*43 .UNCLASSIFIEDmE ~ ~ UNLIMITED%. i

RESEARCH AND DEVELOPMENT BRANCHDEPARTMENT OF NAIOA DEEC CA AA

by- I.

MacPherson ETDirectorate of SenfcPoicy SEP 2 3 1988

DrUIN ST7cMN A CRAD-REPORTDDitrbuio Uliitd NO. 1/88

Ganada 11 M1A R 1988 OTTAWVA

8 8 9 22 023 UNLIMITED

UNCLASSIFIED QRESEARCH AND DEVELOPMENT BRANCH

DEPARTMENT OF NATIONAL DEFENCE

CANADA

Directorate of Scientific Policy

SUPERCONDUCTIVITY: RECENT DEVELOPMENTS

AND DEFENCE APPLICATIONS (U)

By

R.W. MacPherson DT

SEP 2 3 1988CRAD REPORT 1/88

This paper represents the considered opinionof the author and does not necessarilyrepresent the official views of CRAD.

APPROVED:

Chief, Research and Development 11 Mar 88OTTAWA

iDI.f2UTON STATEMENT A

UNCLASS IFIED frloz p'bH releaselIMrt. h=

UNCLASSIFIED

ABSTRACT

(U) The recent advances in superconductivity have ledto much speculation about the possible applications of thenew technology to all walks of life. In an attempt todetermine what defence applications have realisticexpectations of coming to fruition, a number of opinionssolicited from defence scientists is summarized andreviewed along with information obtained from selectedjournal and magazine articles.

(NC)L'enthousiasme susit6 par les r~centesd~couvertes r6alises dans la domaine dessupraconducteurs a fait l'objet de beaucoup de speculationconcernant les applications possible A toutes sortesd'activit~s de la vie courante. Afin de determinerlaquelles des applications pour la d~fense pr4sentent desprobabilit6s plus que raisonnable d'4tre r~alis~es, lepresent document critique et r~sume sommairement lesopinions de certains scientifiques de la d~fense et aussile contenu de articles sp6cifiques tir6 de journaux et derevues.

e~ft

iii

UNLAS FID//

TABLE OF CONTENTS

ABSTRACT /RtSUM iii

TABLE OF CONTENTS v

INTRODUCTION 1

The 'recent breakthrough' 1The potential impact on defence capabilities

1

BACKGROUND 2

Original discovery 2Current applications 2Limitations of Current Superconductors 3

RECENT DEVELOPMENTS 4

New class of superconducting materials 4Properties 4Limitations of new materials

-- Unresolved problems 6Canadian activities in HTSC 8International HTSC activities 9

APPLICATIONS OF THE NEW MATERIALS 12

IMPACT ON FUTURE CAPABILITIES 16

General 16Commercial 16Defence 17

POSSIBLE INITIATIVES FOR CRAD 20

Close monitoring 20Support of Canadian consortia 20In-house projects 21

CONCLUSION 22

ACKNOWLEDGEMENTS 23

BIBLIOGRAPHY 24

TAbLES

TABLE 1 - APPLICATIONS OF SUPERCONDUCTIVITY 13

TABLE 2 - POSSIBLE TIME OF IMPLEMENTATION FORVARIiTS STTPERCONT'1 CT!'*Y DEVICES 15

v

SUPERCONDUCTIVITY: RECENT DEVELOPMENTSAND DEFENCE APPLICATIONS

Introduction

The 'recent breakthrough'

1. The recent discovery of a new class ofsuperconducting materials has excited members of thescientific community with the possibility of discoveringwhole new mechanisms for producing the superconductingstate and has aroused the technological community with theprospect of realizing many applications once thoughtimpracticable. The heightened interest is due to thesignificantly higher temperatures at whichsuperconductivity is achieved. The temperatures are highenough that cooling can be obtained with relativelyinexpensive and easily produced, liquid nitrogen insteadof the expensive and difficult to produce, liquid heliumrequired for 'conventional' superconductors. Forapplications in space, active cooling may not even benecessary to reach the temperatures required by these newmaterials.

2. This paper is based on a number of ideas submitted byDRE and CRAD/HQ scientists who responded to a request fromDGRD Pol to identify potential applications of the newsuperconductors to defence. Additional information camefrom a selection of magazine and journal articles. Insuch a rapidly moving field as this it is not possible toclaim currency; rather this paper represents a snapshot ofsome of the information published by the end of 1987.

The potential impact on defence capabilities

3. The discovery of high temperature superconductivitycould have an enormous impact on defence capabilities.Representatives from DARPA/ONR have said that it could be"overwhelming", comparable to the impact that theintroduction of transistors had in the era of vacuum

-2-

tubes. In all walks of life, many applications that wereonce abandoned as laboratory curiosities may now befeasible and several others, which had been developed andfielded using liquid helium, show promise of being muchcheaper and easier to obtain, thus opening their use on amuch broader scale. Many of the commercial or civilianapplications will have defence counterparts. Large andsmall scale applications such as computers, electronicdevices, magnets, motors, and sensors are examples.Others products and devices of particular interest to thedefence community include: batteries, bearings,electromagnetic guns and launchers, energy storage, freeelectron lasers, controlled thermonuclear fusion,generators, gyrotrons, magnetic shielding, propulsionsystems, traveling wave tubes, and switches and energystorage devices for directed energy weapons, high poweredlasers and nuclear simulations. Small scale applicationsof interest include optical, IR and microwave detectors,SQUID magnetometers, waveguides and antenna arrays. Theprojected performance capabilities of some applicationsappear almost unbelievable when viewed relative to today'sstandards. For example, a physicist in the U.S. NationalSecurity Agency has suggested the possibility of buildinga superconducting computer with the power of a Cray supercomputer in a package as small as one cubic foot.

Original discovery

4. Originally discovered over 75 years ago in mercury,the phenomenon of superconductivity manifest3 itself bythe complete disappearance of electrical resistance andthe exclusion of magnetic fields from a number ofmaterials when they are cooled below a critical transitiontemperature symbolically represented as Tc. Since 1911when Onnes discovered the phenomenon, the continuingsearch for materials with progressively higher transitiontemperatures has resulted in a steady, linear increase inachievable Tc. By the end of 1986 the maximum obtainedwas 23.3 K.

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Current applications

5. Applications of superconductivity using the oldermaterials have included the creation of high magneticfi~lds for high energy physics, fusion research andnuclear magnetic resonance tomography; quantuminterferometers used in detectors for research intobiomagnetism and gravitational waves; and analogueelectronics devices such as microwave detectors, signalprocessors and voltage references. The requirement forcooling with liquid helium has prevented the developmentof any fielded defence applications although DREP hasexplored the idea of using SQUIDs for magnetic anomalydetection in anti-submarine warfare. The main point tonote is that, with the exception of nuclear magneticimaging scanners used for medical diagnosis, most of theapplications to date have been in laboratory basedresearch tools used in other investigations.

Limitations of Current Superconductors

6. The requirement to cool conventional superconductorswith liquid helium is the main limitation to theirwidespread use. From purely thermodynamicalconsiderations alone it is 25 times cheaper to refrigerateto the 77 K of liquid nitrogen than it is to the 4.2 K ofliquid helium. The inability to withstand high magneticfields and to transport currents at high densities isanother limitation of the early materials. The firstsuperconducting materials discovered were elementalmetals. These materials, called Type I superconductors,lose their superconducting properties in relatively weakmagnetic fields (less than 0.12 tesla) or when carryingsmall electrical currents. The difficulty of making largemagnets which remained superconducting in high magneticfields restricted development of several applications.With the discovery of the so-called Type IIsuperconductors in the 1950s, the critical fields underwhich superconductivity was still possible increased totens of tesla. The type II materials, which offered theprospect of high current capacity and the production ofhigh magnetic fields, have occupied scientists andengineers for the past 20 to 30 years. The principalmaterials used in high magnetic field technology areniobium titanium (NiTi), a ductile alloy that can be

-4-

readily formed into wires, and niobium tin (Ni3Sn), whichcan support very large currents and high magnetic fields,but which has found limited use because of itsbrittleness. Niobium itself has found limited use inradio frequency cavities and niobium nitride (NiN) is usedin electronics.

Recent developments

New class of superconducting materials

7. In 1987 a dramatic change occurred when researchersdiscovered a new class of superconducting materials thatexhibit transition temperatures near 40 K and 90 K. Somematerials were reported with indications of transitiontemperatures at 240 K and up but these results have notyet been verified by independent laboratories. The workthat has followed over the past year has largely beenEdisonian in approach. Many different variations on therecipe have been systematically explored, but no clearunderstanding of why some things work and others do nothas yet emerged. Theoreticians have yet to develop asatisfactory explanation for the high transitiontemperatures or for the existence of superconductivityitself in these new materials. In the meantime there islittle guidance as to what to try next. Until this basicdifficulty is overcome many feel that it is inappropriateto think in terms of developing actual applications atthis point in time. Nevertheless, the first crudeelectronic devices making use of superconductors couldwell appear within a year.

Properties

8. The new superconducting materials are mixed metaloxides that exhibit the mechanical and physical propertiesof ceramics. The large number of the so-called hightemperature superconductors (HTSCs) now known arevariations of two basic types:

a. (Lal.xMx)2CuO4 , where x=0.1 to 0.5 and themetallic elements, M, - calcium (Ca), strontium (Sr),or barium (Ba). Lanthanum (La) is the base rare earthelement. These materials were discovered first andhave transition temperatures in the range 30 K to40 K.

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b. RBa 2Cu 3O 9 _x, where x-2 to 2.4 and the rareearths, R, - yttrium (Y), holmium (Ho), erbium (Er),thulium (Tm), ytterbium (Yb), or lutetium (Lu).These materials exhibit transition temperatures of 90K to 95 K. They are also known as 1-2-3 compounds byvirtue of their composition, whose metallic elementsappear in the ratio of one rare earth (R) and twobarium (Ba) to three copper (Cu) atoms.

9. As ceramics the materials are brittle and, althoughstrong, are susceptible to stress cracking. They lack theductility of the niobium alloys and so cannot be formedinto wires by normal processes. Plasma spraying or othercoating methods on host materials such as aluminum orcopper will have to be developed.

10. The chemical properties of the various 1-2-3compounds are similar. The materials are oxygen deficientoxides with a rough perovskite crystal structure. Theylose oxygen easily when heated to 550 C in vacuum, changefrom the orthorhombic to tetragonal structure and losetheir superconducting properties. The process isreversible when they are reheated at similar temperaturesin an oxygen atmosphere.

11. One of the more peculiar aspects of the materials isthe way in which they reflect light. No matter howsmoothly they are polished their surfaces still appeardull. The reflecting properties of solids reveal muchabout the distribution of their electrons. Metals reflecta lot of light but these materials reflect little andtheir electron distributions, determined by other means,resemble those of insulators rather than conductors.

12. As superconductors, the new materials belong to theType II group although some important differences exist.The transition to the superconducting state, for example,occurs over a range of several degrees instead ofsharply. The superconductivity is anisotropic: thecritical currents depend on the direction in which theypass through the crystals. The critical currents are alsovery low compared to those available in conventional

-6-

superconducting materials. On the other hand, thecritical magnetic fields appear to be very high.Extrapolation of the measurements of the critical fieldsfor the 1-2-3 compounds indicate that at low temperaturethe limits of the upper values lie between 80 and320 tesla. To put this into perspective, the energydensity in a 150 tesla field is about one quarter that ofdynamite. At such levels, however, the forces generatedbetween the field and the current in the wires of themagnet producing it are so large that it would bedifficult to construct a magnet with sufficient strengthto support them.

Limitations of the new materials-- Unresolved problems(Pacing problems/technical barriers)

13. The primary limitation in producing these materialsis the lack of understanding of the reasons for theirsuperconducting properties. Basic research is needed tounderstand why small details of the preparation of the newhigh temperature superconductors lead to dramatic changesin the characteristics of the materials produced. So farelectron pairing as in BCS superconductors has beenconfirmed. Mechanisms proposed as being responsible forthe pairing include:

(a) Phonon electron interaction as in BCS materials(b) Plasmon (collective motion of electrons)(c) Excitons (local polarization of electron orbitals)(d) Magnons (spin fluctuations travelling through the

lattice), and(e) The Resonance Valence Band Theory of Anderson

Chemical and physical stability

14. The lack of basic understanding makes it difficult tomodify the materials to obtain satisfactory physical andchemical properties. The brittleness of the currentmaterials and their poor chemical stability presentsignificant problems. The materials decompose quickly andare difficult to prepare in useful forms. When exposed tothe air they react with water vapour, lose oxygen andrevert to non superconducting materials. Their physical

-7-

and chemical stability under disturbance or transientconditions must be addressed. Stable and structurallysound materials with increased strength and fracturetoughness are needed.

Material fabrication

15. As ceramics they are not easily fabricated intouseful shapes by simple mechanical processes. Processingtechnologies must be developed and techniques found forproducing, reliably and reproducibly, new high temperaturesuperconducting materials that can be fashioned intostructures such as thin films, wires, sheets, coils, etc.,and that have adequate mechanical properties fcr theirintended applicatic.is. Although there is hope thatmanufacturing methods developed for ceramics could beadapted for these new materials, the materials themselvesare not yet suitable for engineering applications.

Low critical current

16. Even in the superconducting state there arelimitations. While these materials remain superconductingin the presence of high magnetic fields, they are, asmentioned above, limited in the current density they cancarry without reverting to normal conductors. The newsuperconductors consist of anisotropic crystalline grains:their electrical conductivity depends on the directionalong the grains in which current flows. To achieve highcurrent densities some alignment process may be necessaryto ensure that individual crystal grains in the bulkmaterials are oriented along the same direction andbrought into closer contact. Currently produced materialsare porous. Their densities are only about 80% of thetheoretical maxima for the known crystal structures andthey must be made more dense. The low current carryingcapacity is the main limitation to high power applications.

Contact resistance

17. Achieving good, low resistivity electrical contactswith the high temperature superconductors is not easy.Being ceramics, the materials are not amenable to welding

-8-

or conventional soldering techniques. Pressed indiv- orsilver metal pads or evaporated noble metal coatings mayprovide solution., but even then finding a way to make acontact that remains reliable over several temperaturecycles between liquid nitrogen and room temperatures is achallenge.

Incompatibility with manufacturing methods formicroelectronics

18. For small scale and low power applications there isan incompatibility between the production processes forsuperconducting materials and microelectronics.Superconductive ceramics must be heated during manufactureto high temperatures ( 900WC) which means that they cannotbe assembled with other materials or components such assemiconductor devices until after they are fired. Thislimits design possibilities.

Need for refrigeration

19. Finally, therp is still the requirement to cool thematerials to liquid nitrogen temperatures. For someapplications to be practicable, superconductors at roomtemperature and above will be necessary. There is hopethat even higher transition temperature materials will bediscovered. Materials with indications of transitiontemperatures above 90 K have been reported, but theirsuperconductivity has only been tested indirectly. Somedirect confirmation is needed.

Canadian activities in HTSC

-0. Canadian activities are widespread. Researchers atBrock University produced the first Canadian paper on thenew materials. McMaster University is concentrating onthe synthesis and physical structure of the materials andon measurements of the energy gap and phonon structure, aswell as strong phonon coupling theory. NRC was one of thefirst laboratories to report on the basic structure. TheTRIUMPH facility UBC, in collaboration with BellLaboratorips, has looked at muon spin rotationmeasurements of the penetration depth of magnetic fieldsinto the superconductors. Basic research is under way atChalk River, University of Toronto, Queen's, RMC Kingston,

-9-

Sherbrooke and Alberta. In addition, considerableinterest is being shown by government agency andindustrial laboratories at Alcan, Atomic Energy of CanadaLimited, Canadian Thin Films, Canedian Wire and Cable,Northern Telecom Electronics, and Ontario and Quebec Hydro.

International HTSC activities

Europe

21. Europe's historical strengths in basic research andindustrial development are being applied to the newsuperconductors. Corporations foster and maintain theEuropean expertise in superconductivity. The Brown BoveriCorporation in West Germany, for example, is amanufacturer of superconducting magnets. Indeed, therecent advances began with Bednorz and Muller's work atthe IBM Laboratory in Zurich.

India

22. India is reported to have established anorganization, led by Prime Minister Gandhi himself, toinvestigate what its involvement in superconductivityresearch should be. Indian Science Council President,C.N.R. Rao has proposed that a national science andengineering foundation examine high temperaturesuperconductivity as one of several frontier technologyareas.

Japan

23. The Japanese have recognized for some time thepotential importance of high temperature superconductors.In the early 1980s the Ministry of Education, Science andCulture established the 'New Superconducting Materials'project whose mandate was due to expire March 1987 but wasrecently extended for another year in light of the recentdiscoveries in HTSCs. In addition, the Ministry hasestablished a new, three year project on HTSCs to start inApril 1988. The Ministry is also planning on anotherproject on applications of superconductivity. TheElectrochemical Laboratory of the Ministry onInternational Trade and Industry has had a long history ofdeveloping suiperconducting magnets for magnetohydrodynamicgenerators and Josephson devices. About 30 scientists at

- 10 -

the Laboratory are now working on the newsuperconductors. In addition there are about 30scientists and engineers at the National Institute forResearch on Inorganic Materials and 50 at the NationalInstitute of Metals also working on the new materials.

24. Japanese industrial efforts on HTSCs are alsoimpressive. In materials development, Fujitsu is workingon superconducting oxide coatings from binders. TheHayashi Chemical has achieved a production rate of 1 tonneper month for ceramic superconductors. Kyocera is alsodeveloping ceramics. Mitsui Mining and Smelting hasachieved a a transition temperature of 99 K in a materialthrough the addition of fluorine. Nippon Chemical ismaking coatings from organic binders fired at 800 C whileToyo Metal has produced a coprecipitation coating onaluminum wire fired at 350 C.

25. Electronics firms are also active. Hitachi hasincorporated a thin film in an optical switch and isproducing SQUIDs for medical use. Matsushita Electric isworking on thin film production by means of magnetronsputtering at 650 C. NEC is investigating Josephsonjunctions for computers and the Sharp Corporation islooking at magnetic sensors for read/write heads.

26. In addition, a number of wire manufacturers areactive: the Sanyo Electric Company has produced a 1 kmlong 29 mil wire with a critical current capacity of 600A/cm at 77 K and Sumitomo Electric has achieved 32,009A/cm 2 at 77 K in an interconnecting film and 1,240 A/cm2at 77 K in a silver enclosed wire. Japan seems to be welladvanced in the field of HTSC. Over 300 papers on the newoxide superconductors appeared in the Japanese Journal ofApplied Physics in the first 9 months of 1987.

Soviet Union

27. The USSR has long-term, aggressive programs in energyconservation, which include superconducting powertransmission and energy storage, the fabrication ofsuperconducting wires and tapes, electronics, particlebeam collider construction, magnetically confined

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magnetohydrodynamics and superconducting generators.Several Soviet laboratory contributions on the new HTSCsare appearing in the literature.

United Kingdom

28. The program of the U.K.'s Science and EngineeringResearch Council (SERC) will probably reach a fundinglevel of $9.7 million U.S. over the first six years. Itwill concentrate on research into high Tc materials. Inaddition, the U.K. Department of Trade and Industry isestablishing a collaborative three year program onsuperconductivity with funding expected to reach $14.5million U.S. This program will likely be moreapplications oriented and will emphasize lower Tcmaterials than the SERC program. Seventeen companies havealready either submitted proposals or expressed aninterest. Electronics, electrical and engineeringapplications will be the main focus.

United States

29. The U.S. administration will soon introduce apackage, entitled "The Superconductivity CompetitivenessAct of 1987", in order to facilitate and speed theprocess by which U.S. leadership in science can betranslated into commerce. The package is expected toconcentrate on relaxing anti-trust provisions, providinggreater patent protection to U.S. patent holders fromforeign competition and to tighten provisions of theFreedom of Information Act. U.S. House representativesDon Ritter and Dave McCurdy are expected to introducelegislation recommending a five year program that wouldreceive $120 million annually for superconductivityrelated activities. The current U.S. expertise in magnetsusing conventional superconducting materials was developedmainly in national laboratories. The large groups workingon the new superconductors in the U.S. are associated withIBM, Allied signal, AT & T Bell Labs, Argonne, Boeing,Corning Glass, Du Pont, Exxon, Ford, General Electric,Hughes, Litton, Lockheed, 3M, Varian Associates andWestinghouse Sandia. Their work tends to be the mostcomprehensive and has produced the more interestingresults with respect to fabricating wires, tapes,Josephson Junctions, thin films and SQUIDs. IBM has thelargest ongoing corporate effort in superconductivity inthe U.S.

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TABLE 1 - APPLICATIONS OF SUPERCONDUCTIVITY

a. Small Scale Applications:

(1) Microelectronics(a) Josephson junctions(b) Battlefield medical diagnostic equipment(c) Guidance systems(d) High density integrated circuits (IC)(e) Inertial navigation systems [(NMR) gyros](f) Millimetre wave gyrotrons(g) Mixers(h) Superconducting delay lines for

communications and surveillanceapplications

(j) Superconducting millimeter wave receiver- satellite communications

(k) Standards for fundamental physicalconstants

(m) Supercomputers

(2) Sensor technology(a) Biomagnetometer(b) Gravity gradiometer(c) Infrared detectors (bolometers)(d) Magnetic Anomaly Detectors (MAD)(e) Microwave detectors(f) Ordnance detection(g) Satellite surveillance(h) Square law detectors(j) Submarine detection(k) Superconducting quantum interference

devices (SQUID)(m) Superconducting radiometer

millimetre/microwave surveillance(n) Target identification and selection

b. Large Scale Applications:

(1) Electromagnetic Propulsion(a) Accelerators(b) Motors and generators - smaller lighter

ship drives

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(c) Projectiles - rail guns(d) Ships - magnetohydrodynamic (MHD) drive

(2) Energy storage devices(a) Magnetic field energy storage(b) Superconducting cells and batteries

(3) High density magnetic field transducers

(4) Magnetic levitation

(5) Magnetic, frictionless be arings

(6) Magnetic separation

(7) Medical apparatus(a) Nuclear magnetic resonance (NMR) imagery(b) Magnetoencephalography (MEG)(c) Magnetomyography(d) Electron spin resonance (ESR) imagery(e) Magnetocardiography

(8) Robotics

(9) Shielding.(a) Electromagnetic interference (EMI)

prevention(b) Electromagnetic compatibility (EMC)

enhancement

(10)Transmission lines(a) Low loss cables (for RF and other

applications)(b) Electrical power transmission

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TABLE 2. - POSSIBLE TIME OF IMPLEMENTATION FORVARIOUS SUPERCONDUCTING DEVICES

K.Taschikawa S. Tanaka N. MakinoAplication Tokai Univ. of Tkyo Mitsiauihic_

Magnetic LevitatedTrain 2000 1995-2000 1995-2000

S.C.-Drive

Ship 2000 1997 1990-1995

Power Line 1995-2000 2000 2000

Power Generator 2000 2000 1995-2000

Power Storage 2000 2000 1990-1995

Josephson Device 2000 1990-1995 1990

IC Package/Substrate 1990 1990-1995 1990-1995

S.C. Semicon. IC 1990 1990-1995 1990

Magnetic Sensors 1990 1995-2000 1990

IR Sensors 1990 1990-1995 1990

MagneticShielding 1990-1995 now 1990-1995

Toys or Kits 1990-1995 1990 1990-1995S.C. Magnet 2000 1995 1990-1995

From: Nippon Keizai Shimbun, 18 May 1987.

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Applications of the new materials

30. Most of the applications that are envisioned for thenew superconducting materials are extensions of devices orsystems already explored or exploited with conventionalsuperconductors operated at liquid helium temperatures.It may be, however, that the most important applicationsthat will eventually evolve will employ new devices notyet contemplated. Applications generally fall into one ofthe two broad classes listed in Table 1. Predictions asto when applications will be available vary but the moreoptimistic positions indicate that within the next 10 to15 years many should be realized. Table 2. presents theviews of three leading Japanese researchers.

Impact on future capabilities

General

31. With the exception of high field magnets for use innuclear magnetic imaging systems, small scale applicationsare expected to come to fruition first. Most qualityelectrical machines are already remarkably efficient at98% to 99%. The use of superconductors to recover the 1%to 2% of the energy lost is generally not cost effective,especially if the capital investment for the new materialsover conventional normal conductors is taken intoconsideration. There is also a considerable investment inconventional machines throughout the world and even ifsuperconducting versions were available at competitiveprices there would be no wholesale movement to replaceeverything. Conversion to superconducting systems wouldonly be undertaken gradually by means of maintenancereplacements. The main advantage for high energyapplications, such as electrical machinery or powertransmission, would be in reducing or eliminating the heatgenerated by losses associated with the conventionaltechnology so that machines could be made smaller. It isestimated, for example, that electric motors, generatorsand transformers could be made about half the size andweight of current devices through the use ofsuperconducting materials.

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Commercial

32. High field magnets for imaging systems and researchpurposes are the main commercial uses of superconductingmaterials. Electronic systems using superconductors areperhaps the most promising applications for the newtechnology. Computer applications will have the greatestimpact but will require more time to develop because oftheir complexity. Sensors and instrument applicationswill probably be commercialized within a few years. Oneelectronics application, using conventionalsuperconductors with liquid helium, has already found itsway into a high speed oscilloscope . Use of HTSCs shouldreduce the cost considerably. Another application is incompact quantum interference devices (SQUIDs) forsensitive magnetic field measurements. Magnetometers haveimportant uses in prospecting. Devices for measurement offundamental physical constants and standards for voltagereferences are also important applications that couldprobably be realized much less expensively and made morewidely available without loss of accuracy. Enhancedmagnetic separation processes for metal extraction mayalso be possible. Finally, magnetic shielding is one ofthe simplest applications that could be exploited early.

Defence

33. Developing more sensitive magnetometers using SQUIDtechnology at liquid nitrogen temperature appears to beone of the first applications of the new superconductingmaterials for defence. One might expect to seedemonstrations of new magnetometers within one or twoyears followed in five years or so by development modelsof MAD equipment that use the new materials and arecompact enough for helicopter borne submarine detectionroles.

34. Superconducting bolometers offer the prospect ofsignificantly enhanced infrared detectors with sensitivityin largely inaccessible wavelength ranges. This shouldresult in much improved FLIRs and space based IRsurveillance capabilities.

35. Millimetre wave devices for satellite communications,radar and surveillance applications, will benefit fromsuperconducting millimetre wave gyrotrons, mixers, anddelay lines.

- 17 -

36. Extremely accurate navigation systems, capable ofextended periods of operation without external radio aids,will be needed for such systems as the nuclearsubmarines. Inertial navigation systems based on nuclearmagnetic resonance gyroscopes using SQUIDs as detectorscould provide the required sensitivity for rotationmeasurement and offer an attractive basis for a strapdownsystem of the future. NASA and DoD have supported work onsuperconducting gyroscopes for many years. The recentadvances in superconductivity show excellent promise thatit will be practical and cost-effective to develop highlyreliable, accurate and long lasting gyroscopes forinertial sensor packages. In addition, the possibility ofbuilding ultra-stable clocks for space or communicationsoffers improvements in such areas as electronic warfare,electronic support measures, and electronic countermeasures.

37. If the limitations in critical current and theincompatibilities with silicon manufacturing technologycan be overcome, higher density integrated circuits (IC)should become more feasible. One of the restrictions nowis due to the heat generated in high density circuits.Superconducting circuits would not dissipate energy asheat. Supercomputers that could be held in the hand andhave the power and speed of Cray machines seem possibleand offer obvious defence capabilities in signal and imageprocessing.

38. One of the most promising application areas is thatrelated to 'medical diagnostics'. Advances insuperconductivity will lead to refinements in NMR and MEGtechnology providing miniaturized, multi-channelinstrumentation which will permit non-invasive monitoringof a wide range of body functions, dynamically and in realtime. Measurement of metabolism in tissues and organs ofthe body could become possible, directly and automaticallyso that brain, heart and muscle functions could bemonitored non-invasively in the field. Such enhanceddevelopment of magnetoencephalographic (MEG) techniquesfor non-invasive monitoring could enable assessment ofhuman capability in operational environments. In the longterm, advances in MEG technology may well eventually leadto 'thought control' of systems.

- 18 -

39. The non-invasive nature of NMR imaging systems couldhave direct benefits to the CF Medical Services. The newsuperconductors may make it possible to developbattlefield medical diagnostic equipment that is compactand portable. Not only could diagnoses and monitoring ofpatients be done non-invasively, but also remotely (noskin contact or body contact required). Casualties inadverse environments (NBC, cold weather, etc.) could bediagnosed or monitored without the removal of theirprotective garments. Magnetocardiography,magnetomyography and magnetoencephalography (to name afew) could even be performed as far forward as the firsttriage. There is, however, the problem of placing personswith wounds, containing metal shrapnel, in the intensemagnetic fields of such systems. The magnetic fieldscould exert considerable force on any metal fragmentswithin the body.

40. In the longer term, high energy, large scaleapplications should be possible, especially if roomtemperature superconductors are discovered.Electromagnetic propulsion using superconductors couldprovide enhanced performance for particle beamaccelerators, electromagnetic launchers (rail guns), andeven possibly magnetohydrodynamic (MHD) drives for shipsand submarines. Practical, compact and powerful motorsand generators for smaller, lighter ship drives are a morelikely prospect and would probably appear first. Magneticlevitation and frictionless magnetic bearings could resultin more efficient and quieter machinery. NASA is lookingat magnetic braking of hypersonic aircraft and spacecraftduring reentry in order to reduce aerodynamic heating sothat ablative shield material may be reduced or eliminatedfrom some of the vehicle surfaces.

41. Energy storage devices using superconducting magnetsfor load leveling and superconducting batteries offerprospects for new electrical energy sources. Similarly,superconducting transmission lines would make developmentof low loss cables for RF and electrical powertransmission a possibility.

42. Superconducting materials provide the bestelectromagnetic shielding characteristics. Applicationsresulting from this property will be

- 19 -

particularly important to the defence field in areas suchas prevention of electromagnetic interference (EMI),hardening against electromagnetic pulse (EMP) andtransient radiation electronic effects (TREE), andenhancement of electromagnetic compatibility (EMC) forcommunications, surveillance and signal processing systemsas well as mine hunting and possibly shielding of rail guncrews.

43. The use of superconducting materials for elements ofshort, high frequency (HF) antennas and microwave cavitiesshould greatly improve efficiency. A recent applicationusing superconducting microwave cavities for particleaccelerators indicates that duty cycles could be raisedfrom 1:1000 or 1:10,000 to almost 1:1 and that severalmillion volts per metre accelerating voltages arepossible. With higher temperature superconductors suchdevices would be considerably simpler to make andoperate. Particle beam weapon and free electron laserdevelopment may benefit from this advance.

Possible initiatives for CRAD

44. It is very early to determine which applications willultimately come to fruition and which will be blocked byserious problems. Much of what is known is not yetpublished due to the time lag between discovery andpublication. There are also indications that details,especially those of fabrication techniques, may be beingheld back to protect commercial interests.

45. It will be important to stay in the game on a worldwide basis in order to exploit developments in a timelyfashion. We should begin our familiarization with thisfield now if we plan to exploit it fully when HTSCmaterials become available.

Close monitoring

46. As a minimum activity, staff should attendconferences and visit laboratories as much as possible inorder to keep abreast of progress in this rapidlydeveloping field.

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Support of Canadian consortia

47. Experimental work should capitalize on existingexpertise on a consortium basis with industry,universities, OGDs and agencies, etc. Actively supportingresearch work in the HTSC materials in bulk and thin filmform, and in Josephson junctions and SQUIDs constructedfrom such materials would reap the greatest short termbenefits. Efforts should be supported at more than a fewuniversities and industries. Developing fabricationtechniques and establishing good centres forcharacterizing the materials are two important areas topursue. It would also be important to explore thin filmdevices such as SQUIDs and IR detectors (bolometers), andinvestigate heavy current applications.

Universities

48. A number of universities have formed loosecooperative groups to explore the new technology. Withsome funding from NSERC and contributions from variousindustries, the basis for a core of expertise is beingestablished in Canada, but at a much smaller scale thanelsewhere in the world. Nevertheless Canadians can makeand have made significant contributions: namely, NRC'smapping of the crystal structure of the new materials andMcMAster University's growing reputation as a centre ofexcellence in superconducting materials science. To theextent that CRAD could identify specific aspects of thetechnology that appear to have defence application, somecontractual support to these consortia might beappropriate. As results become more promising, DSs mightbe seconded to such consortia as a form of sabbaticalleave or alternatively arrangements could be made for anexchange of scientists if suitable programs could beworked out.

Selected Canadian companies

49. Canadian companies that possess expertise insuperconductivity or have the potential to acquire itshould be identified and supported early in developingdefence applications of superconductivity. In many casesthis would probably be accomplished by supporting variousindustrial university consortia.

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In-house projects

50. In order to develop expertise and be able to positionourselves to address defence applications of the newsuperconducting materials, a number of in-house activitieswould be appropriate. For example, ideas received fromthe Research Establishments, CRAD/HQ and RMC suggestedthat it would be worthwhile to:

a. Demonstrate applications in MAD for helicopters.

b. Determine the feasibility of developing:

(1) a superconducting gyroscope, and

(2) a superconducting gravity gradiometer.

c. Improve DRE facilities and/or contribute toupgrading national characterization facilities inorder that devices and applications using newsuperconductors can be evaluated for potentialdefence purposes. Devices for which facilitieswould be of particular interest include:

(1) IR Detectors

(2) microwave devices, and

(3) magnetic detectors.

d. Investigate the possibility of using NMR imagingsystems for diagnostic purposes on casualtiesworking in a CW/BW environment. The newsuperconductors may make field portable systemsfeasible.

e. Examine, in the long term, the potential benefitsof using superconductors for electrical powertransmission in ship and submarine propulsionsystems.

51. One possible approach to increasing involvement inthe area would be to allow some reasonable percentage ofthe R&D effort to be put toward

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superconductor related activities. NASA, for example, hasallowed its centres to reprogram up to 15% of theirbudgets for research into HTSC materials for fiscal year1988.

52. High temperature superconductivity is a major newadvance in technology that has great potential in a widerange of areas. However, the prospects for success indeveloping the various applications are still unclear.Much has been discovered recently and it is expected thatadvances will be made rapidly over the next few years.Resolution of the critical current and stability problemsmight delay significant commercial use of the technologyfor some time. On the other hand, defence applicationsthat rely on SQUIDs and superconducting magnets shouldappear relatively soon.

Acknowledgements

53. The contributions of the scientific staff of DGRD Opsand the DREs are gratefully acknowledged. In particular,the ideas provided by J.J. Grodski and Bob Angus anddiscussions held with Dr. S.M. Khanna were most useful.Mr. Ellington's editorial suggestions were muchappreciated.

BIBLIOGRAPHY

Baird, D.C., Wright, L.E. and Batalla, E., RMC,Briefing to RDEC, CRAD Conference Room, 1 Dec 1987.

Beardsley, Timothy M., "Getting Warmer", Science andthe Citizen, Scientific American, Oct 1987,pp 32 - 34.

Buttner, H. and Blumen, A., "Possible explanation forthe superconducting 240-K phase in the Y-Ba-Cu-Osystem", Nature, Vol. 329, 22 Oct 1987, pp. 700 - 701.

Chu, F.Y., Ontario Hydro Research Division. "RecentDevelopments in High Tc Superconducting MaterialResearch and Applications", NRC Division ofElectrical Engineering, SCIENCE ASSOCIATION,18 Nov 1987.

Clarke, John, "SQUIDs, brains and gravity waves",Physics Today, March 1986, pp 36 - 44.

Felici, R., Penfold, J., Ward, R.C., Olsi, E., andMatacotta, C., Determination of the magnetic

penetration depth of the high-Tc superconductorYBa2 Cu30 7 by polarized neutron reflection", Nature,Vol. 329, Oct 1987, pp. 523 - 525.

Forgen, Ted, "Superconducting ceramics: Findingcharacteristic lengths", Nature, Vol. 329, 8 Oct1987, pp. 483 - 485.

Hayakawa, Hisao, "Josephson computer technology",Physics Today, March 1986, pp 46 - 52.

Hughes, David, "Pentagon Boosts Research Spending ToDevelop Practical Superconductors", Aviation Week &Space Technology, 16 Nov 87, pp 57 - 59.

Larbalestier, David; Fisk, Gene; Montgomery, Bruce andHawksworth, David, "High-Field Superconductivity",Physics Today, March 1986, pp 24 - 33.

Lemonick, Michael D. Science, Time Magazine,11 May 1987, pp 56 - 63

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Manthiram, A. and Goodenough, J.B., "Synthesis of thehigh-T c superconductor YBa2Cu3 07_ in small particlesize", Nature, Vol. 329, 2 Oct 1987, pp. 701 - 703.

Maple, M. Brian, "Novel types of superconductivity inf-electron systems", Physics Today, March 1986, pp 72- 80.

McKinnon, Ross, NRC. "High Tc Superconductivity inPerovskites", Ottawa-Carleton Institute Seminar,University of Ottawa, 1 Oct 1987.

Muller, K. Alex and Bednorz, J. Georg, "The Discoveryof a Class of High-Temperature Superconductors",S , vol 237, 4 Sep 1987, pp 1133-1139.

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Robinson, Arthur L., "More Superconductivity QuestionsThan Answers", Research News, Science, Vol 237, 17July 1987, pp 248 - 250.

Science and Technology, "Not-so-superconductors",The Economist, 13 June 1987, pp 93 - 99.

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(U) The recent advances in superconductivity have led to much speculation aboutthe possible applications of the new technology to all walks of life. In anattempt to determine what defence applications have realistic expectations ofcoming to fruition, a number of opinions solicited from defence scientists issummarized and reviewed along with information obtained from selected journal andmigazine articles.

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