Development of low loss High-T_c superconducting wires based on electromagnetic design and their application to AC power cables

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1.Total AC losses in Bi2223 superconducting tapes with different filament arrangements in AC longitudinal magnetic fieldThe total AC loss properties were investigated on the Ag-sheathed Bi2223 tapes with different filament arrangements in an AC longitudinal magnetic field applied parallel to the tape length. The total loss values in the tape prepared by standard powder-in-tube(PIT) process almost agree with the sum of the theoretical prediction of transport losses in an elliptical superconductor (Q_<t-ellipse>) and measured magnetization loss without transport current (Q_<m0>). On the other hand, for the tape with sectioned filament arrangements prepared by rectangular deformation process with two axial rolling, the total loss values are lower than the values of (Q_<t-ellipse>+Q_<m0>) at B_0<7 mT, because the transport losses are dominant component in total losses in this range. Since the contribution of the magnetization losses to total losses enhances with increasing the magnetic fie … More ld amplitude B_0, the deviation between the measured total losses the values of (Q_<t-ellipse>+Q_<m0>) becomes small in higher field range. These results indicate that the controlling a filament arrangement in a tape section hardly affect the reduction of the total losses in an AC longitudinal field with B_0>10 mT. In addition with controlling the filament arrangements of a tape section, reducing filament thickness and increasing the matrix resistivity by interfilamentary resistive barriers are important to reduce the total loss values in AC longitudinal magnetic field.2.AC transport losses in cylindrical conductors composed of Bi2223 superconducting tapesThe AC transport self-field losses at 77 K were investigated on the double-layer cylindrical conductors composed of Ag-sheathed Bi2223 tapes. The multifilamentary tapes as the strands are arranged in a parallel way on the cylindrical former with a diameter of 10.5 mm. The loss values are strongly influenced by the arrangements of tape strands in the conductors. The loss generation in conductors enhances with increasing of the separation between the layers and gap length between the adjacent tapes in the outer-layer. From the numerical calculations of the loss density distributions per-cycle in the conductors, it is suggested that the difference in loss values for each conductor is attributed to the magnetic flux distributions due to self-field and loss generations in tape strands, varying with the arrangement of tape strands in the conductors. Less