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OCR for page 1
Report of the
Research Bnefing Panel on
High-Temperature Superconductivity
OCR for page 2
Research Beefing Panel on
High-Temperature Superconductivity
John K. Hulm (Chairman), Director,
Corporate Research and R&D Planning,
Westinghouse R&D Center, Pittsburgh,
Pa.
Neil W. Ashcroft, Professor of Physics,
Cornell University
Roger W. Boom, Professor and Director,
Applied Superconductivity Center,
Nuclear Engineering and Metallurgical
Engineering, College of Engineering,
University of Wisconsin, Madison
H. Kent Bowen, Ford Professor of
Engineering, Massachusetts Institute of
Technology
Robert l. Cava, Technical Staff, AT&T Bell
Laboratories, Murray Hill, N.~.
Paul C.W. Chu, Temple Chair in Science,
University of Houston, Tex.
John Clarke, Professor of Physics,
University of California, Berkeley, and
Principal investigator, Lawrence Berkeley
Laboratory
Marvin L. Cohen, Professor of Physics,
University of California, Berkeley
2
lames S. Edmonds, Senior Project Manager,
EPRT, Palo Alto
Douglas K. Finnemore, Associate Director,
Science and Technology Division, Ames
Laboratory, Department of Energy
Eric B. Forsyth, Chairman, Accelerator
Development Department, Brookhaven
National Laboratory
Theodore H. Geballe, Professor of Applied
Physics, Stanford University
David C. Larbalestier, Associate Director,
Applied Superconductivity Center,
Department of Metallurgical Engineering,
University of Wisconsin, Madison
Charles Laverick, Private Consultant,
Patchogue, N.Y.
Alexis P. Malozemoff, Division Coorclinator
for High-Temperature Superconductivity,
T.~.Watson Research Center, IBM
Corporation
lames H. Parker, Private Consultant, Penn
Hills, Pa.
David Pines, Professor, Loomis Laboratory
of Physics, University of Illinois, Urbana
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HIGlI- TEMPE - TURE S UPER COND UCTIVI~
Carl H. Rosner, President, Intermagnetics
General Corporation, GuilclerIand, N.Y.
John Rowell, Assistant Vice President, Solid
State Science and Technology Research
Laboratory, Bell Communications
Research, Red Bank, N.~.
Arthur Sleight, Research Leader, Central
Research and Development Department,
Experimental Station, A. duPont de
Nemours & Company
lames L. Smith, Senior Scientific Advisor,
Center for Materials Science, Los Alamos
National Laboratory
Masaki Suenaga, Senior Metallurgist,
Department of Applied Sciences,
Brookhaven National Laboratory
Maury Tigner, Director, SSC Central Design
Group, Universities Research Association
3
Michael Tinkham, Rumford Professor of
Physics and Gordon McKay Professor of
Applied Physics, Harvard University
John Williams, Head, Magnet Technology
Division, National Magnet Laboratory,
Massachusetts Institute of Technology
Committee on Science, Engineering, and Public
Policy Staff
AlIan R. Hoffman, Executive Director
John R. B. Clement, StaffOff'cer
Barbara A. CandIand, Administrative
Coordinator
Cathy D. Dyson, Senior Secretary
Nisha Govindani, Senior Secretary
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Report of the
Research Bnefing Panel on
[ligh-Temperature Superconductivity
EXECUTIVE SUMMARY
The recent discovery of superconductivity
at temperatures up to 95 K is one of the more
important scientific events of the past dec-
ade. The sheer surprise of this discovery, as
well as its potential scientific and commercial
importance, largely underlie the degree of
excitement in the field. Because our previous
understanding of superconductivity has
been so funciamentally challenged, a cloor
has been opened to the possibility of super-
conductivity at temperatures at or above
room temperature. Such a development
would represent a truly significant break-
through, with implications for widespread
application in modern society.
While the base of experimental knowledge
on the new superconductors is growing rap-
idly, there is as yet no generally accepted the-
oretical explanation of their behavior. Appli-
cations presently being considered are
largely extrapolations of technology already
under investigation for Tower-temperature
superconductors. To create a larger scope of
applications, inventions that use the new
materials will be required. The fabrication
and processing challenges presented by the
new materials suggest that the period of pre
5
commercial exploration for other applica-
tions will probably extend for a decade or
more.
Near-term prospects for applications of
high-temperature superconducting materi-
als include magnetic shielding, the voltage
standard, superconducting quantum inter-
ference devices, infrared sensors, micro-
wave crevices, and analog signal processing.
T onger-term prospects inclucle large-scare
applications such as microwave cavities;
power transmission lines; and supercon-
ducting magnets in generators, energy stor-
age devices, particle accelerators, rotating
machinery, medical imaging systems, levi-
tated vehicles, and magnetic separators. in
electronics, long-term prospects include
computer applications with semiconduct-
ing-superconducting hybrids, Josephson
devices, or novel transistor-like supercon-
ducting devices.
The United States has a good competitive
position in the science of this field, and U.S.
researchers have contributed significantly
to the worldwide expansion of scientific
knowledge of the new materials. Interna-
tional competition is intense. Several other
leading industrialized countries have
mounted substantial scientific and techno
OCR for page 6
logical efforts, especially Japan, a number of ing on synthesis, processing, stability, and
Western Euronean nations ~nr1 the I JEER methods for large-scale production;
. _ ,~ , ~ ~ . ~
The short-term problems and long-term
potential of high-temperature superconduc
tivity may both be easily underestimatecl.
Given this potential and the current limited
understanding of the new superconducting
materials and their properties, it is essential
that government, academic institutions, and
industry take a long-term, multidisciplinary
view. Since science and technology in this
field are strongly intertwined, progress must
occur simultaneously in basic science, man
ufacturing/processing science, and engi
neering applications. It is also important to
maintain an open and cooperative interna
tional posture.
The panel has identified eight major scien
tific and technological objectives for a na
tional program to exploit high-temperature
superconductivity. They are:
I. to improve understanding of the essen
tial properties of current hi~h-temnerature
. .
C~ - r ~
superconducting materials (especially Tc'
HC2' fc, and alternating current losses)
through the acquisition of additional experi-
mental data;
2. to develop an understanding of the ba-
sic mechanisms responsible for supercon-
ductivity in the new materials;
3. to search for additional materials exhib-
iting superconductivity at higher tempera-
tures by the synthesis of new compositions,
structures, and phases;
4. to prepare thin films of controllable and
reproducible quality from present high-tem-
perature superconducting materials anc! to
establish preferred techniques for growing
films suitable for electronic device fabrica-
tion;
5. to develop bulk conductors from cur-
rent high-temperature superconducting ma-
terials, with special emphasis on enhanced
electric current-carrying capacity;
6. to advance the understanding of the
chemistry, chemical engineering, and ce-
ramic properties of the new materials, focus
6
7. to fabricate a range of prototype circuits
and electronic devices based on su-
perconducting microcircuits or hybrid
superconductor/semiconductor circuits, as
suitable thin film technologies become avail-
able; and
8. to fabricate a range of prototype high-
field magnets, alternating and direct current
power devices, rotating machines, transmis-
sion circuits, and energy storage devices, as
suitable bulk conductors are developed.
The panel recommends that the following
actions be taken to carry out the objectives
listed above:
· The U.S. government should proceed
with its plans to provide funding for high-
temperature superconductivity research
and development on the order of $100 mil-
lion for fiscal year 1938. This funding level
represents a good beginning in addressing
the challenges and opportunities offered by
the new materials.
· Sufficient new money must be provided
both to the science and the technology of
high-temperature superconductivity so that
other important and promising areas of re-
search and development are not held back.
· A mechanism should be established to
monitor the potential demand for increased
scientific and technical manpower if the
promise of high-temperature superconduc-
tivity is fully realized, and to make appropri-
ate recommendations on the funding of U. S.
graduate and postgraduate research pro-
grams.
· An interagency mechanism should be
established to help coordinate planning for
superconductivity programs among the var-
ious federal agencies.
· Given the anticipated rate of advance in
high-temperature superconducting science
and technology, the federal government
should review progress in the field after 12
months as a guide to future resource alloca-
tion.
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HIGH-TEMPERATURE S UPERCOND UCTIVITY
· Through its agencies, the U. S. govern-
ment must enhance the probability that U. S.
industry gains a competitive advantage in
this new fielcI. This could be accomplishec!
by the close association of industry with the
Engineering Research or Science and Tech-
nology Center programs of the National Sci-
ence Foundation, by cost-sharing between
government and industry on proof-of-con-
cept projects, and by other joint efforts.
7
· An important mechanism for enhancing
U.S. industry's position is improved tech-
nology transfer from the national laborato-
ries to the private sector. Although a variety
of means are already in place to encourage
such transfer, the pane! is concerned about
the effectiveness of past efforts anc! urges
both government and industry to pursue
linkages more aggressively.
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INTRODUCTION
Perhaps the most remarkable feature of
the discovery of high-temperature super-
conductivity is the fact that it was so unex-
pected. The sheer surprise of this discovery,
as well as its potential scientific and commer-
cial importance, largely underlie the degree
of excitement and fervor of the field. Super-
conductivity in the past has always been a
challenging fundamental and technological
problem, for which understancling and ap-
plication have come slowly. Because our pre-
vious understanding of superconductivity
has been so fundamentally challengeci, there
is hope that the progress that has been
achieved so dramatically in the past IS
months can be continued.
High-temperature superconductivity of-
fers an important opportunity for our na-
tion's scientific and technological commu-
nity. The opportunity merits a substantial
thrust in fundamental research; at the same
time, enough is already known to encourage
commercial development efforts with the
newly discovered materials.
BACKGROUND
Superconductivity was discovered by a
Dutch scientist, Kamerlingh Onnes, in 1911.
He found that the electrical resistance of
frozen mercury (Hg) disappeared suddenly
at 4.2 degrees Kelvin (K) (-269 degrees Cel-
sius tCl), a temperature accessible only
through immersion in liquid helium. In 1913
Onnes also found that weak magnetic fields
(of a few hundred gauss) destroyed the ef-
fect, with the metal reverting to its normally
resistive state. Subsequently, other metals
such as tin (Sn) and lead (Pb) were founc! to
be superconductors at similarly low temper-
atures. People soon began to invent applica-
tions for superconductors for example, to
reduce Tosses in electric power systems.
However, in the 1920s it was found that su-
perconductivity disappeared in these met
als when rather Tow electric currents were
passed through them. As a result, power ap-
plications were abandonecl.*
Significant progress in understanding the
physical basis of superconductivity came in
the 1950s. In the theory of Barcleen, Cooper,
anc! Schrieffer, interaction between elec-
trons and "phonons" (vibrational modes in
the lattice of atoms making up the material)
leads to a pairing of electrons. At Tow tem-
peratures, these so-called Cooper pairs con-
dense into an electrical superfluid, with en-
ergy levels a discrete amount below those of
normal electron states (known as the super-
conducting energy gap). in the same period,
new materials were discovered that dis-
played superconductivity at temperatures as
high as 20 K, almost 5 times higher than the
temperature of superconductivity in mer-
cury.
These scientific discoveries had two im-
portant consequences. First, in a direct ex-
periment to verify the energy gap, Giaever at
the General Electric Research Laboratories
observed electron tunneling between super-
conductors that is, electrons passing from
one superconductor to another through a
thin insulating barrier. The observation of
normal electron tunneling lecl Josephson in
England to speculate that Cooper pairs could
also tunnel through a barrier, a prediction
that was soon verified by Rowell and Ancler-
son at Bell Laboratories. These discoveries
laid the foundation for a whole new super-
conclucting electronics technology.
Second, Kunzler and coworkers at Bell
T aboratories established that a group of su-
perconducting compounds and alloys (the
Type-2 superconductors) could carry ex-
tremely high electric currents (up to a million
amperes per cm2 of conductor cross-section)
and remain superconducting in intense
magnetic fields (up to 30 tesla iT] or 300,000
*Electric utility equipment typically carries thousands
of amperes and has associated magnetic fields of up to
20,000 gauss or 2 tesla.
8
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HIGH- TEMPERATURE S UPER COND UCTIVITY
gauss). These materials, offering the pros-
pect of very high magnetic fielcls and cur-
rent-carrying capacity at a much Tower cost
than before, revived interest in super-
conducting magnets and electric power
components.
In the years between 1960 and 1986, sev-
eral hundred materials were found to be su-
perconducting at sufficiently low tempera-
tures. However, the highest critical tempera-
ture (i.e., the temperature below which a
material becomes superconducting, Tc)
achieved in this period was 23 K, which still
required either liquid helium or liquid hy-
drogen cooling.
The workhorse of the high-field magnet
technology has been niobium-titanium
(NbTi), a ductile alloy that can be made into
wires. A second material of great promise,
niobium-tin (Nb3Sn), can support even
larger electric currents and remain supercon-
ducting in higher magnetic fields, but it has
found much less use because of its brittle na-
ture. Other materials have found more lim-
ited uses for example, pure niobium in ra-
diofrequency cavities and niobium nitride
(NbN) in electronics.
RECENT DISCOVERIES
Recently, new materials have been discov-
ered that have substantially higher TCS. In
January 1986 Bedsore and Muller, working
at the IBM Laboratory in Zurich and search-
ing for superconductivity in previously
unexplored materials, determined that a lan-
thanum-barium-copper ceramic oxide be-
came superconducting at temperatures over
30K.
Spurred on by this unexpected discovery,
laboratories in the United States and else-
where have since found materials with even
higher Ts. The highest stable value to date
that has been independently confirmed, 95
K (-178 C), was first achieved by Chu and
colleagues at the University of Houston
working with Wu and coworkers at the Uni
9
versity of Alabama. At this temperature, liq-
uid nitrogen (which boils at 77 K at atmo-
spheric pressure and is much cheaper than
liquid helium) can be used for cooling.
A large number of the so-called high-tem-
perature superconductors are now known to
exist, all of them variations of two basic types
(the so-called 40 K and the 95 K for I-2-3] ma-
terials). Those with TC greater than 77 K are
based on only one structure, with copper
(Cu) and oxygen (O) a constant feature.
The new materials present an enormous sci-
entific opportunity and open new vistas for
potential applications. Because our under-
standing of superconductivity has been chal-
lenged in so fundamental a fashion, with the
present theoretical understanding of super-
conductivity being insufficient to explain the
properties of the new materials, there is
hope that what has been achieved in such a
short time can be extended. The excitement
surrounding the field has caught the imagi-
nation of policymakers, the media, and the
public at large. Research students are also at-
tracted by this excitement, often being
drawn from other areas of science by the
prospect of careers in the field; but it is im-
portant to note that they are drawn from a
manpower pool that can only be expanded
slowly.
There have been several preliminary re-
ports of superconductivity at still higher
temperatures, but at present there is no con-
sensus as to their validity. It is likely that
room-temperature superconductivity would
make possible a much broader range of ap-
plications. A more immediate concern is
whether the present high-temperature su-
perconductors can be used to improve
present electronic or power applications; on
this question, researchers worldwide are
cautiously optimistic.
*Some of the manpower issues are discussed in Physics
Through the 1990s: An Overview, Washington, D.C.:
National Academy Press, 1986.
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CURRENT KNOWLEDGE OF
THE NEW HIGH-TEMPERATURE
SUPERCONDUCTORS
The new high-temperature superconduc-
tors are mixed metal oxides that display the
mechanical and physical properties of ce-
ramics. A key to the behavior of the new ma-
terials appears to be the presence of planes
containing copper and oxygen atoms chemi-
cally bonded to each other. The special na-
ture of the copper-oxygen chemical bonding
gives rise to materials that conduct electricity
well in some directions, in contrast to the
majority of ceramics, which are electrically
insulating.
The first class of high-TC oxides discoverec!
was based on the chemical alteration of the
insulating ternary compound La2CuO4 by
replacement of a small fraction of the ele-
ment lanthanum (La) with one of the alkaline
earths barium (Ba), strontium (Sr), or cal-
cium (Ca). The substitution led to com-
pounds with critical temperatures of up to 40
K. In these materials, an intimate relation be-
tween superconductivity anc! magnetic or-
der is presently uncler intensive study and
has inspired one of the many classes of theo-
ries that attempt to explain high-tempera-
ture superconductivity.
In a second class of compounds, based on
YBa2Cu3Ox (where Y is yttrium, a rare earth),
the metallic atoms occur in fixec! pro-
portions. These are the so-called 1-2-3
compounds, which are highly sensitive to
oxygen content, changing from semicon-
ducting, at YBa2Cu306.5, to superconducting
near 95 K at YBa2Cu307, without losing their
crystalline integrity. The high sensitivity of
their properties to oxygen content is due to
the apparent ease with which oxygen can
move in and out of the molecular lattice.
The 40 K and 1-2-3 (or 95 K) materials have
similar structures but differ significantly in
other respects. In both compounds, the rare
earth and alkaline earth atoms provide a
structural framework within which the
chains of copper and oxygen atoms may be
hung.
Surprisingly, the substitution of other rare
earths, even magnetic ones, for yttrium in
the 95 K compounds results in very little
change in superconducting properties. Vari-
ous substitutions are under study, both to
understand the present materials and to
achieve higher critical temperatures in new
ones.
STATUS OF THEORETICAE UNDERSTANDING
In the microscopic theory of Bardeen-
Cooper-Schrieffer, the presence of a net at-
tractive interaction between conduction
electrons, which would normally repel each
other because of their like electrical charges,
is essential to the occurrence of supercon-
ductivity. In conventional superconductors
this attraction originates in the dynamic mo-
tion of the crystal lattice, which leads to an
attractive ''electron-phonon-electron" in-
teraction. But the recent appearance of su-
perconductivity in a class of materials quite
different from the conventional supercon-
ductors, and with extremely high transition
temperatures as well, has led physicists to
explore a very wide spectrum of possible
new pairing mechanisms involving, for ex-
ample, spin fluctuations, acoustic plasmons,
and excitonic processes. The physical origin
of the pairing "glue" remains an open and to
some extent crucial question. There is a wide
range of theoretical possibilities, and the ul-
timate explanation may involve a combina-
tion of mechanisms. Indeed, some theorists
have discarded conventional Bardeen-
Cooper-Schrieffer theory and have sug-
gested that there may not even be the tradi-
tional close relationship between energy
gaps and basic superconducting properties.
Given the wealth of puzzling experimental
features in a variety of different materials, it
may take a considerable effort, with a diverse
theoretical program, to unravel fully the se-
crets of these compounds. In the meantime
10
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HIGH- TEMPERATURE S UPERCOND UCTIVITY
the fact that they obviously do exist can form
the basis of immediate commercial exploita-
tion. But the prospect of even more promis-
ing materials has led to a substantial theoreti-
cal effort aimed at eTuciciating the principles
underlying the phenomenon. Typical of the
questions currently under active consider-
ation are the role played by oxygen, the na-
ture and scope of dynamic mechanisms and
the resulting electron pairing, whether this
coupling is weak or strong, and whether the
anisotropic nature of the materials is a truly
important feature. The appearance of super-
conducting coherence lengths ~ or 2 orders
of magnitude smaller than those previously
encountered, the very low carrier concentra-
tions, and the apparent importance of both
copper and oxygen will probably require a
considerable extension of our current undier-
standing of superconductivity. The fact that
the superconducting interaction mechanism
in the new materials is likely to be very differ-
ent from that in low-temperature supercon-
ductors certainly enhances the prospect that
other high-temperature superconducting
materials may be discovered.
PHYSICAL PROPERTIE S IMPORTANT
FOR TECHNOLOGY
The most important physical properties
for applications are the superconducting
critical temperature (Tc), the upper critical
magnetic field (Had' and the maximum cur-
rent-carrying capacity in the superconduct-
ing state (/c) Also important are the mechan-
ical, chemical, and electromagnetic proper-
ties: physical and thermal stability, resis-
tance to radiation, and alternating-current
loss characteristics. Each is discussed more
fully below.
CriticaZ Temperature, Tc
A rule of thumb for general applications is
that materials must be operated at a tempera-
ture of 3/4 Tc or below. At about 3/4 Tc critical
11
fielcis have reached roughly half their low-
temperature limit, and critical current densi-
ties roughly a quarter of their limit. Thus,
to operate at liquicl nitrogen temperature
(77 K), one would like Tc near 100 K, making
the 95 K material just sufficient. To operate at
room temperature (293 K) one requires a ma-
terial with Tc greater than 400 K, well above
the highest demonstrated value. Higher Tc
materials would be superior across the board
for applications, other properties being ac-
ceptable, and materials with TCS above 400 K
would have a truly revolutionary impact on
technology. In this temperature domain one
could consider mass market applications.
Upper CriticaZ Magnetic FieZci, Hc2
YBa2Cu3O7 samples generally exhibit ex-
tremely high upper critical fielcls. Prelimi-
nary measurements indicate that for single
crystals HC2 is anisotropic, that is, dependent
upon field direction relative to the a-, b-, or c-
axes of the orthorhombic lattice. Values
ranging from 30 T (c-axis) to 150 T (a- or b-
axes) are reported at 4.2 K. The mechanical
stresses associated with the confinement of
such high magnetic fields in typical compact
geometries are frequently beyond the yield
or crushing strengths of known materials.
Hence, improving these intrinsic HC2 values
is less important than increasing Tc or Ic val-
ues. In fact, materials with higher TCS should
exhibit higher HC2 values if the performance
of known materials is any guide. However,
developing materials that can practically be
fabricated into magnets and that retain use-
fuT lcs at fields approaching HC2 even at 77 K is
an important challenge.
CriticaZ Current Density, fc
For practical applications, k values in ex-
cess of 103 amperes per square millimeter
(A/mm2), are desirable both in bulk conduc-
tors for power applications and in thin film
superconductors for microelectronics.
OCR for page 14
the new materials. A better understanding
of phase equilibria, solid solutions, and in-
termetallic compounds is needed to find sta-
ble ohmic contacts that do not degrade su-
perconducting behavior.
NEW SUPERCONDUCTING MATERIALS
Finally, we must not neglect the search for
new compounds with intrinsically superior
superconducting properties. Operation at
77 K leaves little margin when running a de-
vice that utilizes a superconductor with a TC
of 95 K. Cryogenic systems that operate be-
low 77 K should be investigated, and the
compatibility of high-temperature super-
conductors with refrigerants other than liq-
uid nitrogen (e.g., liquid neon) should be
tested. Further, and perhaps most impor-
tantly, the events of the past year have
shown that surprises do occur, and it may be
that superconductivity at or above room
temperature may be detectecI at some future
date in compounds not yet stuctied.
CURRENT FIELDS OF APPLICATION
AND THE LIKELY IMPACT OF
THE NEW MATERIALS
Virtually all of the applications currently
envisioned for high-temperature supercon-
ductors are extrapolations of devices already
operated at liquid helium temperatures. The
most important applications, however, may
well involve devices that have yet to be con-
templated, much less invented.
As shown in Table 1, present and potential
applications fall into several distinct classes.
Present applications include high-field mag-
nets, radiofrequency devices, and electron-
ics. Superconductivity brings unique ad-
vantages to high-field applications because
resistive conductors such as copper dissipate
large amounts of energy as heat when carry-
ing large currents. Superconductors are also
useful in high-Q cavities because of their Tow
alternating current losses at high frequencies
compared to those in normal metals.
14
TABLET PrincipalApplicationsof
Superconductivitya
PRESENT APPLICATIONS
Magnets
.
Commercial and industrial uses
Medical diagnostics and research
(magnetic-resonance imaging and
spectroscopy)
Radiofrequency devices (gyrotrons)
-Ore refining
R&D magnets
Magnetic shielding
· Physics machines (colliders, fusion
machines, radiofrequency cavities)
Electronics
· Sensitive accurate instrumentation (super-
conducting quantum interference devices,
infrared sensors)
· Electromagnetic shielding
POTENTIAL APPLICATIONS
(Proven superconducting technology, but no
current market adoption)
Power utility applications
Energy production (magnetohydrody-
namics, magnetic fusion)
Large turbogenerators
-Energy storage
Electrical power transmission
Transportation
High-speed trains (magnetic levitation)
Ship drive systems
Computers
Semiconducting-superconducting
hybrids
Active superconducting elements
aThere are many other potential applications' some of
which are mentioned in the text.
.
Electronic applications for superconduc-
tors usually involve Tow electric currents (al-
though high current densities) and low mag-
netic fielcls. The core element has been a
unique bistable device, the Josephson junc-
tion. Superconductors may also eliminate
resistive current losses in electronic lines and
device interconnections. In addition, vari-
ous kinds of superconducting sensors have
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HIGH- TEMPERATURE S UPER COND UCTIVITY
been produced. ATi of these applications, in-
cluding the assembly of superconducting
electronic components into larger crevices,
will be reconsiderecT with the new com-
pouncls.
Potential applications of high-temperature
superconductors divide into those relevant
to currently available materials with critical
temperatures near 95 K, and those relevant
to possible future materials with higher criti-
cal temperatures. The most exciting possibil-
ities, of course, arise with materials with crit-
ical temperatures above room temperature.
H~GH-F~E~D AND
~ARGE-SCAEE APPLICATIONS
Superconducting magnets using liquid
helium technology have been successfully
applied for a number of years in engineered
systems and development projects in hospi-
tals, mines, industrial plants, laboratories,
and transportation systems. Most of these
applications require multiple technologies,
with superconductivity playing a critical
role.
In medicine, superconductors have been a
significant factor in the clevelopment of
a new market. In high-energy physics,
superconductors have lee! to machines of un-
precedented and previously inconceivable
energy. Tn electric power, potential applica-
tions in energy storage and power trans
. .
mission equipment promise to extend the
capacity and range of current technology.
Superconducting magnets are essential
components in experimental systems for
magnetic fusion and magnetohydrodynam-
ics (MHD). The extremely high power-to-
weight ratio possible for superconducting
machines makes them particularly attractive
for space applications.
For magnet and power applications, the
higher the critical temperature, the smaller
will be the scale at which commercial viabil-
ity will be achieved. As an example, the
power level at which motors ancT generators
become competitive will be much lower than
15
with the present low-temperature supercon-
ductors, when compared to nonsupercon-
clucting machines. A liquid nitrogen-cooled
motor, for instance, operating at modest cur-
rent and magnetic field, might well be
smaller, more efficient, and more reliable for
the same power output than many present-
clay motors.
For most applications the switch from liq-
uid helium to liquid nitrogen technology is
not revolutionary but will lead to improve-
meets. The continued neec! for refrigeration
is a disadvantage and will reduce market
penetration. Of course, the reconsideration
of applications held to be impractical at liq-
uid helium temperatures might lead to new
products. A hollow conductor cooled with
liquic! nitrogen is easy to visualize in practi-
cal use, for instance. It may not be necessary
to demand that the technical specifications
of new materials compete with the best com-
mercial superconducting materials of toclay:
a conductor of modest specifications may
have value in a wicler context than conven-
tional low-temperature superconductors.
The new materials, in short, may not so
much replace present-day superconductors
as extend the applications of superconduc-
tivity to a larger circle of users.
Medical Applications
Magnetic-resonance imaging (MRT) and
spectroscopy (MRS) constitute radically new
techniques in medical diagnosis and treat-
ment, and their full impact is yet to be real-
izecl. Much more widespread availability of
MRT and MRS systems can be anticipated,
with concomitant reductions in cost and en-
hancement of features. The use of high-tem-
perature superconducting materials would
likely bring further small reductions in the
costs of manufacture and operation. The re-
design of MR] and MRS systems with liquid
nitrogen cooling wouIcl also make them
more user-friendly and reliable by reducing
cooling system complexity.
OCR for page 16
Superconducting Radiofrequency Cavities
If microwave alternating current Toss char-
acteristics are tolerable, the new supercon-
cluctors may greatly improve the perfor-
mance of superconducting radiofrequency
cavities by allowing them to operate at
higher fields. Tndeecl, the potential impacts
embrace all of microwave power technology,
especially in the promising millimeter-wave
region. Accelerator technology might also be
significantly advanced by the availability of
~liquicl nitrogen-cooled superconducting cav-
ities. The applicability of superconducting
technology to recirculating linear accelera-
tors, on the other hand, is an accepted fact.
In addition to providing high-quality beams
for nuclear physics research, these machines
are natural canctidates for continuous beam
injectors used in free-electron lasers. As
technology matures anct industrial applica-
tions develop for high-power, high-effi-
ciency tuneable lasers in biotechnology,
fusion plasma heating, and other fields,
superconducting radiofrequency crevices
will proliferate.
Transportation
Ambitious attempts to apply supercon-
ductivity to lane! and ocean transportation
have been made over the years with some
success in the United States, Europe, and la-
pan. In fact, a Japanese magnetic levitation
rail system is available for interested buyers
anc7 is economically viable.
Superconducting ship propulsion systems
were studied in England in the 1960s. The
U. S. Navy successfully installecl a prototype
superconducting drive system on a small
ship in 1980; the clevelopment of a 40,000-
horsepower drive system continues. A sec-
ond concept uses seawater as the working
fluid in an MHD propulsion system; the
drive scheme is known as an electromag-
netic thruster (EMT). Ship models based on
this propulsion principle were promoted in
the United States in the 1960s and operated
in Japan in the 1970s. Practical designs for a
full-scare EMT ship have been proposed,
and industrial collaboration is being sought.
Because the present worldwide systems of
air, sea, and land transportation are well es-
tablished anc! represent a substantial invest-
ment, society has not yet made use of the
potential advantages that have been demon-
strated in prototype transportation systems
using low-temperature superconductors. In
land-based systems the principal advantage
is high speect. Ship-based systems are
lighter, have better speed control, and per-
mit the radical rearrangement of power drive
systems within ship structures. The combi-
nation of room-temperature superconduc-
tors and the low specific volume of super-
conclucting machines could revolutionize
surface transportation.
ELECTRONIC APPLICATIONS
Some of the most promising applications
of high-temperature superconductors are
electronic systems involving thin film lines
or Josephson elements. Applications in com-
puters would have the largest commercial
impact, but may take longer because of their
complexity. Sensor and instrument applica-
tions are simpler and are likely to be com-
mercialized within a few years. Simplest
of all is the use of high-temperature super-
conductors for Tow-field electromagnetic
shielding.
Computers and Logic Devices
Much work has already been carried out
on computer subsystems based on liquid he-
lium superconductors. Semiconductor tech-
nology is still advancing rapidly, however,
and continues to dominate the computer
field. The discovery of high-temperature su-
perconductors may change this situation.
16
OCR for page 17
HIGH-TEMPERATURE SUPERCONDUCTIVITY
One possible role of superconductors in
such systems is simply to interconnect the
semicondiucting devices with superconduct-
ing microcircuit transmission lines. This pos-
sibility is aIreacly interesting at 77 K, because
certain semiconducting devices switch faster
at this lower temperature. However, 77 K
copper lines present significant competition
because of their decreased resistivity com-
pared to that at room temperature.
The most exciting opportunities would
use room temperature superconductors,
offering compatibility with the entire line of
semiconductors, including the highest per-
formance bipolar devices. In the most prom-
ising scenario, the use of room temperature
superconductors could affect the full range
of data processing systems, which form the
largest high-technology industry in the
world tociay.
Although the implications of high-temper-
ature superconductors for semiconducting
computer systems have yet to be assessed,
the reduced losses compared to normal con-
ductors offer many possible advantages.
System performance (i.e., switching speed)
can be increased by reducing the RC time
constant associated with the interconnect
line. Narrower lines can be used, saving
space on the chip. The elimination of power
Tosses and voltage drops permits miniatur-
ization of power busses and potentially,
therefore, of the entire system.
The high-temperature superconductors
have also been proposed for computer appli-
cations using Tosephson junctions. High-
temperature superconductors may offer
higher device switching speeds, higher
bandwidth transmission, and the possibility
of using semiconclucting memory to supple-
ment ultra-high-speed superconducting
logic. The disadvantages of high-tempera-
ture superconductors are increased thermal
noise and switching power losses at 77 K
compared to earlier liquid-helium tempera-
ture designs.
A variety of superconducting transistor
17
like crevices have been proposed, among
them superconducting fielct-effect transis-
tors (FETs), several nonequilibrium devices,
and optically switcher! FETs. These devices
are at early stages of development, even us-
ing the conventional low-temperature su-
perconductors; but although there are still
considerable materials and fabrication prob-
lems, the potential performance of some of
these devices might be enhanced by higher
switching speeds and output voltage
changes stemming from the larger energy
gaps of the high-temperature superconduc-
tors.
SENSORS AND OTHER APPEICATIONS
SQUlDs
Superconducting quantum interference
devices (SQUTDs), operating at liquid he-
lium temperatures as sensitive magnetic
field detectors, are already of value in many
disciplines including medical diagnostics,
geophysical prospecting, undersea commu-
nications, and submarine detection.
SQUTDs made with the new high-tempera-
ture materials have been operated at liquid
nitrogen temperatures. Relatively inexpen-
sive SQUlD-based magnetometers operat-
ing at 77 K or higher would be deployed in
large numbers if electrical noise can be held
to acceptably low levels.
Radiation Detectors
Superconducting microwave and far-in-
frared radiation detectors (quasiparticle mix-
ers, superconducting bolometers) already
exist using conventional superconductors.
in spite of a loss of sensitivity due to in-
creased electrical noise at higher tempera-
tures, the increased energy gap of high-
temperature superconductors would offer
sensitive detection in a largely inaccessible
frequency range, and the simplified refriger
OCR for page 18
ation allows increased ease of use. Other mi-
crowave applications include high-Q wave-
guides, phase shifters, and antenna arrays.
Analog Signal Processors
High-speed analog signal processors per-
forming such functions as filtering, convolu-
tion, correlation, Fourier transformation,
and analog-to-digital (A-to-D) conversion
are important for many applications. Vari-
ous high-speed A-to-D converters have been
tested successfully at 4.2 K. If high-quaTity
Josephson junctions can be fabricated from
the new superconductors, these devices
shouIc! perform comparably at 77 K. At this
temperature, integration of the supercon-
ducting devices with some semiconclucting
devices (for example, complementary metal-
oxide semiconductors becomes feasible,
and new hybrid systems may well result in
the fastest A-to-D converters available.
Magnetic Shielding
Both superconducting wires and super-
conducting sheets have been used for many
years to create regions free from all magnetic
fields or to shape magnetic fielcls. The ad-
vent of high-temperature superconductors
may extend the range of this application.
Like niobium-tin, high-temperature super-
conductors may be plasma-sprayed, permit-
ting their use on surfaces of complex shape.
Voltage Standard
Many countries now maintain a voltage
stanciard in terms of the voltage generated
across a low-temperature superconducting
Josephson junction irradiatect by micro-
waves at a precise frequency. This standard
could be more cheaply maintained and more
widely available with no significant loss of
accuracy by operating at 77 K with the new
materials.
THE PRESENT MARKET FOR
SUPERCONDUCTORS AND LIKELY
CHANGES ASSOCIATED WITH
THE NEW MATERIALS
The world superconductor industry is
small, but superconducting devices are usu-
ally components of larger systems whose
gross annual sales volume is many times the
value of the devices themselves. Annual de-
vice sales total about $400 million, of which
medical imaging machines and electronics
instruments each account for approximately
$150 million. Magnet coils represent 10 to 20
percent of device costs in MRI systems, and
annual sales of basic materials such as alloy
rod and sheet are on the order of $10-$20 mil-
lion.
It is difficult to estimate the potential eco-
nomic impact of today's high-temperature
superconductors because so little is known
about them and much depends on improved
understancling and technological develop-
ment. Assuming that satisfactory concluc-
tors can be manufactured, there are con-
siderable advantages to operation in liquid
nitrogen. Refrigeration units are simpler and
cost less to operate. Conductor stability gen-
erally improves as the temperature increases
because of the higher heat capacity of materi-
als; however, the protective effect of the
shunting normal conductor is reduced
slightly because of its increased resistivity.
Structural materials are less brittle at higher
temperatures; therefore, more conventional
structures can be used. Cryogenic liquicTs
and systems, however, will still be needed.
In comparing superconductor technology
with present room temperature devices, the
need for cooling is a serious economic and
technological disadvantage. There is a great
difference between switching on a machine
as needed and having to supply continuous
refrigeration, or having to wait for refrigera-
tion systems to reach operating tempera-
tures.
Assuming that some utility and heavy
18
OCR for page 19
HIGH-TEMPERATURE SUPERCONDUCTIVI7 Y
electric power applications can be competi-
tively marketed using systems cooled by liq-
uid nitrogen, the superconducting materials
market may be substantially increased; the
market for heavy electrical equipment, how-
ever, would be mainly a replacement one,
because few new systems are being built.
For substantial business growth above that
projected for low-temperature supercon-
ductors, new technology developments are
needed. There is little doubt that the new
materials offer technological advantages, for
they promise high-magnetic-field devices
and new types of electronic sensors and
switches at lower refrigeration costs than be-
fore. The panel is unanimous in stating that
advances are bound to result in new applica-
tions and new economic growth. If room
temperature superconductors become avail-
able, we can confidently expect a truly revo-
lutionarv expansion of superconducting
~ ~ 1
applications in electrotechnology.
THE GLOBAL PICTURE:
SUPERCONDUCTIVITY CAPABILITIES
IN OTHER COUNTRIES
On a global scale, today's world supercon-
ductor industry is small but mature and prin-
cipally confined to the developed countries.
Basic research capabilities are more wide-
spread.
Although much of the early impetus for re-
search and development came from the
United States, technology transfer has not
been unidirectional. National and interna-
tional conferences on all aspects of low-tem-
perature physics have become routine.
Over the past 25 years, in several countries
a wide variety of applications of supercon-
ducting electrotechnology have been exam-
ined in prototype development programs.
No replacements for conventional applica-
tions have reached the market, however. As
a result the demand for superconducting
materials has been relatively small and has
lacked continuity, being largely oriented to
19
ward development. Nevertheless, in most
countries, government programs have sup-
ported a fledgling industry.
In the United States, magnet development
for high-energy physics machines has been
carried out in the national laboratories. Fu-
sion and MHD magnets have been built both
in the national laboratories and in private in-
dustry. There is also a rapidly growing com-
mercial market based mainly on new medi-
cal imaging systems. A small materials and
wire industry serves magnet development
efforts. Many U. S. firms have supported
their own research and development efforts
in superconductor technology, both for
power and electronic applications. A few
small, continuing ventures have succeeded
in superconducting electronics; a large mar-
ket for superconducting electronic devices or
systems has not yet developed.
Corporations in Europe and Japan have
also fostered and maintained an expertise in
superconductivity. In those nations, foreign
governments have to some degree protected
their superconductor industries by ensuring
that equipment for government laboratories
is built by domestic private industry; foreign
bids are not accepted, a policy that ensures
national industrial expertise. By compari-
son, much of this work in the United States is
carried out in the federal laboratories from
which there is little transfer to industry. In
addition, foreign superconductor firms are
allowed to bid on equipment needed by the
United States government.
The USSR also has aggressive, long-term
programs in energy conservation (including
superconducting power transmission and
storage), fabrication of superconducting
wires and tapes, electronics, collider con-
struction, magnetic fusion, magnetohydro-
dynamics, and superconducting generators.
Over the years, the United States has pro-
vided world leadership in superconducting
science and technology, and has generously
shared its own technology with other na-
tions. Current collaborative efforts include
OCR for page 20
the International Large Coil Fusion Project at
Oak Ridge National Laboratory and lapa-
nese development of a very large detector
magnet for the Fermilab collider interaction
area. In the evaluation of conductors for the
physics collider magnets (the Superconduct-
ing Super Collider and the heavy-ion colli-
der), material has been purchased fromiapa-
nese and European firms. The United States,
through Brookhaven National Laboratory,
also provides test evaluations of cables ant!
conductors for the Hadron Electron Ring
Accelerator (HERA) collider under construc-
tion in Hamburg, West Germany. Two pro-
totype magnets for the Relativistic Heavy-
Ton Collider (RHTC) have been purchased
from the Brown Boveri Corporation (West
Germany) because this was the cheapest and
quickest way to obtain them (Brown Boveri
had the necessary tooling because of their
work for HERA).
BASIC H~GH-TEMPERATURE
SUPERCONDUCTING RESEARCH
Basic research in high-temperature super-
conductivity is being actively pursued in all
of the developed nations mentioned above
and in several developing nations. In most
cases scientists have switched spontane-
ously from other scientific activities into
high-temperature superconductivity re-
search. To this point, however, little new
money has gone into basic research efforts.
Plans are being prepared for 198S, but at
present no major new government resources
have been committed. The prevailing atti-
tude appears to be that of waiting to see how
the science progresses.
In Japan the scientific and technical com-
munity has responded vigorously, but aside
from reprogramming there has been modest
immediate additional action by government
agencies. The latter have, however, been
quite active in formulating plans for the next
fiscal year (which begins in April 1988~. Pri-
vate industrial corporations are said to be in-
vesting their own funcis heavily in research
20
on high-temperature superconductors, with
the government intervening to establish in-
dustry consortia to pursue prototyping and
other early development activities. Japan of-
fers perhaps the strongest long-range com-
petitive threat to the U. S. position.
In Europe, historical strengths in basic re-
search and industrial development are being
applied to the new superconductors. Na-
tional and cross-national efforts are in the
early organizational stages at best (again,
with the exception of the reprogramming of
research funds), and major project goals to
drive technical problem solving are not yet in
place. On the other hand, a variety of indus-
trial corporations are involved in research,
and precompetitive collaborations appear to
be at advanced planning stages.
In the USSR, traditional scientific
strengths in superconductivity theory and
basic experimental approaches are being ap-
plied to the new materials. In addition, work
is being carried out on the susceptibility of
high-temperature superconducting materi-
als to radiation damage.
SUMMARY OF PANEL VIEWS AND
RECOMMENDATIONS
STATUS OF SCIENCE AND TECHNOLOGY
· The discovery of materials that exhibit
superconductivity at temperatures up to
95 K is a major scientific event, certainly one
of the more important of the last decade.
Meeting the complex challenge of under-
standing the phenomenon will improve fun-
damental knowledge of the electronic prop-
erties of solids.
· Although a large number of promising
theories are being explored, there is as yet no
generally accepted theoretical explanation of
the high critical temperature behavior. Cur-
rent theoretical understanding does not pre-
clude TCS above 95 K.
· The base of experimental knowledge on
the new superconductors is growing rap
OCR for page 21
HIGH- TEMPERATURE S UPER COND UCTIVITY
idly. The intrinsic properties that can guide
theory are still being determined. A number
of investigators have reported supercon-
ducting-like transitions at temperatures
above 95 K, in some cases even above room
temperature; at present those effects have
not been firmly established.
· The prospect exists for applying the new
superconductors to both electrical anct elec-
tronic technology. The nature of the new ma-
terials (quaternary ceramic oxides) suggests
that a substantial materials engineering ef-
fort will be required to develop bulk conduc-
tors for power applications or thin films for
electronic applications.
· The applications currently being consid-
ered are largely extrapolations of technology
already under investigation for lower tem-
perature superconductors. To create a larger
scope of applications, inventions that use
the new materials will be required. Given the
materials engineering problems already
mentioned, the period of precommercial ex-
ploration of the new superconductors for
other applications will probably last for a
decacle or more. Although it is too early to
make a sound engineering judgment about
most of the possible high-temperature
superconductivity applications, the poten-
tial impact could be enormous, especially if
operation at room temperature can be
achieved.
· Near-term prospects for high-tempera-
ture-superconductivity applications inclucle
magnetic shielding, the voltage standard,
SQUTDs, infrared sensors, microwave de-
vices, and analog signal processing. Longer-
term prospects include large-scare applica-
tions such as microwave cavities; power
transmission lines; and superconducting
magnets in generators, energy storage de-
vices, particle accelerators, rotating machin-
ery, medical imaging systems, levitated
vehicles, anti magnetic separators. In elec-
tronics, long-term prospects include com-
puter applications with semiconductin~-su-
perconducting hybrids, Josephson devices,
or novel transistor-like superconducting de
21
vices. Several of these technologies will have
military applications.
· The complexity of the materials technol-
ogy and of many of these applications makes
a long-term view of research and develop-
ment essential for success in commerciaTiza-
tion. The infectious enthusiasm in the press
and elsewhere may have contributed to pre-
mature public expectations of revolutionary
technology on a very short time scale. Over-
reaction in either ctirection could be detri-
mental to achieving the true long-term
potential of high-temperature supercon-
ductivity.
THE UNITED STATES AND THE
WORLD SITUATION
· Although the initial high-temperature
superconductivity discovery was made in
the Swiss research laboratory of IBM, the
next advances occurred very soon afterward
in the United States. These advances were
the synthesis of 1-2-3 compounds with TCS of
up to 95 K. Before the constituents of the ma-
terial were known, inclependent discoveries
of the superconducting behavior of these
compounds were also made in China and la-
pan a few days later.
· The United States has a good competi-
tive position in the science of this field. it has
also shown flexibility; scientists in universi-
ties and industrial and government laborato-
ries have spontaneously switched into this
field from their previous endeavors and
have contributed significantly to the worId-
wide expansion of scientific knowledge on
the new superconductors. Nevertheless,
there is concern about the effectiveness of
the nation's capabilities for translating this
research strength into commercial products.
· The U. S. government has already repro-
grammed close to $30 million of research
funds for high-temperature superconductiv-
ity work in universities and industrial labo-
ratories for fiscal year 1987. We estimate that
at least an equivalent amount of private
funds are being expended by U.S. corpora
OCR for page 22
lions. Total annual funding levels will proba-
bly be in the range of $100-$200 million by
1988, although firm figures for ind~trv ore
not available.
~,
· ~ nese expenditures will expand the U. S.
graduate and postgraduate population
working in areas relevant to high-tempera-
ture superconductivity and will create pres-
sures on the nation's scientific manpower
pool.
· The rapid dissemination of scientific
results has occurred mainly through word of
mouth, preprints, and press releases, re-
flecting the close-knit global community of
scientific endeavor. At present there are
hardly any restrictions on the flow of infor-
mation throughout the world.
· international competition in high-tem-
perature superconductivity is intense. The
leading industrialized countries, especially
the Unitecl States, Japan, several Western
European countries, and the USSR have
mounted substantial scientific and techno-
logical efforts.
· Should successful technologies emerge
from the discoveries in high-temperature su-
perconductivity, the Unitec! States has many
of the ingredients needed to develop and
commercialize those technologies. Whether
this will result in business success for U.S.
corporations in the global market will de-
pend not only on technological factors but
also on company business strategies and a
range of government policies. The panel is
not qualified to address these latter issues
comprehensively but has made some recom-
mendations, listed below, that should assist
commercialization.
FURTHER PROGRE S S: THE NEXT STEPS
The short-term problems and Tong-term
potential of high-temperature superconduc-
tivity may both be easily underestimated.
Given this potential and today's limited un-
derstanding of the new superconducting
materials and their properties, it is essential
that government, academic institutions, and
22
industry take a long-term, multidisciplinary
view. Because science and technology in this
field are strongly intertwined, progress must
occur simultaneously in basic science, man-
ufacturing processing science, and engi-
neering applications. It is also important to
maintain an open and cooperative interna-
tional posture.
Scientific and Technological Objectives
The panel has identified eight major scien-
tific and technological objectives for a na-
tional program to exploit high-temperature
superconductivity. They are:
I. to improve understanding of the essen-
tial properties of current high-temperature
superconducting materials (especially Tc,
HC2, Jc, and alternating current Tosses)
through the acquisition of additional experi-
mental data;
2. to develop an understancling of the ba-
sic mechanisms responsible for supercon-
ductivity in the new materials;
3. to search for additional materials exhib-
iting superconductivity at higher tempera-
tures by the synthesis of new compositions,
structures, and phases;
4. to prepare thin films of controllable and
reproducible quality from present high-tem-
perature superconducting materials, and es-
tablish preferred techniques for growing
films suitable for electronic device fabrica-
tion;
5. to develop bulk conductors from cur-
rent high-temperature superconducting ma-
terials, with special emphasis on enhanced
electric current-carrying capacity;
6. to advance the understanding of the
chemistry, chemical engineering, and ce-
ramic properties of the new materials, focus-
ing on synthesis, processing, stability, and
methods for large-scare production;
7. to fabricate a range of prototype circuits
and electronic crevices based on supercon-
ducting microcircuits or hybrid supercon
OCR for page 23
HIGH-TEMPERATURE SUPERCONDUCTIVITY
ductor/semiconductor circuits, as suitable
thin film technologies become available; and
8. to fabricate a range of prototype high-
field magnets, alternating- and direct-cur-
rent power devices, rotating machines,
transmission circuits, and energy storage
devices, as suitable bulk conductors are de-
veloped.
PANEL RECOMMENDATIONS
The panel recommends that the following
actions be taken to carry out the objectives
listed above:
· The U.S. government should proceed
with its plans to provide funding for high-
temperature superconductivity research
and development on the order of $100 mil-
lion for fiscal year 1988. This funding level
represents a good beginning in addressing
the challenges and opportunities offered bv
the new materials.
1 ~- - - ~
· Sufficient new money must be provided
to both the science and the technology of
high-temperature superconductivity so that
other important and promising areas of re-
search and development are not held back.
· A mechanism should be established to
monitor the potential demand for increased
scientific and technical manpower in the
event that the promise of high-temperature
superconductivity is fully realized, and to
23
formulate appropriate recommendations on
the funding of U. S. graduate and postgradu-
ate research programs.
· An interagency mechanism should be
established to help coordinate planning for
superconductivity programs among the var-
ious federal agencies.
· Given the anticipated rate of advance in
high-temperature superconducting science
and technology, the federal government
should review progress in the field after 12
months as a guide to future resource alloca-
tion.
· Through its agencies the U.S. govern-
ment must enhance the probability that U. S.
industry gains a competitive advantage in
this new field. This could be accomplished
by the close association of industry with the
Engineering Research or Science and Tech-
nology Center programs of the National Sci-
ence Foundation, by cost-sharing between
government and industry on proof-of-con-
cept projects, and by other joint efforts.
· An important mechanism for enhancing
U.S. industry's position is improved tech-
nology transfer from the national laborato-
ries to the private sector. Although a variety
of means are already in place to encourage
such transfers, the panel is concerned about
the effectiveness of past efforts and urges
both government and industry to pursue
linkages more aggressively.
OCR for page 24
Representative terms from entire chapter:
liquid helium
