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2G HTS wires need substantial development to allow ac applications with acceptable losses in ac magnetic fields perpendicular to the tape plane. Filament transposition is necessary to avoid large coupling currents and also to insure a uniform current flow through all the filaments, both of which are essential to minimize ac losses. Conductor twisting solves only the first part of the problem and is not really practical in a tape-shaped wire needing to be wound for instance into compact coils of various shapes. We set out to evaluate a new two-dimensional transposition approach for striated, multifilamentary 2G HIS wire. The new concept uses a so-called transposition zone, located along a linearly striated conductor. In this 7–10 cm long zone all filaments are transposed. The repeat distance of this transposition zone can be as short as 10 m or as long as 100 m, depending on the particular superconducting device and the anticipated ac magnetic fields. In this project a successful transposition approach with acceptable losses was developed. Both the striation method using lateral translations, and sound junction types using different materials, were demonstrated. [ABSTRACT FROM AUTHOR]

Development of the Second Generation (2G) YBCO High Temperature Superconducting wire has progressed rapidly and its performance is approaching, and in some areas exceeding, that of First Generation (1G) HTS wire. American Superconductor's approach to the low-cost manufacturing of 2G wire is based on a wide-strip (4 cm) process using a Metal Organic Deposition (MOD) process for the YBCO layer and the RABiTS (Rolling Assisted Biaxially Textured Substrate) process for the template. In addition, the wide-strip RABiTS/MOD-YBCO process provides the flexibility to engineer practical 2G HTS wires with architectures and properties tailored for specific applications and operating conditions through slitting to custom widths and laminating with custom metallic stabilizers. This paper will review the status of the 2G manufacturing scale up at AMSC and describe the properties and architecture of the 2G wire being developed and tested for various applications including in cables, coils and fault current limiters. Performance of 100 meter class, 4 mm wide wires at 77 K, self-field has reached 100 A (250 A/cm-width) with single-coat YBCO and 140 A (350 A/cm-width) with double-coat YBCO. A 5 cm inner diameter coil fabricated from the latter wire achieved 1.5 T at 64 K, confirming the capability of the wire for coil applications. [ABSTRACT FROM AUTHOR]

Over the past few years, first generation (1G) high temperature superconductor (HTS) wires have been used to demonstrate large-scale prototype devices, including a 5 MW U. S. Navy motor and an 8 MW synchronous condenser. In addition, the fabrication and testing of larger devices (a 36.5 MW motor and a 12 MW synchronous condenser) are currently underway. Although 1G HTS wire will continue to be a workhorse for demonstrating this technology over the next few years, the lower cost potential of second-generation (2G) HTS wire is driving its rapid development and scale-up. In addition to reporting on key material properties of this wire for coil applications, this paper presents thermal cycling data on 2G racetrack coils, showing excellent robustness under conditions of significant thermal strain. A 2G solenoid coil with a 5 cm inner diameter has achieved 1.5 T at 64 K. These results are a major step in confirming the viability of 2G HTS wire in coil applications. [ABSTRACT FROM AUTHOR]

A small pancake coil was wound using 1.2 m long, 10 mm wide YBCO coated superconductor tape with impregnation by epoxy resin. The coil was immersed in liquid nitrogen and tested in several regimes. In the DC regime, we measured the I–V curve, the hysteresis of the magnetic field-current curve at liquid nitrogen temperature and the radial component of the coil field at the coil edges. The critical currents of a short sample at 77 K were also measured and compared with those of the coil. The AC losses measured in the frequency range from 60 Hz to 1000 Hz are compared with those of a similar coil wound with copper tape. The coil heating due to AC losses was monitored. At 60 Hz, the losses of the YBCO coil were nearly two orders of magnitude lower than those in the Cu coil. With increasing frequency, this difference becomes smaller, but the YBCO coil still exhibited lower losses at 1000 Hz. [ABSTRACT FROM AUTHOR]

In the frame of the European Fusion Technology Progranune, the Forschungszentrum Karlsruhe and the Centre de Recherches en Physique des Plasmas, CRPP, Villigen, develop a 70 kA current lead to demonstrate the feasibility of the usage of High Temperature Superconductors (HTS) for the current leads of the ITER TF coils. Design and fabrication of the conventional heat exchanger that covers the temperature range from 65 K to room temperature is done at the Forschungszentrum Karlsruhe. The HTS module connects the current feeder terminal at 4.5 K with the conventional heat exchanger and is cooled only by heat conduction from the cold end. Its design and fabrication has been performed by American Superconductor, AMSC. This module consists of Bi-2223 Ag/Au tapes embedded in stainless steel carriers with copper end caps. It is highly instrumented with voltage taps, temperature sensors and Hall probes. The integration with the heat exchanger and the current feeder terminal is carried out at the Forschungszentrum Karlsruhe. The current lead will be tested in the TOSKA facility in the first months of 2004. The paper describes the design, fabrication and results of pretests carried out at AMSC and Forschungszentrum Karlsruhe. [ABSTRACT FROM AUTHOR]

Investigates the potential of high-temperature superconducting (HTS) magnets for use in naval mine countermeasure systems. Magnet design and parameters; Thermal design; Cryostat/cryocooler integration; Fabrication technology.

Reports on the progress in the development of high efficiency high temperature superconductor 1,000 horsepower motor with the aid of the United States Department of Energy funding under the Superconductivity Partnership Initiative. Objectives of the effort; Program elements to be reviewed; Fabrication and testing of synchronous motors with HTS field windings.