High Tc Superconducting Materials for Strong Current Applications： Approach at the First Stage

Strong current and large-scale application is the most important prospect of high Te superconductors （HTS）. Practical HTS samples in various forms have been produced with high critical currents operated at economic cryogenic temperatures. Engineering applications of those HTS materials have been studied with various HTS prototype devices. The applicable HTS materials produced in different forms are verified in this paper with regard to their strong current characterizations, and the HTS applications are summarized along with the HTS prototypes made.     

High Temperature Superconductivity in the Past Twenty Years Part 2——Towards to Practical Applications

After discovering high temperature superconducting materials 20 years ago, the preparation of applicable HTS materials has been pursued along with HTS mechanism and characteristic study. At present, the focus on the applied HTS technology has been moving to the industrial preparations from the laboratory research stage, and the technology has been well verified for practical applications from small to large scales. The fabrication techniques of engineering HTS materials are being industrialized; and various HTS devices are also on the way towards practical applications. This paper provides a comprehensive summary on the applied high temperature superconductivity with regard to various applicable HTS materials, their preparation techniques and charac- terization, and applications in a wide range.     

Summary of the First Generation High Temperature Superconducting Wire: Processing,Characterization and Applications

Silver-clad (Bi,Pb)2Sr2Ca2Cu3O10+x long wires produced by powder-in-tube techniques, which have been recognized as the first generation of the High Temperature Superconducting (HTS) wires, are expected to apply widely especially in strong current applications. In this work, the processing, characterization and application of the silver-clad (Bi,Pb)2Sr2Ca2Cu3O10+x HTS wires are summarized. The HTS wires are fabricated using the combination of powder-in-tube technique, and the resulting wires are fully characterized by the means of chemical analyses, microstructural observation, electrical and magnetic measurements. The relationship among fabrication parameters, chemical and microstructural characteristics, and electrical and magnetic properties are analyzed. Applications of the HTS wires have also been introduced according to their strong current behaviors with various prototype devices made.     

Summary of the First Generation High Temperature Superconducting Wire： Processing, Characterization and Applications

Silver-clad （Bi,Pb）2Sr2Ca2Cu3O10＋x long wires produced by powder-in-tube techniques, which have been recognized as the first generation of the High Temperature Superconducting （HTS） wires, are expected to apply widely especially in strong current applications. In this work, the processing, characterization and application of the silver-clad （Bi,Pb）2Sr2Ca2Cu3Ol0＋x HTS wires are summarized. The HTS wires are fabricated using the combination of powder-in-tube technique, and the resulting wires are fully characterized by the means of chemical analyses, microstructural observation, electrical and magnetic measurements. The relationship among fabrication parameters, chemical and microstructural characteristics, and electrical and magnetic properties are analyzed. Applications of the HTS wires have also been introduced according to their strong current behaviors with various prototype devices made.     

High Tc Superconductor Theoretical Models and Electromagnetic Flux Characteristics

High Tc Superconductors （HTS） have special electromagnetic characteristics and phenomena. Effort has been made in order to theoretically understand the appfied HTS superconductivity and HTS behaviors for practical appfications, various theoretical models related to the HTS electromagnetic properties have been developed. The theoretical models and analytic methods are summarized with regard to understanding the HTS magnetic flux characteristic which is one of the most critical issues related to HTS appfications such as for HTS magnetic levitation application.     

High Tc Superconductor Theoretical Models and Electromagnetic Flux Characteristics

High Tc Superconductors (HTS) have special electromagnetic characteristics and phenomena. Effort has been made in order to theoretically understand the applied HTS superconductivity and HTS behaviors for practical applications, various theoretical models related to the HTS electromagnetic properties have been developed. The theoretical models and analytic methods are summarized with regard to understanding the HTS magnetic flux characteristic which is one of the most critical issues related to HTS applications such as for HTS magnetic levitation application.     

High temperature superconductivity: Magnets and applications of naval interest

The Navy has had a long standing interest in power applications of superconductivity. Recent advances in high temperature superconducting (HTS) materials have caused the Navy science and technology community to assess the potential of HTS magnets for Naval applications. A program has begun to test HTS conductors and magnets in order to determine realistic performance expectations from which to determine proper systems integration. This paper presents some early results of industrially produced HTS magnets and discusses possible Naval applications. Speculative application toward magneto-hydrodynamic (MHD) propulsion is also discussed-specifically with respect to HTS materials.     

Features and Prototypes of HTS High Q Resonant Circuit

High Tc superconductor (HTS) technology has been used to develop a unique high Q resonant circuit. Such circuit or device has some special characteristics such as very high voltage generation. Theoretical study and experimental approaches have proceeded for the concept verification. This paper presents the theory about this high Q resonant circuit. The operation principle of the circuit is described. A practical prototype for HTS high voltage generation is also demonstrated. The experiment result shows that very high voltages can be achieved by the developed method using HTS technology.     

Features and Prototypes of HTS High Q Resonant Circuit

High Te superconductor （HTS） technology has been used to develop a unique high Q resonant circuit. Such circuit or device has some special characteristics such as very high voltage generation. Theoretical study and experimental approaches have proceeded for the concept verification. This paper presents the theory about this high Q resonant circuit. The operation principle of the circuit is described. A practical prototype for HTS high voltage generation is also demonstrated. The experiment result shows that very high voltages can be achieved by the developed method using HTS technology.     

SuperPower's YBCO Coated High-Temperature Superconducting (HTS) Wire and Magnet Applications

Recent developments in second-generation (2G) HTS wire and coil technology are presented highlighting the ability of 2G HTS wire to function under demanding operating conditions associated with many applications including linear motors for transportation. The challenges of use in various coil constructions and applications are discussed. The 2G wire architecture of a structural substrate, buffer stack, HTS layer, and stabilization enables the 2G wire to tolerate high stress levels while providing the high current density required for lightweight, compact magnets. The high winding current density that is available with SuperPower's thin (0.1 mm) 2G HTS wire has been utilized in several coil demonstrations, including one generating central fields in excess of 26.8 T. The ability of the wire to be tailored (stabilization, insulation, ac losses) to fit various operating parameters will also be discussed.      

Shape-formed ceramic superconductors by slip-casting

In order to rigorously test emerging applications using prototypes and pilot designs, high temperature superconductor (HTS) materials must be fabricated into a variety of shapes in an economical manner. We have developed a simple, economical, ceramic slip-casting approach to form complex shaped monolithic HTS articles for which high bulk density has been achieved. The sintered articles exhibit good Meissner signal and consist of phase-pure HTSC phase. A low transport critical current density is observed and is explained on the basis of densification and grain growth.     

Development of HTS Transformers and a 10 kVA HTS Transformer Prototype Design

With the improvement of high temperature superconductor （HTS） practical performance, research and development concerning the applications of HTS transformers have been progressed actively worldwide. This paper provides a comprehensive summary on various HTS transformers, and studies the design of a single-phase 10 kVA （220V/24V） HTS transformer prototype to verify HTS for practical transformer applications.     

Quench and recovery characteristics of HTS tapes under oscillating over-currents with different frequencies

Quench and recovery characteristics of Bi-2223/Ag high-temperature superconductor (HTS) tapes under oscillating over-currents with different frequencies have been observed. The experiment is carried out using an oscillating circuit consisted of capacitance and inductance, which produces oscillating currents with different frequencies. The HTS tapes are immersed in liquid nitrogen bath. The frequencies of the oscillating currents fed to HTS tapes are 180.8, 333.3, 434.8, 751.9, and 2016.1 Hz, respectively. In order to confirm the critical current of the tapes, dc current is fed to the tapes first. The magnitude of the oscillating currents is from a small current to 179 A, which is 2.5 times larger than the dc critical current of the tapes. The experimental result shows that the normal voltage generated by the over-current disappears fast after the end of the oscillating over-current, which shows that HTS tapes have good superconducting-to-normal conducting recovery characteristics under oscillating current with high frequency. The experimental results will encourage the possibility of the important applications of HTS tapes in pulsed power.     

Characteristics Measurements of HTS Tape with Parallel HTS Tapes

Many high temperature superconducting (HTS) tape manufactures make an effort to reduce the transport current loss of HTS tapes. The knowledge of critical current and self-field in an HTS tape is very useful to compute the transport current losses. The spatial distribution and magnitude of self-field are variable due to the neighboring materials. In this paper, the critical currents and the transport current losses of BSCCO and YBCO tapes with paralleled magnetic material (Ni tape) and/or diamagnetic material (BSCCO tape) are experimentally investigated to improve the AC loss properties. The critical currents of HTS tapes with paralleled Ni tape are slightly decreased and the transport current losses are markedly increased. However, the critical currents and transport current losses of HTS tapes with paralleled BSCCO tape have not current carrying are more improved than single HTS tape.     

High Temperature Superconductivity in the Past Twenty Years Part 1——Discovery, Material, and Theory

Twenty years after the discovery of hightemperature superconductors （HTSs）, the HTS materials now have been well developed. Meanwhile the mechanism of superconductivity is still one of the topical interests in physics. The achievements made on HTS materials and theories during the last twenty years are reviewed comprehensively in this paper.     

Magnetization Loss and Shield Effect in Multi-Stacked Tapes With Various Stacking Configurations

AC loss is one of the major topics in large AC power applications using high temperature superconductor such as power transformers, transmission cables and fault current limiters because it is closely related to operation efficiency. Multi-stacked tape conductors should be used to transport the large current in those power applications. A research of various arrangements of HTS tapes for multi-stacked tapes has been performed to increase the capacity of transport current in HTS power applications. In this paper, we studied magnetization loss and shield effect from several different arrangements of BSCCO tapes such as Face-to-Face type, regular matrix type (m$times$2) and irregular matrix type. The results show that the magnetization loss of the Face-to-Face arrangement was lower than those of the other matrix types for the same stacking numbers. We think that the result was due to the shield effect by demagnetization of adjacent HTS tapes which were located as face to face.     

高温超导微波器件应用研究进展和建议

高温超导微波技术已经成熟,在美国、欧洲等国家核心战略系统中（例如美国的全球数据传输系统）占有重要地位,在提高通信、雷达等实际系统性能中发挥了重要作用。中科院物理所的应用研究已从核心技术攻关阶段、联机试验验证阶段,进入到用户设备使用阶段。文中对我国超导研究面临的核心技术问题以及领导、规划、项目组织、研究体制等提出了建议。     

Microwave superconductivity

This paper provides an overview of the microwave applications of high-temperature superconductor (HTS) technology. The main characteristics of HTS materials are outlined, highlighting the differences between superconductors and normal conductors. This paper presents recent progress in the development of HTS filters, multiplexers, cryogenic receivers, delay lines, and antennas. A brief summary of cryocooler technology and cryopackaging requirements is presented. The benefits of using HTS technology in wireless and satellite systems are also discussed. The intent of this paper is to provide perspective to newcomers in the field and to empower the potential end-users with current status and performance capabilities of HTS microwave devices     

Structural Parameter Optimization of Multilayer Conductors in HTS Cable

In this paper, the design optimization of the structural parameters of multilayer conductors in high temperature superconducting （HTS） cable is reviewed. Various optimization methods, such as the particle swarm optimization （PSO）, the genetic algorithm （GA）, and a robust optimization method based on design for six sigma （DFSS）, have been applied to realize uniform current distribution among the multilayer HTS conductors. The continuous and discrete variables, such as the winding angle, radius, and winding direction of each layer, are chosen as the design parameters. Under the constraints of the mechanical properties and critical current, PSO is proven to be a more powerful tool than GA for structural parameter optimization, and DFSS can not only achieve a uniform current distribution, but also improve significantly the reliability and robustness of the HTS cable quality.     

Superconducting Electronics Research at CSIRO Australia-20 Years after Discovery of HTS

CSIRO has had a long-term research effort in superconductivity, in particular, since the discovery of HTS which promised big prospects. Significant progress has been made in research and development of HTS electronic devices and systems for practical applications such as mineral and exploration as well as some niche applications in emerging science and technology areas. This article presents an overview of the CSIRO research activities in HTS superconducting electronics since 1987, outlining the HTS junction and device technology as well as various application systems develop by the group.