Research Briefings 1987 (1988) / Chapter Skim
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Report of the Research Briefing Panel on High-Temperature Superconductivity
Report of the Research Briefing Panel on High-Temperature Superconductivity
Pages 1-24
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Report of the Research Bnefing Panel on High-Temperature Superconductivity
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Larbalestier, Associate Director, Applied Superconductivity Center, Department of Metallurgical Engineering, University of Wisconsin, Madison Charles Laverick, Private Consultant, Patchogue, N.Y. Alexis P
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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
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Near-term prospects for applications of high-temperature superconducting materials include magnetic shielding, the voltage standard, superconducting quantum interference devices, infrared sensors, microwave crevices, and analog signal processing. T onger-term prospects inclucle large-scare applications such as microwave cavities; power transmission lines; and superconducting magnets in generators, energy storage devices, particle accelerators, rotating machinery, medical imaging systems, levitated vehicles, and magnetic separators.
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to fabricate a range of prototype highfield magnets, alternating and direct current power devices, rotating machines, transmission 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.
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This could be accomplishec! by the close association of industry with the Engineering Research or Science and Technology Center programs of the National Science Foundation, by cost-sharing between government and industry on proof-of-concept projects, and by other joint efforts.
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, a temperature accessible only through immersion in liquid helium. In 1913 Onnes also found that weak magnetic fields (of a few hundred gauss)
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, can support even larger electric currents and remain superconducting in higher magnetic fields, but it has found much less use because of its brittle nature. Other materials have found more limited uses for example, pure niobium in radiofrequency cavities and niobium nitride (NbN)
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Indeed, some theorists have discarded conventional BardeenCooper-Schrieffer theory and have suggested that there may not even be the traditional 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 secrets of these compounds.
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CriticaZ Current Density, fc For practical applications, k values in excess of 103 amperes per square millimeter (A/mm2) , are desirable both in bulk conductors for power applications and in thin film superconductors for microelectronics.
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with strain tolerance of 0.5 percent, and availability at prices comparable to or less than those of conventional Tow-temperature superconductors. Preliminary measurements on epitaxially grown single-crystal thin films indicate lc values in excess of )
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. Alternating Current Losses Conventional superconductors exhibit losses in alternating current applications, such as in 60 Hertz power transmission or in microwave devices.
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-Ore refining R&D magnets Magnetic shielding · Physics machines (colliders, fusion machines, radiofrequency cavities) Electronics · Sensitive accurate instrumentation (superconducting quantum interference devices, infrared sensors)
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A liquid nitrogen-cooled motor, for instance, operating at modest current and magnetic field, might well be smaller, more efficient, and more reliable for the same power output than many presentclay motors. For most applications the switch from liquid helium to liquid nitrogen technology is not revolutionary but will lead to improvemeets.
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ELECTRONIC APPLICATIONS Some of the most promising applications of high-temperature superconductors are electronic systems involving thin film lines or Josephson elements. Applications in computers would have the largest commercial impact, but may take longer because of their complexity.
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SENSORS AND OTHER APPEICATIONS SQUlDs Superconducting quantum interference devices (SQUTDs) , operating at liquid helium temperatures as sensitive magnetic field detectors, are already of value in many disciplines including medical diagnostics, geophysical prospecting, undersea communications, and submarine detection.
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Magnetic Shielding Both superconducting wires and superconducting sheets have been used for many years to create regions free from all magnetic fields or to shape magnetic fielcls. The advent of high-temperature superconductors may extend the range of this application.
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, fabrication of superconducting wires and tapes, electronics, collider construction, magnetic fusion, magnetohydrodynamics, and superconducting generators. Over the years, the United States has provided world leadership in superconducting science and technology, and has generously shared its own technology with other nations.
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· 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. Current theoretical understanding does not preclude TCS above 95 K
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· Near-term prospects for high-temperature-superconductivity applications inclucle magnetic shielding, the voltage standard, SQUTDs, infrared sensors, microwave devices, and analog signal processing. Longerterm prospects include large-scare applications such as microwave cavities; power transmission lines; and superconducting magnets in generators, energy storage devices, particle accelerators, rotating machinery, medical imaging systems, levitated vehicles, anti magnetic separators.
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to search for additional materials exhibiting superconductivity at higher temperatures by the synthesis of new compositions, structures, and phases; 4. to prepare thin films of controllable and reproducible quality from present high-temperature superconducting materials, and establish preferred techniques for growing films suitable for electronic device fabrication; 5.
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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 hightemperature superconductivity research and development on the order of $100 million for fiscal year 1988.
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