Superconductor Applications: SQUIDs and Machines, Softcover reprint of the original 1st ed. 1977 NATO Science Series B: Series, Vol. 21

This book includes small and large scale applications of super­ conductivity. Part I, SQUIDs, comprises about 75% of this volume, and is devoted to small scale applications, mainly .§uperconducting QUantum Interference Devices (SQUIDs), and the remainder, Part H, Machines, presents an updated review of large scale applications of superconduc­ tivity. The present book combined with the previous book Superconducting Machines and Devices: Large Systems Applications edited by S. Foner and B. B. Schwartz, Plenum Press, New York (1974) represents a detailed and most up-to-date review of the applications of superconducting tech­ nology. The text of the current book is suitable for advanced undergrad­ uates or graduate students in applied physics and engineering courses. The book should be valuable to scientists, engineers and technologists interested in the current status and future applications of superconduc­ tivity technology. The last 7 chapters in Part I review the major nation­ al efforts on small scale technology and should prove useful for industrial and government planners as weIl as scientists and engineers.

I — Squids.- 1: The Historical Context of Josephson’s Discovery.- History.- 2: Macroscopic Quantum Phenomena in Superconductors.- I. Introduction.- A. Meissner Effect and Flux Quantization.- B. The dc Josephson Effect.- C. The Critical Current Through a Double Point Contact as a Function of the Applied Magnetic Field.- II. AC Quantum Effects.- A. Extension of the Two-Fluid Interpretation of the London Theory.- B. The ac Josephson Effect.- III. Resistive States in Wear Link Junctions.- A. The Current-Voltage Characteristics and the Resistive-Superconductive Region of a Single Superconducting Weak Link.- B. The Double Point Contact in the Resistive Superconducting Region, the dc SQUID.- 3: Superconducting Quantum Interference Devices for Low Frequency Measurements.- I. Introduction.- II. Superconductivity and the Josephson Effects.- A. Flux Quantization.- B. The Josephson Equations.- C. Types of Josephson Junctions, and their Current-Voltage Characteristics.- III. Dc SQUID.- A. Theory of the dc SQUID.- B. Operation of the dc SQUID.- C. Theory of Noise in the dc SQUID.- D. Practical dc SQUIDS: Fabrication and Performance.- E. Future Improvements in the dc SQUID.- IV. RF SQUID.- A. Theory of the rf SQUID.- B. Operation of the rf SQUID.- C. Noise in the rf SQUID.- D. Practical rf SQUIDS: Fabrication and Performance.- E. Future Improvements in the rf SQUID.- V. Squids as Magnetometers, Gradiometers, Susceptometers, and Voltmeters.- A. Flux Transformer.- B. Measurement of Magnetic Field.- C. Measurement of Magnetic Field Gradient.- D. Measurement of Magnetic Susceptibility.- E. Measurement of Voltage.- VI. Practical Applications of Squid-Based Devices.- 4: Equivalent Circuits and Analogs of the Josephson Effect.- I. Introduction.- II. Small Junctions.- A. Model of the Supercurrent Flow.- B. Voltage Biased Model.- C. Stewart-McCumber Model.- 1. Circuit equations.- 2. Mechanical analogues.- 3. I- curves.- 4. Plasma oscillations.- 5. Punchthrough.- 6. Interaction with rf currents.- D. Inductively-Connected External Elements.- 1. Circuit and mechanical analogues.- 2. Resistive shunts.- 3. Capacitive shunts.- 4. ac SQUID.- E. The de SQUID.- III. Large Junctions.- A. Two-Dimensional Systems.- 1. Circuit models.- 2. Two-dimensional mechanical analog.- B. One-Dimensional Junctions.- 1. Circuit equations.- 2. Mechanical analogue.- 3. Small oscillations and displacements.- 4. Magnetic diffraction and Fiske modes for $$e\gg{\lambda _J}$$.- 5. Junctions $$e\gg{\lambda _J}$$ having vortices and critical currents.- 6. Magnetic field behavior for $$e\gg{\lambda _J}$$.- 7. Vortex motion.- 8. Resonant vortex propagation.- 9. Finite behavior for $$e\gg{\lambda _J}$$.- 10. Vortex oscillations.- IV. Conclusions.- 5: Superconducting Devices for Metrology and Standards.- I. Introduction.- II. Voltage Standards.- A. The SI Volt.- B. Standard Cells and the Defined Volt.- C. The Josephs on Effect and e/h.- D. Practical Josephson Voltage Standards.- E. The Microwave Signal Source.- F. The Josephson Junction.- G. Shielding, Filtering, and Tempering.- H. Theoretical Uncertainty.- I. Present Activities.- III. Current Comparators and Ratio Measurements.- A. Resistive Networks.- B. Inductive Devices.- C. Cold Resistive Dividers.- D. Superconducting Inductive Current Comparators.- IV. Measurements of Rf Power and Attenuation.- A. Some General Remarks on RF and Microwave Measurements.- B. The SQUID as an RF Measuring Device.- C. Practical SQUIDs for RF Metrology.- D. The Measurement of Attenuation.- E. The Measurement of Power.- F. Systematic Errors.- V. Thermometry.- A. The Kelvin Scale Below 1 K.- B. Noise Thermometry with SQUID Sensors.- C. Magnetic Thermometry with SQUIDs.- D. Superconducting Fixed Points.- VI. Measurements of Frequency.- A. The Stability of Oscillators.- B. Oscillators with Superconducting Cavity Resonators.- C. Far Infrared Frequency Synthesis.- D. Recent Work.- 6: High Frequency Properties and Applications of Josephson Junctions from Microwaves to Far-Infrared.- I. General Properties of Josephson Junctions for High Frequency Applications.- A. High Frequency Fundamental Properties of the Ideal Josephson Junction.- B. The Parallel Impedance of Real Josephson Junctions.- C. Limiting Factors of Josephson Junctions at High Frequencies.- 1. Frequency limitation related to the physical mechanism.- 2. Geometrical structure and coupling.- 3. Thermal effects.- 4. Noise.- D. The Main Detection Mechanism.- 1. Wide band detection.- 2. Narrow band detection (linear).- E. The Josephson Junction and Parametric Amplification.- F. The Real JJ Analyzed with the RSJ Model.- 1. Voltage source model.- 2. The current source model.- 3. An important example: the Josephson heterodyne mixer with an external oscillator.- G. Noise.- 1. Physical origin of fluctuations in Josephson junctions.- 2. Josephson junction response in the presence of fluctuations.- H. Noise Temperature, Minimum Detectable Temperature, NEP.- 1. Noise temperatures.- 2. System sensitivity.- I. Coupling and Impedance Matching.- 1. General remarks.- 2. Impedance matching.- 3. Signal input coupling.- II. Analysis and Performances of High-Frequency Josephson Devices.- A. Generation of Radiation.- B. Bolometer.- 1. Bolometer characteristics.- 2. SNS and superconducting transition edge bolometers.- 3. Comparison of devices.- C. Video Detection.- 1. Junction quadratic response.- 2. Voltage response in the general case.- 3. Noise equivalent power.- 4. Discussion of experimental results and comparison with other video detectors.- D. Heterodyne Detection.- 1. External local oscillator.- 2. Internal local oscillator.- 3. Discussion of the results and comparative performances of other mixers.- E. Parametric Amplification.- 1. Parametric amplification with self-pumped JJ.- 2. Externally pumped JJ parametric amplifier.- 3. Discussion.- F. Conclusions.- 7: Fabrication of Josephson Junctions.- I. Introduction.- II. Fabrication Technology.- A. Evaporation Masks.- B. Photolithography.- C. Electron Lithography.- D. Thin-Film Deposition and Ion Etching.- III. Sandwich-Type Junctions.- A. Oxide-Barrier Junctions.- B. Evaporated Semiconductor Barrier Junctions.- C. Single-Crystal Silicon-Membrane Junctions.- IV. Junctions with Coplanar Electrodes.- A. Variable-Composition Junctions.- B. Semiconductor Bridge.- C. Microbridges.- V. Point Contacts.- 8: Biomagnetism.- I. Introduction.- II. Forward and Inverse Problems.- III. Squid Measurement Techniques.- IV. Magnetocardiogram.- V. Fetal Magnetocardiogram.- VI. Magnetomyogram.- VII. Magneto-Oculogram.- VIII. Magnetoencephelogram.- IX. Visually Evoked Field.- X. Expectations.- 9: A Progress Report on Commercial Superconducting Instruments in the United States.- I. Introduction.- II. SQUID Sensors.- III. Laboratory Probes.- IV. Geophysical Magnetometers.- V. Magnetic Anomaly Detectors.- VI. Biomedical Magnetometers.- VII. Sample Measuring Instruments.- VIII. Shielded Environments.- IX. Conclusions.- 10: Resistive Devices.- I. Introduction.- II. The ‘Corresponding’ SQUID.- III. The RSQUID and its ‘Corresponding’ SQUID.- IV. Behavior when Modulation Currents I and im are ABSENT.- A. Stable and Unstable Equilibrium.- B. Deviations from the Standard Behavior.- C. The Form of Ik (?j).- D. Fluctuations about Equilibrium.- E. Behavior when I is small.- V. Experiments with External Current I (AC or DC).- VI. Applications of RSQUIDs.- A. Types of RSQUIDs.- B. Picovoltmeters.- C. The RSQUID Noise Thermometer.- D. Heat Current Measurement.- 11: “Hot Superconductors”: The Physics and Applications of Nonequilibrium Superconductivity.- I. Introduction.- II. Relaxation Processes and the Kinetic Equations.- III. Magnitudes and the Rothwarf-Taylor Equations.- IV. Solutions of the Boltzmann Equations.- 12: Computer Applications of Josephson Junctions.- I. Historical Notes.- II. The Josephson Junction as a Switching Device.- III. Device Fabrication.- IV. Circuits.- A. Logic Circuits.- B. Memory Circuits.- 13: Programs on Small-Scale Superconducting Devices in Canada.- Programs.- 14: Programs on Small-Scale Superconducting Devices in France.- Programs.- 15: Programs on Small-Scale Superconducting Devices in Germany.- Programs.- 16: Programs on Small-Scale Superconducting Devices in Italy.- Programs.- 17: Programs on Small-Scale Superconducting Devices in the Netherlands.- Programs.- 18: Programs on Small-Scale Superconducting Devices in the United Kingdom.- Programs.- 19: Programs on Small-Scale Superconducting Devices in the United States.- I. Summary.- II. Introduction.- III. Biomedical.- IV. Metrology.- V. Geophysical.- VI. Detection and Radiation.- VII. Digital Processing.- VIII. Device Properties.- IX. Trends.- II — Machines.- 20: Large-Scale Applications of Superconductivity.- I. Introduction.- II. Superconducting Materials and Magnets.- A. Introduction.- B. High-Field Superconductors.- 1. Superconducting materials.- C. Stabilized High Field Superconductors.- 1. Cryostatic stabilization.- 2. Adiabatic stabilization.- 3. Dynamic stability.- D. Conductors for dc and ac Magnets.- E. Irradiation Effects in Composite Superconductors.- F. General Design Aspects of Superconducting Magnets.- 1. Intrinsically stable coils.- 2. Fully or cryostatically stabilized coils.- 3. Current leads and coil protection.- G. Superconducting Magnets for LaboratoryApplication.- H. Magnets for High Energy Physics.- I. Superconducting Magnets for Fusion Reactors and MHD Generators.- 1. Fusion reactors.- 2. MHD generators.- J. Superconducting Magnets for Inductive Energy Storage.- K. Superconducting Magnets for Magnetic Separation.- III. Levitated Vehicles with Superconducting Magnets.- A. Introduction.- B. Basic Features of the Electrodynamic Flight.- C. Principle of the Electrodynamic Levitation System.- D. Various Lift and Guidance Systems.- E. Damping.- F. Propulsion Systems.- G. On-Board Cooling Systems.- H. Magnetic Shielding of the Passengers.- I. Electrodynamic Levitation Projects.- 1. FRG — the Erlangen test carrier and track.- 2. The Japanese National Railway magnetic levitation project.- 3. The Canadian Maglev-projeet.- 4. Work on magnetic levitation in Great Britain.- 5. The US program on magnetic levitation.- IV. Electric Machines.- A. Introduction.- B. Limits of Conventional Machines.- C. Superconducting Machines: General Remarks.- D. DC Machines.- 1. Heteropolar machines.- 2. Homopolar machines.- E. Synchronous Machines.- 1. Technical limits of conventional turbogenerators.- 2. Potential advantages of superconducting generators.- 3. Basic construction of superconducting generators.- 4. Cooling system.- 5. Armature winding (stator).- 6. Machine screening.- 7. Electrical operating behavior and characteristic data.- 8. Economic considerations.- 9. Superconducting turbine-generator projects.- V. Superconducting Cables.- A. Introduction.- B. Superconducting Cable Concepts.- 1. Mechanical construction.- 2. Conductor configurations.- 3. Comparison between superconducting direct current and alternating current cables.- C. Cryogenic Envelope.- D. Superconducting Material.- 1. Direct current superconductors.- 2. Alternating current superconductors.- E. Cable Core.- F. Electrical Insulation.- G. Cable Cooling.- H. Cable Terminations.- I. Superconducting Cable Projects.- J. The Economics of Superconducting Cables.- K. Future Development of Superconducting Cables.- I — SQUIDs.- II — Machines.