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Several exciting major developments have changed the field of applied superconductivity since 1981, when the first edition of this text was published. New materials and fabrication methods and innovative device and circuit concepts have made profound changes in the way we practice in this field. The most public of the changes was the discovery in 1986 of high-temperature oxide superconductors, several of which quickly were shown to have transition temperatures above the boiling point of nitrogen. Equally important but less publicly obvious was a pair of key innovations in the fabrication of superconductive integrated circuits. A way of making high quality, durable niobium tunnel junctions and a procedure to avoid any processing steps intervening in the fabrication of the junctions, has led to stable, well controlled integrated circuits. New concepts in superconductive detectors and mixers has made superconductivity the technology of choice in millimeter wave radio astronomy. And in the digital field, innovative ideas for single flux quantum logic and for hybridization with semiconductor devices have brought new opportunities. To date, the high-temperature superconductors have had their major impacts in magnetometers and microwave receivers. The greatly reduced refrigerator burden when using these materials compared with the metal superconductors has stimulated very extensive research on making cables for extremely high field magnets, and optimism for use in power systems.
The basic theory of superconductivity we presented in the 1981 edition is still very useful. There is, as yet, no accepted theory of electron pairing in the high-temperature superconductors and much of the practical work, including that on high-temperature superconductors, still relies on the theories in this book. Phenomenological theories have been developed to explain the behavior of high-temperature superconductors. And the low-temperature metallic superconductors continue to be of major importance, not least because of the success of Nb-Ti alloy in MRI magnets, by far the largest commercial market for superconductors. The low-temperature superconductor wire technology has matured over the past two decades and continues to make impressive progress. On the other hand, the fast pace of development of the physics and technology of the high-temperature superconductors presents us with a difficult choice. We have chosen to present a practical view of the current position, but freely admit that new results in this rapidly changing field may lead to a complete reappraisal.
Between us two co-authors, we have had several decades of experience with applications of superconductivity, both in the university and in industry. We have attempted to infuse the presentations, particularly of the electronics part, with our practical views that we hope will be helpful to the readers.
We thank several colleagues in the field including John Clarke, James Lukens, V. K. Kaplunenko, William McGrath, Oleg Mukhanov, Paul Richards, Andrew Smith, Stephen Whiteley, Yongming Zhang, who were very helpful with suggestions on sections in their areas of special expertise and in providing valuable data. Feedback from numerous students over the years has helped to form the presentations.
The need to prepare camera-ready copy for this edition led to the involvement of a large number of people in the Department of Electrical Engineering and Computer Sciences at the University of California, Berkeley, to whom we are deeply grateful. We appreciate their generous giving of time and talent. Carol Sitea was responsible for a part of the typing, inserting scores of figures into the text and making corrections, managing the computer aspects of the project, and finally pulling the manuscript together. Thank you Carol! We appreciate that Joyce McDougal generously organized the staff and participated in the typing of several chapters. Invaluable was the volunteered help from Christine Colbert, Dianna Bolt, and Jay Ento, each of whom typed several chapters. Jennifer Basler's help is appreciated. George Chien played a key role in assembling and modifying some of the most changed chapters.
Important computations were carried out by Yiqun Phillip Xie and Lizhen Zheng and Mark Jeffery provided valuable assistance. The artistic and computer talents of Katherina Law came together to create close to one hundred new figures, matching them in style to those of the first edition. The willing help of Luis Vasquez in carefully scanning hundreds of figures from the first edition and doing extensive library research were essential to the timely completion of the project, and greatly appreciated. Even our wives, Janice and Shan, volunteered help in proofreading and other ways; how can we thank them enough? Getting this edition into camera-ready form has truly been a community project and we are thankful to all who had a role.
T. Van Duzer, Berkeley
C. W. Turner, London --This text refers to the Paperback edition.