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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. Micromagnetism and the microstructure of high-temperature permanent magnets

    International Nuclear Information System (INIS)

    Goll, D.; Kronmueller, H.; Stadelmaier, H.H.

    2004-01-01

    Sm 2 (Co,Cu,Fe,Zr) 17 permanent magnets with their three-phase precipitation structure (cells, cell walls, and lamellae) show two characteristic features which so far are difficult to interpret but which are the prerequisites for high-temperature applications: (1) The hard magnetic properties only develop during the final step of the three-step annealing procedure consisting of homogenization, isothermal aging, and cooling. (2) Depending on the composition and on the annealing parameters, the temperature dependence of the coercivity can be easily changed from the conventional monotonic to the recent nonmonotonic behavior showing coercivities up to 1 T even at 500 K. The magnetic hardening during cooling is due to the fact that the cell walls order chemically and structurally during the cooling process. From an analysis of electron diffraction patterns of the superimposed structures existing before and after cooling it could be proven that a phase transition from a phase mixture of defective phases 2:17, 2:7, and 5:19 to the ordered 1:5 phase takes place in the cell walls during cooling. The nonmonotonic temperature dependence of the coercivity is narrowly related to the magnetic hardening mechanism which can be either pinning or nucleation and results from the magnetic and microstructural properties of the cell walls. These properties have been determined quantitatively from hysteresis loop measurements and from high-resolution transmission electron microscopy and energy dispersive x-ray analysis. Due to the temperature dependence of the intrinsic magnetic properties, the nonmonotonic temperature dependence of the coercivity is found to be determined by repulsive pinning of domain walls at the cell walls at low temperatures, by attractive pinning of domain walls in the cell walls at intermediate temperatures, and by nucleation at high temperatures. This complex temperature behavior is also reflected in characteristic changes of the angular dependence of the

  3. Superconducting permanent magnets for high-temperature operation

    Czech Academy of Sciences Publication Activity Database

    Jirsa, Miloš; Muralidhar, M.

    2004-01-01

    Roč. 54, Suppl. D (2004), D441-D444 ISSN 0011-4626. [Czech and Slovak Conference on Magnetism. Košice, 12.07.2004-15.07.2004] Institutional research plan: CEZ:AV0Z1010914 Keywords : superconducting magnets * ternary LRE-123 compounds * mesoscopic defects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.292, year: 2004

  4. Magnetic superelevation design of Halbach permanent magnet guideway for high-temperature superconducting maglev

    Science.gov (United States)

    Lei, Wuyang; Qian, Nan; Zheng, Jun; Huang, Huan; Zhang, Ya; Deng, Zigang

    2017-07-01

    To improve the curve negotiating ability of high-temperature superconducting (HTS) maglev system, a special structure of magnetic superelevation for double-pole Halbach permanent magnet guideway (PMG) was designed. The most significant feature of this design is the asymmetrical PMG that forms a slanting magnetic field without affecting the smoothness of the PMG surface. When HTS maglev vehicle runs through curves with magnetic superelevation, the vehicle will slant due to asymmetry in magnetic field and the flux-pinning effect of onboard HTS bulks. At the same time, one component of the levitation force provides a part of the centripetal force that reduces lateral acceleration of the vehicle and thus enhances its curve negotiating ability. Furthermore, the slant angle of magnetic superelevation can be adjusted by changing the materials and the thickness of the added permanent magnets. This magnetic superelevation method, together with orographic uplift, can be applied to different requirements of PMG designs. Besides, the applicability of this method would benefit future development of high-speed HTS maglev system.

  5. Magnetic properties of high temperature superconductors and their interaction with high energy permanent magnets

    International Nuclear Information System (INIS)

    Agarwala, A.K.

    1990-01-01

    Magnetic properties of sintered samples of YBCO ceramic superconductors at various temperatures were measured using a vibrating sample magnetometer (VSM). Also, measurements of forces experienced by a well characterized rare earth-transition metal (RE-TM) permanent magnet (PM) interacting with the superconducting YBCO sample cooled in liquid nitrogen, were performed. Based upon the observed hysteretic magnetization properties of these high temperature superconductors (HTS), the HTS-PM interaction force at liquid nitrogen temperature was calculated from first principle, and finally correlated to the force measurement results. With this analysis, magnetic forces between the same HTS and PM system including the levitation as well as suspension effects at liquid-helium temperature are predicted

  6. Application of high-temperature superconducting permanent magnets to synchrotron radiation sources

    Directory of Open Access Journals (Sweden)

    Takashi Tanaka

    2004-09-01

    Full Text Available A simple scheme for field enhancement in synchrotron radiation sources such as undulators and wigglers is proposed, which is based on the fundamental nature of the superconducting loop where the magnetic flux is preserved. A superconductor ring placed to enclose the magnetic pole works as a kind of permanent magnet. The magnetization is performed by electromagnetic induction brought by the opening movement of the magnetic gap. Since neither additional external power supplies nor current leads are necessary, high-temperature bulk superconductors can easily be implemented in this scheme. Calculations to check the effectiveness of the new concept show that the critical current density of the superconductor is crucial to the performance of the synchrotron radiation sources based on this concept. Experiments were performed to verify the principle of the proposed scheme, which gave promising results to strongly support it.

  7. Maglev performance of a double-layer bulk high temperature superconductor above a permanent magnet guideway

    International Nuclear Information System (INIS)

    Deng, Z; Wang, J; Zheng, J; Lin, Q; Zhang, Y; Wang, S

    2009-01-01

    In order to improve the performance of the present high temperature superconducting (HTS) maglev vehicle system, the maglev performance of single- and double-layer bulk high temperature superconductors (HTSC) was investigated above a permanent magnet guideway (PMG). It is found that the maglev performance of a double-layer bulk HTSC is not a simple addition of each layer's levitation and guidance force. Moreover, the applied magnetic field at the position of the upper layer bulk HTSC is not completely shielded by the lower layer bulk HTSC either. 53.5% of the levitation force and 27.5% of the guidance force of the upper layer bulk HTSC are excited in the double-layer bulk HTSC arrangement in the applied field-cooling condition and working gap, bringing a corresponding improvement of 16.9% and 8.8% to the conventional single-layer bulk HTSC. The present research implies that the cost performance of upper layer bulk HTSC is a little low for the whole HTS maglev system.

  8. Maglev performance of a double-layer bulk high temperature superconductor above a permanent magnet guideway

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Z; Wang, J; Zheng, J; Lin, Q; Zhang, Y; Wang, S [Applied Superconductivity Laboratory, Southwest Jiaotong University, Chengdu, 610031 (China)], E-mail: asclab@asclab.cn

    2009-05-15

    In order to improve the performance of the present high temperature superconducting (HTS) maglev vehicle system, the maglev performance of single- and double-layer bulk high temperature superconductors (HTSC) was investigated above a permanent magnet guideway (PMG). It is found that the maglev performance of a double-layer bulk HTSC is not a simple addition of each layer's levitation and guidance force. Moreover, the applied magnetic field at the position of the upper layer bulk HTSC is not completely shielded by the lower layer bulk HTSC either. 53.5% of the levitation force and 27.5% of the guidance force of the upper layer bulk HTSC are excited in the double-layer bulk HTSC arrangement in the applied field-cooling condition and working gap, bringing a corresponding improvement of 16.9% and 8.8% to the conventional single-layer bulk HTSC. The present research implies that the cost performance of upper layer bulk HTSC is a little low for the whole HTS maglev system.

  9. Experimental evaluation of permanent magnet probe flowmeter measuring high temperature liquid sodium flow in the ITSL

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Uiju; Kim, Yun Ho [Nuclear engineering Department, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Kim, Jong-Man; Kim, Tae-Joon [Korea Atomic Energy Research Institute, 1045 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Kim, Sung Joong, E-mail: sungjkim@mit.edu [Nuclear engineering Department, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

    2013-12-15

    Highlights: • An Instrument Test Sodium Loop (ITSL) has been built and tested in various conditions at KAERI. • Free fall of liquid sodium was conducted experimentally and numerically. • A Permanent Magnet Probe Flowmeter (PMPF) was experimented in the ITSL. • Excellent linearity of the PMPF was achieved under high temperature condition. - Abstract: The Instrument Test Sodium Loop (ITSL) installed at Korea Atomic Energy Research Institute (KAERI) is a medium-size experimental facility dedicated to obtaining relevant experimental data of liquid sodium flow characteristics under various thermal hydraulic conditions and sodium purification. The ITSL has been utilized to perform thermal flow measurement of the liquid sodium and to calibrate a Permanent Magnet Probe Flowmeter (PMPF). The primary objective of this study is to obtain liquid sodium flow rate given a wide temperature range using the PMPF. Non-stationary method was adopted for the calibration of the probe given the liquid sodium temperature range of 150–415 °C. A relationship between the measured voltage signal and flow rate was obtained successfully. It is observed that the calibration experiments result in excellent linear relationships between measured voltage and volumetric flow rate at various temperature conditions. Also a computational analysis using FlowMaster, is employed to facilitate the calibration process by predicting the liquid sodium flow rate. Finally the effect of the fluid temperature on thermal flow measurements is discussed in light of the obtained experimental data.

  10. 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.

  11. A two-pole Halbach permanent magnet guideway for high temperature superconducting Maglev vehicle

    International Nuclear Information System (INIS)

    Jing, H.; Wang, J.; Wang, S.; Wang, L.; Liu, L.; Zheng, J.; Deng, Z.; Ma, G.; Zhang, Y.; Li, J.

    2007-01-01

    In order to improve the levitation performance of the high temperature superconducting (HTS) magnetic levitation (Maglev) vehicle, a two-pole Halbach array's permanent magnet guideway (PMG) is proposed, which is called as Halbach PMG. The finite element method (FEM) calculations indicate that Halbach PMG has a wider high-field region than the present PMG of equal PM's transverse section. The levitation force of bulk HTSCs with the present PMG and Halbach PMG are measured. The results show that at different levitation gaps, the force ratios based on the Halbach PMG are about 2.3 times larger than that on the present PMG, which greatly increases the load capability of the system. Therefore, both the numerical analysis and experimental results have confirmed that the Halbach PMG will further enhance the performance of the vehicle and it is possible to decrease the total numbers of onboard HTSCs, reducing overall costs. So based on the Halbach PMG, we further study the width ratios between HTSCs and PMG for making the better use of the onboard HTSCs. Some preliminary results are given. These results are important for further HTS Maglev vehicle system designs using Halbach PMG

  12. 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.

  13. Equivalent Coil Model for Computing Levitation Forces Between Permanent Magnets and High Temperatures Superconductors

    International Nuclear Information System (INIS)

    Cavia Santos, S.; Garcia-Tabares, L.

    1998-05-01

    A new simple theory has been developed for the study of levitation forces between a permanent magnet and a HTc superconductor. This theory is based on the assumption that both, the magnet and the superconductor, can be modelled by an equivalent coil placed on their surface. While the current flowing through the permanent magnet is constant, the equivalent current through the superconductor can be iether corresponding to screen the overall flux or a constant current corresponding to critical current density when the superconductor is saturated. A test facility has been designed and built for measuring levitation forces at variable approaching speeds. Comparison between theoretical and experimental measurements are presented in the report as well as a general description of the test facility. (Author)

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

    Science.gov (United States)

    Wang, B.; Zheng, J.; Che, T.; Zheng, B. T.; Si, S. S.; Deng, Z. G.

    2015-12-01

    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.

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

    International Nuclear Information System (INIS)

    Wang, B.; Zheng, J.; Che, T.; Zheng, B.T.; Si, S.S.; Deng, Z.G.

    2015-01-01

    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. 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.

  17. 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.

  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

  19. Novel High Temperature Magnetic Bearings for Space Vehicle Systems, Phase II

    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...

  20. Novel High Temperature Magnetic Bearings for Space Vehicle Systems, Phase I

    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...

  1. Chemical Synthesis of Next Generation High Energy Product Hybrid SmCo Permanent Magnets for High Temperature Applications

    Science.gov (United States)

    2010-08-01

    and repelling forces (e.g. magnetic separators, latches, torque drives, bearings, etc), energy conversion (e.g. magnetos , generators, alternators... therapies . Additional research includes theoretical and experimental studies of MnC {M = Fe, Ni, Co, etc.) clusters [27], which are cage-like...and millimeter-wave devices (isolators, circulators, phase shifters, filters, etc), energy conversion (e.g. magnetos , generators, alternators, eddy

  2. 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)

  3. 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...

  4. FY 1999 Report on research and development of power storage by high-temperature superconducting flywheel. Research and development of permanent magnet; 1999 nendo koon chodendo flywheel denryoku chozo kenkyu kaihatsu eikyu jishaku no kenkyu kaihatsu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-05-01

    The R and D program is implemented for permanent magnet, as part of the project aimed at commercialization of a 10 MWh-class high-temperature superconducting magnetic bearing type power storage system. A speed of rotation of 28,570 rpm is attained by using an iron intermediate ring for a Pr permanent magnet rotator and reinforcing the rotator with a plastic hoop reinforced with carbon fibers three-fold (CFPR hoop). The speed is increased to 31,300 rpm by interlacing carbon fibers also in the radial direction and replacing iron for the intermediate ring by titanium. The highest speed of rotation of 33,506 rpm is realized by the rotator of permanent magnet of sintered Nd. The magnetic circuit of stronger, more smooth magnetic field needs the permanent magnet of less uneven magnetic flux. The magnet is of a monoaxially anisotropic rare-earth metal, with four-fold magnetic ring bodies having fan-shaped small pieces arranged on each ring. Uneven magnetic flux occurs at the joint between these small pieces. The one-body-ring magnet of radially anisotropic, sintered Nd is developed, and incorporated in the repulsion type magnetic circuit, to reduce unevenness of the magnetic flux. (NEDO)

  5. Superconducting permanent magnets

    International Nuclear Information System (INIS)

    Wipf, S.L.; Laquer, H.L.

    1989-01-01

    The concept of superconducting permanent magnets with fields trapped in shells or cylinders of Type II superconductors is an old one. Unfortunately, the low values of 0.5 to 1T for the first flux jump field, which is independent of the actual current density, have frustrated its implementation with classical Type II superconductors. The fact that the flux jump fields for high temperature superconductors should be an order of magnitude larger at liquid nitrogen temperatures allows us to reconsider these options. Analysis of the hysteresis patterns, based on the critical state model, shows that, if the dimensions are chosen so that the sample is penetrated at a field B/sub p/, which is equal to or just less than the first flux jump field, B/sub fj/, a temporarily applied field of 2B/sub fj/ will trap 0.5 B/sub fj/. Thus for a 90 K superconductor with a B/sub fj/ of 6T, a permanent field of 3 T should be trapped, with an energy product of 1.8 MJ/m/sup 3/ (225 MG . Oe). This is five times as large as for the best permanent magnet materials. The authors discuss means to verify the analysis and the limitations imposed by the low critical current densities in presently available high temperature superconductors

  6. Permanent magnet design for high-speed superconducting bearings

    Science.gov (United States)

    Hull, John R.; Uherka, Kenneth L.; Abdoud, Robert G.

    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.

  7. Permanent magnet design for high-speed superconducting bearings

    International Nuclear Information System (INIS)

    Hull, J.R.; Uherka, K.L.; Abdoud, R.G.

    1996-01-01

    A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure is disclosed. 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. 9 figs

  8. Permanent quadrupole magnets

    International Nuclear Information System (INIS)

    Bush, E.D. Jr.

    1976-01-01

    A family of quadrupole magnets using a soft iron return yoke and circular cross-section permanent magnet poles were fabricated to investigate the feasibility for use in ion or electron beam focusing applications in accelerators and transport lines. Magnetic field measurements yielded promising results. In fixed-field applications, permanent magnets with sufficient gradients would be a low cost substitute for conventional electromagnets, eliminating the need for power supplies, associated wiring, and cooling. (author)

  9. Introduction to permanent magnets

    International Nuclear Information System (INIS)

    Zijlstra, H.

    1985-01-01

    Some general considerations concerning the application of permanent magnets are developed. The relevant magnet properties are discussed, with particular reference to Nd-Fe-B alloy. The author comes to the following conclusions; the air gap field B should be high, for high electrical efficiency; the magnet should face the air gap, for efficient use of the magnet material; the magnet material should therefore have a high remanence; and the new Nd-Fe-B magnet fits in nicely, having (potentially) the highest remanence ever reported in permanent magnets, combined with sufficient coercivity to sustain it

  10. Permanent quadrupole magnets

    International Nuclear Information System (INIS)

    Bush, E.D. Jr.

    1976-01-01

    A family of quadrupole magnets using a soft iron return yoke and circular cross-section permanent magnet poles were fabricated to investigate the feasibility for use in ion or electron beam focusing applications in accelerators and transport lines. Magnetic field measurements yielded promising results. In fixed-field applications, permanent magnets with sufficient gradients would be a low cost substitute for conventional electromagnets, eliminating the need for power supplies, associated wiring, and cooling. Based on preliminary tests, it was seen that permanent quadrupole magnets can offer a low cost, reliable solution in applications requiring small, fixed-field focusing devices for use in ion or electron-beam transport systems. Permanent magnets do require special considerations in design, fabrication, handling, and service that are different than encountered in conventional quadrupole magnets. If these basic conditions are satisfied, the resulting beam-focusing device would be stable, maintenance free, with virtually an indefinite lifetime

  11. Operation and design selection of high temperature superconducting magnetic bearings

    International Nuclear Information System (INIS)

    Werfel, F N; Floegel-Delor, U; Riedel, T; Rothfeld, R; Wippich, D; Goebel, B

    2004-01-01

    Axial and radial high temperature superconducting (HTS) magnetic bearings are evaluated by their parameters. Journal bearings possess advantages over thrust bearings. High magnetic gradients in a multi-pole permanent magnet (PM) configuration, the surrounding melt textured YBCO stator and adequate designs are the key features for increasing the overall bearing stiffness. The gap distance between rotor and stator determines the specific forces and has a strong impact on the PM rotor design. We report on the designing, building and measuring of a 200 mm prototype 100 kg HTS bearing with an encapsulated and thermally insulated melt textured YBCO ring stator. The encapsulation requires a magnetically large-gap (4-5 mm) operation but reduces the cryogenic effort substantially. The bearing requires 3 l of LN 2 for cooling down, and about 0.2 l LN 2 h -1 under operation. This is a dramatic improvement of the efficiency and in the practical usage of HTS magnetic bearings

  12. New permanent magnets

    Science.gov (United States)

    Müller, K.-H.; Krabbes, G.; Fink, J.; Gruß, S.; Kirchner, A.; Fuchs, G.; Schultz, L.

    2001-05-01

    Permanent magnets play an important role and are widely spread in daily-life applications. Due to their very low costs, large availability of the row materials and their high chemical stability, hard ferrites are still dominant in the permanent magnet market although their relatively poor magnetic properties are a distinct disadvantage. Today's high-performance magnets are mostly made from Nd 2Fe 14B. The aim of research is to combine the large spontaneous magnetization of 3d metals with strong anisotropy fields known from rare-earth transition-metal compounds and, at the same time, to maintain a high value of the Curie temperature. However, the number of iron-rich rare-earth intermetallics is very limited and, consequently, not much success can be noted in this field for the last 10 years. One alternative concept is to use magnetic fields trapped in type II superconductors where much higher fields can be achieved compared to conventional rare-earth magnets. Very recently, we obtained a trapped field as high as 14.4 T in a melt-textured YBCO bulk sample of a few centimeters in diameter. This is the highest value ever achieved in a bulk superconductor. The trapped field of a superconductor is not governed by the Laplace equation and, therefore, levitation works without any additional (active) stabilization. The disadvantage of these magnets is their low working temperature (of liquid nitrogen and below).

  13. Variable Permanent Magnet Quadrupole

    International Nuclear Information System (INIS)

    Mihara, T.; Iwashita, Y.; Kyoto U.; Kumada, M.; NIRS, Chiba; Spencer, C.M.; SLAC

    2007-01-01

    A permanent magnet quadrupole (PMQ) is one of the candidates for the final focus lens in a linear collider. An over 120 T/m strong variable permanent magnet quadrupole is achieved by the introduction of saturated iron and a 'double ring structure'. A fabricated PMQ achieved 24 T integrated gradient with 20 mm bore diameter, 100 mm magnet diameter and 20 cm pole length. The strength of the PMQ is adjustable in 1.4 T steps, due to its 'double ring structure': the PMQ is split into two nested rings; the outer ring is sliced along the beam line into four parts and is rotated to change the strength. This paper describes the variable PMQ from fabrication to recent adjustments

  14. Magnetic memory effects in high temperature superconductors

    International Nuclear Information System (INIS)

    Rockenbauer, A.

    1989-01-01

    Microwave absorption of high temperature oxide superconductors MBa 2 Cu 3 O 7 (M = Y, Er, Dy, Ho, Lu, Tm, Gd) at 77 K have been studied by ESR. In granular samples diamagnetic zero-field resonance and strong ESR baseline hysteresis have been observed: for increasing field sweep - a high, for decreasing one - a low, while in constant field the baseline approaches the middle position with kinetics typical of spin-glasses. The hysteresis amplitude, i.e. the deviation of high and low baselines, possesses maximum at zero field if the sample is cooled down in zero field. In case of field cooling both the diamagnetic resonance and hysteresis maximum are shifted as a function of relative direction of the fields where the samples are cooled and measured, respectively. The shift is caused by the remanent diamagnetism of trapped fluxons. The hysteresis critically depends on the modulation amplitude of magnetic field, and no hysteresis can be observed if the microwave absorption is detected without field modulation. By applying saw-tooth sweep the spin-glass can be driven between two extreme hysteresis states, and the ESR response is rectangular for large saw-tooth amplitude and linear - for small one, while for intermediate amplitudes the recording shows characteristic memory effects. The hysteresis memory is explained in terms of loop distribution of fluxons. In the single crystal the fluxon absorptions are also detected and the separation of fluxon lines can be related to the hysteresis in granular samples. (author)

  15. Cryogenic Permanent Magnet Undulators

    International Nuclear Information System (INIS)

    Chavanne, J.; Lebec, G.; Penel, C.; Revol, F.; Kitegi, C.

    2010-01-01

    For an in-vacuum undulator operated at small gaps the permanent magnet material needs to be highly resistant to possible electron beam exposure. At room temperature, one generally uses Sm 2 Co 17 or high coercivity NdFeB magnets at the expense of a limited field performance. In a cryogenic permanent magnet undulator (CPMU), at a temperature of around 150 K, any NdFeB grade reveals a coercivity large enough to be radiation resistant. In particular, very high remanence NdFeB material can be used to build undulators with enhanced field and X-ray brilliance at high photon energy provided that the pre-baking of the undulator above 100 deg. C can be eliminated. The ESRF has developed a full scale 2 m long CPMU with a period of 18 mm. This prototype has been in operation on the ID6 test beamline since January 2008. A significant effort was put into the characterization of NdFeB material at low temperature, the development of dedicated magnetic measurement systems and cooling methods. The measured heat budget with beam is found to be larger than expected without compromising the smooth operation of the device. Leading on from this first experience, new CPMUs are currently being considered for the upgrade of the ESRF.

  16. Equivalent Coil Model for Computing Levitation Forces Between Permanent Magnets and High Temperatures Superconductors; Modelo de Espira Equivalente para el Calculo de Fuerzas de Levitacion Magnetica entre Imanes Permanentes y Superconductores de Alta Temperatura Critica

    Energy Technology Data Exchange (ETDEWEB)

    Cavia Santos, S; Garcia-Tabares, L

    1998-05-01

    A new simple theory has been developed for the study of levitation forces between a permanent magnet and a HTc superconductor. This theory is based on the assumption that both, the magnet and the superconductor, can be modelled by an equivalent coil placed on their surface. While the current flowing through the permanent magnet is constant, the equivalent current through the superconductor can be iether corresponding to screen the overall flux or a constant current corresponding to critical current density when the superconductor is saturated. A test facility has been designed and built for measuring levitation forces at variable approaching speeds. Comparison between theoretical and experimental measurements are presented in the report as well as a general description of the test facility. (Author)

  17. 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 regenerator and desiredinternal magnetic field. It is shown that to produce a 1 T internal field in theregenerator a permanent magnet of hundreds of kilograms is needed or an area ofsuperconducting tape of tens of square meters. The cost of cooling the SC solenoidis shown to be a small fraction of the cost...... of the SC tape. Assuming a cost ofthe SC tape of 6000 $/m2 and a price of the permanent magnet of 100 $/kg, thesuperconducting solenoid is shown to be a factor of 0.3-3 times more expensive thanthe permanent magnet, for a desired field from 0.5-1.75 T and the geometrical aspectratio of the regenerator...

  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. Magnetic spring based on two permanent magnets

    International Nuclear Information System (INIS)

    Tsivilitsin, V.Yu.; Mil'man, Yu.V.; Goncharuk, V.A.; Bondar, I.B.

    2011-01-01

    A new type of the magnetic spring construction 'two permanent magnets' has been considered. A mathematical expression for the estimation of a pulling-in force has been offered. This expression is verified experimentally on the produced operating magnetic spring. The theoretical and experimental data are in good accordance. A number of advantages of the magnetic spring over the construction 'permanent magnet - magnetic circuit' such as an insignificant friction force between two magnets and a higher pulling force are discussed.

  1. High performance permanent magnet materials

    International Nuclear Information System (INIS)

    Sankar, S.G.; Herbst, J.F.; Koon, N.C.

    1987-01-01

    This book contains 25 selections. Some of the titles are: Initial magnetization behavior of rapidly quenched neodymium-iron-boron magnets; Optimization of liquid dynamic compaction for Fe-Nd-B magnet alloys; Misch-metal and/or aluminum substitutions in Nd-Fe-B permanent magnets; and NdFeB magnets with improved temperature characteristics

  2. Inorganic Nanostructured High-Temperature Magnet Wires, Phase I

    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...

  3. Topology optimized permanent magnet systems

    Science.gov (United States)

    Bjørk, R.; Bahl, C. R. H.; Insinga, A. R.

    2017-09-01

    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. The Halbach cylinder is topology optimized with iron and an increase of 15% in magnetic efficiency is shown. A topology optimized structure to concentrate a homogeneous field is shown to increase the magnitude of the field by 111%. Finally, a permanent magnet with alternating high and low field regions is topology optimized and a Λcool figure of merit of 0.472 is reached, which is an increase of 100% compared to a previous optimized design.

  4. Topology optimized permanent magnet systems

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Bahl, Christian; Insinga, Andrea Roberto

    2017-01-01

    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. The Halbach cylinder is topology optimized with iron...... and an increase of 15% in magnetic efficiency is shown. A topology optimized structure to concentrate a homogeneous field is shown to increase the magnitude of the field by 111%. Finally, a permanent magnet with alternating high and low field regions is topology optimized and a ΛcoolΛcool figure of merit of 0...

  5. Cryocooler applications for high-temperature superconductor magnetic bearings

    International Nuclear Information System (INIS)

    Niemann, R. C.

    1998-01-01

    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

  6. Periodic permanent magnet focused klystron

    Science.gov (United States)

    Ferguson, Patrick; Read, Michael; Ives, R Lawrence

    2015-04-21

    A periodic permanent magnet (PPM) klystron has beam transport structures and RF cavity structures, each of which has permanent magnets placed substantially equidistant from a beam tunnel formed about the central axis, and which are also outside the extent of a cooling chamber. The RF cavity sections also have permanent magnets which are placed substantially equidistant from the beam tunnel, but which include an RF cavity coupling to the beam tunnel for enhancement of RF carried by an electron beam in the beam tunnel.

  7. Conduction cooled high temperature superconducting dipole magnet for accelerator applications

    DEFF Research Database (Denmark)

    Zangenberg, N.; Nielsen, G.; Hauge, N.

    2012-01-01

    A 3T proof-of-principle dipole magnet for accelerator applications, based on 2nd generation high temperature superconducting tape was designed, built, and tested by a consortium under the lead of Danfysik. The magnet was designed to have a straight, circular bore with a good field region of radius...

  8. Rare earth permanent magnet with easy magnetization

    International Nuclear Information System (INIS)

    Kim, A.S.; Camp, F.E.

    1998-01-01

    Rare earth permanent magnets have high energy products and coercivities, and thus the volume miniaturization of magnetic devices has been possible with improved magnetic performance. Although the high energy products of these rare earth permanent magnets provide substantial advantages for magnetic design and application, the strong magnetic force of the magnetized magnets makes assembly difficult. Therefore, a special device is needed to assemble the magnetized magnets. On the other hand, unmagnetized magnets are assembled and then they are magnetized. The assembled magnets are generally more difficult to magnetize than unassembled magnets because a much less effective magnetic field may be applied to them. This is particularly true for the rare earth permanent magnets because they usually need a much higher magnetic field to be fully magnetized than alnico or ferrite magnets. To obtain optimum magnetic properties, the required minimum magnetizing fields for SmCo 5 , Sm 2 TM 17 and Nd 2 Fe 14 B magnets were reported as 25-30 kOe, 45-60 kOe and 25-30 kOe, respectively. If the required magnetizing field for full saturation could be lowered, the effective utilization of magnetic properties would be maximized and the magnetic design option could be expanded with reduced restrictions. To meet this demand, we have sought to lower the field required for full magnetic saturation, and found that an increase in Dy content in R-(Fe,Co,Cu)-B type magnets lowers the field required for full saturation as well as improves the temperature stability. By increasing the H ci with Dy addition from 14 kOe to 24 and 34 kOe, the field required for full magnetic saturation decreases from about 20 to 15 and 10 kOe, respectively. This dual benefit will open up new application areas with more freedom for magnet design options. The mechanism for the lower magnetizing fields will be discussed. (orig.)

  9. 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...... of the magnetostatic interaction energy. For comparison, the forces involved are also calculated numerically using finite elements methods. Based on the conservation of the magnetostatic and kinetic energies, the exit and asymptotic velocities are determined. The derived formulas can be used to optimize the generated...... forces and motion of the inner cylindrical magnet....

  10. Rare earth permanent magnets

    International Nuclear Information System (INIS)

    Higuchi, Akira

    1992-01-01

    This paper is a review of the new technologies for Nd-Fe-B magnets, their markets and future perspectives. This type of magnet is a product approaching the ideal magnet, and is based upon the development history of two previous generations of Sm-Co alloy systems and the recent progress on physical and metallurgical research. (orig.)

  11. 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......, with respect to a linear objective functional. We illustrate the approach with results for magnet design problems from different areas, such as a permanent magnet electric motor, a beam focusing quadrupole magnet for particle accelerators and a rotary device for magnetic refrigeration....

  12. Self-propagating high temperature synthesis and magnetic

    Indian Academy of Sciences (India)

    Ni–Zn ferrite powders were synthesized by self-propagating high temperature synthesis (SHS) method. X-ray diffraction, TEM and vibrating sample magnetometry (VSM) were used to characterize the phase composition, microstructure and magnetic properties of the combustion products. The effect of the combustion ...

  13. 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.

  14. 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....

  15. 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.

  16. Laced permanent magnet quadrupole drift tube magnets

    International Nuclear Information System (INIS)

    Feinberg, B.; Behrsing, G.U.; Halbach, K.; Marks, J.S.; Morrison, M.E.; Nelson, D.H.

    1988-10-01

    A laced permanent magnet quadrupole drift tube magnet has been constructed for a proof-of-principle test. The magnet is a conventional tape-wound quadrupole electromagnet, using iron pole- pieces, with the addition of permanent magnet material (neodymium iron) between the poles to reduce the effects of saturation. The iron is preloaded with magnetic flux generated by the permanent magnet material, resulting in an asymmetrical saturation curve. Since the polarity of the quadrupole magnets in a drift tube linac is not reversed we can take advantage of this asymmetrical saturation to provide greater focusing strength. The magnet configuration has been optimized and the vanadium permendur poles needed in a conventional quadrupole have been replaced with iron poles. The use of permanent magnet material has allowed us to increase the focusing strength of the magnet by about 20% over that of a conventional tape-wound quadrupole. Comparisons will be made between this magnet and the conventional tape-wound quadrupole. 3 refs., 5 figs

  17. High temperature superconductors for fusion magnets -influence of neutron irradiation

    International Nuclear Information System (INIS)

    Chudy, M.; Eisterer, M.; Weber, H. W.

    2010-01-01

    In this work authors present the results of study of influence of neutron irradiation of high temperature superconductors for fusion magnets. High temperature superconductors (type of YBCO (Yttrium-Barium-Copper-Oxygen)) are strong candidates to be applied in the next step of fusion devices. Defects induced by fast neutrons are effective pinning centres, which can significantly improve critical current densities and reduce J c anisotropy. Due to induced lattice disorder, T c is reduced. Requirements for ITER (DEMO) are partially achieved at 64 K.

  18. Balancing permanent magnet arrays

    NARCIS (Netherlands)

    Krechting, P.T.; Lomonova, E.; Jansen, J.W.

    2009-01-01

    High resolution electron beam imaging (E-beam) has found wide usage in industry in photolithography and semiconductor inspection systems. E-beam inspection, which takes place in vacuum, is very sensitive to magnetic fields, and requires highly dynamic and accurate actuators Piezo "walking" motors

  19. Magnetic guns with cylindrical permanent magnets

    Czech Academy of Sciences Publication Activity Database

    Vokoun, David; Beleggia, M.; Heller, Luděk

    2012-01-01

    Roč. 324, č. 9 (2012), s. 1715-1719 ISSN 0304-8853 R&D Projects: GA ČR(CZ) GAP107/11/0391; GA AV ČR IAA100100920 Institutional research plan: CEZ:AV0Z10100520 Keywords : permanent magnet * cylindrical magnet * Earnshaw's theorem * magnetic gun * magnetostatic interaction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.826, year: 2012 http://www.sciencedirect.com/science/article/pii/S0304885311008997

  20. Plasma sprayed samarium--cobalt permanent magnets

    International Nuclear Information System (INIS)

    Willson, M.C.; Janowiecki, R.J.

    1975-01-01

    Samarium--cobalt permanent magnets were fabricated by arc plasma spraying. This process involves the injection of relatively coarse powder particles into a high-temperature gas for melting and spraying onto a substrate. The technique is being investigated as an economical method for fabricating cobalt--rare earth magnets for advanced traveling wave tubes and cross-field amplifiers. Plasma spraying permits deposition of material at high rates over large areas with optional direct bonding to the substrate, and offers the ability to fabricate magnets in a variety of shapes and sizes. Isotropic magnets were produced with high coercivity and good reproducibility in magnetic properties. Post-spray thermal treatments were used to enhance the magnetic properties of sprayed deposits. Samarium--cobalt magnets, sprayed from samarium-rich powder and subjected to post-spray heat treatment, displayed energy products in excess of 9 million gauss-oersteds and coercive forces of approximately 6000 oersteds. Bar magnet arrays were constructed by depositing magnets on ceramic substrates. (auth)

  1. Plasma sprayed samarium--cobalt permanent magnets

    International Nuclear Information System (INIS)

    Willson, M.C.; Janowiecki, R.J.

    1975-01-01

    Samarium--Co permanent magnets were fabricated by arc plasma spraying. This process involves the injection of relatively coarse powder particles into a high temperature gas for melting and spraying onto a substrate. The technique is being investigated as an economical method for fabricating Co--rare earth magnets for advanced traveling wave tubes and cross-field amplifiers. Plasma spraying permits deposition of material at high rates over large areas with optional direct bonding to the substrate, and offers the ability to fabricate magnets in a variety of shapes and sizes. Isotropic magnets were produced with high coercivity and good reproducibility in magnetic properties. Post-spray thermal treatments were used to enhance the magnetic properties of sprayed deposits. Samarium--Co magnets, sprayed from Sm-rich powder and subjected to post-spray heat treatment, displayed energy products in excess of 9 million G-Oe and coercive forces of approximately 6000 Oe. Bar magnet arrays were constructed by depositing magnets on ceramic substrates

  2. 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 metallic...

  3. Design prospect of remountable high-temperature superconducting magnet

    Energy Technology Data Exchange (ETDEWEB)

    Hashizume, Hidetoshi, E-mail: hidetoshi.hashizume@qse.tohoku.ac.jp; Ito, Satoshi

    2014-10-15

    The remountable (mountable and demountable repeatedly) high-temperature superconducting (HTS) magnet has been proposed for huge and complex superconducting magnets in future fusion reactors to fabricate and repair easily the magnet and access inner structural components. This paper summarizes progress in R and D activities of mechanical joints of HTS conductors in terms of the electrical resistance and heat transfer performance at the joint region. The latest experimental results show the low joint resistance, 4 nΩ under 70 kA current condition using REBCO HTS conductor with mechanical lap joint system, and for the cooling system the maximum heat flux of 0.4 MW/m{sup 2} is removed by using bronze sintered porous media with sub-cooled liquid nitrogen. These values indicate that there is large possibility to design the remountable HTS magnet for fusion reactors.

  4. Permanent magnets including undulators and wigglers

    CERN Document Server

    Bahrdt, J

    2010-01-01

    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 concentrates on the applications of permanent magnets in accelerators starting from dipoles and quadrupoles on to wigglers and undulators.

  5. Quasispin model of itinerant magnetism: High-temperature theory

    International Nuclear Information System (INIS)

    Liu, S.H.

    1977-01-01

    The high-temperature properties of itinerant magnetic systems are examined by using the coherent-potential approximation. We assume a local moment on each atom so that at elevated temperatures there is a number of reversed spins. The coherent potential is solved, and from that the moment on each atom is determined self-consistently. It is found that when the condition for ferromagnetic ordering is satisfied, the local moments persist even above the critical temperature. Conversely, if local moments do not exist at high temperatures, the system can at most condense into a spin-density-wave state. Furthermore, spin-flip scatterings of the conduction electrons from the local moments give rise to additional correlation not treated in the coherent-potential approximation. This correlation energy is an important part of the coupling energy of the local moments. The relations between our work and the theories of Friedel, Hubbard, and others are discussed

  6. 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.

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

    Science.gov (United States)

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

    2009-02-01

    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.

  8. High temperature structural and magnetic properties of cobalt nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Ait Atmane, Kahina [Univ. Paris Diderot, Sorbonne Paris Cite, ITODYS, UMR CNRS 7086, 15 rue J.-A. de Baief, 75205 Paris Cedex 13 (France); Zighem, Fatih [Laboratoire Leon Brillouin, CEA CNRS UMR 12, IRAMIS, CEA-Saclay, 91191 Gif sur Yvette (France); Soumare, Yaghoub [Univ. Paris Diderot, Sorbonne Paris Cite, ITODYS, UMR CNRS 7086, 15 rue J.-A. de Baief, 75205 Paris Cedex 13 (France); Ibrahim, Mona; Boubekri, Rym [Universite de Toulouse, LPCNO, INSA CNRS UMR 5215, 135 av. de Rangueil, 31077 Toulouse Cedex 4 (France); Maurer, Thomas [Laboratoire Leon Brillouin, CEA CNRS UMR 12, IRAMIS, CEA-Saclay, 91191 Gif sur Yvette (France); Margueritat, Jeremie [Univ. Paris Diderot, Sorbonne Paris Cite, ITODYS, UMR CNRS 7086, 15 rue J.-A. de Baief, 75205 Paris Cedex 13 (France); Piquemal, Jean-Yves, E-mail: jean-yves.piquemal@univ-paris-diderot.fr [Univ. Paris Diderot, Sorbonne Paris Cite, ITODYS, UMR CNRS 7086, 15 rue J.-A. de Baief, 75205 Paris Cedex 13 (France); Ott, Frederic; Chaboussant, Gregory [Laboratoire Leon Brillouin, CEA CNRS UMR 12, IRAMIS, CEA-Saclay, 91191 Gif sur Yvette (France); Schoenstein, Frederic; Jouini, Noureddine [LSPM, CNRS UPR 9001, Universite Paris XIII, Institut Galilee, 99 av. J.-B. Clement, 93430 Villetaneuse (France); Viau, Guillaume, E-mail: gviau@insa-toulouse.fr [Universite de Toulouse, LPCNO, INSA CNRS UMR 5215, 135 av. de Rangueil, 31077 Toulouse Cedex 4 (France)

    2013-01-15

    We present in this paper the structural and magnetic properties of high aspect ratio Co nanoparticles ({approx}10) at high temperatures (up to 623 K) using in-situ X ray diffraction (XRD) and SQUID characterizations. We show that the anisotropic shapes, the structural and texture properties are preserved up to 500 K. The coercivity can be modelled by {mu}{sub 0}H{sub C}=2(K{sub MC}+K{sub shape})/M{sub S} with K{sub MC} the magnetocrystalline anisotropy constant, K{sub shape} the shape anisotropy constant and M{sub S} the saturation magnetization. H{sub C} decreases linearly when the temperature is increased due to the loss of the Co magnetocrystalline anisotropy contribution. At 500 K, 50% of the room temperature coercivity is preserved corresponding to the shape anisotropy contribution only. We show that the coercivity drop is reversible in the range 300-500 K in good agreement with the absence of particle alteration. Above 525 K, the magnetic properties are irreversibly altered either by sintering or by oxidation. - Graphical abstract: We present in this paper the structural and magnetic properties of high aspect ratio Co nanorods ({approx}10) at high temperatures (up to 623 K) using in-situ X-ray diffraction and SQUID characterizations. We show that the anisotropic shapes, the structural and texture properties are preserved up to 500 K. Above 525 K, the magnetic properties are irreversibly altered either by sintering or by oxidation. Highlights: Black-Right-Pointing-Pointer Ferromagnetic Co nanorods are prepared using the polyol process. Black-Right-Pointing-Pointer The structural and texture properties of the Co nanorods are preserved up to 500 K. Black-Right-Pointing-Pointer The magnetic properties of the Co nanorods are irreversibly altered above 525 K.

  9. Development of high temperature superconductors for magnetic field applications

    International Nuclear Information System (INIS)

    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 perturbations 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 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

  10. Permanent magnet-based MRI

    Science.gov (United States)

    Cole, David Mitchell

    1997-10-01

    The principal goal of this project is to design and build a low-cost, imaging quality permanent magnet, together with the requisite shim, gradient, and radiofrequency coils, and to integrate the magnet with an existing imaging station. There are commercial products presently available that are very similar to this imager, but information about these products is proprietary. We present here all of the details concerning the design and the manufacturing process for constructing the permanent magnet, and include suggestions for improvement. Specifically, the prototype has a mass of about 150 kilograms and is therefore portable. It's C-type geometry allows maximum access to the imaging region, which is an oblate sphere about 0.5 inches in diameter centered in a 4.7 inch air gap between two seven-inch diameter polefaces. It is hoped that this imaging magnet will serve as the prototype for a series of larger versions that will be clinically useful and affordable to physicians in developing nations. To this end, scientists in the United States and Mexico have begun to collaborate with the intention to create an MRI institute in Mexico that will train new students in this discipline, and fabricate improved imagers. The prototype resulting from this work will seed the creation of this institute, and is intended to entice students into the study of MRI by enabling hands-on interaction with an otherwise prohibitively expensive instrument.

  11. Generation of magnetic fields for accelerators with permanent magnets

    International Nuclear Information System (INIS)

    Meinander, T.

    1994-01-01

    Commercially available permanent magnet materials and their properties are reviewed. Advantages and disadvantages of using permanent magnets as compared to electromagnets for the generation of specific magnetic fields are discussed. Basic permanent magnet configurations in multipole magnets and insertion devices are presented. (orig.)

  12. Small magnetic energy storage systems using high temperature superconductors

    International Nuclear Information System (INIS)

    Kumar, B.

    1991-01-01

    This paper reports on magnetic energy storage for power systems that has been considered for commercial utility power, air and ground mobile power sources, and spacecraft applications. Even at the current technology limits of energy storage (100 KJ/Kg*), superconducting magnetic energy storage inductors do not offer a strong advantage over state-of-the-art batteries. The commercial utility application does not have a weight and volume limitation, and is under intense study in several countries for diurnal cycle energy storage and high power delivery. The advent of high temperature superconductors has reduced one of the penalties of superconducting magnetic energy storage in that refrigeration and cryocontainers become greatly simplified. Still, structural and current density issues that limit the energy density and size of superconducting inductors do not change. Cold weather starting of aircraft engines is an application where these limitations are not as significant, and where current systems lack performance. The very cold environments make it difficult to achieve high power densities in state-of-the-art batteries and hydraulically activated starters. The same cold environments make it possible to cool superconducting systems for weeks using a single charge of liquid nitrogen. At the same, the ground carts can handle the size and weight of superconducting magnetic storage (SMES) devices

  13. Use of high temperature superconductors for future fusion magnet systems

    Energy Technology Data Exchange (ETDEWEB)

    Fietz, W H [Forschungszentrum Karlsruhe, Institut fuer Technische Physik, Karlsruhe (Germany); Celentano, G; Della Corte, A [Superconductivity Division, ENEA - Frascati Research Center, Frascati (Italy); Goldacker, W; Heller, R; Komarek, P; Kotzyba, G; Nast, R; Obst, B; Schlachter, S I; Schmidt, C; Zahn, G [Forschungszentrum Karlsruhe, Institut fuer Technische Physik, Karlsruhe (Germany); Pasztor, G; Wesche, R [Centre de Recherches en Physique des Plasmas, Villingen (Switzerland); Salpietro, E; Vostner, A [European Fusion Development Agreement, Close Support Unit, Garching (Germany)

    2005-01-01

    With the construction of ITER the feasibility of a fusion machine will be demonstrated. To commercialize fusion it is essential to keep losses as small as possible in future fusion power plants. One major component where losses can be strongly reduced is the cooling system. For example in ITER where efficiency is not a major goal, a cooling power of 64 kW at 4.4 K is foreseen taking more than 20 MW electric power. Considering the size of future commercial fusion machines this consumption of electric power for cooling will even be higher. With a magnet system working at 20 K a fusion machine would work more efficient by a factor of 5-10 with respect to electric power consumption for cryogenics. Even better than that, would be a machine with a magnet system operating at 65 K to 77 K. In this case liquid nitrogen could be used as coolant saving money for investment and operation costs. Such an increase in the operating temperature of the magnet system can be achieved by the use of High- Temperature Superconductors (HTS). In addition the use of HTS would allow much smaller efforts for thermal shielding and alternative thermal insulation concepts may be possible, e.g. for an HTS bus bar system. This contribution will give an overview about status, promises and challenges of HTS conductors on the way to an HTS fusion magnet system beyond ITER. (author)

  14. Modern permanent magnetic materials - preparation and properties

    International Nuclear Information System (INIS)

    Rodewald, W.

    1989-01-01

    First of all, the basic properties of the classical (steel, AlNiCo) permanent magnetic materials and the modern rare-earth (RE) permanent magnetic materials are compared. Since the properties of RE permanent magnets depend on the particular production process, the fundamentals of the main industrial processes (powder metallurgy, rapid-solidification technique) are described and the typical properties are explained. Furthermore the production processes in development such as mechanical alloying, melt spinning technique and extrusion upsetting are briefly outlined. For applying the permanent magnets, they have to be completely magnetized. The magnetization behaviour of the various RE permanent magnets is discussed by means of the internal demagnetization curve. Finally the various influences on the temperature stability of RE permanent magnets are compiled. (orig./MM) [de

  15. Permanent magnet based dipole magnets for next generation light sources

    Directory of Open Access Journals (Sweden)

    Takahiro Watanabe

    2017-07-01

    Full Text Available We have developed permanent magnet based dipole magnets for the next generation light sources. Permanent magnets are advantageous over electromagnets in that they consume less power, are physically more compact, and there is a less risk of power supply failure. However, experience with electromagnets and permanent magnets in the field of accelerators shows that there are still challenges to replacing main magnets of accelerators for light sources with permanent magnets. These include the adjustability of the magnetic field, the temperature dependence of permanent magnets, and the issue of demagnetization. In this paper, we present a design for magnets for future light sources, supported by experimental and numerical results.

  16. Permanent Magnet Dipole for DIRAC Design Report

    CERN Document Server

    Vorozhtsov, Alexey

    2012-01-01

    Two dipole magnets including one spare unit are needed for the for the DIRAC experiment. The proposed design is a permanent magnet dipole. The design based on Sm2Co17 blocks assembled together with soft ferromagnetic pole tips. The magnet provides integrated field strength of 24.6 10-3 T×m inside the aperture of 60 mm. This Design Report summarizes the main magnetic and mechanic design parameters of the permanent dipole magnets.

  17. 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.

  18. Research and development project for flywheel energy storage system using high-temperature superconducting magnetic bearing

    International Nuclear Information System (INIS)

    Shinagawa, Jiro; Ishikawa, Fumihiko

    1996-01-01

    Recent progress in the research and development of an yttrium-based oxide high-temperature superconductor has enabled the production of a large-diameter bulk with a strong flux-pinning force. A combination of this superconductor and a permanent magnet makes it feasible to fabricate a non-contact, non-controlled superconducting magnetic bearing with a very small rotational loss. Use of the superconducting magnetic bearing for a flywheel energy storage system may pave the way to the development of a new energy storage system that has great energy storage efficiency. >From relevant data measured with a miniature model of the high-temperature superconducting magnetic bearing, a conceptual design of an 8 MWh flywheel energy storage system was developed, using the new bearing which proved to be potentially capable of achieving a high energy storage efficiency of 84%. A 100 Wh-class experimental system was install that attained a high revolution rate of 17.000 rpm. (author)

  19. 3-D analysis of eddy current in permanent magnet of interior permanent magnet motors

    International Nuclear Information System (INIS)

    Kawase, Yoshihiro; Yamaguchi, Tadashi; Fukanaga, Hiromu; Ito, Shokichi

    2002-01-01

    Interior permanent magnet motors are widely used in various fields. However, in high-speed operations, it is important to decrease the eddy current loss in the permanent magnet. In order to decrease the eddy current loss, we propose to divide the permanent magnet. In this paper, we clarified the effect of division of permanent magnet on the eddy current loss using the 3-D finite element method. (Author)

  20. Numerical solutions to the critical state in a magnet-high temperature superconductor interaction

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Alonso, D; Coombs, T A; Campbell, A M [Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ (United Kingdom)

    2005-02-01

    This paper presents an algorithm to simulate the electromagnetic behaviour of devices containing high temperature superconductors in axially symmetric problems. The numerical method is built within the finite element method. The electromagnetic properties of HTSCs are described through the critical-state model. Measurements of the axial force between a permanent magnet and a melt-textured YBCO puck are obtained in order to validate the method. This simple system is modelled so that the proposed method obtains the current distribution and electromagnetic fields in the HTSC. The forces in the interaction between the magnet and the HTSC puck can then be calculated. A comparison between experimental and simulation results shows good matching. The simplification of using the critical-state model and ignoring flux creep in this type of configuration is also explored.

  1. Macroscopic simulation of isotropic permanent magnets

    International Nuclear Information System (INIS)

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

    2016-01-01

    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. - Highlights: • Simulations of isotropic permanent magnets. • Accurate calculation of remanence magnetization and strayfield. • Comparison with strayfield measurements and anisotropic magnet simulations. • Efficient 3D FEM–BEM coupling for solution of Maxwell equations.

  2. Nanocrystalline permanent magnets with enhanced properties

    International Nuclear Information System (INIS)

    Leonowicz, M.

    2002-01-01

    Parameters of permanent magnets result from the combination of intrinsic properties such as saturation magnetization, magnetic exchange, and magnetocrystalline energy, as well as microstructural parameters such as phase structure, grain size, and orientation. Reduction of grain size into nanocrystalline regime (∼ 50 nm) leads to the enhanced remanence which derives from ferromagnetic exchange coupling between highly refined grains. In this study the fundamental phenomena, quantities, and structure parameters, which define nanophase permanent magnets are presented and discussed. The theoretical considerations are confronted with experimental data for nanocrystalline Sm-Fe-N type permanent magnets. (author)

  3. A novel permanent magnetic rail for HTS levitation propulsion system

    International Nuclear Information System (INIS)

    Guo, F.; Tang, Y.; Ren, L.; Li, J.

    2009-01-01

    The Halbach Array has a characteristic advantage that the spatial fundamental field is canceled on one side of the array while the field intensity on the other side is enhanced. So this array could be used in the design of high temperature superconducting permanent magnetic levitation rail to improve the surface magnetic field and levitation force. This paper compared the surface magnetic field of the Halbach Array rail and two conventional levitation rails at first. Then proposed the potential advantages of Halbach Array applied in permanent magnetic rail system. But the Halbach Array rail is mechanical instability. An novel improved Halbach Array rail is proposed in this paper. The new structure combined the advantages of traditional structure and Halbach Array structure, solved the problem of mechanical instability, and carried on the advantage of Halbach Array on the magnetic field distribution at the same time.

  4. Nonuniform radiation damage in permanent magnet quadrupoles.

    Science.gov (United States)

    Danly, C R; Merrill, F E; Barlow, D; Mariam, F G

    2014-08-01

    We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL's pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

  5. Nonuniform radiation damage in permanent magnet quadrupoles

    International Nuclear Information System (INIS)

    Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G.

    2014-01-01

    We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components

  6. Nonuniform radiation damage in permanent magnet quadrupoles

    Energy Technology Data Exchange (ETDEWEB)

    Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

    2014-08-15

    We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

  7. 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.

  8. Permanent multipole magnets with adjustable strength

    International Nuclear Information System (INIS)

    Halbach, K.

    1983-01-01

    Preceded by a short discussion of the motives for using permanent magnets in accelerators, a new type of permanent magnet for use in accelerators is presented. The basic design and most important properties of a quadrople will be described that uses both steel and permanent magnet material. The field gradient produced by this magnet can be adjusted without changing any other aspect of the field produced by this quadrupole. The generalization of this concept to produce other multipole fields, or combination of multipole fields, will also be presented

  9. Permanent multipole magnets with adjustable strength

    International Nuclear Information System (INIS)

    Halbach, K.

    1983-03-01

    Preceded by a short discussion of the motives for using permanent magnets in accelerators, a new type of permanent magnet for use in accelerators is presented. The basic design and most important properties of a quadrupole will be described that uses both steel and permanent magnet material. The field gradient produced by this magnet can be adjusted without changing any other aspect of the field produced by this quadrupole. The generalization of this concept to produce other multipole fields, or combination of multipole fields, will also be presented

  10. Permanent magnet materials and their application

    International Nuclear Information System (INIS)

    Campbell, P.

    1994-01-01

    Permanent magnets are of great industrial importance in industrial drives, consumer products, computers, and automobiles. Since 1970, new classes of magnet materials have been developed. This book reviews the older and newer materials and is presented as a comprehensive design text for permanent magnets and their applications. After an initial chapter on the fundamentals of magnetism, the author discusses magnetic physics considerations specific to permanent magnets and describes the fabrications and characteristics of commercial materials: alnico, samarium-cobalt, ferrite, and neodymium-iron-boron. Thermal stability, magnet design procedures, magnetic field analysis methods, and measurement methods are discussed in subsequent chapters, followed by a concluding chapter reviewing commercial and industrial products that use permanent magnets. The chapter on thermal properties of magnet materials is of particular interest, bringing together information not readily found elsewhere. The review of applications is also deserving of attention, specifically the sections on motors and actuators. Although particle accelerator applications are discussed, the use of permanent magnet sextuples in modern ECR ion sources is not mentioned

  11. Magnetizing of permanent magnet using HTS bulk magnet

    International Nuclear Information System (INIS)

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

    2011-01-01

    A demagnetized Nd-Fe-B permanent magnet was scanned just above the magnetic pole containing 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 magnetic plates inversely with various overlap distances between the tracks of the HTS 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. (author)

  12. Stabilization of magnet assemblies of permanent magnet sodium flowmeters used in fast breeder reactors

    Energy Technology Data Exchange (ETDEWEB)

    Rajan, K.K., E-mail: kkrajan@igcar.gov.in; Vijayakumar, G.

    2014-08-15

    Highlights: • Stabilization procedure for ALNICO-5 permanent magnet material is evolved. • Effect of time and temperature on ALNICO-5 assembly is determined. • Suitability of ALNICO-5 flowmeters at high temperatures is established. • Temperature coefficient of flux density is determined. - Abstract: Permanent magnet flow meters (PMFMs) are used to measure the sodium flow in sodium cooled Fast Breeder Reactor Circuits. Prototype fast breeder reactor (PFBR) which is under construction at Kalpakkam is a 500 MWe, sodium cooled, pool type reactor. Sodium flow measurement in various loops of the reactor is of prime importance from operational and safety point of view. To measure the flow of electrically conducting liquid sodium, in primary and secondary circuit pipe lines of PFBR, permanent magnet flow meters are used. PMFM is a non-invasive device, which works on the principle of generation of motional EMF by magnetic forces exerted on the charges in a moving conductor. Flowmeters of different pipe sizes ranging from 10 mm to 200 mm pipe diameter are required for PFBR. Long term performance of the flowmeters mainly depends on stability of permanent magnets used in flowmeters to generate constant magnetic field in stainless steel (SS) pipes. This paper describes the effects of time and temperature on permanent magnet assemblies made of ALNICO-V used in PFBR flowmeters. The stabilization methodology for ALNICO-V permanent magnet assemblies is evolved and established. Loss of magnetic field strength with respect to time and temperatures is determined by experiments and found negligible.

  13. 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.

  14. Static devices with new permanent magnets

    International Nuclear Information System (INIS)

    Chavanne, J.; Laforest, J.; Pauthenet, R.

    1987-01-01

    The high remanence and coercivity of the new permanent magnet materials are of special interest in the static applications. High ordering temperature and are uniaxial anisotropy at the origin of their good permanent magnet properties are obtained in rare earth-transition metal compounds. Binary SmCo/sub 5/ and Sm/sub 2/Co/sub 17/ and ternary Nd/sub 2/Fe/sub 14/B compounds are the basis materials of the best permanent magnets. new concepts of calculations of static devices with these magnets can be applied: the magnetization can be considered as ridig, the density of the surface Amperian current is constant, the relative permeability is approximately 1 and the induction calculations are linear. Examples of hexapoles with Sm-Co and NdFeB magnets are described and the performances are compared. The problems of temperature behavior and corrosion resistance are underlined

  15. 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.

  16. Superconducting Electric Machine with Permanent Magnets and Bulk HTS Elements

    Science.gov (United States)

    Levin, A. V.; Vasich, P. S.; Dezhin, D. S.; Kovalev, L. K.; Kovalev, K. L.; Poltavets, V. N.; Penkin, V. T.

    Theoretical methods of calculating of two-dimensional magnetic fields, inductive parameters and output characteristics of the new type of high-temperature superconducting (HTS) synchronous motors with a composite rotor are presented. The composite rotor has the structure containing HTS flat elements, permanent magnets and ferromagnetic materials. The developed calculation model takes into account the concentrations and physical properties of these rotor elements. The simulation results of experimental HTS motor with a composite rotor are presented. The application of new type of HTS motor in different constructions of industrial high dynamic drivers is discussed.

  17. Filtering peripheral high temperature electrons in a cylindrical rf-driven plasmas by an axisymmetric radial magnetic field

    Directory of Open Access Journals (Sweden)

    Hikaru Akahoshi

    2018-03-01

    Full Text Available High temperature electrons generated near a radial wall of a cylindrical source tube in a radiofrequency (rf inductively-coupled plasma is filtered by an axisymmetric radial magnetic field formed near the source exit by locating annular permanent magnets, where the axial magnetic field strength in the radially central region is fairly uniform inside the source tube and is close to zero near the source exit. The source is operated at 3 mTorr in argon and the rf antenna is powered by a 13.56 MHz and 400 W rf generator. Measurement of electron energy probability functions shows the presence of the peripheral high temperature electrons inside the source, while the temperature of the peripheral electrons downstream of the source is observed to be reduced.

  18. Filtering peripheral high temperature electrons in a cylindrical rf-driven plasmas by an axisymmetric radial magnetic field

    Science.gov (United States)

    Akahoshi, Hikaru; Takahashi, Kazunori; Ando, Akira

    2018-03-01

    High temperature electrons generated near a radial wall of a cylindrical source tube in a radiofrequency (rf) inductively-coupled plasma is filtered by an axisymmetric radial magnetic field formed near the source exit by locating annular permanent magnets, where the axial magnetic field strength in the radially central region is fairly uniform inside the source tube and is close to zero near the source exit. The source is operated at 3 mTorr in argon and the rf antenna is powered by a 13.56 MHz and 400 W rf generator. Measurement of electron energy probability functions shows the presence of the peripheral high temperature electrons inside the source, while the temperature of the peripheral electrons downstream of the source is observed to be reduced.

  19. Cylindrical Hall Thrusters with Permanent Magnets

    International Nuclear Information System (INIS)

    Raitses, Yevgeny; Merino, Enrique; Fisch, Nathaniel J.

    2010-01-01

    The use of permanent magnets instead of electromagnet coils for low power Hall thrusters can offer a significant reduction of both the total electric power consumption and the thruster mass. Two permanent magnet versions of the miniaturized cylindrical Hall thruster (CHT) of different overall dimensions were operated in the power range of 50W-300 W. The discharge and plasma plume measurements revealed that the CHT thrusters with permanent magnets and electromagnet coils operate rather differently. In particular, the angular ion current density distribution from the permanent magnet thrusters has an unusual halo shape, with a majority of high energy ions flowing at large angles with respect to the thruster centerline. Differences in the magnetic field topology outside the thruster channel and in the vicinity of the channel exit are likely responsible for the differences in the plume characteristics measured for the CHTs with electromagnets and permanent magnets. It is shown that the presence of the reversing-direction or cusp-type magnetic field configuration inside the thruster channel without a strong axial magnetic field outside the thruster channel does not lead to the halo plasma plume from the CHT.

  20. The history of permanent magnet materials

    International Nuclear Information System (INIS)

    Livingston, J.D.

    1990-01-01

    Permanent-magnet materials play a large and growing, but largely unseen, role in today's technology. Many common devices in the home and elsewhere, including appliances, computers and printers, contain permanent-magnet motors and actuators. The growth of applications for permanent magnets results in large part from the improvements in magnetic properties, which allow the engineer to design smaller, lighter and more efficient devices. The properties of the greatest technological interest are remanence, coercivity and maximum energy product. All are non-equilibrium and high structure-sensitive. Coercivity is particularly sensitive to microstructure, while remanence is sensitive to texture (crystallographic alignment). The energy product depends on both coercivity and remanence. The more than one hundredfold increase in the available energy product in this century, and the corresponding amount of magnet required for a specific application, are shown

  1. Radiation Shielding Utilizing A High Temperature Superconducting Magnet

    Data.gov (United States)

    National Aeronautics and Space Administration — Project objective is to evaluate human radiation protection and architecture utilizing existing superconducting magnet technology while attempting to significantly...

  2. Characterizing permanent magnet blocks with Helmholtz coils

    Science.gov (United States)

    Carnegie, D. W.; Timpf, J.

    1992-08-01

    Most of the insertion devices to be installed at the Advanced Photon Source will utilize permanent magnets in their magnetic structures. The quality of the spectral output is sensitive to the errors in the field of the device which are related to variations in the magnetic properties of the individual blocks. The Advanced Photon Source will have a measurement facility to map the field in the completed insertion devices and equipment to test and modify the magnetic strength of the individual magnet blocks. One component of the facility, the Helmholtz coil permanent magnet block measurement system, has been assembled and tested. This system measures the total magnetic moment vector of a block with a precision better than 0.01% and a directional resolution of about 0.05°. The design and performance of the system will be presented.

  3. Dovetail spoke internal permanent magnet machine

    Science.gov (United States)

    Alexander, James Pellegrino [Ballston Lake, NY; EL-Refaie, Ayman Mohamed Fawzi [Niskayuna, NY; Lokhandwalla, Murtuza [Clifton Park, NY; Shah, Manoj Ramprasad [Latham, NY; VanDam, Jeremy Daniel [West Coxsackie, NY

    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.

  4. Analysis of a spherical permanent magnet actuator

    International Nuclear Information System (INIS)

    Wang, J.; Jewell, G.W.; Howe, D.

    1997-01-01

    This paper describes a new form of actuator with a spherical permanent magnet rotor and a simple winding arrangement, which is capable of a high specific torque by utilizing a rare-earth permanent magnet. The magnetic-field distribution is established using an analytical technique formulated in spherical coordinates, and the results are validated by finite element analysis. The analytical field solution allows the prediction of the actuator torque and back emf in closed forms. In turn, these facilitate the characterization of the actuator and provide a firm basis for design optimization, system dynamic modeling, and closed-loop control law development. copyright 1997 American Institute of Physics

  5. High temperature magnetic properties of nanocrystalline Sn0 ...

    Indian Academy of Sciences (India)

    Administrator

    hysteresis loop at 300 K temperature, which reflects its ferromagnetic behaviour. We confirmed ... obtained by doping magnetic transition elements such as. Mn, Fe and .... factor to account for particle shapes, λ = 1⋅5406 Å the wavelength of ...

  6. Design and construction of permanent magnetic gears

    DEFF Research Database (Denmark)

    Jørgensen, Frank Thorleif

    /l]. Measurement from this gear has resulted in a measured total torque density of 23 [Nm/l]. Mechanical versions of this gear type are found with total torque density in the 16 to 31 [Nm/l] range. The third and last gear technology that is investigated is a gear that reminds of a planetary gear. Research shows......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 verified with models developed in this project. Present technological status for magnetic gears is introduced...

  7. High-field permanent-magnet structures

    International Nuclear Information System (INIS)

    Leupoid, H.A.

    1989-01-01

    This patent describes a permanent magnet structure. It comprises an azimuthally circumscribed section of a hollow hemispherical magnetic flux source, the magnetic orientation in the section with respect to the polar axis being substantially equal to twice the polar angle, a superconducting planar sheet abutting one flat face of the section along a longitudinal meridian, and at least one other planar sheet of selected material abutting another flat face of the section and perpendicular to the first-mentioned sheet

  8. Superconducting permanent magnets and their application in magnetic levitation

    International Nuclear Information System (INIS)

    Schultz, L.; Krabbes, G.; Fuchs, G.; Pfeiffer, W.; Mueller, K.H.

    2002-01-01

    Superconducting permanent magnets form a completely new class of permanent magnets. Of course, they must be cooled to 77 K or below. At very low temperatures (24 K) their magnetization can be a factor of 10 higher than that of the best conventional magnets, providing magnetic forces and energies which are up to two orders of magnitude higher. These new supermagnets became only recently available by the extreme improvement of the quality of melt-textured massive YBa 2 Cu 3 O x samples. Besides having a high magnetization, these superconducting permanent magnets can freeze in any given magnetic field configuration allowing completely new applications like superconducting transport systems or superconducting magnetic bearings. (orig.)

  9. Magnetic shielding for coreless linear permanent magnet motors

    NARCIS (Netherlands)

    Pluk, K.J.W.; Jansen, J.W.; Lomonova, E.

    2013-01-01

    This paper concerns the local reduction of the magnetic flux density by means of magnetic shielding. Using a spatial frequency description, a 2-D semi-analytical periodic model is obtained for a coreless single-sided linear permanent magnet motor. The magnetic shield is included in the modeling

  10. Self-propagating high temperature synthesis and magnetic ...

    Indian Academy of Sciences (India)

    Unknown

    phase composition, microstructure and magnetic properties of the combustion products. The effect ... The size and shapes of the ... Figure 3 shows the effect of combustion temperature on ... ducts at 1200°C are too hard to be ground easily and.

  11. Development of cryogenic permanent magnet undulator

    International Nuclear Information System (INIS)

    Hara, Toru; Tanaka, Takashi; Shirasawa, Katsutoshi; Kitamura, Hideo; Bizen, Teruhiko; Seike, Takamitsu; Marechal, Xavier; Tsuru, Rieko; Iwaki, Daisuke

    2005-01-01

    A short period undulator increases not only the photon energy of undulator radiation, but also the brilliance due to its increased number of undulator periods. As a result, brilliant undulator radiation becomes available in the photon energy range, which is currently covered by wigglers. In order to develop a short period undulator, high performance magnets are indispensable and superconductive undulators have been actively investigated in recent years. In this paper, however, we propose a new approach, so called a cryogenic permanent magnet undulator using NdFeB magnets at the temperatures around 150 K. The current status of this cryogenic permanent magnet undulator development at SPring-8 is presented including the results of the magnetic field measurements on a prototype undulator. (author)

  12. Regulation of fields excited by permanent magnets

    International Nuclear Information System (INIS)

    Savchenko, I.S.

    1989-01-01

    Two methods of fast regulation of fields excited by permanent magnets in salient-pole electron-optical lenses are described: 1)the hybrid method realized using the additional electromagnet introduced to a magnetic chain sequentially its field being composed or substracted with magnetosolid exciter field; 2)the method with saturation of a part of a magnetic circuit, with saturation being achievable at the begining or in the end of a regulation cycle. In the second method it is proposed to direct orthogonally the main flux excited by permanent magnets and the flux in the saturated part of the magnetic circuit excited using an electromagnet. It is shown that the second method allows one to reduce the required ampere-coils by more than an order as compared to the first method at one and the same regulation range and other equal conditions. The frequency of field regulation in the experimental mock-up was 10 kHz. 3 refs.; 2 figs

  13. High temperature magnetic susceptibility of the Nb-H system

    International Nuclear Information System (INIS)

    Welter, J.-M.

    1983-01-01

    The magnetic susceptibility chi(T,x) of various NbHsub(x) specimens with 0 - 5 to 1.25 x 10 - 5 cm 3 g - 1 in this hydrogen concentration range and exhibits a marked break at x approximately 0.6. An estimate of the Pauli paramagnetic spin susceptibility chisub(P) for the two limiting concentrations allowed the evaluation of the orbital paramagnetic susceptibility chisub(O). For x = 0 and x approximately 0.8 the values of chisub(P) are 1.05 x 10 - 5 cm 3 g - 1 and 0.39 x 10 - 5 cm 3 g - 1 respectively and the values of chisub(O) are 1.73 x 10 - 5 cm 3 g - 1 and 1.08 x 10 - 5 cm 3 g - 1 respectively. The magnetic susceptibility decreases by approximately 10% on going from the concentrated solid solution to the monohydride. (Auth.)

  14. Time dependence of magnetization of high temperature superconductors

    International Nuclear Information System (INIS)

    Larkin, A.I.; Geshkenbein, V.B.

    1988-10-01

    Magnetization of high T c superconductors logarithmically decreases with time. There is a maximum in the temperature dependence of the coefficient at this logarithm. If one assumes that there do exist two kinds of pinning centers, then this dependence can be described in the Anderson theory of thermal creeps of Abrikosov's vortices. The temperature dependence of the critical current is also discussed. (author). 23 refs

  15. Magnet coils made from high-temperature superconductor

    International Nuclear Information System (INIS)

    Jenkins, R.G.; Yang, M.; Grovenor, C.R.M.; Goringe, M.J.

    1996-01-01

    We review the progress we have made in constructing HTS coils and report our latest results. Also we describe the cryogen-free operation of one of our HTS coils cooled to 55 K using a Stirling cycle cryocooler. Lastly, we describe how 4 Oxford coils are being used in a project to investigate the controllability of HTS magnets in applications such as ''maglev'' suspension systems. We briefly report the initial findings of this work and describe developments in progress. (orig.)

  16. Progress in application of high temperature superconductor in tokamak magnets

    Czech Academy of Sciences Publication Activity Database

    Gryaznevich, M.; Svoboda, V.; Stöckel, Jan; Sykes, A.; Sykes, N.; Kingham, D.; Hammond, G.; Apte, P.; Todd, T.N.; Ball, S.; Chappell, S.; Melhem, D.; Ďuran, Ivan; Kovařík, Karel; Grover, O.; Markovič, T.; Odstrčil, M.; Odstrčil, T.; Šindlery, A.; Vondrášek, G.; Kocman, J.; Lilley, M.K.; de Grouchy, P.; Kim, H.-T.

    2013-01-01

    Roč. 88, 9-10 (2013), s. 1593-1596 ISSN 0920-3796. [Symposium on Fusion Technology (SOFT-27)/27./. Liège, 24.09.2012-28.09.2012] Institutional support: RVO:61389021 Keywords : tokamaks * HTS * magnet s Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.149, year: 2013 http://www.sciencedirect.com/science/article/pii/S0920379613001117#

  17. Analysis of Hall Probe Precise Positioning with Cylindrical Permanent Magnet

    International Nuclear Information System (INIS)

    Belicev, P.; Vorozhtsov, A.S.; Vorozhtsov, S.B.

    2007-01-01

    Precise positioning of a Hall probe for cyclotron magnetic field mapping, using cylindrical permanent magnets, was analyzed. The necessary permanent magnet parameters in order to achieve ±20 μm position precision, were determined. (author)

  18. Magnetization studies in high temperature and conventional superconductors

    International Nuclear Information System (INIS)

    Grover, A.K.; Chaddah, P.

    1991-01-01

    In this paper, the authors state the contemporary view of the physical basis of a celebrated phenomenological model for hard superconductors. The authors highlight the qualitative and general predictions of this model relevant to various magnetic measurements. The authors give prescriptions to correlate data of different experiments with the predictions of the model with the intention of extracting information on material parameters, like J c (H), pinning potential, etc. These prescriptions will be illustrated with the data on both conventional and HTSC superconductors. The correlation of these data with the predictions of the model underscores the similarity in behaviour between the two classes of hard superconductors

  19. Initial evolution of nonlinear magnetic islands in high temperature plasmas

    International Nuclear Information System (INIS)

    Kotschenreuther, M.

    1988-06-01

    The evolution of nonlinear magnetic islands is computed in the kinetic collisionality regime called the semicollisional regime, which is appropriate to present fusion confinement devices. Realistic effects are included, such as the presence of small external field errors, radial electric fields, and omega. When present simultaneously, these effects can greatly change the stability of small amplitude nonlinear islands. Islands with Δ' > O can sometimes be prevented from growing to macroscopic size; it is also possible to produce moderate mode-number nonlinear instabilities in the plasma edge. Furthermore, island growth can be prevented by application of external fields with suitably chosen amplitude and frequency

  20. High-temperature magnetoresistance study of a magnetic tunnel junction

    International Nuclear Information System (INIS)

    Chen, D.C.; Yao, Y.D.; Chen, C.M.; Hung, James; Chen, Y.S.; Wang, W.H.; Chen, W.C.; Kao, M.J.

    2006-01-01

    The thermal stability and the spin transportation phenomenon at room temperature and 140 deg. C of a series of magnetic tunneling junctions with the structure of bottom electrode/PtMn/Pinned layer/ AlO x /CoFe/NiFe/top electrode have been investigated. The MR ratio decreases from 33.5% at room temperature to 29% at 140 deg. C. The MR ratio at room temperature increases roughly 0.8% after thermal treatment at temperatures above 60 deg. C. This is related to the thermal relaxation of the strains existing in the samples

  1. Tuning permanent magnets with adjustable field clamps

    International Nuclear Information System (INIS)

    Schermer, R.I.

    1987-01-01

    The effective length of a permanent-magnet assembly can be varied by adjusting the geometrical parameters of a field clamp. This paper presents measurements on a representative dipole and quadrupole as the field clamp is withdrawn axially or radially. The detailed behavior depends upon the magnet multipolarity and geometry. As a rule-of-thumb, a 3-mm-thick iron plate placed at one end plane of the magnet will shorten the length by one-third of the magnet bore radius

  2. A conceptual design of high-temperature superconducting isochronous cyclotron magnet

    International Nuclear Information System (INIS)

    Jiao, F.; Tang, Y.; Li, J.; Ren, L.; Shi, J.

    2011-01-01

    A design of High-temperature superconducting (HTS) isochronous cyclotron magnet is proposed. The maximum magnetic field of cyclotron main magnet reaches 3 T. Laying the HTS coil aboard the magnetic pole will raise the availability of the magnetic Field. Super-iron structure can provide a high uniformity and high gradient magnetic field. Super-iron structure can raise the availability of the HTS materials. Along with the development of High-temperature superconducting (HTS) materials, the technology of HTS magnet is becoming increasingly important in the Cyclotron, which catches growing numbers of scholars' attentions. Based on the analysis of the problems met in the process of marrying superconducting materials with ferromagnetic materials, this article proposes a design of HTS isochronous cyclotron magnet. The process of optimization of magnet and the methods of realizing target parameters are introduced after taking finite element software as analyzing tools.

  3. Tubular permanent magnet actuators: cogging forces characterization

    NARCIS (Netherlands)

    Paulides, J.J.H.; Janssen, J.L.G.; Encica, L.; Lomonova, E.A.

    2009-01-01

    Tubular permanent magnet actuators are evermore used in demanding industrial and automotive applications. However, these actuators can suffer from large cogging forces, which have a destabilizing effect on the servo control system and compromise position and speed control accuracy. This paper

  4. resonant inverter supplied interior permanent magnet (ipm)

    African Journals Online (AJOL)

    user

    [5] Zhenyue Hong, “DC-voltage link resonant inverters”, Department of Electrical and. Electronic Engineering University of. Canterbury, New Zealand. [6] Kalyan Kumar Halder, Naruttam Kumar Roy and B.C. Ghosh, “Position Sensorless. Control for an Interior Permanent Magnet. Synchronous Motor SVM Drive with ANN.

  5. 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.

  6. Constant force linear permanent magnet actuators

    NARCIS (Netherlands)

    Paulides, J.J.H.; Encica, L.; Meessen, K.J.; Lomonova, E.A.

    2009-01-01

    In applications, such as vibration isolation, gravity compensation, pick-and-place machines, etc., there is a need for (long-stroke) passive constant force actuators combined with tubular permanent magnet actuators to minimize the power consumption, hence, passively counteract the gravitational

  7. 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, coinci...

  8. Magnetic forces between arrays of cylindrical permanent magnets

    Czech Academy of Sciences Publication Activity Database

    Vokoun, David; Tomassetti, G.; Beleggia, M.; Stachiv, Ivo

    2011-01-01

    Roč. 323, č. 1 (2011), s. 55-60 ISSN 0304-8853 R&D Projects: GA ČR(CZ) GA101/09/0702 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetism * permanent magnets Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.780, year: 2011

  9. 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...

  10. A permanent magnet system for Kibble balances

    Science.gov (United States)

    Li, Shisong; Bielsa, Franck; Stock, Michael; Kiss, Adrien; Fang, Hao

    2017-10-01

    The magnet is one of the fundamental elements in Kibble balances. The Kibble balance group at the Bureau International des Poids et Mesures (BIPM) proposed a permanent magnet with a radial field, which has been widely employed in other Kibble balance experiments. In this paper, we discuss a different method of operation for the BIPM-type magnet, i.e. only the lower half of the magnetic circuit is closed. The merit of such a magnet is its convenience for opening the air gap and adjusting the coil. A disadvantage is that it can yield a lower and sloped magnetic field profile with less shielding. In the approach described, high permeability yokes are used to flatten the magnetic profile, which has proven to be a novel and convenient approach for removing the nonuniformity of the magnetic profile due to magnet magnetization asymmetries. The performance of the half-closed BIPM magnet is evaluated using experimental measurements. The results show that the half-closed magnetic circuit retains most of the main features of the fully-closed magnet and is a good option for the early stages of Kibble balance operations. In addition, the profile change due to the coil current is predicted and experimentally verified with a bifilar coil. Related systematic effects are discussed for the Planck constant measurement.

  11. 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...... the synchronous machine requires knowledge of the rotor shaft position due to the synchronous and undamped nature of the machine. The rotor position may be measured using a mechanical sensor, but the sensor reduces reliability and adds cost to the system and for this reason sensorless control methods started...... 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...

  12. 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.

  13. Permanent-magnet-less synchronous reluctance system

    Science.gov (United States)

    Hsu, John S

    2012-09-11

    A permanent magnet-less synchronous system includes a stator that generates a magnetic revolving field when sourced by an alternating current. An uncluttered rotor is disposed within the magnetic revolving field and spaced apart from the stator to form an air gap relative to an axis of rotation. The rotor includes a plurality of rotor pole stacks having an inner periphery biased by single polarity of a north-pole field and a south-pole field, respectively. The outer periphery of each of the rotor pole stacks are biased by an alternating polarity.

  14. Dysprosium-free melt-spun permanent magnets

    International Nuclear Information System (INIS)

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

    2014-01-01

    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 Nd 2 Fe 14 B 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. (paper)

  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. Investigation of Anisotropic Bonded Magnets in Permanent Magnet Machine Applications

    Science.gov (United States)

    Khazdozian, H. A.; McCall, S. K.; Kramer, M. J.; Paranthaman, M. P.; Nlebedim, I. C.

    Rare earth elements (REE) provide the high energy product necessary for permanent magnets, such as sintered Nd2Fe14B, in many applications like wind energy generators. However, REEs are considered critical materials due to risk in their supply. To reduce the use of critical materials in permanent magnet machines, the performance of anisotropic bonded NdFeB magnets, aligned under varying magnetic field strength, was simulated using 3D finite element analysis in a 3MW direct-drive permanent magnet generator (DDPMG), with sintered N42 magnets used as a baseline for comparison. For direct substitution of the anisotropic bonded magnets, approximately 85% of the efficiency of the baseline model was achieved, irrespective of the alignment field. The torque and power generation of the DDPMG was not found to vary significantly with increase in the alignment field. Finally, design changes were studied to allow for the achievement of rated torque and power with the use of anisotropic bonded magnets, demonstrating the potential for reduction of critical materials in permanent magnets for renewable energy applications. This work was supported by the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office.

  17. Variable high gradient permanent magnet quadrupole (QUAPEVA)

    Science.gov (United States)

    Marteau, F.; Ghaith, A.; N'Gotta, P.; Benabderrahmane, C.; Valléau, M.; Kitegi, C.; Loulergue, A.; Vétéran, J.; Sebdaoui, M.; André, T.; Le Bec, G.; Chavanne, J.; Vallerand, C.; Oumbarek, D.; Cosson, O.; Forest, F.; Jivkov, P.; Lancelot, J. L.; Couprie, M. E.

    2017-12-01

    Different applications such as laser plasma acceleration, colliders, and diffraction limited light sources require high gradient quadrupoles, with strength that can reach up to 200 T/m for a typical 10 mm bore diameter. We present here a permanent magnet based quadrupole (so-called QUAPEVA) composed of a Halbach ring and surrounded by four permanent magnet cylinders. Its design including magnetic simulation modeling enabling us to reach 201 T/m with a gradient variability of 45% and mechanical issues are reported. Magnetic measurements of seven systems of different lengths are presented and confirmed the theoretical expectations. The variation of the magnetic center while changing the gradient strength is ±10 μm. A triplet of QUAPEVA magnets is used to efficiently focus a beam with large energy spread and high divergence that is generated by a Laser Plasma Acceleration source for a free electron laser demonstration and has enabled us to perform beam based alignment and control the dispersion of the beam.

  18. 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.

  19. Permanent-magnet switched-flux machine

    Science.gov (United States)

    Trzynadlowski, Andrzej M.; Qin, Ling

    2010-01-12

    A permanent-magnet switched-flux (PMSF) device has a ferromagnetic outer stator mounted to a shaft about a central axis extending axially through the PMSF device. Pluralities of top and bottom stator poles are respectively mounted in first and second circles, radially outwardly in first and second transverse planes extending from first and second sections of the central axis adjacent to an inner surface of the ferromagnetic outer stator. A ferromagnetic inner rotor is coupled to the shaft and has i) a rotor core having a core axis co-axial with the central axis; and ii) first and second discs having respective outer edges with first and second pluralities of permanent magnets (PMs) mounted in first and second circles, radially outwardly from the rotor core axis in the first and second transverse planes. The first and second pluralities of PMs each include PMs of alternating polarity.

  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. Magnetic forces between arrays of cylindrical permanent magnets

    DEFF Research Database (Denmark)

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

    2011-01-01

    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...

  2. 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

  3. Finite element analysis of permanent magnet motors

    International Nuclear Information System (INIS)

    Boglietti, A.; Chiampi, M.; Tartaglia, M.; Chiarabaglio, D.

    1989-01-01

    The analysis of permanent magnet D.C. brushless motors, supplied by current control inverters, is developed employing a finite element package tailored for such devices. The study is devoted to predicting the performance of a set of four poles machines, under different operating conditions (no-load, rated load). The over-load conditions are also considered including the saturation effect. Moreover the influence of such design parameters, as the tooth shape and the number of magnet segments, is investigated. Computed results are found in satisfactory agreement with experimental ones

  4. Automatic design of permanent magnet coupling

    International Nuclear Information System (INIS)

    Yonnet, J.-P.; Pandele, P.; Coutel, C.; Wurtz, F.

    1998-01-01

    Up to now, two main methods have been used to design permanent magnet couplings : finite element calculation, and analytical expressions of the forces between the magnets. The two methods use the same starting point, the permanent magnet coupling dimensions. The calculated parameters are the forces and the torques. The optimization of the couplings shape is generally done by using different curves describing torque variations as a function of the different geometrical parameters. We have developed a very new approach solving the reverse problem. Choosing the value of the torque, the airgap and an optimization criterium, the new method automatically calculates the size of the magnets and the ideal number of poles. It is based on a software, PASCOSMA, using an analytical model of the coupling which can be eventually corrected by a finite element method like FLUX2D. The coupling optimization is automatically made, keeping the parameters between predefined values. For a given application, it is very easy to obtain the best design, for example with the minimum magnet volume. (orig.)

  5. Forces between permanent magnets: experiments and model

    International Nuclear Information System (INIS)

    González, Manuel I

    2017-01-01

    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. (paper)

  6. Experience with the SLC permanent magnet multipoles

    International Nuclear Information System (INIS)

    Gross, G.; Spencer, J.

    1994-06-01

    Permanent magnets have been used in the SLC Damping Rings and their injection and extraction lines since 1985. Recent upgrades of the DR vacuum chambers provided an opportunity to check DR magnets prior to higher beam current operation. Several PM sextupoles downstream of the injection kickers in the electron ring had exceeded their thermal stabilization values of 80 degrees C and some showed serious mechanical deformations and radiation >1 R at contact. We discuss our observations, measurements and a few inexpensive modifications that should improve these magnets under such conditions. A new, block matching algorithm allowed us to use magnet blocks that had been considered unusable because of very different remament field strengths and easy axis errors

  7. 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.

  8. Low temperature superconductor and aligned high temperature superconductor magnetic dipole system and method for producing high magnetic fields

    Science.gov (United States)

    Gupta, Ramesh; Scanlan, Ronald; Ghosh, Arup K.; Weggel, Robert J.; Palmer, Robert; Anerella, Michael D.; Schmalzle, Jesse

    2017-10-17

    A dipole-magnet system and method for producing high-magnetic-fields, including an open-region located in a radially-central-region to allow particle-beam transport and other uses, low-temperature-superconducting-coils comprised of low-temperature-superconducting-wire located in radially-outward-regions to generate high magnetic-fields, high-temperature-superconducting-coils comprised of high-temperature-superconducting-tape located in radially-inward-regions to generate even higher magnetic-fields and to reduce erroneous fields, support-structures to support the coils against large Lorentz-forces, a liquid-helium-system to cool the coils, and electrical-contacts to allow electric-current into and out of the coils. The high-temperature-superconducting-tape may be comprised of bismuth-strontium-calcium-copper-oxide or rare-earth-metal, barium-copper-oxide (ReBCO) where the rare-earth-metal may be yttrium, samarium, neodymium, or gadolinium. Advantageously, alignment of the large-dimension of the rectangular-cross-section or curved-cross-section of the high-temperature-superconducting-tape with the high-magnetic-field minimizes unwanted erroneous magnetic fields. Alignment may be accomplished by proper positioning, tilting the high-temperature-superconducting-coils, forming the high-temperature-superconducting-coils into a curved-cross-section, placing nonconducting wedge-shaped-material between windings, placing nonconducting curved-and-wedge-shaped-material between windings, or by a combination of these techniques.

  9. Discussions on performance of two types of permanent multipole magnets

    International Nuclear Information System (INIS)

    Xu Jianming; Xu Qing; Yin Zhaosheng

    1987-01-01

    The field distributions of MMD type and MW type multipole permanent magnets are calculated by means of programme POISCR and the results are summarized and discussed in this paper. The resutls show that, considering the nonlinearity of the real demagnetization curve of permanent magnet material, the field distributions of both types of permanent magnets with the same aperature are about the same but the field strength of MW type magnet with soft iron shield is higher than that of MMD type magnet

  10. A rotary permanent magnet magnetic refrigerator based on AMR cycle

    International Nuclear Information System (INIS)

    Aprea, C.; Cardillo, G.; Greco, A.; Maiorino, A.; Masselli, C.

    2016-01-01

    Magnetic refrigeration is an emerging, environment-friendly technology based on a magnetic solid that acts as a refrigerant by magneto-caloric effect (MCE). The reference cycle for magnetic refrigeration is AMR (Active Magnetic Regenerative refrigeration). In order to demonstrate the potential of magnetic refrigeration to provide useful cooling in the near room temperature range, a novel Rotary Permanent Magnet Magnetic Refrigerator (RPMMR) is described in this paper. Gadolinium has been selected as magnetic refrigerant and demineralized water has been employed as regenerating fluid. The total mass of gadolinium (1.20 kg), shaped as packed bed spheres, is housed in 8 regenerators. A magnetic system, based on a double U configuration of permanent magnets, provides a magnetic flux density of 1.25 T with an air gap of 43 mm. A rotary vane pump forces the regenerating fluid through the regenerators. The operational principle of the magnetic refrigerator and initial experimental results are reported and analyzed.

  11. Three-dimensional quadrupole lenses made with permanent magnets

    International Nuclear Information System (INIS)

    Ivanov, A.S.

    1984-01-01

    The performance of accelerator systems with quadrupole magnets can be improved by using permanent magnets in quadrupole lenses. This requires better methods for treating the three-dimensional nature of the magnetic fields and the nonlinear characteristics of the magnets. A numerical method is described for simulating three-dimensional magnetic fields and used to analyze quadrupole lenses and doublets with permanent magnets. The results, which are confirmed experimentally, indicate that both the quadrupole magnetic gradient and the effective field length are changed in permanent-magnet quadrupole lenses when the pole lengths and the gap between the lenses are varied while the other characteristics of the magnets remain unchanged

  12. 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

    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...

  13. 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.

  14. Design of permanent magnetic solenoids for REGAE

    International Nuclear Information System (INIS)

    Gehrke, Tim

    2013-10-01

    The Relativistic Electron Gun for Atomic Exploration (REGAE) is a small linear accelerator at DESY in Hamburg, which produces short, low emittance electron bunches. 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.

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

    International Nuclear Information System (INIS)

    Croat, J.J.

    1997-01-01

    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. copyright 1997 American Institute of Physics

  16. Magnetic resonance elastometry using a single-sided permanent magnet

    International Nuclear Information System (INIS)

    Tan, Carl S; Marble, Andrew E; Ono, Yuu

    2012-01-01

    In this paper, we describe a magnetic resonance method of measuring material elasticity using a single-sided magnet with a permanent static field gradient. This method encodes sample velocity in a reciprocal space using Hahn spin-echoes with variable timing. The experimental results show a strong correlation between magnetic resonance signal attenuation and elasticity when an oscillating force is applied on the sample. This relationship in turn provides us with information about the displacement velocity experienced by the sample, which is inversely proportional to Young's modulus. The proposed method shows promise in offering a portable and cost-effective magnetic resonance elastography system. (paper)

  17. Planar permanent magnet multipoles: Measurements and configurations

    International Nuclear Information System (INIS)

    Cremer, T.; Tatchyn, R.

    1995-05-01

    Biplanar arrays of N rectangular permanent magnet (PM) blocks can be used to generate high quality N-pole fields in close proximity to the array axis. In applications featuring small-diameter charged particle beams, N-poles of adequate quality can be realized at relatively low cost using small volumes of PM material. In this paper we report on recent measurements performed on planar PM multipoles, and discuss techniques for improving the field quality of such devices at distances appreciably far away from the axis. Applications to hybrid/PM insertion device designs for linac-driven Free Electron Laser (FEL) operation in the x-ray range are described

  18. Comparison of torque capability of three-phase permanent magnet synchronous motors with different permanent magnet arrangement

    International Nuclear Information System (INIS)

    Stumberger, Bojan; Stumberger, Gorazd; Hadziselimovic, Miralem; Hamler, Anton; Gorican, Viktor; Jesenik, Marko; Trlep, Mladen

    2007-01-01

    The paper presents a comparison of torque capability of three-phase permanent magnet synchronous motors with different permanent magnet arrangement. Motors with the following permanent magnet topologies were accounted for in the comparison: the surface-mounted permanent magnet synchronous motor (SMPMSM), the interior permanent magnet synchronous motor (IPMSM), the permanent magnet-assisted synchronous reluctance motor (PMASRM) and the flux reversal permanent magnet motor (FRPMM). Finite element method analysis is employed to determine the performance of each motor. Calculated performance of four-pole IPMSM determined by finite element method calculation is confirmed with the measurements at nearly constant nominal output power in the range of speed 3000-10,000 rpm

  19. Design of permanent magnet synchronous motor within minimum cost

    OpenAIRE

    Півняк, Геннадій Григорович; Бешта, Олександр Степанович; Фурса, Сергій Григорійович; Neuberger, Nikolaus; Nolle, N.

    2010-01-01

    The article describes design and simulation experience of permanent magnet synchronous motor (PMSM). The design goal is to develop PMSM of the least possible cost. For that purpose the standard induction motor stator was applied as a basic solution and permanent magnets were installed in rotor. Simulation results are presented, the dependence of efficiency and total loss on magnet material mass are obtained. The optimal value of permanent magnets is estimated for the given electric motor frame.

  20. Open questions in the magnetic behaviour of high-temperature superconductors

    International Nuclear Information System (INIS)

    Cohen, L.F.; Jensen, Henrik Jeldtoft

    1997-01-01

    A principally experimental review of vortex behaviour in high-temperature superconductors is presented. The reader is first introduced to the basic concepts needed to understand the magnetic properties of type II superconductors. The concepts of vortex melting, the vortex glass, vortex creep, etc are also discussed briefly. The bulk part of the review relates the theoretical predictions proposed for the vortex system in high temperature superconductors to experimental findings. The review ends with an attempt to direct the reader to those areas which still require further clarification. (author)

  1. 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. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Study of Magnetic Properties on the Corrosion Behavior and Influence of Temperature in Permanent Magnet (Nd-Fe-B) Used in PMSM

    OpenAIRE

    N. Yogal; C. Lehrmann

    2014-01-01

    The use of permanent magnets (PM) is increasing in permanent magnet synchronous machines (PMSM) to fulfill the requirements of high efficiency machines in modern industry. PMSM are widely used in industrial applications, wind power plants and the automotive industry. Since PMSM are used in different environmental conditions, the long-term effect of NdFeB-based magnets at high temperatures and their corrosion behavior have to be studied due to the irreversible loss of magn...

  3. sizing of wind powered axial flux permanent magnet alternator using

    African Journals Online (AJOL)

    user

    2016-10-04

    Oct 4, 2016 ... Keywords: Wind-Power, Axial flux, Axial Flux Permanent Machines (AFPM), Axial Flux Permanent Magnet ... energy for power generation, a high constraint is the .... arrangements as Single-Rotor Single-Stator Structure.

  4. Introduction to the permanent magnet motor market

    Energy Technology Data Exchange (ETDEWEB)

    Sawa, Toshihiro; Hamada, Kaneyuki [Yaskawa Electric Corp. (Japan)

    2000-07-01

    According to the Kyoto summit on global warming (COP3) in December 1997, the green-house gas emission level has to be reduced to 92-94% of the 1990 green-house gas level by the year 2014-2018. This would require conserving energy. An efficient means of achieving this voluntary goal is by employing high-efficiency drives, since motors consume 70% of all electricity for industrial use in Japan. As adjustable speed drives become popular, interior permanent magnet (IPM) motors, lately, have been recognized for high-efficiency performance. Due to the progress in permanent magnet technology combined with modern control methods, especially vector control with and without speed-sensors, the IPM motor is gaining in popularity. Compact size and high-efficiency performance is furthering the IPM motor as the preferred motor in many applications. This paper describes the principle and operation of IPM motors and compares its performance with that of an induction motor. Important features and practical control methods for IPM motors are presented. Various application examples highlighting the advantages of employing an IPM motor system are discussed. The applications include, but are not limited to, machine tools, fans, pumps, elevators, cranes, etc. (orig.)

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

    Science.gov (United States)

    Zheng, J.; Liao, X. L.; Jing, H. L.; Deng, Z. G.; Yen, F.; Wang, S. Y.; Wang, J. S.

    2013-10-01

    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.

  6. In-situ magnetization of NdFeB magnets for permanent magnet machines

    International Nuclear Information System (INIS)

    Chang, L.; Eastham, T.R.; Dawson, G.E.

    1991-01-01

    In-situ magnetizers are needed to facilitate the assembly of permanent magnet machines and to remagnetize the magnets after weakening due to a fault condition. The air-core magnetizer in association with the silicon steel lamination structure of the rotor has advantages over its iron-core counterpart. This novel method has been used to magnetize the NdFeB magnets in a 30-hp permanent magnet synchronous motor. The magnetizing capability for different magnetizer geometries was investigated for the magnetization of NdFeB material. The design, testing, and operation of this magnetizer are reported in this paper

  7. Magnetically nonlinear dynamic model of synchronous motor with permanent magnets

    International Nuclear Information System (INIS)

    Hadziselimovic, Miralem; Stumberger, Gorazd; Stumberger, Bojan; Zagradisnik, Ivan

    2007-01-01

    This paper deals with a magnetically nonlinear two-axis dynamic model of a permanent magnet synchronous motor (PMSM). The geometrical and material properties of iron core and permanent magnets, the effects of winding distribution, saturation, cross-saturation and slotting effects are, for the first time, simultaneously accounted for in a single two-axis dynamic model of a three-phase PMSM. They are accounted for by current- and position-dependent characteristics of flux linkages. These characteristics can be determined either experimentally or by the finite element (FE) computations. The results obtained by the proposed dynamic model show a very good agreement with the measured ones and those obtained by the FE computation

  8. Magnetic Performance of a Nanocomposite Permanent Material

    International Nuclear Information System (INIS)

    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 K 1 (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 K 1 (0). When d and K 1 (0) take 2 nm and 0.7K h , respectively, with K h 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. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  9. Some economic aspects of rare-earth permanent magnets

    International Nuclear Information System (INIS)

    Zijlstra, H.

    1978-01-01

    The commercial feasibility of RE permanent magnets is analyzed in terms of price per unit of magnetostatic energy. The availability of the raw materials is also taken into consideration. The conclusion is that RE magnets are and remain relatively expensive as compared with other permanent magnets, and will find only limited application. (author)

  10. Modeling demagnetization effects in permanent magnet synchronous machines

    NARCIS (Netherlands)

    Kral, C.; Sprangers, R.L.J.; Waarma, J.; Haumer, A.; Winter, O.; Lomonova, E.

    2010-01-01

    This paper presents a permanent magnet model which takes temperature dependencies and demagnetization effects into account. The proposed model is integrated into a magnetic fundamental wave machine model using the model- ing language Modelica. For different rotor types permanent magnet models are

  11. The dynamic behavior of magnetic fluid adsorbed to small permanent magnet in alternating magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Sudo, Seiichi, E-mail: sudo@akita-pu.ac.j [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Asano, Daisaku [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Takana, Hidemasa; Nishiyama, Hideya [Institute of Fluid Science, Tohoku University, Katahira 2-1-1, Aobaku, Sendai 980-8577 (Japan)

    2011-05-15

    The dynamic behavior of a magnetic fluid adsorbed to a small NdFeB permanent magnet subjected to an alternating magnetic field was studied with a high speed video camera system. The directions of alternating magnetic field are parallel and opposite to that of the permanent magnet. It was found that the surface of magnetic fluid responds to the external alternating magnetic field in elongation and contraction with a lot of spikes. Generation of a capillary magnetic fluid jet was observed in the neighbourhood of a specific frequency of alternating field. The effect of gravitational force on surface phenomena of magnetic fluid adsorbed to the permanent magnet was revealed. - Research Highlights: Magnetic fluid of the system responds to alternating magnetic field with higher frequencies. Large-amplitude surface motions of magnetic fluid occur at the specific frequencies of the external field. Capillary jets of magnetic fluid are generated at the natural frequency of the system.

  12. 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.

  13. 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.

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

    International Nuclear Information System (INIS)

    Hajima, Ryoichi

    1995-01-01

    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

  15. Magnetostatic interactions and forces between cylindrical permanent magnets

    International Nuclear Information System (INIS)

    Vokoun, David; Beleggia, Marco; Heller, Ludek; Sittner, Petr

    2009-01-01

    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.

  16. 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

    2017-10-01

    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.

  17. Control of permanent magnet synchronous motors

    CERN Document Server

    Vaez-Zadeh, Sadegh

    2018-01-01

    This is the first comprehensive, coherent, and up-to-date book devoted solely to the control of permanent magnet synchronous (PMS) motors, as the fastest growing AC motor. It covers a deep and detailed presentation of major PMS motor modeling and control methods. The readers can find rich materials on the fundamentals of PMS motor control in addition to new motor control methods, which have mainly been developed in the last two decades, including recent advancements in the field in a systematic manner. These include extensive modeling of PMS motors and a full range of vector control and direct torque control schemes, in addition to predictive control, deadbeat control, and combined control methods. All major sensorless control and parameter estimation methods are also studied. The book covers about 10 machine models in various reference frames and 70 control and estimation schemes with sufficient analytical and implementation details including about 200 original figures. A great emphasis is placed on energy-s...

  18. 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 ...

  19. Structure and magnetic field of periodic permanent magnetic focusing system with open magnetic rings

    International Nuclear Information System (INIS)

    Peng Long; Li Lezhong; Yang Dingyu; Zhu Xinghua; Li Yuanxun

    2011-01-01

    The magnetic field along the central axis for an axially magnetized permanent magnetic ring was investigated by analytical and finite element methods. For open magnetic rings, both calculated and measured results show that the existence of the radial magnetic field creates a remarkable cosine distribution field along the central axis. A new structure of periodic permanent magnet focusing system with open magnetic rings is proposed. The structure provides a satisfactory magnetic field with a stable peak value of 120 mT for a traveling wave tube system. - Research highlights: → For open magnetic rings, both calculated and measured results show that the existence of the radial magnetic field creates a remarkable cosine distribution field along the central axis. → A new structure of periodic permanent magnet (PPM) focusing system with open magnetic rings is proposed. → The new PPM focusing system with open magnetic rings meets the requirements for TWT system.

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

    International Nuclear Information System (INIS)

    Deng, Z.; Zheng, J.; Li, J.; Ma, G.; Lu, Y.; Zhang, Y.; Wang, S.; Wang, J.

    2008-01-01

    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 magnet, it is

  1. 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

  2. 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.

  3. Possibilities of development photodynamic therapy under high temperature superconductor magnetic field

    International Nuclear Information System (INIS)

    Sen, Mihir

    1996-01-01

    After a long extensive research work neutron photon therapy for treatment of acquired immuno-deficiency syndrome (AIDS) was developed. High temperature superconductor magnet was developed and fitted in magnetic resonance imaging system to guide the patient. By this neutron-photon therapy AIDS effected cells are identified prominently. Patient is then injected with light sensitive drug molecules, which only AIDS cell retain. Light from photon (laser) then energizes the drug, which passes that energy to oxygen, which then leads a biochemical attack on the AIDS cells. If all goes well, the AIDS affected cells die. 10 refs., 1 fig

  4. Rotor for a line start permanent magnet machine

    Science.gov (United States)

    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.

  5. High temperature electrons exhausted from rf plasma sources along a magnetic nozzle

    Science.gov (United States)

    Takahashi, Kazunori; Akahoshi, Hikaru; Charles, Christine; Boswell, Rod W.; Ando, Akira

    2017-08-01

    Two dimensional profiles of electron temperature are measured inside and downstream of a radiofrequency plasma thruster source having a magnetic nozzle and being immersed in vacuum. The temperature is estimated from the slope of the fully swept I-V characteristics of a Langmuir probe acquired at each spatial position and with the assumption of a Maxwellian distribution. The results show that the peripheral high temperature electrons in the magnetic nozzle originate from the upstream antenna location and are transported along the "connecting" magnetic field lines. Two-dimensional measurements of electron energy probability functions are also carried out in a second simplified laboratory device consisting of the source contiguously connected to the diffusion chamber: again the high temperature electrons are detected along the magnetic field lines intersecting the wall at the antenna location, even when the antenna location is shifted along the main axis. These results demonstrate that the peripheral energetic electrons in the magnetic nozzle mirror those created in the source tube.

  6. 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.

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

    International Nuclear Information System (INIS)

    Vanderbemden, P; Hong, Z; Coombs, T A; Ausloos, M; Babu, N Hari; Cardwell, D A; Campbell, A M

    2007-01-01

    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

  8. 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

  9. Permanent magnets and its production by powder metallurgy

    Directory of Open Access Journals (Sweden)

    Enrique Herraiz Lalana

    2018-06-01

    Full Text Available In this work, the historical relationship between permanent magnets and powder metallurgy is reviewed. Powder metallurgy is a manufacturing technique based on the compaction of powders that are sintered to create a solid product. This technique was used in the production of permanent magnets for the first time in the 18th century and, nowadays, most permanent magnetic materials are manufacturing by this mean. Magnetic properties are highly dependent on the microstructure of the final product, the magnetic alignment of domains and presence of porosity, to mention a few, and powder metallurgy enables fine control of these factors.

  10. Macroscopic Magnetic Coupling Effect: The Physical Origination of a High-Temperature Superconducting Flux Pump

    Science.gov (United States)

    Wang, Wei; Coombs, Tim

    2018-04-01

    We have uncovered at the macroscopic scale a magnetic coupling phenomenon in a superconducting YBa2Cu3O7 -δ (YBCO) film, which physically explains the mechanism of the high-temperature superconducting flux pump. The coupling occurs between the applied magnetic poles and clusters of vortices induced in the YBCO film, with each cluster containing millions of vortices. The coupling energy is verified to originate from the inhomogeneous field of the magnetic poles, which reshapes the vortex distribution, aggregates millions of vortices into a single cluster, and accordingly moves with the poles. A contrast study is designed to verify that, to provide the effective coupling energy, the applied wavelength must be short while the field amplitude must be strong, i.e., local-field inhomogeneity is the crucial factor. This finding broadens our understanding of the collective vortex behavior in an applied magnetic field with strong local inhomogeneity. Moreover, this phenomenon largely increases the controlled vortex flow rate by several orders of magnitude compared with existing methods, providing motivation for and physical support to a new branch of wireless superconducting dc power sources, i.e., the high-temperature superconducting flux pump.

  11. Electronic and magnetic interactions in high temperature superconducting and high coercivity materials. Final performance report

    International Nuclear Information System (INIS)

    Cooper, B.R.

    1997-01-01

    The issue addressed in the research was how to understand what controls the competition between two types of phase transition (ordering) which may be present in a hybridizing correlated-electron system containing two transition-shell atomic species; and how the variation of behavior observed can be used to understand the mechanisms giving the observed ordered state. This is significant for understanding mechanisms of high-temperature superconductivity and other states of highly correlated electron systems. Thus the research pertains to magnetic effects as related to interactions giving high temperature superconductivity; where the working hypothesis is that the essential feature governing the magnetic and superconducting behavior of copper-oxide-type systems is a cooperative valence fluctuation mechanism involving the copper ions, as mediated through hybridization effects dominated by the oxygen p electrons. (Substitution of praseodymium at the rare earth sites in the 1·2·3 material provides an interesting illustration of this mechanism since experimentally such substitution strongly suppresses and destroys the superconductivity; and, at 100% Pr, gives Pr f-electron magnetic ordering at a temperature above 16K). The research was theoretical and computational and involved use of techniques aimed at correlated-electron systems that can be described within the confines of model hamiltonians such as the Anderson lattice hamiltonian. Specific techniques used included slave boson methodology used to treat modification of electronic structure and the Mori projection operator (memory function) method used to treat magnetic response (dynamic susceptibility)

  12. Prospects of High Temperature Superconductors for fusion magnets and power applications

    International Nuclear Information System (INIS)

    Fietz, Walter H.; Barth, Christian; Drotziger, Sandra; Goldacker, Wilfried; Heller, Reinhard; Schlachter, Sonja I.; Weiss, Klaus-Peter

    2013-01-01

    Highlights: • An overview of HTS application in fusion is given. • BSCCO application for current leads is discussed. • Several approaches to come to a high current HTS cable are shown. • Open issues and benefits of REBCO high current HTS cables are discussed. -- Abstract: During the last few years, progress in the field of second-generation High Temperature Superconductors (HTS) was breathtaking. Industry has taken up production of long length coated REBCO conductors with reduced angular dependency on external magnetic field and excellent critical current density jc. Consequently these REBCO tapes are used more and more in power application. For fusion magnets, high current conductors in the kA range are needed to limit the voltage during fast discharge. Several designs for high current cables using High Temperature Superconductors have been proposed. With the REBCO tape performance at hand, the prospects of fusion magnets based on such high current cables are promising. An operation at 4.5 K offers a comfortable temperature margin, more mechanical stability and the possibility to reach even higher fields compared to existing solutions with Nb 3 Sn which could be interesting with respect to DEMO. After a brief overview of HTS use in power application the paper will give an overview of possible use of HTS material for fusion application. Present high current HTS cable designs are reviewed and the potential using such concepts for future fusion magnets is discussed

  13. 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.

  14. Ce-didymium-Fe-B sintered permanent magnets

    International Nuclear Information System (INIS)

    Homma, M.; Okada, M.; Sugimoto, S.

    1985-01-01

    Present works report the development of the low cost R-Fe-B permanent magnets. The best magnetic properties obtained in this studies are Br=13.5 kG, iHc=10.2 kOe and (BH)max=40 MGOe with an Fe-33.5wt%(5Ce-Didymium)-1wt% B alloy. Topics considered in this paper include cerium alloys, boron alloys, fabrication, capitalized cost, iron alloys, permanent magnets, and magnetic properties

  15. 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.

  16. Modeling of ironless permanent magnet planar motor structures

    NARCIS (Netherlands)

    Boeij, de J.; Lomonova, E.A.; Vandenput, A.J.A.

    2006-01-01

    This paper describes an analytical model that includes end effects for ironless synchronous permanent-magnet planar actuators. Because of its flexibility, the model can be used to predict the performance of various permanent-magnet array and coil array topologies and commutation schemes. Moreover,

  17. Method and apparatus for assembling a permanent magnet pole assembly

    Science.gov (United States)

    Carl, Jr., Ralph James; Bagepalli, Bharat Sampathkumaran [Niskayuna, NY; Jansen, Patrick Lee [Scotia, NY; Dawson, Richard Nils [Voorheesville, NY; Qu, Ronghai [Clifton Park, NY; Avanesov, Mikhail Avramovich [Moscow, RU

    2009-08-11

    A pole assembly for a rotor, the pole assembly includes a permanent magnet pole including at least one permanent magnet block, a plurality of laminations including a pole cap mechanically coupled to the pole, and a plurality of laminations including a base plate mechanically coupled to the pole.

  18. Sensorless V/f Control of Permanent Magnet Synchronous Motors

    OpenAIRE

    Montesinos-Miracle, Daniel; Perera, P. D. Chandana; Galceran-Arellano, Samuel; Blaabjerg, Frede

    2010-01-01

    V/f control strategy for permanent magnet synchronous motors can be useful for HVAC applications, where not high performance is required. Permanent magnet synchronous motors have efficiency advantages over the induction motor. But open loop V/f control is not stable in the whole frequency range. As demonstrated, the V/f control strategy becomes

  19. Magnetic levitation/suspension system by high-temperature superconducting materials

    International Nuclear Information System (INIS)

    Chen, I.; Hsu, J.; Jamn, G.; Lin, C.E.; Wu, M.K.

    1997-01-01

    Recently, with the advance of materials processing techniques, such as top-seeding and melt-texturing (TSMT) method, very large single-grained Y-Ba-Cu-O (YBCO) samples up to several centimeters in diameter can be produced. Each sample is capable of levitating over kilograms of weight. A HTS magnetic levitation (MagLev) transportation prototype has been constructed at National Cheng-Kung University (NCKU) to validate the concept of HTS-MagLev system based on Meissner effect. This HTS-MagLev is an inherent stable levitation system, unlike traditional MagLev system that requires sensors and feedback circuits to dynamically adjust its unstable levitation position. In this report, the results of various magnetic levitation parameters, such as different permanent magnet configurations, relative levitation stability, levitation force, etc., as well as magnetic field intensity and distribution will be discussed. copyright 1997 American Institute of Physics

  20. No-insulation multi-width winding technique for high temperature superconducting magnet.

    Science.gov (United States)

    Hahn, Seungyong; Kim, Youngjae; Keun Park, Dong; Kim, Kwangmin; Voccio, John P; Bascuñán, Juan; Iwasa, Yukikazu

    2013-10-21

    We present a No-Insulation ( NI ) Multi-Width ( MW ) winding technique for an HTS (high temperature superconductor) magnet consisting of double-pancake (DP) coils. The NI enables an HTS magnet self-protecting and the MW minimizes the detrimental anisotropy in current-carrying capacity of HTS tape by assigning tapes of multiple widths to DP coils within a stack, widest tape to the top and bottom sections and the narrowest in the midplane section. This paper presents fabrication and test results of an NI-MW HTS magnet and demonstrates the unique features of the NI-MW technique: self-protecting and enhanced field performance, unattainable with the conventional technique.

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

    International Nuclear Information System (INIS)

    Pretzell, Alf

    2012-01-01

    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.

  2. 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.

  3. Open H-shaped permanent magnet structure for NMR imaging

    International Nuclear Information System (INIS)

    Nguyen, V.; Delamare, J.; Yonnet, J.P.

    1996-01-01

    Since NMR imaging at low field is now technically possible, permanent magnets can replace resistive coils or superconducting magnets. This paper reviews most of NMR structures that provide an uniform field using only permanent magnets. We propose a new open H-shaped structure that is simple to manufacture. This structure has been calculated thanks to an optimization program and a calculation method we presente here. It enables to determine with a good accuracy the field created by passive systems composed by permanent magnets and ferromagnetic materials. (author)

  4. Hydrogen stability of SmCo5 permanent magnet

    International Nuclear Information System (INIS)

    Lukin, A.; Rabinovich, Y.; Bala, H.

    2001-01-01

    The present work has been performed with purpose to determine the level of hydrogen stability of sintered SmCo 5 permanent magnets by means of accelerated tests, to study the effect of hydrogen on the magnetic and mechanical properties of the permanent magnets and to establish the criteria of hydrogenation level and the activation energy of this process. In addition, the effect of hydrogen on the properties of sintered SmCo 5 permanent magnets in specific conditions of exploitation and storage durability of instruments was studied

  5. 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...... remains unsolved. We show that the problem of optimal segmentation of a two-dimensional permanent-magnet assembly with respect to a linear objective functional can be reduced to the problem of piecewise linear approximation of a plane curve by perimeter maximization. Once the problem has been cast...

  6. Installation for microwave investigations of high-temperature superconductivity in magnetic field

    CERN Document Server

    Akhvlediani, I G; Mamniashvili, G I; Chigvinadze, D G

    2002-01-01

    Paper describes advanced EPR-spectrometer RE 1306 designed to investigate into structure of magnetic flux in high-temperature superconductors (HTSC). To measure in low fields one uses power source generating current within 0-600 mA limits and 10-500 Gauss field. To ensure temperature studies of HTSC within up to approx 15 K range one used helium and nitrogen cold steam blowing through resonator of EPR-spectrometer. To stabilize specimen temperature prior to cold steams enter double tube one fixed one more heater

  7. Capital and operating cost estimates for high temperature superconducting magnetic energy storage

    International Nuclear Information System (INIS)

    Schoenung, S.M.; Meier, W.R.; Fagaly, R.L.; Heiberger, M.; Stephens, R.B.; Leuer, J.A.; Guzman, R.A.

    1992-01-01

    Capital and operating costs have been estimated for mid-scale (2 to 200 Mwh) superconducting magnetic energy storage (SMES) designed to use high temperature superconductors (HTS). Capital costs are dominated by the cost of superconducting materials. Operating costs, primarily for regeneration, are significantly reduced for HTS-SMES in comparison to low temperature, conventional systems. This cost component is small compared to other O and M and capital components, when levelized annual costs are projected. In this paper, the developments required for HTS-SMES feasibility are discussed

  8. IEFIT - An Interactive Approach to High Temperature Fusion Plasma Magnetic Equilibrium Fitting

    International Nuclear Information System (INIS)

    Peng, Q.; Schachter, J.; Schissel, D.P.; Lao, L.L.

    1999-01-01

    An interactive IDL based wrapper, IEFIT, has been created for the magnetic equilibrium reconstruction code EFIT written in FORTRAN. It allows high temperature fusion physicists to rapidly optimize a plasma equilibrium reconstruction by eliminating the unnecessarily repeated initialization in the conventional approach along with the immediate display of the fitting results of each input variation. It uses a new IDL based graphics package, GaPlotObj, developed in cooperation with Fanning Software Consulting, that provides a unified interface with great flexibility in presenting and analyzing scientific data. The overall interactivity reduces the process to minutes from the usual hours

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

    International Nuclear Information System (INIS)

    Halbach, K.

    1984-09-01

    After an explanation of the general circumstances in which the use of permanent magnets in accelerators is desirable, a number of specific magnets will be discussed. That discussion includes magnets needed for the operation of accelerators as well as magnets that are employed for the utilization of charged particle beams, such as the production of synchrotron radiation. 15 references, 8 figures

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    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...

  11. Dovetail Rotor Construction For Permanent-Magnet Motors

    Science.gov (United States)

    Kintz, Lawrence J., Jr.; Puskas, William J.

    1988-01-01

    New way of mounting magnets in permanent-magnet, electronically commutated, brushless dc motors. Magnets wedge shaped, tapering toward center of rotor. Oppositely tapered pole pieces, electron-beam welded to rotor hub, retain magnets against centrifugal force generated by spinning rotor. To avoid excessively long electron-beam welds, pole pieces assembled in segments rather than single long bars.

  12. 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.

  13. High Temperature Superconducting Magnets with Active Control for Attraction Levitation Transport Applications

    Science.gov (United States)

    Jones, Harry; Jenkins, Richard G.; Goodall, Roger M.; Macleod, Colin; ElAbbar, Abdallah A.; Campbell, Archie M.

    1996-01-01

    A research program, involving 3 British universities, directed at quantifying the controllability of High Temperature Superconducting (HTS) magnets for use in attraction levitation transport systems will be described. The work includes measurement of loss mechanisms for iron cored HTS magnets which need to produce a flux density of approx. 1 tesla in the airgap between the magnet poles and a ferromagnetic rail. This flux density needs to be maintained and this is done by introducing small variations of the magnet current using a feedback loop, at frequencies up to 10 Hz to compensate for load changes, track variation etc. The test magnet assemblies constructed so far will be described and the studies and modelling of designs for a practical levitation demonstrator (using commercially obtained HTS tape) will be discussed with particular emphasis on how the field distribution and its components, e.g., the component vector normal to the broad face of the tape, can radically affect design philosophy compared to the classical electrical engineering approach. Although specifically aimed at levitation transport the controllability data obtained have implications for a much wider range of applications.

  14. Motional Stark Effect measurements of the local magnetic field in high temperature fusion plasmas

    Science.gov (United States)

    Wolf, R. C.; Bock, A.; Ford, O. P.; Reimer, R.; Burckhart, A.; Dinklage, A.; Hobirk, J.; Howard, J.; Reich, M.; Stober, J.

    2015-10-01

    The utilization of the Motional Stark Effect (MSE) experienced by the neutral hydrogen or deuterium injected into magnetically confined high temperature plasmas is a well established technique to infer the internal magnetic field distribution of fusion experiments. In their rest frame, the neutral atoms experience a Lorentz electric field, EL = v × B, which results in a characteristic line splitting and polarized line emission. The different properties of the Stark multiplet allow inferring, both the magnetic field strength and the orientation of the magnetic field vector. Besides recording the full MSE spectrum, several types of polarimeters have been developed to measure the polarization direction of the Stark line emission. To test physics models of the magnetic field distribution and dynamics, the accuracy requirements are quite demanding. In view of these requirements, the capabilities and issues of the different techniques are discussed, including the influence of the Zeeman Effect and the sensitivity to radial electric fields. A newly developed Imaging MSE system, which has been tested on the ASDEX Upgrade tokamak, is presented. The sensitivity allows to resolve sawtooth oscillations. A shorter version of this contribution is due to be published in PoS at: 1st EPS conference on Plasma Diagnostics

  15. Micro magnetic modeling of magnetization reversal in permanent magnets

    International Nuclear Information System (INIS)

    Toussaint, J.C.; Kevorkian, B.; Givord, D.; Rossignol, M.F.

    1996-01-01

    Micro magnetic numerical 3 D calculation is presented in this paper to investigate the effect of a soft magnetic heterogeneity on the magnetization reversal of a single hard magnetic grain. Both equilibrium and transient magnetization configurations are obtained by solving the dynamic Landau-Lifshitz-Gilbert (L.L.G.) equation. A modified forward difference method is used to integrate the time dependent L.L.G. equation without conflicting with the constraint of constant magnetic moment. A continuum view of the material medium is adopted and the spatial finite difference method is used to describe the system as a set of cubic elements. In each element the magnetization is interpolated with quadratic polynomial functions and constrained to follow the Brown condition at the surface. A multigrid approach is developed to calculate the magnetic potential and the resulting stray field associated with a given microstructure. The calculated properties are compared to actual properties of Nd Fe B sintered magnets. Assuming a soft nucleus of 160 angstrom diameter and 80 angstrom depth, the calculated coercive field is about 1.45 T, close to experimental values and the calculated angular dependence of H c resembles experimental behaviours. (author)

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

    International Nuclear Information System (INIS)

    Lund, S.M.; Halbach, K.

    1995-01-01

    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

  17. Method and apparatus for assembling permanent magnet rotors

    Science.gov (United States)

    Hsu, J.S.; Adams, D.J.

    1999-06-22

    A permanent magnet assembly for assembly in large permanent magnet motors and generators includes a two-piece carrier that can be slid into a slot in the rotor and then secured in place using a set screw. The invention also provides an auxiliary carrier device with guide rails that line up with the teeth of the rotor, so that a permanent magnet assembly can be pushed first into a slot, and then down the slot to its proper location. An auxiliary tool is provided to move the permanent magnet assembly into position in the slot before it is secured in place. Methods of assembling and disassembling the magnet assemblies in the rotor are also disclosed. 2 figs.

  18. Study of the polymer permanent magnets properties - rare earths

    International Nuclear Information System (INIS)

    Takiishi, H.; Benini, H.R.; Lima, L.F.C.P.; Faria, R.N.

    1996-01-01

    An alternative method for permanent magnet production without the sintering step is polymer bonded magnets. In this work magnets were prepared from magnetic Sm Co 5 or Nd 15 Fe 77 B 8 alloys bonded with 10% wt of resin. For the Nd 15 Fe 77 B 8 alloy the hydrogenation - decomposition - desorption - recombination (HDDR) process have been employed in the preparation of the magnets. Results from the magnetic properties showed that no milling is necessary for the production of polymer bonded Nd-Fe-B magnets. The magnets showed good magnetic properties. (author)

  19. Design and control of a superconducting permanent magnet synchronous motor

    International Nuclear Information System (INIS)

    Jiang, Y; Pei, R; Hong, Z; Song, J; Fang, F; Coombs, T A

    2007-01-01

    This paper gives a detailed description of the design of a superconducting permanent magnet synchronous motor. The parameters of the motor have been identified, and the torque equation has been stated. A direct torque control algorithm is introduced and applied to a traditional permanent magnet synchronous motor and the superconducting permanent magnet synchronous motor described in this paper. The motor performance shows that the direct torque control algorithm provides excellent control to the superconducting motor, and guarantees that the magnitude of the operational armature currents is smaller than the value of the critical current of the superconducting tape used for stator winding

  20. Design and control of a superconducting permanent magnet synchronous motor

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Y [Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ (United Kingdom); Pei, R [Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ (United Kingdom); Hong, Z [Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ (United Kingdom); Song, J [Huazhong University of Science of Technology, Wuhan 430074 (China); Fang, F [Huazhong University of Science of Technology, Wuhan 430074 (China); Coombs, T A [Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ (United Kingdom)

    2007-07-15

    This paper gives a detailed description of the design of a superconducting permanent magnet synchronous motor. The parameters of the motor have been identified, and the torque equation has been stated. A direct torque control algorithm is introduced and applied to a traditional permanent magnet synchronous motor and the superconducting permanent magnet synchronous motor described in this paper. The motor performance shows that the direct torque control algorithm provides excellent control to the superconducting motor, and guarantees that the magnitude of the operational armature currents is smaller than the value of the critical current of the superconducting tape used for stator winding.

  1. Samarium-cobalt type rare earth permanent magnets

    International Nuclear Information System (INIS)

    Kamat, S.V.

    2014-01-01

    Permanent magnets are one of the oldest and largest applications of magnetic materials and form an integral part of our modern industrial society. They belong to a special class of functional materials and are characterized for remanence (flux output from the magnet), coercivity (resistance to demagnetization) and energy product (material energy density) from the second quadrant of the magnetic hysteresis loop. The reliability, stability, size, weight, cost and performance of many electro-technical devices depend mainly on the properties of permanent magnets used in them. There are three important families of permanent magnets viz., Ferrites, Alnicos and Rare Earth Permanent Magnets (REPMs) with energy product values ranging from 3 to 50 MGOe and among the front ranking high performance REPMs, SmCo 5 , Sm 2 Co 17 type and NdFeB alloys are technologically the most important materials. They are used in a wide range of applications ranging from consumer products to very specialized areas of tele-communications, microelectronics, defence, space, avionics etc. While NdFeB has the highest energy product, Sm-Co based magnets are preferred for most critical applications where temperature stability of magnetic properties is essential because of their significantly higher Curie temperatures. In this presentation some of the key challenges associated with these Sm-Co based rare earth permanent magnets will be highlighted. (author)

  2. 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.

  3. A new type of permanent magnet ondulator and wiggler

    International Nuclear Information System (INIS)

    Jianming, X.; Maosan, L.; Qing, X.

    1987-01-01

    A new type of permanent magnet ondulator and wiggler is discussed. In this new design the magnet is composed of permanent magnet segments with modulated thickness. The magnetization directions of the segments are all perpendicular to the symmetrical plane of the magnet gap. By modulating the thicknesses of the segments, the field distribution is a pure sinusoidal curve in the ideal 2-dimensional case. The spatial expressions of the magnet field in the ideal case and in the real case are given. The methods for reducing the undesirable harmonics in the magnet field in the real case are discussed. Because of the arrangement of the magnetization directions of the magnet segments, soft iron shield can be used to strenghten the magnet field. In some cases, the stregnthening factor is more than two. The strenghtening effect of the soft iron shield is analysed also

  4. Stress analysis in high-temperature superconductors under pulsed field magnetization

    Science.gov (United States)

    Wu, Haowei; Yong, Huadong; Zhou, Youhe

    2018-04-01

    Bulk high-temperature superconductors (HTSs) have a high critical current density and can trap a large magnetic field. When bulk superconductors are magnetized by the pulsed field magnetization (PFM) technique, they are also subjected to a large electromagnetic stress, and the resulting thermal stress may cause cracking of the superconductor due to the brittle nature of the sample. In this paper, based on the H-formulation and the law of heat transfer, we can obtain the distributions of electromagnetic field and temperature, which are in qualitative agreement with experiment. After that, based on the dynamic equilibrium equations, the mechanical response of the bulk superconductor is determined. During the PFM process, the change in temperature has a dramatic effect on the radial and hoop stresses, and the maximum radial and hoop stress are 24.2 {{MPa}} and 22.6 {{MPa}}, respectively. The mechanical responses of a superconductor for different cases are also studied, such as the peak value of the applied field and the size of bulk superconductors. Finally, the stresses are also presented for different magnetization methods.

  5. 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.

  6. Superstrong Adjustable Permanent Magnet for a Linear Collider Final Focus

    CERN Document Server

    Iwashita, Y

    2004-01-01

    Super-strong permanent magnets are being considered as one of the candidates for the final focus quadrupole magnets in a linear collider. A short prototype with temperature compensation included and variable strength capability has been designed and fabricated. Fabrication details and some magnetic measurement results will be presented.

  7. 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…

  8. Design, analysis and fabrication of a linear permanent magnet ...

    Indian Academy of Sciences (India)

    MONOJIT SEAL

    Linear permanent magnet synchronous machine; LPMSM—fabrication; design optimisation; finite-element ... induction motor (LIM) prototype was patented in 1890 [1]. Since then, linear ..... Also, for manual winding, more slot area is allotted to ...

  9. Self-suspended permanent magnetic FePt ferrofluids

    KAUST Repository

    Dallas, Panagiotis; Kelarakis, Antonios; Sahore, Ritu; DiSalvo, Francis J.; Livi, Sebastien; Giannelis, Emmanuel P.

    2013-01-01

    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

  10. Micromagnetics of rare-earth efficient permanent magnets

    Science.gov (United States)

    Fischbacher, Johann; Kovacs, Alexander; Gusenbauer, Markus; Oezelt, Harald; Exl, Lukas; Bance, Simon; Schrefl, Thomas

    2018-05-01

    The development of permanent magnets containing less or no rare-earth elements is linked to profound knowledge of the coercivity mechanism. Prerequisites for a promising permanent magnet material are a high spontaneous magnetization and a sufficiently high magnetic anisotropy. In addition to the intrinsic magnetic properties the microstructure of the magnet plays a significant role in establishing coercivity. The influence of the microstructure on coercivity, remanence, and energy density product can be understood by using micromagnetic simulations. With advances in computer hardware and numerical methods, hysteresis curves of magnets can be computed quickly so that the simulations can readily provide guidance for the development of permanent magnets. The potential of rare-earth reduced and rare-earth free permanent magnets is investigated using micromagnetic simulations. The results show excellent hard magnetic properties can be achieved in grain boundary engineered NdFeB, rare-earth magnets with a ThMn12 structure, Co-based nano-wires, and L10-FeNi provided that the magnet’s microstructure is optimized.

  11. High temperature superconductor micro-superconducting-quantum-interference-device magnetometer for magnetization measurement of a microscale magnet.

    Science.gov (United States)

    Takeda, Keiji; Mori, Hatsumi; Yamaguchi, Akira; Ishimoto, Hidehiko; Nakamura, Takayoshi; Kuriki, Shinya; Hozumi, Toshiya; Ohkoshi, Shin-ichi

    2008-03-01

    We have developed a high temperature superconductor (HTS) micrometer-sized dc superconducting quantum interference device (SQUID) magnetometer for high field and high temperature operation. It was fabricated from YBa2Cu3O7-delta of 92 nm in thickness with photolithography techniques to have a hole of 4x9 microm2 and 2 microm wide grain boundary Josephson junctions. Combined with a three dimensional magnetic field coil system, the modulation patterns of critical current Ic were observed for three different field directions. They were successfully used to measure the magnetic properties of a molecular ferrimagnetic microcrystal (23x17x13 microm3), [Mn2(H2O)2(CH3COO)][W(CN)8]2H2O. The magnetization curve was obtained in magnetic field up to 0.12 T between 30 and 70 K. This is the first to measure the anisotropy of hysteresis curve in the field above 0.1 T with an accuracy of 10(-12) J T(-1) (10(-9) emu) with a HTS micro-SQUID magnetometer.

  12. Use of permanent magnets in accelerator technology: Present and future

    International Nuclear Information System (INIS)

    Halbach, K.

    1987-01-01

    Permanent magnet systems have some generic properties that, under some circumstances, make them not only mildy preferable over electromagnets, but make it possible to do things that can not be done with any other technology. After a general discussion of these generic advantages, some specific permanent magnet systems will be described. Special emphasis will be placed on systems that have now, or are likely to have in the future, a significant impact on how some materials research is conducted

  13. Permanent magnet material and process for producing the same

    International Nuclear Information System (INIS)

    Yoneyama, T.; Hori, T.; Ohima, T.

    1978-01-01

    This invention relates to an improvement of a permanent magnet material consisting, apart from impurities, of intermetallic compounds of the general formula of R 2 Co 17 , wherein the R component is at least one rare earth metal excluding radioactive elements and the Co component is cobalt. A suitable process to produce the permanent magnet material according to the invention is described. (U.K.)

  14. Implementation of Permanent Magnet Motors in Electric Vehicles

    OpenAIRE

    Elvestad, Eirik

    2008-01-01

    This thesis has studied permanent magnet motors in electric vehicles (EVs) under the assumption that they are tractable due to a low weight and high compactness. The implementation has been investigated through a case study, which resulted in an EV simulation model. The model contains a maximal torque per ampere and a closed-loop field weakening controller. Abstract Faults are a special concern in permanent magnet motors. Fault sources and faulted behavior are addressed separately. The EV mo...

  15. A tubular flux-switching permanent magnet machine

    Science.gov (United States)

    Wang, J.; Wang, W.; Clark, R.; Atallah, K.; Howe, D.

    2008-04-01

    The paper describes a novel tubular, three-phase permanent magnet brushless machine, which combines salient features from both switched reluctance and permanent magnet machine technologies. It has no end windings and zero net radial force and offers a high power density and peak force capability, as well as the potential for low manufacturing cost. It is, therefore, eminently suitable for a variety of applications, ranging from free-piston energy converters to active vehicle suspensions.

  16. 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.

  17. Exterior rotor permanent magnet generator in variable speed applications

    OpenAIRE

    Sattar, Rauf

    2016-01-01

    This thesis explores approaches for converting rotational mechanical power from diesel engines into electrical power of fixed frequency and voltage. Advances in high energy permanent magnets and power electronics are enabling technologies that provide opportunities for electrical machines with increased efficiency and compact size for variable speed power generation. The overall objective was to design a permanent magnet machine with concentrated winding that could be used in variable spe...

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

    International Nuclear Information System (INIS)

    Zheng, J.; Liao, X.L.; Jing, H.L.; Deng, Z.G.; Yen, F.; Wang, S.Y.; Wang, J.S.

    2013-01-01

    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

  19. 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.

  20. A high temperature superconductor tape RF receiver coil for a low field magnetic resonance imaging system

    International Nuclear Information System (INIS)

    Cheng, M C; Yan, B P; Lee, K H; Ma, Q Y; Yang, E S

    2005-01-01

    High temperature superconductor (HTS) thin films have been applied in making a low loss RF receiver coil for improving magnetic resonance imaging image quality. However, the application of these coils is severely limited by their limited field of view (FOV). Stringent fabrication environment requirements and high cost are further limitations. In this paper, we propose a simpler method for designing and fabricating HTS coils. Using industrial silver alloy sheathed Bi (2-x) Pb x Sr 2 Ca 2 Cu 3 O 10 (Bi-2223) HTS tapes, a five-inch single-turn HTS solenoid coil has been developed, and human wrist images have been acquired with this coil. The HTS tape coil has demonstrated an enhanced FOV over a six-inch YBCO thin film surface coil at 77 K with comparable signal-to-noise ratio

  1. Investigation of magnetic reconnection during a sawtooth crash in a high temperature tokamak

    International Nuclear Information System (INIS)

    Yamada, M.; Pomphrey, N.; Budney, R.; Macickam, J.; Nagayama, Y.

    1994-09-01

    This paper reports on a recent laboratory investigation on magnetic reconnection in high temperature tokamak plasmas. The motional stark effect(MSE) diagnostic is employed to measure the pitch angle of magnetic field lines, and hence the q profile. An analytical expression that relates pitch angle to q profile has been developed for a toroidal plasma with circular cross section. During the crash phase of sawtooth oscillations in the plasma discharges, the ECE (electron cyclotron emission) diagnostic measures a fast flattening of the 2-D electron temperature profile in a poloidal plane, an observation consistent with the Kadomtsev reconnection theory. On the other hand motional the MSE measurements indicate that central q values do not relax to unity after the crash, but increase only by 5-10%, typically from 0.7 to 0.75. The latter result is in contradiction with the models of Kadomtsev and/or Wesson. The present study addresses this puzzle by a simultaneous analysis of electron temperature and q profile evolutions. Based on a heuristic model for the magnetic reconnection during the sawtooth crash, the small change of q, i.e. partial reconnection, is attributed to the precipitous drop of pressure gradients which drive the instability and the reconnection process as well as flux conserving plasma dynamics

  2. The magnetic properties of mill scale-derived permanent magnet

    International Nuclear Information System (INIS)

    Woon, H.S.; Hashim, M.M.; Yahya, N.; Zakaria, A.; Lim, K.P.

    2005-01-01

    In the permanent magnet SrO-FeO-Fe 2 O 3 system, there exist several magnetically ordered compounds with a stable phase at room temperature. The most important are the M(SrFe 12 O 19 ), X(SrFe 15 O 23 ) and W(SrFe 18 O 27 ) phases with hexagonal close packed structure. In this project, M(SrFe 12 O 19 ) was prepared using mill scale, a steel-maker byproduct, as raw material. The Malaysia steel industry generates approximately 30,000 metric tons of waste products such as mill scale every year. Transportation and disposal of the byproducts are costly and the environmental regulations are becoming stricter. Hence, local steel mills are to find new ways to recycle the waste as a feedstock for the steel-making process or as a saleable product. The M(SrFe 12 O 19 ) was synthesized using the conventional ceramic process. The formation of the SrFe 12 O 19 was confirmed by X-ray diffraction. The magnetic properties such as the energy product (BH)max, coercive force (iHc) and remanence (Br) were also reported in this paper. (Author)

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

    International Nuclear Information System (INIS)

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

    2010-01-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    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.

  5. Design and simulation of permanent magnet synchronous motor control system

    Science.gov (United States)

    Li, Li; Liu, Yongqiu

    2018-06-01

    In recent years, with the development of power electronics, microelectronics, new motor control theory and rare earth permanent magnet materials, permanent magnet synchronous motors have been rapidly applied. Permanent magnet synchronous motors have the advantages of small size, low loss and high efficiency. Today, energy conservation and environmental protection are increasingly valued. It is very necessary to study them. Permanent magnet synchronous motor control system has a wide range of application prospects in the fields of electric vehicles, ships and other transportation. Using the simulation function of MATLAB/SIMULINK, a modular design structure was used to simulate the whole system model of speed loop adjustment, current PI modulation, SVPWM (Space Vector Pulse Width Module) wave generation and double closed loop. The results show that this control method has good robustness, and this method can improve the design efficiency and shorten the system design time. In this article, the analysis of the control principle of modern permanent magnet synchronous motor and the various processes of MATLAB simulation application will be analyzed in detail. The basic theory, basic method and application technology of the permanent magnet synchronous motor control system are systematically introduced.

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

    International Nuclear Information System (INIS)

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

    2011-01-01

    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.

  7. 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.

  8. 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.

  9. High energy permanent magnets - Solutions to high performance devices

    International Nuclear Information System (INIS)

    Ma, B.M.; Willman, C.J.

    1986-01-01

    Neodymium iron boron magnets are a special class of magnets providing the highest level of performance with the least amount of material. Crucible Research Center produced the highest energy product magnet of 45 MGOe - a world record. Commercialization of this development has already taken place. Crucible Magnetics Division, located in Elizabethtown, Kentucky, is currently manufacturing and marketing six different grades of NdFeB magnets. Permanent magnets find application in motors, speakers, electron beam focusing devices for military and Star Wars. The new NdFeB magnets are of considerable interest for a wide range of applications

  10. 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.

  11. Permanent-magnet-less machine having an enclosed air gap

    Science.gov (United States)

    Hsu, John S [Oak Ridge, TN

    2012-02-07

    A permanent magnet-less, brushless synchronous system includes a stator that generates a magnetic rotating field when sourced by an alternating current. An uncluttered rotor disposed within the magnetic rotating field is spaced apart from the stator to form an air gap relative to an axis of rotation. A stationary excitation core spaced apart from the uncluttered rotor by an axial air gap and a radial air gap substantially encloses the stationary excitation core. Some permanent magnet-less, brushless synchronous systems include stator core gaps to reduce axial flux flow. Some permanent magnet-less, brushless synchronous systems include an uncluttered rotor coupled to outer laminations. The quadrature-axis inductance may be increased in some synchronous systems. Some synchronous systems convert energy such as mechanical energy into electrical energy (e.g., a generator); other synchronous systems may convert any form of energy into mechanical energy (e.g., a motor).

  12. Nanostructured silicon ferromagnet collected by a permanent neodymium magnet.

    Science.gov (United States)

    Okuno, Takahisa; Thürmer, Stephan; Kanoh, Hirofumi

    2017-11-30

    Nanostructured silicon (N-Si) was prepared by anodic electroetching of p-type silicon wafers. The obtained magnetic particles were separated by a permanent neodymium magnet as a magnetic nanostructured silicon (mN-Si). The N-Si and mN-Si exhibited different magnetic properties: the N-Si exhibited ferromagnetic-like behaviour, whereas the mN-Si exhibited superparamagnetic-like behaviour.

  13. Magnetic levitation using high temperature superconducting pancake coils as composite bulk cylinders

    International Nuclear Information System (INIS)

    Patel, A; Hopkins, S C; Baskys, A; Glowacki, B A; Kalitka, V; Molodyk, A

    2015-01-01

    Stacks of superconducting tape can be used as composite bulk superconductors for both trapped field magnets and for magnetic levitation. Little previous work has been done on quantifying the levitation force behavior between stacks of tape and permanent magnets. This paper reports the axial levitation force properties of superconducting tape wound into pancake coils to act as a composite bulk cylinder, showing that similar stable forces to those expected from a uniform bulk cylinder are possible. Force creep was also measured and simulated for the system. The geometry tested is a possible candidate for a rotary superconducting bearing. Detailed finite element modeling in COMSOL Multiphysics was also performed including a full critical state model for induced currents, with temperature and field dependent properties and 3D levitation force models. This work represents one of the most complete levitation force modeling frameworks yet reported using the H-formulation and helps explain why the coil-like stacks of tape are able to sustain levitation forces. The flexibility of geometry and consistency of superconducting properties offered by stacks of tapes, make them attractive for superconducting levitation applications. (paper)

  14. Theoretical validation for changing magnetic fields of systems of permanent magnets of drum separators

    Science.gov (United States)

    Lozovaya, S. Y.; Lozovoy, N. M.; Okunev, A. N.

    2018-03-01

    This article is devoted to the theoretical validation of the change in magnetic fields created by the permanent magnet systems of the drum separators. In the article, using the example of a magnetic separator for enrichment of highly magnetic ores, the method of analytical calculation of the magnetic fields of systems of permanent magnets based on the Biot-Savart-Laplace law, the equivalent solenoid method, and the superposition principle of fields is considered.

  15. Quasiparticles of strongly correlated Fermi liquids at high temperatures and in high magnetic fields

    International Nuclear Information System (INIS)

    Shaginyan, V. R.

    2011-01-01

    Strongly correlated Fermi systems are among the most intriguing, best experimentally studied and fundamental systems in physics. There is, however, lack of theoretical understanding in this field of physics. The ideas based on the concepts like Kondo lattice and involving quantum and thermal fluctuations at a quantum critical point have been used to explain the unusual physics. Alas, being suggested to describe one property, these approaches fail to explain the others. This means a real crisis in theory suggesting that there is a hidden fundamental law of nature. It turns out that the hidden fundamental law is well forgotten old one directly related to the Landau-Migdal quasiparticles, while the basic properties and the scaling behavior of the strongly correlated systems can be described within the framework of the fermion condensation quantum phase transition (FCQPT). The phase transition comprises the extended quasiparticle paradigm that allows us to explain the non-Fermi liquid (NFL) behavior observed in these systems. In contrast to the Landau paradigm stating that the quasiparticle effective mass is a constant, the effective mass of new quasiparticles strongly depends on temperature, magnetic field, pressure, and other parameters. Our observations are in good agreement with experimental facts and show that FCQPT is responsible for the observed NFL behavior and quasiparticles survive both high temperatures and high magnetic fields.

  16. Prediction of the new efficient permanent magnet SmCoNiFe3

    Science.gov (United States)

    Söderlind, P.; Landa, A.; Locht, I. L. M.; Åberg, D.; Kvashnin, Y.; Pereiro, M.; Däne, M.; Turchi, P. E. A.; Antropov, V. P.; Eriksson, O.

    2017-09-01

    We propose a new efficient permanent magnet, SmCoNiFe3, which is a development of the well-known SmCo5 prototype. More modern neodymium magnets of the Nd-Fe-B type have an advantage over SmCo5 because of their greater maximum energy products due to their iron-rich stoichiometry. Our new magnet, however, removes most of this disadvantage of SmCo5 while preserving its superior high-temperature efficiency over the neodymium magnets. We show by means of first-principles electronic-structure calculations that SmCoNiFe3 has very favorable magnetic properties and could therefore potentially replace SmCo5 or Nd-Fe-B types in various applications.

  17. Large permanent magnet quadrupoles for an electron storage ring

    International Nuclear Information System (INIS)

    Herb, S.W.

    1987-01-01

    We have built large high quality permanent magnet quadrupoles for use as interaction region quadrupoles in the Cornell Electron Storage Ring where they must operate in the 10 kG axial field of the CLEO experimental detector. We describe the construction and the magnetic measurement and tuning procedures used to achieve the required field quality and stability. (orig.)

  18. Magnetostatic interactions and forces between cylindrical permanent magnets

    Czech Academy of Sciences Publication Activity Database

    Vokoun, David; Beleggia, M.; Heller, Luděk; Šittner, Petr

    2009-01-01

    Roč. 321, č. 22 (2009), s. 3758-3763 ISSN 0304-8853 EU Projects: European Commission(XE) 46559 - CERINKA Institutional research plan: CEZ:AV0Z10100520 Keywords : cylinder * force measurement * magnetostatic * permanent magnet Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.204, year: 2009

  19. Mechanical design and fabrication of pure-permanent magnet undulator

    International Nuclear Information System (INIS)

    Chouksey, Sanjay; Vinit Kumar; Abhay Kumar; Krishnagopal, Srinivas

    2003-01-01

    A 50 mm period, 2.5 m long (50 periods), pure permanent magnet, variable gap undulator using NdFeB magnets is being built in two sections, each 1.25 m long. We present details of the mechanical design, fabrication experience, assembly and inspection of the undulator. (author)

  20. Periodic permanent magnet focusing system with high peak field

    International Nuclear Information System (INIS)

    Zhang Hong; Liu Weiwei; Bai Shuxin; Chen Ke

    2008-01-01

    In this study, hybrid periodic permanent magnet (PPM) system is studied, which has high axial magnetic field and low magnetic leakage. By simulation computation, some laws of magnetic field distribution vs. structure dimensions were obtained. A hybrid PPM is designed and constructed whose peak field reaches 0.6 T. The factors inducing discrepancies between computational results and practical measurements are analyzed. The magnetic field distribution is very sensitive to the variations of constructional parameters. Construction accuracy greatly influences the magnetic field distribution. Research results obtained here are potentially valuable for future work

  1. Use of permanent magnets in accelerator technology: Present and future

    International Nuclear Information System (INIS)

    Halbach, K.

    1987-05-01

    This report is a collection of viewgraphs discussing accelerator magnets. Permanent magnet systems have some generic properties that, under some circumstances, make them not only mildly preferable over electromagnets, but make it possible to do things that can not be done with any other technology. After a general discussion of these generic advantages, some specific permanent magnet systems will be described. Special emphasis will be placed on systems that have now, or are likely to have in the future, a significant impact on how some materials research is conducted. 4 refs., 33 figs

  2. Permanent-magnet material applications in particle accelerators

    International Nuclear Information System (INIS)

    Kraus, R.H. Jr.

    1992-01-01

    The modern charged particle accelerator has found application in a wide range of scientific research, industrial, medical, and defense fields. Researchers began to use permanent-magnet materials in particle accelerators soon after the invention of the alternating gradient principle, which showed that magnetic field could be used to control the transverse envelope of charged particle beams. The history of permanent-magnet use in accelerator physics and technology is outlined, current design methods and material properties of concern for particle accelerator applications are reviewed

  3. Comparison of adjustable permanent magnetic field sources

    DEFF Research Database (Denmark)

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

    2010-01-01

    be altered are analyzed using numerical simulations, and compared based on the generated magnetic flux density in a sample volume and the amount of magnet material used. The designs are the concentric Halbach cylinder, the two half Halbach cylinders, the two linear Halbach arrays and the four and six rod...... and the direction of the magnetic field are measured and compared with numerical simulation and a good agrement is found....

  4. Potential uses of high gradient magnetic filtration for high-temperature water purification in boiling water reactors

    International Nuclear Information System (INIS)

    Elliott, H.H.; Holloway, J.H.; Abbott, D.G.

    1979-01-01

    Studies of various high-temperature filter devices indicate a potentially positive impact for high gradient magnetic filtration on boiling water reactor radiation level reduction. Test results on in-plant water composition and impurity crystallography are presented for several typical boiling water reactors (BWRs) on plant streams where high-temperature filtration may be particularly beneficial. An experimental model on the removal of red iron oxide (hematite) from simulated reactor water with a high gradient magnetic filter is presented, as well as the scale-up parameters used to predict the filtration efficiency on various high temperature, in-plant streams. Numerical examples are given to illustrate the crud removal potential of high gradient magnetic filters installed at alternative stream locations under typical, steady-state, plant operating conditions

  5. 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.

  6. Estimation of parameters of interior permanent magnet synchronous motors

    International Nuclear Information System (INIS)

    Hwang, C.C.; Chang, S.M.; Pan, C.T.; Chang, T.Y.

    2002-01-01

    This paper presents a magnetic circuit model to the estimation of machine parameters of an interior permanent magnet synchronous machine. It extends the earlier work of Hwang and Cho that focused mainly on the magnetic aspects of motor design. The proposed model used to calculate EMF, d- and q-axis reactances. These calculations are compared to those from finite element analysis and measurement with good agreement

  7. NdFeB permanent magnets with various Nd content

    Czech Academy of Sciences Publication Activity Database

    Žák, Tomáš; Talijan, N.; Ćosović, V.; Grujić, A.

    2008-01-01

    Roč. 113, č. 1 (2008), s. 279-282 ISSN 0587-4246. [Czech and Slovak Conference on Magnetism /13./ (CSMAG'07). Košice, 09.08.2007-12.08.2007] R&D Projects: GA MŠk 1M0512 Institutional research plan: CEZ:AV0Z20410507 Keywords : NdFeB permanent magnets * Mossbauer effect * X-ray Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.321, year: 2008

  8. Estimation of parameters of interior permanent magnet synchronous motors

    CERN Document Server

    Hwang, C C; Pan, C T; Chang, T Y

    2002-01-01

    This paper presents a magnetic circuit model to the estimation of machine parameters of an interior permanent magnet synchronous machine. It extends the earlier work of Hwang and Cho that focused mainly on the magnetic aspects of motor design. The proposed model used to calculate EMF, d- and q-axis reactances. These calculations are compared to those from finite element analysis and measurement with good agreement.

  9. Streaming flows produced by oscillating interface of magnetic fluid adsorbed on a permanent magnet in alternating magnetic field

    Science.gov (United States)

    Sudo, S.; Ito, M.; Ishimoto, Y.; Nix, S.

    2017-04-01

    This paper describes microstreaming flows generated by oscillating interface of magnetic fluid adsorbed on a circular cylindrical permanent magnet in alternating magnetic field. The interface of magnetic fluid adsorbed on the NdFeB magnet responds to the external alternating magnetic flied as harmonic oscillation. The directions of alternating magnetic field are parallel and antiparallel to the magnetic field of permanent magnet. The oscillation of magnetic fluid interface generates streaming flow around the magnet-magnetic fluid element in water. Microstreaming flows are observed with a high-speed video camera analysis system. The flow pattern generated by magnetic fluid motion depends on the Keulegan-Carpenter number and the Reynolds number.

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

    International Nuclear Information System (INIS)

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

    2006-01-01

    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 < 30 K. An electronic DC-DC converter was built in order to control the energy flow in and out of the superconducting coil. The converter consists of a MOS transistor bridge switching at a 80 kHz frequency and controlled with standard Pulse Width Modulation (PWM) techniques. The system was tested using a 30 V squared wave 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

  11. 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.

  12. Design and characterization of permanent magnetic solenoids for REGAE

    International Nuclear Information System (INIS)

    Hachmann, M.; Flöttmann, K.; Gehrke, T.; Mayet, F.

    2016-01-01

    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.

  13. High temperature annealing effect on structural and magnetic properties of Ti/Ni multilayers

    International Nuclear Information System (INIS)

    Bhatt, Pramod; Ganeshan, V.; Reddy, V.R.; Chaudhari, S.M.

    2006-01-01

    High temperature annealing effect on structural and magnetic properties of Ti/Ni multilayer (ML) up to 600 deg. C have been studied and reported in this paper. Ti/Ni multilayer samples having constant layer thicknesses of 50 A each are deposited on float glass and Si(1 1 1) substrates using electron-beam evaporation technique under ultra-high vacuum (UHV) conditions at room temperatures. The micro-structural parameters and their evolution with temperature for as-deposited as well as annealed multilayer samples up to 600 deg. C in a step of 100 deg. C for 1 h are determined by using X-ray diffraction (XRD) and grazing incidence X-ray reflectivity techniques. The X-ray diffraction pattern recorded at 300 deg. C annealed multilayer sample shows interesting structural transformation (from crystalline to amorphous) because of the solid-state reaction (SSR) and subsequent re-crystallization at higher temperatures of annealing, particularly at ≥400 deg. C due to the formation of TiNi 3 and Ti 2 Ni alloy phases. Sample quality and surface morphology are examined by using atomic force microscopy (AFM) technique for both as-deposited as well as annealed multilayer samples. In addition to this, a temperature dependent dc resistivity measurement is also used to study the structural transformation and subsequent alloy phase formation due to annealing treatment. The corresponding magnetization behavior of multilayer samples after each stage of annealing has been investigated by using Magneto-Optical Kerr Effect (MOKE) technique and results are interpreted in terms of observed micro-structural changes

  14. Study of the implementation of high temperature superconductors to accelerator magnets

    International Nuclear Information System (INIS)

    Fleiter, Jerome

    2013-01-01

    Particle colliders are the main tool for investigating and understanding the fundamental laws of physics. The CERN Large Hadron Collider (LHC), is a circular accelerator which steers and collides two counter-rotating protons beams. It has four collision points where detectors are placed to analyze the products emerging from the collisions. In a synchrotron machine a magnetic flux density is used to guide and focus particles around the orbit. The maximum energy that a circular machine with a given geometry can achieve is limited by the maximum strength of the dipole magnetic flux density. There is therefore an interest in the particle physics community in searching for dipole magnets with higher strength. The LHC has a beam trajectory radius of 4.3 km and a collision center-of-mass energy of 14 TeV. The accelerator employs 1232 large superconducting Nb-Ti dipole magnets operated at a flux density of up to 8.3 T in a bath of superfluid helium at 1.9 K. Energies higher than that achieved with the LHC require magnets made from superconductors with higher upper critical flux density. Nb 3 Sn is an option for magnets operated up to about 14 T. The level of energies of the type being discussed for a potential energy upgrade of the LHC machine - 33 TeV- would require the use of high temperature superconductors (HTS). Three technical HTS are available today: YBCO, Bi-2212 and Bi-2223. At low temperature YBCO conductors present both irreversible flux density and current density in excess of those measured in Bi-2212 and Bi-2223 conductors. In addition, YBCO can be used as reacted conductor, which makes its use for applications simpler than Bi-2212, which requires heat treatment at high temperature and in oxygen atmosphere after cabling and winding. The level of currents required for application to accelerator magnets, which is above 10 kA at the nominal operating temperature and flux density, excludes the use of single strands. The high current and high current density

  15. 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.

  16. 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.

  17. Novel ocean energy permanent magnet linear generator buoy

    Energy Technology Data Exchange (ETDEWEB)

    Rhinefrank, K.; Agamloh, E.B.; Jouanne, A. von; Wallace, A.K.; Prudell, J.; Kimble, K.; Aills, J.; Schmidt, E.; Schacher, A. [School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331-3211 (United States); Chan, P.; Sweeny, B. [Department of Mechanical Engineering, Oregon State University, Corvallis, OR 97331-3211 (United States)

    2006-07-15

    This paper describes the research, design, construction and prototype testing process of a novel ocean energy direct drive permanent magnet linear generator buoy. The buoy employs the vertical component of the motion of ocean waves to power a linear generator. The generator consists of a permanent magnet field system (mounted on the central translator shaft) and an armature, in which the power is generated (mounted on the buoy). The translator shaft is anchored to the sea floor, and the buoy/floater moves armature coils relative to the permanent magnet translator to induce voltages. The electrical and mechanical structures of the buoy generator are provided, along with performance characteristics, including voltage, current and developed power. (author)

  18. 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.

  19. Permanent Magnetic System Design for the Wall-Climbing Robot

    Directory of Open Access Journals (Sweden)

    W. Shen

    2006-01-01

    Full Text Available This paper presents the design and analysis of the permanent magnetic system for a wall-climbing robot with permanent magnetic tracks. Based on the behaviour of gecko lizards, the architecture of the robot was designed and built, including the structure of the adhesion mechanism, the mechanical architecture and the anti-toppling mechanism. The permanent magnetic adhesion mechanism and the tracked locomotion mechanism were employed in this kind of wall-climbing robot. Through static and dynamic force analysis of the robot under different situations, design requirements for the adhesion mechanism were derived. Two different types of structures were put forward for the permanent magnetic units and are further discussed in this paper. These two types of structures are also analysed in detail. In addition, a finite-element method was used to verify the results of magnetic units. Finally, two wall-climbing robots, equipped with different magnetic systems described previously, are explained and their applications are discussed in this paper.

  20. Experiences with permanent magnets at the Fermilab recycler ring

    International Nuclear Information System (INIS)

    Volk, James T

    2011-01-01

    In order to achieve higher luminosities in Run II a separate antiproton storage ring was built in the Main Injector tunnel. To reduce both construction and operations costs permanent magnets were used. This paper discusses the design criterion and specifications, including temperature dependence, longitudinal uniformity, and adjusting of the higher harmonics of the magnets. The design tolerances for a storage ring are more stringent than for a single pass beam line. The difference between the measured and ideal central field for each magnet was held to better than 0.1%. The temperature stability for all magnets was set to better than 0.01% per degree Celsius. Higher order harmonics relative to the central field were set to less than 0.01%. This was done for all 484 permanent magnet that were built.

  1. Variable-field permanent-magnet quadrupole for the SSC

    International Nuclear Information System (INIS)

    Barlow, D.B.; Kraus, R.H. Jr.; Martinez, R.P.; Meyer, R.E.

    1994-01-01

    A set of compact variable-field permanent-magnet quadrupoles have been designed, fabricated, and tested for use in the SSC linac matching section. The quadrupoles have 24 mm-diameter apertures and 40 mm-long poles. The hybrid (permanent-magnet and iron) design, uses a fixed core of magnet material (NdFeB) and iron (C-1006) surrounded by a rotating ring of the same magnet material and iron. The quadrupole gradient-length product can be smoothly varied from a minimum of 0.7 T up to a maximum of 4.3 T by a 90 degree rotation of the outer ring of iron and magnet material

  2. Hybrid-secondary uncluttered permanent magnet machine and method

    Science.gov (United States)

    Hsu, John S.

    2005-12-20

    An electric machine (40) has a stator (43), a permanent magnet rotor (38) with permanent magnets (39) and a magnetic coupling uncluttered rotor (46) for inducing a slip energy current in secondary coils (47). A dc flux can be produced in the uncluttered rotor when the secondary coils are fed with dc currents. The magnetic coupling uncluttered rotor (46) has magnetic brushes (A, B, C, D) which couple flux in through the rotor (46) to the secondary coils (47c, 47d) without inducing a current in the rotor (46) and without coupling a stator rotational energy component to the secondary coils (47c, 47d). The machine can be operated as a motor or a generator in multi-phase or single-phase embodiments and is applicable to the hybrid electric vehicle. A method of providing a slip energy controller is also disclosed.

  3. A variable-field permanent-magnet dipole for accelerators

    International Nuclear Information System (INIS)

    Kraus, R.H. Jr.; Barlow, D.B.; Meyer, R.

    1992-01-01

    A new concept for a variable-field permanent-magnet dipole has been developed and fabricated at Los Alamos. The application requires an extremely uniform dipole field in the magnet aperture and precision variability over a large operating range. An iron-core permanent- magnet design using a shunt that was specially shaped to vary the field in a precise and reproducible fashion with shunt position. The key to this design is in the shape of the shunt. The field as a function of shunt position is very linear from 90% of the maximum field to 20% of the minimum field. The shaped shunt also results in a small maximum magnetic force attracting the shunt to the yoke allowing a simple mechanical design. Calculated and measured results agree well for the magnet

  4. Variable-field permanent magnet quadrupole for the SSC

    International Nuclear Information System (INIS)

    Barlow, D.B.; Kraus, R.H. Jr.; Martinez, R.P.; Meyer, R.E.

    1993-01-01

    A set of compact variable-field permanent-magnet quadrupoles have been designed, fabricated, and tested for use In the SSC linac matching section. The quadrupoles have 24 mm-diameter apertures and 40 mm-long poles. The hybrid (permanent-magnet and iron) design, uses a fixed core of magnet material (NdFeB) and iron (C-1006) surrounded by a rotating ring of the same magnet material and iron. The quadrupole gradient-length product can be smoothly varied from a minimum of 0.7 T up to a maximum, of 4.3 T by a 90 degrees rotation of the outer ring of iron and magnet material

  5. First Results from Tests of High Temperature Superconductor Magnets on Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Gryaznevich, M.; Todd, T.T., E-mail: mikhail.gryaznevich@ccfe.ac.uk [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon (United Kingdom); Svoboda, V.; Markovic, T.; Ondrej, G. [Czech Technical University, Prague (Czech Republic); Stockel, J.; Duran, I.; Kovarik, K. [IPP Prague, Czech Technical University, Prague (Czech Republic); Sykes, A.; Kingham, D. [Tokamak Solutions, Culham Science Centre, Abingdon (United Kingdom); Melhem, Z.; Ball, S.; Chappell, S. [Oxford Instruments, Abingdon (United Kingdom); Lilley, M. K.; De Grouchy, P.; Kim, H. -T. [Imperial College, London (United Kingdom)

    2012-09-15

    Full text: It has long been known that high temperature superconductors (HTS) could have an important role to play in the future of tokamak fusion research. Here we report on first results of the use of HTS in a tokamak magnet and on the progress in design and construction of the first fully-HTS tokamak. In the experiment, the two copper vertical field coils of the small tokamak GOLEM were replaced by two coils each with 6 turns of HTS (Re)BCO tape. Liquid nitrogen was used to cool the coils to below the critical temperature at which HTS becomes superconducting. Little effect on the HTS critical current has been observed for perpendicular field up to 0.5 T and superconductivity has been achieved at {approx} 90.5K during bench tests. There had been concerns that the plasma pulses and pulsed magnetic fields might cause a 'quench' in the HTS, i.e., a sudden and potentially damaging transition from superconductor to normal conductor. However, many plasma pulses were fired without any quenches even when disruptions occurred with corresponding induced electrical fields. In addition, experiments without plasma have been performed to study properties of the HTS in a tokamak environment, i.e., critical current and its dependence on magnetic and electrical fields generated in a tokamak both in DC and pulsed operations, maximum current ramp-up speed, performance of the HTS tape after number of artificially induced quenches etc. No quench has been observed at DC currents up to 200 A (1.2 kA-turns through the coil). In short pulses, current up to 1 kA through the tape (6 kA-turns) has been achieved with no subsequent degradation of the HTS performance with a current ramp rate up to 0.6 MA/s. In future experiments, increases in both the plasma current and pulse duration are planned. Considerable experience has been gained during design and fabrication of the cryostat, coils, isolation and insulation, feeds and cryosystems, and GOLEM is now routinely operated with HTS coils. The

  6. Controlling chaos in the permanent magnet synchronous motor

    International Nuclear Information System (INIS)

    Zribi, Mohamed; Oteafy, Ahmed; Smaoui, Nejib

    2009-01-01

    The Permanent Magnet Synchronous Motor (PMSM) is known to exhibit chaotic behavior under certain conditions. This paper proposes to use an instantaneous Lyapunov exponent control algorithm to control the PMSM. One of the objectives of the control approach is to bring order to the PMSM and to drive it to any user-defined desired state. Simulation results under different operating conditions indicate that the proposed control scheme works well. Moreover, the proposed Lyapunov exponent control scheme is able to induce chaos on the permanent magnet synchronous motor. Simulation results show the effectiveness of the proposed control scheme in chaotifing the response of the motor.

  7. Tests of planar permanent magnet multipole focusing elements

    International Nuclear Information System (INIS)

    Cobb, J.; Tatchyn, R.

    1993-08-01

    In recent work, planar configurations of permanent magnets were proposed as substitutes for conventional current-driven iron quadrupoles in applications limited by small aperture sizes and featuring small beam occupation diameters. Important examples include the configuring of focusing lattices in small-gap insertion devices, and the implementation of compact mini-beta sections on linear or circular machines. In subsequent analysis, this approach was extended to sextupoles and higher-order multipoles. In this paper we report on initial measurements conducted at the Stanford Linear Accelerator Center on recently fabricated planar permanent magnet quadrupoles and sextupoles configured out of SmCo and NdFe/B

  8. 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.

  9. Design Considerations of Permanent Magnet Transverse Flux Machines

    DEFF Research Database (Denmark)

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

    2011-01-01

    electrical machines. This paper addresses two important design considerations for PMTFM—the influence of permanent magnet leakage flux, which plays an important role in the determination of machine output torque, and the leakage inductance. A new simple method to provide a quick estimation of the armature......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...

  10. Investigation of permanent magnet machines for downhole applications: Design, prototype and testing of a flux-switching permanent magnet machine

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Anyuan

    2011-01-15

    The current standard electrical downhole machine is the induction machine which is relatively inefficient. Permanent magnet (PM) machines, having higher efficiencies, higher torque densities and smaller volumes, have widely employed in industrial applications to replace conventional machines, but few have been developed for downhole applications due to the high ambient temperatures in deep wells and the low temperature stability of PM materials over time. Today, with the development of variable speed drives and the applications of high temperature magnet materials, it is increasingly interesting for oil and gas industries to develop PM machines for downhole applications. Recently, some PM machines applications have been presented for downhole applications, which are normally addressed on certain specific downhole case. In this thesis the focus has been put on the performance investigation of different PM machines for general downhole cases, in which the machine outer diameter is limited to be small by well size, while the machine axial length may be relatively long. The machine reliability is the most critical requirement while high torque density and high efficiency are also desirable. The purpose is to understand how the special constraints in downhole condition affect the performances of different machines. First of all, three basic machine concepts, which are the radial, axial and transverse flux machines, are studied in details by analytical method. Their torque density, efficiency, power factor and power capability are investigated with respect to the machine axial length and pole number. The presented critical performance comparisons of the machines provide an indication of machines best suitable with respect to performance and size for downhole applications. Conventional radial flux permanent magnet (RFPM) machines with the PMs on the rotor can provide high torque density and high efficiency. This type of machine has been suggested for several different

  11. Investigation of the magnetic field of the permanent magnet applied in the DIRAC experiment

    CERN Document Server

    Batyuk, P; Yazkov, V

    2012-01-01

    An analysis of the experimental data obtained during the run of 2011 has revealed the effect of degradation of the permanent magnet used. This effect is investigated, and average magnetic field is estimated for each day of the run.

  12. 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.

  13. 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.

  14. 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. PMID:25050388

  15. 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. 

  16. 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

  17. 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.

  18. Non linear permanent magnets modelling with the finite element method

    International Nuclear Information System (INIS)

    Chavanne, J.; Meunier, G.; Sabonnadiere, J.C.

    1989-01-01

    In order to perform the calculation of permanent magnets with the finite element method, it is necessary to take into account the anisotropic behaviour of hard magnetic materials (Ferrites, NdFeB, SmCo5). In linear cases, the permeability of permanent magnets is a tensor. This one is fully described with the permeabilities parallel and perpendicular to the easy axis of the magnet. In non linear cases, the model uses a texture function which represents the distribution of the local easy axis of the cristallytes of the magnet. This function allows a good representation of the angular dependance of the coercitive field of the magnet. As a result, it is possible to express the magnetic induction B and the tensor as functions of the field and the texture parameter. This model has been implemented in the software FLUX3D where the tensor is used for the Newton-Raphson procedure. 3D demagnetization of a ferrite magnet by a NdFeB magnet is a suitable representative example. They analyze the results obtained for an ideally oriented ferrite magnet and a real one using a measured texture parameter

  19. Permanent magnet steerers for canted undulators at the ESRF

    Energy Technology Data Exchange (ETDEWEB)

    Le Bec, G., E-mail: lebec@esrf.fr [ESRF, 6 r. J. Horowitz, BP 220, 38043 Grenoble Cedex 9 (France); Chavanne, J. [ESRF, 6 r. J. Horowitz, BP 220, 38043 Grenoble Cedex 9 (France)

    2012-02-01

    A number of canted undulators will be installed at the ESRF. Permanent Magnet Steerers will be used for providing canting angles up to 5.4 mrad. These steerers have been optimized in view of the limited space available and the required field quality. The magnetic interaction between the steerers and the undulators may lead to additional optical phase errors: auxiliary poles have been added to obtain a fast decrease of the fringe field. The transverse homogeneity of the magnetic field integral is another strong design constraint. Good homogeneity was reached by optimizing the profiles of the iron poles. Eight steerers have been constructed and magnetic measurements have been performed.

  20. High speed operation of permanent magnet machines

    Science.gov (United States)

    El-Refaie, Ayman M.

    This work proposes methods to extend the high-speed operating capabilities of both the interior PM (IPM) and surface PM (SPM) machines. For interior PM machines, this research has developed and presented the first thorough analysis of how a new bi-state magnetic material can be usefully applied to the design of IPM machines. Key elements of this contribution include identifying how the unique properties of the bi-state magnetic material can be applied most effectively in the rotor design of an IPM machine by "unmagnetizing" the magnet cavity center posts rather than the outer bridges. The importance of elevated rotor speed in making the best use of the bi-state magnetic material while recognizing its limitations has been identified. For surface PM machines, this research has provided, for the first time, a clear explanation of how fractional-slot concentrated windings can be applied to SPM machines in order to achieve the necessary conditions for optimal flux weakening. A closed-form analytical procedure for analyzing SPM machines designed with concentrated windings has been developed. Guidelines for designing SPM machines using concentrated windings in order to achieve optimum flux weakening are provided. Analytical and numerical finite element analysis (FEA) results have provided promising evidence of the scalability of the concentrated winding technique with respect to the number of poles, machine aspect ratio, and output power rating. Useful comparisons between the predicted performance characteristics of SPM machines equipped with concentrated windings and both SPM and IPM machines designed with distributed windings are included. Analytical techniques have been used to evaluate the impact of the high pole number on various converter performance metrics. Both analytical techniques and FEA have been used for evaluating the eddy-current losses in the surface magnets due to the stator winding subharmonics. Techniques for reducing these losses have been

  1. Magnetic levitation force between a superconducting bulk magnet and a permanent magnet

    International Nuclear Information System (INIS)

    Wang, J J; He, C Y; Meng, L F; Li, C; Han, R S; Gao, Z X

    2003-01-01

    The current density J(ρ, z) in a disc-shaped superconducting bulk magnet and the magnetic levitation force F SBM z exerted on the superconducting bulk magnet by a cylindrical permanent magnet are calculated from first principles. The effect of the superconducting parameters of the superconducting bulk is taken into account by assuming the voltage-current law E = E c (J/J c ) n and the material law B = μ 0 H. The magnetic levitation force F SBM z is dominated by the remnant current density J' 2 (ρ, z), which is induced by switching off the applied magnetizing field. High critical current density and flux creep exponent may increase the magnetic levitation force F SBM z . Large volume and high aspect ratio of the superconducting bulk can further enhance the magnetic levitation force F SBM z

  2. 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.

  3. 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.

  4. Corrosion behaviour of Nd-Fe-B permanent magnets

    International Nuclear Information System (INIS)

    Mummert, K.; El-Aziz, A.M.; Barkleit, G.; Schultz, L.; Rodewald, W.

    2000-01-01

    The corrosion behaviour of Nd-Fe-B permanent magnetic alloys as well as of single phases of these alloys have been investigated in sulphuric acid at room temperature and humid air at 150 C using mass loss and electrochemical techniques. Scanning electron microscopy and scanning probe microscopy were used to study the surface topography. The electrostatic surface potential was examined by scanning probe microscopy using tapping mode. A correlation between the electrostatic surface potential and the corrosion rate of these alloys was found. The higher the value of the electrostatic surface potential of the intergranular phases the higher is the corrosion sensitivity. The strength of the corrosion attack on the phases of sintered permanent magnetic alloys is as follows: Ferromagnetic phase < B-rich phase < Nd-rich phase. The differences in the chemical composition as well as in the preparation of these magnetic alloys have distinct influence on the corrosion resistance of the magnetic Nd-Fe-B alloys. (orig.)

  5. Rational design of the exchange-spring permanent magnet

    International Nuclear Information System (INIS)

    Jiang, J S; Bader, S D

    2014-01-01

    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. (paper)

  6. 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.

  7. Cluster-Expansion Model for Complex Quinary Alloys: Application to Alnico Permanent Magnets

    Science.gov (United States)

    Nguyen, Manh Cuong; Zhou, Lin; Tang, Wei; Kramer, Matthew J.; Anderson, Iver E.; Wang, Cai-Zhuang; Ho, Kai-Ming

    2017-11-01

    An accurate and transferable cluster-expansion model for complex quinary alloys is developed. Lattice Monte Carlo simulation enabled by this cluster-expansion model is used to investigate temperature-dependent atomic structure of alnico alloys, which are considered as promising high-performance non-rare-earth permanent-magnet materials for high-temperature applications. The results of the Monte Carlo simulations are consistent with available experimental data and provide useful insights into phase decomposition, selection, and chemical ordering in alnico. The simulations also reveal a previously unrecognized D 03 alloy phase. This phase is very rich in Ni and exhibits very weak magnetization. Manipulating the size and location of this phase provides a possible route to improve the magnetic properties of alnico, especially coercivity.

  8. MODELING OF TRACTION SYNCHRONOUS PERMANENT MAGNET MOTOR MODES

    Directory of Open Access Journals (Sweden)

    Y.N. Vas’kovsky

    2013-10-01

    Full Text Available A mathematical model of electromagnetic field for simulating operational modes of traction synchronous motors with permanent magnets intended for electric vehicles is developed. The mathematical model takes into account real-time rotor rotation and allows calculating and analyzing the motor basic running characteristics as time functions.

  9. Nonlinear control of permanent magnet synchronous motor driving a ...

    African Journals Online (AJOL)

    This paper presents a non-linear control of permanent magnet synchronous motor (PMSM) fed by a PWM voltage source inverter. To improve the performance of this control technique, the input-output linearization technique is proposed for a system driving a mechanical load with two masses. In order to ensure a steady ...

  10. Resonant inverter supplied Interior Permanent Magnet (IPM) motor ...

    African Journals Online (AJOL)

    In this paper, rotor position in relation to the resonant frequency component current in the stator winding of DC-voltage link resonant inverter supplied Interior Permanent Magnet (IPM) motor has been developed. Six reference frames are used to relate the rotor position angle to the resonant frequency component current ...

  11. Force measurements on a shielded coreless linear permanent magnet motor

    NARCIS (Netherlands)

    Pluk, K.J.W.; Jansen, J.W.; Lomonova, E.A.

    2014-01-01

    This paper compares force measurements on a shielded coreless linear permanent magnet motor with 2-D models. A 2-D semianalytical modeling method is applied, which is based on Fourier modeling and includes force calculations. The semianalytical modeling correctly predicts the behavior found in the

  12. Failure Diagnosis for Demagnetization in Interior Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Takeo Ishikawa

    2017-01-01

    Full Text Available Since a high degree of reliability is necessary for permanent magnet synchronous motors, the detection of a precursor for the demagnetization of permanent magnets is very important. This paper investigates the diagnosis of very slight PM demagnetization. The permanent magnet volume is altered so as to mimic the effect of demagnetization. This paper investigates the influence of demagnetization by using several methods: the 3D finite element analysis (FEA of the motor, the measurement of high-frequency impedance, and the measurement and FEA of the stator voltage and current under vector control. We have obtained the following results. The back-EMF is proportional to permanent magnet volume, and there is no difference in the demagnetization in the radial direction and in the axial direction. Even harmonics and subharmonics of flux density at the teeth tip could be useful for diagnosis if a search coil is installed there. The relatively low frequency resistance at the d-axis position is useful for diagnosis. Under vector control, the stator voltage is useful except in an intermediate torque range, and the intermediate torque is expressed by a simple equation.

  13. Comparative analysis of various methods for modelling permanent magnet machines

    NARCIS (Netherlands)

    Ramakrishnan, K.; Curti, M.; Zarko, D.; Mastinu, G.; Paulides, J.J.H.; Lomonova, E.A.

    2017-01-01

    In this paper, six different modelling methods for permanent magnet (PM) electric machines are compared in terms of their computational complexity and accuracy. The methods are based primarily on conformal mapping, mode matching, and harmonic modelling. In the case of conformal mapping, slotted air

  14. Slotless brushless permanent magnet motor and winding topologies

    International Nuclear Information System (INIS)

    Chen, Y.S.; Zhu, Z.Q.; Howe, D.; Hu, G.F.

    1998-01-01

    In the paper, the merits of alternative slotless brushless permanent magnet motor and winding topologies are investigated, using 2-D analytical models embodied with CAD design software. The design optimisation of both internal and external rotor motors, with and without stator back-iron, and with either overlapping or non-overlapping winding, is considered. (orig.)

  15. Nanocomposite permanent magnetic materials Nd-Fe-B type: The influence of nanocomposite on magnetic properties

    Directory of Open Access Journals (Sweden)

    Talijan Nadežda M.

    2005-01-01

    Full Text Available The influence on the magnetic properties of nanocristalline ribbons and powders has character of microstructure, between others – the grain size volume of hard and soft magnetic phases and their distribution. Magnetic properties of ribbons and powders depend mainly on their chemical composition and parameters of their heat treatment [1]. Technology of magnets from nanocristalline ribbon consists of the following process: preparing the Nd-Fe- B alloy, preparing the ribbon, powdering of the ribbon, heat treatment of the powder and finally preparing the magnets. Nanocomposite permanent magnet materials based on Nd-Fe- B alloy with Nd low content are a new type of permanent magnetic material. The microstructure of this nanocomposite permanent magnet is composed of a mixture of magnetically soft and hard phases which provide so called exchange coupling effect.

  16. Axial magnetic field produced by axially and radially magnetized permanent rings

    International Nuclear Information System (INIS)

    Peng, Q.L.; McMurry, S.M.; Coey, J.M.D.

    2004-01-01

    Axial magnetic fields produced by axially and radially magnetized permanent magnet rings were studied. First, the axial magnetic field produced by a current loop is introduced, from which the axial field generated by an infinitely thin solenoid and by an infinitely thin current disk can be derived. Then the axial fields produced by axially and by radially magnetized permanent magnet rings can be obtained. An analytic formula for the axial fields produced by two axially magnetized rings is given. A permanent magnet with a high axial gradient field is fabricated, the measured results agree with the theoretical calculation very well. As an example, the axial periodic field produced by an arrangement of alternating axially and radially magnetized rings has been discussed

  17. Cobalt-Free Permanent Magnet Alloys.

    Science.gov (United States)

    1984-10-01

    ThC Ferrites (Zn, Mn. Cu, Fe)O A12O. Al TiC Kaolin Al203.Si02-Fe2O3 Fe2O3 Li B4C Spodumene LiAI (SiOs) 2 ThO2 Ni UC Rhodonite NtnO. SiO2 MnOs Fe TaC...minutes. X-ray diffraction pattern indicated the presence of magnetic T phase. Hysteresis loop was measured on the heat treated powder dispersed in wax...fmgei * T phse Hysersi loo was mesue on the. heat - treated ,--". " powder dispersed in wax... The’ result wer as"- follows: • , " • "• . I TABLE 6

  18. A superconducting solenoid and press for permanent magnet fabrication

    International Nuclear Information System (INIS)

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

    2002-01-01

    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. Compaction was achieved by pressing the punches between the closed end of the press tube and the hydraulic cylinder mounted on the opposite end. Improvements up to 10% in magnetization and 20% in energy products of the permanent magnets were obtained, as the alignment fields were increased above the 2-T maximum field of the electromagnets used in industry. Increases in magnetization of 3% are significant in the mature sintered magnet industry

  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. Calculation and Analysis of Permanent Magnet Eddy Current Loss Fault with Magnet Segmentation

    Directory of Open Access Journals (Sweden)

    Bing Li

    2016-01-01

    Full Text Available This paper investigates the problem of calculating and analyzing the effect of the permanent magnet eddy current loss fault due to magnet segmentation. Taking an interior permanent magnet synchronous motor with inverter supplied as an example, the rated power of motor was 2.2 kW. Three-dimensional finite-element model was firstly established based on finite-element software. Then, the model mesh and boundary conditions were handled specially; permanent magnet eddy current loss fault was calculated and analyzed theoretically with magnet segmentation from space harmonic and time harmonic, respectively. Finally, calculation results were compared and explained. A useful conclusion for permanent magnet synchronous motor design has been obtained.

  1. 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.

  2. Wind turbine integrated multipole permanent magnet generator (PMG)

    Energy Technology Data Exchange (ETDEWEB)

    Vilsboell, N.; Pinegin, A.; Goussarov, D.

    1996-01-01

    Designed permanent magnet generator (PMG - 20 kW) possesses a number of advantages: it makes possible to replace gearbox, the generator and possibly the hub of the wind turbine by combining wind rotor with external rotor of the generator; use of rare earth magnets Nd-Fe-B allows to reduce mass and dimensions of the generator; use of the PMG for wind turbines increases the reliability of the construction during the life time, comparing to the conventional design (gearbox, asynchronous generator). The test of the PMG -20 kW informs that design method, developed for calculation of multipole permanent magnet generators is correct in general and meets engineering requirements. The calculation uncertainty of the magnetic system and output characteristics does not exceed 2-3%. The test shows, that the maximum efficiency of the PGM - 20 kW with full load can be achieved as high as 90-91.5% and excels the efficiency of the traditional system `generator-gearbox` by 4-5.5%. Designing permanent magnet generator, it is recommended to take into account voltage stabilization (capacitance). Efficiency is expected to be higher, mass and production cost of the generator can be reduced by 25-30%. The frequency converter shall be used not only for control of rotational speed, but also to obtain sinusoidal capacitive current on the generator side. For PMG - 20 kW the angle between voltage and current should be within the range 0-23%. (au)

  3. A review of radiation-induced demagnetization of permanent magnets

    Science.gov (United States)

    Samin, Adib J.

    2018-05-01

    Radiation-induced demagnetization of permanent magnets is important for a number of applications including space missions, particle accelerators and robots designed to carry out rescue missions at nuclear accidents where magnet failure can lead to serious consequences. This topic has been studied by several investigators over the past three decades and in this work, a review of the available literature is conducted and some general conclusions and trends are presented. In short, it can be gleaned that magnetism loss is dependent on the type of radiation, the energy of the incoming particle and the overall dose or fluence. Furthermore, magnetism loss also shows a dependence on the type of the irradiated magnet, the coercivity of the magnet, the demagnetizing field and the temperature of irradiation.

  4. 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 speci......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....

  5. 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. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Samarium-cobalt-copper-iron-titanium permanent magnets

    International Nuclear Information System (INIS)

    Inomata, K.; Yamada, M.

    1980-01-01

    A permanent magnet, which comprises a composition containing a Sm-Co compound and consisting essentially of 23 to 30 wt.% of Sm, 0.2 to 1.5 wt.% Ti, 9 to 13 wt., Cu, 3 to 12 wt.% Fe and the balance Co, said magnet having a residual flux density (Br) of about 10 (kG), a coercive force (IC) of about 8 (KOe) and a maximum energy product (BH max) of about 25 (MGOe), having the aforesaid magnetic properties without the necessity of an ageing treatment

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

    Czech Academy of Sciences Publication Activity Database

    Vokoun, David; Beleggia, M.

    2014-01-01

    Roč. 350, JAN (2014), s. 174-178 ISSN 0304-8853 R&D Projects: GA ČR(CZ) GAP107/11/0391; GA MŠk(CZ) LM2011026 Institutional support: RVO:68378271 Keywords : permanent magnet * cylindrical magnet * attraction force * magnetostatic interaction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.970, year: 2014 http://ac.els-cdn.com/S0304885313006732/1-s2.0-S0304885313006732-main.pdf?_tid=f6840b24-5115-11e3-9237-00000aab0f6b&acdnat=1384864232_323ac87712560a07

  8. High temperature refrigerator

    International Nuclear Information System (INIS)

    Steyert, W.A. Jr.

    1978-01-01

    A high temperature magnetic refrigerator is described which uses a Stirling-like cycle in which rotating magnetic working material is heated in zero field and adiabatically magnetized, cooled in high field, then adiabatically demagnetized. During this cycle the working material is in heat exchange with a pumped fluid which absorbs heat from a low temperature heat source and deposits heat in a high temperature reservoir. The magnetic refrigeration cycle operates at an efficiency 70% of Carnot

  9. Anomalous magneto-structural behavior of MnBi explained: A path towards an improved permanent magnet

    Energy Technology Data Exchange (ETDEWEB)

    Zarkevich, N. A., E-mail: zarkev@ameslab.gov; Wang, L.-L. [The Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011 (United States); Johnson, D. D. [The Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011 (United States); Materials Science and Engineering, Iowa State University, Ames, Iowa 50011 (United States)

    2014-03-01

    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.

  10. Anomalous magneto-structural behavior of MnBi explained: A path towards an improved permanent magnet

    Energy Technology Data Exchange (ETDEWEB)

    Zarkevich, NA; Wang, LL; Johnson, DD

    2014-03-01

    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. (C) 2014 Author(s).

  11. 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...

  12. Numerical simulation of magnetic convection ferrofluid flow in a permanent magnet-inserted cavity

    Science.gov (United States)

    Ashouri, Majid; Behshad Shafii, Mohammad

    2017-11-01

    The magnetic convection heat transfer in an obstructed two-dimensional square cavity is investigated numerically. The walls of the cavity are heated with different constant temperatures at two sides, and isolated at two other sides. The cavity is filled with a high Prandtl number ferrofluid. The convective force is induced by a magnetic field gradient of a thermally insulated square permanent magnet located at the center of the cavity. The results are presented in the forms of streamlines, isotherms, and Nusselt number for various values of magnetic Rayleigh numbers and permanent magnet size. Two major circulations are generated in the cavity, clockwise flow in the upper half and counterclockwise in the lower half. In addition, strong circulations are observed around the edges of the permanent magnet surface. The strength of the circulations increase monotonically with the magnetic Rayleigh number. The circulations also increase with the permanent magnet size, but eventually, are suppressed for larger sizes. It is found that there is an optimum size for the permanent magnet due to the contrary effects of the increase in magnetic force and the increase in flow resistance by increasing the size. By increasing the magnetic Rayleigh number or isothermal walls temperature ratio, the heat transfer rate increases.

  13. Magnetic field computations of the magnetic circuits with permanent magnets by infinite element method

    International Nuclear Information System (INIS)

    Hahn, Song Yop

    1985-01-01

    A method employing infinite elements is described for the magnetic field computations of the magnetic circuits with permanent magnet. The system stiffness matrix is derived by a variational approach, while the interfacial boundary conditions between the finite element regions and the infinite element regions are dealt with using collocation method. The proposed method is applied to a simple linear problems, and the numerical results are compared with those of the standard finite element method and the analytic solutions. It is observed that the proposed method gives more accurate results than those of the standard finite element method under the same computing efforts. (Author)

  14. On the motion of the field of a permanent magnet

    Energy Technology Data Exchange (ETDEWEB)

    Leus, Vladimir [Sobolev Institute of Mathematics, Novosibirsk (Russian Federation); Taylor, Stephen, E-mail: s.taylor@liv.ac.uk [Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool L69 3GJ (United Kingdom)

    2011-09-15

    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 and the area of the gap both remain constant. The experimental results are best explained by the fact that the magnetic field itself rotates with the rotating magnet. This is controversial in the scientific and educational literature, as shown by citations from various authors (e.g. Feynman, Tamm and Landau all disagree, and with each other). However, these experiments, which may be readily reproduced, do in fact settle the question.

  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

    2016-12-06

    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. 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.

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

    Science.gov (United States)

    Roesler, Alexander W [Tijeras, NM; Christenson, Todd R [Albuquerque, NM

    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.

  19. The electromagnetic design of a permanent magnet based separator

    International Nuclear Information System (INIS)

    Nedelcu, S.

    2002-08-01

    The aim of this work was to design a permanent magnet based device that can selectively transport paramagnetic particles. Using specialised electromagnetic design software various arrangements of permanent magnets have been investigated. Each test geometry had to be constructively simple and able to produce highly non-uniform magnetic fields before being considered further in any more detail. The main parameter to indicate that the test geometry might be a suitable device has been ascribed to the ratio η between the highest (ON) and lowest (OFF) magnetic fields that were measured. A linear arrangement of permanent magnets has been considered first. This device produced a ratio η ∼ 2. Further, the cylindrical and the tubular arrangements may be considered as substantial improvements over the first geometry. The OFF magnetic fields have been substantially reduced by the method of magnetic shielding. Intensive research and modelling has been spent on addressing the problem of finding the optimal geometry for such arrangements. An experimental system has been also built, and the experimental values were compared against the theory. However, the results produced evidence that the manufacturing of any improved geometry (an estimated η ∼ 100) in this direction might be very difficult, for the tolerances involved were very strict. The disk arrangement was the latest device to be investigated. Particularly, a magnetic dipole model developed earlier for the ring arrangement suggested the way in which to arrange the magnets in the ON position. Moreover, the use of the magnetic symmetry of the device forced the OFF magnetic fields to negligible values. Detailed computer simulations of the dynamics of the particles in the applied magnetic field of the tubular and disk arrangements have been earned out. The adopted models could show realistic phenomena, e.g. particle clustering, chaining, block movement, etc. The separation efficiency proved to be nearly 100%. For the

  20. System and method for preventing stator permanent magnet demagnetization during vacuum pressure impregnation

    Science.gov (United States)

    Raminosoa, Tsarafidy; Alexander, James Pellegrino; EL-Refaie, Ayman Mohamed Fawzi

    2017-06-06

    A permanent magnet electrical machine includes a stator having conductive windings wound thereon and one or more permanent magnets embedded in the stator. A magnetic keeper element is positioned on the stator so as to form a magnetic flux path with the permanent magnets, with the magnetic keeper element closing the magnetic flux path of the permanent magnets by providing a low reluctance flux path to magnetic flux generated by the permanent magnets. A vacuum pressure impregnation (VPI) process is performed on the stator to increase a thermal conductivity of the windings, with the VPI process including a curing step that is performed at a selected temperature. The magnetic keeper element sets an operating point of the permanent magnets to an internal flux density level above a demagnetization threshold associated with the selected temperature at which the curing step is performed.

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

    CERN Document Server

    Bayer, Christoph M

    2017-01-01

    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.

  2. 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.

  3. 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.

  4. Permanent magnet finger-size scanning electron microscope columns

    Energy Technology Data Exchange (ETDEWEB)

    Nelliyan, K., E-mail: elenk@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Khursheed, A. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore)

    2011-07-21

    This paper presents permanent magnet scanning electron microscope (SEM) designs for both tungsten and field emission guns. Each column makes use of permanent magnet technology and operates at a fixed primary beam voltage. A prototype column operating at a beam voltage of 15 kV was made and tested inside the specimen chamber of a conventional SEM. A small electrostatic stigmator unit and dedicated scanning coils were integrated into the column. The scan coils were wound directly around the objective lens iron core in order to reduce its size. Preliminary experimental images of a test grid specimen were obtained through the prototype finger-size column, demonstrating that it is in principle feasible.

  5. 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.

  6. Permanent magnet finger-size scanning electron microscope columns

    International Nuclear Information System (INIS)

    Nelliyan, K.; Khursheed, A.

    2011-01-01

    This paper presents permanent magnet scanning electron microscope (SEM) designs for both tungsten and field emission guns. Each column makes use of permanent magnet technology and operates at a fixed primary beam voltage. A prototype column operating at a beam voltage of 15 kV was made and tested inside the specimen chamber of a conventional SEM. A small electrostatic stigmator unit and dedicated scanning coils were integrated into the column. The scan coils were wound directly around the objective lens iron core in order to reduce its size. Preliminary experimental images of a test grid specimen were obtained through the prototype finger-size column, demonstrating that it is in principle feasible.

  7. 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

  8. 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.

  9. Disc rotors with permanent magnets for brushless DC motor

    Science.gov (United States)

    Hawsey, Robert A.; Bailey, J. Milton

    1992-01-01

    A brushless dc permanent magnet motor drives an autonomous underwater vehe. In one embodiment, the motor comprises four substantially flat stators in stacked relationship, with pairs of the stators axially spaced, each of the stators comprising a tape-wound stator coil, and first and second substantially flat rotors disposed between the spaced pairs of stators. Each of the rotors includes an annular array of permanent magnets embedded therein. A first shaft is connected to the first rotor and a second, concentric shaft is connected to the second rotor, and a drive unit causes rotation of the two shafts in opposite directions. The second shaft comprises a hollow tube having a central bore in which the first shaft is disposed. Two different sets of bearings support the first and second shafts. In another embodiment, the motor comprises two ironless stators and pairs of rotors mounted on opposite sides of the stators and driven by counterrotating shafts.

  10. 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.

  11. Water flow patterns induced by bridge oscillation of magnetic fluid between two permanent magnets subjected to alternating magnetic field

    International Nuclear Information System (INIS)

    Sudo, Seiichi; Yamamoto, Kazuki; Ishimoto, Yukitaka; Nix, Stephanie

    2017-01-01

    This paper describes the characteristics of water flow induced by the bridge oscillation of magnetic fluid between two permanent magnets subject to an external alternating magnetic field. The magnetic fluid bridge is formed in the space between a pair of identical coaxial cylindrical permanent magnets submerged in water. The direction of alternating magnetic field is parallel /antiparallel to the magnetic field produced by two permanent magnets. The magnetic fluid bridge responds to the external alternating magnetic field with harmonic oscillation. The oscillation of magnetic fluid bridge generates water flow around the bridge. Water flow is visualized using a thin milk film at the container bottom. Water flows are observed with a high-speed video camera analysis system. The experimental results show that the flow pattern induced by the bridge oscillation depends on the Keulegan–Carpenter number.

  12. Water flow patterns induced by bridge oscillation of magnetic fluid between two permanent magnets subjected to alternating magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Sudo, Seiichi, E-mail: sudo@akita-pu.ac.jp [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Yamamoto, Kazuki [Graduate School of Engineering, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Ishimoto, Yukitaka; Nix, Stephanie [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan)

    2017-06-01

    This paper describes the characteristics of water flow induced by the bridge oscillation of magnetic fluid between two permanent magnets subject to an external alternating magnetic field. The magnetic fluid bridge is formed in the space between a pair of identical coaxial cylindrical permanent magnets submerged in water. The direction of alternating magnetic field is parallel /antiparallel to the magnetic field produced by two permanent magnets. The magnetic fluid bridge responds to the external alternating magnetic field with harmonic oscillation. The oscillation of magnetic fluid bridge generates water flow around the bridge. Water flow is visualized using a thin milk film at the container bottom. Water flows are observed with a high-speed video camera analysis system. The experimental results show that the flow pattern induced by the bridge oscillation depends on the Keulegan–Carpenter number.

  13. Modeling forces in high-temperature superconductors

    International Nuclear Information System (INIS)

    Turner, L. R.; Foster, M. W.

    1997-01-01

    We have developed a simple model that uses computed shielding currents to determine the forces acting on a high-temperature superconductor (HTS). The model has been applied to measurements of the force between HTS and permanent magnets (PM). Results show the expected hysteretic variation of force as the HTS moves first toward and then away from a permanent magnet, including the reversal of the sign of the force. Optimization of the shielding currents is carried out through a simulated annealing algorithm in a C++ program that repeatedly calls a commercial electromagnetic software code. Agreement with measured forces is encouraging

  14. Permanent magnet machine with windings having strand transposition

    Science.gov (United States)

    Qu, Ronghai; Jansen, Patrick Lee

    2009-04-21

    This document discusses, among other things, a stator with transposition between the windings or coils. The coils are free from transposition to increase the fill factor of the stator slots. The transposition at the end connections between an inner coil and an outer coil provide transposition to reduce circulating current loss. The increased fill factor reduces further current losses. Such a stator is used in a dual rotor, permanent magnet machine, for example, in a compressor pump, wind turbine gearbox, wind turbine rotor.

  15. 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....

  16. Dynamics and Stability of Permanent-Magnet Synchronous Motor

    OpenAIRE

    He, Ren; Han, Qingzhen

    2017-01-01

    The aim of this article is to explore the dynamic characteristics and stability of the permanent-magnet synchronous motor (PMSM). PMSM equilibrium local stability condition and Hopf  bifurcation condition, pitchfork bifurcation condition, and fold bifurcation condition have been derived by using the Routh-Hurwitz criterion and the bifurcation theory, respectively. Bifurcation curves of the equilibrium with single and double parameters are obtained by continuation method. Numerical simulations...

  17. Forces between a permanent magnet and a soft magnetic plate

    Czech Academy of Sciences Publication Activity Database

    Beleggia, M.; Vokoun, David; DeGraef, M.

    2012-01-01

    Roč. 3, č. 5 (2012), 0500204/1-0500204/4 ISSN 1949-307X R&D Projects: GA ČR GPP108/12/P111 Institutional research plan: CEZ:AV0Z10100520 Keywords : electromagnetics * hard magnetic materials * soft magnetic materials Subject RIV: BM - Solid Matter Physics ; Magnetism http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6313974

  18. 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...

  19. 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.

  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. Permanent magnet design for magnetic heat pumps using total cost minimization

    Science.gov (United States)

    Teyber, R.; Trevizoli, P. V.; Christiaanse, T. V.; Govindappa, P.; Niknia, I.; Rowe, A.

    2017-11-01

    The active magnetic regenerator (AMR) is an attractive technology for efficient heat pumps and cooling systems. The costs associated with a permanent magnet for near room temperature applications are a central issue which must be solved for broad market implementation. To address this problem, we present a permanent magnet topology optimization to minimize the total cost of cooling using a thermoeconomic cost-rate balance coupled with an AMR model. A genetic algorithm identifies cost-minimizing magnet topologies. For a fixed temperature span of 15 K and 4.2 kg of gadolinium, the optimal magnet configuration provides 3.3 kW of cooling power with a second law efficiency (ηII) of 0.33 using 16.3 kg of permanent magnet material.

  2. 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.

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

    International Nuclear Information System (INIS)

    Sivaprasad, K.; Ganesh Sundara Raman, S.; Mastanaiah, P.; Madhusudhan Reddy, G.

    2006-01-01

    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 δ needles

  4. Temperature compensation of NdFeB permanent magnets

    International Nuclear Information System (INIS)

    Kim, S.H.; Doose, C.

    1997-01-01

    Permanent magnet blocks of NdFeB have a relatively high maximum energy product. Because of its relatively low Curie temperature, however, NdFeB has a large temperature coefficient for its residual induction. The temperature coefficients of the relative magnetic fields (ΔB/B)/ΔT in the air gap of NdFeB dipole magnets were reduced from -1.1 x 10 -3 /c to less than 2 x 10 -5 /degree C under operating temperatures of ± 6 C. This was achieved passively by using 1.25-mm-thick strips of 30%-Ni-Fe alloy as flux shunts for the NdFeB blocks. The magnets with soft-steel poles and flux-return yokes were assembled and measured in a temperature-controlled environment

  5. 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.

  6. Addressing Criticality in Rare Earth Elements via Permanent Magnets Recycling

    Science.gov (United States)

    Nlebedim, I. C.; King, A. H.

    2018-02-01

    Rare earth elements (REEs) are critical for many advanced technologies and are faced with potential supply disruptions. Recycling of permanent magnets (PMs) can be good sources for REEs which can help minimize global dependence on freshly mined REEs, but PMs are rarely recycled. Recycling of PMs has been discussed with respect to improving REEs resource sustainability. Some challenges to be addressed in order to establish industrially deployable technologies for PMs recycling have also been discussed, including profitability, energy efficiency and environmental impacts. Key considerations for promoting circular economy via PMs recycling is proposed with the focus on deciding the target points in the supply chain at which the recycled products will be inserted. Important technical considerations for recycling different forms of waste PMs, including swarfs, slags, shredded and intact hard disk drives magnets, have been presented. The aspects of circular economy considered include reusing magnets, remanufacturing magnets and recovering of REEs from waste PMs.

  7. Development of a cryogenic permanent magnet undulator at the ESRF

    International Nuclear Information System (INIS)

    Kitegi, Ch.

    2008-12-01

    In 2004, at SPring-8, Toru Hara proposed a new concept of undulator with a short period and a high field: the Cryogenic Permanent Magnet Undulator (CPMU). The purpose of this concept is to cool Nd 2 Fe 14 B magnets at 150 K. This cooling allows magnets which have a higher remanence to be used, up to 40% higher than that of the magnets traditionally used in undulators. In order to assess the technological possibility of producing such undulator, a 2 m long undulator with a 18 mm period has been proposed at the ESRF. This piece of work presents the design and the construction of this CPMU at the ESRF. First a magnetic model of the CPMU is introduced; it is based on measurements of the magnetization curve at cryogenic temperature performed at the Louis Neel Laboratory. This model forecasts an increase of the peak field of 8% and of the field integral of 0.2 Gm at around 150 K. A unique magnetic measurement bench has been developed at the ESRF. This bench allows both the in vacuum local field and field integral to be measured. Its design and construction are presented. Finally we have reviewed the measurements at room and cryogenic temperature. These measurements are in agreement with the magnetic model. (author)

  8. Permanent magnetic lattices for ultracold atoms and quantum degenerate gases

    International Nuclear Information System (INIS)

    Ghanbari, Saeed; Kieu, Tien D; Sidorov, Andrei; Hannaford, Peter

    2006-01-01

    We propose the use of periodic arrays of permanent magnetic films for producing magnetic lattices of microtraps for confining, manipulating and controlling small clouds of ultracold atoms and quantum degenerate gases. Using analytical expressions and numerical calculations we show that periodic arrays of magnetic films can produce one-dimensional (1D) and two-dimensional (2D) magnetic lattices with non-zero potential minima, allowing ultracold atoms to be trapped without losses due to spin flips. In particular, we show that two crossed layers of periodic arrays of parallel rectangular magnets plus bias fields, or a single layer of periodic arrays of square-shaped magnets with three different thicknesses plus bias fields, can produce 2D magnetic lattices of microtraps having non-zero potential minima and controllable trap depth. For arrays with micron-scale periodicity, the magnetic microtraps can have very large trap depths (∼0.5 mK for the realistic parameters chosen for the 2D lattice) and very tight confinement

  9. Critical current measurements of high-temperature superconducting short samples at a wide range of temperatures and magnetic fields

    Science.gov (United States)

    Ma, Hongjun; Liu, Huajun; Liu, Fang; Zhang, Huahui; Ci, Lu; Shi, Yi; Lei, Lei

    2018-01-01

    High-Temperature Superconductors (HTS) are potential materials for high-field magnets, low-loss transmission cables, and Superconducting Magnetic Energy Storage (SMES) due to their high upper critical magnetic field (Hc2) and critical temperature (Tc). The critical current (Ic) of HTS, which is one of the most important parameters for superconductor application, depends strongly on the magnetic fields and temperatures. A new Ic measurement system that can carry out accurate Ic measurement for HTS short samples with various temperatures (4.2-80 K), magnetic fields (0-14 T), and angles of the magnetic field (0°-90°) has been developed. The Ic measurement system mainly consists of a measurement holder, temperature-control system, background magnet, test cryostat, data acquisition system, and DC power supply. The accuracy of temperature control is better than ±0.1 K over the 20-80 K range and ±0.05 K when measured below 20 K. The maximum current is over 1000 A with a measurement uncertainty of 1%. The system had been successfully used for YBa2Cu3O7-x(YBCO) tapes Ic determination with different temperatures and magnetic fields.

  10. Critical current measurements of high-temperature superconducting short samples at a wide range of temperatures and magnetic fields.

    Science.gov (United States)

    Ma, Hongjun; Liu, Huajun; Liu, Fang; Zhang, Huahui; Ci, Lu; Shi, Yi; Lei, Lei

    2018-01-01

    High-Temperature Superconductors (HTS) are potential materials for high-field magnets, low-loss transmission cables, and Superconducting Magnetic Energy Storage (SMES) due to their high upper critical magnetic field (H c2 ) and critical temperature (T c ). The critical current (I c ) of HTS, which is one of the most important parameters for superconductor application, depends strongly on the magnetic fields and temperatures. A new I c measurement system that can carry out accurate I c measurement for HTS short samples with various temperatures (4.2-80 K), magnetic fields (0-14 T), and angles of the magnetic field (0°-90°) has been developed. The I c measurement system mainly consists of a measurement holder, temperature-control system, background magnet, test cryostat, data acquisition system, and DC power supply. The accuracy of temperature control is better than ±0.1 K over the 20-80 K range and ±0.05 K when measured below 20 K. The maximum current is over 1000 A with a measurement uncertainty of 1%. The system had been successfully used for YBa 2 Cu 3 O 7-x (YBCO) tapes I c determination with different temperatures and magnetic fields.

  11. Quench detection for high temperature superconductor magnets: a novel technique based on Rayleigh-backscattering interrogated optical fibers

    International Nuclear Information System (INIS)

    Scurti, F; Ishmael, S; Schwartz, J; Flanagan, G

    2016-01-01

    High temperature superconducting materials are the only option for the generation of magnetic fields exceeding 25 T and for magnets operating over a broad range of temperature and magnetic field for power applications. One remaining obstacle for the implementation of high temperature superconductors magnets into systems, however, is the inability to rapidly detect a quench. In this letter we present a novel quench detection technique that has been investigated experimentally. Optical fibers are co-wound into two small Bi 2 Sr 2 Ca 2 Cu 3 O 10+x superconducting coils and interrogated by Rayleigh-backscattering. Two different configurations are used, one with the fiber atop the conductor and the other with the fiber located as turn-to-turn insulation. Each coil is also instrumented with voltage taps (VTs) and thermocouples for comparison during heater-induced quenches. The results show that Rayleigh-backscattering interrogated optical fibers (RIOF) have significant advantages over traditional techniques, including very high spatial resolution and the ability to detect a hot-spot well before the peak local temperature exceeds the current sharing temperature. Thus, RIOF quench detection is intrinsically faster than VTs, and this intrinsic advantage is greater as the coil size and/or current margin increases. (letter)

  12. Topology optimization for design of segmented permanent magnet arrays with ferromagnetic materials

    Science.gov (United States)

    Lee, Jaewook; Yoon, Minho; Nomura, Tsuyoshi; Dede, Ercan M.

    2018-03-01

    This paper presents multi-material topology optimization for the co-design of permanent magnet segments and iron material. Specifically, a co-design methodology is proposed to find an optimal border of permanent magnet segments, a pattern of magnetization directions, and an iron shape. A material interpolation scheme is proposed for material property representation among air, permanent magnet, and iron materials. In this scheme, the permanent magnet strength and permeability are controlled by density design variables, and permanent magnet magnetization directions are controlled by angle design variables. In addition, a scheme to penalize intermediate magnetization direction is proposed to achieve segmented permanent magnet arrays with discrete magnetization directions. In this scheme, permanent magnet strength is controlled depending on magnetization direction, and consequently the final permanent magnet design converges into permanent magnet segments having target discrete directions. To validate the effectiveness of the proposed approach, three design examples are provided. The examples include the design of a dipole Halbach cylinder, magnetic system with arbitrarily-shaped cavity, and multi-objective problem resembling a magnetic refrigeration device.

  13. Optimization of permanent-magnet undulator magnets ordering using simulated annealing algorithm

    International Nuclear Information System (INIS)

    Chen Nian; He Duohui; Li Ge; Jia Qika; Zhang Pengfei; Xu Hongliang; Cai Genwang

    2005-01-01

    Pure permanent-magnet undulator consists of many magnets. The unavoidable remanence divergence of these magnets causes the undulator magnetic field error, which will affect the functional mode of the storage ring and the quality of the spontaneous emission spectrum. Optimizing permanent-magnet undulator magnets ordering using simulated annealing algorithm before installing undulator magnets, the first field integral can be reduced to 10 -6 T·m, the second integral to 10 -6 T·m 2 and the peak field error to less than 10 -4 . The optimized results are independent of the initial solution. This paper gives the optimizing process in detail and puts forward a method to quickly calculate the peak field error and field integral according to the magnet remanence. (authors)

  14. Numerical simulation of permanent magnet method: Influence of experimental conditions on accuracy of j{sub C}-distribution

    Energy Technology Data Exchange (ETDEWEB)

    Takayama, T., E-mail: takayama@yz.yamagata-u.ac.j [Faculty of Engineering, Yamagata University, 4-3-16, Johnan, Yonezawa, Yamagata 992-8510 (Japan); Kamitani, A.; Tanaka, A. [Graduate School of Science and Engineering, Yamagata University, 4-3-16, Johnan, Yonezawa, Yamagata 992-8510 (Japan)

    2010-11-01

    Influence of the magnet position on the determination of the distribution of the critical current density in a high-temperature superconducting (HTS) thin film has been investigated numerically. For this purpose, a numerical code has been developed for analyzing the shielding current density in a HTS sample. By using the code, the permanent magnet method is reproduced. The results of computations show that, even if the center of the permanent magnet is located near the film edge, the maximum repulsive force is roughly proportional to the critical current density. This means that the distribution of the critical current density in the HTS film can be estimated from the proportionality constants determined by using the relations between the maximum repulsive force and the critical current density.

  15. Formation of compact toroidal configurations for magnetic confinement of high temperature plasmas

    International Nuclear Information System (INIS)

    Fuentes, N.O.; Rodrigo, A.B.

    1986-01-01

    The formation stage of inverted magnetic field toroidal configurations (FRC) for hot plasmas confinement using a low energy linear theta pinch is studied. The diagnostic techniques used are based on optical spectroscopy, ultrarapid photography, magnetic probes and excluded flux compensated bonds. The generalities of the present research program, the used diagnostic techniques and the results obtained are discussed. (Author)

  16. Repulsion analysis of permanent magnets for the Hoop energy storage system

    International Nuclear Information System (INIS)

    O, B. H.; Cho, S. B.; Kim, D. I.

    1996-01-01

    The repulsion force of permanent magnets is studied in order to analyze the instability problem of the rotational motion of a hoop levitated by permanent magnets in the Hoop Energy Storage System (HESS). The hoop of permanent magnets is levitated to remove the mechanical complexities caused by the rotational axis. It is important to maintain stable rotational motion at any speed for the efficiency as well as the safety of the system. To set up the equations of motion, the force of levitation and the source of perturbation are represented in terms of real parameters of the permanent magnets. The instability conditions and various geometric effects of the permanent magnets are analyzed. (author)

  17. Magnetic levitation force between a superconducting bulk magnet and a permanent magnet

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J J; He, C Y; Meng, L F; Li, C; Han, R S; Gao, Z X [Department of Physics, Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Peking University, Beijing 100871 (China)

    2003-04-01

    The current density J({rho}, z) in a disc-shaped superconducting bulk magnet and the magnetic levitation force F{sup SBM}{sub z} exerted on the superconducting bulk magnet by a cylindrical permanent magnet are calculated from first principles. The effect of the superconducting parameters of the superconducting bulk is taken into account by assuming the voltage-current law E = E{sub c}(J/J{sub c}){sup n} and the material law B = {mu}{sub 0}H. The magnetic levitation force F{sup SBM}{sub z} is dominated by the remnant current density J'{sub 2}({rho}, z), which is induced by switching off the applied magnetizing field. High critical current density and flux creep exponent may increase the magnetic levitation force F{sup SBM}{sub z}. Large volume and high aspect ratio of the superconducting bulk can further enhance the magnetic levitation force F{sup SBM}{sub z}.

  18. A combination of permanent magnet and magnetic coil for a large diameter ion source

    International Nuclear Information System (INIS)

    Uramoto, Joshin; Kubota, Yusuke; Miyahara, Akira.

    1980-02-01

    A large diameter ion source for fast neutral beam injection is designed under a magnetic field (we call ''Uramoto Field'') composed of a circular ferrite permanent magnet and a usual coreless magnetic coil. As the magnetic filed is reduced abruptly in a discharge anode, an ion source with a uniform ion current density over a large diameter is produced easily without a ''button'' of ORNL duoPIGatron type ion source (a floating electrode to diffuse an axial plasma flow radially). (author)

  19. 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.

  20. New developments in NdFeB-based permanent magnets

    International Nuclear Information System (INIS)

    Liu, Z.W.

    2011-01-01

    NdFeB based alloys have been used as permanent magnets for almost thirty years. The recent researches aim at optimizing the composition, microstructure and properties, reducing cost, and developing new processes. The demand for sintered magnet is increasing. Efforts are directed towards improving properties by controlling grain boundary diffusion, minimizing the rare earth (RE) content and also improving production yield. As for bonded magnets, to enhance remanence and energy product, nanocrystalline powders are employed. High thermal stability has been realized by mixing NdFeB with hard ferrite powders. For nanocrystalline and nano composite NdFeB based alloys, both compositional modification and microstructural optimization have been carried out. New approaches have also been proposed to prepare NdFeB magnets with idea structure. Surfactant assisted ball milling is a good top-down method to obtain nano sized hard magnetic particles and anisotropic nano flakes. Synthesis of NdFeB nanoparticles and NdFeB/Fe (Co) nano composite powders by bottom-up techniques, such as chemical reduction process and co-precipitation, has been successful very recently. To assemble nanocrystalline NdFeB powders or nanoparticles into bulk magnets, various novel consolidation processes including spark plasma sintering and high velocity press have been employed. Hot deformation can be selected as the process to achieve anisotropy in nanocrystalline magnets. (author)

  1. Highly stable and finely tuned magnetic fields generated by permanent magnet assemblies.

    Science.gov (United States)

    Danieli, E; Perlo, J; Blümich, B; Casanova, F

    2013-05-03

    Permanent magnetic materials are the only magnetic source that can be used to generate magnetic fields without power consumption or maintenance. Such stand-alone magnets are very attractive for many scientific and engineering areas, but they suffer from poor temporal field stability, which arises from the strong sensitivity of the magnetic materials and mechanical support to temperature variation. In this work, we describe a highly efficient method useful to cancel the temperature coefficient of permanent magnet assemblies in a passive and accurate way. It is based on the combination of at least two units made of magnetic materials with different temperature coefficients arranged in such a way that the ratio of the fields generated by each unit matches the ratio of their effective temperature coefficients defined by both the magnetic and mechanical contributions. Although typically available magnetic materials have negative temperature coefficients, the cancellation is achieved by aligning the fields generated by each unit in the opposite direction. We demonstrate the performance of this approach by stabilizing the field generated by a dipolar Halbach magnet, recently proposed to achieve high field homogeneity. Both the field drift and the homogeneity are monitored via nuclear magnetic resonance spectroscopy experiments. The results demonstrate the compatibility of the thermal compensation approach with existing strategies useful to fine-tune the spatial dependence of the field generated by permanent magnet arrays.

  2. [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.

  3. 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.

  4. 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.

  5. A novel permanent maglev rotary LVAD with passive magnetic bearings.

    Science.gov (United States)

    Qian, K X; Yuan, H Y; Zeng, P; Ru, W M

    2005-01-01

    It has been widely acknowledged that permanent maglev cannot achieve stability; however, the authors have discovered that stable permanent maglev is possible under the effect of a combination of passive magnetic and nonmagnetic forces. In addition, a rotary left ventricular assist device (LVAD) with passive magnetic bearings has been developed. It is a radially driven impeller pump, having a rotor and a stator. The rotor consists of driven magnets and impeller; the motor coil and pump housing form the stator. Two passive magnetic bearings counteract the attractive force between motor coil iron core and rotor magnets; the rotor thereafter can be disaffiliated from the stator and become levitated under the action of passive magnetic and haemodynamic forces. Because of the pressure difference between the outlet and the inlet of the pump, there is a small flow passing through the gap of rotor and stator, and then entering the lower pressure area along the central hole of the rotor. This small flow comes to a full washout of all blood contacting surfaces in the motor. Moreover, a decreased Bernoulli force in the larger gap with faster flow produces a centring force that leads to stable levitation of the rotor. Resultantly, neither mechanical wear nor thrombosis will occur in the pump. The rotor position detection reveals that the precondition of levitation is a high rotating speed (over 3250 rpm) and a high flow rate (over 1 l min(-1)). Haemodynamic tests with porcine blood indicate that the device as a LVAD requires a rotating speed between 3500 and 4000 rpm for producing a blood flow of 4 - 6 l min(-1) against 100 mmHg mean pressure head. The egg-sized device has a weight of 200 g and an O.D. of 40 mm at its largest point.

  6. Ultra-High Field Magnets for X-Ray and Neutron Scattering using High Temperature Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Winn, Barry L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Broholm, C. [Johns Hopkins Univ., Baltimore, MD (United States); Bird, M. [Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab); Breneman, Bruce C. [General Atomics, San Diego, CA (United States); Coffey, Michael [Cryomagnetics, Oak Ridge, TN (United States); Cutler, Roy I. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Duckworth, Robert C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Erwin, R. [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Hahn, Seungyong [Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab); Hernandez, Yamali [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Herwig, Kenneth W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Holland, Leo D. [General Atomics, San Diego, CA (United States); Lonergan, Kevin M. [Oxford Instruments, Abingdon (United Kingdom); Melhem, Ziad [Oxford Instruments, Abingdon (United Kingdom); Minter, Stephen J. [Cryomagnetics, Oak Ridge, TN (United States); Nelson, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Paranthaman, M. Parans [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pierce, Josh [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ruff, Jacob [Cornell Univ., Ithaca, NY (United States); Shen, Tengming [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sherline, Todd E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Smeibidl, Peter G. [Helmholtz-Zentrum Berlin (HZB), (Germany); Tennant, David [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); van der Laan, Danko [Advanced Conductor Technologies, LLC, Boulder, CO (United States); Wahle, Robert J. [Helmholtz-Zentrum Berlin (HZB), (Germany); Zhang, Yifei [SuperPower, Inc., Schenectady, NY (United States)

    2017-01-01

    X-ray and neutron scattering techniques are capable of acquiring information about the structure and dynamics of quantum matter. However, the high-field magnet systems currently available at x-ray and neutron scattering facilities in the United States are limited to fields of 16 tesla (T) at maximum, which precludes applications that require and/or study ultra-high field states of matter. This gap in capability—and the need to address it—is a central conclusion of the 2005 National Academy of Sciences report by the Committee on Opportunities in High Magnetic Field Science. To address this gap, we propose a magnet development program that would more than double the field range accessible to scattering experiments. With the development and use of new ultra-high field–magnets, the program would bring into view new worlds of quantum matter with profound impacts on our understanding of advanced electronic materials.

  7. Highly temperature responsive core-shell magnetic particles: synthesis, characterization and colloidal properties.

    Science.gov (United States)

    Rahman, Md Mahbubor; Chehimi, Mohamed M; Fessi, Hatem; Elaissari, Abdelhamid

    2011-08-15

    Temperature responsive magnetic polymer submicron particles were prepared by two step seed emulsion polymerization process. First, magnetic seed polymer particles were obtained by emulsion polymerization of styrene using potassium persulfate (KPS) as an initiator and divinylbenzne (DVB) as a cross-linker in the presence of oil-in-water magnetic emulsion (organic ferrofluid droplets). Thereafter, DVB cross-linked magnetic polymer particles were used as seed in the precipitation polymerization of N-isopropylacrylamide (NIPAM) to induce thermosensitive PNIPAM shell onto the hydrophobic polymer surface of the cross-linked magnetic polymer particles. To impart cationic functional groups in the thermosensitive PNIPAM backbone, the functional monomer aminoethylmethacrylate hydrochloride (AEMH) was used to polymerize with NIPAM while N,N'-methylenebisacrylamide (MBA) and 2, 2'-azobis (2-methylpropionamidine) dihydrochloride (V-50) were used as a cross-linker and as an initiator respectively. The effect of seed to monomer (w/w) ratio along with seed nature on the final particle morphology was investigated. Dynamic light scattering (DLS) results demonstrated particles swelling at below volume phase transition temperature (VPTT) and deswelling above the VPTT. The perfect core (magnetic) shell (polymer) structure of the particles prepared was confirmed by Transmission Electron Microscopy (TEM). The chemical composition of the particles were determined by thermogravimetric analysis (TGA). The effect of temperature, pH, ionic strength on the colloidal properties such as size and zeta potential of the micron sized thermo-sensitive magnetic particles were also studied. In addition, a short mechanistic discussion on the formation of core-shell morphology of magnetic polymer particles has also been discussed. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. Influence of coating on nanocrystalline magnetic properties during high temperature thermal ageing

    Energy Technology Data Exchange (ETDEWEB)

    Lekdim, Atef, E-mail: atef.lekdim@univ-lyon1.fr; Morel, Laurent; Raulet, Marie-Ange

    2017-05-15

    Since their birth or mergence the late 1980s, the nanocrystalline ultrasoft magnetic materials are taking a great importance in power electronic systems conception. One of the main advantages that make them more attractive nowadays is their ability to be packaged since the reduction of the magnetostrictive constant to almost zero. In aircraft applications, due to the high component compactness and to their location (for example near the jet engine), the operating temperature increases and may reach easily 200 °C and more. Consequently, the magnetic thermal ageing may occur but is, unfortunately, weakly studied. This paper focuses on the influence of the coating (packaging type) on the magnetic nanocrystalline performances during a thermal ageing. This study is based on monitoring the magnetic characteristics of two types of nanocrystalline cores (naked and coated) during a thermal activated ageing (100, 150 and 200 °C). Based on a dedicated monitoring protocol, a large magnetic characterization has been done and analyzed. Elsewhere, X-Ray Diffraction and magnetostriction measurements were carried out to support the study of the anisotropy energies evolution with ageing. This latter is discussed in this paper to explain and give hypothesis about the ageing phenomena. - Highlights: • The coating impacts drastically the magnetic properties during thermal ageing. • Irreversible ageing phenomena after the total coating breakage. • The deteriorations are related to the storage of the magnetoelastic anisotropy.

  9. 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).

  10. On a neutral particle with permanent magnetic dipole moment in a magnetic medium

    Science.gov (United States)

    Bakke, K.; Salvador, C.

    2018-03-01

    We investigate quantum effects that stem from the interaction of a permanent magnetic dipole moment of a neutral particle with an electric field in a magnetic medium. We consider a long non-conductor cylinder that possesses a uniform distribution of electric charges and a non-uniform magnetization. We discuss the possibility of achieving this non-uniform magnetization from the experimental point of view. Besides, due to this non-uniform magnetization, the permanent magnetic dipole moment of the neutral particle also interacts with a non-uniform magnetic field. This interaction gives rise to a linear scalar potential. Then, we show that bound states solutions to the Schrödinger-Pauli equation can be achieved.

  11. Post-assembly magnetization of a 100 kW high speed permanent magnet rotor.

    Science.gov (United States)

    Lv, Yiliang; Wang, Guobin; Li, Liang

    2015-03-01

    A post-assembly magnetizing fixture has been designed and successfully used to magnetize the rotor of a 100 kW high speed permanent magnet synchronous motor. The rotor is a solid cylinder with outer diameter of 80 mm and total length of 515 mm. The permanent magnet material is samarium-cobalt (Sm2Co17) with saturation magnetizing field of 6 T. The mechanical stability of the magnetizing fixture has been studied as well as the general design methodology. The magnetizing coil is subdivided in order to reduce the electromagnetic force, and the coils are separately reinforced in different ways. The electromagnetic and structural optimization is performed by finite element analysis and verified by experiments.

  12. Post-assembly magnetization of a 100 kW high speed permanent magnet rotor

    International Nuclear Information System (INIS)

    Lv, Yiliang; Wang, Guobin; Li, Liang

    2015-01-01

    A post-assembly magnetizing fixture has been designed and successfully used to magnetize the rotor of a 100 kW high speed permanent magnet synchronous motor. The rotor is a solid cylinder with outer diameter of 80 mm and total length of 515 mm. The permanent magnet material is samarium-cobalt (Sm 2 Co 17 ) with saturation magnetizing field of 6 T. The mechanical stability of the magnetizing fixture has been studied as well as the general design methodology. The magnetizing coil is subdivided in order to reduce the electromagnetic force, and the coils are separately reinforced in different ways. The electromagnetic and structural optimization is performed by finite element analysis and verified by experiments

  13. Post-assembly magnetization of a 100 kW high speed permanent magnet rotor

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Yiliang; Wang, Guobin [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan (China); Li, Liang [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan (China); State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan (China)

    2015-03-15

    A post-assembly magnetizing fixture has been designed and successfully used to magnetize the rotor of a 100 kW high speed permanent magnet synchronous motor. The rotor is a solid cylinder with outer diameter of 80 mm and total length of 515 mm. The permanent magnet material is samarium-cobalt (Sm{sub 2}Co{sub 17}) with saturation magnetizing field of 6 T. The mechanical stability of the magnetizing fixture has been studied as well as the general design methodology. The magnetizing coil is subdivided in order to reduce the electromagnetic force, and the coils are separately reinforced in different ways. The electromagnetic and structural optimization is performed by finite element analysis and verified by experiments.

  14. 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.

  15. 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.

  16. A novel structure of permanent-magnet-biased radial hybrid magnetic bearing

    International Nuclear Information System (INIS)

    Sun Jinji; Fang Jiancheng

    2011-01-01

    The paper proposes a novel structure for a permanent-magnet-biased radial hybrid magnetic bearing. Based on the air gap between the rotor and stator of traditional radial hybrid magnetic bearings, a subsidiary air gap is first constructed between the permanent magnets and the inner magnetic parts. Radial magnetic bearing makes X and Y magnetic fields independent of each other with separate stator poles, and the subsidiary air gap makes control flux to a close loop. As a result, magnetic field coupling of the X and Y channels is decreased significantly by the radial hybrid magnetic bearing and makes it easier to design control systems. Then an external rotor structure is designed into the radial hybrid magnetic bearing. The working principle of the radial hybrid magnetic bearing and its mathematical model is discussed. Finally, a non-linear magnetic network method is proposed to analyze the radial hybrid magnetic bearing. Simulation results indicate that magnetic fields in the two channels of the proposed radial hybrid magnetic bearing decouple well from each other.

  17. A novel structure of permanent-magnet-biased radial hybrid magnetic bearing

    Energy Technology Data Exchange (ETDEWEB)

    Sun Jinji, E-mail: sunjinji@aspe.buaa.edu.c [Key Laboratory of Fundamental Science for National Defense, Novel Inertial Instrument and Navigation System Technology, School of Instrument Science and Opto-electronics Engineering, Beijing University of Aeronautics and Astronautics, 100191 (China); Fang Jiancheng [Key Laboratory of Fundamental Science for National Defense, Novel Inertial Instrument and Navigation System Technology, School of Instrument Science and Opto-electronics Engineering, Beijing University of Aeronautics and Astronautics, 100191 (China)

    2011-01-15

    The paper proposes a novel structure for a permanent-magnet-biased radial hybrid magnetic bearing. Based on the air gap between the rotor and stator of traditional radial hybrid magnetic bearings, a subsidiary air gap is first constructed between the permanent magnets and the inner magnetic parts. Radial magnetic bearing makes X and Y magnetic fields independent of each other with separate stator poles, and the subsidiary air gap makes control flux to a close loop. As a result, magnetic field coupling of the X and Y channels is decreased significantly by the radial hybrid magnetic bearing and makes it easier to design control systems. Then an external rotor structure is designed into the radial hybrid magnetic bearing. The working principle of the radial hybrid magnetic bearing and its mathematical model is discussed. Finally, a non-linear magnetic network method is proposed to analyze the radial hybrid magnetic bearing. Simulation results indicate that magnetic fields in the two channels of the proposed radial hybrid magnetic bearing decouple well from each other.

  18. A Review of Permanent Magnet Stirring During Metal Solidification

    Science.gov (United States)

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

    2017-12-01

    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.

  19. Analysis of an adjustable field permanent magnet solenoid

    Science.gov (United States)

    Burris-Mog, T.; Burns, M.; Chavez, A.; Schillig, J.

    2017-10-01

    A feasibility study has been performed on an adjustable-field permanent magnet (PM) solenoid concept in an effort to reduce the dependence that linear induction accelerators have on large direct current power supplies and associated cooling systems. The concept relies on the ability to reorient sections of the PMs and thus redirect their magnetization vector to either add to or subtract from the on-axis magnetic field. This study concentrated on the focal strengths and emittance growths for two different designs, both with 19 cm bore diameters extending 53 cm in length. The first design is expected to produce peak magnetic fields ranging from 260 to 900 G (0.026 to 0.09 T) while the second design is expected to produce peak magnetic fields ranging from 580 to 2100 G (0.058 to 0.21 T). Although the PM configuration generates a variable magnetic field and the torques acting on PMs within the assembly appear manageable, the emittance growth is larger than that of a DC solenoid.

  20. 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.

  1. Permanent magnetic ferrite based power-tunable metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guanqiao; Lan, Chuwen [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Gao, Rui [High Temperature Thermochemistry Laboratory, Department of Mining and Materials Engineering, McGill University, Montreal, Quebec H3A 0C5 (Canada); Zhou, Ji, E-mail: zhouji@tsinghua.edu.cn [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2017-08-15

    Highlights: • Power-tunable metamaterials based on barium permanent magnetic ferrite have been proposed and fabricated. • It is observed that resonant frequency of the array shifts upon altering the output power. • This kind of power-tunable behavior is due to the temperature rise as a result of FMR-induced heat buildup. • This work offers a practical idea to tune ferrite metamaterials besides magneto-tunability and thermal-tunability. - Abstract: 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.

  2. 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. Susp...

  3. Improvement of permanent magnet machines performance by including magnetic shells into the rotor geometry

    International Nuclear Information System (INIS)

    Alnaemi, F.; Moses, A.J.

    2003-01-01

    FEM modelling of PM motor was carried out to demonstrate the effects of the addition of various types of ferromagnetic tubes (shell) to a rotor of surface mount permanent magnet motor. An enhancement in magnet operating point towards the high field region is obtained. A shell made of amorphous ribbon offers optimum advantages

  4. 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...

  5. Low temperature X-ray imaging of magnetic flux patterns in high temperature superconductors

    Science.gov (United States)

    Stahl, Claudia; Ruoß, Stephen; Weigand, Markus; Bechtel, Michael; Schütz, Gisela; Albrecht, Joachim

    2015-05-01

    We present X-ray magnetic circular dichroism (XMCD) microscopy results obtained at liquid nitrogen temperatures on the high-Tc superconductor YBCO (YBa2Cu3O7-δ). The magnetic flux distribution arising from electric currents in the superconductor is detected and visualized using soft-magnetic Co40Fe40B20 (CoFeB) as sensor layer and XMCD as contrast mechanism. It has been shown that the XMCD contrast in the sensor layer directly corresponds to magnetic flux distribution of the superconductor and hence can be used to image magnetic structures in superconductors [Stahl et al., Phys. Rev. B 90, 104515 (2014)]. The existing scanning UHV X-ray microscopy setup MAXYMUS at the synchrotron BESSY II in Berlin has been upgraded for that purpose: we use a nitrogen based MMR Micro Miniature Joule-Thompson Cryostat with temperature range from 75 K to 580 K. The capability of the method is demonstrated on two different superconducting samples, an optimally doped thin film and a melt-textured block.

  6. Magnetization hysteresis and history effects in conventional and high temperature superconductors

    International Nuclear Information System (INIS)

    Chaddah, P.

    1990-01-01

    The magnetization in hard superconductors is irreversible and history-dependent, and cannot be a priori compared with the equilibrium magnetization. These features have gained prominence in the high T c superconductors (HTSC) where the short coherence length presumably leads to intrinsic pinning. Various experimental features, first noticed in the HTSC, are explained by an extension of Bean's macroscopic model to include temperature variations and the field dependence of J c . This paper discusses recent measurements of history effects in niobium and show their similarities with other published data on HTSC. The authors also present our calculations of magnetization behaviour in hard superconductors of sample-shapes having a non-zero demagnetization factor

  7. 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 background for the specifications are elaborated. Simulated as well as measured results of rotational losses of the first and second version are compared. The efficiency of the new design is investigated and compared to three direct drive motors in a few operating points and the MIPMG v.2 seems superior when...

  8. Impulsive control of permanent magnet synchronous motors with parameters uncertainties

    International Nuclear Information System (INIS)

    Li Dong; Zhang Xiaohong; Wang Shilong; Yan Dan; Wang Hui

    2008-01-01

    The permanent magnet synchronous motors (PMSMs) may have chaotic behaviours for the uncertain values of parameters or under certain working conditions, which threatens the secure and stable operation of motor-driven. It is important to study methods of controlling or suppressing chaos in PMSMs. In this paper, robust stabilities of PMSM with parameter uncertainties are investigated. After the uncertain matrices which represent the variable system parameters are formulated through matrix analysis, a novel asymptotical stability criterion is established. Some illustrated examples are also given to show the effectiveness of the obtained results

  9. Nonlinear chaos control in a permanent magnet reluctance machine

    International Nuclear Information System (INIS)

    Harb, Ahmad M.

    2004-01-01

    The dynamics of a permanent magnet synchronous machine (PMSM) is analyzed. The study shows that under certain conditions the PMSM is experiencing chaotic behavior. To control these unwanted chaotic oscillations, a nonlinear controller based on the backstepping nonlinear control theory is designed. The objective of the designed control is to stabilize the output chaotic trajectory by forcing it to the nearest constant solution in the basin of attraction. The result is compared with a nonlinear sliding mode controller. The designed controller that based on backstepping nonlinear control was able to eliminate the chaotic oscillations. Also the study shows that the designed controller is mush better than the sliding mode control

  10. Conceptual designs for NLC ubitrons with permanent-magnet wigglers

    International Nuclear Information System (INIS)

    Phillips, R.

    1994-09-01

    This paper describes three embodiments of the ubitron (FEL) amplifier that will be analyzed for possible use on the NLC. The design frequency and power are 11.424 GHz and 200 MW peak rf output power. The baseline against which these conceptual designs are to be evaluated is the PPM-focused 50-MW SIAC klystron, which in simulation shows 65% efficiency. In order to remain competitive in cost and power consumption, only ubitron beam-wave configurations that can use permanent-magnet wigglers are considered

  11. 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......W, respectively) with an iron yoke is subject to losses that exceed the realistic input power, and was therefore deemed infeasible. A generator without the iron yoke was concluded to perform well as a wearable energy harvester. An experimental investigation of a prototype revealed an output power of almost 1 m...

  12. Fuzzy adaptive speed control of a permanent magnet synchronous motor

    Science.gov (United States)

    Choi, Han Ho; Jung, Jin-Woo; Kim, Rae-Young

    2012-05-01

    A fuzzy adaptive speed controller is proposed for a permanent magnet synchronous motor (PMSM). The proposed fuzzy adaptive speed regulator is insensitive to model parameter and load torque variations because it does not need any accurate knowledge about the motor parameter and load torque values. The stability of the proposed control system is also proven. The proposed adaptive speed regulator system is implemented by using a TMS320F28335 floating point DSP. Simulation and experimental results are presented to verify the effectiveness of the proposed fuzzy adaptive speed controller under uncertainties such as motor parameter and load torque variations using a prototype PMSM drive system.

  13. Alloy design of Nd2, Fe14B permanent magnets

    International Nuclear Information System (INIS)

    Horton, J.A.; Herchenroeder, J.W.

    2000-01-01

    This report summarizes the results of research conducted as part of CRADA ORNL94-0279 between Oak Ridge National Laboratory and Magnequench International, Inc. The objective was to gain a better understanding of the fracture process in the rare earth based permanent magnets in order to possibly improve the mechanical properties of these inherently brittle intermetallics. The first part of the study established a technique for measuring a critical property, fracture toughness, and surveying currently available commercial material made by a number of different processes

  14. Vertical and lateral forces when a permanent magnet above a superconductor traverses in arbitrary directions

    Science.gov (United States)

    Yang, Yong

    2008-12-01

    In an actual levitation system composed of high temperature superconductors (HTSs) and permanent magnets (PMs), the levitating bodies may traverse in arbitrary directions. Many previous researchers assumed that the levitating bodies moved in a vertical direction or a lateral direction in order to simplify the problem. In this paper, the vertical and lateral forces acting on the PM are calculated by the modified frozen-image method when a PM above an HTS traverses in arbitrary directions. In order to study the effects of the movement directions on the vertical and lateral forces, comparisons of the forces that act on a PM traversing in a tilted direction with those that act on a PM traversing in a vertical direction or a lateral direction have been presented.

  15. Vertical and lateral forces when a permanent magnet above a superconductor traverses in arbitrary directions

    Energy Technology Data Exchange (ETDEWEB)

    Yang Yong [Key Laboratory of Applied Superconductivity, Chinese Academy of Sciences, Beijing 100190 (China); Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China)], E-mail: yy@mail.iee.ac.cn

    2008-12-15

    In an actual levitation system composed of high temperature superconductors (HTSs) and permanent magnets (PMs), the levitating bodies may traverse in arbitrary directions. Many previous researchers assumed that the levitating bodies moved in a vertical direction or a lateral direction in order to simplify the problem. In this paper, the vertical and lateral forces acting on the PM are calculated by the modified frozen-image method when a PM above an HTS traverses in arbitrary directions. In order to study the effects of the movement directions on the vertical and lateral forces, comparisons of the forces that act on a PM traversing in a tilted direction with those that act on a PM traversing in a vertical direction or a lateral direction have been presented.

  16. Vertical and lateral forces when a permanent magnet above a superconductor traverses in arbitrary directions

    International Nuclear Information System (INIS)

    Yang Yong

    2008-01-01

    In an actual levitation system composed of high temperature superconductors (HTSs) and permanent magnets (PMs), the levitating bodies may traverse in arbitrary directions. Many previous researchers assumed that the levitating bodies moved in a vertical direction or a lateral direction in order to simplify the problem. In this paper, the vertical and lateral forces acting on the PM are calculated by the modified frozen-image method when a PM above an HTS traverses in arbitrary directions. In order to study the effects of the movement directions on the vertical and lateral forces, comparisons of the forces that act on a PM traversing in a tilted direction with those that act on a PM traversing in a vertical direction or a lateral direction have been presented.

  17. Nerve-muscle activation by rotating permanent magnet configurations.

    Science.gov (United States)

    Watterson, Peter A; Nicholson, Graham M

    2016-04-01

    The standard method of magnetic nerve activation using pulses of high current in coils has drawbacks of high cost, high electrical power (of order 1 kW), and limited repetition rate without liquid cooling. Here we report a new technique for nerve activation using high speed rotation of permanent magnet configurations, generating a sustained sinusoidal electric field using very low power (of order 10 W). A high ratio of the electric field gradient divided by frequency is shown to be the key indicator for nerve activation at high frequencies. Activation of the cane toad sciatic nerve and attached gastrocnemius muscle was observed at frequencies as low as 180 Hz for activation of the muscle directly and 230 Hz for curved nerves, but probably not in straight sections of nerve. These results, employing the first prototype device, suggest the opportunity for a new class of small low-cost magnetic nerve and/or muscle stimulators. Conventional pulsed current systems for magnetic neurostimulation are large and expensive and have limited repetition rate because of overheating. Here we report a new technique for nerve activation, namely high-speed rotation of a configuration of permanent magnets. Analytical solutions of the cable equation are derived for the oscillating electric field generated, which has amplitude proportional to the rotation speed. The prototype device built comprised a configuration of two cylindrical magnets with antiparallel magnetisations, made to rotate by interaction between the magnets' own magnetic field and three-phase currents in coils mounted on one side of the device. The electric field in a rectangular bath placed on top of the device was both numerically evaluated and measured. The ratio of the electric field gradient on frequency was approximately 1 V m(-2) Hz(-1) near the device. An exploratory series of physiological tests was conducted on the sciatic nerve and attached gastrocnemius muscle of the cane toad (Bufo marinus). Activation was

  18. Final report: High current capacity high temperature superconducting film based tape for high field magnets

    International Nuclear Information System (INIS)

    Ying Xin

    2000-01-01

    The primary goal of the program was to establish the process parameters for the continuous deposition of high quality, superconducting YBCO films on one meter lengths of buffered RABiTS tape using MOCVD and to characterize the potential utility of the resulting tapes in high field magnet applications

  19. Numerical investigations on applicability of permanent magnet method to crack detection in HTS film

    Energy Technology Data Exchange (ETDEWEB)

    Kamitani, A., E-mail: kamitani@yz.yamagata-u.ac.jp [Yamagata University, 4-3-16, Johnan, Yonezawa, Yamagata 992-8510 (Japan); Takayama, T. [Yamagata University, 4-3-16, Johnan, Yonezawa, Yamagata 992-8510 (Japan); Saitoh, A. [University of Hyogo, 2167, Shosha, Himeji, Hyogo 671-2280 (Japan)

    2014-09-15

    Highlights: • The defect parameter is defined for characterizing a crack position. • The defect parameter shows a remarkable change only near a crack. • A crack detection method is proposed on the basis of the permanent-magnet method. • The high-speed rough detection can be achieved by means of the proposed method. - Abstract: The scanning permanent-magnet (PM) method was originally developed for determining the spatial distribution of the critical current density in a high-temperature superconducting (HTS) film. In the present study, its applicability to the crack detection in an HTS film is investigated numerically. To this end, a defect parameter is defined for characterizing a crack position and it is calculated along various scanning lines. The results of computations show that, only when the scanning position is near a crack, the defect parameter shows a violent change. On the basis of the behavior of the defect parameter, the method for roughly identifying a crack is also proposed.

  20. Numerical investigations on applicability of permanent magnet method to crack detection in HTS film

    International Nuclear Information System (INIS)

    Kamitani, A.; Takayama, T.; Saitoh, A.

    2014-01-01

    Highlights: • The defect parameter is defined for characterizing a crack position. • The defect parameter shows a remarkable change only near a crack. • A crack detection method is proposed on the basis of the permanent-magnet method. • The high-speed rough detection can be achieved by means of the proposed method. - Abstract: The scanning permanent-magnet (PM) method was originally developed for determining the spatial distribution of the critical current density in a high-temperature superconducting (HTS) film. In the present study, its applicability to the crack detection in an HTS film is investigated numerically. To this end, a defect parameter is defined for characterizing a crack position and it is calculated along various scanning lines. The results of computations show that, only when the scanning position is near a crack, the defect parameter shows a violent change. On the basis of the behavior of the defect parameter, the method for roughly identifying a crack is also proposed

  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. A magnetic filter with permanent magnets on the basis of rare earths

    International Nuclear Information System (INIS)

    Zezulka, V.Vaclav; Straka, Pavel; Mucha, Pavel

    2004-01-01

    The article presents the development and construction of a magnetic filter based on the HGMS principle with permanent magnets. It is aimed especially at the assembly of the magnetic circuit using magnets from the material NdFeB. The way of the construction of large magnetic blocks, their magnetization and assembly are described. Further, it contains the measured values of magnetic induction in the middle of the air gap as a function of the width of this gap and of the height of the magnetic blocks in question, as well as the corresponding graphic representation. The high values of the magnetic induction obtained together with favourable price are sufficient reasons for the employment of this type of magnetic circuit in various applications

  3. Using axial magnetized permanent rings to build axial gradient magnetic field

    International Nuclear Information System (INIS)

    Peng Quanling

    2003-01-01

    Axial field produced by an axially magnetized permanent ring was studied. For two permanent magnet rings, if they are magnetized in the same direction, a nearly uniform axial field can be produced; if they are magnetized in opposite direction, an axial gradient field can be produced in the region between the two permanent rings, with the field strength changing from -B 0 to B 0 . A high gradient axial magnetic field has been built by using two axially magnetized permanent rings, the measured field results agree with the PANDIRA calculation very well. It is desirable that the field gradient can be varied to match various requirements. A method to produce the variable gradient field is presented. Axial gradient field can also be used as a beam focusing facility for linear accelerator if axial periodic field can be produced. Its magnetic field is similar to that of a solenoid, in which, large stray field will leak to the outside environment. A method for shielding the outside stray field is discussed

  4. 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.

  5. Nerve–muscle activation by rotating permanent magnet configurations

    Science.gov (United States)

    Nicholson, Graham M.

    2016-01-01

    Key points The standard method of magnetic nerve activation using pulses of high current in coils has drawbacks of high cost, high electrical power (of order 1 kW), and limited repetition rate without liquid cooling.Here we report a new technique for nerve activation using high speed rotation of permanent magnet configurations, generating a sustained sinusoidal electric field using very low power (of order 10 W).A high ratio of the electric field gradient divided by frequency is shown to be the key indicator for nerve activation at high frequencies.Activation of the cane toad sciatic nerve and attached gastrocnemius muscle was observed at frequencies as low as 180 Hz for activation of the muscle directly and 230 Hz for curved nerves, but probably not in straight sections of nerve.These results, employing the first prototype device, suggest the opportunity for a new class of small low‐cost magnetic nerve and/or muscle stimulators. Abstract Conventional pulsed current systems for magnetic neurostimulation are large and expensive and have limited repetition rate because of overheating. Here we report a new technique for nerve activation, namely high‐speed rotation of a configuration of permanent magnets. Analytical solutions of the cable equation are derived for the oscillating electric field generated, which has amplitude proportional to the rotation speed. The prototype device built comprised a configuration of two cylindrical magnets with antiparallel magnetisations, made to rotate by interaction between the magnets’ own magnetic field and three‐phase currents in coils mounted on one side of the device. The electric field in a rectangular bath placed on top of the device was both numerically evaluated and measured. The ratio of the electric field gradient on frequency was approximately 1 V m−2 Hz−1 near the device. An exploratory series of physiological tests was conducted on the sciatic nerve and attached gastrocnemius muscle of the cane toad

  6. Relationship between Magnetic Anisotropy below Pseudogap Temperature and Short-Range Antiferromagnetic Order in High-Temperature Cuprate Superconductor

    Science.gov (United States)

    Morinari, Takao

    2018-06-01

    The central issue in high-temperature cuprate superconductors is the pseudogap state appearing below the pseudogap temperature T*, which is well above the superconducting transition temperature. In this study, we theoretically investigate the rapid increase of the magnetic anisotropy below the pseudogap temperature detected by the recent torque-magnetometry measurements on YBa2Cu3Oy [Y. Sato et al., 10.1038/nphys4205" xlink:type="simple">Nat. Phys. 13, 1074 (2017)]. Applying the spin Green's function formalism including the Dzyaloshinskii-Moriya interaction arising from the buckling of the CuO2 plane, we obtain results that are in good agreement with the experiment and find a scaling relationship. Our analysis suggests that the characteristic temperature associated with the magnetic anisotropy, which coincides with T*, is not a phase transition temperature but a crossover temperature associated with the short-range antiferromagnetic order.

  7. 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.

  8. 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}.

  9. Permanent magnet electron cyclotron resonance plasma source with remote window

    International Nuclear Information System (INIS)

    Berry, L.A.; Gorbatkin, S.M.

    1995-01-01

    An electron cyclotron resonance (ECR) plasma has been used in conjunction with a solid metal sputter target for Cu deposition over 200 mm diameters. The goal is to develop a deposition system and process suitable for filling submicron, high-aspect ratio ULSI features. The system uses a permanent magnet for creation of the magnetic field necessary for ECR, and is significantly more compact than systems equipped with electromagnets. A custom launcher design allows remote microwave injection with the microwave entrance window shielded from the copper flux. When microwaves are introduced at an angle with respect to the plasma, high electron densities can be produced with a plasma frequency significantly greater than the electron cyclotron frequency. Copper deposition rates of 1000 A/min have been achieved

  10. 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).

  11. The equilibrium magnetization of granular high temperature superconductors in low fields. Pt. 1

    International Nuclear Information System (INIS)

    Ruppel, S.; Michels, G.; Geus, H.; Kalenborn, J.; Schlabitz, W.; Wohlleben, D.

    1990-01-01

    We report the temperature and field dependence of the Meissner flux expulsion of sintered pellets of YBa 2 (Cu 1-x Fe x ) 3 O 7-y with 0≤x≤0.08. In all samples the flux expulsion remains incomplete (-4 πχ∼1/3) down to fields, which are much smaller than H c1 , but for H≤2 Oe they all finally exhibit a full Meissner effect and are therefore fully superconducting. The expulsion in 2 Oe decreases to near 30% by aging of the grain boundaries and goes back to near 100% after their reoxidation, all at a fixed and sharp T c of 93 K. The data are interpreted in terms of equilibrium properties of granular high temperature superconductors on the basis of an analysis, which is described in detail in the following paper. An average cross-section of the superconducting 'grains' in the CuO planes of 4 μm 2 is extracted from the temperature and field dependence of the spontaneous flux expulsion. These 'grains' lie within the much larger crystallographic grains and are bordered by planar defects. Superconducting loops around these planar defects are responsible for the final flux expulsion in H c can also be extracted from the data. One finds ΔT c ≤1 K in the orthorhombic phase (x ≤ 0.02), while in the quasitetragonal phase, ΔT c increases from 1 to 16 K for 0.02 < x ≤ 0.08. (orig.)

  12. Calculating transport AC losses in stacks of high temperature superconductor coated conductors with magnetic substrates using FEM

    International Nuclear Information System (INIS)

    Ainslie, Mark D.; Flack, Tim J.; Campbell, Archie M.

    2012-01-01

    Properties of stacks of HTS coated conductors with and without a magnetic substrate. Non-magnetic substrate model is consistent with existing methods. Presence of a magnetic substrate increases the total AC loss of the stack. Differences and similarities between certain tapes within stacks are explained. Ferromagnetic loss of substrate negligible in most cases except small currents/fields. In this paper, the authors investigate the electromagnetic properties of stacks of high temperature superconductor (HTS) coated conductors with a particular focus on calculating the total transport AC loss. The cross-section of superconducting cables and coils is often modeled as a two-dimensional stack of coated conductors, and these stacks can be used to estimate the AC loss of a practical device. This paper uses a symmetric two dimensional (2D) finite element model based on the H formulation, and a detailed investigation into the effects of a magnetic substrate on the transport AC loss of a stack is presented. The number of coated conductors in each stack is varied from 1 to 150, and three types of substrate are compared: non-magnetic weakly magnetic and strongly magnetic. The non-magnetic substrate model is comparable with results from existing models for the limiting cases of a single tape (Norris) and an infinite stack (Clem). The presence of a magnetic substrate increases the total AC loss of the stack, due to an increased localized magnetic flux density, and the stronger the magnetic material, the further the flux penetrates into the stack overall. The AC loss is calculated for certain tapes within the stack, and the differences and similarities between the losses throughout the stack are explained using the magnetic flux penetration and current density distributions in those tapes. The ferromagnetic loss of the substrate itself is found to be negligible in most cases, except for small magnitudes of current. Applying these findings to practical applications, where AC

  13. Analysis and optimization of hybrid excitation permanent magnet synchronous generator for stand-alone power system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huijun, E-mail: huijun024@gmail.com [School of Instrumentation Science and Opto-electronics Engineering, Beihang University (China); Qu, Zheng; Tang, Shaofei; Pang, Mingqi [School of Instrumentation Science and Opto-electronics Engineering, Beihang University (China); Zhang, Mingju [Shanghai Aerospace Control Technology Institute, Shanghai (China)

    2017-08-15

    Highlights: • One novel permanent magnet generator structure has been proposed to reduce voltage regulation ratio. • Finite element method and equivalent circuit methods are both employed to realize rapid generator design. • Design of experiment (DOE) method is used to optimize permanent magnet shape for reduce voltage waveform distortion. • The obtained analysis and experiment results verify the proposed design methods. - Abstract: In this paper, electromagnetic design and permanent magnet shape optimization for permanent magnet synchronous generator with hybrid excitation are investigated. Based on generator structure and principle, design outline is presented for obtaining high efficiency and low voltage fluctuation. In order to realize rapid design, equivalent magnetic circuits for permanent magnet and iron poles are developed. At the same time, finite element analysis is employed. Furthermore, by means of design of experiment (DOE) method, permanent magnet is optimized to reduce voltage waveform distortion. Finally, the validity of proposed design methods is validated by the analytical and experimental results.

  14. Analysis and optimization of hybrid excitation permanent magnet synchronous generator for stand-alone power system

    International Nuclear Information System (INIS)

    Wang, Huijun; Qu, Zheng; Tang, Shaofei; Pang, Mingqi; Zhang, Mingju

    2017-01-01

    Highlights: • One novel permanent magnet generator structure has been proposed to reduce voltage regulation ratio. • Finite element method and equivalent circuit methods are both employed to realize rapid generator design. • Design of experiment (DOE) method is used to optimize permanent magnet shape for reduce voltage waveform distortion. • The obtained analysis and experiment results verify the proposed design methods. - Abstract: In this paper, electromagnetic design and permanent magnet shape optimization for permanent magnet synchronous generator with hybrid excitation are investigated. Based on generator structure and principle, design outline is presented for obtaining high efficiency and low voltage fluctuation. In order to realize rapid design, equivalent magnetic circuits for permanent magnet and iron poles are developed. At the same time, finite element analysis is employed. Furthermore, by means of design of experiment (DOE) method, permanent magnet is optimized to reduce voltage waveform distortion. Finally, the validity of proposed design methods is validated by the analytical and experimental results.

  15. 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.

  16. Interplay between magnetism and superconductivity in iron based high temperature superconductors

    International Nuclear Information System (INIS)

    Price, Stephen

    2013-01-01

    In this thesis, magnetic properties of a series of different Fe-based superconducting materials have been studied by means of neutron scattering techniques. Magnetic correlations in underdoped Ba(Fe 0.95 Co 0.05 ) 2 As 2 have been investigated for three phases of the phase diagram. It was possible to detect the spin gap and spin resonance signal, two features of the particle hole excitation spectrum at Q=(0.5,0.5,0), characteristic for the superconducting phase. The spin wave excitations present in the ordered phase have been analyzed quantitatively in terms of a linear spin wave model, whereas a spin diffusion model was applied to the collective excitations of the paramagnetic phase. However, it was found that both models can be applied to excitations in all three phases. In optimally doped CaFe 0.88 Co 0.12 AsF, a spin resonance signal was detected as part of the spin excitation spectrum at Q=(0.5,0.5,0). The observation of the spin resonance signal supports the s ± symmetry of the superconducting gap function. In the undoped CaFeAsF compound three dimensional spin wave like excitations of the static Fe-SDW order have been observed at Q AFM =(0.5,0.5,0.5), for temperatures below T N . Above T N and for energies below 20 meV, the spin wave like excitations are replaced by short range two dimensional paramagnetic excitations, which persist up to 270 K. In superconducting FeSe 0.5 Te 0.5 polarized neutron scattering investigations revealed the magnetic nature of the spin resonance signal and the excitation spectrum at Q=(0.5,0.5,0) up to 30 meV. The whole excitation spectrum including the spin resonance signal consists of an isotropic distribution of spin excitations with magnetic moments fluctuating in the ab-plane and perpendicular to the ab-plane, χ ab ''(Q,ω)∼χ c ''(Q,ω). In Eu(Fe 1-x Co x ) 2 As 2 and EuFe 2 (As 1-x P x ) 2 the effect of impurity doping on the static order of the magnetic lattice of the Eu 2+ -moments has been studied by means of

  17. Analysis and optimization of hybrid excitation permanent magnet synchronous generator for stand-alone power system

    Science.gov (United States)

    Wang, Huijun; Qu, Zheng; Tang, Shaofei; Pang, Mingqi; Zhang, Mingju

    2017-08-01

    In this paper, electromagnetic design and permanent magnet shape optimization for permanent magnet synchronous generator with hybrid excitation are investigated. Based on generator structure and principle, design outline is presented for obtaining high efficiency and low voltage fluctuation. In order to realize rapid design, equivalent magnetic circuits for permanent magnet and iron poles are developed. At the same time, finite element analysis is employed. Furthermore, by means of design of experiment (DOE) method, permanent magnet is optimized to reduce voltage waveform distortion. Finally, the validity of proposed design methods is validated by the analytical and experimental results.

  18. Magnetic and Engineering Analysis of an Adjustable Strength Permanent Magnet Quadrupole

    CERN Document Server

    Gottschalk, Stephen C

    2005-01-01

    Magnetic and engineering analyses used in the design of an adjustable strength permanent magnet quadrupole will be reported. The quadrupole designed has a pole length of 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient * length (GL) of 68.7Tesla. Analyses of magnetic strength, field quality, magnetic centerline, temperature compensation and dynamic eddy currents induced during field adjustments will be presented. Magnet sorting strategies, pole positioning sensitivity, component forces, and other sensitivity analyses will be presented. Engineering analyses of stress, deflection and thermal effects as well as compensation strategies will also be shown.

  19. A new nonlinear magnetic circuit model for dynamic analysis of interior permanent magnet synchronous motor

    International Nuclear Information System (INIS)

    Nakamura, Kenji; Saito, Kenichi; Watanabe, Tadaaki; Ichinokura, Osamu

    2005-01-01

    Interior permanent magnet synchronous motors (IPMSMs) have high efficiency and torque, since the motors can utilize reluctance torque in addition to magnet torque. The IPMSMs are widely used for electric household appliances and electric bicycles and vehicles. A quantitative analysis method of dynamic characteristics of the IPMSMs, however, has not been clarified fully. For optimum design, investigation of dynamic characteristics considering magnetic nonlinearity is needed. This paper presents a new nonlinear magnetic circuit model of an IPMSM, and suggests a dynamic analysis method using the proposed magnetic circuit model

  20. The analysis of the permanent magnet motor using the new magnetic field analysis

    International Nuclear Information System (INIS)

    Shimoji, Hiroyasu; Enokizono, Masato; Todaka, Takashi

    2002-01-01

    In this paper iron loss analysis of the permanent magnet motor considering anisotropy of magnetic material is carried out. Recently the magnetic material can be measured using of vector quantity technique. Non-oriented silicon steel sheets for the iron core material have the anisotropy. Therefore, it is necessary to carry out the analysis considering the anisotropy of the magnetic material. We used the magnetic field analysis, which consider the anisotropy by combining finite element method with the E and S (Enokizono and Soda) modeling. (Author)

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

    International Nuclear Information System (INIS)

    Ohashi, S.; Kobayashi, S.

    2009-01-01

    Magnetic levitation using the pinning force of the YBaCuO high-T 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.

  2. Study of the magnetic field distribution in high-temperature superconductors using muon-spin-rotation

    International Nuclear Information System (INIS)

    Zimmermann, P.R.

    1994-01-01

    Detailed and systematic μ + SR experiments have been performed in order to (i) investigate the temperature dependence of the magnetic penetration depth in various cuprate high-T c superconductors and (ii) study the vortex structures and dynamics in the highly anisotropic Bi 2 Sr 2 CaCu 2 O 8 . The μ + SR method and its application to superconductivity has been discussed. The positive muon is a microscopic probe of the local magnetic field in the bulk of a sample. The μ + SR technique can therefore measure the magnetic field distribution p(B) which is determined by the flux structure in the superconductor. The second moment (ΔB 2 ) of p(B) is closely related to the magnetic penetration depth λ, a fundamental parameter of superconductivity. It has been shown that in high-quality sintered samples a good estimate of the in-plane penetration depth λ ab can be given in terms of the muon-depolarization rate σ. Since the penetration depth is related to the superconducting order parameter, the temperature dependence of the penetration depth is a potential probe of the pairing state. Systematic measurements of the temperature dependence of σ have been performed in sintered samples of high quality in various members of the Y123 family, Pb and Y doped Tl1212 family, and also in Y124 and Bi2212. It is found that the extracted temperature behaviour of λ ab -2 is characteristic of each compound. This can be interpreted as a varying coupling strength in these systems. In well oxygenated Y123, λ ab -2 (T) is well described by the two-fluid model indicating strong coupling. The rest of the cuprates investigated show a λ ab -2 (T) which points to weaker coupling, with λ ab -2 (T) of highly oxygen deficient Y123 being similar to the weak-coupling BCS prediction. In the Y123 family the decreasing coupling strength with decreasing oxygen content is related to the increasing anisotropy. Comparison with theoretical predictions of λ ab -2 (T) revealed that the observed

  3. 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.

  4. High temperature magnetic properties of Co(FeY){sub 2}O{sub 4} synthesized by combustion reaction

    Energy Technology Data Exchange (ETDEWEB)

    Alves, Thiago Eduardo Pereira, E-mail: thiago.ifgo@gmail.com [Instituto Federal de Educacao, Ciencia e Tecnologia de Goias (IFGO), Goiania (Brazil); Franco Junior, Adolfo [Universidade Federal de Goias (UFG), Goiania (Brazil)

    2016-07-01

    Full text: Cobalt ferrite is widely studied due to its interesting magnetic behavior at room temperature. However, many technical applications require temperatures that are above that. Thus, it is necessary to understand how some magnetic properties, such as saturation magnetization (Ms), remanent magnetization (Mr), and coercivity (Hc), may behave at high temperatures [1]. Among several methods to synthesize cobalt ferrites, combustion reaction method is intensively used because it is inexpensive, fast and has good control on the stoichiometry. This method is based on the chemistry of propellants and explosives [2]. Therefore, we have prepared a series of nanoparticles of CoFe{sub (2-x)}Y{sub x}O{sub 4}, with x ranging from 0.00 to 0.04, by combustion reaction method. The crystal structure and morphology were characterized by X-ray diffraction (XRD) using Rietveld refinement and transmission electron microscopy (TEM), respectively. Nanocrystalline particles structures in the typical phase of spinel were observed on diffractograms. Micrographies showed high crystalline powders for the particles and particles size within nanoscale range. The magnetic properties were measured by vibrating sample magnetometry (VSM) in broad range of temperature (300-850K). Saturation magnetization (Ms) decreases with Y doping increase, while Hc increases, being about 1.8 higher than the undoped sample. Furthermore, Curie temperature increases with Y doping increase. These magnetic properties were discussed in terms of the particle interactions induced by the thermal fluctuations, cation distribution, and ions exchange between yttrium and cobalt atoms in A-B sites in the cubic structure [3]. References: [1] A. Franco, Jr. and F. C. e Silva, Applied Physics Letters 96, 172505, (2010). 525 [2] S.R. Jain, et al, Combustion and flame 40, 71-79, (1981). [3] A. Franco Jr. et al. Journal of Alloys and Compounds 680, 198-205, (2016). (author)

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

    International Nuclear Information System (INIS)

    Perini, E; Giunchi, G

    2009-01-01

    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 MgB 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 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 c . We verified the very stable characteristics of the induced magnetization after several cycles of relative movements of the PM and the superconducting cylinder.

  6. Permanent magnet working point ripple in synchronous generators

    Directory of Open Access Journals (Sweden)

    Stefan Sjökvist

    2017-04-01

    Full Text Available Permanent magnets (PMs are today widely used in electrical machines of all sorts. With their increase in popularity, the amount of research has increased as well. In this study, the magnetic flux density ripple of the working point of the PMs in a 100 kW PM synchronous generator has been investigated for three different load cases: no load, AC load, and DC load. The PMs will be subjected to a shift in working point as a consequence of the characteristics of the electrical loading. This study is based on finite element method simulations where the ripple of the magnetic flux density in the PMs was recorded at three positions within a PM. The slot harmonic of 7.5 times the electrical frequency (f(el was present in the results for all load cases, but mainly at the surface of the PM, as expected. Results showed an unexpected harmonic of 1.5 f(el, assumed to be an undertone of the slot harmonics. The 6f(el harmonic for the DC load case was significantly higher than for the AC load case and is caused by the current fluctuation during passive rectification. For the studied machine, the added harmonics in the magnetic field due to passive rectification are less than the slot-related harmonics.

  7. Interplay between magnetism and superconductivity in iron based high temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Price, Stephen

    2013-07-01

    In this thesis, magnetic properties of a series of different Fe-based superconducting materials have been studied by means of neutron scattering techniques. Magnetic correlations in underdoped Ba(Fe{sub 0.95}Co{sub 0.05}){sub 2}As{sub 2} have been investigated for three phases of the phase diagram. It was possible to detect the spin gap and spin resonance signal, two features of the particle hole excitation spectrum at Q=(0.5,0.5,0), characteristic for the superconducting phase. The spin wave excitations present in the ordered phase have been analyzed quantitatively in terms of a linear spin wave model, whereas a spin diffusion model was applied to the collective excitations of the paramagnetic phase. However, it was found that both models can be applied to excitations in all three phases. In optimally doped CaFe{sub 0.88}Co{sub 0.12}AsF, a spin resonance signal was detected as part of the spin excitation spectrum at Q=(0.5,0.5,0). The observation of the spin resonance signal supports the s{sub ±} symmetry of the superconducting gap function. In the undoped CaFeAsF compound three dimensional spin wave like excitations of the static Fe-SDW order have been observed at Q{sub AFM}=(0.5,0.5,0.5), for temperatures below T{sub N}. Above T{sub N} and for energies below 20 meV, the spin wave like excitations are replaced by short range two dimensional paramagnetic excitations, which persist up to 270 K. In superconducting FeSe{sub 0.5}Te{sub 0.5} polarized neutron scattering investigations revealed the magnetic nature of the spin resonance signal and the excitation spectrum at Q=(0.5,0.5,0) up to 30 meV. The whole excitation spectrum including the spin resonance signal consists of an isotropic distribution of spin excitations with magnetic moments fluctuating in the ab-plane and perpendicular to the ab-plane, χ{sub ab}''(Q,ω)∼χ{sub c}''(Q,ω). In Eu(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} and EuFe{sub 2}(As{sub 1-x}P{sub x}){sub 2} the effect of

  8. 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.

  9. Enhancement of magnetic coupling between permanent magnets and bulk superconductors through iron embedding

    International Nuclear Information System (INIS)

    Seki, H.; Kurabayashi, H.; Suzuki, A.; Ikeda, M.; Akiyama, S.; Murakami, M.

    2009-01-01

    Magnetic torque can be transferred without contact through the coupling of permanent magnets (PM) and bulk superconductors (BSC). For this purpose, permanent magnets should have multiple pole configuration like NSNS. The magnitude of the transferable torque depends on the field strength and the gap between PM and BSC. It was found that the torque decays quickly with the gap. In order to enhance the strength of transferable magnetic torque, we prepared bulk Y-Ba-Cu-O superconductors for which Fe bars are embedded. Holes about 1 mm in diameter were mechanically drilled into bulk Y-Ba-Cu-O, and Fe bars about 0.9 mm in diameter were inserted followed by impregnation of Bi-Pb-Sn alloys with low melting points. The composite of Y-Ba-Cu-O and Fe bars attract magnetic fields generated from permanent magnet before cooling, and thereby magnetic coupling will be improved. We have found that the magnetic torque force can be greatly enhanced through iron embedding.

  10. Thickness dependence of the levitation performance of double-layer high-temperature superconductor bulks above a magnetic rail

    International Nuclear Information System (INIS)

    Sun, R.X.; Zheng, J.; Liao, X.L.; Che, T.; Gou, Y.F.; He, D.B.; Deng, Z.G.

    2014-01-01

    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

  11. 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.

  12. Quantum oscillations in the parent magnetic phase of an iron arsenide high temperature superconductor

    International Nuclear Information System (INIS)

    Sebastian, Suchitra E; Gillett, J; Lau, P H C; Lonzarich, G G; Harrison, N; Mielke, C H; Singh, D J

    2008-01-01

    We report measurements of quantum oscillations in SrFe 2 As 2 -which is an antiferromagnetic parent of the iron arsenide family of superconductors-known to become superconducting under doping and the application of pressure. The magnetic field and temperature dependences of the oscillations between 20 and 55 T in the liquid helium temperature range suggest that the electronic excitations are those of a Fermi liquid. We show that the observed Fermi surface comprising small pockets is consistent with the formation of a spin-density wave. Our measurements thus demonstrate that high T c superconductivity can occur on doping or pressurizing a conventional metallic spin-density wave state. (fast track communication)

  13. The Permanent Magnet Operating Mechanism of Double Coil Parallel Driven at a High Speed

    Directory of Open Access Journals (Sweden)

    WEI Xau-Lao

    2017-02-01

    Full Text Available Abstract:Operating mechanism is the main part of breaker,and the quality of breaker will directly influence the safe operation of power system. Because of the continuous improvement requirements of switch,in order to mak this actuator faster and more powerful closing,this paper proposes a double coil parallel driven permanent magnet actuator at a high speed. This paper expounds the working principle of single and double coil parallel driven permanent magnet actuator. It uses Ansoft building model and contrasts test results. In prance we designed and produced the single and double coil parallel driven permanent magnet actuator for experimental study. The simulation and experiment results show that double coil parallel driven permanent magnet actuator,compared with single coil parallel driven permanent magnet actuator,has a better and faster action performance. Thus,the double coil parallel driven permanent magnet actuator achieves a kind of optimization.

  14. Three-dimensional analytical field calculation of pyramidal-frustum shaped permanent magnets

    NARCIS (Netherlands)

    Janssen, J.L.G.; Paulides, J.J.H.; Lomonova, E.

    2009-01-01

    This paper presents a novel method to obtain fully analytical expressions of the magnetic field created by a pyramidal-frustum shaped permanent magnet. Conventional analytical tools only provide expressions for cuboidal permanent magnets and this paper extends these tools to more complex shapes. A

  15. 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...

  16. 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

  17. Program for tests on magnetic bearing suspended rotor dynamics for gas turbine high temperature reactor (GTHTR300)

    International Nuclear Information System (INIS)

    Takada, Shoji; Takizuka, Takakazu; Kunitomi, Kazuhiko; Kosugiyama, Shinichi; Yan, Xing

    2003-01-01

    A program for test on rotor dynamics was planned for the turbo-machine of the Gas Turbine High Temperature Reactor (GTHTR300). The rotor system of the turbo-machine consists of a turbo-compressor rotor and a generator rotor connected with a flexible coupling, each suspended with two radial magnetic bearings. The rotors, which are flexible rotors, pass over the critical speeds of bending mode. The magnetic bearing is required to have a high load capacity, about 10 times larger than any built thus far to support a flexible rotor. In the rotor design, the standard limit of the vibration amplitude of 75 μm at the rated rotational speed of 3,600 rpm was fulfilled by optimizing the stiffness of the magnetic bearings. A test apparatus was designed to verify the design of the magnetic bearing suspended turbo-machine rotor of the GTHTR300. The test apparatus is composed of 1/3-scale test rotors, which are connected with a flexible coupling and driven by a variable speed motor. The test magnetic bearing was designed within the state-of-the-art technology to have a load capacity about 1/10 of that of the actual one. The test rotors were designed to closely simulate the critical speeds and vibration modes of the actual ones. This paper shows the test apparatus and the test plan for the magnetic bearing suspended rotor system. The present study is entrusted from the Ministry of Education, Culture, Sports, Science and Technology of Japan. (author)

  18. Permanent magnets for production and use of high energy particle beams

    International Nuclear Information System (INIS)

    Halbach, K.

    1985-03-01

    In the last few years, permanent magnet systems have begun to play a dominant role in the generation of synchrotron radiation and the operation of free electron lasers. Similarly, permanent magnets can lead to significant improvements of accelerators and systems that use them. The general conditions are discussed under which one can expect benefits from permanent magnets, and a number of specific applications will be described in detail

  19. 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.

  20. A National Collaboratory to Advance the Science of High Temperature Plasma Physics for Magnetic Fusion

    International Nuclear Information System (INIS)

    Schissel, David P.; Abla, G.; Burruss, J. R.; Feibush, E.; Fredian, T. W.; Goode, M. M.; Greenwald, M. J.; Keahey, K.; Leggett, T.; Li, K.; McCune, D. C.; Papka, M. E.; Randerson, L.; Sanderson, A.; Stillerman, J.; Thompson, M. R.; Uram, T.; Wallace, G.

    2012-01-01

    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.

  1. Relationship of electrical, magnetic, and mechanical properties to processing in high-temperature superconductors

    International Nuclear Information System (INIS)

    Blendell, J.E.; Chiang, C.K.; Cranmer, D.C.

    1987-01-01

    The interrelation between processing, microstructure, and properties is an important factor in understanding the behavior of ceramic materials. This type of understanding will be particularly important in the development of the new high T/sub c/ superconducting ceramic oxides of the type Ba/sub 2/YCu/sub 3/O/sub 7-x/. As an initial effort in understanding these relations, a number of properties have been measured for these superconducting ceramics and related to their microstructure and processing sequence. The Ba/sub 2/YCu/sub 3/O/sub 7-x/ ceramics were prepared by powder processing techniques, followed by dry pressing and sintering in both air and flowing oxygen at various temperatures. The sintered bodies were annealed at various temperatures and environments. Superconducting properties, such as the transition temperature and the width of the transition, were measured by both electrical conductivity and AC magnetic susceptibility; both of these properties show a strong sensitivity to annealing temperature and atmosphere. The microstructure and density were also strongly dependent on processing conditions. In this regard, compositional mapping proved to be an important technique for quantifying microstructural variations. Mechanical properties, such as elastic modulus, hardness, and fracture toughness, which will be important for the reliable use of these materials in large scale structures, were also determined

  2. Conceptual design of a compact high gradient quadrupole magnet of varying strength using permanent magnets

    Directory of Open Access Journals (Sweden)

    Gautam Sinha

    2018-02-01

    Full Text Available A concept is presented to design magnets using cylindrical-shaped permanent-magnet blocks, where various types of magnetic fields can be produced by either rotating or varying the size of the magnetic blocks within a given mechanical structure. A general method is introduced to calculate the 3D magnetic field produced by a set of permanent magnets. An analytical expression of the 2D field and the condition to generate various magnetic fields like dipole, quadrupole, and sextupole are derived. Using the 2D result as a starting point, a computer code is developed to get the optimum orientation of the magnets to obtain the user-specific target field profile over a given volume in 3D. Designs of two quadrupole magnets are presented, one using 12 and the other using 24 permanent-magnet blocks. Variation of the quadrupole strength is achieved using tuning coils of a suitable current density and specially designed end tubes. A new concept is introduced to reduce the integrated quadrupole field strength by inserting two hollow cylindrical tubes made of iron, one at each end. This will not affect the field gradient at the center but reduce the integrated field strength by shielding the magnetic field near the ends where the tubes are inserted. The advantages of this scheme are that it is easy to implement, the magnetic axis will not shift, and it will prevent interference with nearby devices. Around 40% integrated field variation is achieved using this method in the present example. To get a realistic estimation of the field quality, a complete 3D model using a nonlinear B-H curve is also studied using a finite-element-based computer code. An example to generate around an 80  T/m quadrupole field gradient is also presented.

  3. Conceptual design of a compact high gradient quadrupole magnet of varying strength using permanent magnets

    Science.gov (United States)

    Sinha, Gautam

    2018-02-01

    A concept is presented to design magnets using cylindrical-shaped permanent-magnet blocks, where various types of magnetic fields can be produced by either rotating or varying the size of the magnetic blocks within a given mechanical structure. A general method is introduced to calculate the 3D magnetic field produced by a set of permanent magnets. An analytical expression of the 2D field and the condition to generate various magnetic fields like dipole, quadrupole, and sextupole are derived. Using the 2D result as a starting point, a computer code is developed to get the optimum orientation of the magnets to obtain the user-specific target field profile over a given volume in 3D. Designs of two quadrupole magnets are presented, one using 12 and the other using 24 permanent-magnet blocks. Variation of the quadrupole strength is achieved using tuning coils of a suitable current density and specially designed end tubes. A new concept is introduced to reduce the integrated quadrupole field strength by inserting two hollow cylindrical tubes made of iron, one at each end. This will not affect the field gradient at the center but reduce the integrated field strength by shielding the magnetic field near the ends where the tubes are inserted. The advantages of this scheme are that it is easy to implement, the magnetic axis will not shift, and it will prevent interference with nearby devices. Around 40% integrated field variation is achieved using this method in the present example. To get a realistic estimation of the field quality, a complete 3D model using a nonlinear B -H curve is also studied using a finite-element-based computer code. An example to generate around an 80 T /m quadrupole field gradient is also presented.

  4. Interfacial Phenomena of Magnetic Fluid with Permanent Magnet in a Longitudinally Excited Container

    International Nuclear Information System (INIS)

    Sudo, Seiichi; Wakuda, Hirofumi; Yano, Tetsuya

    2008-01-01

    This paper describes the magnetic fluid sloshing in a longitudinally excited container. Liquid responses of magnetic fluid with a permanent magnet in a circular cylindrical container subject to vertical vibration are investigated. Experiments are performed on a vibration- testing system which provided longitudinal excitation. A cylindrical container made with the acrylic plastic is used in the experiment. A permanent magnet is in the state of floating in a magnetic fluid. The disk-shaped and ring-shaped magnets are examined. The different interfacial phenomena from the usual longitudinal liquid sloshing are observed. It is found that the wave motion frequency of magnetic fluid with a disk-shaped magnet in the container subject to vertical vibration is exactly same that of the excitation. In the case of ring-shaped magnet, the first symmetrical mode of one-half subharmonic response is dominant at lower excitation frequencies. The magnetic fluid disintegration of the free surface was also observed by a high-speed video camera system

  5. Interfacial Phenomena of Magnetic Fluid with Permanent Magnet in a Longitudinally Excited Container

    Science.gov (United States)

    Sudo, Seiichi; Wakuda, Hirofumi; Yano, Tetsuya

    2008-02-01

    This paper describes the magnetic fluid sloshing in a longitudinally excited container. Liquid responses of magnetic fluid with a permanent magnet in a circular cylindrical container subject to vertical vibration are investigated. Experiments are performed on a vibration- testing system which provided longitudinal excitation. A cylindrical container made with the acrylic plastic is used in the experiment. A permanent magnet is in the state of floating in a magnetic fluid. The disk-shaped and ring-shaped magnets are examined. The different interfacial phenomena from the usual longitudinal liquid sloshing are observed. It is found that the wave motion frequency of magnetic fluid with a disk-shaped magnet in the container subject to vertical vibration is exactly same that of the excitation. In the case of ring-shaped magnet, the first symmetrical mode of one-half subharmonic response is dominant at lower excitation frequencies. The magnetic fluid disintegration of the free surface was also observed by a high-speed video camera system.

  6. Investigation of the Capture of Magnetic Particles From High-Viscosity Fluids Using Permanent Magnets.

    Science.gov (United States)

    Garraud, Alexandra; Velez, Camilo; Shah, Yash; Garraud, Nicolas; Kozissnik, Bettina; Yarmola, Elena G; Allen, Kyle D; Dobson, Jon; Arnold, David P

    2016-02-01

    This paper investigates the practicality of using a small, permanent magnet to capture magnetic particles out of high-viscosity biological fluids, such as synovial fluid. Numerical simulations are used to predict the trajectory of magnetic particles toward the permanent magnet. The simulations are used to determine a "collection volume" with a time-dependent size and shape, which determines the number of particles that can be captured from the fluid in a given amount of time. The viscosity of the fluid strongly influences the velocity of the magnetic particles toward the magnet, hence, the collection volume after a given time. In regards to the design of the magnet, the overall size is shown to most strongly influence the collection volume in comparison to the magnet shape or aspect ratio. Numerical results showed good agreement with in vitro experimental magnetic collection results. In the long term, this paper aims to facilitate optimization of the collection of magnetic particle-biomarker conjugates from high-viscosity biological fluids without the need to remove the fluid from a patient.

  7. 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

  8. A National Collaboratory To Advance The Science Of High Temperature Plasma Physics For Magnetic Fusion

    International Nuclear Information System (INIS)

    Sanderson, Allen R.; Johnson, Christopher R.

    2006-01-01

    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

  9. Fixed-Time Stability Analysis of Permanent Magnet Synchronous Motors with Novel Adaptive Control

    Directory of Open Access Journals (Sweden)

    Maoxing Liu

    2017-01-01

    Full Text Available We firstly investigate the fixed-time stability analysis of uncertain permanent magnet synchronous motors with novel control. Compared with finite-time stability where the convergence rate relies on the initial permanent magnet synchronous motors state, the settling time of fixed-time stability can be adjusted to desired values regardless of initial conditions. Novel adaptive stability control strategy for the permanent magnet synchronous motors is proposed, with which we can stabilize permanent magnet synchronous motors within fixed time based on the Lyapunov stability theory. Finally, some simulation and comparison results are given to illustrate the validity of the theoretical results.

  10. A study on stable levitation of permanent magnet transportation system with coreless linear synchronous motor

    Energy Technology Data Exchange (ETDEWEB)

    Hiwaki, H [Dept. of Electrical and Electronic Engineering, Musashi Inst. of Technology, Tokyo (Japan); Watada, M [Dept. of Electrical and Electronic Engineering, Musashi Inst. of Technology, Tokyo (Japan); Torii, S [Dept. of Electrical and Electronic Engineering, Musashi Inst. of Technology, Tokyo (Japan); Ebihara, D [Dept. of Electrical and Electronic Engineering, Musashi Inst. of Technology, Tokyo (Japan)

    1996-12-31

    In the permanent magnet levitation system, it is impossible to stabilize the motion of the vehicle in both levitation and guidance directions only by permanent magnet. Therefore, the authors proposed the combined system of permanent magnet for levitation and coreless linear synchronous motor (coreless LSM). To design the coreless coils for LSM, the method to calculate the spring coefficient between coreless coil and permanent magnet for LSM is shown. By using this method, the spring coefficients of the three coil arrangements are compared and coreless coil is designed. Furthermore, the authors showed the possibility of stabilizing the motion of the levitation system with coreless LSM. (orig.)

  11. Magnetic Qualification of Permanent Magnet Quadrupoles for CERN’s Linac4

    CERN Document Server

    Buzio, M; Lombardi, A; Mateo, F

    2012-01-01

    This paper summarizes the results of the magnetic measurements done to qualify prototypes and series permanent- magnet quadrupoles for the new Linac4, currently in construction at CERN. The results, obtained with a combination of stretched wire and rotating coil techniques, include the individually tuned integrated field gradient, multipoles, magnetic axis and field direction. These magnets are characterized by a challengingly small 22 mm aperture diameter and we illustrate the methods adopted to guarantee instrument calibration, along with the estimated accuracies of the measured quantities and their impact on beam optics.

  12. Experimental verification and analytical calculation of unbalanced magnetic force in permanent magnet machines

    Directory of Open Access Journals (Sweden)

    Kyung-Hun Shin

    2017-05-01

    Full Text Available In this study, an exact analytical solution based on Fourier analysis is proposed to compute the unbalanced magnetic force in a permanent magnet machine. The magnetic field solutions are obtained by using a magnetic vector potential and by selecting the appropriate boundary conditions. Based on these field solutions, the force characteristics are also determined analytically. All analytical results were extensively validated with nonlinear two-dimensional finite element analysis and experimental results. Using proposed method, we investigated the influence on the UMF according to machine parameters. Therefore, the proposed method should be very useful in initial design and optimization process of PM machines for UMF analysis.

  13. 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.

  14. Hybrid permanent magnet quadrupoles for the Recycler Ring at Fermilab

    International Nuclear Information System (INIS)

    Brown, B.C.; Pruss, S.M.; Foster, G.W.; Glass, H.D.; Harding, D.J.; Jackson, G.R.; May, M.R.; Nicol, T.H.; Ostiguy, J.-F.; Schlabach, R.; Volk, J.T.

    1997-10-01

    Hybrid Permanent Magnet Quadrupoles are used in several applications for the Fermilab Recycler Ring and associated beam transfer lines. Most of these magnets use a 0.6096 m long iron shell and provide integrated gradients up to 1.4 T-m/m with an iron pole tip radius of 41.6 mm. A 58.4 mm pole radius design is also required. Bricks of 25. 4 mm thick strontium ferrite supply the flux to the back of the pole to produce the desired gradients (0.6 to 2.75 T/m). For temperature compensation, Ni-Fe alloy strips are interspersed between ferrite bricks to subtract flux in a temperature dependent fashion. Adjustments of the permeance of each pole using iron between the pole and the flux return shell permits the matching of pole potentials. Magnetic potentials of the poles are adjusted to the desired value to achieve the prescribed strength and field uniformity based on rotating coil harmonic measurements. Procurement, fabrication, pole potential adjustment, and measured fields will be reported

  15. Design of permanent magnet quadrupole for LEHIPA DTL

    International Nuclear Information System (INIS)

    Mathew, Jose V.; Rao, S.V.L.S.; Krishnagopal, S.; Singh, P.

    2011-01-01

    The drift tube linac (DTL) of the low energy high intensity proton accelerator (LEHIPA) has been designed to accelerate 30 mA proton beam from 3 MeV to 20 MeV in a distance of around 13 m. A FFDD lattice structure is selected to provide strong transverse focusing, where each drift tube includes one quadrupole magnet. Beam dynamics simulations specified an effective magnet length of 47 mm, maximum field gradient of 47 T/m, and bore aperture of 24 mm. For these specifications, a detailed design of a very thin permanent magnet quadrupole (PMQ) is presented. Four types of PMQ designs have been compared: a 16-segment trapezoidal design in the Halbach configuration, two 16-segment rectangular designs (with and without gaps), and an 8-segment rectangular design. 2D and 3D modeling codes, POISSON and CST Studio suite are used for the design studies. The good field region is calculated based on field gradient deviation in the transverse plane and integral field homogeneity. The very low aspect ratio of these PMQs leads to edge effects, thereby reducing the central field strength. The 3D simulations are used to study these edge effects. (author)

  16. The low-field permanent magnet electrostatic plasma lens

    International Nuclear Information System (INIS)

    Goncharov, A.; Gorshkov, V.; Maslov, V.; Zadorozhny, V.; Brown, I.

    2004-01-01

    We describe the status of ongoing research and development of the electrostatic plasma lens as used for the manipulation of high current broad beams of heavy ions of moderate energy. In some collaborative work at Lawrence Berkeley National Laboratory the lens was used to good effect for carrying out high dose ion implantation processing. In the process of this work a very narrow range of low magnetic field was found for which the ion-optical characteristics of the lens improved markedly. Subsequent theoretical analysis and computer modeling has led to an understanding of this phenomenon. These serendipitous results open up some attractive possibilities for the development of a new compact and low cost plasma lens based on permanent magnets rather than on current-driven field coils surrounding the lens volume. The development of this kind of lens, including both very low noise and minimal spherical aberration effects, may lead to a tool suitable for use in the injection beam lines of high current heavy ion linear accelerators. Here we briefly review the lens fundamentals, some characteristics of focusing heavy ion beams at low magnetic fields, and summarize recent theoretical and experimental developments, with emphasis on the relevance and suitability of the lens for accelerator injection application

  17. Magnetic dipole self-organization of charge carriers in high-temperature superconductors and kinetics of phase transformation

    CERN Document Server

    Voronov, A V; Shuvalov, V V

    2001-01-01

    The phenomenological model, describing the magnetic dipole self-organization of charge carriers (formation of so-called stripe-structures and energy gap in the states spectrum), is designed for interpreting the data on the nonstationary nonlinear spectroscopy of the high-temperature superconductors. It is shown that after fast heating of the superconducting sample the kinetics of the subsequent phase transition depends on the initial temperature T. The destruction of the stripe-structures at low overheating T* < T < T sub m approx = (1.4-1.5)T*, whereby T sub c and T* approx = T sub c are the temperatures of transition into the superconducting state and formation of the stripe-structures occurs slowly (the times above 10 sup - sup 9 s) in spite of practically instantaneous disappearance of the superconductivity

  18. Electron current extraction from a permanent magnet waveguide plasma cathode

    Energy Technology Data Exchange (ETDEWEB)

    Weatherford, B. R.; Foster, J. E. [University of Michigan, Ann Arbor, Michigan 48109 (United States); Kamhawi, H. [NASA Glenn Research Center, Cleveland, Ohio 44135 (United States)

    2011-09-15

    An electron cyclotron resonance plasma produced in a cylindrical waveguide with external permanent magnets was investigated as a possible plasma cathode electron source. The configuration is desirable in that it eliminates the need for a physical antenna inserted into the plasma, the erosion of which limits operating lifetime. Plasma bulk density was found to be overdense in the source. Extraction currents over 4 A were achieved with the device. Measurements of extracted electron currents were similar to calculated currents, which were estimated using Langmuir probe measurements at the plasma cathode orifice and along the length of the external plume. The influence of facility effects and trace ionization in the anode-cathode gap are also discussed.

  19. 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.

  20. Fuzzy Impulsive Control of Permanent Magnet Synchronous Motors

    International Nuclear Information System (INIS)

    Dong, Li; Shi-Long, Wang; Xiao-Hong, Zhang; Dan, Yang; Hui, Wang

    2008-01-01

    The permanent magnet synchronous motors (PMSMs) may experience chaotic behaviours with systemic parameters falling into a certain area or under certain working conditions, which threaten the secure and stable operation of motor-driven. Hence, it is important to study the methods of controlling or suppressing chaos in PMSMs. In this work, the Takagi–Sugeno (T-S) fuzzy impulsive control model for PMSMs is established via the T-S modelling methodology and impulsive technology. Based on the new model, the control conditions of asymptotical stability and exponential stability for PMSMs have been derived by the Lyapunov method. Finally, an illustrated example is also given to show the effectiveness of the obtained results

  1. Experimental Evaluation of a Motor Integrated Permanent Magnet Gear

    DEFF Research Database (Denmark)

    Rasmussen, Peter Omand; Frandsen, Tommy; Jensen, Kasper Køtter

    2011-01-01

    This paper presents test results of a new motor integrated permanent magnet gear and clarifies a path for future optimizations. The prototype, which fabrication also is described, is initially targeting electrical traction for vehicles. Basic measured parameters in form of back-emf, stall torque...... and inductances are all in line with finite element calculations. However very high rotational losses are present in the prototype and these losses are higher than the calculations. Some of the losses are present due to poor aspects in the fabrication of the prototype, while others are identified to be caused...... by a non optimal diameter/length aspect ratio. The torque density is superior, the copper losses is only a fraction of the copper losses in other traction motors. With the proposed aspects to reduce the rotational losses is it believed that the unit has a great potential....

  2. Control of Permanent Magnet Synchronous Generator for large wind turbines

    DEFF Research Database (Denmark)

    Busca, Cristian; Stan, Ana-Irina; Stanciu, Tiberiu

    2010-01-01

    Direct Torque Control (DTC) and Field Oriented Control (FOC) are the most dominant control strategies used in generators for wind turbines. In this paper both control methods were implemented on a Permanent Magnet Synchronous Generator (PMSG). The variable speed wind turbine with full scale power...... converter topology was chosen for design. Parameters from a 2 MW wind turbine were used for system modeling. All the components of the wind turbine system (WTS), except the DC-link and the grid site converter were implemented in MATLAB/Simulink. The pitch controller was used to limit the output power...... produced by the turbine. DTC and FOC strategies, using SVM were used to control the generator rotor speed. The performance of the two control strategies were compared after different tests have been carried out....

  3. Optimization of Multibrid Permanent-Magnet Wind Generator Systems

    DEFF Research Database (Denmark)

    Chen, Zhe; Li, H.; Polinder, H.

    2009-01-01

    and multibrid wind turbine configurations are obtained, and the suitable ranges of gear ratios for different power ratings are investigated. Finally, the detailed comparisons of themost cost-effective multibridPMgenerator system and the optimized direct-drive PM generator system are also presented and discussed....... The comparative results have shown that the multibrid wind turbine concept appears more cost-effective than the direct-drive concept.......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...

  4. Dynamics and Stability of Permanent-Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Ren He

    2017-01-01

    Full Text Available The aim of this article is to explore the dynamic characteristics and stability of the permanent-magnet synchronous motor (PMSM. PMSM equilibrium local stability condition and Hopf  bifurcation condition, pitchfork bifurcation condition, and fold bifurcation condition have been derived by using the Routh-Hurwitz criterion and the bifurcation theory, respectively. Bifurcation curves of the equilibrium with single and double parameters are obtained by continuation method. Numerical simulations not only confirm the theoretical analysis results but also show one kind of codimension-two-bifurcation points of the equilibrium. PMSM, with or without external load, can exhibit rich dynamic behaviors in different parameters regions. It is shown that if unstable equilibrium appears in the parameters regions, the PMSM may not be able to work stably. To ensure the PMSMs work stably, the inherent parameters should be designed in the region which has only one stable equilibrium.

  5. 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...... collecting vibration and current data in order to cross-reference the indications from the two monitoring techniques. It is found that electric signature analysis shows no response even when two hold down bolts are untightened, whereas the analysis results from the vibration data exhibit superior performance....... The vibration-based condition indicators with the best response are the stator slot pass frequency, which can be directly related to the cogging torque in PMGs, and the 4th electric frequency harmonic, whose amplitudes increase due to the overall lower structure damping coefficient under looseness...

  6. Tessellated permanent magnet circuits for flow-through, open gradient separations of weakly magnetic materials

    International Nuclear Information System (INIS)

    Moore, Lee R.; Williams, P. Stephen; Chalmers, Jeffrey J.; Zborowski, Maciej

    2017-01-01

    Emerging microfluidic-based cell assays favor label-free red blood cell (RBC) depletion. Magnetic separation of RBC is possible because of the paramagnetism of deoxygenated hemoglobin but the process is slow for open-gradient field configurations. In order to increase the throughput, periodic arrangements of the unit magnets were considered, consisting of commercially available Nd-Fe-B permanent magnets and soft steel flux return pieces. The magnet design is uniquely suitable for multiplexing by magnet tessellation, here meaning the tiling of the magnet assembly cross-sectional plane by periodic repetition of the magnet and the flow channel shapes. The periodic pattern of magnet magnetizations allows a reduction of the magnetic material per channel with minimal distortion of the field cylindrical symmetry inside the magnet apertures. A number of such magnet patterns are investigated for separator performance, size and economy with the goal of designing an open-gradient magnetic separator capable of reducing the RBC number concentration a hundred-fold in 1 mL whole blood per hour. - Highlights: • Simple geometry of commercial, off-the-shelf NdFeB magnet blocks is amenable to generate high fields and open gradients. • Periodic pattern of permanent magnet blocks (tessellation) reduces the number of blocks per separation channel and improves the efficiency of separator design. • Split-flow lateral transport thin (SPLITT) fractionation model predicts 100-fold reduction of red blood cells from 1 mL whole blood sample in 1 h, suitable for laboratory medicine applications.

  7. Tessellated permanent magnet circuits for flow-through, open gradient separations of weakly magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Lee R. [Department of Biomedical Engineering, Cleveland Clinic, 9500 Euclid Ave., Cleveland OH 44195 (United States); Williams, P. Stephen [Cambrian Technologies, Inc., Cleveland, OH (United States); Chalmers, Jeffrey J. [William G. Lowrie Department of Chemical and Biomedical Engineering, The Ohio State University, Columbus 151 W. Woodruff Avenue, OH 43210 (United States); Zborowski, Maciej, E-mail: zborowm@ccf.org [Department of Biomedical Engineering, Cleveland Clinic, 9500 Euclid Ave., Cleveland OH 44195 (United States)

    2017-04-01

    Emerging microfluidic-based cell assays favor label-free red blood cell (RBC) depletion. Magnetic separation of RBC is possible because of the paramagnetism of deoxygenated hemoglobin but the process is slow for open-gradient field configurations. In order to increase the throughput, periodic arrangements of the unit magnets were considered, consisting of commercially available Nd-Fe-B permanent magnets and soft steel flux return pieces. The magnet design is uniquely suitable for multiplexing by magnet tessellation, here meaning the tiling of the magnet assembly cross-sectional plane by periodic repetition of the magnet and the flow channel shapes. The periodic pattern of magnet magnetizations allows a reduction of the magnetic material per channel with minimal distortion of the field cylindrical symmetry inside the magnet apertures. A number of such magnet patterns are investigated for separator performance, size and economy with the goal of designing an open-gradient magnetic separator capable of reducing the RBC number concentration a hundred-fold in 1 mL whole blood per hour. - Highlights: • Simple geometry of commercial, off-the-shelf NdFeB magnet blocks is amenable to generate high fields and open gradients. • Periodic pattern of permanent magnet blocks (tessellation) reduces the number of blocks per separation channel and improves the efficiency of separator design. • Split-flow lateral transport thin (SPLITT) fractionation model predicts 100-fold reduction of red blood cells from 1 mL whole blood sample in 1 h, suitable for laboratory medicine applications.

  8. Force prediction in permanent magnet flat linear motors (abstract)

    International Nuclear Information System (INIS)

    Eastham, J.F.; Akmese, R.

    1991-01-01

    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 degree 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

  9. A National Collaboratory to Advance the Science of High Temperature Plasma Physics for Magnetic Fusion

    International Nuclear Information System (INIS)

    Schissel, D.P.; Abla, G.; Burruss, J.R.; Feibush, E.; Fredian, T.W.; Goode, M.M.; Greenwald, M.J.; Keahey, K.; Leggett, T.; Li, K.; McCune, D.C.; Papka, M.E.; Randerson, L.; Sanderson, A.; Stillerman, J.; Thompson, M.R.; Uram, T.; Wallace, G.

    2006-01-01

    This report summarizes the work 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 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 a collaboration itself uniting fusion scientists from General Atomics, MIT, and PPPL and computer scientists from ANL, LBNL, 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. Developing a reliable energy system that is economically and environmentally sustainable is the long-term goal of Fusion Energy Science (FES) research. In the U.S., FES experimental research is centered at three large facilities with a replacement value of over $1B. As these experiments have increased in size and complexity, there has been a concurrent growth in the number and importance of collaborations among large groups at the experimental sites and smaller groups located nationwide. Teaming with the experimental community is a theoretical and simulation community whose efforts range from applied analysis of experimental data to fundamental theory (e.g., realistic nonlinear 3D plasma models) that run on massively parallel computers. Looking toward the future, the large-scale experiments needed for FES research are staffed by correspondingly large, globally dispersed teams. The fusion program will be increasingly oriented toward the International Thermonuclear Experimental Reactor (ITER) where even now, a decade before operation begins, a large

  10. 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.

  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. A chiral-based magnetic memory device without a permanent magnet.

    Science.gov (United States)

    Ben Dor, Oren; Yochelis, Shira; Mathew, Shinto P; Naaman, Ron; Paltiel, Yossi

    2013-01-01

    Several technologies are currently in use for computer memory devices. However, there is a need for a universal memory device that has high density, high speed and low power requirements. To this end, various types of magnetic-based technologies with a permanent magnet have been proposed. Recent charge-transfer studies indicate that chiral molecules act as an efficient spin filter. Here we utilize this effect to achieve a proof of concept for a new type of chiral-based magnetic-based Si-compatible universal memory device without a permanent magnet. More specifically, we use spin-selective charge transfer through a self-assembled monolayer of polyalanine to magnetize a Ni layer. This magnitude of magnetization corresponds to applying an external magnetic field of 0.4 T to the Ni layer. The readout is achieved using low currents. The presented technology has the potential to overcome the limitations of other magnetic-based memory technologies to allow fabricating inexpensive, high-density universal memory-on-chip devices.

  13. Torque characteristics of double-stator permanent magnet synchronous machines

    Directory of Open Access Journals (Sweden)

    Awah Chukwuemeka Chijioke

    2017-12-01

    Full Text Available The torque profile of a double-stator permanent magnet (PM synchronous machine of 90 mm stator diameter having different rotor pole numbers as well as dual excitation is investigated in this paper. The analysis includes a comparative study of the machine’s torque and power-speed curves, static torque and inductance characteristics, losses and unbalanced magnetic force. The most promising flux-weakening potential is revealed in 13- and 7-rotor pole machines. Moreover, the machines having different rotor/stator (Nr/Ns pole combinations of the form Nr = Ns ± 1 have balanced and symmetric static torque waveforms variation with the rotor position in contrast to the machines having Nr = Ns ± 2. Further, the inductance results of the analyzed machines reveal that the machines with odd rotor pole numbers have better fault-tolerant capability than their even rotor pole equivalents. A prototype of the developed double-stator machine having a 13-pole rotor is manufactured and tested for verification.

  14. High speed subfractional HP-motor with permanent magnets

    International Nuclear Information System (INIS)

    Hanitsch, R.; Frenzel, B.

    1998-01-01

    During the last years an increasing demand for small permanent magnet motors can be detected, especially in the fields of medical applications. For heart assist devices there is the request to have small high speed devices operating at low voltage supply with almost no overtemperature. The design of a special hollow shaft motor for the speed range of 15000..25000 rpm and a torque of 4 to 8 mNm will be outlined. The low noise requirements and the high efficiency request lead to a design with an airgap winding. A thermal analysis is also done in order to meet the conditions given by the medical specialists. The features of the prototype will be presented and also the sensorless control strategy will be outlined. Measured and calculated data show good agreement. Focus will be on the magnetic circuit and the thermal behaviour and not on the control aspects of the motor. Specific parameters demonstrate the good quality of the drive system. (orig.)

  15. 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...

  16. 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...

  17. 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.

  18. Development of a hybrid bearing using permanent magnets and piezoelectric actuators

    International Nuclear Information System (INIS)

    Park, Jung-Ho; Ham, Young-Bog; Yun, So-Nam; Lee, Hu-Seung

    2010-01-01

    In this study, a hybrid magnetic bearing with permanent magnets and piezoelectric actuators is investigated. First, in this study, a novel concept in which piezoelectric actuators are used to compensate for low stiffness and damping resulting from the unstable characteristics of a passive magnetic bearing using only permanent magnets is proposed. Secondly, the permanent magnets are optimally arranged through an electromagnetic field analysis. Then, the driving amplifier unit and a prototype radial bearing using the proposed concept are fabricated. Finally, basic characteristics, such as the results of an impact test and a rotational runout test with constant speed are investigated and discussed, and experiments using PID control method are conducted.

  19. Effect of axial magnetic field on a 2.45 GHz permanent magnet ECR ion source.

    Science.gov (United States)

    Nakamura, T; Wada, H; Asaji, T; Furuse, M

    2016-02-01

    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(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.

  20. 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.