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

1.交流纵向磁场中不同细丝排列的Bi2223超导带材的交流总损耗研究了不同细丝排列的Bi2223超导带材在与带长平行的交流纵向磁场中的交流总损耗特性。用标准的管中粉(PIT)工艺制备的带材的总损耗与椭圆形超导体输运损耗的理论预测值(Q&lt；t-椭圆&gt；)和无输运电流的磁化损耗(Q&lt；M0&gt；)之和基本一致。另一方面，对于采用两次轴向轧制的矩形变形工艺制备的分段长丝排列的磁带，其总损失值低于B_0&lt；7mT时的总损失值(Q_t；t-椭圆&gt；q_&lt；m0&gt；)，这是因为在该范围内传输损失占总损失的主要分量。由于磁化损耗对总损耗的贡献随着磁场…的增加而增大振幅B_0越大，总损耗测量值(Q_&lt；t-椭圆&gt；q_&lt；m0&gt；)的偏差在高场范围内变小。这些结果表明，控制带段中的灯丝排列几乎不影响在B_0&>10mT的交流纵场中总损耗的降低。此外，通过控制磁带段的细丝排列，减小细丝厚度和通过层间电阻势垒增加基质的电阻率是降低交流纵向磁场总损耗的重要方法。2.Bi2223超导带材组成的圆柱形导体的交流传输损耗研究了77K下由银套Bi2223超导带组成的双层圆柱形导体的交流传输自场损耗。多股多丝带在直径为10.5 mm的圆柱形成型机上平行排列。损耗的大小受导线中带股排列的影响很大。导体中的损耗产生随着层间距和外层相邻带材之间的间隙长度的增加而增加。通过对导体中每周损耗密度分布的数值计算，认为各导体损耗数值的差异是由磁带束中的自场和损耗产生的磁通分布引起的，并随导体中带束的排列方式而变化。较少

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