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This article proposes the deconvolution method to evaluate the lightning channel-base current from the lightning magnetic field. We have verified the method using the magnetic field with/;without noises. The deconvolution results are both in good agreement with the simulated current. Also, we have discussed the deconvolution results when the condition number of the deconvolution matrix, $U_{{0}}$ , is different, and found that the deconvolution results will oscillate if the condition number of $U_{{0}}$ is very large. Note that the deconvolution method presented in this paper also works when using other engineering current models, such as transmission line (TL) model, and the modified TL model with exponential current decaying with height model, and so on. The deconvolution method is an efficient method to evaluate the lightning channel-base current from the electromagnetic field. This approach is also useful in research related to lightning characteristics and lightning protection. [ABSTRACT FROM PUBLISHER]

The overhead catenary system of high-speed railway, usually supported by viaducts, attracts more direct strikes than the conventional railway. However, there are ten thousands of slender steel rods in the reinforced concrete structure of viaducts. Therefore, it takes a lot of time to calculate the model of a long series of viaducts by the conventional electromagnetic field modeling method. An electromagnetic transient model for high-speed railway viaducts struck by lightning based on the decoupling method is proposed in this paper, in which the railway viaducts are divided into the box girder unit and viaduct pier unit. The viaducts model based on decoupling method (VMDM) is established by a series of box units supported by viaduct pier units at equal intervals. The equivalent circuit model of each unit was obtained by employing the vector fitting method based on the frequency-domain response. Experimental results of a newly built railway viaduct pier under lightning impulse current were presented to validate the equivalent circuit model of viaduct pier unit, which show high consistency with simulation results. In particular, the typical VMDM model of Beijing-Tianjin intercity railway viaducts was established with the proposed method. The result obtained from the VMDM model are compared with the simplified model. [ABSTRACT FROM PUBLISHER]