The long conductor fabrication is one of key technologies to realize the High-Tc superconducting power cable. A 50-m long conductor was fabricated by helically winding the High-Tc superconducting tape onto a former with a winding machine. The conductor consisted of ten layers of Ag-sheathed Bi-2223 tape which had a high critical current density of 10,000 A/cmZ (at 77 K). AC losses and layer-bylayer current distribution were measured, feeding AC current of 100 to 2,000 Arms to the conductor cooled by LN2. The results showed that most of the current flowed in the outer layers where the impedance was low, and that AC losses were remarkably reduced by making the current distribution uniform.
A meso-porous anodic alumina capillary tube (MAAC) having highly oriented radial meso-pore channels with a minimum diameter of 3 nm has been successfully synthesized using a novel pulse sequential anodic oxidation technique at 100 Hz of pulse frequency. A value resulting in a high channel-pore formation rate at 1 V of the pulse sequential voltage was determined to be the optimum pulse frequency for the anodization. Transmission electron microscopy observation and N2 sorption analysis revealed that controlling the minimum pore channel diameter at 3 nm was possible by the voltage of 1 V. The gas permeance according to Knudsen’s diffusion mechanism was demonstrated at 500 °C, by evaluating gas permeation properties through the meso-porous anodic alumina capillary tube with radial meso-pore channels with minimum diameter of 3 nm, achieving hydrogen permeance of 1.8 × 10−6 mol/m2 s Pa.
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