基于改进电测法的Bi-2223/Ag高温超导带的交流损耗研究

研究了B i-2223/Ag高温超导带材的交流传输损耗与频率及运行电流的关系。采用锁相放大器激励,内参考方式,首先对纯阻性相位进行定标的改良电测法,对带材的交流传输损耗进行测量。实验在温度77K,频率45-200Hz的范围内进行。实验结果显示:当运行电流幅值小于临界电流时,传输损耗与电流的关系式(P-In)中,指数n介于2-3之间,说明这时的损耗除来源于磁滞损耗外,涡流损耗的作用也不可忽略。鉴于电测法测得的交流损耗与Norris模型的理论计算值差别较大,分析了这种差别产生的原因,并与另一种B i系高温超导带的交流损耗情况进行了对比;此外还对实验误差的大小进行了理论估测。

Hysteresis and eddy losses in Bi -2223 tapes measured with the improved electrical method

The measurement of AC losses in Bi-2223 tapes is important in qualifying the performance of the superconductor and studying mechanism of the AC losses.In this paper,an improved transport current method was applied to measure the AC losses in Bi-2223 HTS tapes in a frequency range of 45~200 Hz.The measurement was running in an internal reference mode with the phase calibrated first.It was found that the measured AC losses didn't agree well with the Norris' prediction for ellipse.The non-hysteresis losses and the sources of the experimental errors were thoroughly considered and evaluated.According to our results,a pronounced eddy loss effect was observed in the stainless steel reinforced Bi-2223 tapes.Based on the above work,we also come up with a new capacitance compensated method for the measurement of the AC losses in HTS coils.This method was tested in primary experiments.