Finite difference method is used to simulate the physical process numerically during which the electromagnetic signal is generated by the interaction of nuclear-explosion-induced currents with the geomagnetic field. The EMP waveforms above burst point are researched. The earth-based coordinates and the local spherical coordinates are introduced to illustrate propagating properties of the nuclear electromagnetic pulse along the orbit direction of satellites with various explosion height and yield. Taking into account the attenuation and dispersion of the ionospheric plasma, the FFT method is used to extrapolate the strength of the DEMP. With cosmic noise considered, the peak electric field strength with the yield over 1 kt could be detected at a distance of 10⁴km.

It develops a two-dimensional,fully electromagnetic,relativistic FDTD computer code combined with the PIC method.The physical process of the vircator that electrons are emitted from cathode is simulated.The effects of applied voltage and reflected electrons from the vircator to the diode region are studied preliminarily.