Simulation of High-Altitude Nuclear Electromagnetic Pulse Using a Modified Model of Scattered Gamma

High-altitude electromagnetic pulse (HEMP) generated by the photons from nuclear explosions is a threat to electronic and power systems. During the generation of HEMP, besides the gamma rays released directly by the nuclear devices, the scattered gamma rays can also produce recoil electrons that contribute to the Compton current and further conduction current. Therefore, the gamma-ray model containing both direct and scattered gamma is more accurate to be used in the simulation of HEMP environments. In this article, the modified gamma-ray model based on single-scattering approximation which considers the effects of scattered gamma is presented and the results of the modified model and the traditional prompt-gamma-only model are compared. It is concluded that the scattered gamma rays have little effect on the peak value and rising edge of HEMP. However, the scattered gamma rays influence the electric field at the end of early-time HEMP greatly. This method is also an approach to the scattered gamma component of intermediate-time HEMP.