Some basic questions of the way which leads from the discovery of high-T(c) superconductors to their applications is surveyed. The influence of high-T(c) superconducting technology on the industrial and social development is also briefly analyzed

Bencze, L.

Goebl, N.

Horvath, E.

Kirschner, I.

Vajda, I.

English

NASA Technical Reports Server

mGH-T SUPERCONDUCTORS: TECHNICAL AND COMMERCIAL
CHALLENGE
I. Kirschner _), E. Horv_ith_2),I. Vajda_), L. Bencze_4)and N. Giibl_4)
(1) Department for Low Temperature Physics, EOtvOsUniversity, Budapest, Hungary
(2) EPOS-PVI, Inc., Budapest, Hungary
(3) Department of Electrical Machines, Technical University, Budapest, Hungary
(4) Research Institute for Electrical Industry, Budapest, Hungary
Abstract
Somebasicquestionsof the way, whichleadsfrom the discoveryof high-Tosuperconductors
to their applications is surveyed. The influenceof high-T_superconductingtechnology on the
industrialand socialdevelopmentis also brieflyanalysed.
General
The main problems are how the results of the scientific research can be transferred
"into technology and in what extent this process can be useful for the society.
Postulation: Superconductivity, as a phenomenon of extremely or ideally lossless state
should revolutionize not only the electrical or electronical industry, but through them it
should change various segments or sections of technology and the life style of the society
too.
The fact: There are certain obstacles (requirement of cooling, critical parameters
themselves, a.c. losses, etc.) those make difficult to introduce the physical findings, results
and developments into technology.
Disappointments: Some potential users, evenprofessionals (engineers, managers, etc.)
are often deeply disappointed when they are aware of the difficulties.
Financing : Both of basic and technical researches require sponsors who are able and
eager to invest money into a scientific program without the requirement of making profit
within a short term. Govemments and companies of developed countries wish to sponsor
these themes, but in an other part of countries there is a lack of money to support the
superconductivity research.
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Usefulness: The new technology induced by the research of superconductivity results
in new and efficient modes of production. This leads to bring forth new values for the
society.
Superconducting products
Fifty years were necessary after the discovery of conventional superconductivity [1]
until the first attempt [2] to elaborate some magnetic application of this phenomenon. The
main difficulty is represented by complicated and expensive liquid helium technique which
strongly limits the spread of low-temperature superconductors.
A qualitatively new situation appeared by the discovery of high-temperature
superconductivity [3], for which the simple and cheap cooling provided by liquid nitrogen
is sufficient. Until this date five groups of oxide ceramics can be taken into consideration
from the point of view of technical employment, namely La-Ba-Cu-O, Y-Ba-Cu-O,
Bi(Pb)-Sr-Ca-Cu-O, T1-Ca-Ba-Cu-Oand Hg-Ba-Ca-Cu-O families having intervals of critical
temperature Tc of 32-40 K, 80-92 K, 85-110 K, 60-125 K and 90-150 K, respectively.
As far as the other two main parameters are concerned, the upper critical magnetic field He2
falls into interval of 50-200 T, while the transport critical current density Jc extremely
depends on the morphological character of the samples [4], having values of 100-300 A/cm2
for bulk materials, 103-105A/cm2 for melt-textured thick films and 105-106A/cm2 for high
quality thin layers.
The reliable and controlled best values of Jofor 100-200 m long wires and tapes are
50000-100000 A/cm2 for Y-based, 50000-150000 A/cm2 for Bi-based materials, while
10000-20000 A/cm_ can be reached for very pure Tl-based short samples. Since some of
these superconductors can work in a very high (5-25 T) magnetic field, the possibility of
their use for different electrotechnicalpurposes can be taken to be acceptable.
The problem of rigid andbrittle properties of these ceramics and the question of long
time stability seems to be soluble.
The most probable applicationsof these materials concern not only the electrical
industry, but the electronics, signalprocessing, computer techniqueand informatics too, as
is listed in the followings [5]:
1. building magnetsand magneticshieldings,
2. generators, electrical transport lines, magneticenergy storage,
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3. fault current limiters,
4. heavy-duty bearings,
5. magnetically levitated machines,
6. sensors for temperature, pressure, magnetic field, frequency, voltage, current, liquid level,
radiation, etc.,
7. signal detectors and processors,
8. electronical chips,
9. high frequency receivers, mixers and antennas,
10. fast computers,
11. bolometers and nuclear particle detectors, etc.
New developments: Proposals and experiments regarding technical applications of
high-To superconductors should compete with existing and reliable products. The new
products should have some advantages to substitute the present ones.
Most successful applications have been developed in those fields of technology, where
there are no real competitive counterparts.
Commercial challenge
The commercial challenge arises when superconducting products are at the society's
disposal in an appropriate quality and quantity and they should be distributed among the
demanding institutions and persons by selling and buying. Nowadays we are far from this
point, but the society must be prepared to this one, because the new materials, products,
instruments and equipments will change the style and quality of the life.
Superconductivity and society
How to influence the society in order to accept easier the novel and unique results of
the science and technology?
We think there is a lack of a thorough analysis of economic and social effects of the
technology of superconductivity. This analysis must be accomplished by ourselves and its
results should be submitted to the decision-making persons.
It is obvious that we are responsible to introduce the teaching of basic and applied
58
aspectsof superconductivityinto the educationof the universitiesand secondaryschools or
to improve theireducation.Numerousprojectsaimedat the applicationof superconductivity
are planned to be partly or fully completedby the end of this century. By this time the
studentswho will study the superconductivityin the next years will come to work into the
industry, economy, etc., and perhaps theywouldbe moresusceptibleto new technologies,
like superconductivity.
References
1. K. H. Onnes, Comm. Phys. Lab. Univ. Leiden N° 119. 122. 1911.
2. J. E. Kunzler, E. Buehler, F. S. L. Hsu and J. H. Wernich, Phys. Rev. Lett. 6. 89.
1961.
3. J. G. Bednorz and K. A. MOiler, Zeit. Phys. B64. 189. 1986.
4. I. Kirschner, Appl. Supercond. 1. 1785. 1993.
5. I. Kirschner, S. Lepp_ivuori, T. Porjesz, A. Uusim_ikiand T. Kokkom_ki, Sensors and
Actuators A41. 58. 1994.
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High T(c) superconductors: Technical and commercial challenge

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