中文摘要：

本文采用Jc不均匀超导体模型来研究多晶超导体的磁性质，运用非线性磁通蠕动模型，通过数值模拟得到交流磁化率基波及谐波随温度的变化关系．系统分析了交流磁场振幅和频率改变对Jc不均匀超导体交流磁化率基波及谐波的影响．结果表明，交流磁场振幅和频率的变化对交流磁化率的影响存在显著差异，并归因为交流磁场振幅和频率的改变引起的磁弛豫时间的改变不同所致．上述结果为分析Jc不均匀超导体交流磁化率的实验现象提供了相关依据．

英文摘要：

Using Jc-inhomogeneous model to study the magnetic properties of a sintered superconductor, we obtain the temperature dependence on ac susceptibilities by the nonlinear flux creep model. The influences of ac field amplitude and frequency on harmonic susceptibilities have been analyzed systematically. The influences of ac field amplitude and frequency on ac susceptibilities are obviously different, which are caused by different magnetic relaxa- tion routes when the ac field amplitude and frequency are varied. The results can provide useful information to analyze the experimental results of ac susceptibilities in Jc-inhomogeneous superconductors.