中文摘要：

分析了位于导电平板上方任意张角的聚焦线圈所产生的线性瞬态电磁场。在单个倾斜圆环线圈电磁模型基础上,推导出了聚焦线圈电磁场量的复频域解析表达式。运用这些表达式和拉氏反变换的数值方法计算了瞬态响应,并讨论了瞬态响应与线圈张角以及平板参数的关系。研究发现,随着线圈张角变小,导体内部涡流密度分布更加集中、时域波形更为陡峭,线圈中感应电动势的峰值变大;平板导体的电导率和磁导率对涡流密度与线圈感应电动势波形影响较大,板厚对瞬态响应影响较小。通过与商用软件仿真结果的对比验证了该文模型与方法,其结果可以用于脉冲涡流检测的信号预测与解释以及探头结构的设计。

英文摘要：

This paper analyzes the linear transient electromagnetic field due to the focusing coil with an arbitrary flare angle above a conducting plate.Based on the model for a single tilted circular coil,analytical expressions in the complex frequency domain for field quantities of the focusing coil are derived.Utilizing these expressions and the numeric method for inverse Laplace transform,transient responses are computed,and the relationship between transients and the coil flare angle,and plate parameters is discussed.The research finds out that as the coil flare angle decreases,the distribution of eddy current density within the conductor becomes more concentrated and its temporal waveform becomes steeper,and the spike peak of coil-induced electromotive force （EMF） increases.Moreover,the conductivity and permeability of the plate conductor exert greater effect on the eddy current density and the coil EMF waveforms than the plate thickness does.By comparison with the simulation result from the commercial software,the model and method proposed in the paper are proved to be validated.The results can be used for the signal prediction and explanation in pulsed eddy current （PEC） testing,and for the design of probe configurations.