The Unconditionally Stable Complex Frequency Offset Of The Truncated Rotationally Symmetric Geometry Perfectly Matches The Layer

The body of revolution finite-difference time-domain(BOR-FDTD)is usually applied to simulate electromagnetic propagation in rotationally symmetric geometries because of own characteristics.However,it is conditionally stable whose time step can not exceed the Courant-Friedrich-Lewy(CFL)condition.To solve these problems,some unconditionally stable methods are proposed,where Crank-Nicolson FDTD(CN-FDTD)algorithm can keep highly accuracy for large time steps.Besides,the Perfect Matched Layer(PML)is an essential part for FDTD and it has good absorboing performance.The CFS-PML has the best absorbing performance in numerous kinds of PML.This paper researches the free space,PML truncating the free space and the unmagnetized plasma based on unconditionally stable BOR-FDTD algorithms.The main contents of this paper are listed as follows:1.Two algorithms based on CNAD-BOR and SSCN-BOR,named here as CNAD-BOR-FDTD and SSCN-BOR-FDTD,are proposed in free space.Compared them xwith conventional BOR-FDTD about resonance frequency,calculation time and memory occupancy,the results of numerical tests shows that they save more calculation time than conventional BOR-FDTD method on the premise of keeping the accuracy.2.A CFS-PML algorithm based on conventional BOR-FDTD is proposed to truncate the non-magnetized plasma which is also truncated by a SC-PML algorithm based on conventional BOR-FDTD.Compared these two algorithms to confirm the advantage of the CFS-PML.Moreover,a CFS-PML algorithm based on CNAD-BOR-FDTD is proposed to truncate free space and non-magnetized plasma.Besides,a CFS-PML algorithm based on SSCN-BOR-FDTD is proposed to truncate free space.The ADE methods is applied to discretize the model of free space truncated by CFS-PML and the TRC method is applied to discretize the model of non-magnetized plasma truncated by CFS-PML.The absorption performance of the CFS-PML algorithm based on CNAD-BOR-FDTD and SSCN-BOR-FDTD are compared to that of the CFS-PML algorithm based on conventional BOR-FDTD.The results of numerical tests show that two algorithms can save calculation time when absorbing performance of the CFS-PML is acceptale.