For more than five decades, ASC has been an important gathering point for the electronics, large scale, and materials fields within the applied superconductivity community, and we’re proud to continue that tradition this year in Seattle, a vibrant urban city set in what is truly one of the most beautiful parts of North America. We hope you will be able to enjoy much of what the city and the region has to offer, and we are also working hard on a technical program that will represent a wide cross-section of the field and an exhibition that will allow you to connect with the industrial representatives who are critical to enabling us, as scientists and engineers, to do our work.
We are further happy to continue partnering with the IEEE Council on Superconductivity to allow submission of conference manuscripts to a special issue of the IEEE Transactions on Applied Superconductivity (TAS), a peer-reviewed and fully indexed and searchable publication available through IEEE Xplore.
On behalf of many, many volunteers making this conference possible – whether serving as members of the ASC Board of Directors, Program Committee, Editorial staff, or as chairs of conference initiatives, we look forward to seeing you in Seattle!
Chair, ASC 2018
In China, we have a complete research system in applied superconductivity. Because of the particular roles of superconducting technology in telecommunication, sensitive transducer, power and energy, maglev transportation, scientific & medical equipment and environmental protection etc., the research for applied superconductivity has been widely supported by the Chinese government, local governments, industry companies, research institutions and universities. In this presentation, we, on behalf of the Chinese colleagues, will report the recent research activities of applied superconductivity in China. In the last decade, China has achieved significant progress in applied superconductivity. For example in superconducting materials, the Western Superconducting Technologies Co. Ltd, founded in 2004, has become one of the most important companies to supply the NbTi and Nb3Sn materials for ITER project, and SAMRI Advanced Material can produce YBCO tape with length up to 1km, and a 10 m long SrKFeAs superconducting tape made at IEE-CAS has achieved Jc of 180A/mm2 @4.2K and 10 T. In the application for electronics, Zhongyi Superconductor is making HTS microwave filter subsystems for base station. Also, a HTS filter subsystem for satellite receiver front-end, developed by a team in IOP-CAS, has been in operation for over two years in orbit. Superconducting nanowire single-photon detector (SNSPD) developed by SIMIT-CAS have been successfully used in 200 km measurement device independent-quantum key distribution (MDI-QKD). Application researches on SQUIDs have been strengthened over the past years with a focus on magnetocardiography, geophysical exploration and ULF-MRI. In power and energy, IEE-CAS has built a demonstration system of a 10kV superconducting power substation, and a 360 m/10kA high Tc DC power cable was experimentally operated for an electrolyze workshop. The Innopower demonstrated a 220kV HTS fault current limiter in the transmission system. In superconducting magnet technology, a 7.0 T magnet for animal MRI has been developed by Tsinghua University and Hangzhou Biopharma Innovation Park Ltd., a superconducting magnet with high Tc insert coil made by IEE-CAS reach the field up to 20 T. Besides, a superconducting TOKAMAK experimental system (EAST) has been built by the Institute of Plasma Physics (IPP) of CAS.
Josephson's discovery in 1962 of the quantum behavior of superconducting junctions enabled a revolution in precision voltage measurement that replaced electrochemical cells, which are artifact standards whose behavior depends upon environmental conditions, with quantum-based standards, whose values are intrinsically accurate and can be reproduced anywhere. Many technological advances in junction fabrication, superconducting integrated circuit technology, bias techniques, and instrumentation were required to achieve the present generation of practical ac and dc voltage standard systems. Quantum-based 10 V programmable Josephson voltage standards and 2 V rms Josephson arbitrary waveform synthesizers are now used in a wide range of metrology applications, calibration laboratories and precision measurement experiments. For metrology, these systems are used for measuring dc and ac voltage, ac power, and impedance. They are also key instruments in precision measurement experiments of mass and temperature to determine more accurate values of the Planck and Boltzmann constants. I will review major technological advances with a focus on the superconducting devices and circuits and describe the current state-of-the-art research and development in superconductive analog and digital circuits that may lead to improved precision measurement of voltage and low-distortion signals for rf communications.
The nearly 80-year-old correlated electron problem remains largely unsolved; with one stunning success being BCS electron-phonon mediated "conventional" superconductivity. There are dozens of families of superconductors that are "unconventional" including the high-Tc cuprate, iron-based, and heavy fermion superconductors. Although these materials are disparate in many properties, some of their fundamental properties are strikingly similar, including their ubiquitous phase diagram in which the superconductivity emerges near a magnetic phase transition and some very strange electronic phases that arise in the non-superconducting states. A recent research direction is towards the fundamental understanding of these phases in the hopes to predictively design higher-Tc, Jc, and practical new superconductors.
The discovery of high-temperature superconductivity by Bednorz and Muller in 1986 inaugurated a new era for research, from both fundamental physics and application perspectives. With Tc routinely around 100 K (the record is 160 K) and Bc2 reaching into tens or even hundreds of Tesla, the technological significance of HTS appeared clear from the very beginning. However, scientists had to face many difficulties to develop these materials in a useful conductor form, and yet only three Bi2Sr2CaCu2O8-x, Bi2Sr2Ca2Cu3O10-x and REBa2Cu3O7-x (RE = rare earth) are available commercially. The grand challenges revolve around the complexity of making high Jc in polycrystalline materials, because of the intrinsic electronic anisotropy and of the great current blocking effects of randomly oriented grain boundaries. This review describes many aspects of the development and property evolution in HTS conductors together with the progress in practical applications.