交流磁场对高温超导体交流损耗的影响  

INFLUENCE OF AC MAGNETIC FIELD ON AC LOSSES OF HIGH-T_c SUPERCONDUCTOR

作　　者：纪圣谋[1] 丁世英[1] 徐健健[1] 

机构地区：[1]南京大学物理系,南京210093

出　　处：《低温物理学报》2007年第3期233-236,共4页Low Temperature Physical Letters

摘　　要：本文报道交流磁场对高温超导体交流损耗Q的影响.基于对数型位垒的巨磁通蠕动模型,我们进行的数值计算证明,交流损耗与交流振幅的关系在定性上是和临界态模型相同的,即与振幅的m次方成正比:Q∝(Bac)m.但是,m不是像Bean模型预言的那样只有m=1和m=3的两个值,而是渐变的,MgB2和Ag/Bi2223样品的实验结果支持我们的结论.This paper reported studies about the influence of ac magnetic field on ac losses of superconductors. Numerical calculation based on flux creep model with logarithmic barrier U showed that the dependence of ac losses Q on the amplitude of ac field Bac, is still governed by Q ∝ Bac^m, predicted by the Bean model. However, in our simulation m varies from 1 to 3 continuously instead of being 1 or 3 in the Bean model, where m = 3 and m = 1 correspond to the current and ac field being un-penetrated and penetrated, respectively. Calculation showed that the power m changes continuously is due to the corresponding current density and field are changing continuously. The experimental results for our MgB2 sample and theAg/Bi2223 tape in reference supported the numerical conclusion.

关 键 词：高温超导体 交流损耗 磁通蠕动 数值计算 

分 类 号：O511.3[一般工业技术—材料科学与工程]