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Contents:

Topics: What’s New in the World of Superconductivity
Feature Article: Reporting on the 2015 Forum on Superconductivity Technology
Trends- Current Status of Superconductivity Development in Korea- Current Status of Superconducting Power Equipment in Japan and their R&D Prospects- The Current Status and Prospects of RE-based Superconducting Wire Development inJapan- Current Status of Superconductor-based Equipment Development Undertaken by
Toshiba- Mitsubishi Electric – Challenges in Manufacturing Superconductor-based Products- High Temperature Superconducting Technology Development at Furukawa Electric

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Top of Superconductivity Web21: http://www.istec.or.jp/web21/web21-E.html
This work was subsidized by JKA using promotion funds fromKEIRIN RACE
http://ringring-keirin.jp

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What’s New in the World of Superconductivity초전도 뉴스 –세계의 동향超电导新闻-世界的动向-chāo diàn dǎo xīnwén

- shìjiè de dòngxiàng-

Yutaka Yamada, Principal Research Fellow
Superconductivity Research Laboratory, ISTEC★News sources and related areas in this issue►Power Application

전력응용电力应用 [diànlì yìngyòng]HTS Transformer with Low Loss Roebel Conductor”
University of Wellington (20 May, 2015)
The Victoria University of Wellington along with industry consortia, have demonstrated experimentally forthe first time that HTS power transformers can significantly reduce energy losses compared to conventionaltransformers, thereby demonstrating their efficiency and reliability, along with the potential ofsuperconducting transformers to deliver real value in transmission grids.
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HTS transformers are smaller in size and lighter than conventional transformers, using liquid nitrogen forcooling and insulation instead of transformer oil, thereby eliminating fire and environmental hazards. With
funding from the New Zealand Ministry of Business, Innovation and Employment and industry consortia,
the researchers teamed up with Callaghan Innovation, which managed the engineering, assembly andtesting, Fabrum Solutions for the cryostat engineering, local utility companies Vector and Northpower,
Wilson Transformer Company, ETEL Transformers and GCS. Wilson Transformer Company, based in
Melbourne, Australia, contributed design and manufacturing expertise to the project and constructed thetransformer’s steel core.
The HTS transformer is currently undergoing factory testing in Christchurch, where initial trials show that it
has successfully handled a current capacity of 1390 A. Also, measurements confirm the energy losses arehalf those of a conventional transformer. Further tests of the transformer involve mimicking real-world
loading profiles for extended periods. Crucial to the transformer’s success is the use of low ac-loss Roebel
cable on the high-current secondary winding, designed and manufactured in New Zealand by GCS Ltd. Dr
Nick Long, a senior principal scientist with the Robinson Research Institute states that, “GCS Ltd has
manufactured its own unique HTS Roebel cable.” Professor Bob Buckley, Director of the Robinson
Research Institute, cites the close working relationship with a number of industry partners that have allowed
the team to rapidly overcome technical hurdles.
The researchers are now looking to assemble a team for the next phase of the project, which will develop
the first commercial prototype 2G HTS transformer.
Source: ”Transforming power transmission worldwide”(20 May, 2015) Press Release
http://www.victoria.ac.nz/robinson/about/news
Contact: Bob Buckley, bob.buckley@vuw.ac.nz►Medical Application 의료응용 医疗应用 [yīliáo yìngyòng]Ultra-High-Field 7-Tesla MRINational Institute for Physiological Sciences (26 May, 2016)
The National Institute for Physiological Sciences (NIPS), has installed an ultra-high-field 7 T MRI system.
The system has a two- to five-fold greater magnetic field strength than standard hospital MRIs, providing
greater biological signal sensitivity and more precise images with higher contrast. The MRI system employs
a novel type of superconducting magnet - an actively shielded magnet, a first of its kind to be used forhuman research in Japan. This new type of magnet reduces the emission of magnetic energy, thereby
contributing to both safety and measurement accuracy. There are around 50 ultra-high-field 7 T MRI
machines are in operation around the world, which includes three in Japan.
The scanner will enable high-precision visual data about the anatomy and function of the brain in a
non-invasive manner, expanding the horizon of in vivo human research. It is anticipated that this advanced
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MRI system will enable 100 microns analysis of cerebral microstructure, visualization of important
microvessels, and three-dimensional reconstruction of complex neuronal networks.
NIPS has launched the Interactive Research Promotion Committee, which includes representatives fromother ultra-high-field MRI research centers in Japan: Iwate Medical University Institute for Biomedical
Sciences, Niigata University Brain Research Institute, Kyoto University Human Brain Research Center,
Center for Information and Neural Networks of the National Institute of Information and Communications
Technology, RIKEN Brain Science Institute, and National Institute for Environmental Studies. NIPS aims tostrengthen the technical foundation for ultra-high-field MRI research, nurture interdisciplinary research in
MRI, promote international collaborations and accelerate joint activities with national and international
colleges and research organizations.
Source: ”NIPS Introduces An Ultra-High-Field 7-Tesla Magnetic Resonance Imaging (MRI) System” (26May, 2015) Press Release
http://www.nips.ac.jp/eng/release/2015/05/mri_1.html
Public Relations, pub-adm@nips.ac.jp

Ultra-low-field MRI
Los Alamos National Laboratory (1 Jun, 2015)
Researchers at Los Alamos National Laboratory are developing an ultra-low-field Magnetic ResonanceImaging (MRI) system that could be lightweight and low-power enough to be used on the battlefield and infield hospitals in the Third World. The consensus amongst doctors who routinely work in the Third World
have reported that such lightweight MRI systems would be extremely valuable in treating pediatric brain
disorders and other serious diseases in children. Mainstream hospital-based MRI devices are large andexpensive to operate, requiring considerable infrastructure such as liquid nitrogen and helium.
The team at Los Alamos investigated the use of whether ultra-low magnetic fields produced using SQUIDs
would produce images of sufficient quality. The main stumbling block of SQUIDs has been signal
interference. The team's first-generation MRI had to be built in a large metal housing in order to shield itfrom interference.
The Los Alamos team is currently working in an open environment system without the large metal housing.
Instead, they are using a series of wire coils that surround the MRI system to compensate for the Earth’s
magnetic field. Team leader, Espy, stated, "The new system indicates that, with additional development,these systems could be relatively easy and inexpensive to deploy."Source: ”Los Alamos is developing powerful medical tool”(1 June, 2015) Publications
https://www.lanl.gov/discover/publications/connections/2015-06/science-portable-mri-aid-soldiers.php
Contact: Editor, ute@lanl.gov

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Superconducting Synchrocyclotron Accelerator for Proton Therapy
Mevion Medical Systems (29 Jun, 2015)
Mevion Medical Systems has announced the delivery of the superconducting synchrocyclotron accelerator
for its MEVION S250 proton therapy system, which is being installed at University Hospitals (UH)
Seidman Cancer Center and UH Rainbow Babies & Children’s Hospital in Cleveland. It is expected to
begin treating cancer patients in the spring of 2016.This is the sixth accelerator delivery for Mevion, theinnovator behind the world’s most efficient and cost-effective high-precision proton therapy system.
Proton therapy is an advanced form of radiation therapy targeting cancer cells more directly, thus making it
ideal for treating patients with cancer in sensitive locations such as near the heart or brain. Traditional proton
therapy systems cost hundreds of millions of dollars to build and are much larger in size. The MEVION
S250 offers effective and efficient treatment without the complexity of traditional systems. In addition, thecapital costs and the operating costs are significantly less since the system uses less space, less staff andless energy than other proton systems.
Source: ”Mevion Medical Systems Delivers Proton Accelerator to Seidman Cancer Center at University
Hospitals” (29 Jun, 2015) Latest News
http://www.mevion.com/news/1093-mevion-medical-systems-delivers-proton-accelerator-to-seidman-cancer-center-at-university-hospitalsContact: http://www.mevion.com/contact-us►Basics기초 基础[jīchǔ]High Tc , 60 K, of FeSe FilmTohoku University (2 Jun, 2015)
A research team based at Tohoku University led by Prof. Takashi Takahashi (WPI-AIMR) and Asst. Prof.
Kosuke Nakayama (Dept. of Physics), has succeeded in fabricating an atomically thin, iron-based
high-temperature superconductor film of FeSe with a superconducting transition temperature (Tc) of up to
60 K (-213 °C). The same team has also established a method to tune the Tc. The research results were
published in Nature Materials on June 1, 2015.
Superconductors offer promise in the next-generation advanced electronic devices, because of uniquequantum effects that offer energy-saving advantages and ultrahigh-speed processing. The application ofsuperconducting devices has been hampered by the necessity of requiring a large and expensive coolingsystem due to the low Tc of conventional superconductors. While the Tc of bulk FeSe is only 8 K, anultra-thin film coating with thickness of between one and twenty monolayers points towards a material withhigher-Tc. The FeSe films have been fabricated by molecular-beam-epitaxy (MBE) and the electronic
structure investigated using angle-resolved photoemission spectroscopy (ARPES). ARPES enabled theresearchers to observe the opening of a superconducting gap at low temperature, which is direct evidenceof the emergence of superconductivity in the FeSe films, and estimating the Tc from the gap-closing in a
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monolayer film to be above 60 K, around 8 times higher than bulk Tc of FeSe.
The research team has also discovered novel methods to deposit alkali atoms onto the films and thereby
control the electron density, succeeding in converting non-superconducting multilayer FeSe films into
high-Tc superconductors with Tc as high as ~50 K. While the Tc achieved in this study is still lower than thatof the cuprate high- Tc superconductors, it exceeds the record of other "high- Tc superconductors" such as
fullerene (C60) superconductors and MgB2.
Research to further increase Tc by changing the number of atomic layers, the amount of doped electrons
and the substrate type is expected to begin since the Tc of 50-60 K achieved in the present study is highenough to keep the superconducting state by using a closed-cycle-gas-type cooling system without liquid
helium.
This work was supported by grants from the Japan Society for the Promotion of Science (JSPS) andJapan's Ministry of Education, Culture, Sports, Science and Technology (MEXT).
Source: ”High-temperature Superconductivity in Atomically Thin Films”(2 Jun, 2015) Press Release
https://www.tohoku.ac.jp/en/news/research/news20150602_1.html
Contact: Takashi Takahashi, t.takahashi@arpes.phys.tohoku.ac.jp

High Tc of 49 K in Pressurized FeSe
Okayama University (June, 2015)
Yoshihiro Kubozono and his research team at Okayama University have discovered that materials placed
under high pressure can induce significantly greater superconducting transition temperatures (Tc).
Kubozono applied high-pressure to ammoniated Cs doped FeSe ((NH3)yCs0.4FeSe)) material andmeasured the the resistance under pressures of between 0 – 41 GPa.
Metal-intercalated FeSe’s fabricated using liquid ammonia technique exhibited very high Tc of 30 - 45 K.
The Tc increased rapidly with changes of FeSe plane spacing (d), suggesting that increases in
two-dimensionality increases Tc. Previously, the recognized limit of Tc was 45 K, but a study by Sun et al.
measured a Tc of 48 K in pressure-induced high-Tc superconducting phase for two metal doped FeSematerials (Tl0.6Rb0.4Fe1.67Se2 and K0.8Fe1.7Se2). However, such characteristics are rarely reported becauseof the difficulty of conducting experiments to validate this.
The Tc of (NH3)yCs0.4FeSe (31K at ambient pressure) decreased gradually with increases in pressure, but
no superconductivity was measured down to 4.2 K at 11 – 13 GPa. Above 13 GPa, the superconductivity
rematerialized and a U-shape pressure-dependence of Tc was found between 15 - 41 GPa. The maximum
Tc reached 49 K at 21 GPa.
Source: ”High-Tc superconductivity found under high pressure”(Jun, 2015) Research Highlights Okayama Univ. e-Bulltin
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http://www.okayama-u.ac.jp/user/kouhou/ebulletin/research_highlights/vol11/highlights_003.html

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Feature Article: Reporting on the 2015 Forum on Superconductivity
Technology Trends-Current Status of Superconductivity Development in Korea
Minwon Park, Professor
Changwon National University, Korea
In 2001, Korea saw the unveiling of power
equipment exploiting high temperature
superconducting wires, e.g. the DAPAS
program. More than 10 billion yen has so
far been invested in R&D funding over the
past ten years, with more than 15 billion
yen coming from industries over the same
period. The research has continuallyfocused on themes related to hightemperature
superconducting
power
cables, superconducting transformers, fault
current limiters and superconducting rotors.
Around 1/3 of the funding has been
invested in the development of theFig.1 DC-Superconducting cable in Jeju Islandnext-generationhightemperature
superconducting wires. Here, hightemperature
superconducting
power
cables have been demonstrated in 23 kV
AC and 80 kV DC grids even though their
future prospects may change over the nextten years. Additional trials in 154 kV AC
grids are planned for later this year. Hightemperature superconducting transformers
have issues with AC losses and offer noclear efficiency advantages. Consequently,
it has proved difficult to find corporations tofund R&D activities, which has hampered
their practical realization. The R&D focus
involvinghightemperature
superconducting fault current limiters has
Fig.2 Superconducting generator for 12 MW wind turbine
solely been for demonstration studies in
154 kV grids. Their installation in an actual grid is anticipated sometime in 2016. Whilst research in hightemperature superconducting rotors is still ongoing, the author expects quite a few issues that remain to beresolved before they can be realized for practical applications.
SUNAM and the Korea Electro-technology Research Institute have led R&D studies on high temperature
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superconducting wires. Their track records and achievements until now have been exceptional, and been
responsible for the supply of the cheapest next-generation high temperature superconducting wires
worldwide. The DAPAS program has been instrumental in their achievements, thereby highlighting theimportance of national R&D investment for the industrialization of technology. 2011 saw the end of the
DAPAS program with commercialized research outcomes being high temperature superconducting power
cables and superconducting wires, whilst other research studies remained midway through development. It
is always challenging to expect that all research themes will produce practical and commercial success,however, the author is delighted since 1/3 of the research outcomes have become closer towards
industrialization.
Ongoing programs in 2015 include, developments of high temperature superconducting cables connected
to 154 kV AC grids, 1500 A-class DC reactors, 12 MW-class high temperature superconducting wind power
generators and high temperature DC-induction heaters. New R&D studies for the next-generation hightemperature superconducting wires and MgB2 wires have been launched. The developments are fundedby organizations that mainly include KEPCO, which has a strong focus on superconductivity and ispursuing a project program aiming for their industrialization. (Figure 1 and 2)

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Feature Article: Reporting on the 2015 Forum on Superconductivity
Technology Trends-Current Status of Superconducting Power Equipment in Japan and their
R&D Prospects
Hiroyuki Ohsaki, Professor
Graduate School of Frontier Sciences
The University of Tokyo
The current development of superconducting power equipment technology has been mainly initiated by
NEDO projects, and dedicated towards the development of power turbine generators, SMES, flywheel
energy storage systems, power cables, fault current limiters and transformers. A demonstration project(2007-2013) involving a high temperature superconducting cable with 66 kV 200 MVA-class characteristics(about 240 m-long), was installed at the Asahi sub-station of Tokyo Electric Power Company, completing a
one-year trial of actual power grid connection. Three-year demonstration plans that began in 2014 are now
progressing and focused on studies to verify safety/reliability of the next generation transmission systems.
The development of 275 kV high voltage cables utilizing Y-based coated conductors have been undertaken
and long-term current load tests performed. Demonstration trials involving superconducting fault current
limiters have been actively pursued overseas, which is in stark contrast to developments in Japan.
Amongst the ALCA program led by JST, R&D studies of liquid hydrogen cooled superconducting
equipment and its related technology is advancing. Additionally, the development of superconducting wind
power generators greater than 10 MW-class for offshore wind farms has focused on solving issues that
include their low speed characteristics, high torques and their large footprints. These studies are dedicatedtowards high power output, direct drive synchronous machines. FS has progressed by NEDO projects
undertaken in 2013 and 2014.
From the summer of 2013, superconducting maglev trains operating with commercial carriages resumed
test runs at the 42.8 km-long Yamanashi test track, which has undergone revision upgrades and has also
been extended. A speed of 603 km/h was recorded on 21st April 2015, beating the previous world speedrecord for a train. Commercial operations of the Chuo Shinkansen superconducting maglev line between
Tokyo and Nagoya are planned for 2027. Ongoing R&D led by the JST S-innovation program relates tosuperconducting DC-cable applications for the DC feeder system, its aims being the suppression of feeder
voltage drops, improvement of regenerative ratios, reduction of sub-station capacities etc. Experimental test
runs at the Railway Technical Research Institute have taken place.
With regards to ship propulsion motors, in 2013, Kawasaki Heavy Industries developed a 3 MW-classsuperconducting ship propulsion motor aimed at a mid-size ship. A research group in Kyoto University and
Sumitomo Electric is currently undertaking the development for a superconducting motor for electricvehicles.
Recently, the focus has been on heavy-ion cancer therapies, which have built up a considerable track

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record. The development of a rotating gantry has been undertaken to reduce the time to ascertain theradiation focus and thus improve the treatment plan. NbTi superconducting magnets were able to realize acompact/lightweight, rotating gantry. A project for high temperature superconducting fundamental
technology, led by the Ministry of Economy, Trade and Industry launched in 2013. Its objectives are todevelop the potential of high temperature superconducting coil technology and for this technology to be
applicable for clinic-use MRI and heavy-ion medical accelerator systems. From 2015, this project will be ledby the Japan Agency for Medical Research and Development (AMED), and plans are to complete thiswithin one year.
We cannot say whether Japan has reached a stage where high temperature superconducting technology is
being practically realized in equipment applications. Foreseeing the economic benefits is necessary in orderto validate the superior fundamental performance characteristics attained by high temperature
superconducting equipment, in addition to demonstrating its reliability and benefits of system upkeep. To
this effect, it is therefore important to establish a fundamental technology for the stable supply of low-costhigh-performance wires, coiling technology, cable technology, rotor technology etc.

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Feature Article: Reporting on the 2015 Forum on Superconductivity
Technology Trends-The Current Status and Prospects of RE-based Superconducting Wire
Development in Japan
Teruo Izumi, Deputy Director General
SRL/ISTEC

History of R&D for Coated Conductors in the World

RE-based superconducting wires are anticipated in the deployment of an array of potential applications that
includes power applications, because of their superior superconductivity and mechanical characteristics.
However, difficulties in the manufacturing process to replicate these superior characteristics have delayed
their deployment in contrast to Bi-based superconducting wires. A national collaborative project involving
ISTEC, universities and wire manufacturers, have led a full-scale development project involving RE-based
wires, which has seen recent commercial success and has resulted in further development of equipment
employing such wires. The author provides a brief historical account, the latest progress and future
prospects of RE-based superconducting wire development.

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All three superconducting crystal axis need to be aligned in order to realize the superior characteristics
afforded by RE-based superconducting wires. An IBAD-substrate developed by Fujikura exhibits highorientation because of the orientation of the buffer layer, which even today, forms the mainstream ofworldwide RE-based superconducting wires. Later, ISTEC discovered the self-organization of CeO2, which
improves orientation and has significantly contributed towards the advancement involving the substrate.
Additionally, several methods including PLD, MOD and MOCVD are presently employed for the fabricationof superconducting layers, exploiting the advantageous characteristics of each of these methods.
For long-wire manufacturing, national projects in both Japan and USA have led the world since 2000. Ic x L
values has progressed remarkably over the past 10 years. This has spurred SuNAM in Korea who havecaught up with the leaders and is currently included as one of the major wire manufacturers together withJapan and USA. Whilst single-length 1000 m wires have already been realized, wires with Ic characteristics
exceeding 500 A/cm@77 K, s.f. are currently being manufactured.
Apart from Ic x L characteristics, equipment specifications to meet functional improvements such asenhanced in-field Ic properties and to reduce AC losses are now necessary. Such developments have been
actively undertaken by projects conducted over the past several years, namely the development of
yttrium-based superconducting power equipment technology and ongoing studies of high temperature
superconducting fundamental coil technology. BaHfO3 artificial pinning centers in PLD superconducting
films have proved effective in demonstrating the superior in-field characteristics of (example: 569A/cm
width@65 K, 3 T B//c) for EuBCO+BHO films. Regarding the reduction of AC losses, the progress ofscribing technology has seen the world’s first success in a 10-filament scribing process of 100 m (5 mmw)
long-wire. Reduced AC-losses in a coiled shape have been also confirmed.
These research outcomes have recently advanced equipment development that includes MRIs, heavy-ion
medical accelerators and rotors, in addition to power applications such as transmission cables andtransformers. Generally categorizing future issues from the viewpoint of wire development include; 1)
reliability enhancement (relating to lower cost by improvements in yield and replication); 2) performanceenhancement (high performance attained by in-field characteristics and scribing technology in order toensure the competitiveness of equipment); and 3) fundamental issues (improvement in configuration andcharacteristic anisotropy, fundamental issues related to Y-based superconducting wires such as
superconductor/superconductor joints). In particular, parallel research is necessary to prioritize items 1) and2). The author expects a rapid expansion of potential applications by addressing the issues of item 3)
without delay.
This report partially comprises the research outcomes of projects that have been commissioned by the
Ministry of Economy, Trade and Industry, New Energy and Industrial Technology Development
Organization, and Japan Agency for Medical Research and Development.

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Higher Ic(B) in Long C.C. @ ISTEC
94m long C.C. with Thick EuBCO + BHO film (3.6 μm)
Ic (A/cm-w)

500
400

77 K & 0.3 T

300

STD=2.9%

200
100

77K & 3T

V-tap Distance : 48cm

00 10 20 30 40 50 60 70 80 90 100

Position on Tape (m)Estimation from the minimum Ic
Ic min. > 500 A/cm-w (65K, 3 T)

1

Control of Shielding Current for
DC Coils @ ISTEC & Kyushu Univ.
Effect of Filamentation on
Magnetic RelaxationＴ

2

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Isotropic Coated Conductors( Mechanical & Electromagnetic Properties )Control ofElectromagnetic
Properties

Control of
Mechanical Properties

Stabilizer
Buffer&Super
Hastelloy

Ｔ～120μmLow Aspect Ratio C.C.
Ic

120～200μm• Higher Ic Uniformity＋• Precise Cutting &Scribing Techniques＋• Protection

Angle of B

•Precise Control of APC
based on Xʼtal Growth↓
・Isotropic Behavior at
Temp. & B

3

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Feature Article: Reporting on the 2015 Forum on Superconductivity
Technology Trends-Current Status of Superconductor-based Equipment Development
Undertaken by Toshiba
Kenji Tasaki, Group Leader
Superconductor/Accelerator Technology Development Group,
Electrical Instrumentation System Division,
Power and Industrial Systems R&D Center,Toshiba Corporation
Amid the improving characteristics of high temperature superconducting wires, Toshiba has advanced thedevelopment of conduction-cooled high temperature superconducting equipment from its initialdevelopmental stage. An inherent disadvantage of current conduction-cooling systems is their difficulty with
operating the refrigerator continuously after power cuts and other incidents cause it to stop. There are
however many advantages, which include system compactness, their ease of installation in developing
countries and in remote areas where liquid coolants would be otherwise difficult to supply, as well as simple
cooling operations (cooling commences by only switching on the compressor). The author proposes thatthe most important technological development themes to realize conduction cooling systems involve
fabrication technology that does not lead to degradation in the superconductivity characteristics of hightemperature superconducting coils, and also quantitative studies of thermal runaway analysis to predict
coil-current loading limits. Toshiba has focused their efforts towards the development of high temperature
superconducting equipment, with an emphasis placed on developing such technological issues. Since
precise thermal flows have to be secured within the coil in order to realize conduction cooling, it isnecessary to employ an epoxy-impregnated structure that fills the gaps between the turns. To address this,the author and his team have dedicated their investigations towards the development of
epoxy-impregnated high temperature superconducting coils. There have been no issues withbismuth-based coils. However, yttrium-based coils have had significant degradation in critical currents andn-values. This problem has been addressed in Japan and overseas, and led to buoyant research studies in
research institutions. By introducing a method to reduce the delamination stresses in yttrium-based wires i.e.
inserting a mold release between the turns, the author and his research team were able to fabricate coilswith reduced degradation properties. Additionally, quantitative results from thermal runaway analysis havebeen precisely predicted over the wide ranges of temperatures, corroborating both experimental andanalysis data. The design technology necessary for conduction-cooled high temperature superconducting
equipment has therefore been established for both bismuth and yttrium-based coils. Based upon thetechnological outcomes, the development of high temperature superconducting magnets for a ring
accelerator designed for heavy-ion radiotherapy has been carried out under the JST national project, whilst
the development of a high temperature superconducting magnet for a rotating gantry utilized for heavy-ion
radiotherapy and high-temperature superconducting magnet for high-field MRI have been carried out underthe AMED national project. For these three projects, the fabrication of prototype magnet is planned forcompletion during 2015, along with an evaluation of its performance attributes.
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August 2015

Date of Issue: August 17, 2015

Superconductivity Web21
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KSP, Kawasaki, Kanagawa 213-0012 Japan Tel:+81-44-850-1612, Fax:+81-44-850-1613

Feature Article: Reporting on the 2015 Forum on Superconductivity
Technology Trends-Mitsubishi Electric – Challenges in Manufacturing
Superconductor-based Products
Shunji Yamamoto, Executive Advisor
Mitsubishi Electric Corporation
1. Introduction
For a manufacturer, reliability is always of paramount importance for all types of manufactured products thatare brought to market. From an R&D perspective, the particular focus of investigation is always towards
functionality and performance characteristics. From a practical viewpoint, products that meet their designed
functionality/characteristics, and in addition are inherently reliable are as important as the wheels on an
automobile.
Mitsubishi Electric has 10 business units, where many products from different categories exist, apart frompower equipment and superconducting equipment categories, which will be addressed mainly by this article.
The existing array of products comprises space satellites, elevator/escalators, automobile electricalcomponents, factory automation equipment, high power semiconductors, water filtration units andconsumer electronics such as air conditioning and telecommunication equipment etc. A common
denominator shared by these numerous products is their inherent reliability.
2. Power equipment and superconducting equipment
Superconducting equipment is advancing in the power equipment arena in particular, i.e. transformers,
rotors, breakers, nuclear plants and transmission systems etc. Such equipment requires high levels of
reliability, which has been investigated by the design manufacturing division. This is the reason why thepower equipment manufacturing division is advancing the development of superconducting equipment,
including mutual investigations involving electromagnetic field analysis and magnetic applications.
3. Technology group/engineers to support the manufacturing
A number of technologies to realize the functionality/performance attributes of superconducting equipment
include wire winding, structure, insulation, vacuum, electromagnetic analysis, thermal analysis, stressanalysis etc. Cryostat technology can serve in the background of realizing performance and functionality.
At the start of superconducting magnet development, there was no technology adequate to store helium,
which has a small molecular weight, and this led to slow leaks. Nowadays, this type of incident does notoccur. This demonstrates that product reliability has definitely been realized in the natural course of daily life
during the development dedicated over many years.
As manufacturers, our responsibility is dedicated in promoting fundamental technological skills to ensure
greater reliability and also nurture in-house welding engineers to align welding beads, for example forvacuum resistance welding.

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Date of Issue: August 17, 2015

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4. Practical realization and mass production of superconducting magnets
Dependent on product category types, markets exist where large volumes of superconducting magnets
could be employed i.e. MRI and NMR applications. Currently, there are around 40,000 MRI clinical units
worldwide and the majority employs superconducting magnets as part of their functional operations.
Superconductors utilize direct current simply and with greater reliability. The higher magnetic fields permit
clearer clinical images. The attributes of superconductors can further expand the performance
characteristics of imaging diagnosis.
5. Addressing exceptional superconductor issues
Generally, one of the reasons why superconducting equipment is not easy to use is because of
superconducting fracture events i.e. an occurrence of quench.
It is thus necessary to take measures to prevent quenching and thereby promote their practical realization.
Technologically, the development of wire winding technology that prevents quenching is required.
Alternatively, quenching could be viewed as not a malfunction and an alternative processes maybe required
to ascertain performance, in a similar fashion to quench training.
Mitsubishi Electric continuously aims to improve reliability and challenges the technological skills necessary
to address an array of fields including superconductivity.

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August 2015

Date of Issue: August 17, 2015

Superconductivity Web21
Published by International Superconductivity Technology Center
KSP, Kawasaki, Kanagawa 213-0012 Japan Tel:+81-44-850-1612, Fax:+81-44-850-1613

Feature Article: Reporting on the 2015 Forum on Superconductivity
Technology Trends-High Temperature Superconducting Technology Development at
Furukawa Electric
Shinichi Mukoyama, Director
Telecommunications & Energy Laboratories
R&D Laboratories
Furukawa Electric Co., Ltd.
1.1 The development of superconducting cables
A 275 kV high temperature superconducting cable (HTS
cable) can achieve high-capacity transmissions, which areequivalent to compressed gas-insulated transmission lines
and overhead transmission lines at 1.5 GW, corresponding toa power plant unit. Furukawa Electric has developed 275 kV
3 kA HTS cables, concluding long-term current trials for
30m-long cables in Shenyang City, China. For the practicalrealization of 275 kV superconducting cables and as part ofdemonstration studies of safety and reliability, Tokyo Electric,
Sumitomo Electric, Fujikura, and Mayekawa MFG havecurrently investigated the behavior of ground-fault and shortcircuit incidents as well as security measures necessary to
prevent such incidents. In addition to AC superconducting
cable
development,
thedevelopmentofDC
superconducting cables has been also undertaken taking into
account the potential industrial applications that include trains
and data centers.

Fig.1. 275 kV HTS cable

1.2 The development of superconducting magnetic bearings for the next-generation flywheels
The development of magnetic bearings employing repulsion forces due the Meissner effect has beenachieved by combining bulk superconductors and superconducting coils. Such magnetic bearings havebeen successfully employed to levitate a 4-ton CFRP rotor. Demonstration trials involving a 300 kW
flywheel assembled using these magnetic bearings is underway and engages collaborations between
Railway Technical Research Institute, KUBOTEK, MIRAPRO and Yamanashi Prefecture Government.
1.3 The development of a superconducting magnet for 10 MW-class wind power generator
Future wind power generators are predicted to have larger power outputs, and for offshore wind turbines inparticular, 10 MW-class large-scale wind power generators are anticipated. The combination of asuperconductor and an iron core can realize a direct drive power generator that is compact and easy tomaintain, and therefore suitable for offshore wind turbines. Fundamental studies investigating the design of
a superconducting generator have been undertaken by collaborative undertakings involving AIST and

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August 2015

Date of Issue: August 17, 2015

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Mayekawa MFG. A single-pole racetrack coil has been fabricated and successfully tested at cryocoolingcurrent trials.

Fig.2. Superconducting coil for flywheel

Fig.3. Race-track coil for 10 MW wind power
generator

2. Furukawa’s development of superconducting wires
REBCO coated conductors employed in such high-temperature superconducting equipment are
manufactured by SuperPower, a subsidiary of Furukawa Electric. REBCO coated conductor characteristics
include:1. high in-field characteristics
2. product quality, homogeneity
3. high mechanical characteristics (tensile, delamination)
The introduction of artificial pinning in particular has remarkably enhanced the critical current at low
temperatures and at high magnetic fields, and therefore has proved suitable as wires for magnet
applications. At present, artificial pining using ZrO2 doping up to 15 % has been successful in realizing
enhanced magnetic characteristics and stable performance. Also, the utilization of a Hastelloy substrate
and thermal process optimization has produced REBCO coated conductors with strong tensile anddelamination properties.

Fig.4. Cross-section of a pin within a superconductor anda graph showing Ic improvement

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August 2015

Date of Issue: August 17, 2015

Superconductivity Web21
Published by International Superconductivity Technology Center
KSP, Kawasaki, Kanagawa 213-0012 Japan Tel:+81-44-850-1612, Fax:+81-44-850-1613

This research has been partially undertaken under the following projects:
275 kV superconducting cable: NEDO commissioned project “Development of yttrium-based
superconducting power equipment technology”(2008-2012)
Security/reliability verification: NEDO promotion project “Demonstration studies for security/reliability ofnext-generation transmission system”(2014-2016)
Next-generation flywheel: NEDO promotion project “Development of reliable/low-cost large-scale power
storage system technology”(2011-2015)
Superconducting magnet utilized for 10 MW-class ultra wind power generator: NEDO commissioned
project “Research studies for 10 MW-class ultra wind turbine”(2013-2014)

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