Second-Order Accurate FDTD Method for Nonuniform Plasma at Multilayer Interfaces

The second-order accurate finite-difference time domain (FDTD) method for nonuniform nonmagnetized plasma at multilayer interfaces is proposed based on the PLJERC scheme and Taylor series. The definition of the accuracy order of difference equations is given and a brief demonstration is presented to illustrate that the FDTD equations at the discontinuous interface based on the reflection coefficient theory is only first-order accurate. Second-order accurate FDTD equations are deduced according to the effective electron density at the interface both for the H-i-E case and the E-i-H case. A reflection coefficient test is done on a PEC slab covered by multilayer nonmagnetized plasma to validate the accuracy of the proposed FDTD method. Calculation results show that the reflection coefficient obtained by the proposed method coincides with that of the analytic methods well and the proposed method has higher accuracy than the conventional FDTD method. The reflection characteristics of the multilayer plasma with four typical electron density distribution profiles and versus incident angle, frequency, and electron collision frequency are analyzed by the proposed method.