The Finite Difference Time Domain (FDTD) Method And Its Application For Plasma Stealth Technology

The topic of this dissertation originates from Major Research Plan of the National Natural Science Foundation of China(No:90405004):Numerical simulation of the radar wave scattering research through aircraft covered with an assembled material composed of absorbed wave coat and plasma layer. The main purpose of this dissertation is to research high–efficiency Finite Difference Time Domain methods suitable for plasma stealth technology and to use the methods to simulate the interaction of electromagnetic wave with plasma.On the basis of the previous research, in this dissertation, the Finite Difference Time Domain (FDTD) method and its application for plasma stealth technology is studied systematically. Not only individual study of FDTD and plasma stealth technology,but also combinational study of them. The dissertation consists of the main four parts, as follows:Firstly, the foundation of the FDTD method is studied. In this part, the Maxwell's equations, Yee algorithm, position of the electric and magnetic field vector components are presented, the separated form of the Maxwell's equations in rectangular coordinate is analyzed, and the numerical stability of the FDTD method is discussed.Secondly, the key part of the FDTD method is studied. In this part, Berenger's perfectly matched layer (PML) absorbing boundary conditions and Gedney's uniaxial PML absorbing boundary conditions are presented, the total-field/scattered field formulations for plane-wave excitation are studied, the radar crossing section (RCS) and near-to-far-field transformation are analyzed.Thirdly, a high–efficiency Finite Difference Time Domain method suitable for plasma stealth technology is studied. In this part, a novel and normalized Z-transforms finite-difference time-domain (ZTFDTD)method is presented. The two-dimensional FDTD formulations for Debye media,Human muscle tissue and unmagnetized plasma are derived.Finally, in this part based on the principles, advantages and disadvantages of plasma, the ZTFDTD method is induced into simulation and calculation of plasma stealth technology and the FDTD software base on ZTFDTD, UPML, RCS is developed. Using the simplified two-dimension models (inhomogeneous unmagnetized plasma cylinder, perfectly conducting cylinder covered with unmagnetized plasma and perfectly conducting thin plate covered with unmagnetized plasma), the stealth effect of unmagnetized plasma is studied in different electron densities of plasma, different electromagnetic wave frequencies and different plasma collision frequencies. Numerical results indicate that plasma stealth is effective in theory and reasonable selection with the plasma parameters can greatly enhance the effectiveness of plasma stealth.