Research On The Improved FDFD Algorithm And Half-Space Radiation Coupling Effect

The track circuit system is a key subsystem in the high-speed railway system,which is susceptible to the irradiation coupling interference of strong electromagnetic pulse in space,thus posing a threat to the safety of traffic.In order to accurately analyze the EMP coupling effect of the track circuit,it is necessary to efficiently model the infinite ground and accurately obtain the EMP radiation field distribution in the upper half space of the ground.Therefore,this thesis relies on the actual project of the Key Laboratory of Electromagnetic Environment Effects and Information Processing in Hebei Province to carry out the research,build the simulation model of large area and long distance steel rails,and study the efficient Finite Difference Frequency Domain-Surface Impedance Boundary Conditions(FDFD-SIBC)parallel algorithm to solve the problem that it is difficult to analyze the coupling effect of electromagnetic pulse of long time and long distance steel rails in half space.The main research work and innovations of this thesis include the following three points:(1)Two-dimensional FDFD-SIBC algorithm for half-space ground electromagnetic scattering is studied.Firstly,a two-dimensional half-space electromagnetic scattering model is established by using the surface impedance boundary;then,the phase delay factor of wave propagation is introduced and the twodimensional FDFD-SIBC algorithm for half-space ground electromagnetic scattering is developed;finally,the grid relationship matrix equation of half-space is constructed and solved by the complex conjugate gradient method to obtain the electric field distribution of half-space ground surface.The correctness of the FDFD-SIBC algorithm is verified by numerical simulations of electromagnetic scattering from ideal and consumptive ground surfaces in half space.(2)Research on 3D FDFD-SIBC algorithm extension and parallel computing.Firstly,the three-dimensional extension of the two-dimensional FDFD-SIBC algorithm is realized,and the method of setting the three-dimensional surface impedance boundary is studied;then,based on the Open MP framework,an efficient threedimensional FDFD-SIBC parallel algorithm is studied to reduce the memory consumption to improve the computational efficiency and to realize the fast computation of the radiation field distribution of the three-dimensional half-space ground electromagnetic pulse source;finally,the numerical simulation of the threedimensional half-space Finally,the simulation analysis of the correctness and parallel efficiency of the FDFD-SIBC parallel algorithm is realized by numerical simulation of the 3D half-space ground environment.(3)The coupling effect of nuclear electromagnetic pulse late(E3)irradiation on long-distance steel rails is studied.Based on the theory of skin effect,the equivalent cylindrical model of long-distance rails is studied,and the FDFD-SIBC parallel algorithm is used to rapidly calculate the E3 radiation electric field distribution at each point along the long-distance rails on the ground.On this basis,the E3 irradiation coupling model of long-distance rails on the ground in half space is constructed,and the BLT equation is combined to realize the fast calculation of the E3 irradiation coupling response of rails and analyze the coupling effect law of electromagnetic pulse under different rail lengths.