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The analysis explains the superconducting properties of the in-situ [MgB.sub.2] tapes, which have SiC and TiC additives and are prepared by the technique of hot pressing. The results reveal that the hot pressing process strengthens the linkage among the grains in the tape.

The study describes the optimization of the [(Nb, Ta).sub.3]Sn wires, which are fabricated using the Sn-Ta sheet by jelly roll processing. It is found that a small amount of Ti and Cu addition in the wires decreases the amount of Ta in the sheet considerably.

Current leads using HTS material are developed for large scale superconducting magnet system as well as a study is conducted to investigate characteristics of Bi-2212 tubular bulk, which is prepared by a diffusion process. 8 kA of the maximum transport current is achieved at 4 K with the bulk size of 38 mm/30 mm in outer/inner diameters and 200 mm in length.

Bi2212 HTS bulk cylinders are prepared by the diffusion process for current lead application. The Bi2212 HTS layer is synthesized through a diffusion reaction between an Sr-Ca-Cu oxide substrate and a Bi-Cu oxide coating with Ag addition.

Structure and high-field performance of (Nb,Ta)(sub 3)Sn conductors fabricated by using ductile Sn-Ta matrix is discussed. Another process for fabricating multifilamentary-type (Nb, Ta)(sub 3)Sn conductors using ductile Sn-Ta/Nb composite is studied.

Describing the mechanism of the thick (Nb,Ta)3Sn layer synthesis, a simplified Ta-Sn powder core process, and a new Jelly Roll (JR) process using Sn-Ta sheet richer in Sn is investigated. The JR wires show attractive high-field performance at 22-23 T, and 5wt%Cu addition tot eh sheet effectively reduces the optimum heat treatment temperature.

Investigating the effect of metal powder addition to the MgB2 core is studied aiming at the improvement of J(sub c) in PIT-processed MgB2 conductors through the introduction of artificial pinning centers or the improvement of grain linkage. TEM observation indicates that the major origin of the J(sub c) enhancement seems to be the improvement of MgB2 grain linkage through the impregnation of fine In into the gaps between grains.

Bi-2212 high temperature superconductor (HTS) bulk conductors have been prepared by the diffusion process, for current lead applications.

Areas of research involving high temperature superconductors (HTS) that are being investigated at Japan's National Institute for Fusion Science (NIFS) are identified and discussed. For example, a superconducting magnetic-levitation coil is being developed.

High temperature superconducting current feeders were developed for a large-scale superconducting experimental fusion system.

Bi-2212 current leads were prepared by a diffusion process and their transport performance was monitored.

A Ta-Sn powder core and Nb-Ta alloy sheath were used to fabricate new (Nb,Ta)3Sn high-field conductors.

YBCO film growth on Y2O3 buffered and nonbuffered SrTiO3 single crystals is described, using fluoride as one of the precursor films.

Recent progress in both LTS and HTS superconductors in Japan is discussed with a focus on Nb-Ti conductors.

The diffusion process was used to prepare Bi-2212 current leads which were synthesized via diffusion reaction betweenSR-Ca-Cu oxide substrates and Bi-Cu oxide coating with the addition of AG.

A study fabricated Nb3Sn conductors with excellent high-field performance using Ta-Sn powder as a core material and a Nb or Nb-Ta alloy sheath using a new process. The Ta-Sn powder was synthesized by melt diffusion reaction between Ta and Sn powders, and encased in a Nb or Nb-Ta alloy sheath. The process used is relatively simple and does not require intermediate annealing for the fabrication. Experimental methods and findings are presented.

The fabrication of a bronze processed Nb3Sn strand, composed of 75990 filaments that are 0.28 micrometer in diameter, into cables of 6 and 36 strands is reported. The 6-strand cable exhibited a substantially improved irreversible bending strain limit of more than 10% that is attributed to fine filament size. The results led to the construction and successful operation of a 50 mm-bore 2T-class magnet that is wound by the 6 strand cable and runs at 52.7Hz at 4.2 degrees Kelvin.

A diffusion reaction between a high melting point Bi-free oxide substrate and a low melting point Bi-based oxide coating layer synthesized the Bi-2212 oxide superconductors. A heat treatment was conducted at 810-870 degrees C in air to produce the Bi-2212 diffusion layer which shows a high density and structure with plate-like grains. Bi-2212 oxide cylinders with large transport Ic and Jc seem to be more effective as current leads and magnetic shields.

A matrix of Cu was used to fabricate an arc-melted Nb-25 wt%Ti alloy into monocore wires. The superconducting properties and structure of the wires were then compared with those of Nb-36 wt%Ti and Nb-46.5 wt%Ti prepared by a similar process. After heat treatment at above 600 degrees C, the formation of a thick Cu-Ti-Nb compound layer was observed at the Cu/Nb-46.5Ti interface. The results showed that the addition of boron enhanced the B(sub c2) and T(sub c) of Nb-25Ti alloy.

A study was conducted on the enhanced Ic-B performance in Tl-based high-temperature oxides fabricated using a diffusion process. The phase transformation from 2223 to 1223 was found to benefit from the F addition. Scanning electron microscopy revealed that the 1223 phase subjected to F addition exhibited an increase in transport Ic at 77 K due to its dense and homogeneous structure.

A diffusion process between a Bi-Cu oxide coating layer and a Sr-Ca-Cu oxide substrate was used to synthesize Bi-2212 oxide superconductors. Results reveal that the silver added to the coating layer improves the diffusion reaction. Results also reveal that the 180-micrometer thick Bi-2212 diffusion layer has high density and a oriented structure with plate-like grains.

Nb6Sn5 intermediate compound powder synthesized by a melt diffusion method was used to develop Nb3Sn superconductors into a tape without intermediate annealing. The tape exhibited a B(sub c2) of 24.7T at 4.2K after the reaction at 900-degrees celsius, which rose further through Ti doping. Temperature and critical current density at high magnetic fields were enhanced through the addition of 0.5-1.0 wt% Ge.

A study was conducted on the effects of several factors on critical current measurements of high temperature superconducting Ag-sheathed monocore Bi2212 and Bi2223 and multicore Bi-2223 tapes prepared through the powder-in-tube approach. The critical current measurement was accomplished at 4.2 K and 77 K in accordance with VAMAS intercomparison guidelines. Results indicate that critical current degradation is caused by tape bubbling.

The results from the second round of the Versailles Project on Advanced Materials and Standards' intercomparison of low-frequency ac loss measurements are reported. The activity involved the round-robin testing of two sets of multifilamentary NbTi strands containing either a copper or a cupronickel matrix. In addition, a supplementary round-robin test was carried out to distinguish errors due to individual sample fabrication.

The results of the Versailles Project on Advanced Materials and Standards' intercomparison of upper critical field (Hc2) measurements of NIST-SRM 1457 NbTi superconducting wire are reported. The activity drew the participation of 12 laboratories from six countries in an effort to standardize measurement methods. It revealed a coefficient of scatter of about 0.60% among the laboratories and lower Hc2 values for the coiled samples.

The diffusion process is used to prepare Tl-base high-critical temperature oxides with fluorine inclusions. X-ray diffraction and electron probe analyses show that the resulting oxides have a critical current of 77 degrees Kelvin. The measured data also indicate that the addition of fluorine in the oxides' coating layer minimizes the degradation of the critical current at shifts the irreversibility line to higher temperature levels.

The utilization of a copper-silicon alloy as the matrix material for alternating current superconducting wires was evaluated. The experiment involved the preparation of the matrix material and the estimation of its mechanical hardness and electrical resistivity, fabrication of the wire by a conventionl stacking process and the measurement of the critical temperature, upper critical field and critical current density of the fabricated wire. Significant functional improvements from its conventional counterparts were derived from the new wire.

The diffusion reaction occurs during the synthesis of high-temperature superconducting composites. The process is influenced by the silver added for raising the diffusion and minimizing the temperature. This is borne out by experiments conducted on Y-123, Bi-2212 and Tl-2223 diffusion samples. The Y-123 and Bi-2212 specimens show an enhanced grain alignment caused by the silver's rise to the surface. This did not occur in the Tl-2223 sample.

The fabrication and characterization of high-temperature superconductors fabricated via a citric salt process is presented. It details the resulting microstructure and superconducting characteristics of YBa2Cu3O(7-x) materials that underwent silver doping and yttrium replacement by zirconium. The results, which were obtained from critical current and temperature measurements, reveal higher critical current densities in the 123 samples at 0 T and 77 K.

The critical current densities and hysteresis losses of bronze-processed Nb3Sn superconducting wires with an Nb-1at%Ta alloy core were measured. The experiment was conducted to determine the impact of adding manganese, nickel, silicon, germanium, boron, zinc and aluminum to the Cu-5at%Sn bronze matrix. The wires design were of the central-copper-stabilizer type and were also tin plated to raise its critical current densities.