitation force and guidance force compared with present single-layer HTSC arrangement. To fully exploit the applied magnetic field by a magnetic rail, the thickness dependence of a double-layer HTSC arrangement on the levitation performance was further investigated in the paper. In this study, the lower-layer bulk was polished step by step to different thicknesses, and the upper-layer bulk with constant thickness was directly superimposed on the lower-layer one. The levitation force and the force relaxation of the double-layer HTSC arrangement were measured above a Halbach magnetic rail. Experimental result shows that a bigger levitation force and a less levitation force decay could be achieved by optimizing the thickness of the lower-layer bulk HTSC. This thickness optimization method could be applied together with former reported double-layer HTSC arrangement method with aligned growth sector boundaries pattern. This series of study on the optimized combination method do bring a significant improvement on the levitation performance of present HTS maglev systems.

  15. Design and Maxwell 3D simulation of small permanent magnetic actuator

    Institute of Scientific and Technical Information of China (English)

    Zhang Guangcai; Xu Yajie; Chang Yan; Chen Qiaoyan; Yang Xiaodong

    2014-01-01

    According to the magnetic circuit design theory and performance requirements of magnetic field, an H-type permanent magnetic actuator that generates uniform magnetic field larger than 0.4 T in the interested re- gion has been designed in this paper. The static magnetic field simulation analysis was done by Ansoft' s Max- well three-dimensional (3D) software. The simulation results showed that the magnetic field of this system can meet the requirements, and this permanent magnetic actuator designed in this paper can be used in small nuclear magnetic resonance (NMR) svstem.

  16. Topology optimized and 3D printed polymer-bonded permanent magnets for a predefined external field

    Science.gov (United States)

    Huber, C.; Abert, C.; Bruckner, F.; Pfaff, C.; Kriwet, J.; Groenefeld, M.; Teliban, I.; Vogler, C.; Suess, D.

    2017-08-01

    Topology optimization offers great opportunities to design permanent magnetic systems that have specific external field characteristics. Additive manufacturing of polymer-bonded magnets with an end-user 3D printer can be used to manufacture permanent magnets with structures that had been difficult or impossible to manufacture previously. This work combines these two powerful methods to design and manufacture permanent magnetic systems with specific properties. The topology optimization framework is simple, fast, and accurate. It can also be used for the reverse engineering of permanent magnets in order to find the topology from field measurements. Furthermore, a magnetic system that generates a linear external field above the magnet is presented. With a volume constraint, the amount of magnetic material can be minimized without losing performance. Simulations and measurements of the printed systems show very good agreement.

  17. The study, design and testing of a linear oscillating generator with moving permanent magnets

    Directory of Open Access Journals (Sweden)

    Teodora Susana Oros (Pop

    2015-12-01

    Full Text Available This paper presents a study, design and testing of a Linear Oscillating Generator. There are presented the main steps of the magnetic and electric calculations for a permanent magnet linear alternator of fixed coil and moving magnets type. Finally it has been shown the comparative analysis between the linear oscillating generator with moving permanent magnets in no load operation and load operation.

  18. Analysis of a Permanent-Magnet Brushless DC Motor with Fixed Dimensions

    Science.gov (United States)

    Brakanskis, Uldis; Dirba, Janis; Kukjane, Ludmila; Drava, Viesturs

    2010-01-01

    The purpose of this paper is to describe the analysis of a permanent-magnet brushless DC motor with fixed outer diameter and active zone length. The influence of air gap, material of permanent magnets and their size on the magnetic flux density of the machine and magnetic flux is analyzed. The work presents the calculations of two programs, the comparison of the results and the most suitable combination of factors that has been found.

  19. Analytical Calculation of the Magnetic Field distribution in a Flux-Modulated Permanent-Magnet Brushless Motor

    DEFF Research Database (Denmark)

    Zhang, Xiaoxu; Liu, Xiao; Chen, Zhe

    2015-01-01

    This paper presents a rapid approach to compute the magnetic field distribution in a flux-modulated permanent-magnet brushless motor. Partial differential equations are used to describe the magnet field behavior in terms of magnetic vector potentials. The whole computational domain is divided int...... magnetic field with those calculated by finite element method....

  20. Anomalous magneto-structural behavior of MnBi explained: A path towards an improved permanent magnet

    Directory of Open Access Journals (Sweden)

    N. A. Zarkevich

    2014-03-01

    Full Text Available Low-temperature MnBi (hexagonal NiAs phase exhibits anomalies in the lattice constants (a, c and bulk elastic modulus (B below 100 K, spin reorientation and magnetic susceptibility maximum near 90 K, and, importantly for high-temperature magnetic applications, an increasing coercivity (unique to MnBi above 180  K. We calculate the total energy and magneto-anisotropy energy (MAE versus (a, c using DFT+U methods. We reproduce and explain all the above anomalies. We predict that coercivity and MAE increase due to increasing a, suggesting means to improve MnBi permanent magnets.

  1. Levitation and Guidance Characteristics of the Permanent magnet-HTSC Hybrid Magnetic Conveyance System

    Science.gov (United States)

    Ohashi, Shunsuke; Dodo, Daiki

    Hybrid magnetically levitated transportation system has been developed. The magnetic rail is set on the ground, and the carrier with permanent magnets and high-Tc superconductors (HTSC) levitates on the rail. In this system, pinning force of HTSC and repulsive force of permanent magnet is combined. Repulsive force of permanent magnet is introduced to support weight. Pinning force is used to support weight of the frame of the carrier and to achieve lateral stability of the carrier. To decrease influence of weight on the levitation gap of the carrier, the weight stage is fixed to the carrier frame by linear sliders, and moves freely for vertical direction. As a result, there is little influence on levitation gap of the carrier. Basic levitation and guidance characteristics of the system are shown. Repulsive force generates very large levitation force. It also generates unstable lateral force. Weight added to the carrier has some influence on lateral stability. Although lateral position recovery force by pinning effect decreases at a heavier weight, the carrier shows enough force to keep lateral stability.

  2. Torque Analysis With Saturation Effects for Non-Salient Single-Phase Permanent-Magnet Machines

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Ritchie, Ewen

    2011-01-01

    The effects of saturation on torque production for non-salient, single-phase, permanent-magnet machines are studied in this paper. An analytical torque equation is proposed to predict the instantaneous torque with saturation effects. Compared to the existing methods, it is computationally faster......-element results, and experimental results obtained on a prototype single-phase permanent-magnet machine....

  3. Influence of End-Effects on Static Torque Performance of Misaligned Cylindrical Permanent Magnet Couplings

    DEFF Research Database (Denmark)

    Högberg, Stig; Hansen, Hilary; Jensen, Bogi Bech;

    2014-01-01

    Permanent magnet couplings are widely used in applications requiring torque to be transmitted through an air- gap. The aim of this study is to observe and explain the effect of radial and axial misalignment in a 12-pole, cylindrical permanent magnet coupling. Pull-out torque was measured for two...

  4. Improved cost of energy comparison of permanent magnet generators for large offshore wind turbines

    NARCIS (Netherlands)

    Hart, K.; McDonald, A.; Polinder, H.; Corr, E.; Carroll, J.

    2014-01-01

    This paper investigates geared and direct-drive permanent magnet generators for a typical offshore wind turbine, providing a detailed comparison of various wind turbine drivetrain configurations in order to minimise the Cost of Energy. The permanent magnet generator topologies considered include a d

  5. Improved cost of energy comparison of permanent magnet generators for large offshore wind turbines

    NARCIS (Netherlands)

    Hart, K.; McDonald, A.; Polinder, H.; Corr, E.; Carroll, J.

    2014-01-01

    This paper investigates geared and direct-drive permanent magnet generators for a typical offshore wind turbine, providing a detailed comparison of various wind turbine drivetrain configurations in order to minimise the Cost of Energy. The permanent magnet generator topologies considered include a

  6. Optimal Design of Stator Interior Permanent Magnet Machine with Minimized Cogging Torque for Wind Power Application

    DEFF Research Database (Denmark)

    Chen, Zhe; Zhang, Jianzhong; Cheng, Ming

    2008-01-01

    This paper proposes a new approach to minimize the cogging torque of a stator interior permanent magnet (SIPM) machine. The optimization of stator slot gap and permanent magnet is carried out and the cogging torque ripple is analyzed by using finite element analysis. Experiments on a prototype...

  7. A National Collaboratory to Advance the Science of High Temperature Plasma Physics for Magnetic Fusion

    Energy Technology Data Exchange (ETDEWEB)

    Schissel, David P. [Princeton Plasma Physics Lab., NJ (United States); Abla, G. [Princeton Plasma Physics Lab., NJ (United States); Burruss, J. R. [Princeton Plasma Physics Lab., NJ (United States); Feibush, E. [Princeton Plasma Physics Lab., NJ (United States); Fredian, T. W. [Massachusetts Institute of Technology, Cambridge, MA (United States); Goode, M. M. [Lawrence Berkeley National Lab., CA (United States); Greenwald, M. J. [Massachusetts Institute of Technology, Cambridge, MA (United States); Keahey, K. [Argonne National Lab., IL (United States); Leggett, T. [Argonne National Lab., IL (United States); Li, K. [Princeton Univ., NJ (United States); McCune, D. C. [Princeton Plasma Physics Lab., NJ (United States); Papka, M. E. [Argonne National Lab., IL (United States); Randerson, L. [Princeton Plasma Physics Lab., NJ (United States); Sanderson, A. [Univ. of Utah, Salt Lake City, UT (United States); Stillerman, J. [Massachusetts Institute of Technology, Cambridge, MA (United States); Thompson, M. R. [Lawrence Berkeley National Lab., CA (United States); Uram, T. [Argonne National Lab., IL (United States); Wallace, G. [Princeton Univ., NJ (United States)

    2012-12-20

    This report summarizes the work of the National Fusion Collaboratory (NFC) Project to develop a persistent infrastructure to enable scientific collaboration for magnetic fusion research. The original objective of the NFC project was to develop and deploy a national FES Grid (FusionGrid) that would be a system for secure sharing of computation, visualization, and data resources over the Internet. The goal of FusionGrid was to allow scientists at remote sites to participate as fully in experiments and computational activities as if they were working on site thereby creating a unified virtual organization of the geographically dispersed U.S. fusion community. The vision for FusionGrid was that experimental and simulation data, computer codes, analysis routines, visualization tools, and remote collaboration tools are to be thought of as network services. In this model, an application service provider (ASP provides and maintains software resources as well as the necessary hardware resources. The project would create a robust, user-friendly collaborative software environment and make it available to the US FES community. This Grid's resources would be protected by a shared security infrastructure including strong authentication to identify users and authorization to allow stakeholders to control their own resources. In this environment, access to services is stressed rather than data or software portability.

  8. Anomalous results observed in magnetization of bulk high temperature superconductors—A windfall for applications

    Science.gov (United States)

    Weinstein, Roy; Parks, Drew; Sawh, Ravi-Persad; Carpenter, Keith; Davey, Kent

    2016-04-01

    Recent experiments on pulsed-zero field cool magnetization of bulk high Jc YBCO (YBa2Cu3O7-δ) have shown unexpected results. For example, reproducible, non-destructive, rapid, giant field leaps (GFLs) to higher penetrated field are observed. The observations are inconsistent with the critical state model (CSM), in several aspects. Additional experiments have been pursued in an attempt to clarify the physics involved in the observed anomalies. Here, we present experimental results for the Jc dependence of the anomalous features. It is found that the sudden field increase in the GFL is a monotonically increasing function of Jc. The ratio of required pulsed field amplitude, BA,max, to obtain maximum trappable field, BT,max, which CSM predicts to be ≥2.0, gradually approaches 1.0 at high Jc. Tests using values of pulsed, applied field BA,max just below the GFL exhibit two additional anomalies: (i) At high Jc, the highest trapped field is up to ˜6 times lower than predicted by CSM, and (ii) the measured Lorentz force as a function of Jc deviates sharply from CSM predictions. The data rule out heating effects and pinning center geometry as possible physical causes of these anomalies. A speculative cause is considered.

  9. Magnetic force microscope study on anisotropic NdFeB permanent magnets

    Institute of Scientific and Technical Information of China (English)

    刘薇; 蒋建华; 吴建生; 李刚

    2003-01-01

    NdFeB permanent magnets prepared by powder metallurgy were investigated using magnetic force microscopy(MFM).The excellent MFM images of sample along the surfaces parallel and perpendicular to the alignment axis were collected respectively.The results show the necessity of annealing procedure in the preparation of the samples to remove the polishing surface stress and to illustrate the real magnetic domain structure,so that the much information about both the magnetic structure and the topographic microstructure is obtained.The hard MFM tip is verified to be effective for this material especially for the sample with the examined surface parallel to alignment axis.By analyzing these well-captured magnetic force images,magnetic domains and alignment degree as well as thetopographic information such as grain size and the nonmagnetic phases at the grain boundaries were demonstrated.

  10. Effect of axial magnetic field on a 2.45 GHz permanent magnet ECR ion source

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, T., E-mail: tsubasa@oshima-k.ac.jp; Wada, H.; Furuse, M. [National Institute of Technology, Oshima College, 1091-1 Komatsu, Suouoshima, Oshima, Yamaguchi 742-2193 (Japan); Asaji, T. [National Institute of Technology, Toyama College, 13 Hongo, Toyama 939-8630 (Japan)

    2016-02-15

    Herein, we conduct a fundamental study to improve the generation efficiency of a multi-charged ion source using argon. A magnetic field of our electron cyclotron resonance ion source is composed of a permanent magnet and a solenoid coil. Thereby, the axial magnetic field in the chamber can be tuned. Using the solenoid coil, we varied the magnetic field strength in the plasma chamber and measured the ion beam current extracted at the electrode. We observed an approximately three times increase in the Ar{sup 4+} ion beam current when the magnetic field on the extractor-electrode side of the chamber was weakened. From our results, we can confirm that the multi-charged ion beam current changes depending on magnetic field intensity in the plasma chamber.

  11. Magnetized sheath near positively biased wall between two permanent magnetic plates

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yan; Wei, Zi-an; Ma, J. X., E-mail: jxma@ustc.edu.cn; Jiang, Zheng-qi; Wu, Fei [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); CAS Key Laboratory of Geospace Environment, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-06-15

    The characteristics of magnetized electron sheath near a positively biased conducting wall parallel to magnetic field formed between two permanent magnetic plates were experimentally investigated in a double plasma device. The magnetic field strength between the magnetic plates is about 1200 G which is sufficient to magnetize the plasma such that the ion gyroradius is comparable to the electron Debye length. A virtual cathode (or potential dip) structure was found between the electron-rich sheath and bulk plasma. For a given neutral gas pressure, the potential minimum (dip position) remains almost the same for different positive biases on the wall. For a given bias on the wall, however, the electron sheath thickness and the potential drop from the bulk plasma to the dip decrease with the increase of the neutral gas pressure. In addition, the electron sheath and potential dip appear to be wider and deeper in the downstream side of the wall.

  12. First Ever Storage of Ultracold Neutrons in a Magnetic Trap Made of Permanent Magnets.

    Science.gov (United States)

    Ezhov, V F; Andreev, A Z; Glushkov, A A; Glushkov, A G; Groshev, M N; Knyazkov, V A; Krygin, G B; Ryabov, V L; Serebrov, A P; Bazarov, B A; Geltenbort, P; Hartman, F J; Paul, S; Picker, R; Zimmer, O; Kovrizhnykh, N A

    2005-01-01

    Further improvement in the accuracy of any neutron lifetime experiment by means of ultracold neutrons (UCN) in material bottles is limited due to unavoidable systematic effects when the UCN are reflected from the walls. However, such effects can be excluded in principle if magnetic trapping of UCN is used. The storage of UCN in a small magnetic trap made of permanent magnets was demonstrated for the first time ever. The measured storage time in this feasibility study was (882 ± 16) s. At this level of accuracy no depolarization was observed.

  13. Induction heating of rotating nonmagnetic billet in magnetic field produced by high-parameter permanent magnets

    Directory of Open Access Journals (Sweden)

    Ivo Doležel

    2014-04-01

    Full Text Available An advanced way of induction heating of nonmagnetic billets is discussed and modeled. The billet rotates in a stationary magnetic field produced by unmoving high-parameter permanent magnets fixed on magnetic circuit of an appropriate shape. The mathematical model of the problem consisting of two coupled partial differential equations is solved numerically, in the monolithic formulation. Computations are carried out using our own code Agros2D based on a fully adaptive higher-order finite element method. The most important results are verified experimentally on our own laboratory device.

  14. Large-Area Permanent-Magnet ECR Plasma Source

    Science.gov (United States)

    Foster, John E.

    2007-01-01

    A 40-cm-diameter plasma device has been developed as a source of ions for material-processing and ion-thruster applications. Like the device described in the immediately preceding article, this device utilizes electron cyclotron resonance (ECR) excited by microwave power in a magnetic field to generate a plasma in an electrodeless (noncontact) manner and without need for an electrically insulating, microwave-transmissive window at the source. Hence, this device offers the same advantages of electrodeless, windowless design - low contamination and long operational life. The device generates a uniform, high-density plasma capable of sustaining uniform ion-current densities at its exit plane while operating at low pressure [magnetic field in this device is generated by a permanent-magnet circuit that is optimized to generate resonance surfaces. The microwave power is injected on the centerline of the device. The resulting discharge plasma jumps into a "high mode" when the input power rises above 150 W. This mode is associated with elevated plasma density and high uniformity. The large area and uniformity of the plasma and the low operating pressure are well suited for such material-processing applications as etching and deposition on large silicon wafers. The high exit-plane ion-current density makes it possible to attain a high rate of etching or deposition. The plasma potential is <3 V low enough that there is little likelihood of sputtering, which, in plasma processing, is undesired because it is associated with erosion and contamination. The electron temperature is low and does not vary appreciably with power.

  15. A NATIONAL COLLABORATORY TO ADVANCE THE SCIENCE OF HIGH TEMPERATURE PLASMA PHYSICS FOR MAGNETIC FUSION

    Energy Technology Data Exchange (ETDEWEB)

    Allen R. Sanderson; Christopher R. Johnson

    2006-08-01

    This report summarizes the work of the University of Utah, which was a member of the National Fusion Collaboratory (NFC) Project funded by the United States Department of Energy (DOE) under the Scientific Discovery through Advanced Computing Program (SciDAC) to develop a persistent infrastructure to enable scientific collaboration for magnetic fusion research. A five year project that was initiated in 2001, it the NFC built on the past collaborative work performed within the U.S. fusion community and added the component of computer science research done with the USDOE Office of Science, Office of Advanced Scientific Computer Research. The project was itself a collaboration, itself uniting fusion scientists from General Atomics, MIT, and PPPL and computer scientists from ANL, LBNL, and Princeton University, and the University of Utah to form a coordinated team. The group leveraged existing computer science technology where possible and extended or created new capabilities where required. The complete finial report is attached as an addendum. The In the collaboration, the primary technical responsibility of the University of Utah in the collaboration was to develop and deploy an advanced scientific visualization service. To achieve this goal, the SCIRun Problem Solving Environment (PSE) is used on FusionGrid for an advanced scientific visualization service. SCIRun is open source software that gives the user the ability to create complex 3D visualizations and 2D graphics. This capability allows for the exploration of complex simulation results and the comparison of simulation and experimental data. SCIRun on FusionGrid gives the scientist a no-license-cost visualization capability that rivals present day commercial visualization packages. To accelerate the usage of SCIRun within the fusion community, a stand-alone application built on top of SCIRun was developed and deployed. This application, FusionViewer, allows users who are unfamiliar with SCIRun to quickly create

  16. Magnetic properties of high temperature superconductors. AC susceptibility and magnetostriction studies

    Energy Technology Data Exchange (ETDEWEB)

    Heill, L.K.

    1995-05-01

    The author of this thesis has measured the ac magnetic response function {mu} = {mu}`+i{mu}`` in melt-powder-melt-growth YBa{sub 2}Cu{sub 3}O{sub 7} (Y123) with insulating Y{sub 2}BaCuO{sub 5} (Y211) and in single crystal YBa{sub 2}Cu{sub 3}O{sub 7} (SC) in applied dc fields up to 8 T, oriented both parallel and perpendicular to the crystalline c-axis. Both samples are cubes with sides of about 1 mm. The response of the two samples was mapped out as a function of temperature, excitation field amplitude and frequency, dc field and field orientation. It is found that for both samples the loss peak line (LPL) and hence the irreversibility line (IL) exists at higher temperatures and fields for perpendicular field orientation than for parallel. Strong frequency but weak amplitude dependence is observed for parallel orientation, vice versa for perpendicular orientation. The measured response is strongly non-linear for perpendicular orientation, and intermediate between linear (ohmic) and extremely non-linear (Bean critical state) for parallel orientation. The situation at parallel orientation is close to but above the transition into a vortex solid state, and a power law temperature dependence with exponent 1.5 is obtained for the vortex glass transition line. For perpendicular orientation the response is consistent with that expected in a vortex solid. Pinning barriers are found by means of thermal activation analysis. Anomalous loss peaks {mu}``(T) are observed for the SC sample for intermediate fields in perpendicular orientation. Large magnetostriction is found in a flat single crystal Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} sample at low temperature and fields up to 6 T applied along the c-axis. 332 refs., 59 figs., 7 tabs.

  17. High-gradient permanent magnet apparatus and its use in particle collection

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Mengdawn; Ludtka, Gerard Michael; Avens, Larry R.

    2016-07-12

    A high-gradient permanent magnet apparatus for capturing paramagnetic particles, the apparatus comprising: (i) at least two permanent magnets positioned with like poles facing each other; (ii) a ferromagnetic spacer separating the like poles; and (iii) a magnetizable porous filling material in close proximity to the at least two permanent magnets. Also described is a method for capturing paramagnetic particles in which a gas or liquid sample containing the paramagnetic particles is contacted with the high-gradient permanent magnet apparatus described above; wherein, during the contacting step, the gas or liquid sample contacts the magnetizable porous filling material of the high-gradient permanent magnet apparatus, and at least a portion of the paramagnetic particles in the gas or liquid sample is captured on the magnetizable porous filling material.

  18. Passive control of Permanent Magnet Synchronous Motor chaotic system based on state observer

    Institute of Scientific and Technical Information of China (English)

    QI Dong-lian; WANG Qiao

    2006-01-01

    Passive system theory was applied to propose a new passive control method with nonlinear observer of the Permanent Magnet Synchronous Motor chaotic system. Through constructing a Lyapunov function, the subsystem of the Permanent Magnet Synchronous Motor chaotic system could be proved to be globally stable at the equilibrium point. Then a controller with smooth state feedback is designed so that the Permanent Magnet Synchronous Motor chaotic system can be equivalent to a passive system.To get the state variables of the controller, the nonlinear observer is also studied. It is found that the outputs of the nonlinear observer can approximate the state variables of the Permanent Magnet Synchronous Motor chaotic system if the system's nonlinear function is a globally Lipschitz function. Simulation results showed that the equivalent passive system of Permanent Magnet Synchronous Motor chaotic system could be globally asymptotically stabilized by smooth state feedback in the observed parameter convergence condition area.

  19. Magnetic properties of La-Zn substituted Sr-hexaferrites by self-propagation high-temperature synthesis

    Institute of Scientific and Technical Information of China (English)

    YOU Lishun; QIAO Liang; ZHENG Jingwu; JIANG Meiyan; JIANG Liqiang; SHENG Jiawei

    2008-01-01

    The La-Zn substituted SrM-type ferrites with the composition of Sr1-xLaxFe12-xZnxO19 (x=0-0.4) were prepared by self-propagating high-temperature synthesis (SHS). The single SrM phase was detected by XRD in the as-received samples by controlling the Fe contents in the reagents. The substitution of La3+ and Zn2+ obviously increased the magnetic properties of the as-prepared samples. The maximum improvements of Br, Hcb and (BH)m were 14.4%, 15.3% and 30.7%, respectively compared with that of the samples without La-Zn substitution. Microstructure observation by SEM showed that the SHS method benefited forming the better particle features and achieving the higher Hcj in comparison with the traditional firing method.

  20. Processing of alnico permanent magnets by advanced directional solidification methods

    Science.gov (United States)

    Zou, Min; Johnson, Francis; Zhang, Wanming; Zhao, Qi; Rutkowski, Stephen F.; Zhou, Lin; Kramer, Matthew J.

    2016-12-01

    Advanced directional solidification methods have been used to produce large (>15 cm length) castings of Alnico permanent magnets with highly oriented columnar microstructures. In combination with subsequent thermomagnetic and draw thermal treatment, this method was used to enable the high coercivity, high-Titanium Alnico composition of 39% Co, 29.5% Fe, 14% Ni, 7.5% Ti, 7% Al, 3% Cu (wt%) to have an intrinsic coercivity (Hci) of 2.0 kOe, a remanence (Br) of 10.2 kG, and an energy product (BH)max of 10.9 MGOe. These properties compare favorably to typical properties for the commercial Alnico 9. Directional solidification of higher Ti compositions yielded anisotropic columnar grained microstructures if high heat extraction rates through the mold surface of at least 200 kW/m2 were attained. This was achieved through the use of a thin walled (5 mm thick) high thermal conductivity SiC shell mold extracted from a molten Sn bath at a withdrawal rate of at least 200 mm/h. However, higher Ti compositions did not result in further increases in magnet performance. Images of the microstructures collected by scanning electron microscopy (SEM) reveal a majority α phase with inclusions of secondary αγ phase. Transmission electron microscopy (TEM) reveals that the α phase has a spinodally decomposed microstructure of FeCo-rich needles in a NiAl-rich matrix. In the 7.5% Ti composition the diameter distribution of the FeCo needles was bimodal with the majority having diameters of approximately 50 nm with a small fraction having diameters of approximately 10 nm. The needles formed a mosaic pattern and were elongated along one crystal direction (parallel to the field used during magnetic annealing). Cu precipitates were observed between the needles. Regions of abnormal spinodal morphology appeared to correlate with secondary phase precipitates. The presence of these abnormalities did not prevent the material from displaying superior magnetic properties in the 7.5% Ti composition

  1. Upgrading of High-Aluminum Hematite-Limonite Ore by High Temperature Reduction-Wet Magnetic Separation Process

    Directory of Open Access Journals (Sweden)

    Xianlin Zhou

    2016-03-01

    Full Text Available The huge consumption of iron ores in China has attracted much attention to utilizing low grade complex iron resources, such as high-aluminum hematite-limonite ore, which is a refractory resource and difficult to upgrade by traditional physical concentration processes due to the superfine size and close dissemination of iron minerals with gangue minerals. An innovative technology for a high temperature reduction-magnetic separation process was studied to upgrade a high-aluminum iron ore assaying 41.92% Fetotal, 13.74% Al2O3 and 13.96% SiO2. The optimized results show that the final metal iron powder, assaying 90.46% Fetotal, was manufactured at an overall iron recovery of 90.25% under conditions as follows: balling the high aluminum iron ore with 15% coal blended and at 0.3 basicity, reducing the dried pellets at 1350 °C for 25 min with a total C/Fe mass ratio of 1.0, grinding the reduced pellets up to 95%, passing at 0.074 mm and magnetically separating the ground product in a Davis Tube at a 0.10-T magnetic field intensity. The metal iron powder can be used as the burden for an electric arc furnace (EAF. Meanwhile, the nonmagnetic tailing is suitable to produce ceramic, which mainly consists of anorthite and corundum. An efficient way has been found to utilize high-aluminum iron resources.

  2. Thickness dependence of the levitation performance of double-layer high-temperature superconductor bulks above a magnetic rail

    Science.gov (United States)

    Sun, R. X.; Zheng, J.; Liao, X. L.; Che, T.; Gou, Y. F.; He, D. B.; Deng, Z. G.

    2014-10-01

    A double-layer high-temperature superconductor (HTSC) arrangement was proposed and proved to be able to bring improvements to both levitation force and guidance force compared with present single-layer HTSC arrangement. To fully exploit the applied magnetic field by a magnetic rail, the thickness dependence of a double-layer HTSC arrangement on the levitation performance was further investigated in the paper. In this study, the lower-layer bulk was polished step by step to different thicknesses, and the upper-layer bulk with constant thickness was directly superimposed on the lower-layer one. The levitation force and the force relaxation of the double-layer HTSC arrangement were measured above a Halbach magnetic rail. Experimental result shows that a bigger levitation force and a less levitation force decay could be achieved by optimizing the thickness of the lower-layer bulk HTSC. This thickness optimization method could be applied together with former reported double-layer HTSC arrangement method with aligned growth sector boundaries pattern. This series of study on the optimized combination method do bring a significant improvement on the levitation performance of present HTS maglev systems.

  3. Recovery of Iron from Pyrite Cinder Containing Non-ferrous Metals Using High-Temperature Chloridizing-Reduction-Magnetic Separation

    Science.gov (United States)

    Chen, Dong; Guo, Hongwei; Xu, Jifang; Lv, Yanan; Xu, Zemin; Huo, Haijiang

    2017-01-01

    This study presents a new technique that uses high-temperature chloridizing -reduction-magnetic separation to recover iron from pyrite cinder containing non-ferrous metals. The effects of the reduction temperature, reduction time, and chlorinating agent dosage were investigated. The optimized process parameters were proposed as the following: CaCl2 dosage of 2 pct, chloridizing at 1398 K (1125 °C) for 10 minutes, reducing at 1323 K (1050 °C) for 80 minutes, grinding to a particle size of 78.8 pct less than 45 μm, and magnetic field intensity of 73 mT. Under the optimized conditions, the Cu, Pb, and Zn removal rates were 45.2, 99.2, and 89.1 pct, respectively. The iron content of the magnetic concentrate was 90.6 pct, and the iron recovery rate was 94.8 pct. Furthermore, the reduction behavior and separation mechanism were determined based on microstructure and phase change analyses using X-ray powder diffraction, scanning electron microscope, and optical microscopy.

  4. Analysis and Design Optimization of a Coaxial Surface-Mounted Permanent-Magnet Magnetic Gear

    Directory of Open Access Journals (Sweden)

    Xiaoxu Zhang

    2014-12-01

    Full Text Available This paper presents the analysis and design optimization of a coaxial surface-mounted permanent-magnet magnetic gear. The magnetic field distribution in the coaxial magnetic gear is calculated analytically in the polar coordinate system and then validated by the finite element method (FEM. The analytical field solution allows the prediction of the magnetic torque, which is formulated as a function of design parameters. The impacts of key design parameters on the torque capability are then studied and some significant observations are summarized. Furthermore, the particle swarm optimization (PSO algorithm is employed to optimize the studied magnetic gear. Given that the torque capability and material cost conflict with each other, both of them are set as the optimization objectives in this paper. Different weight factors may be chosen for the two objectives so that more attention can be placed on one or another. The results shows that the highest torque density of 157 kNm/m3 is achieved with the consideration focusing on the torque capability only, then the highest torque per permanent magnet (PM consumption could be improved to 145 Nm/kg by taking the material cost into account. By synthesizing the torque capability and material cost, a 124 kNm/m3 of torque density and a 128 Nm/kg of torque per PM consumption could be achieved simultaneously by the optimal design.

  5. Magnetic Field Analysis of Interior Composite-Rotor Controllable-Flux Permanent Magnet Synchronous Machine

    Institute of Scientific and Technical Information of China (English)

    CHEN Yiguang; PAN Wei; SHEN Yonghuan; TANG Renyuan

    2006-01-01

    Conventional permanent magnet synchronous machine(PMSM)has the problem of large stator copper loss and narrow speed range. To solve this problem, an interior composite-rotor controllable-flux PMSM adaptive to multi-polar is proposed. This machine has the characteristics of low stator copper loss and wide-speed operation. The half-radial-set and half-tangential-set permanent magnets(PMs)are NdFeB that has high remanent flux density and high coercive force. The tangential-set PMs are AlNiCo that has high remanent flux density and low coercive force. By applying the pulse of d-axis stator current id, the magnetized intensity and direction of AlNiCo can be controlled. The flux created by NdFeB is repelled to stator and air-gap PM-flux is intensified, or is partially bypassed by AlNiCo in the rotor, so the air-gap PM-flux is weakened. The internal magnetic field distribution in two ultra magnetized situations is analyzed by finite element method. The dimension of PMs and magnetic structure are demonstrated. Especially when the q-axis magnetic resistance is larger and the q-axis inductance is smaller, the result of flux-weakening is better and the influence of armature reaction on air-gap PM-flux is weakened.

  6. Simulation and experiments of stacks of high temperature superconducting coated conductors magnetized by pulsed field magnetization with multi-pulse technique

    Science.gov (United States)

    Zou, Shengnan; Zermeño, Víctor M. R.; Baskys, A.; Patel, A.; Grilli, Francesco; Glowacki, B. A.

    2017-01-01

    High temperature superconducting bulks or stacks of coated conductors (CCs) can be magnetized to become trapped field magnets (TFMs). The magnetic fields of such TFMs can break the limitation of conventional magnets (low cost. However, due to the heat generation during the magnetization, the trapped field and flux acquired by PFM usually cannot achieve the full potential of a sample (acquired by the field cooling or zero field cooling method). The multi-pulse technique was found to effectively improve the trapped field by PFM in practice. In this work, a systematic study on the PFM with successive pulses is presented. A 2D electromagnetic-thermal coupled model with comprehensive temperature dependent parameters is used to simulate a stack of CCs magnetized by successive magnetic pulses. An overall picture is built to show how the trapped field and flux evolve with different pulse sequences and the evolution patterns are analyzed. Based on the discussion, an operable magnetization strategy of PFM with successive pulses is suggested to provide more trapped field and flux. Finally, experimental results of a stack of CCs magnetized by typical pulse sequences are presented for demonstration.

  7. Evidence for single-chain magnet behavior in a Mn(III)-Ni(II) chain designed with high spin magnetic units: a route to high temperature metastable magnets.

    Science.gov (United States)

    Clérac, Rodolphe; Miyasaka, Hitoshi; Yamashita, Masahiro; Coulon, Claude

    2002-10-30

    . This result indicates the presence of a metastable state without magnetic long-range order. This material is the first experimental design of a heterometallic chain with ST = 3 magnetic units showing a "single-chain magnet" behavior predicted in 1963 by R. J. Glauber for an Ising one-dimensional system. This work opens new perspectives for one-dimensional systems to obtain high temperature metastable magnets by combining high spin magnetic units, strong interunit interactions, and uniaxial anisotropy.

  8. Rotatable Small Permanent Magnet Array for Ultra-Low Field Nuclear Magnetic Resonance Instrumentation: A Concept Study.

    Directory of Open Access Journals (Sweden)

    Michael W Vogel

    Full Text Available We studied the feasibility of generating the variable magnetic fields required for ultra-low field nuclear magnetic resonance relaxometry with dynamically adjustable permanent magnets. Our motivation was to substitute traditional electromagnets by distributed permanent magnets, increasing system portability.The finite element method (COMSOL® was employed for the numerical study of a small permanent magnet array to calculate achievable magnetic field strength, homogeneity, switching time and magnetic forces. A manually operated prototype was simulated and constructed to validate the numerical approach and to verify the generated magnetic field.A concentric small permanent magnet array can be used to generate strong sample pre-polarisation and variable measurement fields for ultra-low field relaxometry via simple prescribed magnet rotations. Using the array, it is possible to achieve a pre-polarisation field strength above 100 mT and variable measurement fields ranging from 20-50 μT with 200 ppm absolute field homogeneity within a field-of-view of 5 x 5 x 5 cubic centimetres.A dynamic small permanent magnet array can generate multiple highly homogeneous magnetic fields required in ultra-low field nuclear magnetic resonance (NMR and magnetic resonance imaging (MRI instruments. This design can significantly reduce the volume and energy requirements of traditional systems based on electromagnets, improving portability considerably.

  9. Electromagnetic Flux Analysis of Permanent Magnet Brushless DC Motor Using Magnet Software

    Directory of Open Access Journals (Sweden)

    G.R.Puttalakshmi

    2013-08-01

    Full Text Available Permanent Magnet Brushless DC (PMBLDC motors is emerging as a suitable motor for a number of drive applications in industrial and consumer products. Cogging torque is one of the important drawbacks of PMBLDC motor which results in shaft vibrations and noise. The focus of this work is to minimize the electromagnetic flux and cogging torque in PMBLDC by introducing structural design modifications. The performance of the machine is analyzed by varying the magnet pole shape, magnet pole width and by using magnetic material with different remenance value. For analyzing the performance of the machine, machine is modeled using Finite Element Analysis (FEA based software package Magnet. Cogging torque and average torque are taken as performance measures to determineoptimum pole shape and pole width.

  10. Radiation-induced magnetization reversal causing a large flux loss in undulator permanent magnets.

    Science.gov (United States)

    Bizen, Teruhiko; Kinjo, Ryota; Hasegawa, Teruaki; Kagamihata, Akihiro; Kida, Yuichiro; Seike, Takamitsu; Watanabe, Takahiro; Hara, Toru; Itoga, Toshiro; Asano, Yoshihiro; Tanaka, Takashi

    2016-11-29

    We report an unexpectedly large flux loss observed in permanent magnets in one of the undulators operated in SACLA, the x-ray free electron laser facility in Japan. Characterizations of individual magnets extracted from the relevant undulator have revealed that the flux loss was caused by a homogeneous magnetization reversal extending over a wide area, but not by demagnetization of individual magnets damaged by radiation. We show that the estimated flux-loss rate is much higher than what is reported in previous papers, and its distribution is much more localized to the upstream side. Results of numerical and experimental studies carried out to validate the magnetization reversal and quantify the flux loss are presented, together with possible countermeasures against rapid degradation of the undulator performance.

  11. Radiation-induced magnetization reversal causing a large flux loss in undulator permanent magnets

    Science.gov (United States)

    Bizen, Teruhiko; Kinjo, Ryota; Hasegawa, Teruaki; Kagamihata, Akihiro; Kida, Yuichiro; Seike, Takamitsu; Watanabe, Takahiro; Hara, Toru; Itoga, Toshiro; Asano, Yoshihiro; Tanaka, Takashi

    2016-11-01

    We report an unexpectedly large flux loss observed in permanent magnets in one of the undulators operated in SACLA, the x-ray free electron laser facility in Japan. Characterizations of individual magnets extracted from the relevant undulator have revealed that the flux loss was caused by a homogeneous magnetization reversal extending over a wide area, but not by demagnetization of individual magnets damaged by radiation. We show that the estimated flux-loss rate is much higher than what is reported in previous papers, and its distribution is much more localized to the upstream side. Results of numerical and experimental studies carried out to validate the magnetization reversal and quantify the flux loss are presented, together with possible countermeasures against rapid degradation of the undulator performance.

  12. A few simple classroom experiments with a permanent U-shaped magnet

    Science.gov (United States)

    Babović, Miloš; Babović, Vukota

    2017-01-01

    A few simple experiments in the magnetic field of a permanent U-shaped magnet are described. Among them, pin oscillations inside the magnet are particularly interesting. These easy to perform and amusing measurements can help pupils understand magnetic phenomena and mutually connect knowledge of various physics branches.

  13. Magnetic-Field-Induced Soft-Mode Quantum Phase Transition in the High-Temperature Superconductor La1.855Sr0.145CuO4

    DEFF Research Database (Denmark)

    Chang, J.; Christensen, Niels Bech; Niedermayer, C.

    2009-01-01

    Inelastic neutron-scattering experiments on the high-temperature superconductor La1.855Sr0.145CuO4 reveal a magnetic excitation gap Delta that decreases continuously upon application of a magnetic field perpendicular to the CuO2 planes. The gap vanishes at the critical field required to induce long...

  14. Field-induced interplanar magnetic correlations in the high-temperature superconductor La1.88Sr0.12CuO4

    DEFF Research Database (Denmark)

    Rømer, A. T.; Jensen, P.; Jacobsen, H.

    2015-01-01

    We present neutron-scattering studies of the interplanar magnetic correlations in the high-temperature superconductor La1.88Sr0.12CuO4 (Tc=27 K). The correlations are studied both in a magnetic field applied perpendicular to the CuO2 planes, and in zero field under different cooling conditions. We...

  15. Optimal current waveforms for brushless permanent magnet motors

    Science.gov (United States)

    Moehle, Nicholas; Boyd, Stephen

    2015-07-01

    In this paper, we give energy-optimal current waveforms for a permanent magnet synchronous motor that result in a desired average torque. Our formulation generalises previous work by including a general back-electromotive force (EMF) wave shape, voltage and current limits, an arbitrary phase winding connection, a simple eddy current loss model, and a trade-off between power loss and torque ripple. Determining the optimal current waveforms requires solving a small convex optimisation problem. We show how to use the alternating direction method of multipliers to find the optimal current in milliseconds or hundreds of microseconds, depending on the processor used, which allows the possibility of generating optimal waveforms in real time. This allows us to adapt in real time to changes in the operating requirements or in the model, such as a change in resistance with winding temperature, or even gross changes like the failure of one winding. Suboptimal waveforms are available in tens or hundreds of microseconds, allowing for quick response after abrupt changes in the desired torque. We demonstrate our approach on a simple numerical example, in which we give the optimal waveforms for a motor with a sinusoidal back-EMF, and for a motor with a more complicated, nonsinusoidal waveform, in both the constant-torque region and constant-power region.

  16. Permanent Magnet Synchronous Condenser with Solid State Excitation

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Ping; Muljadi, Eduard; Wu, Ziping; Gao, Wenzhong

    2015-10-05

    A synchronous condenser consists of a free-spinning wound-field synchronous generator and a field excitation controller. In this paper, we propose a synchronous generator that employs a permanent magnet synchronous generator (PMSG) instead of a wound-field machine. PMSGs have the advantages of higher efficiency and reliability. In the proposed configuration, the reactive power control is achieved by a voltage source converter connected in series with the PMSG and the grid. The converter varies the phase voltage of the PMSG so as to create the same effect of over or under excitation in a wound-field machine. The converter output voltage level controls the amount and the direction of the produced reactive power and the voltage's phase is kept in-phase with the grid voltage except a slight phase can be introduced so that some power can be drawn from the grid for maintaining the DC bus voltage level of the converter. Since the output voltage of the converter is only a fraction of the line voltage, its VA rating is only a fraction of the rating of the PMSG. The proposed scheme is shown to be effective by computer simulation.

  17. Design of High Performance Permanent-Magnet Synchronous Wind Generators

    Directory of Open Access Journals (Sweden)

    Chun-Yu Hsiao

    2014-11-01

    Full Text Available This paper is devoted to the analysis and design of high performance permanent-magnet synchronous wind generators (PSWGs. A systematic and sequential methodology for the design of PMSGs is proposed with a high performance wind generator as a design model. Aiming at high induced voltage, low harmonic distortion as well as high generator efficiency, optimal generator parameters such as pole-arc to pole-pitch ratio and stator-slot-shoes dimension, etc. are determined with the proposed technique using Maxwell 2-D, Matlab software and the Taguchi method. The proposed double three-phase and six-phase winding configurations, which consist of six windings in the stator, can provide evenly distributed current for versatile applications regarding the voltage and current demands for practical consideration. Specifically, windings are connected in series to increase the output voltage at low wind speed, and in parallel during high wind speed to generate electricity even when either one winding fails, thereby enhancing the reliability as well. A PMSG is designed and implemented based on the proposed method. When the simulation is performed with a 6 Ω load, the output power for the double three-phase winding and six-phase winding are correspondingly 10.64 and 11.13 kW. In addition, 24 Ω load experiments show that the efficiencies of double three-phase winding and six-phase winding are 96.56% and 98.54%, respectively, verifying the proposed high performance operation.

  18. Thermal analysis of high speed permanent magnetic generator

    Institute of Scientific and Technical Information of China (English)

    LI WeiLi; ZHANG XiaoChen; CHENG ShuKang; CAO JunCi; ZHANG YiHuang

    2012-01-01

    High-speed permanent magnetic generators (HSPMG) are common and important power generation equipments used in distributed generation systems.A 100 kW level HSPMG is investigated in this paper,and it is fluid-thermal coupling analyzed.The transient 2D electromagnetic field while machine is under rated operating is analyzed by using the time-stepping FEM,from which the electromagnetic performances and the loss distributions are obtained.Then,an analysis model for fluid-solid temperature field analysis is established.Taking losses as the distributed heat sources,the 3D thermal field is coupling calculated.The variations of heat transfer coefficient and temperature of fluid in stator grooves along the axial direction,as well as the whole region 3D temperature distribution in HSPMG are obtained.Then,considering the variations of heat sources distributions and heat transfer conditions,3D temperature fields of HSPMG operating under different speeds are calculated,and the influences of machine operating speed on the HSPMG thermal performance are studied,based on which,the functions of machine temperature with operating speed and stator windings resistance are proposed.The obtained conclusions may provide a useful reference for the design and research of HSPMG.

  19. Characterization of the ELIMED prototype permanent magnet quadrupole system

    Science.gov (United States)

    Russo, A. D.; Schillaci, F.; Pommarel, L.; Romano, F.; Amato, A.; Amico, A. G.; Calanna, A.; Cirrone, G. A. P.; Costa, M.; Cuttone, G.; Amato, C.; De Luca, G.; Flacco, F. A.; Gallo, G.; Giove, D.; Grmek, A.; La Rosa, G.; Leanza, R.; Maggiore, M.; Malka, V.; Milluzzo, G.; Petringa, G.; Pipek, J.; Scuderi, V.; Vauzour, B.; Zappalà, E.

    2017-01-01

    The system described in this work is meant to be a prototype of a more performing one that will be installed at ELI-Beamlines in Prague for the collection of ions produced after the interaction Laser-target, [1]. It has been realized by the researchers of INFN-LNS (Laboratori Nazionali del Sud of the Instituto Nazionale di Fisica Nucleare) and SIGMAPHI, a French company, using a system of Permanent Magnet Quadrupoles (PMQs), [2]. The final system that will be installed in Prague is designed for protons and carbons up to 60 MeV/u, around 10 times more than the energies involved in the present work. The prototype, shown in this work, has been tested in collaboration with the SAPHIR experimental facility group at LOA (Laboratoire d'Optique Appliqueé) in Paris using a 200 TW Ti:Sapphire laser system. The purpose of this work is to validate the design and the performances of this large and compact bore system and to characterize the beam produced after the interaction laser-target and its features. Moreover, the optics simulations have been compared with a real beam shape on a GAFChromic film. The procedure used during the experimental campaign and the most relevant results are reported here demonstrating a good agreement with the simulations and a good control on the beam optics.

  20. Research on an Improved Method for Permanent Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Yingpei Liu

    2014-01-01

    Full Text Available In permanent magnet synchronous motor (PMSM traditional vector control system, PI regulator is used in the speed loop, but it has some defects. An improved method of PMSM vector control is proposed in the paper. The active-disturbance rejection control (ADRC speed regulator is designed with the input signals of given speed and real speed and the output of given stator current q coordinate component. Then, in order to optimize ADRC controller, the least squares support vector machines (LSSVM optimal regression model is derived and successfully embedded in the ADRC controller. ADRC observation precision and dynamic response of the system are improved. The load disturbance effect on the system is reduced to a large extent. The system anti-interference ability is further improved. Finally, the current sensor CSNE151-100 is selected to sample PMSM stator currents. The voltage sensor JLBV1 is used to sample the stator voltage. The rotor speed of PMSM is measured by mechanical speed sensor, the type of which is BENTLY 330500. Experimental platform is constructed to verify the effectiveness of the proposed method.

  1. Permanent Magnet Synchronous Condenser with Solid State Excitation: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, P.; Muljadi, E.; Wu, Z.; Gao, W.

    2015-04-07

    A typical synchronous condenser (SC) consists of a free-spinning, wound-field synchronous generator and a field excitation controller. In this paper, we propose an SC that employs a permanent magnet synchronous generator (PMSG) instead of a wound-field machine. PMSGs have the advantages of higher efficiency and reliability. In the proposed configuration, the reactive power control is achieved by a voltage converter controller connected in series to the PMSG. The controller varies the phase voltage of the PMSG and creates the same effect on the reactive power flow as that of an over- or underexcited wound-field machine. The controller’s output voltage magnitude controls the amount of the reactive power produced by the SC. The phase of the controller’s output is kept within a small variation from the grid voltage phase. This small phase variation is introduced so that a small amount of power can be drawn from the grid into the controller to maintain its DC bus voltage. Because the output voltage of the controller is only a fraction of the line voltage, its VA rating is only a fraction of the rating of the PMSG. The proposed scheme is shown to be effective by computer simulations.

  2. Study on a magnetic spiral-type wireless capsule endoscope controlled by rotational external permanent magnet

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Bo, E-mail: yebo@hubu.edu.cn [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); School of Computer Science and Information Engineering, HuBei University, Wuhan 430062 (China); Zhang, Wei [Department of Mechanical Engineering, Hubei University of Automotive Technology, Shiyan 442002 (China); Sun, Zhen-jun [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); Guo, Lin [School of Computer Science and Information Engineering, HuBei University, Wuhan 430062 (China); Deng, Chao [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); Chen, Ya-qi [Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030 (China); Zhang, Hong-hai [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); Liu, Sheng [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China)

    2015-12-01

    In this paper, the authors propose rotating an external permanent magnet (EPM) to manipulate the synchronous rotation of a magnetic spiral-type wireless capsule endoscope (WCE), and the synchronous rotation of the WCE is converted to its translational motion in intestinal tract. In order to preliminarily verify the feasibility of this method, a handheld actuator (HA) controlled by micro controller unit, a magnetic spiral-type WCE and a bracket were fabricated, theoretical analysis and simulations about the control distance of this method were performed, and in ex-vivo tests were examined in porcine small intestine to verify the control distance and control performances of this method. It was demonstrated that this method showed good performances in controlling the translational motion of the magnetic spiral-type WCE, and this method has great potential to be used in clinical application. - Highlights: • A new magnetic control method for spiral-type wireless capsule endoscope is proposed. • Wireless capsule endoscope rotates synchronously with external permanent magnet. • The method controls the wireless capsule endoscope well in porcine small intestine. • Long control distance makes the method may be used in future medical application. • Experimental setup has great advantages: high cost performance and easy operation.

  3. Designing Model and Optimization of the Permanent Magnet for Joule Balance NIM-2

    CERN Document Server

    You, Qiang; Li, Zhengkun; Li, Shisong

    2016-01-01

    Permanent magnets with yokes are widely used in the watt and joule balances to measure the Planck constant for the forthcoming redefinition of the unit of mass, the kilogram. Recently, a permanent magnet system has been in consideration for a further practice of NIM-2, the generalized joule balance. In this paper, an analytical model to design the permanent magnet system is presented. The presented model can be solved to obtain the preliminary parameters and then is used as guidance for FEA software to optimize the parameters of such magnetic system. As an instance for the application of the designing model, the design of the permanent magnet system for NIM-2 is described and the special design of opening shape makes the misalignment of the top and middle yokes has little influence on the vertical component of the magnetic field.

  4. A magnetic probe equipped with small-tip permanent magnet for sentinel lymph node biopsy

    Science.gov (United States)

    Kaneko, Miki; Ohashi, Kaichi; Chikaki, Shinichi; Kuwahata, Akihiro; Shiozawa, Mikio; Kusakabe, Moriaki; Sekino, Masaki

    2017-05-01

    We previously developed a magnetic probe equipped with a ring-shaped permanent magnet for detecting magnetic nanoparticle tracer accumulating in the sentinel lymph nodes (SLNs). The magnetic probe enables us to identify SLNs objectively, without the risk of radiation exposure, unlike the conventional technique using dye and radioisotope. A technical challenge of the probe is to reduce the tip diameter of magnet to identify smaller SLNs. In this study, we optimized the size of smaller-tip magnet based on numerical analyses using the finite element method and evaluated the expected sensitivity. According to the analysis results, the optimum tip diameter and length of convex-shaped magnet were 16 mm and 12 mm, respectively. The experimental results showed that the sensitivity of the probe with smaller-tip magnet was comparable to the previous one. We successfully developed a smaller tip magnet, maintaining the sensitivity to magnetic nanoparticles. The proposed probe will be capable of identifying the location of SLNs more easily.

  5. Study on Transmission Torque Characteristics of a Surface-Permanent-Magnet-Type Magnetic Gear

    Science.gov (United States)

    Niguchi, Noboru; Hirata, Katsuhiro; Hayakawa, Yuichi

    Magnetic gears have some advantages such as low mechanical loss and maintenance-free operation that are not observed in conventional mechanical gears. In addition, magnetic gears have inherent overload protection. Therefore, magnetic gears are expected to be used in special applications; for example, they can be used in a joint of a humanoid robot. Recently, various types of new magnetic gears have been proposed. Among these new gears, a surface-permanent-magnet-type (SPM-type) magnetic gear employing harmonic magnetic flux has gained attention because of its high transmission torque density, though it has a complex structure with multipole magnets. Some studies on an SPM-type magnetic gear have been carried out, but there are few papers on cogging torque. This paper describes the transmission torque characteristics of an SPM-type magnetic gear. The operating principle and the transmission torque under synchronous operation are formulated in accordance with the gear ratio. High orders of the cogging torque are computed by employing the 3-D finite element method, and the validity of the analysis is verified by carrying out measurements on a prototype. Furthermore, a method for reducing the cogging torque is discussed.

  6. DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)

    DEFF Research Database (Denmark)

    Swierczynski, Dariusz; Kazmierkowski, Marian P.; Blaabjerg, Frede

    2002-01-01

    DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)......DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)...

  7. DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)

    DEFF Research Database (Denmark)

    Swierczynski, Dariusz; Kazmierkowski, Marian P.; Blaabjerg, Frede

    2002-01-01

    DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)......DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)...

  8. Permanent magnet motors from ABB eliminate gearboxes%ABB永磁电机在船舶上的应用

    Institute of Scientific and Technical Information of China (English)

    钱丽春

    2004-01-01

    Permanent magnet motor is synchronous and eliminates brushes, rotor windings ABB's permanent magnet motor is an AC synchronous motor. With such a motor, there is no rotor slip, which provides better accuracy than induct asynchronous, motors.

  9. Hydrodynamic Effects on Modeling and Control of a High Temperature Active Magnetic Bearing Pump with a Canned Rotor

    Energy Technology Data Exchange (ETDEWEB)

    Melin, Alexander M [ORNL; Kisner, Roger A [ORNL; Fugate, David L [ORNL; Holcomb, David Eugene [ORNL

    2015-01-01

    Embedding instrumentation and control Embedding instrumentation and control (I\\&C) at the component level in nuclear power plants can improve component performance, lifetime, and resilience by optimizing operation, reducing the constraints on physical design, and providing on-board prognostics and diagnostics. However, the extreme environments that many nuclear power plant components operate in makes embedding instrumentation and control at the component level difficult. Successfully utilizing embedded I\\&C requires developing a deep understanding of the system's dynamics and using that knowledge to overcome material and physical limitations imposed by the environment. In this paper, we will develop a coupled dynamic model of a high temperature (700 $^\\circ$C) canned rotor pump that incorporates rotordynamics, hydrodynamics, and active magnetic bearing dynamics. Then we will compare two control design methods, one that uses a simplified decoupled model of the system and another that utilizes the full coupled system model. It will be seen that utilizing all the available knowledge of the system dynamics in the controller design yield an order of magnitude improvement in the magnitude of the magnetic bearing response to disturbances at the same level of control effort, a large reduction in the settling time of the system, and a smoother control action.

  10. Negative and near zero refraction metamaterials based on permanent magnetic ferrites

    OpenAIRE

    Bi, Ke; Guo, Yunsheng; ZHOU, JI; Dong, Guoyan; Zhao, Hongjie; Zhao, Qian; Xiao, Zongqi; Liu, Xiaoming; Lan, Chuwen

    2014-01-01

    Ferrite metamaterials based on the negative permeability of ferromagnetic resonance in ferrites are of great interest. However, such metamaterials face a limitation that the ferromagnetic resonance can only take place while an external magnetic field applied. Here, we demonstrate a metamaterial based on permanent magnetic ferrite which exhibits not only negative refraction but also near zero refraction without applied magnetic field. The wedge-shaped and slab-shaped structures of permanent ma...

  11. Enduring Attraction: America’s Dependence On and Need to Secure Its Supply of Permanent Magnets

    Science.gov (United States)

    2012-10-01

    high technology businesses, especially the defense industry. They combine with other elements (specifically iron, boron, and cobalt ) to make...exceptional permanent magnets. Samarium- cobalt (SmCo) magnets have the highest known resistance to demagnetization.13 This capability, meaning the magnet...an equal mass of traditional ferrite magnet, an NdFeB magnet has over 10 times the magnetic energy product.14 Accordingly, a much smaller amount of

  12. In situ non-aqueous nucleation and growth of next generation rare-earth-free permanent magnets.

    Science.gov (United States)

    Yoon, Hyojung; Xu, Aoran; Sterbinsky, George E; Arena, Dario A; Wang, Ziying; Stephens, Peter W; Meng, Ying Shirley; Carroll, Kyler J

    2015-01-14

    Using a controllable wet chemical approach, the polyol process, we developed a cobalt carbide nanomagnet consisting of an assembly of Co2C and Co3C nanoparticles as an alternative to rare earth permanent magnets (PMs). The thermodynamically stable mixed phase cobalt carbide nanoparticles are shown to be acicular in morphology. Their exchange-coupled magnetic interaction possessing high maximum energy product of 20.7 kJ m(-3) and room temperature coercivity (2.9 kOe) has been confirmed through vibrating sample magnetometer (VSM) and first order reversal curves (FORCs). These metastable carbide nanoparticles offer improved magnetic properties compared to their pure bulk form. An understanding of the formation mechanism, using in situ time-resolved X-ray spectroscopy (TR-XAS), and the correlation between phase contributions to the properties are described in detail. Our strategy presents a controllable route to preparing the cobalt carbide nanomagnets, which could be potentially useful in permanent magnet clean energy applications. Additionally, the in situ apparatus offers a promising way to directly explore the effects of reaction variables for high-temperature wet chemical reactions.

  13. Permanent magnet electron beam ion source/trap systems with bakeable magnets for improved operation conditions.

    Science.gov (United States)

    Schmidt, M; Zschornack, G; Kentsch, U; Ritter, E

    2014-02-01

    The magnetic system of a Dresden electron beam ion source (EBIS) generating the necessary magnetic field with a new type of permanent magnet made of high energy density NdFeB-type material operable at temperatures above 100 °C has been investigated and tested. The employment of such kind of magnets provides simplified operation without the time-consuming installation and de-installation procedures of the magnets for the necessary baking of the ion source after commissioning and maintenance work. Furthermore, with the use of a new magnetization technique the geometrical filling factor of the magnetic Dresden EBIS design could be increased to a filling factor of 100% leading to an axial magnetic field strength of approximately 0.5 T exceeding the old design by 20%. Simulations using the finite element method software Field Precision and their results compared with measurements are presented as well. It could be shown that several baking cycles at temperatures higher than 100 °C did not change the magnetic properties of the setup.

  14. The Study on the Shape of 2-D Stator with Electromagnets and Permanent Magnets for 3-D Superconducting Actuator

    Science.gov (United States)

    Ozasa, S.; Kim, S. B.; Nakano, H.; Sawae, M.; Kobayashi, H.

    The electric device applications of a high temperature superconducting (HTS) bulk magnet having stable levitation and suspension properties due to their strong flux pinning force have been proposed and developed. We have been investigating the three-dimensional (3-D) superconducting actuator using HTS bulk to develop a non-contact transportation device. Probably, the cost of the manufactory will be increased to install the 2-D arranged electromagnets (EM) in a large area because many EMs are needed to cover the area. Therefore, we have been trying to find the method for reducing the number of EMs. In this study, all the EMs except for rotation were replaced in the 2-D arranged permanent magnets (PM), and gap length between PMs were experimentally investigated to improve the dynamic behavior of the mover and to reduce the cost of the manufacturing. As a result, we have succeeded in conveyance of the bulk and reduce the convergence time and maximum overshoot.

  15. Comparison and Analysis of Magnetic-Geared Permanent Magnet Electrical Machine at No-Load

    Directory of Open Access Journals (Sweden)

    Liu Xiping

    2014-12-01

    Full Text Available Magnetic-geared permanent magnet (MGPM electrical machine is a new type of machine by incorporating magnetic gear into PM electrical machine, and it may be in operation with low-speed, high-torque and direct-driven. In this paper, three types of MGPM machines are present, and a quantitative comparison among them is performed by finite element analysis (FEA. The magnetic field distribution, stable torque and back EMF are obtained at no-load. The results show that three types of MGPM machine are suitable for different application fields respectively according to their own advantages, such as high torque and back EMF, which form an important foundation for MGPM electrical machine research.

  16. Study on a magnetic spiral-type wireless capsule endoscope controlled by rotational external permanent magnet

    Science.gov (United States)

    Ye, Bo; Zhang, Wei; Sun, Zhen-jun; Guo, Lin; Deng, Chao; Chen, Ya-qi; Zhang, Hong-hai; Liu, Sheng

    2015-12-01

    In this paper, the authors propose rotating an external permanent magnet (EPM) to manipulate the synchronous rotation of a magnetic spiral-type wireless capsule endoscope (WCE), and the synchronous rotation of the WCE is converted to its translational motion in intestinal tract. In order to preliminarily verify the feasibility of this method, a handheld actuator (HA) controlled by micro controller unit, a magnetic spiral-type WCE and a bracket were fabricated, theoretical analysis and simulations about the control distance of this method were performed, and in ex-vivo tests were examined in porcine small intestine to verify the control distance and control performances of this method. It was demonstrated that this method showed good performances in controlling the translational motion of the magnetic spiral-type WCE, and this method has great potential to be used in clinical application.

  17. Radiofrequency hydrogen ion source with permanent magnets providing axial magnetic field.

    Science.gov (United States)

    Oikawa, Kohei; Saito, Yuta; Komizunai, Shota; Takahashi, Kazunori; Ando, Akira

    2014-02-01

    Uniform axial magnetic field of about 70 G is applied to a radiofrequency (rf) hydrogen ion source by arrays of permanent magnets. The plasma density and electron temperature downstream of the source and near the magnetic filter are compared with those in the previously described ion source, where the axial field has been applied by two solenoids. The source is operated at ∼350 kHz and above 10 kW rf power with a field-effect-transistor-based invertor power supply in 1.5 Pa hydrogen. The results show that the plasma density of ∼10(19) m(-3) near the source exit and ∼10(18) m(-3) near the magnetic filter can be obtained, which are higher than those with the solenoids.

  18. Study of metal magnetic memory (MMM) technique using permanently installed magnetic sensor arrays

    Science.gov (United States)

    Li, Zhichao; Dixon, Steve; Cawley, Peter; Jarvis, Rollo; Nagy, Peter B.

    2017-02-01

    The metal magnetic memory (MMM) effect has been reported to be a non-destructive testing technique capable of evaluating stress concentration and detecting defects in steel. This method has been shown to work well in some instances, but has failed in other trials. Its mechanism has been explained widely but the sensitivity to stress concentration has not been satisfactorily investigated. In this paper, both the normal and tangential components of the stress induced MMM signal were measured by two permanently installed magnetic sensor arrays on two types of notched L80 steel specimens. As expected, the results show that an externally applied magnetic field changes the magnetic field perturbation due to the notches linearly. Plastic deformation and residual stress around notches will increase the remnant flux leakage but the effects are small, which suggests that the MMM effect is very small in the material tested and that it will not be useful in practice.

  19. Radiofrequency hydrogen ion source with permanent magnets providing axial magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Oikawa, Kohei, E-mail: oikawa@ecei.tohoku.ac.jp; Saito, Yuta; Komizunai, Shota; Takahashi, Kazunori; Ando, Akira [Department of Electrical Engineering, Tohoku University, Sendai 980-8579 (Japan)

    2014-02-15

    Uniform axial magnetic field of about 70 G is applied to a radiofrequency (rf) hydrogen ion source by arrays of permanent magnets. The plasma density and electron temperature downstream of the source and near the magnetic filter are compared with those in the previously described ion source, where the axial field has been applied by two solenoids. The source is operated at ∼350 kHz and above 10 kW rf power with a field-effect-transistor-based invertor power supply in 1.5 Pa hydrogen. The results show that the plasma density of ∼10{sup 19} m{sup −3} near the source exit and ∼10{sup 18} m{sup −3} near the magnetic filter can be obtained, which are higher than those with the solenoids.

  20. A tubular hybrid Halbach/axially-magnetized permanent-magnet linear machine

    Directory of Open Access Journals (Sweden)

    Yi Sui

    2017-05-01

    Full Text Available A single-phase tubular permanent-magnet linear machine (PMLM with hybrid Halbach/axially-magnetized PM arrays is proposed for free-piston Stirling power generation system. Machine topology and operating principle are elaborately illustrated. With the sinusoidal speed characteristic of the free-piston Stirling engine considered, the proposed machine is designed and calculated by finite-element analysis (FEA. The main structural parameters, such as outer radius of the mover, radial length of both the axially-magnetized PMs and ferromagnetic poles, axial length of both the middle and end radially-magnetized PMs, etc., are optimized to improve both the force capability and power density. Compared with the conventional PMLMs, the proposed machine features high mass and volume power density, and has the advantages of simple control and low converter cost. The proposed machine topology is applicable to tubular PMLMs with any phases.

  1. A tubular hybrid Halbach/axially-magnetized permanent-magnet linear machine

    Science.gov (United States)

    Sui, Yi; Liu, Yong; Cheng, Luming; Liu, Jiaqi; Zheng, Ping

    2017-05-01

    A single-phase tubular permanent-magnet linear machine (PMLM) with hybrid Halbach/axially-magnetized PM arrays is proposed for free-piston Stirling power generation system. Machine topology and operating principle are elaborately illustrated. With the sinusoidal speed characteristic of the free-piston Stirling engine considered, the proposed machine is designed and calculated by finite-element analysis (FEA). The main structural parameters, such as outer radius of the mover, radial length of both the axially-magnetized PMs and ferromagnetic poles, axial length of both the middle and end radially-magnetized PMs, etc., are optimized to improve both the force capability and power density. Compared with the conventional PMLMs, the proposed machine features high mass and volume power density, and has the advantages of simple control and low converter cost. The proposed machine topology is applicable to tubular PMLMs with any phases.

  2. Optimal design method for magnetization directions of a permanent magnet array

    Science.gov (United States)

    Choi, Jae Seok; Yoo, Jeonghoon

    2010-08-01

    In many magnetic systems, the permanent magnet (PM) pattern has a great influence on their performance. This study proposes a systematic optimization method for designing discrete magnetization directions. While previous works have been mostly dependent on researchers' intuition, the developed method is systematic and can be applied to a two-dimensional PM-type eddy current brake model. The effectiveness of the method is confirmed, where the design's aim is to maximize the braking force on a moving conductor. The sensitivity analysis is accomplished by the adjoint variable method and the sequential linear programming is used as an optimizer. Several optimization results for various conditions through the proposed design method are compared to each other and the optimal magnet configuration for an eddy current brake is suggested.

  3. Permanent magnet motor drives with switched stator windings

    Energy Technology Data Exchange (ETDEWEB)

    Nipp, E.

    1999-06-01

    Permanent magnet (PM) motors are today regarded as an interesting solution for a wide range of inverter-fed variable-speed drives. The generally increased interest in these motors has led to many investigations on their feasibility for vehicle propulsion. Consequently, they are also of interest for traction applications which led to the research project that is presented in this thesis. The most important advantages that are expected in comparison to the state of the art asynchronous motors are lower losses and a higher torque density. Often the field weakening speed range is important, but difficult to obtain with PM machines because the inductance in the direction of the magnetization tends to be low. An alternative can be to switch different coils groups of the stator winding into different configurations. This is the central topic of this thesis. Various aspects of the design of PM motor drives are considered with special attention to the requirements for the application of the switched winding concept. The studies were thereby limited to the inner rotor, radial flux topology. It was found that two winding parts per phase, implying four different winding connections, is the only interesting solution. An advantage of switched windings is that the internal voltage of the machine will never exceed the maximum inverter output, which increases the operation safety. Furthermore the machine design can uncompromisingly be optimized for operation below base speed, which means low inductances implying a large air gap length and thick magnets. A problem with switched windings is that circulating currents can occur. To diminish them, a 2/3 magnet covering of the pole surface must be chosen in combination with a non-salient rotor. Moreover it was found that the eddy current losses in the magnets can reach non-negligible levels and must be considered when designing a drive system. The major drawback of switched stator windings is probably the occurrence of torque

  4. Design and Demonstration of a Test-Rig for Static Performance-Studies of Permanent Magnet Couplings

    DEFF Research Database (Denmark)

    Högberg, Stig; Jensen, Bogi Bech; Bendixen, Flemming Buus

    2013-01-01

    The design and construction of an easy-to-use test-rig for permanent magnet couplings is presented. Static torque of permanent magnet couplings as a function of angular displacement is measured of permanent magnet couplings through an semi-automated test system. The test-rig is capable of measuring...

  5. Performance of a Cylindrical Hall-Effect Thruster with Magnetic Field Generated by Permanent Magnets

    Science.gov (United States)

    Polzin, Kurt A.; Raitses, Yevgeny; Fisch, Nathaniel J.

    2008-01-01

    While Hall thrusters can operate at high efficiency at kW power levels, it is difficult to construct one that operates over a broad envelope down to 100W 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. An alternative approach is to employ a cylindrical Hall thruster (CHT) geometry. Laboratory model CHTs have operated at power levels ranging from the order of 50 Watts up to 1 kW. These thrusters exhibit performance characteristics which are comparable to conventional, annular Hall thrusters of similar size. Compared to the annular Hall thruster, the CHT has a lower insulator surface area to discharge chamber volume ratio. 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. This makes the CHT geometry promising for low-power applications. Recently, a CHT that uses permanent magnets to produce the magnetic field topology was tested. This thruster has the promise of reduced power consumption over previous CHT iterations that employed electromagnets. Data are presented for two purposes: to expose the effect different controllable parameters have on the discharge and to summarize performance measurements (thrust, Isp, efficiency) obtained using a thrust stand. These data are used to gain insight into the thruster's operation and to allow for quantitative comparisons between the permanent magnet CHT and the electromagnet CHT.

  6. Flat-type permanent magnet linear alternator: A suitable device for a free piston linear alternator

    Institute of Scientific and Technical Information of China (English)

    Qing-feng LI; Jin XIAO; Zhen HUANG

    2009-01-01

    We proposed the flat-type permanent magnet linear alternator (LA) for free piston linear alternators (FPLAs) instead of the tubular one. Using the finite element method (FEM), we compare these two kinds of LAs. The FEM result shows that the flat-type permanent magnet LA has higher efficiency and larger output specific power than the tubular one, therefore more suitable for FPLAs, and that the alternator design can be optimized with respect to the permanent magnet length as well as the air gap.

  7. Electro-magnetic properties and engineering applications of single-domain high temperature superconductor yttrium barium copper oxide

    Science.gov (United States)

    Qu, Dehui

    High temperature superconductors (HTS) exhibit a commonly known Meissner effect, which can cause a unusually strong magnetic repulsion. Using this effect, magnetic bearings have been constructed with 1000 times less friction than that of conventional bearings. The commercialization of the flywheel energy storage device (FESD) could mean cost-savings for the electric power industry. For instance, using a flywheel device, the energy can be generated most efficiently at a steady rate, and meet the high demand in peak daytime hours. Since the magnetic levitation using HTS involves very little friction, only about 0.1 percent of stored energy is lost per hour making electricity consumption most economic. As FESD is to be commercialized in the future, need for more expensive fossil fuel generating plants would be reduced or eliminated. In magnetic levitation using an anisotropic HTS such as YBa2Cu 3Ox, it has been reported that the levitation force is determined by sample geometry and flux pinning strength. Previous studies on critical current density and flux creep have indicated that crystal orientation should have a significant effect on levitation force due to superconducting anisotropy. The underline mechanisms governing the levitation force associated with superconducting anisotropy have not, however, been identified. Finding the crystal orientation dependence of the levitation force is not only of great interest to fundamental studies, but also important for industrial applications. For instance, the levitation force has been found to be one of the key parameters influencing the energy loss in flywheel energy storage. Enhancement of the levitation force has been the main goal in HTS materials development for magnetic bearings. The study of the relationship between levitation force and various materials parameters including crystal orientation, flux pinning strength, and geometry provide valuable information in further optimizing the materials performance in

  8. ADAPTIVE FLUX OBSERVER FOR PERMANENT MAGNET SYNCHRONOUS MOTORS

    Directory of Open Access Journals (Sweden)

    A. A. Bobtsov

    2015-01-01

    Full Text Available The paper deals with the observer design problem for a flux in permanent magnet synchronous motors. It is assumed that some electrical parameters such as resistance and inductance are known numbers. But the flux, the angle and the speed of the rotor are unmeasurable. The new robust approach to design an adaptive flux observer is proposed that guarantees globally boundedness of all signals and, moreover, exponential convergence to zero of observer error between the true flux value and an estimate obtained from the adaptive observer. The problem of an adaptive flux observer design has been solved with using the trigonometrical properties and linear filtering which ensures cancellation of unknown terms arisen after mathematical calculations. The key idea is the new parameterization of the dynamical model containing unknown parameters and depending on measurable current and voltage in the motor. By applying the Pythagorean trigonometric identity the linear equation has found that does not contain any functions depending on angle or angular velocity of the rotor. Using dynamical first-order filters the standard regression model is obtained that consists of unknown constant parameters and measurable functions of time. Then the gradient-like estimator is designed to reconstruct unknown parameters, and it guarantees boundedness of all signals in the system. The proposition is proved that if the regressor satisfies the persistent excitation condition, meaning the “frequency-rich” signal, then all errors in observer exponentially converges to zero. It is shown that observer error for the flux explicitly depends on estimator errors. Exponential convergence of parameter estimation errors to zero yields exponential convergence of the flux observer error to zero. The numerical example is considered.

  9. A Steel Wire Stress Measuring Sensor Based on the Static Magnetization by Permanent Magnets.

    Science.gov (United States)

    Deng, Dongge; Wu, Xinjun; Zuo, Su

    2016-10-06

    A new stress measuring sensor is proposed to evaluate the axial stress in steel wires. Without using excitation and induction coils, the sensor mainly consists of a static magnetization unit made of permanent magnets and a magnetic field measurement unit containing Hall element arrays. Firstly, the principle is illustrated in detail. Under the excitation of the magnetization unit, a spatially varying magnetized region in the steel wire is utilized as the measurement region. Radial and axial magnetic flux densities at different lift-offs in this region are measured by the measurement unit to calculate the differential permeability curve and magnetization curve. Feature parameters extracted from the curves are used to evaluate the axial stress. Secondly, the special stress sensor for Φ5 and Φ7 steel wires is developed accordingly. At last, the performance of the sensor is tested experimentally. Experimental results show that the sensor can measure the magnetization curve accurately with the error in the range of ±6%. Furthermore, the obtained differential permeability at working points 1200 A/m and 10000 A/m change almost linearly with the stress in steel wires, the goodness of linear fits are all higher than 0.987. Thus, the proposed steel wire stress measuring sensor is feasible.

  10. A Steel Wire Stress Measuring Sensor Based on the Static Magnetization by Permanent Magnets

    Directory of Open Access Journals (Sweden)

    Dongge Deng

    2016-10-01

    Full Text Available A new stress measuring sensor is proposed to evaluate the axial stress in steel wires. Without using excitation and induction coils, the sensor mainly consists of a static magnetization unit made of permanent magnets and a magnetic field measurement unit containing Hall element arrays. Firstly, the principle is illustrated in detail. Under the excitation of the magnetization unit, a spatially varying magnetized region in the steel wire is utilized as the measurement region. Radial and axial magnetic flux densities at different lift-offs in this region are measured by the measurement unit to calculate the differential permeability curve and magnetization curve. Feature parameters extracted from the curves are used to evaluate the axial stress. Secondly, the special stress sensor for Φ5 and Φ7 steel wires is developed accordingly. At last, the performance of the sensor is tested experimentally. Experimental results show that the sensor can measure the magnetization curve accurately with the error in the range of ±6%. Furthermore, the obtained differential permeability at working points 1200 A/m and 10000 A/m change almost linearly with the stress in steel wires, the goodness of linear fits are all higher than 0.987. Thus, the proposed steel wire stress measuring sensor is feasible.

  11. Slot-Antenna/Permanent-Magnet Device for Generating Plasma

    Science.gov (United States)

    Foster, John E.

    2007-01-01

    A device that includes a rectangular-waveguide/slot-antenna structure and permanent magnets has been devised as a means of generating a substantially uniform plasma over a relatively large area, using relatively low input power and a low gas flow rate. The device utilizes electron cyclotron resonance (ECR) excited by microwave power to efficiently generate plasma in a manner that is completely electrodeless in the sense that, in principle, there is no electrical contact between the plasma and the antenna. Plasmas generated by devices like this one are suitable for use as sources of ions and/or electrons for diverse material-processing applications (e.g., etching or deposition) and for ion thrusters. The absence of plasma/electrode contact essentially prevents plasma-induced erosion of the antenna, thereby also helping to minimize contamination of the plasma and of objects exposed to the plasma. Consequently, the operational lifetime of the rectangular-waveguide/ slot-antenna structure is long and the lifetime of the plasma source is limited by the lifetime of the associated charged-particle-extraction grid (if used) or the lifetime of the microwave power source. The device includes a series of matched radiating slot pairs that are distributed along the length of a plasma-source discharge chamber (see figure). This arrangement enables the production of plasma in a distributed fashion, thereby giving rise to a uniform plasma profile. A uniform plasma profile is necessary for uniformity in any electron- or ion-extraction electrostatic optics. The slotted configuration of the waveguide/ antenna structure makes the device scalable to larger areas and higher powers. All that is needed for scaling up is the attachment of additional matched radiating slots along the length of the discharge chamber. If it is desired to make the power per slot remain constant in scaling up, then the input microwave power must be increased accordingly. Unlike in prior ECR microwave plasma

  12. Analysis and Design of Double-sided Air core Linear Servo Motor with Trapezoidal Permanent Magnets

    DEFF Research Database (Denmark)

    Zhang, Yuqiu; Yang, Zilong; Yu, Minghu;

    2011-01-01

    In order to reduce the thrust ripple of linear servo system, a double-sided air core permanent magnet linear servo motor with trapezoidal shape permanent magnets (TDAPMLSM) is proposed in this paper. An analytical model of the motor for predicting the magnetic field in the air-gap at no......-load is introduced. This model is derived based on the equivalent magnetization intensity method, and its accuracy is validated by using the results obtained from the finite-element method. The key dimensions that affect the air-gap magnetic field are analyzed based on the analytical model, and the design...

  13. Fabrication of bulk nanostructured permanent magnets with high energy density: challenges and approaches.

    Science.gov (United States)

    Yue, Ming; Zhang, Xiangyi; Liu, J Ping

    2017-03-06

    Nanostructured permanent magnetic materials, including exchange-coupled nanocomposite permanent magnets, are considered as the next generation of high-strength magnets for future applications in energy-saving and renewable energy technologies. However, fabrication of bulk nanostructured magnets remains very challenging because conventional compaction and sintering techniques cannot be used for nanostructured bulk material processing. In this paper we review recent efforts at producing bulk nanostructured single-phase and composite magnetic materials with emphasis on grain size control, anisotropy generation and interface modification.

  14. Use of Permanent Magnets in Electromagnetic Facilities for the Treatment of Aluminum Alloys

    Science.gov (United States)

    Beinerts, Toms; Bojarevičs, Andris; Bucenieks, Imants; Gelfgat, Yuri; Kaldre, Imants

    2016-06-01

    The possibility of applying the electromagnetic induction pump with permanent magnets for the transportation and stirring of aluminum melts in metallurgical furnaces is investigated. The electromagnetic and hydraulic characteristics of the pump have been investigated theoretically and experimentally with regard to its position in the furnace. The results of the experiments performed with a model in a eutectic InGaSn melt are in good agreement with the calculation data. Extrapolation of the experimental results on the physical characteristics of aluminum melts allows recommending such pumps for contactless control of motion and heat/mass transfer in aluminum melts in different technological processes. A high temperature and the aggressive properties of aluminum alloys make it complicated to use different mechanical devices to solve technological problems, such as liquid metal transportation, dosing, stirring, etc. In this case, any device units or elements moving in or contacting with the melt suffer from corrosion polluting the melt. Therefore, of more importance and topicality are contactless electromagnetic methods for processing of molten metals.

  15. Magnetic Field Equivalent Current Analysis-Based Radial Force Control for Bearingless Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Huangqiu Zhu

    2015-05-01

    Full Text Available Bearingless permanent magnet synchronous motors (BPMSMs, with all advantages of permanent magnet motors (PMSMs and magnetic bearings, have become an important research direction in the bearingless motor field. To realize a stable suspension for the BPMSM, accurate decoupling control between the electromagnetic torque and radial suspension force is indispensable. In this paper, a concise and reliable analysis method based on a magnetic field equivalent current is presented. By this analysis method, the operation principle is analyzed theoretically, and the necessary conditions to produce a stable radial suspension force are confirmed. In addition, mathematical models of the torque and radial suspension force are established which is verified by the finite element analysis (FEA software ANSYS. Finally, an experimental prototype of a 2-4 poles surface-mounted BPMSM is tested with the customized control strategy. The simulation and experimental results have shown that the motor has good rotation and suspension performance, and validated the accuracy of the proposed analysis method and the feasibility of the control strategy.

  16. Magnetic Forces Investigation of Bulk HTS over Permanent Magnetic Guideway under Different Lateral Offset with 3D-Model Numerical Method

    Directory of Open Access Journals (Sweden)

    Yiyun Lu

    2012-01-01

    Full Text Available Magnetic forces of a cylinder shape bulk high-temperature superconductor (HTS over a permanent magnet guideway (PMG are studied mathematically. One cylindrical bulk HTS with a diameter of 30 mm and 15 mm in height is used. Two types of PMG are employed for external magnetic fields consideration. The relationship of magnetic forces of bulk HTS under different lateral offsets over PMG is studied with 3D-model finite element method (FEM. The calculation results show that the maximum magnetic levitation force of bulk HTS over PMG is tightly related to the applied magnetic field distribution. For the symmetrical PMG, the maximum magnetic levitation force decreases linearly with the increase of lateral offset of the bulk sample. For the Halbach PMG, when lateral offset changes from 0 mm to 25 mm, the maximum magnetic levitation force increases with the increase of lateral offset of the bulk HTS. When the lateral offset exceeds the center of the Halbach by 25 mm, the maximum levitation force decreases rapidly with the increase of the lateral offset of the bulk sample.

  17. Large output-power, low-speed permanent magnet synchronous motor designs for ship propulsion drive

    Energy Technology Data Exchange (ETDEWEB)

    Rosu, M.

    2001-07-01

    Over the last decade, serious development has taken place in electric motor technology, and its impact is being felt in the shipbuilding community. This development has brought about a new generation of compact, high efficiency electrical machines. High performance, lightweight permanent magnet motors and generators have been developed for a wide range of applications including vehicle propulsion, power generation, pump and compressor drives. These machines combine the advances in magnetic materials and electronic design to provide shipbuilders new options for weight, energy and cost reduction. Permanent magnet machines were built in many different configurations and power classes, ranging from a few hundred watts to multi-megawatts for ship propulsion. Permanent magnet motors and generators for marine use were constructed and tested, all of these machines providing the same outstanding torque and power density. The basic electromagnetic, thermal and mechanical design approaches were established and tested in small prototype machines, the development of larger machines constituting the engineering later in the design process. The goal of this research work is to find an optimum solution in terms of design and suitability of a low-speed and high-power permanent magnet motor for ship propulsion drive. In this work, the study-case analyses are limited to the electromagnetic part of the motor. Two types of radial flux permanent magnet synchronous motors are designed and optimised to meet the propulsion requirements. The first motor has the permanent magnets mounted on the surface of the rotor while the second motor has the permanent magnets mounted on the rotor surface and covered by laminated pole shoes. In their construction, high-energy NdFeB permanent magnets were chosen. These magnetic materials provide a sufficient airgap magnetic flux density with a low volume of material. Moreover, the NdFeB permanent magnets are endowed with high coercivity. As an immediate

  18. Design and analysis of a novel inset permanent magnet synchronous motor

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, C.C. [Department of Electrical Enginering, Feng Chia University, 100 Wenhua Road, Seatwen, Taichung 407, Taiwan (China)], E-mail: cchwang@fcu.edu.tw; Liu, C.-T. [Department of Electrical Enginering, National Sun Yat-sen University, 70 Lien-Hai Road, Kaohsiung 804, Taiwan (China); Teng, C.C. [Department of Electrical Enginering, Feng Chia University, 100 Wenhua Road, Seatwen, Taichung 407, Taiwan (China)

    2008-07-15

    This paper presents the design of a permanent magnet (PM) synchronous motor with the magnets laid flush in slots let into the rotor surface, called inset magnet rotor. The finite element field analysis coupled with the drive circuit equations are briefly discussed for obtaining the motor performance. Experimental results obtained are in good agreement with the finite element analysis.

  19. Transformation Temperatures, Shape Memory and Magnetic Properties of Hafnium Modified Ti-Ta Based High Temperature Shape Memory Alloys

    Science.gov (United States)

    Khan, W. Q.; Wang, Q.; Jin, X.

    2017-02-01

    In this study the modification effect of Hf content on the shape memory properties and magnetic permeability of a 75.5-77Ti-20Ta-3-4.5Hf alloy system has been systematically studied by DSC, three-point bend test, vector network analyzer and XRD. The martensitic transformation temperature, heat of reaction and recovery strain increases with the increase of hafnium and tantalum content. A stable high temperature shape memory effect was observed (Ms = 385-390 °C) during the two thermal cycles between 20 °C and 725 °C. Transformation temperatures and heats of reaction were determined by DSC measurements. Recovery strain was determined by three-point bend testing. Also an alloy, 70Ti-26Ta-4Hf, with higher tantalum content was produced to observe the effect of Ta on the shape memory properties. Permeability increases gradually from 1.671 to 1.919 with increasing content of hafnium modification and remains stable in the frequency range of 450 MHz to 1 GHz.

  20. A Novel Integral 5-DOFs Hybrid Magnetic Bearing with One Permanent Magnet Ring Used for Turboexpander

    Directory of Open Access Journals (Sweden)

    Bangcheng Han

    2014-01-01

    Full Text Available We propose a novel combined five-degrees-of-freedom (5-DOFs hybrid magnetic bearing (HMB with only one permanent magnet ring (PMR used for turboexpanders. It has two radial magnetic bearing (RMB units; each has four poles and one thrust magnetic bearing (TMB to control 5-DOFs. Based on one PMR, the bias flux of the two radial magnetic bearing units and the one thrust magnetic bearing unit is constructed. As a result, ultra-high-speed, lower power loss, small size, and low cost can be achieved. Furthermore, the equivalent magnetic circuit method and 3D finite element method (FEM are used to model and analyze the combined 5-DOFs HMB. The force-current, force-position, torque-coil currents, the torque-angle position, and the stiffness models of the combined 5-DOFs HMB are given. Moreover, its coupling problems between the RMB units and the AMB unit are also proposed in this paper. An example is given to clarify the mathematical models and the coupling problems, and the linearized models are proposed for the follow-up controller design.

  1. Prospects for Non-Rare Earth Permanent Magnets for Traction Motors and Generators

    Science.gov (United States)

    Kramer, M. J.; McCallum, R. W.; Anderson, I. A.; Constantinides, S.

    2012-07-01

    With the advent of high-flux density permanent magnets based on rare earth elements such as neodymium (Nd) in the 1980s, permanent magnet-based electric machines had a clear performance and cost advantage over induction machines when weight and size were factors such as in hybrid electric vehicles and wind turbines. However, the advantages of the permanent magnet-based electric machines may be overshadowed by supply constraints and high prices of their key constituents, rare earth elements, which have seen nearly a 10-fold increase in price in the last 5 years and the imposition of export limits by the major producing country, China, since 2010. We outline the challenges, prospects, and pitfalls for several potential alloys that could replace Nd-based permanent magnets with more abundant and less strategically important elements.

  2. [Mechanical Shimming Method and Implementation for Permanent Magnet of MRI System].

    Science.gov (United States)

    Xue, Tingqiang; Chen, Jinjun

    2015-03-01

    A mechanical shimming method and device for permanent magnet of MRI system has been developed to meet its stringent homogeneity requirement without time-consuming passive shimming on site, installation and adjustment efficiency has been increased.

  3. Motor Integrated Permanent Magnet Gear with a Wide Torque-Speed Range

    DEFF Research Database (Denmark)

    Rasmussen, Peter Omand; Matzen, Torben N.; Jahns, T. M.

    2009-01-01

    This paper present a new motor integrated permanent magnet gear with a wide torque-speed range. In the paper a 35 kW permanent magnet motor with a base speed of 4000 rpm and a top speed of 14000 rpm is integrated into a permanent magnetic gear with a gearing ratio of 8.67. The design process...... of the combined unit is described together with a description of the construction of the part for a test model. The unit is unique in the sense that it has superior traction characteristics and a torque density of 130 Nm/l which is more 1.5 times of other reported motor integrated permanent magnet gears. The unit...... may be useful as a direct drive wheel motor for EV's and no liquid cooling system is required....

  4. Damage Analysis of Internal Faults in Flux Concentrating Permanent Magnet Motors

    Science.gov (United States)

    1994-06-01

    6 1.1 Ship Propulsion Systems...11 1.4 Faults in Permanent Magnet Ship Propulsion Motors...124 5 Chapter 1. Introduction The use of electric ship propulsion offers significant advantages in ship design

  5. Multimodel Modeling and Predictive Control for Direct-Drive Wind Turbine with Permanent Magnet Synchronous Generator

    OpenAIRE

    Lei Wang; Tao Shen; Chen Chen

    2014-01-01

    The safety and reliability of the wind turbines wholly depend on the completeness and reliability of the control system which is an important problem for the validity of the wind energy conversion systems (WECSs). A method based on multimodel modeling and predictive control is proposed for the optimal operation of direct-drive wind turbine with permanent magnet synchronous generator in this paper. In this strategy, wind turbine with direct-drive permanent magnet synchronous generator is model...

  6. Multimodel Modeling and Predictive Control for Direct-Drive Wind Turbine with Permanent Magnet Synchronous Generator

    OpenAIRE

    Lei Wang; Tao Shen; Chen Chen

    2014-01-01

    The safety and reliability of the wind turbines wholly depend on the completeness and reliability of the control system which is an important problem for the validity of the wind energy conversion systems (WECSs). A method based on multimodel modeling and predictive control is proposed for the optimal operation of direct-drive wind turbine with permanent magnet synchronous generator in this paper. In this strategy, wind turbine with direct-drive permanent magnet synchronous generator is model...

  7. Finite-Time Chaos Control of a Complex Permanent Magnet Synchronous Motor System

    Directory of Open Access Journals (Sweden)

    Xiaobing Zhou

    2014-01-01

    Full Text Available This paper investigates the finite-time chaos control of a permanent magnet synchronous motor system with complex variables. Based on the finite-time stability theory, two control strategies are proposed to realize stabilization of the complex permanent magnet synchronous motor system in a finite time. Two numerical simulations have been conducted to demonstrate the validity and feasibility of the theoretical analysis.

  8. Influence of the magnetic field orientation on the mixed state properties of high temperature superconductors: an ac shielding study

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, B

    1999-07-01

    This work deals with the influence of the orientation of an applied static magnetic field on the mixed state properties of high temperature superconducting cuprates. The mixed state is characterized by the presence of vortices (quanta of magnetic flux). Their properties have been tested via the dynamic approach of the shielding of an ac magnetic field. In pristine Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} crystals the first order transition of the vortex system from an ordered to a disordered state has been studied. It has been found that in the material the transition is mainly determined by the component of the field perpendicular to the superconducting copper oxide layers. However, the value of this component at the transition diminishes with the increase of the field component parallel to the layers. This is explained by the decrease of the Josephson coupling between 2D vortices in neighbouring planes in the presence of a parallel component. In heavy ion irradiated Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} the subject under investigation has been the pinning of the vortices by the irradiation tracks. These defects push the irreversibility line towards higher fields. In the field range that has become irreversible after irradiation pinning by columnar defects is anisotropic. This anisotropy in pinning indicates that a coupling exists between the 2D vortices that form a vortex line, in contrast to the behaviour in the pristine material in the same field range. HgBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 8} with columnar defects shows essentially the same behaviour as Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, the differences being well explained by the lower anisotropy of HgBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 8} which leads to a more linear character of the vortices. Finally, it has been shown that in pristine Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} the concentration of the vortices in the center of the sample is explained by the surface barrier alone. (author)

  9. Concentrated Windings in Compact Permanent Magnet Synchronous Generators: Managing Efficiency

    Directory of Open Access Journals (Sweden)

    Olivier Barré

    2016-01-01

    Full Text Available In electric power generation, customers want generators with high efficiency. Nowadays, modern turbo-generators have efficiencies greater than 98%. Although this amount should not be obtained for all kind of machines, efficiency will remain one of the main parameters for customer choice. Efficiency is also linked to the life of the machine: the higher the efficiency is, the longer the machine’s lifetime. During the past decade, new forms of energy production have appeared and generators have been developed to fit well into this market. For example, wind generators evolved towards permanent magnet generators having high polarity and running at low speed. Nevertheless, their structure is not fixed. An industrial company has built a prototype of such a generator which uses fractional-slot concentrated-windings (FSCW. This kind of winding is not the structure used by default in such electrical machines. Another field of interest is in autonomous generators which can be used on boats. Even if everyone has in mind large merchant ships, we must not forget smaller ships, such as fishing boats and short-range cruise ships, which spend the most of their time near the coast. This kind of ship does nothave large areas for installing the electric generation or the electric propulsion. It is the reason why, in this article, we focus on the efficiency of machines using fractional-slot concentrated-windings. In many publications which compare performances between distributed and concentrated windings, the result is almost the same. The efficiency of FSCW is not as high as the efficiency associated to the machines which are using distributed windings. Design methods have to be redrawn to integrate, as soon as possible, the loss mitigation in order to provide the best efficiency in power conversion. The following discussion, step by step, introduces the loss mitigation in every part of a machine using FSCW. To close the discussion, a design is produced and it

  10. Development of High-Field Permanent Magnetic Circuits for NMRI/MRI and Imaging on Mice

    Directory of Open Access Journals (Sweden)

    Guangxin Wang

    2016-01-01

    Full Text Available The high-field permanent magnetic circuits of 1.2 T and 1.5 T with novel magnetic focusing and curved-surface correction are developed. The permanent magnetic circuit comprises a magnetic yoke, main magnetic steel, nonspherical curved-surface magnetic poles, plugging magnetic steel, and side magnetic steel. In this work, a novel shimming method is proposed for the effective correction of base magnetic field (B0 inhomogeneities, which is based on passive shimming on the telescope aspheric cutting, grinding, and fine processing technology of the nonspherical curved-surface magnetic poles and active shimming adding higher-order gradient coils. Meanwhile, the magnetic resonance imaging dedicated alloy with high-saturation magnetic field induction intensity and high electrical resistivity is developed, and nonspherical curved-surface magnetic poles which are made of the dedicated alloy have very good anti-eddy-current effect. In addition, the large temperature coefficient problem of permanent magnet can be effectively controlled by using a high quality temperature controller and deuterium external locking technique. Combining our patents such as gradient coil, RF coil, and integration computer software, two kinds of small animal Micro-MRI instruments are developed, by which the high quality MRI images of mice were obtained.

  11. Design improvement of permanent magnet flux switching motor with dual rotor structure

    Science.gov (United States)

    Soomro, H. A.; Sulaiman, E.; Kumar, R.; Rahim, N. S.

    2017-08-01

    This paper presents design enhancement to reduce permanent magnet (PM) volume for 7S-6P-7S dual rotor permanent magnet flux-switching machines (DRPMFSM) for electric vehicle application. In recent years, Permanent magnet flux switching (PMFS) motor and a new member of brushless permanent magnet machine are prominently used for the electric vehicle. Though, more volume of Rare-Earth Permanent Magnet (REPM) is used to increase the cost and weight of these motors. Thus, to overcome the issue, new configuration of 7S-6P- 7S dual rotor permanent magnet flux-switching machine (DRPMFSM) has been proposed and investigated in this paper. Initially proposed 7S-6P-7S DRPMFSM has been optimized using “deterministic optimization” to reduce the volume of PM and to attain optimum performances. In addition, the performances of initial and optimized DRPMFSM have been compared such that back-emf, cogging torque, average torque, torque and power vs speed performances, losses and efficiency have been analysed by 2D-finite element analysis (FEA) using the JMAG- Designer software ver. 14.1. Consequently, the final design 7S-6P-7S DRPMFSM has achieved the efficiency of 83.91% at reduced PM volume than initial design to confirm the better efficient motor for HEVs applications.

  12. Influence of different rotor magnetic circuit structure on the performance of permanent magnet synchronous motor

    Directory of Open Access Journals (Sweden)

    Qiu Hongbo

    2017-09-01

    Full Text Available In order to compare the performance difference of the permanent magnet synchronous motors (PMSM with different rotor structure, two kinds of rotor magnetic circuit structure with surface-mounted radial excitation and tangential excitation are designed respectively. By comparing and analyzing the results, the difference of the motor performance was determined. Firstly, based on the finite element method (FEM, the motor electromagnetic field performance was studied, and the magnetic field distribution of the different magnetic circuit structure was obtained. The influence mechanism of the different magnetic circuit structure on the air gap flux density was obtained by using the Fourier theory. Secondly, the cogging torque, output torque and overload capacity of the PMSM with different rotor structure were studied. The effect mechanism of the different rotor structure on the motor output property difference was obtained. The motor prototype with two kinds of rotor structure was manufactured, and the experimental study was carried out. By comparing the experimental data and simulation data, the correctness of the research is verified. This paper lays a foundation for the research on the performance of the PMSM with different magnetic circuit structure.

  13. A Study on Magnetic Decoupling of Compound-Structure Permanent-Magnet Motor for HEVs Application

    Directory of Open Access Journals (Sweden)

    Qiwei Xu

    2016-10-01

    Full Text Available The compound-structure permanent-magnet (CSPM motor is used for an electrical continuously-variable transmission (E-CVT in a hybrid electric vehicle (HEV. It can make the internal combustion engine (ICE independent of the road loads and run in the high efficiency area to improve the fuel economy and reduce the emissions. This paper studies the magnetic coupling of a new type of CSPM motor used in HEVs. Firstly, through the analysis of the parameter matching with CSPM in the HEV, we receive the same dynamic properties’ design parameters between the CSPM motor and the THS (Toyota Hybrid System of the Toyota Prius. Next, we establish the equivalent magnetic circuit model of the overall and the secondary model considering the tangential and radial flux distribution in the outer rotor of the CSPM motor. Based on these two models, we explore the internal magnetic coupling rule of the CSPM motor. Finally, finite element method analysis in 2D-ansoft is used to analyze the magnetic field distribution of the CSPM motor in different operation modes. By the result of the finite element method analysis, the internal magnetic decoupling scheme is put forward, laying the theoretical foundation for the further application of the CSPM motor in HEVs.

  14. Piezoelectric response of a PZT thin film to magnetic fields from permanent magnet and coil combination

    Science.gov (United States)

    Guiffard, B.; Seveno, R.

    2015-01-01

    In this study, we report the magnetically induced electric field E 3 in Pb(Zr0.57Ti0.43)O3 (PZT) thin films, when they are subjected to both dynamic magnetic induction (magnitude B ac at 45 kHz) and static magnetic induction ( B dc) generated by a coil and a single permanent magnet, respectively. It is found that highest sensitivity to B dc——is achieved for the thin film with largest effective electrode. This magnetoelectric (ME) effect is interpreted in terms of coupling between eddy current-induced Lorentz forces (stress) in the electrodes of PZT and piezoelectricity. Such coupling was evidenced by convenient modelling of experimental variations of electric field magnitude with both B ac and B dc induction magnitudes, providing imperfect open circuit condition was considered. Phase angle of E 3 versus B dc could also be modelled. At last, the results show that similar to multilayered piezoelectric-magnetostrictive composite film, a PZT thin film made with a simple manufacturing process can behave as a static or dynamic magnetic field sensor. In this latter case, a large ME voltage coefficient of under B dc = 0.3 T was found. All these results may provide promising low-cost magnetic energy harvesting applications with microsized systems.

  15. Permanent magnetism in phosphine- and chlorine-capped gold: from clusters to nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Marquez, Miguel A., E-mail: miguel.angel@icmse.csic.es; Guerrero, Estefania; Fernandez, Asuncion [Instituto de Ciencia de Materiales de Sevilla (CSIC-US) (Spain); Crespo, Patricia; Hernando, Antonio [Instituto de Magnetismo Aplicado (UCM-ADIF-CSIC) (Spain); Lucena, Raquel; Conesa, Jose C. [Instituto de Catalisis y Petroleoquimica (CSIC) (Spain)

    2010-05-15

    Magnetometry results have shown that gold NPs ({approx}2 nm in size) protected with phosphine and chlorine ligands exhibit permanent magnetism. When the NPs size decreases down to the subnanometric size range, e.g. undecagold atom clusters, the permanent magnetism disappears. The near edge structure of the X-ray absorption spectroscopy data points out that charge transfer between gold and the capping system occurs in both cases. These results strongly suggest that nearly metallic Au bonds are also required for the induction of a magnetic response. Electron paramagnetic resonance observations indicate that the contribution to magnetism from eventual iron impurities can be disregarded.

  16. Development of a permanent magnet alternative for a solenoidal ion source

    Energy Technology Data Exchange (ETDEWEB)

    Martens, J.; Fahy, A.; Barr, M. [Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308 (Australia); Jardine, A.; Allison, W. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Dastoor, P.C., E-mail: Paul.Dastoor@newcastle.edu.au [Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308 (Australia)

    2014-12-01

    The most sensitive desktop-sized ionizer utilising electron bombardment is currently the solenoidal ion source. We present an alternate design for such an ion source whereby the solenoidal windings of the electromagnet are replaced by a shaped cylindrical permanent magnet in order to reduce the complexity and running costs of the instrument. Through finite element modelling of the magnetic field in COMSOL and experimental measurements on a small-scale prototype magnet stack, we demonstrate the required shape of the permanent magnet in order to generate the needed field, and the necessity of soft iron collars to smooth fluctuations along the central axis.

  17. Controllability and Observability of 2-DOF Permanent Magnet Maglev System with Linear Control

    Institute of Scientific and Technical Information of China (English)

    CUI Tian-shi; OKa koichi; DONG Gui-ju

    2005-01-01

    A new type of 2-DOF(degree of freedom) magnetic levitation system for multi-DOF levitation is proposed. In this system, the force of permanent magnets are used for levitation and controlled by adjusting the reluctance of the magnetic circuit. Using permanent magnets, the feature of this system is effective for saving energy and avoiding heat generation. First, the principle of the levitation system and typical reluctance control methods are described. Second, an experimental device based on the principle is introduced. Finally, the feasibility of this system is considered from linear control theory.

  18. Permanent magnets for Faraday rotators inspired by the design of the magic sphere.

    Science.gov (United States)

    Trénec, Gérard; Volondat, William; Cugat, Orphée; Vigué, Jacques

    2011-08-20

    Faraday polarization rotators are commonly used in laser experiments. Most Faraday materials have a nonnegligible absorption, which is a limiting factor for high power laser optical isolators or for intracavity optical diodes. By using a stronger magnetic field and a shorter length of Faraday material, one can obtain the same polarization rotation and a reduced absorption. In this paper, we describe two permanent magnet arrangements that are easy to build and produce magnetic fields up to 1.7 T, substantially more than commonly used. The field homogeneity is largely sufficient for a 30 dB isolation ratio. We finally discuss the prospects for producing even larger fields with permanent magnets.

  19. Compensation of the magnetization current induced sextupole error at LHC injection field by short lumped permanent sextupole magnets, incorporated into the end configuration of superconducting dipoles

    CERN Document Server

    Asner, A

    1985-01-01

    Compensation of the magnetization current induced sextupole error at LHC injection field by short lumped permanent sextupole magnets, incorporated into the end configuration of superconducting dipoles

  20. Calculation of the Autonomous Mc-Generator with a Permanent Magnet

    Science.gov (United States)

    Gurin, V. E.; Kargin, V. I.; Pikar, A. S.; Popkov, N. F.; Ryaslov, E. A.

    2004-11-01

    Numerical calculations of an autonomous magnetocumulative generator with permanent magnets based on barium oxide are presented. Application of barium oxide magnets allows creation of a closed magnetic circuit with four acting gaps and provides magnetic flux compression with axial geometry. A generator using a permanent magnet does not require an additional energy source thus it is convenient to operate and always ready for activation. Numerical calculation results are discussed here and compared with tests of trial samples. A numerical simulation describes the capture of the magnetic flux, its compression by a copper expanding liner, energy losses to cut the flux and non-liner diffusion of magnetic field in conductors. The optimized autonomous generator design using the MKM-48 permanent magnet is shown. Energy is released from the generator by a low-inductive matching transformer. The generator using permanent magnets and having an explosive charge mass of several tens of grams provides 30 J of magnetic energy, sufficient to drive cascade energy amplifiers of submegajoule range.