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Magnews Spring 2009 1

Magnews is published by the UK Magnetics Society, Grove Business Centre, Grove Technology Park, Wantage, Oxon OX12 9FA

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The international publication of the UK Magnetics Society

Spring 2009 magnews

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Contents From the chairman

The Editor accepts no responsbility or liability in any way whatsoever for statements made or opinions expressed in Magnews

From the Chairman 3UKMAG members news 4,10Report on UKMAG seminar, Noise in Electrical Machines, 7

at Cardiff University, 4 February 09 UKMAG management committee 9 Company profile new member: Curie Industrial 10 Co Ltd, Taiwan Advertising in Magnews 10UKMAG members’ training courses 10 Report on UKMAG seminar, Advanced Functional 12 Materials, at the National Physical Laboratory, Teddington, 19 March 09Report on UKMAG seminar, More Electric Aircraft, at 15

University of Bristol, 2 April 09 QinetiQ wins demonstrator programme 19 Cobham rebrands three businesses 19Low Noise Power Transformers - more energy in large 20

cities with less noisePreparation, Purification and Crystal Growth of Metallic 24

Elements, Alloys, Compounds and Oxides Room Temperature Proximity Effect Across the 26 Fe/GaMnAs InterfaceLake Shore and NASA’s FORCAST Instrument on 28 the SOFIA airbourne telescope Student Bursary Scheme/Dennis Hadfield Memorial Prize 29 Development of the rare earth magnet industry [follow 31

on from Winter 08 issue]Drive Train Solutions for Solar Powered UAVs 35Suggestions for future UKMAG seminars UKMAG forthcoming seminars for 2009 37

28 April 09, • Cutting Costs by Optimised Use of Materials, at TRW Conekt, Solihull24 June 09, • Superconductivity Applications, at University of Birmingham12-13 Oct 09, • Advanced Magnetic Materials and their Applications, at Hanau, Germany [hosted, co-sponsored by Vacuumschmelze GmbH, Germany]Nov 09, • Distributed Generation, at Areva T&D Technology Centre, StaffordNov 09, • Instruments: Measurements and StandardsDec 09, 23rd Ewing Event, London•

Dates for your diary 38First invitation to bid for Compumag 2013 38

Front page graphic: QinetiQ’s Zephyr UAV during its world record-setting longest duration unmanned flight, incorporating direct drive technology from University of Newcastle (see page 35)

Welcome to the spring edition of Magnews. It seems only a short time ago that I wrote my first ‘From the chairman’

and here I am penning my last. The Society has undergone a number of significant changes over the past few years, of which I am proud to have been a contributor to. It’s very easy to overlook the impact of steady improvements made over a long period of time, especially when those improvements are the result of team efforts, with small but significant contributions coming from every member of the group. However, sitting back and taking stock has helped me to recall some of the considerable advances the Society has made, all of which have been achieved by the members of the committee, both past and present, who give up their personal time to pursue the main remit of our Society, of forwarding the knowledge, understanding and interaction between our small, but global, magnetics community.

Over the last few years, your committee team have restyled and reinvigorated the magazine you’re presently holding. They’ve established and continued to develop links with other Societies and companies both in the UK and continental Europe. They’ve streamlined and improved the mechanism by which we develop and organise seminars.

These achievements, along with many others, have steadily improved not only the value of membership for the Society’s members, but have also begun the process of safeguarding the future potential of the Society. I was extremely pleased to announce at our recent AGM our second year of sustainable financial growth. Although our surplus was small, it was a marked improvement on previous years and is wholly attributable to the hard work, innovation and dedication of both my colleagues on the committee and our wonderful Secretariat, ably helmed by Jane and Margaret.

As I mentioned, one of the key areas we’ve looked to improve upon is in the seminars we offer you, the members. This year has been no different and so far we have held successful and well-received seminars covering Noise in Electrical Machines at Cardiff University, Advanced Functional Materials at NPL in Teddington and More Electric Aircraft at the University of Bristol. Late April will see a new seminar with a very topical theme, when TRW Conekt in Solihull hosts Cutting Costs by Optimised use of Materials. A subject, I’m sure, very close to the heart of any manufacturing or development team be they industrial or academic.

Later this year, the Society will be continuing its successful series of mainland Europe based co-sponsored events, which we started back in 2007 with Höganäs in Sweden. This new and exciting joint venture is with Vacuumschmelze GmbH in Germany. The event, entitled Advanced Magnetic Materials and their Applications, will be held in October, over two days, in Hanau, near Frankfurt. Another area of value improvement which I am pleased to announce is that the Society’s student bursaries, which aim to support postgraduates presenting at international conferences, has now been increased to £250 per student (see page 29 for further details).

Well, that only leaves me to say thank you for your support over the past two years and to leave you with a heartfelt request that you continue to support your Magnetics Society, so that it can continue to support you.Dr Chris Maddison, Cummins Generator Technologies


UKMAG members’ news Geoff Bartington obituaryGeoff Bartington, the Technical Director of Bartington

Instruments Ltd, died on 13 December 2008 aged 60. Trained as an electronics engineer specialising in telecommunications, he became interested in geophysics, geomagnetism and archaeology whilst working at Littlemore Scientific Engineering in Oxford. He originated the idea of a magnetic susceptibility meter with a range of sensors for different applications for the emerging discipline of environmental magnetism. When his employer declined to take up this idea commercially he continued development, with encouragement from Professor Oldfield of Liverpool University, at home in his spare time. A prime innovation was the use of a dual frequency laboratory sensor to allow the study of magnetic viscosity phenomena in the finer fractions of sediments and soils.

In 1985 Geoff and Tessa Bartington (now Tessa Evans) formed Bartington Instruments Ltd. The magnetic susceptibility system was soon followed by further products. When a suitable fluxgate sensor for an instrument to measure the declination and inclination of the geomagnetic field was not available, Geoff designed and built his own. This was typical of his approach.

Geoff went on to design a family of world-leading single and three-axis fluxgate magnetometers. His genius for invention coupled with his commercial foresight allowed his designs to be used for a wide range of applications and remain viable over an extended period.

One of his last designs is the hugely successful Grad601 magnetic gradiometer for archaeological prospection.

Geoff had several papers and patents to his credit but the need for commercial confidentiality prevented him from publishing his most important work. He was a regular lecturer at the National Parks summer courses on archaeology in the USA. His untimely death prevented him from taking up a Visiting Fellowship extended to him by Oxford University. By his inventive genius and understanding the needs of researchers, Geoff made a unique contribution to environmental magnetics and archaeology. The instruments he designed are to be found in all the major universities and every corner of the world. He leaves a legacy of a thriving company with a unique range of products. Bartington Instruments Ltd, tel: +44 (0)1993 706565, www.bartington.com

Electron Energy Corporation (EEC), a leading US producer of rare-earth magnets, has been awarded a $750,000 Small

Business Technology Transfer Research (STTR) contract by the Department of Energy (DOE) Office of Science, Argonne, IL. The announcement was made by Michael H Walmer, EEC President.The Phase II research contract (DOE Grant Award No DE-FG02-07ER86308), which runs from August 2008 through August 2009, is for the development of high performance magnets and magnet technologies for advanced motors used in hybrid electric vehicles (HEVs). Phase II research will centre on innovating a new class of permanent magnets with high magnetic performance, high resistivity, superior thermal stability and low cost. EEC successfully completed Phase I research in July 2008.

Dr Jinfang Liu, an internationally-recognised expert on rare earth magnet materials and EEC Vice President of Technology and Engineering, will serve as the principal investigator and director of the research project. “Our goal is to design and develop nanocomposite magnets that can reduce eddy current losses and withstand high temperatures to improve the performance of electric motors for plug-in hybrid cars as well as conventional motors and generator applications,” Liu said. EEC will collaborate on the research and receive support from the University of Delaware under the leadership of Dr George Hadjipanayis, the Richard B Murrey Professor of Physics and Chair of the Department of Physics & Astronomy.

“Our research will be critical for the development of plug-in hybrid motors that are more efficient, affordable and pollution-free,” said Walmer. “We are pleased to work with the DOE and are confident that the technologies we develop will help to decrease US dependence on foreign oil. Ultimately, this program aims to improve performance and significantly reduce the cost of vehicles powered by forms of energy other than those derived from fossil fuel.”

Liu said that eddy current loss is a major consideration in some motor designs. In order to reduce the eddy current losses in motors caused by permanent magnets, designers typically use segmented magnets rather than single-piece magnets, which reduces the eddy current losses, but also increases the manufacturing cost.

Key components of Phase II research include: improving the magnetic performance of high temperature magnets by compositional and process related modifications, as well as developing new hybrid magnets; reducing eddy current losses by increasing the electrical resistivity in new composite magnets which contain dielectric constituents; and decreasing costs by using less expensive raw materials and lower cost process procedures.

Peter Dent, EEC VP of Business Development, said EEC proposes to develop a new class of Sm-Co permanent magnets with an electrical resistivity five to 10 times higher than those of commercially available magnets and deliver superior magnetic performance. These high resistivity magnets, which are able to operate at temperatures above 200°C, will significantly reduce eddy current losses and keep the cost low for motor/generators systems.

EEC is the only company in the world to produce ultra-high temperature SmCo magnets capable of operating in the 350 to 550°C range and has broad US patent protection for this technology. Competitive magnet technologies have energy products several times lower than EEC high temperature magnets. Since 1996, EEC has been granted 18 STTR or SBIR Phase I and Phase II programs, which resulted in three patents,

Electron Energy Corporation wins contract


as well as over 20 papers published in professional journals.For more information about Electron Energy Corporation’s high-temperature magnet capabilities, visit www.electroenergy.com. Our staff of engineering specialists is available for free technical consultations and will travel to on-site meetings.

About Electron Energy CorporationElectron Energy Corporation (EEC) offers unmatched expertise in rare earth magnets, assemblies and systems. Founded in 1970, EEC is a US supplier that develops and produces custom Samarium Cobalt (SmCo) and Neodymium-Iron-Boron (NdFeB) sintered permanent magnets, assemblies and systems. EEC is dedicated to improving rare earth magnet performance to meet the most technically demanding applications in aerospace, military, medical, electronics, and motion control markets. As world-renowned experts in material sciences, testing and 2-D/3-D Finite Element Analysis, our vertically integrated operation provides you with the full range of services to meet your magnetic needs. Visit www.electronenergy.com.About the HEV IndustryTotal HEV demand for the world will be 4.5 million units by 2013. In 2003, there were already 94,000 units and in 2008 the number grew to 770,000. HEV growth is accelerating because of rising energy costs and increased emissions regulations. By 2013, HEVs are expected to represent over 6% of world light vehicle demand. Primary markets are expected to be within the Triad countries (ie, the US, Western Europe and Japan), although there will be much larger gains for HEVs in the US and Japan. In Europe, where car diesel demand already exceeds 40% of the total passenger car market, HEV growth is projected to be much slower. China may also be another strong market.

UK Defence contract for Bartington InstrumentsBartington Instruments Ltd has received an order for the supply

of its new DAS1 Data Acquisition System, with associated fluxgate magnetometers, from a UK defence company. The order, worth more than £85K, will form the basis of a magnetic signature range facility. In addition to the DAS1-20, the system will include fifteen of the latest Mag-03RC Three-axis Marine Magnetometers and a depth/tilt sensor.

The DAS1 is a versatile system, for recording and analysing data from a large number of magnetometers and other sensors. Comprising both analog signal conditioning and digital processing, its modular construction can be expanded to support up to 70 three-axis magnetometers. It will operate with all Bartington Instruments Mag-03 sensors, including the Mag-03RC Marine version.

The Mag-03RC is a recently introduced submersible magnetometer, intended for long-duration underwater applications, like magnetic ranges. High reliability, low noise and the ability to operate with long cables are other key features of the sensor. The Mag-03RC is ideal for fixed installations, where the magnetic field sensor is held stationary. For mobile applications, like magnetic anomaly detection and pipe & cable location, the Bartington Grad-03-500M Fluxgate Gradiometer will provide a better solution.

Bartington Instruments Ltd (UK) designs and manufactures a wide range of magnetic measuring instruments used in defence, geophysics and underwater applications. This includes single and three-axis fluxgate sensors, fluxgate gradiometers and magnetic susceptibility measuring equipment. Custom magnetometer design and manufacture is also available. For further information visit www.bartington.com or email [email protected]


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UKMAG seminar Noise in Electrical Machines, at Cardiff University, 4 February 2009

Speakers from left: Dr Chris Riley, Jan Anger, Dr Philip Anderson, Dr Peter Hamberger, Dr Piotr Klimczyk, Keith Jeknins, Dr Krzysztof Wejrzancwski, Dr Tom Hilgert,

Dr Nigel Jakeman, Prof Qiang Zhu

The delegates for the Noise in Electrical Machines seminar braved

wintry conditions to make their way in large numbers to Cardiff University. Fifty seven attendees, representing 32 different organisations in 10 different countries, provided sufficient evidence that designing and building electrical machines with low acoustic noise emissions is of paramount importance in today’s society.

The morning session focused on noise in transformers. The first speaker, Keith Jenkins of Cogent Power Limited, presented Aspects of Noise Associated with GO Electrical Steels in Transformer Applications. The sources of noise in transformers, magnetostrictive vibrations of the core and magneto-motive vibrations in the core and windings, and methods for reducing them, both by absorbing enclosures and reduction at source, were introduced setting the scene for the remainder of the session. The noise generated in various model step lap transformer core configurations was then presented and it was shown that five or seven step lap cores with 4mm or 6mm step overlap tended to give lower noise than cores with a three step lap configuration or those with a smaller overlap. The importance of understanding the stress sensitivity of magnetostriction was explained together with the beneficial effects of tension coatings applied to the steel. Finally, the difficulty of estimating transformer noise from magnetostriction data was discussed with methods of calculation incorporating weighted summations of the harmonics of magnetostriction being popular amongst current researchers.

Continuing the theme of magnetostriction measurement the next presenter, Piotr Klimczyk of the Wolfson Centre for Magnetics at Cardiff University, gave a presentation entitled Stress Sensitivity of Magnetostriction in Grain Oriented Steels. Following a description of the complex domain patterns induced by the application of compressive stress to the rolling direction of grain oriented steels, and the rapid increase in magnetostriction they generate, a new system for the measurement of magnetostriction under applied stress was introduced.The system, using a pneumatic cylinder to apply +- 10MPa stress and accelerometers for the measurement of magnetostriction, was shown to be rapid, repeatable and flexible giving designers all the information about the stress sensitivity

of magnetostriction (and several other magnetic parameters) which could be required. Some of the first results from the system were shown including an interesting correlation between strip gauge and magnetostriction under compressive stress.

Jan Anger of ABB Power Transformers gave the next presentation on Noise in Power Transformers – Models for Generation, Transmission and Propagation. A-weighted magnetostriction values were shown to be

higher in conventional grain oriented steel than highly oriented Hi-B material which was replicated in the noise performance of cores made from the same materials.The magnetostriction measurements have been incorporated into finite element models of transformer cores so that the mechanical excitation of the core can be simulated with reasonable accuracy. It was explained that prediction of no load vibrations of the core is only the first step in understanding the noise emissions with transmission to the tank via mountings and fluid together with resonances in the tank and its sound radiation properties being of equal importance.

The final presentation of the morning session was Low Noise Power Transformers – More Energy in Large Cities with Less Noise by Dr Peter Hamburger of Siemens Transformers

Austria (see page 20 for Dr Hamberger’s presentation). As well as the no-load noise discussed previously, we were also introduced to load current noise, generated by Lorentz forces in the windings, via a numerical model used to simulate resonant modes in typical configurations. No load noise calculated by both A-weighted magnetostriction velocity and acceleration values (stress free) were shown to be significantly different to each other and in both cases gave a much smaller noise difference between cores made from two different

materials than measurements. The load current noise, on the other hand, showed good correlation between simulation and measurements. The simulations were used to demonstrate the importance of the oil in coupling the vibrations of windings and how the oil temperature could have a great effect on the vibration pattern and amplitude. Following an example of a modal analysis on a test tank, Dr Hamberger concluded with the steps utilised by Siemens in a low noise design through minimising exciting forces in the windings, avoidance of resonance in core and windings and finally by the implementation of additional sound panels and points identified as having high tank vibrations.

Lunch gave all of the delegates opportunity to network and further discuss the mornings presentations with


UKMAG seminar Noise in Electrical Machines contd...

the speakers being in particularly high demand. A tour of the laboratories of the Wolfson Centre for Magnetics followed lunch before the afternoon’s programme which concentrated on noise in rotating machines.

The first paper of the afternoon session on Contribution of Magnetostriction to the Vibrations of Electrical Machines: Measurement, Modelling and Calculation was given by Dr Tom Hilgert of Ghent University, Belgium, in which he presented a new method for calculating the vibrations of magnetic cores due to magnetostriction and magnetic forces. Tom first introduced the topic with some examples of typical devices which suffer from magnetic noise, and then presented us with some background information on the two components of magnetic noise, namely magnetic forces and magnetostriction. Whilst magnetic forces are well known and can be calculated readily using analytical expressions or finite element analysis, magnetostriction which is a consequence of force interactions between magnetic dipoles in the magnetic domains of ferromagnetic materials is less well known and cannot be calculated this way. Therefore to include magnetostriction in calculations, magnetostriction models have to be based on measurements. The new magnetostriction model presented by Tom was based on an artificial neural network, in which the network was trained to produce the correct results using measurements of magnetostriction under different magnetisation conditions including the effects of hysteresis. Tom went on to describe the method in more detail, showing the test rig used to obtain the measurements, and finally an example analysis on a two pole and four pole 3phase induction motor, with some interesting results.

The second paper of the afternoon, Identification and Correction of Acoustic Noise in Axial Flux Machines, was given by Dr Nigel Jakeman of GenDrive Ltd. Unlike most of the other papers presented, this paper described the very interesting problem of acoustic noise in Axial Flux Machines, which occurs purely due to the fact that the disk-like rotor structure has an aspect ratio very similar to a loud speaker and consequently any natural frequencies causing a disturbance in the structure have the potential to transmit high levels of acoustic energy and completely deafen anyone standing nearby! This was a problem encountered with dramatic effect during the design of a 12 pole, 15kW, TORUS generator with a rotor diameter of 280mm, where a 1.72kHz component of noise at 106dB was recorded under relatively low levels of load. This was in contrast to its

predecessor 40kW design which had a 400mm rotor diameter and yet had no noise issues. To overcome the problem, an examination of the rotor mechanical response to an excitation force at the same frequency of the acoustic output was carried out using accelerometers. It was determined that at the natural frequency of the acoustic output the rotor structure produced a mode of vibration that resembled the action of an umbrella opening and closing. Knowing the relationship of the frequency to the mass and stiffness of the rotor, the mechanical structure of the rotor was able to be modified in such a way to force this mode of resonance away from the operating range speed range. Following this example, Nigel showed how a combination of finite element analysis and frequency diagrams could be used to identify the mechanisms that could potentially cause similar axial modes of vibration and thus understand how to prevent the problem occurring again in future re-scaled designs.

After the afternoon tea break, Professor Qiang Zhu, head of the University of Sheffield Machines and Drives Group, gave an in-depth presentation on Noise and Vibration in Fractional Slot Permanent Magnet Brushless Machines. Whilst fractional slot PM machines have many advantages over conventional PM machines, one major disadvantage is that they exhibit low mode order of vibrations and consequently higher acoustic noise. After giving a brief introduction, Qiang went on to discuss the main contributing factors. Alternating radial magnetic forces can occur in the stator tooth tips of all PM machines as the rotor magnets pass in front of each tooth tip and this pulsating force gives rise to vibration. However, Qiang showed, with the aid of extensive finite element analysis, how this vibration is significantly influenced and can be almost eliminated by appropriate choice of the slot/pole combination in

the design. Qiang continued to discuss unbalanced magnetic force (UMF) which is well known to occur in any electrical machine if rotor eccentricity exists. However, Qiang was able to show that even without rotor eccentricity, some fractional-slot PM machines may exhibit UMF’s due to diametrically asymmetric disposition of the stator slots and coils and this can result in excessive acoustic noise and vibration. In addition to radial and UMF’s torque ripples also exist in PM machines due to imperfect back-emf waveforms, PWM commutation and cogging torque etc. Direct Torque Control (DTC) is a method of controlling the motor flux linkages and torque by optimising the inverter switching. Qiang concluded his presentation by demonstrating how DTC PM brushless drives can be used to minimise the effects of torque ripple and cogging torque on the acoustic noise and vibration.

The final presentation of the day, Reducing Acoustic Noise on Reciprocating Engines by Intelligent Control of Electrical Machines, was given by Dr Krzysztof Wejrzanowski of Cummins Generator Technologies. This paper followed the theme of the paper from Professor Qiang Zhu’s in that here a method for vibration cancellation in generator sets by intelligent control of the electrical


machine was presented using a method called Active Torque Cancellation (ATC). Cummins currently produce generator sets for about 80% of the Recreation Vehicle (RV) Market. Low acoustic noise is a key requirement which is achieved simply by reducing the speed of the reciprocating engine. However, the engines used in the gensets tend to have very high torque ripples which in turn create very high engine vibrations at low engine speeds (1400rpm). ATC is a method by which this torque ripple is reduced by applying opposing torques to these ripples through intelligent engine

control. Very simply, ACT is achieved by replacing the standard diode rectifier in the generator AC-DC Converter with an active rectifier with control algorithm’s based on d-q axis current regulators. The active rectifier regulates the DC link voltage and at the same time creates the cancellation torque profile. Critical to this method is selecting the correct cancellation torque profile and Krzys discussed the work carried out by Cummins to achieve this, taking into account the additional losses that the ATC method incurs. Finally Kryzs presented results on a genset installed

on a two cylinder Kubota engine where a half order ATC torque profile was applied resulting in a big reduction in the half order engine vibration thus validating the technique.Dr Chris Riley, Magnet Applications Ltd, and Dr Phil Anderson, Wolfson Centre for Magnetics, Cardiff University

CHAIRMANStuart Eaton, QinetiQ Ltd Farnborough, tel: +44 (0)1252 397409, [email protected] CHAIRMANDr John Cullen, Rolls Royce plc, tel:+44 (0)1332 260033, [email protected] Chris Maddison, Cummins Generator Technologies, tel: +44 (0)1780 686203, [email protected] David Greaves, Hoganas GB Ltd, tel: +44 (0)1732 377726, [email protected] Robin Cornelius, Hirst Magnetic Instruments Ltd, tel: +44 (0)1326 372734, [email protected] Kemp, TRW Conekt, tel: +44 (0)121 627 3590, graham.kemp@ trw.comDr Michael Hall, National Physical Laboratory, tel: +44 (0)20 8943 7189, [email protected]

Dr Glynn Atkinson, University of Newcastle-upon-Tyne, School of Elec, Elec & Computer Eng, tel: +44 (0)191 222 5699, [email protected] Chris Riley, Magnet Applications Ltd, tel: +44 (0)1442 875009, [email protected] Philip Anderson, Wolfson Centre for Magnetics, Cardiff University, tel: +44 (0)29 2087 5936, [email protected] Jonathan Sturgess, AREVA T & D Technology Centre, tel: +44 (0)1785 786519, [email protected] Genhua Pan, University of Plymouth, School of Elec, Comm & Elec Eng, tel: +44 (0)1752 232603, [email protected] Andy Williams, University of Birmingham, Dept of Metallurgy & Materials, tel: +44 (0)121 414 3959, [email protected] Allcock, Cobham Technical Services, tel: +44 (0)1865 370151, [email protected] Nicola Morley, University of Sheffield, Dept of Engineering Materials, tel: +44 (0)117 222 5935, [email protected]

UKMAG management committee [following the AGM on 2 April 09]

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UKMAG members news contd...

Company profile - new UKMAG member

Curie was founded in 1996, and is one of largest professional iron powder cores manufacturer in Taiwan. An overseas

manufacturing mass production lines base was expanded and constructed in China in 1999. The factory acquired ISO-9001 quality assurance certification in 2000.

Curie’s TAF200TM series cores are designed to be thermal Aging Free up to 200o. TAF200TM is a registered Patent Trademark in the US, China and Taiwan. Today, the Curie TAF200TM core is a symbol of quality and reliability for the computer and power electronics industry worldwide.

Curie’s products are recognised and used by domestic companies such as Foxconn, Delta, Asus, Liteon, Mitac, and companies abroad such as Dell, Hp, Intel, Microsoft,TI etc.

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Curie Industrial Co Ltd, Taiwan

New product released by Bartington InstrumentsBartington Instruments has released a new product, the

Mag639, a 3-axis fluxgate magnetometer derived from the Mag-03 sensors range. This new sensor is designed for TDEM (Time-Domain Electro-Magnetics) operation and provides an increased response to highly conductive and shallow targets. The sensor can also be used in other EM methods such as MT (Magnetotellurics).

The new sensor offers a wider bandwidth than the Mag-03 range (up to 12kHz), whilst the noise level is below 20pTrms/√Hz @ 1Hz. It has a measuring range of 100µT full range. The enclosure of the sensor is made of non-electrically conductive material, preventing the creation of eddy currents at its surface, when using the instrument during EM (electro-magnetics) operations. Further, the shielded cable provided with the sensor prevents any interference in the signal. The environmental characteristics of the sensor make it suitable for use in the field.

Bartington Instruments Ltd (UK) designs and manufactures a wide range of magnetic measuring instruments used in defence, geophysics and underwater applications. This includes single and three-axis fluxgate sensors, fluxgate gradiometers and magnetic susceptibility measuring equipment. Custom magnetometer design and manufacture is also available. For further information or technical enquiries, please contact Ludovic Letourneur, Technical Sales Executive, tel: +44 (0)1993 706565, email: [email protected], www.bartington.com

UKMAG seminar papers UKMAG seminar papers are available to members free of charge; non-members may purchase sets of papers after the event has taken place. For further details contact: [email protected]

If you have any comments on issues relating to magnetics in general, or any articles contained in Magnews, the Editor will be pleased to hear from you.

UKMAG members’ training courses and workshopsMembers: please let us have details of your training courses and workshops for free inclusion in Magnews. See copy deadlines for Magnews, above, or contact [email protected]

Laboratorio Elettrofisico/ Walker LDJ Scientific at CWIEME Berlin 2009Laboratorio Elettrofisico/Walker LDJ Scientific announce

that they will be participating at CWIEME Berlin 2009 on 5-7 May 2009, in Berlin, Germany. Dr Luca Zanon and Eng Andrea Del Prete from Laboratorio Elettrofisico Engineering Italy, will be available to meet customers at their stand in Booth 1035, Hall 1.1. Laboratorio Elettrofisico, as a major expert in magnetising and magnetic measuring techniques, will be at your disposal to discuss problems in magnetic applications. The Coil Winding Expo is a great occasion to meet customers, understand their needs and discuss solutions.For further details contact Laboratorio Elettrofisico Engineering Srl, [email protected],www.laboratorio.elettrofisico.com

Why not advertise in Magnews? Magnews’s ever-growing, comprehensive and well targeted mailing list reaches magnetics specialists, including manufacturers, distributors and users, in industry, academia and government, worldwide, covering UK: 40%, Europe: 30% and North America/Japan/China/other: 30%. Magnews is the only publication targeted to such groups. Graphics/artwork: High quality eps/tiff/jpeg, minimum of 300 dpi, preferably higher, high resolution print-ready pdf (Illustrator/Freehand/Photoshop/QuarkXpress)2009 copy deadlines:Spring 1 March (published early April)Summer 1 June (published early July)Autumn 1 September (published early Oct) Winter 15 November (published mid-January)Please contact [email protected] for advertising rates

UK Magnetics Society Student Bursary SchemeThe Society is pleased to announce that its Student Bursaries have increased from £100 to £250. These bursaries are to assist postgraduate students of member organisations to attend international conferences - see page 29 for further details.


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5 & 10 Thorney Leys Business Park

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UKMAG seminar Advanced Functional Materials, at the National Physical Laboratory, on 19 March 2009

A one-day seminar, Advanced Functional Materials, was held

on Thursday, 19 March 2009, at NPL (National Physical Laboratory), Teddington. The objective of the seminar was to bring together experts from a number of disciplines in advanced functional materials to present the latest developments in their respective fields.

Ten speakers made their presentations on topics of magnetic semiconductors, magneto-plasmonics, magnetic tunnel junctions, magnetic nanowires and multiferroic materials and devices.

The morning session was chaired by Dr Michael Hall of NPL. After a brief introduction of the NPL meeting venue, the first presentation was given by Dr Francesco Maccherozzi of Laboratorio Nazionale TASC, Italy. Dr Maccherozzi talked about his recent work on the successful measurement of room temperature ferromagnetic proximity effect at the Fe/(GAMn)As interface by XMCD technique, which was published in Physical Review Letters (PRL 101, 267201 (2008)). Since its discovery in 1996, the (Ga,Mn)As DMS material has been a subject of intense research for a potential semiconductor spintronic material.

However, despite more than 10 years’ intensive efforts worldwide, the highest Curie temperature obtained so far is still below 200K, which prevents its use for practical devices. Dr Maccherozzi’s recent work has shown that a thin Fe layer deposited atop of Fe/(Ga,Mn)As could induce a room temperature ferromagnetism in a depth of up to 8 nm into the DMS material via the

ferromagnetic proximity effect. This has been perceived by many in the community as a ground-breaking development in the field and may open up huge opportunities for exploration of new spintronic devices based on this effect if it is further conformed.

The second presentation in the morning, given by Dr Raphael Matelon of University of Exeter, School of Engineering, Computer Science and Mathematics, was about functional magneto-plasmonics.Dr Matelon started his talk with a brief introduction of plasmons and magneto-plasmonic effect. Plasmons are the quasiparticles resulting from the quantizations of plasma oscillations just as photons are quantizations of light waves. However, unlike photons, plasmons are influenced by the presence of a magnetic field during propagation.

Speakers from left: Prof Genhua Pan, Dr Michael Hall, Dr Robert Quarshie, Dr Neil Mathur, Dr Eugene Melikhov, Prof Mike Gibbs, Dr Francesco Maccherozi, Dr Anna-Karis Axelsson, Dr Raphael Matelon, Dr Roger Ward

The speakers are standing in front of the gates from the original NPL entrance off Queens Road which were refurbished and moved to their current location in 2008. These gates were first erected in 1925 to mark the expansion of NPL and the ‘new’ NPL entrance was formally opened on 23 June 1925 in a ceremony involving Lord Rayleigh.

Magneto-plasmonics is a new field to study the light frequency shift of plasmons under a DC magnetic field. This offers, in principle, an as yet unexplored means of shifting or modulating the frequency of optical radiation with the possibility of new devices and technologies. Dr Matelon talked about his recent experimental results on a ferromagnetic surface in the presence of

an applied DC magnetic field, and discussed the technical challenges and limitations for the practical realisation of device applications based on such an effect.

This was followed by two presentations on MTJs (magnetic tunnel junctions) given by Dr Roger Ward of Oxford University and Professor Genhua Pan of University of Plymouth, r e s p e c t i v e l y . D r Ward’s talk focused on the expitaxial MTJs grown by MBE (molecular beam epitaxy). He began his talk with a review of the theoretical progress of coherent tunnelling in fully expitaxial MTJs with an MgO tunnel barrier and the technological drivers in the field. He then presented detailed

experimental results obtained by the group using the Oxford MBE facility with activated oxygen source. Professor Pan’s talk focused on the textured MgO MTJs grown by PVD (physical vapour deposition). A brief review was given on the major milestones in the 50 years MTJs history, the scientific understanding of the coherent tunnelling mechanism, the experimental challenges in producing MTJs with giant TMR and the potential technological applications of MTJs. He then presented the research activities that Plymouth has been involved in including the DTI MNT project for the successful development of the Aviza StraIon fxp tool – the world’s first 300 mm ion beam deposition tool for MRAM and spintronics, and the work on MgO MTJs using their recently installed Nordiko 9550 PVD tool.


The morning’s session was concluded with the final talk given by Dr Robert Quarshie, Director of Materials KTN on a new funding initiative for pan-European materials projects (Matera+). The Matera+ call was launched on 16th March covering three major themes on multifunctional materials, engineering structural materials and bio-based and bio-inspired materials. A 1.5M euro has been allocated from the Technology Strategy Board to support UK participants together with a total call budget of 23.5 M euro provided by participating countries/funding bodies across Europe.

After lunch held in the reception area of the new NPL building at Teddington, two groups went to visit NPL laboratories involved with measurements related to the programme of the day.

The afternoon session of five talks was chaired by Professor Genhua Pan from the University of Plymouth. The first talk after lunch was given by Professor Mike Gibbs, Department of Engineering Materials, University of Sheffield, and was a lively presentation of the latest ground-breaking research being performed in Mike’s team. Mike started by stating how a detailed understanding of the physics of magnetic nanowires (thickness 5 – 20 nm, width 50 – 600 nm) have lead to a number of advanced applications and went on to explain three of these. The first involved an automotive whole turn steering sensor. This used magnetic logic to determine the number of complete turns of the steering wheel, something not previously possible with common fine angle sensors such as Hall probes. The next application involved using nanobeads to promote the growth of Schwann cells to repair nerve damage. The final example generated considerable interest from the audience and involved using a network of wires to confine atoms from an atomic lattice. In principle these could then be moved around and this could find use in quantum computing.

Dr Eugene Melikhov from the Wolfson Centre for Magnetics, Cardiff University, presented work on three areas of research. The first of these concerned magnetic refrigeration and Eugene showed that a temperature change of 17ºC had been achieved. Special phase behaviour has been observed with a ferromagnetic phase existing above the Curie temperature. Next, magnetostrictive materials were discussed. Eugene showed that by substituting atoms it was possible to alter the anisotropy. The final part of the talk concerned heat treatment and Eugene discussed how different cooling rates alter the structure from random for quenching to spinel for slow cooling. Eugene concluded that by chemical substitution and/or heat

treatment the properties of cobalt ferrite can be enhanced. The potential for using modified cobalt ferrite in multiferroic structures was highlighted.

Dr Markys Cain from the National Physical Laboratory talked about the resurgence in multiferroic materials that has occurred in recent years as a result of developments in the production of composite materials. Multiferroic materials that are strain mediated exhibit the unique ability of being able to change the magnetic behaviour through the application of an electric field and the electric behaviour through the application of a magnetic field. Markys suggested that this could lead to many exciting opportunities. Methods that have been developed at NPL to measure this magnetoelectric effect were described and included a method to measure the voltages developed when a magnetic field generated by an electromagnet was applied. The resulting voltage is produced without the need for power making this behaviour attractive for situations where energy efficiency is important.

A One-Cent-Room Temperature Magneto-electric Magnetic Field Sensor was described by Dr Neil Mathur, Department of Materials, University of Cambridge. Neil described how a commercial multilayered capacitor could be used as a magnetic field sensor. After the capacitor had been poled, the application of a magnetic field produced voltages at the electrodes. A voltage of 10 mV was generated in a magnetic field of 100 mT. The interdigitating electrodes of these

capacitors are now made from nickel and with a dielectric of BaTiO3 the required multiferroic structure exist. Neil explained that in practise it is hard to envisage applications for these sensors, but they do provide a nice study of electrically driven magnetic charges. Neil has set up a first year undergraduate practical using these cheap sensors that explores the phenomenon of ferromagnetism, ferroelectricity, magnetostriction, magnetoelectric coupling, piezo-electricity and pyroelectricity.

The final talk of the seminar was given by Dr Ann-Karin Axelsson and continued the multidisciplinary theme of the day with a talk that included chemistry. Anna covered the growth of epitaxial CoFe2O4 on various commonly used substrates. The majority of the work used SrTiO3 Despite the significant mismatch between these, crystallographic analysis confirmed an epitaxial relationship. Annealing was used to introduce structural recovery and magnetic measurements were performed at different annealing temperatures to evaluate this. From the results it was possible to establish the chemistry of this recovery. This provided information on the growth parameters needed to achieve optimised magnetic properties. Anna showed that be using post-oxygen annealing optimal dielectric properties of BaTiO3 and optimal magnetic properties of CoFe2 O4 are achieved.Dr Michael Hall, National Physical Laboratory, and Professor Genhua Pan, University of Plymouth, Faculty of Technology


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UKMAG seminar More Electric Aircraft, at University of Bristol, 2 April 2009

Left: Dr John Cullen, Rolls Royce plc (new UKMAG Vice-Chairman) and Dr Cris Emson, Infolytica Ltd

The seminar opened with Chris Ovenden of GE Aviation presenting

Introduction to the Electrical Power Systems National Technical Committee, or NTC, by setting it in its historical context. “More electric” aircraft

technologies have been very popular since the 1990s and many were incorporated into the A380 and B787 aircraft in the 2000s. The A320 and B737 should be replaced by “all electric” aircraft in the 2010s.Chris then summarised the benefits of the “all electric” aircraft as the removal of hydraulic and pneumatic systems, improved reliability and maintainability, and reduced fuel burn giving reduced costs and lower environmental impact.The purpose of the NTC is to gather information on electrical power systems with which to advise government, government/industry panels, and influence international research programmes through common membership. The NTC themes include new materials, electrical machines, power electronics, thermal management, distribution architectures and condition monitoring. Current NTC membership covers industry, academia and government bodies. Operation is through quarterly meetings defining technology roadmaps, ie who does what.NTC achievements include launching several projects (eg ELGEAR), involvement in related electrical projects (eg SEAS DTC and MOET), identification of technologies of value to the UK, and keeping the roadmap up-to-date. Current activities include Aviation Power Up, a £30M four-year

project examining the electrical system aspects of the next generation single-aisle aircraft.In Promoting Collaborative R&D through UK Aerospace Ruth Mallors introduced us to both the Technology Strategy

Board (TSB) and the Aerospace and Defence KTN or Knowledge Transfer Network. The TSB is a national body set up to invest £1B from 2008 to 2011 in technology i n s p i r e d i n n o v a t i o n in fields that include advanced m a t e r i a l s , high value manufacturing, e l e c t r o n i c s and electrical systems.The TSB aims to

understand market needs and support the most innovative and competitive responses in, among other sectors, energy generation/supply and transport.The TSB works with government to address societal challenges to give business the future market definition to be competitive in several areas including low carbon vehicles and intelligent transport systems.The Aerospace and Defence KTN, funded by the TSB, is a single network across

business, government and academia which fosters collaborative R&D in the sector. The TSB has defined objectives,

activities and metrics for the KTN that can be summarised as: drive and stimulate national aerospace technology strategy, broaden membership and collaboration, enable access to funding. However, progressing a common set of advisory and operational objectives for sectors (eg materials and electrical power systems) is undertaken by national technical committees.The KTN’s programme for 2009 includes the RAeS, regional annual conferences, and international networking. Communications include fortnightly newsletter, webinars, and quarterly briefings. Visit www.aeroktn.co.uk for further information.James Thomas of Goodrich presented on Electrically Actuated Landing Gear for a Civil Aircraft Application. The paper compared hydraulic and electrical actuation and particularly how electrically actuated landing gear can help achieve the objectives of the Vision 2020 document. The focus was on main landing gear (MLG) and nose wheel steering (NWS) for the well-established A320 aircraft so that comparisons with existing equipment can be made.The prime objective of the study was to totally remove hydraulic fluid from the wheel bays by replacing the hydraulic system with a +/-270V DC supply. There are a number of challenges in achieving this reliably and compactly eg mounting two electrical drives on one shaft such that one drive can provide full performance even when the other suffers an open- or short-circuit fault.

The solution chosen used double 3-phase fault tolerant p e r m a n e n t magnet motor topology where the 3-phase star connected w i n d i n g s are totally i n d e p e n d e n t (ie electrically, magnet ica l ly and thermally) of each other. When, for example, one phase becomes short-circuited,

either externally or internally, the other phases of that 3-phase winding are also shorted to rebalance that 3-phase


unit. The required rated torque is then produced by increasing the current in the unfaulted 3-phase winding.The paper given by Pat Wheeler of Nottingham University complemented James Thomas’s as it too dealt with landing gear within the ELGEAR (electrical landing gear extension and retraction) programme. However, Pat’s presentation considered a Dual Output Power Converter with Mutual Power Circuit Components for a future single aisle narrow-body civil aircraft.The large and heavy parts of a power electronics converter suited to the above are the DC link energy storage devices, control platform and heat-sinks for the power semiconduc to r devices. Where there is a dual load it is possible to minimise the impact of these parts by sharing them between the two converters that supply the dual loads, especially where, as in this application, only one of the loads is supplied at any instant.Pat’s talk described the simulation, build and test of a +/-270V DC converter with an FPGAS (ASIC) based control platform. The loads (brushless DC motors) were two separate electro-mechanical actuators EMAs, one for extension/retraction and the other for steering. The motor currents were filtered to achieve the specifications on the harmonics.A particularly interesting part of the study was the consideration of regeneration (40kW) to the aircraft electrical system which is not normally allowed.With his Motor Sub-System Requirements for UAV Actuation Applications Chris Whitley of Triumph Actuation & Motion Control Systems (UK) moved the discussion on to unmanned (combat) aerial vehicles (UAVs and UCAVs), specifically those of medium to large size (1 to 10 tonnes). In addition to their military applications UAVs can be used in the commercial realm for fire watch and coastguard duties as well as

Speakers from left: Dr John Cullen, James Thomas, Dr Ruth Mallors, Dr Jiabin Wang, Dr Neville McNeill, Dr Rebecca Todd, Prof Barrie Mecrow, Graham Dodd, Chris Whitley, Prof Pat Wheeler

some roles currently occupied by manned helicopters and aircraft.Actuators for UAVs tend to fall into two categories: efficient, highly dynamic ones (3 to 10Hz response) such as primary flight controls which can be back-driven by applied loads and alternatively less dynamic ones such as landing gear with low duty cycles and actuation times measured in tens of seconds but having no requirement for back-driving. The former tend to

have low-ratio and the latter high-ratio gearboxes. By examining a typical example of each type Chris showed that while the gearboxes were different, the motor requirements were similar. Further, the benefits of electric actuation in UAVs are maximised by using motors optimised for high torque/low speed performance.Chris examined the electrical loads on a twin-engine UAV having a take-off weight of over 5 tonnes. While the number of motors plus actuators approached 65, with peak power rating per device ranging from 20W to 500W giving a total installed power of about 3.7kW, the mean power drawn from the supply would be around 300W with occasional excursions to 1.8kW and so the existing 28V supply standard could probably be used. Chris concluded by noting that the accelerated development times of UAVs offer an excellent opportunity

for the introduction of electric actuation in a short timescale compared to conventional aircraft programmes.

The first presentation of the afternoon, Overview of MEA/National Projects, was given by Graham Dodds of Airbus UK. Graham provided an overview of the Airbus led MOET project. This large project co-funded by the European Union has 62 industrial and academic partners and is concerned with the development of technologies for more electric large

civil aircraft. It is anticipated the adoption of more electric systems on aircraft will lead to reduction in fuel burn, improved m a i n t e n a n c e and a reduction in unexpected delays in aircraft turnaround. The main objectives of the project are to develop and validate new electrical networks and the associated e n a b l i n g technologies for future aircraft e l e c t r i c a l systems with an installed power of around 1MW. The expected outcomes include

full electrical system benchmarking, validated component and system models and demonstrations of component weight reductions. To date an electrical system optimisation tool has been developed and a full scale large aircraft power systems test rig has been commissioned at the Airbus facility in Toulouse. A smaller scale network appropriate to regional, business jets and rotorcraft, has also been built at Alenia in Naples. During his presentation Graham introduced the range of actuation, power conversion, distribution and generator technologies that had been supplied by the partners. The final stage of the project, which ends in December this year, involves the validation of the simulation tool against the test rig results. The results of the project are to be disseminated at a MOET forum to be held in Barcelona, Spain, 7-11 September, in conjunction with the 2009 EPE Conference (13th European Conference on Power Electronics and Applications). At the end of his

UKMAG seminar More Electric Aircraft contd...


presentation Graham also summarised some of the activities being undertaken in the UK funded via the TSB including the 300kVA and AMES projects concerned with large aircraft generators and distribution systems.

Professor Barrie Mecrow’s presentation, Drive Train Solutions for Solar Powered UAVs, described research which had been undertaken at the University of Newcastle in association with Qinetiq on a lightweight and highly efficient drive train solution for a solar powered uninhabited autonomous vehicle (UAV). This aircraft has a wingspan of 18m and target weight of 30kg. The weight and power requirements of this platform are significantly lower than other UAVs such as NASA’s Helios for example, making the drive train design more challenging. A range of propulsion motor technologies were considered for the application with the final candidate selected on criteria which included a mass penalty for reduced efficiency. The final choice was a direct-drive, brushless DC permanent magnet, external-rotor, radial-field machine with a concentrated wound slotted stator lamination. A 34 pole, 27 teeth arrangement was considered the optimum arrangement. The use of a low loss lamination material was critical to realising the desired level of efficiency. A 6.5% silicon, 0.1mm steel manufactured by JFE Steel in Japan was identified as having very low loss as a result of its high silicon content and thin laminates. Despite the brittle and fragile nature of this material the stator core pack could be formed using wire-erosion cutting. Test results from the final prototype machine were presented and indicated a motor efficiency of 94% and a drive system efficiency exceeding 90% at altitude, these figures relating to the most energy critical operating mode of maintaining the UAV’s altitude during darkness. An outcome of the project has been the demonstration of 82 hours of non-stop flight for a UAV in July 2008, breaking the world record of 30 hours by a considerable margin. Following the presentation there was a lively discussion over the most appropriate lamination material for such applications.

The next two papers in the afternoon were concerned with control and operation of fault tolerant permanent magnet generators. These machines are designed such that each winding phase is to a degree magnetically and thermally isolated and can be controlled independently.

Dr Rebecca Todd’s paper Control of Multi-Phase Fault Tolerant PM Generator, introduced the UAV electrical power system rig installed at the University of Manchester, developed

in collaboration with Rolls-Royce and funded under their University Technology Centre scheme. This full scale is capable of emulating an embedded gas turbine generation system, comprising a 70kW LP shaft fault tolerant permanent magnet generator (PMG) and a 30kW HP shaft switched reluctance generator connected to a DC power distribution system. The various loads required by the UAV platform can be emulated using a series of configurable active and passive load banks controlled via a fieldbus. The operation of the 5 phase, 70kW PMG was then described in more detail with regard to normal and faulted behaviour. Each phase of the machine is controlled via an active power semiconductor H-bridge connected to a common DC output bus. A control scheme structure for this type of machine was outlined and the power sharing between phases and the regulation of the DC output of the generator was considered during a short circuited winding fault. Practical results showing operation of the controller on the 70kW PMG test rig indicated the attributes of a 0.1 second settling time following a fault and good power sharing between the remaining healthy phases.

The paper by Dr Jiabin Wang, An On-Line Winding Fault Detection Technique for Fault-Tolerant Permanent Magnet Machines, outlined research being undertaken at the University of Sheffield into fault detection techniques for such machines. The approach proposed in the paper is to introduce a single search coil wound in series around every second tooth of the stator lamination. It was demonstrated initially through finite element field analyses on a 5-phase fault tolerant machine that this arrangement would yield a detectable signal for both full and partial, inter-turn, phase winding short circuits. Furthermore the phase orientation of the fundamental component of the search coil signal could be used to indicate the particular phase in which the fault was located.

Methods of implementing the fault detection algorithm in a practical system were outlined where significant measurement noise would be present. The preferred method was based upon the use of a 4th order Kalman filter to extract the magnitude and phase of the fundamental and 5th harmonic components from the signal. The technique has been experimentally validated on a small laboratory machine and showed good immunity to noise introduced by the PWM switching of the power converter. The practical results indicated robust fault detection at medium to high speeds. The sensitivity of the detection techniques deteriorate at low speeds and with low number of

short-circuited turns. It is also affected by imperfect machine construction and phase imbalance.

Dr Neville McNeill presented research at the University of Bristol into lightweight magnetic components for operation at high-temperatures, Lightweight Wound Components for Application in MEA Systems. A design approach for compact switched-mode power supply transformer was described. The operating frequency of the transformer was set at 200 kHz, requiring the use of a low-loss core material, in this case a ferrite. Ferrites with Curie temperatures up to 300ºC are becoming increasingly commercially available. However their loss-minimum temperatures are still typically in the order of 90-100ºC with the possibility of thermal runaway in a magnetic component if the core temperature exceeds this. The ambient temperature for the example design was 120ºC, therefore necessitating operation of the ferrite core material at well above its loss-minimum temperature. However, stable operation without runaway may be attained if an adequate stability margin is ensured during the design. As an example, a toroidal design was evaluated. The transformer was encapsulated within an aluminium containment can for effective heat dissipation. The mass of the transformer, including the can, is approximately 28g and stable operation was attained at an output power exceeding 350W, representing a power density exceeding 12.5kW/kg. Another component considered in this presentation was a choke design for use in a high-temperature power converter. The operating frequency is much lower here at 10kHz and the ratio of ac to dc flux density excursion is also low so conventional laminated steel was used for most of the magnetic circuit. However, a permanent magnet (SmCo) is located in the choke’s air-gap in order to increase the steel’s effective saturation flux density, allowing a reduction in the component size. Again the component is encapsulated in an aluminium containment can for effective heat removal. It was shown that by designing the component with air gaps on each side of the permanent magnet, the extent of demagnetisation imposed when the load current is applied may be limited. An energy density of 0.49J/kg is attained compared to typically 0.28J/kg with a conventional component.Dr John Cullen, Rolls-Royce plc, and Prof Phil Mellor, University of Bristol, Dept of Elec & Elec Engineering


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UKMAG members news contd...

QinetiQ has won and started to deliver on a £3.5m contract to investigate

how the generation and distribution of electrical power on defence vehicles can be improved by using 610 Volt technologies against a background of ever increasing demands for electrical power. QinetiQ has established and leads a team including BAE Systems and ProVector Ltd to deliver this contract.

The programme runs through to the end of 2009 and will demonstrate improved electrical power capability in Armoured Fighting Vehicles (AFVs).

Awarded by the MOD Future Business Group, this Technology Demonstration Programme will see the existing 28 Volt system uprated in a demonstrator Warrior 2000 AFV to one that can generate and safely distribute electrical power at 610 Volts for high demand loads, yet still deliver 28 Volt supplies to existing equipment.

Today in addition to the standard vehicle electrical equipment, driveline, management systems and communications kit, most AFVs and Protected Patrol Vehicles will include advanced situational awareness, sensors, personnel and vehicle cooling systems, various other power-hungry systems plus a growing array of future technology – all of which place an increasing burden on the existing 28V generating systems. This high voltage architecture and system is also directly applicable to the wider military vehicle fleet and will be used to inform the development of power generation and distribution systems for future vehicles.

QinetiQ wins demonstrator programme to investigate use of 610V technology in military vehicles

The programme builds on QinetiQ’s extensive vehicle electrical power and propulsion research and development experience and its expertise in the design of high efficiency permanent magnet electrical machines. This expertise will be used to produce designs for a compact main engine generator and for a completely new auxiliary power unit. Each generator will have an output that

is double that of the original Warrior generator – effectively quadrupling the vehicle’s power generation capability, while providing much greater flexibility in power management and control.

“This team will deliver a best-in-class solution within a demanding timescale,” explained Chrys Stevenson QinetiQ Platform Systems Sales & Marketing Director. “A significant milestone has already been achieved as the programme passed its Critical Design Review. We are now bringing together the equipment necessary to commence integration on a rig prior to installation in to a Warrior based prototype vehicle later this year. The programme continues

to demonstrate the effective working relationships established between the three main companies that builds on their respective technical strengths to quickly demonstrate the potential for this technology.”

David Wragg, the BAE Systems’ IPT Leader for Emerging Programmes supported this and added: “This is an exciting programme that will demonstrate how technology insertion can sustain the growing electrical power requirements for both new and existing land platforms plus contribute to setting the design standards for future vehicles and requirements.”

Jim McMenemy, Project Manager within the MOD Future Business Group concluded: “I am very pleased with the progress already made by the team on this very important project. The output will inform vehicle IPT’s of the potential introduction of this technology which could dramatically improve the overall electrical power capability of our vehicles.”

Cobham rebrands three prominent technology design, development and testing businessesThree prominent technology design,

development and testing businesses, ERA Technology, Culham Lightning and Vector Fields, have been brought together under the new name of Cobham Technical Services - as part of a group wide rebranding programme by FTSE 100 parent company Cobham plc.

Cobham plc has revenue of £1.5 billion and employs more than 12,500 people worldwide on five continents, with customers in over 100 countries. In the past, individually branded business units have provided products and services to primarily aerospace and defence customers, many of whom have been unaware of the breadth of capabilities available to them from across Cobham. The unification of all businesses under a single unified brand is designed to make it easier for customers to understand the group and highlight the career opportunities available to current and future employees.

Cobham Technical Services brings together over 250 people in three businesses operating in related consultancy and technology design areas.

ERA Technology, based in Leatherhead UK, started life as the 'Electrical Research Association', a cooperative organisation undertaking research predominantly associated with electricity supply and use. Today, it offers leading-edge design, development and consultancy services but across a broader range of markets from electronics and communications systems, to antenna technology, safety and EMC, and reliability engineering. Culham Lightning of Abingdon UK, is dedicated to understanding the problems relating to the direct and indirect effects of lightning strikes. It provides consultancy and testing services to clients in aerospace and other sectors including wind power and oil and gas. The business has made significant contributions to lightning standards and best practices used in many applications, particularly aerospace.

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Abstract The design of low noise power transformers requests a fundamental understanding of the acoustic and mechanical behavior of its structure. Sources of noise are identified and investigated by measurements and numerical analysis. Additional to the noise sources the dynamic response of the structure and sound propagation plays a crucial role in transformer noise. Measures of sound reduction are discussed and their effectiveness are illustrated on a manufactured and delivered power transformer.IntroductionUrbanisation and growing cities leads to new requirements to the noise emission in populated areas. Increasing living standard and energy demand leads to higher sensibility of noise and more restrictive noise emission regulations. Customers demand low noise power transformers. Specific requirements for low noise transformers can be:• very low noise levels• individual noise thresholds for spectral octave bands• limitation of space and weight• acoustic enclosures are not permitted

Due to the fact that low noise transformers are installed in cities, weight and dimensions are limited. This complicates the development of low noise power transformers. To solve the problem the sources of noise and the vibro acoustic behaviour of transformers must be investigated carefully by measurements and

numerical simulations and measures for noise reduction must be identified. An overview of investigations, noise reduction measures and their effectiveness are shown on a 420MVA power transformer.

Sources of noise and vibroacoustic behaviourIn order to improve the design of power transformers with respect to noise, it is important to understand the mechanical and acoustic behaviour in detail. The prime task is to find measures to reduce sound generation. In transformers the following sources of noise are identified:• sources of load current noise• sources of no load noise• source of cooling equipment noise.

Additional to the optimisation of sound sources the transmission of sound from the sources to the environment has to be considered. Here the tank as a sound emitting surface plays an important role.

A Sources of load current noiseSources of load current noise are vibrations due to electromagnetic forces in windings, magnetic forces on iron components and magnetostriction in steel parts. The critical quantity is

the magnetic stray flux. A numerical model was developed to study the vibrations of windings of a 70MVA transformer. After the calculation of the static displacement due to pressing, the working point for the elastic material properties (differential E-modulus) was defined. The excitation force is known from a previous calculation step, which computes the lorentz forces on windings from the magnetic flux and the current in the conductor. Windings are a complex structure with copper and insulation parts (conductor paper, axial distance spacers etc) as shown in figure 1. The influence of radial distance sticks between windings (LV, HV) was investigated (right in figure 1). Comparision of the simulation of resonant modes with and without radial

distance sticks with the measured transfer function revealed, that the windings are not coupled mechanically by these sticks. Analysis of the resonant modes showed as well, that many of the resonant modes

Low Noise Power Transformers - more energy in large cities with less noiseDr Peter Hamberger, Siemens Transformers Austria GmbH & Co KG Werk Linz, Krauss-Strasse 7, 4020 Linz, Austria, tel: +43 51707-71004, fax: +43 51707 55440, email: [email protected][This paper was presented at the UKMAG one day seminar Noise in Electrical Machines, held at Cardiff University on 4 February 2009 - UKMAG members can access the full presentation on the Society’s website www.ukmagsoc.org]

Figure 1 FEM model of a high voltage winding of a 70MVA transformer

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were not axisymmetric as shown in figure 2. The complex geometry of windings and the 3D modes require a 3D model for full description. This finding was confirmed by laser doppler vibrometer measurements [1,2,3]. Three limbs of the 70MVA transformer were modelled to compute the axial and radial winding vibrations. The model was calculated without and with oil coupling.

In the calculation without oil coupling, the windings of the middle limb shown smaller axial vibrations. This is due to the mechanical coupling with the clamping

plate. Oil coupling (figure 3 right) has a big influence on vibrations. The limbs are not only connected mechanically but also strongly coupled through the oil and influence each other. Moreover

the oil coupling and the electrical phase difference between the three limbs result in a directed noise radiation. These results show that the complete winding system has to be considered. The windings influence each other through oil coupling and have an impact on pressure propagation to the tank.

B Source of No Load NoiseT r a n s f o r m e r cores are the main source of transformer no load noise. T r a n s f o r m e r cores are built of high-inductive, grain orientated electrical steel sheets (GOES) with typical thickness of 0.3mm. The origin of core noise are (a) magnetostrictive vibrations of the core laminates and (b) interlaminar magnetive forces. The contribution of each factor to the overall core noise is still an open topic of discussions and investigations.Handling magnetostriction in empirical and numerical models is very complex, since the magnetic and magnetostrictive properties are highly nonlinear and show distinctive hysteresis loops. A further complexity of GOES material is given by the anisotropy of magnetostriction and magnetic curve. With rising angles

with respect from the main direction of grain orientation, the magnetic and magnetostriction properties get worse. The anisotropy is the reason why the core joints region are the main source of transformer core noise (figure 4). Next to the joint gaps, magnetic flux components in cross direction arises, leading to increased magnetostrictive vibrations and losses.Due to its structure of stacked thin laminates, in additional the mechanical dynamic beavior of transformer cores is quite complex. To explore the dynamic behaviour of cores, additional measurements were

done on a test core, which had two steps (geometric data shown in table 1)

Window height 900mmCenter Limb Distance 500mmBmax 170mmBmin 110mm

Again laser doppler vibrometer measurements were done on the small side of a test core, excited with 50Hz. As shown in figure 5, the two steps of the test core have different vibration characteristics for the different modes. At lower frequency modes the inner steps show higher velocity than the outer step. At higher frequency modes the picture reverses (figure 5).

The transfer function of the core was measured as response at different points (figure 6) of a delta impulse. The response of the core did show broad and strongly damped resonances. The only one exception is the 388Hz resonance peak, which stems from the tie bars of the clamped test core.

The broad resonances suggest, that the different laminates of a core do not vibrate independently but exchange energy by local contacts. These interactions by local mechanical contacts lead to a nonlinear behavior of stacked cores. A tendency of frequency spectra linked with geometrical data (shift to lower or higher frequencies) is not fully explored yet.

A measure to improve no load noise is to reduce the excitation of vibration by the selection of high quality grain orientated silicon steel. Because of the complex behavior of transformer cores a link from material parameters only to transformer noise seems to be difficult.

Correlations between material magnetostriction properties and transformer noise were introduced by [4][5]. These references use FFT analyzed magnetostriction waveforms to calculate a sound level based on velocity [4], denoted as LvA or based on acceleration [5], denoted as LaA. The possible correlation between the magnetostriction properties of grain orientated silicon steel materials and noise were studied.

Figure 2 Displacement of the windings in the resonant mode at 96Hz of a 70MVA transformer

Figure 3 Displacement calculated without (left) and with (right) oil coupling. (Top: axial part of the vibrations, middle: radial part

of the vibrations, bottom: magnitude of the tank surface)

Table 1 Dimension of test core

Figure 4 Measurement of magnetostriction velocity at different positions of a 400kVA transformer. By means of laser doppler vibrometer. Velocities

are highest at T-joint of the three limb core.


Results of six 630kVA transformers of this study will be presented here. The transformer cores were manufactured with 0.30mm high permeability material.

Three transformers were manufactured with material of strip 1 and the other three with material of strip 2. From all strips samples were taken to measure magnetostriction at 50Hz between 0.8T and 1.95T. The dimensions of the samples were 600mm in rolling direction and 100mm in transverse direction. The samples were hanging freely and stress free, and were clamped at the upper end. The elongations were measured at the lower end by mean of a laser doppler vibrometer. Each measured waveform was analysed with FFT, and this FFT spectrum was used to calculate the A-weighted noise pressure in function of polarisation. The comparision of the calculated LaA and LvA values are compared with measured sound pressure levels of the transformer (figure 7).

In the lower range of the polarisation (J<1.6T) the calculated LvA values of the strip2 material seem to have lower noise. Above 1.7T the strip 1 material shows in the LvA model an improvement of 1-1.5dB compared to the strip 2 material. In contrast the measured sound pressure levels of transformers manufactured with strip1 material show lower sound pressure levels of 2-4dB, independent of the polarisation value. Concerning in absolute values, it can be seen that the LvA model shows higher values than the measured transformer noise.

Using the LaA model similar tendencies between calculated and measured noise are reached. The of model LaA predicted difference in noise of strip 1 and strip

2 material is much smaller than confirmed by measurement. In absolute values the LaA model predicts lower noise levels.

Sound Transmission to ambientBeside the external cooling equipment on transformer the tank is the main sound emitting surface. Measurement and numerical analysis reveal that tanks have a dense set of resonant

modes. This fact will be illustrated later by a test tank discussed in this section. Measurements on manufactured t r a n s f o r m e r s showed, that the dynamic response of a

tank and the acoustic behaviour is very sensitive on environment conditions. Laser Doppler Vibrometer measurements on a 120MVA transformer showed for instance, that the vibration amplitudes increased by a factor two and the vibration shape of the tank surface changed during the heating of the transformer from ambient to steady state temperature. In order to analyse this behavior, a test tank (figure 8) was analysed.As noise source in this test tank a tree limb core was used. The vibration patterns of the tank generated by the core in the tank were measured two different times but at the same ambient conditions. Between the two m e a s u r e m e n t s the test rig was heated to 70°C top oil teperature and was cooled down to ambient. The vibration pattern of these two

measurements are quite different, which suggests a structural change (figure 9). In order to analyse this interesting fact modal analyses of the surface vibration patterns were performed. Both vibration patterns of the two measurements are a superposition of the same resonant modes. In this case two resonant modes, a 2/3 mode and a 1/5 mode are involved (figure 10). The resonant frequencies of the two modes are 98,5Hz and 101,2Hz. The structural change influenced only the phase and amplitude relation of the two modes, because of a slight shift of the resonance frequencies.

Dependent on the weight of the individual mode on the vibration pattern the sound emission is different. As shown, small structural changes, which are out of control, influence the sound emission. Examples of influence parameters beside temperature are strains due to welding or screwing. This fact makes it difficult to permit directly the sound emission with numerical methods. Whereas modal analysis of the tank with numerical methods seem to be feasible.

Measures The development of computation models for stray flux calculation, calculation of lorentz forces on windings and vibration of windings are essential for the development of low noise winding designs. Windings have to be designed for minimisation of exciting forces and avoiding winding resonances. The measurement of material parameters as the differential E-modulus of paper and

Low Noise Power Transformers - more energy in large cities with less noise contd...

Figure 6 Response of the core to a delta impulse. The core shows broad resonances

Figure 5 Measurement of vibration velocity map via laser doppler vibrometer scan. In the excited modes of higher freqency, the velocity

of the outer steps is higher than the velocity of the inner step

Figure 7 Comparison of calculated LvA noise levels (upper figure) and calculated LaA noise levels (lower figure) with measured

sound pressure level


pressboard under different clamping pressure conditions are important to describe the elasticity of the structure. For the core it is much more difficult to develop computation models for vibration. Here the source of noise has to be reduced in first order by selecting high quality grain orientated silicon steel. Correlations between core steel material properties and transformer no load noise are still not fully investigated. Computational models of tanks ensure to optimise the tank structure avoiding resonant modes near the excitation frequency as much as possible.

On the example of a manufactured and built 420MVA, 60Hz transformer

[6,7] the effectiveness of measures are illustrated as shown in Table 3.

Measure Noise reduction

designing windings with minimised exciting forces avoiding winding resonance 13dBconsidering core resonance

application of additional sound panels at positions with high 7dB tank vibrations

Conclusions Deep understanding of physical effects leads to effective measures for noise reduction of transformers. The development of powerful computation

models and measurement of material properties support the optimisation of the design in reducing excitation forces, avoiding resonant modes of windings, cores and tanks near the excitation frequency. References[1] Hamberger Peter, 3D-FEM Simulation for Investigation of Load Noise of Power Transformers Verified by Measurements, ICEM 2008[2] Hauck A, Numerical Simulation of Load-Controlled Vibrations of Power Transformers, Master Thesis, Erlangen, Germany, 2005[3] Hauck A, Kaltenbacher M, Simulation Eines 70 MVA Leistungstransformers, Teil 1 und 2

[4] M Mizokami et al Magnetostriction of Grain-Oriented Electrical Steel and Noise of Transformers, 24th Conference on Properties and Applications of Magnetic Materials, Proceedings 2005[5] I Masayoshi et al, Analysis of Noise Emitted from Three-Phase Stacked Transformer Model Core, Kawasaki Technical Report, No 39, pp29-35[6] Transformers Trade Press Day, 11 Dec 2008, Nuremberg transformer plant, Alfons Schrammel[7] Low Noise Transformers and Phase Shifters, TechCon Asia Pacific 2008, M Scala, H Prepartner, R Labinsky, G Leber

Dr Peter Hamberger, Siemens Transformers Austria GmbH & Co KG, Austria, [email protected]

Figure 8 The tank was excited by a delta impulse and the dynamic response was measured. The tank shows a high density of low

damped resonances

Figure 9 Vibration pattern of the same side of the test tank measured at different time points. Between the two measurements the test rig operated and heated up to oil temperature of 70°C. Before the second measurement the test rig was cooled down again. The

ambient conditions of the two measurements were the same

Figure 10 The vibration patterns of the tank surfaces measured at different time steps appear to be very different, but they can be considered as superposition of the same resonant modes, having the resonance frequency near the excitation frequency. Between the two measurements

only the phase and amplitude relation of the involved modes changed

Table 3 Effectivity of noise reduction measures on a build 420MVA transformer [6,7]

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The Materials Programme in the School of Metallurgy and Materials

at the University of Birmingham is a well-established facility dedicated to producing high quality, well characterised metallic materials, often in the form of single crystals, for use in many branches of research. Since its establishment in the 1970s, the Programme has enjoyed extensive UK Government Research Council support while gaining an international reputation for both its materials research and the high quality samples that have been prepared. The majority of the materials that we have produced have been used for the study of magnetic phenomena. Our services are available free of charge to any group receiving EPSRC funding.

The original motivation behind setting up the Programme was to ensure that the UK research effort in metal physics would not be rendered internationally uncompetitive for lack of high quality samples by providing a central, specialist materials preparation laboratory. This Programme has since expanded considerably and now acts as a national facility for preparing metal based samples for many branches of scientific research that range from the study of fundamental magnetic properties of exotic compounds to applied magnetostriction. Since its inception, the Programme has supplied over two thousand high quality samples to EPSRC-sponsored groups in around two dozen UK universities as well as the Daresbury and Rutherford Appleton Laboratories, Diamond, ILL and ESRF.

Close ties with these groups have given us experience of fabricating and characterising actual specimens for a range of experiments including elastic and inelastic neutron scattering, superconductivity, surface studies, heat capacity, NMR, magnetostriction, magnetic susceptibility, muon spin rotation/relaxation and magnetic X-ray scattering. These collaborations have also led to our hosting several visiting scholars over the lifetime of the Programme for periods ranging from a few days to several months.

This provision of samples has only been made possible by undertaking our own comprehensive research into crystal growth and metal purification, together with the development of equipment. It is this research that has underpinned the whole Programme and given us the adaptability to work in new areas in a way that commercial suppliers find impossible.

While the initial aim of the Programme was to purify and grow crystals of rare earth metals (our operation is still known by many as the Rare Earth Programme), it has since expanded to the point where we have worked on materials containing around 50 of the elements. While alloys or compounds of the rare earths and refractory transition metals still form the bulk of our effort, our present endeavour is to work with any metal-based material or metal

oxide where samples are required that are beyond the scope of the typical ‘physics’ or ‘materials science’ laboratory or commercial suppliers. Noteworthy features of our research have included refining several rare earth elements to the highest purities ever recorded and the growth of the first or largest crystals of several intermetallic compounds. Over the last few years we believe that we have also made significant advances in developing the image furnace technique for growing crystals of metallic oxides. An illustrative list of materials prepared can be found in our group website, details of which are given below.

The fundamental rule of all metallic sample preparation is that the methods used have to be closely tailored to the individual properties of the material concerned. Thus, work with any new material invariably involves background research and preparation techniques may need to be developed or modified to cater for its specific properties. The ‘materials properties’ of most relevance to sample preparation and crystal growth are the melting point, reactivity and vapour pressure of the component(s), the phase diagram

and crystal structure(s), while the availability of good quality start metals is also important. Of these properties, vapour pressure is undoubtedly the most important, for it determines how long a material can be heated. A high melting point may be inconvenient, but possibly all that is needed is more power, while a complex crystal structure does not necessarily mean that it is difficult to grow crystals. Likewise a reactive or radioactive metal may demand the use of ‘cleaner’ or more secure equipment, but a rapidly evaporating material (or, even worse, an alloy or compound with a rapidly evaporating component) can present a major challenge.

The range of specialised equipment currently in our laboratories is extremely comprehensive and comprises a range of melting facilities, several crystal growth systems (employing the Czochralski (Figure 1), RF float-zoning, optical floating zone (Figure 2), Bridgman (Figure 3) and flux techniques), metal purification and degassing systems and characterisation equipment. Much of it is unique, having been designed and built in-house since no commercially available systems exist that approach the vacuum capabilities (ie in the 10-9 to 10-10 mbar range) necessary to work with high purity reactive metals. As such, these home built systems represent exceptional value for money when

one considers that most commercially obtainable crystal growth systems typically cost four to five times as much as our home-built units, yet invariably have vacuum capabilities two or three orders of magnitude worse. Ancillary

Preparation, Purification and Crystal Growth of Metallic Elements, Alloys, Compounds and Oxides School of Metallurgy and Materials, The University of Birmingham

Figure 1 Tri-arc Czochralski crystal growth

Figure 2 Optical floating zone furnace


equipment includes arc furnaces and RF cold boat melting systems for alloy preparation, inert gas purifiers, vacuum stores for reactive metals, annealing and sintering furnaces, an X-ray Laue set for aligning crystals and cutting machines. Within the building, we also have access to the Department’s state of the art scanning and transmission electron microscopes and X-ray facilities.

As well as assembling the hardware for this Programme, we have not ignored what may be termed the ‘intellectual infrastructure’ necessary for a national facility. Thus, we have built up a

comprehensive computerised database of materials preparation information cataloguing details of crystal growth, purification, crucible compatibilities, crystal structures and phase diagram details for metals and compounds. This database currently has several thousand entries, cross-referenced so that if information on a particular material is not available, data on materials with a similar structure or generic type is displayed. Also, we have written programs to calculate vapour pressures and predict volatilisation rates for metals at elevated temperatures (this covers all metallic elements under both vacuum and inert gas environments) as well as simulations of Laue X-ray film patterns for all structure types. All of this information is made freely available to our collaborators to aid them in planning their research.

We help our collaborators in a variety of ways ranging from simply giving advice to groups who have preparation equipment of their own, but possibly are not sure of the best way to use it, to growing a single crystal and cutting oriented samples from it. Naturally, the former can be carried out rather more quickly than the latter! Our services are provided free of labour charges to groups who have EPSRC funding for their research, although we do request that start metals are bought for us and, where appropriate, crucibles are paid for if they are particularly expensive.

Although we have unrivalled materials preparation and crystal growth facilities,

we consider by far our most valuable asset to be the staff associated with the Programme, for in this type of work, experience is paramount. We are lucky, therefore, that the collective experience of our staff comfortably exceeds a hundred years! The current group leader, Professor Stuart Abell, was first associated with this Programme in the 1970’s and is an expert on crystal growth of functional materials. From 2010 he will be taking a back seat and the group leadership will be taken over by Dr Andy Williams, also from the Metallurgy and Materials Department, whose research interests include the processing and characterisation of magnetic materials and the development of magnetic characterisation equipment.

Day-to-day running of the facility is in the hands of Dr Seyed Koohpayeh and Dr Dave Fort. Seyed was a project student on the Programme from 2003 to 2007 when he carried out some first class work using our image furnace which has allowed us to add the growth and characterisation of metal oxide crystals to an operation that previously concentrated almost exclusively upon metallic elements, alloys and i n t e rme ta l l i c c o m p o u n d s . Dave, who first worked on the P r o g r a m m e in 1975 is recognised as having unique expertise on the purification of reactive metals, while many of our advanced crystal growth systems were designed by him. Although now semi-retired, he still spends a day or two each week working on the P r o g r a m m e . Since many of the samples that we prepare are used in c o n d e n s e d matter physics research, Dr E l i z a b e t h Blackburn and ProfessorTed Forgan of the C o n d e n s e d Matter Physics Research Group in the School of

Figure 3 Bridgman crystal growth

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Physics and Astronomy at Birmingham give the physicists perspective to what is essentially a metallurgical operation. Two long-serving technicians, Andy Bradshaw and Jeff Sutton, provide further assistance.Contact details:Group website http://www.eng.bham.ac.uk/metallurgy/crystal_home.shtmlProf Stuart Abell [email protected], tel: +44 (0)121 414 5168Dr Andy Williams [email protected], (0)121 4143959Dr Seyed Koohpayeh [email protected], (0)121 414 5249Dr Dave Fort [email protected], (0)121 414 5229Dr Elizabeth Blackburn [email protected], (0)121 414 4694Prof Ted Forgan [email protected], (0)121 414 4678

Dr Andy Williams, University of Birmingham, School of Metallurgy and Materials, [email protected]


Room Temperature Proximity Effect Across the Fe/GaMnAs InterfaceDr Francesco Maccherozzi, X-PEEM Microfocused Beamline, Synchrotron Soleil, France[This paper was presented at the UKMAG one day seminar Advanced Functional Materials, held at the National Physical Laboratory on 19 March 2009 - UKMAG members can access the full presentation on the Society’s website www.ukmagsoc.org]

By means of doping a semiconductor (SC) with ferromagnetic (FM)

impurities, it is possible to obtain a ferromagnetic semiconductor (FS). This strategy potentially allows the integration of spintronic devices in conventional electronics. Devices were realised with all-metallic structures, as giant magnetoresistance (GMR) [1] or tunnelling magnetoresistance (TMR) [2]: they can operate at room temperature but it is difficult to integrate them in existing semiconductor-based circuits. Since its discovery in 1996 [3] the (Ga,Mn)As has been the subject of intense research for its full compatibility with GaAs technology: this characteristic allowed the realisation of devices performing the basic tasks required in a spintronic device, as current driven magnetic writing [4] and spin injection [5]. Unfortunately the growth of (Ga,Mn)As presents challenging difficulties, for the low solubility of Mn in GaAs and its tendency to form MnAs clusters in the InAs form, and the highest Curie

temperature so-far obtained is still below 200K, preventing its use for practical devices.

On the other side, the FM/SC interfaces have a strong interest in spintronic, for the spin injection in semiconductors. It was shown that the formation of a Schottky barrier at the interface, could overcome the depolarising effect due to the strong conductivity mismatch between the FM and the SC, by forming a tunnel barrier at the interface. In particular through the Fe/GaAs(001) interface it is possible to perform efficient spin-injection at room temperature, thanks to the optimal magnetic properties of the thin Fe film [6], and to the lack of any magnetically dead layer at the interface [7]. The Fe/GaAs was shown to induce, even in static condition (no applied bias), an effective spin polarisation on the free electrons and nuclear spins in the GaAs layer [8], called ferromagnetic proximity polarisation (FPP). The effect is not due by stray fields, because its

sign depends on the choice of the FM material: with Fe it is antiparallel, and with MnAs is parallel. The density of states (DOS) at the Fermi level seems to play a role and it was proposed that the polarisation originates from a spin-dependent reflection of free electrons at the Fe interface [9].

The deposition of thin film of Fe on (Ga,Mn)As could then provide a route to control the magnetisation of the FS, by means of the FPP.

In order to selectively probe the Mn and Fe magnetisation we made experiments with X-ray Absorption Spectroscopy (XAS) and Magnetic Circular Dichroism (XMCD) at the resonant L-edges of Mn and Fe, on the APE beamline of Elettra Synchrotron. The shape of XAS spectra depends on the electronic configuration of the element and on the crystal environment. With the use of circularly polarised light (XMCD) it is possible to probe the magnetisation of a single element.


The (Ga,Mn)As substrates were prepared by the group of W Weghscheider of the University of Regensburg [10] by low temperature MBE. The deposition of thin Fe films (0-3 nm) was made ex-situ, therefore special care was taken to decap

and clean the (Ga,Mn)As crystals: the temperature required to desorb the As-protecting layer (400°C) would cause the formation of MnAs clusters, therefore different approaches were followed. The first set of samples was sputtered with Ar+-ions at 600 eV, resulting in a disordered surface and polycrystal Fe films. The FM properties of the (Ga,Mn)As were deeply affected by sputtering damage [11]. The second set of samples was prepared by a combination of low temperature annealing (180°C) and soft Ar+-ion sputtering at 45° incidence [12], in order to obtain an ordered and pure (Ga,Mn)As surface, and to allow the deposition of epitaxial Fe film in the bcc form. The magnetic characterisation showed that the magnetic properties of both GaMnAs, in terms of Tc and magnetic anisotropy axis, were not affected by the surface preparation. The Fe magnetic anisotropy axis were not

different from Fe/GaAs(001) thin films.

The XMCD spectra of Mn and Fe, taken at room temperature, had opposite sign, proving that the Mn spins align antiparallel to the Fe magnetisation [fig 1]. The magnetic hystereses measured

with the XMCD L3 signal of Fe and Mn have the same shape, but opposite sign, showing that the Mn magnetisation is always proportional to the Fe one. The ratio between the Mn and Fe XMCD decreases linearly with temperature, meaning that the strength of the proximity effect is stronger at low temperature. The proximity effect was still present above room temperature, at 330 K.

With the second set of samples, where the magnetic properties of the (Ga,Mn)As substrate were not affected by sputtering damage, we made a similar XAS/XMCD experiment below the Tc of (Ga,Mn)As in order to verify if the appearance of the FM in the (Ga,Mn)As crystal were in competition with the antiparallel layer. The measurements were made at ID08 beamline at ESRF synchrotron. Below Tc both the antiparallel and FM XMCD signals of the Mn were present, proving

that the FM ordering of the all (Ga,Mn)As film does not destroy the antiparallel proximity effect. The site-selectivity of XMCD allowed us to distinguish the XCMD signal coming from the MnAP and from the MnFM, because they have a different shape and they are shifted in energy. This also means that the two signals do not come from the same crystal site and thus that the proximity effect do not act on MnGa substitutional sites, that are responsible of FM in (Ga,Mn)As.

Figure 2 XMCD spectrum of Fe/(Ga,Mn)As with the coexistence of both the contribution from MnFM and MnAP, fitted with two experimental

template line shapes. (ID-08 beamline, ESRF synchrotron)

In figure 2 it is shown the deconvolution of an XMCD spectrum at the Mn edges, at T<Tc, in its FM and AP components.

The epitaxial quality and interface sharpness of the second set of samples made us more confident that the AP magnetic coupling was not due to Mn-Fe intermixing (and then to direct exchange) but to proximity effect of the Fe layer, on Mn ions embedded in the GaAs crystal. We estimated, on the basis of electron yield-photon yield probing depth arguments, that the MnAP region should extends for several GaAs unit cells, much more that the interface roughness (that is about 0.6nm). To definitely exclude the presence of Mn-Fe intermixing we performed a series of XAS-XMCD measurements on Fe-Mn films intentionally intermixed, deposited on the GaAs surface [13]. In figure 3 it is shown that in all the explored samples the XMCD line shape of the Mn is qualitatively different than the one measured on Fe/(Ga,Mn)As the XMCD L3 peak is also shifted in energy. This experiment give a strong support to our thesis of absence of Fe-Mn intermixing.

Recent bulk magnetometric measurements (with SQUID) on a series of Fe/GaMnAs samples with different Fe thicknesses (0 to 3 nm), showed that the presence of Fe increases the Tc of the (Ga,Mn)As underneath, linearly with the Fe thickness, up to 16%. This is a strong evidence of the presence of a magentic interaction between the Fe layer, and the all (Ga,Mn)As. We can suggest that the Mn AP ions could be coupled antiferromagnetically (AF) with the FM-MnGa and thus provide a path for the coupling of Fe with (Ga,Mn)As bulk. This would be consistent with the hypothesis that the MnAP are in interstitial sites, forming dimer with the MnGa because it is well know that the MnI-MnGa are AF coupled [14].

Figure 1 XAS/XMCD spectra of Fe/(Ga,Mn)As at room temperature at the Fe (a) and Mn (b) L-edges. The sign of XMCD peak is opposite, meaning that the Mn magnetisation is antiparallel to the

Fe and to the applied magnetic field

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Room Temperature Proximity Effect Across the Fe/GaMnAs Interface contd...

We think that the comprehension of the mechanisms originating the proximity effect could suggest new avenues for the design of room temperature spintronic devices.

Figure 3 XAS/XMCD spectrum of FeMn alloy films on GaAs(001),compared with the MnAP. The XAS of the alloy is broader

and less structures, and the XMCD is shifted at higher energy and more structured

XAS

(arb

.uni

ts)

655650645640635photon energy (eV)

XMC

D (arb. units)

A

B

(pure GaMnAs)

GaAs/Mn(0.2Å)

GaAs/Mn(0.2Å)/Fe

Antiparallel Mn

We found that the Fe is able to induce a magnetic order, above room temperature, in part of the Mn embedded in the GaAs across the Fe/(Ga,Mn)As interface. The Mn coupled with the Fe is not in MnGa sites. We suggest that the Fermi electron spin polarised at the Fe interface, could play a role in the FPP. The presence of the Fe was shown to increase the Tc of the (Ga,Mn)As.

Bibliography[1] M N Baibich et al, Physical Review Letters 61, 2472 (1988)[2] J M Daughton, Journal of Applied Physics 81, 3758 (1997)[3] H Ohno, A Shen, F Matsukura, A Oiwa, A Endo, S Katsumoto, Y Iye, Applied Physics Letters 69, 363 (1996)[4] D Chiba, Y Sato, T Kita, F Matsukura, H Ohno, Physical Review Letters 93, 216602 (2004)[5] Y Ohno, D K Young, B Beschoten, F Matsukura, H Ohno, D D Awschalom, Nature 402, 790 (1999)[6] F Bensch, G Garreau, R Moosbuhler, G Bayeruther, E Beaurepaire, Journal of Applied Physics 89, 7133 (2001)[7] L Giovannelli et al, Physical Review B 72, 45221 (2005)[8] R J Epstein et al, Physical Review B 65, 121202 (2002)[9] C Ciuti, J P McGuire, L J Sham, Physical Review Letters 89, 156601 (2002)[10] F Maccherozzi et al, Physical Review B 74, 104421 (2006) [11] F Maccherozzi et al, Surface Science 601, 4283 (2007)[12] M Sperl, unpublished[13] F Maccherozzi, M Sperl, G Panaccione, J Mina´r, S Polesya, H Ebert, U Wurstbauer, M Hochstrasser, G Rossi, G Woltersdorf, W Wegscheider, C H Back, Physical Review Letters 101, 267201 (2008)[14] K W Edmonds, N R S Farley, T K Johal, G van der Laan, R P Campion, B L Gallagher, C T Foxon, Physical Review B 71, 64418 (2005)Dr Francesco Maccherozzi, X-PEEM Microfucused Beamline, Synchrotron Soleil, France, [email protected]

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STUDENT BURSARY SCHEME As part of its role in securing the future vitality of the magnetics community, the UK Magnetics Society has introduced a competitive bursary scheme to assist postgraduate students to attend international conferences. £250 bursaries are available to support attendance at conferences of international standing in the UK or abroad, in subject areas which reflect the interests of the UKMagnetics Society membership. The award of a bursary is intended to acknowledge the student’s contribution to the magnetics community and act as a catalyst for attracting additional support.

The following eligibility criteria will be applied in selecting students:

• restricted to full-time postgraduate students, ie notcontract research staff;

•restrictedtostudentsfrominstitutionswhicharemembersof the UK Magnetics Society;

• students should be presenting a paper, either poster ororal;

• applications from students presenting a paper oncollaborative work between two or more members of the UK Magnetics Society (academic or industrial partners) will be particularly welcome;

• successful recipients of student bursaries are requestedto provide a brief review of the conference to appear in a subsequent issue of Magnews.

DENNIS HADFIELD MEMORIAL AWARD In addition to the Student Bursaries, the annual Dennis HadfieldMemorialAwardwillbemadeforthebestStudentBursary conference report published in Magnews each year. The award will be announced at the annual Ewing Event, held each December, and the award winner will be invited to attend the Ewing Event free of charge and will receiveaframedcertificate.

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Scope and FormatMagnetics is an exciting area which is of growing importance to vital elements of many sectors of industry. Cardiff University is starting a new, one year, MSc course in Magnetics which will cover the science and engineering of modern magnetism and advanced magnetic materials for graduate students. This course will provide a qualification in Magnetics that is unique within the United Kingdom, and probably within the world. The course should appeal to graduates with first degrees in Electrical/Electronic Engineering, Materials Science, Physics or related subjects, or as for graduates with degrees in other fields who wish to study engineering. The course comprises magnetics core modules, electronics core modules, optional engineering modules, and laboratory work, including focused research study and a research project with industrial relevance.

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The marvellous development of the rare earth magnet industryProfessor Luo Yang, IEEE Member of PM Technical Committee (TC-15), Beijing, China, October, 2008, [email protected][This is a continuation of the article which appeared in the Winter 2008 issue of Magnews]

Figure 6 Price in Japan, China and ratio between them

1996 1998 2000 2002 2004 2006 20080

40

80

120

160

200

0

0.2

0.4

0.6

0.8

1

Ratio (C

hina/Japan)

China price Japan price Ratio

Pric

e ($

/kg)

China Japan SEA USA Europe Other-3.7% -2% -2.1% -3.4% -5% -6.9%

Table 1 Average annual reduction rate of bonded NdFeB magnets in different regions during 1996-2001

Price of bonded NdFeB magnetsUnder normal conditions, without inflation, magnet prices should gradually fall with market expansion. The average annual price reduction rate in different countries during 1996-2001 is listed in Table 1.

Table 1 shows that the average annual price reduction rate ranges from -2% to -6%. The hardware used in China was less advanced so the magnet production in China was not as good as in developed countries. Consequently its sales relied on lower prices from the very beginning. Thus the magnet price gap between China and the others became larger and larger, even though MQ powder is used by all of them. Prices in Europe, USA. and Japan are different, but comparable. Prices in China, Japan and the ratio between them during 1996-2008 are plotted in Figure 6.

It can be seen from Figure 6 that the bonded NdFeB magnet price in China

is always half of the price in Japan. In 2002 the price in Japan dropped sharply by 17%. It sharply increased in 2007 by 27%, but price ratio between China and Japan remained the roughly the same.

The price of bonded NdFeB is referred mainly from [8]. In order to be sure

about the prices in China several magnet manufacturers were visited by the end of 2007. The price change of bonded NdFeB in different countries since 2000 is shown in Figure 7.

It can be seen from Figure 7 that:1 The prices of bonded NdFeB magnets in different regions have deceased year by year. However, the rate of decrease is quite different between countries and years. During

1996-2001 annual prices decreased at a rate of 3.7% in China; it was 2% in Japan, 2.1% for SEA, 3.4% in USA, 5% in Europe, and 6.9% for the others. The magnet price in Japan was one of the highest and its change is greatest. This is because most newly developed materials are used in Japan, such as: isotropic

nano-composite powder SPRAX[10], anisotropic Sm-Fe-N[9] and NdFeB (HDDR) powder [6]. New processing technology, new equipment, and new products are typically used in Japan first. The magnet price reduction in Japan was most significant in 2002 and 2003: it was 17.4% and 8%. The magnet price in Japan increased by 2.1% in 2004 and even more significantly by 27.2% in 2007. Prices in the USA, Europe, SEA and other also dropped significantly in 2002, and then rose gradually after that.

2 The price of MQ powder is the same all over the world; powder cost is a quarter to half of the magnet price. China's magnet price is the lowest, which places pressure on other magnet producers.

3 Magnet prices in Japan, USA, Europe, SEA and others are different, but they are at roughly the same level.

4 Magnet prices in China are only 50% of those in Japan.

5 The average price of magnets is midway between China's price and Japan's price (the average

price = total value / total output).

6 Since 2003 the magnet price in developed countries has remained the same or even risen, while the magnet price in China has continued to fall until 2007. Prices rose to $61/kg (an increase of 7%) in 2007, for the first time in a

Figure 7 Price of bonded NdFeB magnets in different regions

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 20080

20

40

60

80

100

120

140

160

180

China Japan USA Europe SEA Others Total

Pric

e ($

/kg)


The marvellous development of the rare earth magnet industry contd...

decade. Prices reached $62/kg in 2008.

7 Prices of rare earth materials have increased significantly since 2005, consequently the magnet price should have increase as well, which was reflected in magnet prices in developed countries, but not China. Consequently, China's bonded magnet industry is in an extremely difficult situation.

Magnet prices in China had decreased continuously since 1996 until 2007. They increased in 2007 by +7%. The prices of raw materials have increased sharply since 2000; prices of rare earth materials have increased sharply since 2005. Consequently, the price of bonded NdFeB should have increased as well, and this was reflected in the magnet prices in all countries except China. Obviously the price system in China is not as flexible as those in developed countries. Because the customers of magnets made in China are mostly overseas, the feedback of price is always delayed.

Current situation of Chinese bonded magnet manufacturers MQI has bought master alloy from China since the mid-90s. The ingot price was fixed at $5/kg until 2004 and the powder price was kept at $34/kg for a long time. It is easy to see how huge the profits from powder sales could be! However, MQI has announced that the powder price is changing and will be in the range $14-28/kg. In 2003 it was reported that Daido Steel, being a strategic partner of MQI, got MQ powder at a price of $22-24/kg. Up until now no one has got MQ powder at $14/kg. Such a price is only given to special strategic new customers. The price of master alloy increased to $6.5/kg by the end of 2005 due to the price rises of rare earth material. The price of rare earth material has risen significantly since July 2006, hence the price of master alloy increased as well: in October 2007 the price of alloy without Cobalt and with Cobalt was $12/kg and $16.5/kg respectively. The price of MQ powder jumped to $38-45/kg. Now the price of alloy has returned to $10/kg, but the price of MQ powder has remained around $34-38/kg, ie the alloy price is 32% of powder price, but it was 15% of powder price before 2004!

Once material prices are stable without inflation then, according to market rules, magnet prices should be reduced by 3-5% annually. But the MQ powder price of $34/kg has been fixed since the middle of the 90s, thus the profit from bonded magnet manufacture is very low – sometimes there is no profit at all. Due to patents MQI has kept its monopoly position in powder sales and

obtained huge profits, but at the same time a lot trouble has been shifted to its customers. Such a situation has caused considerable damage to the development of the bonded NdFeB magnet industry. Since the year 2000 the bonded NdFeB magnet industry has been in a dilemma: bonded magnet manufacturers have to face the high price of MQ powder on one hand, and the downward pressure of magnet price on the other. Some of the manufacturers, being aware of the gravity of such a problem, chose to give up or to find another business instead of bonded NdFeB magnet making. People have to choose a new powder source, other than MQI, in order to get rid of the control of MQI. It is the only exit for bonded NdFeB magnet manufacturers!

Jinbin Magnetronics Co, Ltd (JME) may serve as a good sample showing the dilemma of China's bonded magnet manufacturers. This company was established in 2000 and was located in the Tianjin Economic Development Area (TEDA). As a professional manufacturer of bonded rare earth magnets, JME specialised in producing compression

molded and injection plastic molded bonded NdFeB magnets. Annual output was up to 150 million pieces of bonded NdFeB magnet with various specifications. The company had a new building and was well-equipped with advanced production equipment and inspection instruments. Most importantly the company gathered together expertise with highly qualified technicians, a well-trained team for quality assurance and managing staff who are able to run the business following international rule. They have gone through considerable hardships to ensure their products satisfy the requests of customers within China and abroad. They received orders exceeding their capacity; in such a case they should surely further expand their business. But the clever manager found that something

was wrong: their sales value increased every year, but their profit was unchanged. What was the reason? Finally they found that MQ powder was the root cause, due to its monopoly high price. Anyone who uses MQ powder could gain no profit at all. In other words, they ran the business only for MQ, and not for themselves. Thus, there was no point in running such a business any more! Finally they took a drastic measure - to stop JME business completely, once the order for magnets received by the end of 2006 were finished. JME was closed in February 2007.

One year later, in April 2008, Ningbo Daiyoo Electronics Co, Ltd followed Jinbin (JME) and closed their business completely. They had to stop the business not due to lack of sales, nor due to financial difficulty in running. On the contrary, they had just received a big order from an overseas customer, since their product quality and delivery was to the full satisfaction of its customers. Daiyoo had to stop its operations because its shareholders felt that the profit of manufacturing bonded NdFeB magnets was too low. There was not any interest for them to keep such a

business any more!

It is a pity for the NdFeB bonded magnet industry in China indeed! Where is the exit? When will it develop as the sintered NdFeB magnet has?!

Although there are many difficulties, the market demand is there - it is still strong and expanding. When comparing with other countries, China is the only one whose output continuously rises. This shows the great vitality of the Chinese bonded magnet industry even when in a dilemma!

The output of bonded NdFeB has risen in China recently with an annual growth rate of +15%, although this is much lower than in 2006 (+47%). The output share of different regions during 1996-2008 is

Figure 8 Output share of bonded NdFeB magnets in different regions

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 20080%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

China Japan USA Europe SEA Others


Manufacturer Output Market Major products (ton/year) share Chengdu Galaxy Magnets Co, Ltd 940 40.2% HDD, CD/DVD, stepping motor, micro-motor

Shanghai Epson Magnetics Co, Ltd 710 30.3% HDD, CD/DVD Shengzhen Highmag Technology Ltd 100 4.4% CD/DVD, micro-motor Ningbo Yunsheng Bonded Magnets 110 4.7% Dongyang Innuovo Magnets Co, Ltd 160 6.8% George Electronics Co, Ltd 220 9.4% CD/DVD Jiangmen Powder Metallurgy Factory 40 1.7% Injection and compression, molded magnets

Shanghai Longci Technology Co 60 2.6% 2,340 tons in total

Table 2 Major bonded NdFeB magnet manufacturers in China (2008)

summarised in Figure 8. From this one can see the dramatic change in output share between China and the developed countries. In 1996 output share of China was only 3.3%, the same as Europe. The output of China exceeded SEA in 2002 and became number one in the world with 33% of the global total. The output share of China was 70% in 2008, which was much higher than any other. Since SEA is predominately Japanese overseas plants, the sum of SEA and Japan is essentially the output of Japan. Their output in 1996 was 77.2% of the global total, falling to 20% in 2008. In 2008 the output share of USA, Europe and other countries were 2.5%, 2.5% and 5%, respectively.

There are 20 or more bonded NdFeB magnet manufacturers; their output capacity and product quality vary considerably. The current status of the major bonded NdFeB magnet manufacturers in China is summarised in Table 2.

It is well known that in the mid-90s, the most famous bonded NdFeB magnet

manufacturers were Daido Steel, Seiko-Epson and TDK. Their products covered computers, office automation, home electronics and micro-motors. Their product volume was rather large and the quality was excellent, especially the accuracy in size and tolerance, which is hard to reach. With production cost increases the Japanese magnet manufacturers were forced to shift to South-East Asia and China: Daido Steel shifted to Thailand, Epson shifted to Shanghai, China, TDK opened a plant in China as well.Starting from the early 90s up to now the Chinese bonded NdFeB magnet industry underwent many experiences, and made much progress. Visits to many of the bonded NdFeB magnet manufacturers' plants has shown great progress in bonded magnet industry in China.

Galaxy Magnets Co, Ltd, located in the high-tech area of Chengdu city is

the pioneer of bonded NdFeB magnet manufacturing in China. In the early 90s, at the high tide of the opening policy, several young people had just left university and tried their talent in running a high-tech business. They decided to use the new NdFeB powders to make bonded NdFeB magnets. Through many years of painstaking efforts in difficult circumstances this plant was well developed since its establishment in 1993.

In 1999 the author accompanied Dr John Croat (inventor of rapidly solidified NdFeB powder) on a visit to Galaxy. Dr Croat noted that they use a quite simple machine to correct thickness tolerance very effectively and precisely. In 2000 a technical visiting delegation from Japan visited Galaxy. The production capacity and output volume made a deep impression on the visitors. They were surprised in watching how high performance magnets can be prepared by using a simple press with weighing and feeding performed by workers. The

quality control was guaranteed by a vast sea of people; the Japanese visitors said “if we did the same in Japan, the magnet price would be unbelievably high!”

Visiting Galaxy again in 2007, walking through both the old and new workshops, there was a marvellous change between them. In shining and spacious workshops a whole array of presses with newly equipped automatic feeding and discharging mechanisms were working automatically. There were very few workers among these presses. Now one person can control 5-8 presses. It is not the same as an old press, which should be operated by 2-3 workers!

Both product quality and output is much improved due to the automatisation of the forming process. The price of such automatic presses is only 1/10-1/15 of that of an imported one. Its performance and efficiency is higher since Galaxy designed

the automation mechanism based on its experiences in making magnets; they know which points are important and which are not. Thus the self-reconstructed automatic press is better than the imported fully automatic press.

Moreover, based on the experiences of many years hard work, Galaxy has been able to build up a most advanced coating line for HDD. Many customers after visiting said that this production line is the most advanced and largest one they have ever seen! The process gone through by Galaxy is just a development trace of the Chinese magnet industry. It gives evidence of how Galaxy has grown into the largest bonded NdFeB manufacturer in the world having started as a local private factory.

Development of the rare earth magnet industry in China and the developed countriesRare earth magnets in developed countries belong to the new materials used in high-

tech fields with special requirements, the price of which is rather high. Due to the unique requirements of the hardware used for preparation, such magnets are quite expensive. The development costs for the required software are also rather high. Thus, the rare earth magnet industry in developed countries is called the “Three Highs”, ie High investment, High output and High return. The rare earth magnet industry in developed countries is regarded with a special respect and enjoys certain preferential treatment. The situation in China is completely different to developed countries. The limited investment by Chinese magnet producers did not allow them to set high targets to start with, but they had to make do with what they had, ie they were unable to get expensive equipment to prepare magnets, so had to make do with what was available. Therefore, some changes in software were used to


remedy the weakness of the hardware. The most obvious example is the magnet forming process, where all the processing data are controlled precisely by fully automatic presses and the mold is made from special hardening alloy. In China a simple hydraulic press with a modified molding system is used. Weighing and feeding is performed manually. In this way bonded NdFeB magnets with high tolerances are made. The performance of these magnets is the same as those made by developed countries. With the expansion of production and markets, the hardware is under continuing modification, as seen in Galaxy. The newly reconstructed presses installed at Galaxy's new workshop are just one excellent example of this! The cost of one set of hardware is only 1/10-1/15 of the cost of an imported press. More importantly, the modified automatic press is much better than the imported one, both in efficiency and performance. In this way Chinese magnet manufacturers are able to provide magnets cheaper and better to customers worldwide.

Moreover, in order to improve corrosion resistance and the environmental stability of magnets, certain coating treatments are applied to bonded NdFeB magnets. Such coating treatments may be metallic electroplating, electrophoretic coating or spread coating, etc.Based on the customers' requests each magnet manufacturer has developed its own coating processes and equipment. Some Chinese NdFeB bonded magnet manufacturers have imported electrophoretic coating equipment, each of them have made their own improvements. Galaxy, based on its own experiences, designed and built up a completely new coating line for HDD. Its cleanliness reached a new height and its output capacity is the largest in the world. Most importantly its product price performance is the best. Based on the experience of many years, we strongly believe that as time goes on more advanced hardware will be developed and used by Chinese manufacturers. Its product level will be comparable with that made in developed countries. But its price performance will be among the best and lowest. This is the key to China's magnet industry position and its continuing progress in the global market.

Price – Quality – VolumeThe better the quality the higher the price, in other words the price of a product is directly proportional to its quality. However, price also depends on sales volume, the bigger the sales

Price Quality

volume the lower the price, ie price is inversely proportional to sales volume. The correlation between price, quality and sales volume can be expressed as triangle or pyramid shown in Figure 9.

A product of a high grade is located in the top of pyramid (zone 1). Its price and quality is high, but its volume is limited. The middle part (zone 2) means mid-price, its volume is much greater than the top. The price in the bottom part (zone 3) is much lower in comparison with the top,

and its volume is expanded significantly. Each company should be clear about their position in the market, ie the right location in this pyramid according to the requests of customers and the magnet product being provided. Then the business will be able to run successfully.

Sm-Co magnets occupied the majority of the high performance magnet market in the 80s; the magnet price was high and the market volume was limited at that time. Then NdFeB magnets arrived at a price which was comparable with SmCo but with better performance. NdFeB was used for computers, IT and electronics. With the popularisation of NdFeB the pressure for price reductions increased. The products of the “Three Highs” could not meet market demand. The products of China, however, following the philosophy of “Two Lows and One High”, ie Low investment, High output and Low profit, were just what was required by magnet customers all over the world. Consequently, the NdFeB output jump in China after 2002 was not accidental, but inevitable!Both the starting point and the target of the rare earth magnet industries in developed countries and in China are quite different. Obviously, the rare earth magnet industry in developed countries and in China will therefore take different paths. Consequently, the acceptability

The marvellous development of the rare earth magnet industry contd...

of their products to the global market is also quite different. In the early 80s, when the NdFeB magnet had just come out, the output of developed countries was dominant: in 1983 the output share of developed countries was 85% and China was 15%. 25 years later in 2008 a dramatic change has occurred: the output share of developed countries is 21.5% (Japan 19.8%, Europe 1.7%, USA 0%) and the output of China is 78.5%! The output of bonded NdFeB magnet is

similar: in 1996, the output share of developed countries was 96.8%, output share of China was only 3.2%. In 2008, the output share of developed countries has dropped to 30% and the share of China has reached 70%.It is fortunate that China did not build up her rare earth magnet industry following the “Three Highs” as in developed countries, but took a different path, following the philosophy of “Two Lows and One High”. This enables China to keep the price low and to meet the quality requests from customers. Thus, orders from all over the world

are now sent to China. Chinese magnet producers dream day and night of this situation. In fact, it is just return for their

continuing efforts over many years. Most importantly for Chinese magnet manufacturers is to keep in mind the gap between them and developed countries and to do their best to eliminate the technical gaps as soon as possible. They must renew their hardware and build up a well-trained technical team and quality control team, otherwise, the current favorable situation could disappear rapidly. The Chinese magnet industry should be strengthened further, so that it can stand in the storm of the market without damage. Conclusions

Now over 78% of the total global •output of NdFeB magnets is concentrated in China. China has the ability and duty to provide magnets cheaper and better, this includes sintered and bonded NdFeB magnets for customers worldwide.

With the progress of processing •technology, the cost of rapidly solidified NdFeB powder should be within two times of the alloy price. In 2008 the price of NdFeB alloy without Co was $11/kg. This means the price of MQ powder should be $24/kg or lower. This would be good news for bonded magnet manufacturers. The magnet output would be increased sharply by using such cheaper powder. The output of bonded NdFeB magnets would no longer pace up and down between three-

Figure 9 Correlation between price, quality and sales volume

←Marketvolume(Salesvolume)→


The Editor accepts no responsibility or liability in any way whatsoever for any statements made or opinions expressed in Magnews

five thousand tons; it could reach ten thousand tons very quickly!

All the patents belonging to MQI •which are free of Co content expired on 15 October 2008. And antitrust laws approved by the People’s Congress of China have been in operation since 1 August 2008. Both eventful matters bring hope for the Chinese bonded NdFeB magnet manufacturers, who have suffered the monopoly price of MQ powder for too long.

After the expiration of MQI’s patents •many new powder producers will have started production. It is most important that they provide cheaper and better powder. The IMT plant in Thailand, which started powder production in August, is worthy of note. Its products are as good as MQ. Its managing philosophy is different to that of MQI, and due to its low production costs and high productivity, its powder cost is lower.

Anisotropic NdFeB powder with •high performance will be put into mass production in the near future. Once they get the product to market, the high end market demand will be gradually changed, and therefore the application structure will also be changed.

REFERENCES[1] M Sagawa, S Fujimura, M Togawa, H

Yamamoto and Y Matsuura, J Appl Phys, 55, No 6, Part II A (1984) 2083

[2] J J Croat, J Appl, Phys 53, No 3 (1982), 2404

[3] Y Kaneko, Technological Evaluation and Application Trends of NdFeB Sintered Magnets in Japan, Proc of 18th Int Workshop on HPMA (Annecy, France, 2004), vol 1, p40-51

[4] S Hirosawa, Recent Developments and Future Perspectives of Nd-Fe-B Permanent Magnets for Automotive Applications, BM News, No 35, 2006, 3, 31, p135-154

[5] J J Croat, Technical Report of Magnequench, Delco Remy Divn of GM (1990)

[6] Y Honkura, Automotive Motor Innovation with Anisotropic Bonded Magnet – MAGFINE, Proc of 19th International Workshop on REPM and their Applications (Beijing, China, 30 August-2 September, 2006), p231-239

[7] Y Luo, Current Status of Global NdFeB Magnet Industry, BM News, No 33 (2005.3.31), p122-151

[8] Statistics Data on Bonded Magnets given by JABM Plan & Marketing Committee (2004,02,27,2005, 02, 24 and 2006,12, 07)

[9] K Ohmori, Progress of Sm-Fe-N Anisotropic Magnets, Proc of 19th International Workshop on REPM and their Applications (Beijing, China, 30 August – 2 September, 2006), p221-230

[10] S Ishigaki, S Hirosawa, Proc of Technical Frontier Symposium 2003 (Session D-3, Tokyo, April 17, 2003)

[11] Y Luo, Change and Development of Global NdFeB Magnet Industry, Electrical Engineering Monthly No 6 Serial No 97, 2008, p5-11

magnet manufactures have wished for.The commercialisation of anisotropic •

NdFeB powder would expand the range of applications for bonded NdFeB magnets. Sintered NdFeB may in some instances be replaced by anisotropic

With the mass production of both •isotropic and anisotropic NdFeB powder entering the market, we would have the good fortune to experience the flourishing bonded NdFeB magnet industry which

Abstract: Over the last few years there has been increasing interest in solar powered aircraft, which all use electric drives for the main propulsion system. These drives must combinelowmasswithveryhighefficiency.This work describes a permanent magnet machine drive, developed for the Zephyr solar plane, which broke the world endurance record in 2008. The machine uses 6% silicon steel laminations, which give very low iron loss, and a high pole number to minimize mass. The system has been developed to maximize efficiency,takingintoaccountbothpower electronic and motor losses.

Introduction Solar powered aircraft are being considered for many applications, but the most attractive proposition is to use them to perform many of the activities currently undertaken by satellites, but at a much lower cost [1-2]. The solar panels are flexible thin film, which makes up the skin of the wings. These panels supply power to the electric propulsion drives and a battery bank during daylight hours, and the batteries are used to supply the drives during the hours of darkness. The energy required to keep the plane aloft compared to the capability of the solar panels is finely balanced and is

Drive Train Solutions for Solar Powered UAVsProfessor Barrie Mecrow, University of Newcastle, School of Elec, Elec & Computer Engineering

only favorable if the batteries are very low in mass and the electric propulsion system is very efficient. Any small reduction in drive efficiency increases the energy storage requirement and hence the mass of batteries. It is therefore critical that the

propulsion drives exhibit high efficiency, combined with a low mass. This paper describes a demonstrator drive, which has been designed to produce very low losses, particularly at light load.The PlaneThere is now intense development of drives for solar powered UAVs [3-6], but generally these drives have yet to be used in an actual plane.

Zephyr is a solar powered plane developed by QinetiQ, shown being launched in figure 1. The electric propulsion system was designed at Newcastle University. The plane has a wingspan of 18 metres, but a mass of only 30kg. The air-frame is carbon

fibre, the wing coverings are solar arrays, and the battery banks lithium sulphur. There are two propellers, each supplied by a permanent magnet motor drive, capable of producing up to 3Nm of torque, and a maximum operating speed of 2500 revs/min. The plane operates in an energy neutral mode over each 24 hours: solar cells provide both propulsion power and charge batteries through the day and then the plane operates at low power overnight, supplied by the batteries. Efficiency must be

optimised for the overnight condition, with a speed of about 1500 revs/min and a torque of approximately 0.5Nm, corresponding to an output power of 80W. A mass penalty was employed in the design, corresponding to 10% loss of efficiency for every kg of mass.

Choice of driveThe work initiated with studies of various drive types, with the following conclusions:

Figure 1 Zephyr solar powered plane during launch

[This paper was presented at the UKMAG one day seminar More Electric Aircraft, held at the University of Bristol on 2 April 2009 - UKMAG members can access the full presentation on the Society’s website www.ukmagsoc.org]


Permanent magnet machines are by •far the most efficient, particularly in the relatively low size of machine of this application.

Gearboxes are a source of loss and •can be unreliable. A direct drive motor is both larger, heavier and has more losses than the geared alternative, but still offers increased efficiency overall, even when taking into account the increased mass penalty.

The machine should have a large •diameter to maximise the air-gap enclosed volume. This in turn reduces the shear stress requirement in the air-gap. The additional aerodynamic drag resulting from the larger motor must be taken into account, but this effect is not large.

Inverter and controller losses are •significant. Even the losses in the microcontroller can result in 2% less system efficiency at the critical night time condition. Care therefore needs to be taken in the choice and rating of all control electronic components.

The Propulsion Motor The need for minimum mass pushed the design towards a very high pole number with an outer rotor. As the pole number rose, the mass of laminations reduced due to small core backs, until above 36 poles the core back depth was constrained by mechanical strength requirements. However, as the pole number rose then so did the iron loss until it became as large as the winding loss on light load.

Even with 0.3mm silicon steels (M250-35A) the iron loss exceeded 4.0W at 1400 revs/min, giveing 4.5% loss of efficiency and so it was necessary to look for alternative materials. A very low loss lamination material was chosen, using 6% silicon steel of 0.1 mm thickness [1-2]. This material has only 0.3W/kg iron loss at 50Hz, 1 Tesla, but because of the high silicon content the material saturates earlier and so must be used at lower flux densities than more conventional lamination steels.

Figure 2 shows a 2D finite element model of the machine on no-load. The machine has the following features:(a) An outside diameter of 105.2mm and

an active axial length of 11.0 mm.(b) A peak lamination flux density

of 1.26T, which at an operating frequency of 400Hz corresponds to 9.2W/kg and a total iron loss of 1.47 Watts.

Test Results Figure 3 shows a close up of the demonstrator machine, including the

stator coils and rotor, whilst figure 4 shows the complete machine, along with the voltage fed inverter drive. Losses were evaluated as follows:

Total losses were estimated by •measuring output mechanical power and input electrical power.

No-load losses using “run-down” tests.•Conduction losses from measured •

resistance and rms currents.

Total system losses of under 8W were measured at low load, corresponding to overall system efficiencies of over 90%. The machine is torque dense: it can produce over 5.0Nm per kg at thermal limit.

ConclusionsThe propulsion efficiency of solar powered planes which have under 1kW of propulsion power can be maximized by using direct drive permanent magnet machines. Iron loss can be ruinous unless special measures are taken to minimize it: in this case through the use of 0.1 mm 6.5% silicon steel laminations.

AcknowledgementThe authors would like to thank QinetiQ for permission to publish this paper.

References[1] B Mecrow, J Bennett, A GJack, D

J Atkinson, A Freeman, Very High Efficiency Drives for Solar Powered Unmanned Aircraft, Proceedings on International Conference on Electrical Machines, Vilamoura, Portugal, 6-9 September 2008

[2] High Altitude, Long Endurance UAV – Zephyr, http://www.qinetiq.com/home/defence/defence_solutions/aerospace/unmanned_air_systems/uav.html

[3] J F Eastham, F Profumo, A Tenconi, R Hill-Cottingham, P Coles and G Gianolio, Novel Axial Flux Machine for Aircraft Drive: Design and Modelling, IEEE Trans Magnetics, Vol 38, No5,

September 2002, pp3003-5[4] Hill-Cottingham, R J; Coles, P C;

Eastham, J F; Profumo, F; Tenconi, A; Gianolio, G, Multi-Disc Axial Flux Stratospheric Aircraft Propeller Drive, 36th Annual IEEE IAS Meeting, 30 Sept-4 Oct. 2001, vol 3, Page(s):1634 – 1639

[5] P Ragot, M Markovic and Y Perriard, Optimisation of Electric Motor for a Solar Airplane Application, IEE Trans on Industry Applications, Vol 42, No 4, July/August 2006, pp1053-1061

[6] P Ragot, P Germano, M Markovic and Y Perriard, Brushless DC Motor for a Solar Airplane Application: Comparison between Simulations and Measurements, IEEE Industry Applications Society Annual Meeting, 5-9 Oct. 2008, pp 1-6

[7] JFE Steel Corporation data sheet for JFE Super Core JNEX900.J.http://www.jfe-steel.co.jp/en/products/electrical/catalog/f2e-001.pdf

[8] Namikawa, M; Ninomiya, H; Tanaka, Y; Takada, Y, Magnetic Properties of 6.5% Silicon Steel Sheets Under PWM Voltage Excitation”, IEEE Transactions Magnetics, Volume 34, Issue 4 Part 1, July 1998 Page(s):1183 - 1185

Prof Barrie Mecrow, University of Newcastle, School of Elec, Elec & Comp Engineering

Drive Train Solutions for Solar Powered UAVs contd...

Figure 2 Finite element analysis of demonstrator machine

Figure 3 Close up of propulsion motor and integrated drive

Figure 4 The propulsion motor


UKMAG forthcoming seminars for 200928 April 2009: Cutting Costs by Optimised Use of Materials, at TRW Conekt, Solihull

Buyers and suppliers are facing the twin challenges of the dramatically increased price of key materials for electromagnetic devices (such as Steel, Copper, Cobalt and Rare-Earth metals) and a global economic crisis. Costs can be saved by sourcing materials which have only the minimum properties and quality control required, and selecting the suppliers best matched to providing them. This can be achieved by:• analysing device designs to identify minimum material requirements• measuring the properties of materials which are fundamental to a product’s performance (rather than only “standard measurements)• optimising device designs to minimise use of expensive materials• assessing suppliers’ ability to minimise cost of their materials by reducing the content of expensive elements, and avoiding expensive processes, whilst guaranteeing properties which are just good enough• developing quality control methods which make it safe to use minimum cost materials.This seminar aims to bring together buyers, suppliers and designers to show how the above approach can succeed.

The global search for better energy efficiency in our daily lives is a constant demand from today’s markets. Advanced soft and hard magnetic materials offer the means to fulfil these demands, in markets as diverse as aerospace, automotive, installation technology and renewable energy. This seminar will highlight recent advances in material properties and processing technology, together with application based developments. For Soft magnetic materials this will include a particular focus on crystalline CoFe, amorphous and nanocrystalline alloys, and for hard magnetic materials the focus will be on the sintered Nd-Fe-B and Sm-Co magnet compositions. Application areas could be in developing technologies such as hybrid electric vehicles, wind energy, electronic energy metering, sensors, and the more electric aircraft.The venue for this event will be the Tulip Inn in Hanau, located less than 30 minutes by taxi from Frankfurt am Main International Airport. Frankfurt is well served with many direct flights from the UK and Continental airports. The VACUUMSCHMELZE head office and main works is located only a five minute walk from the hotel, and a factory tour is planned for Tuesday afternoon, 13 October.Further details and programme to be announced shortly

12-13 October 2009: Advanced Magnetic Materials and Their Applications, in Hanau, GermanyThis event will be hosted and co-sponsored by VACUUMSCHMELZE GmbH & Co KG, Germany, and will be held at the Tulip Inn, Kurt-Blaum-Platz 6, 63450 Hanau, Germany

Chairman: Dr Chris Maddison, Cummins Generator Technologiesfrom 0900 REGISTRATION/COFFEE1000 WELCOME/INTRODUCTION1015 Design Considerations for the Efficient Use of Magnetic

Components, Dr Mark Harradine, Mechetronics Limited1045 Enhancing Cost Performance of NdFeB Magnets

through the Grain Boundary Diffusion Process, Bob Buettner, Shin-Etsu Magnetics Inc, Germany

1115 Optimised Material Selection by Integrating Magnetic Materials and Design Analysis Expertise, Harvey Smith and Graham Kemp, TRW Conekt

1145 Improved Cost and Magnetic Function in Components used in Automotive Actuators, John Taylor, SG Magnets Limited

1215 LUNCH/EXHIBITION

Chairman: Graham Kemp, TRW Conekt 1230 SUPPLIER EXHIBITIONS (plus TRW Laboratory Visits)1345 Cost-Effective Motor Design using Bonded NdFeB Magnets,

Dr Nimit Sheth, Magnequench Neo Powders Pte Limited, Singapore

1415 Optimised Material Selection and Design for Laminations, Dr Gwynne Johnston, Director of Technology, Tempel Steel Company

1445 TEA/COFFEE1515 Rare Earth Permanent Magnet Raw Materials Supply, David Kennedy, Great Western Minerals Group1545 Soft Magnetic Composite in Optimised Machine Design,

Dr Glynn Atkinson, University of Newcastle-upon-Tyne, School of Elec, Elec & Comp Eng

1615 END

24 June 2009: Superconductivity Applications, at University of Birmingham Superconductivity was discovered in 1911 by Heike Kamerlingh Onnes. However, it was not until the 1960s that superconducting electromagnets (based on Nb-Ti with a critical temperature, Tc ~ 20K) were commercially available. These types of superconductors became known as “low Tc” after the discovery, in 1986, of the cuprate based “high Tc” superconductors with Tc > 90K. Today, the majority of applications are still in the use of superconductors to generate high magnetic fields for MRI, scientific experiments etc, and mostly employ low Tc materials. The aim of this seminar is to review these applications and to present emerging and future applications of low and high Tc materials, including fault current limiters, trapped field devices, energy storage, motors etc. Presentations so far include:Superconducting Fault Current Limiters using Wire-Form MgB2, Professor Sandy Smith, University of Manchester, School of Electrical and Electronic Engineering Coated Conductor Cylinders - What’s the Magnetic Attraction?, Dr Eamonn Maher, 3-Cs Ltd Microwave Applications of High Temperature Superconductors, Professor Mike Lancaster, University of Birmingham, School of Electronic, Electrical and Computer Engineering Finite Element Simulation of Superconducting Magnets: Ramping, Magnetisation and Quench, John Simkin, Cobham Technical Services – Vector Fields SoftwareChallenges Facing the Successful Application of High Temperature Superconductors to Rotating Machinery, Ruben Fair, Advanced Technology Group, Converteam UK Further details and programme to be announced shortly


November 2009: Instruments: Measurements and Standards

200915-16 April Magnetics Conference 2009, Chicago, USA: www.infoweb-

com.com28 April UKMAG seminar Cutting Costs by Optimised Use of Materials,

at TRW Conekt, Solihull: www.ukmagsoc.org3-6 May IEEE IEMDC 2009, Intl Electrical Machines & Drives Conference,

Miami, Florida: www.iemdc2009.org 4-8 May Intermag2009 Conference, Sacramento, Calif, USA: www.inter-

magconference.com/intermag2009 5-7 May CWIEME Berlin 2009, Berlin, Germany: www.coilwindingex-

po.com, [email protected] May EMF2009, 8th Int Symposium on Electric & Magnetic Fields

from Numerical Models to Industrial Applications, Mondovi, Italy: www.aimontefiore.org/emf2009/

11-12 June EMC Europe Workshop - Materials in EMC Applications, Ath-ens, Greece: http://emceurope2009.iccs.gr

22-24 June ISTET09, 15th Int Symposium on Theoretical Electrical Engi-neering, Lubeck, Germany: www.istet09.de

24 June UKMAG seminar Superconductivity Applications, at Univer-sity of Birmingham: www.ukmagsoc.org

22-26 June European Powder Metallurgy Association (EPMA) Summer School, Kosice, Slovakia: qqq.epma.com/summerschool

8-11 July RoPM2009, 4th Int Conf on Powder Metallurgy, Craiova, Romania: www.sim.utcluj.ro/RoPM2009

27-31 July ICCM17, 17th Int Conf on Composite Materials, Edinburgh: www.iccm17.org

6-9 Sept SMM19, Soft Magnetic Materials Conference,Torino, Italy: www.smm19.eu, [email protected]

7-10 Sept Euromat2009, Hard & Soft Magnets, Glasgow: www.euro-mat2009.fems.eu

8-10 Sept EPE2009, 13th Int European Power Electronics Conf & Ex-hibition, Barcelona, Spain : www.epe2009.com

10-12 Sept ISEF09, Int Symposium on Electromagnetic Fields in Me-chatronics, Electrical and Electronic Engineering, Arras, France: www.isee.fr/isef09/

13-17 Sept EUCAS 2009, 9th European Conference on Applied Supercon-ductivity, iDresden, Germany: www.eucas2009.eu/eucas2009

12-13 Oct UKMAG seminar Advanced Magnetic Materials & their Ap-plications, at Hanau, Germany [hosted & co-sponsored by Vacuumschmelze GmbH, Germany]: www.ukmagsoc.org

Dates for your diary

UK Magnetics Society, Grove Business Centre, Grove Technology Park, Wantage, Oxon OX12 9FA, UKtel: +44 (0)1235 770652 fax: +44 (0)1235 772295 email: [email protected] www.ukmagsoc.org

Editor-Magnews: Jane Ward, UK Magnetics SocietyEditorial Committee: Chris Maddison, Cummins Generator Technologies Stuart Eaton, QinetiQ Limited Graham Kemp, TRW Conekt

You are invited to send details of appropriate events for in-clusion in Dates for your Diary in future issues of Magnews, for the interest and benefit of Magnews readers

13-14 Oct EMCUK 2009, EMC Exhibition & Conference (partnered by IET), Newbury: www.emcuk.co.uk

November UKMAG seminar Distributed Generation, at Areva T&D Tech-nology Centre, Stafford: www.ukmagsoc.org

November UKMAG seminar Instruments: Measurements and Standards: www.ukmagsoc.org

16-18 Nov EHE09, Int Conf on Electromagnetic Fields, Health & Environ-ment, Sao Paulo, Brazil: www.ehe09.usp.br [deadline for pa-pers 5 May 09]

22-26 Nov Compumag 2009, Florianopolis,Brazil: www.compumag2009.com24-26 Nov CWIEME Mumbai 2009, Mumbai, India: info-india@coilwind-

ingexpo.comDec UKMAG 23rd Ewing Event: details TBC, www.ukmagsoc.org

201017-21 Jan Joint MMM/Intermag Conference, Sacramento, USA: www.

magnetism.org/futureconf.htmlTBC 1&2DM, 11th Int Workshop on 1&2 Dimensional Magnetic

Measurement of Testing, Oita, Japan: details TBCDec UKMAG 24th Ewing Event: details TBC, www.ukmagsoc.org

201112-15 July Compumag 2011, Sydney, Australia: details TBCDec UKMAG 25th Ewing Event: details TBC, www.ukmagsoc.org

First invitation to bid for COMPUMAG 2013A formal invitation to bid to organise COMPUMAG 2013, preferably in Europe, will be issued later and published in the July issue of the ICS (International Compumag Society) newsletter. This announcement is a preliminary invitation. Interested groups and institutions will be invited to first communicate to the Secretary an intention to submit and then prepare the bid in accordance with Article VII of the Bye-Laws and following the special guidelines. All details will be given in the July issue of ICS. A decision about the conference venue and the group which is awarded the organisation will be made at COMPUMAG 2009 in Florianopolis, Brazil, 22-26 November 2009. www.compumag/co uk

Further details and programmes for the above events will appear on the Society’s website when finalised: www.ukmagsoc.org

December 2009: 23rd Ewing Event, London

Do you have an idea for a future UKMAG seminar?The UK Magnetics Society endeavours to organise seminars that will appeal to our membership. If you have any ideas of future topics for seminars, have a subject, or your latest product or research developments that you want to present on, then please get in touch with the Secretariat. We would like to hear your suggestions. Please contact [email protected]

UKMAG forthcoming seminars for 2009 contd...

November 2009: Distributed Generation, at AREVA T&D Technology Centre, Stafford


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