Equivalent current method of excitation source in particle-incell simulation
This paper analyzes the equivalent current method in FDTD for excitation source design.The method is based on the method for avoiding the unwanted non-physical scattering fields in computational electromagnetics.It excites electromagnetic fields by introducing equivalent electric or magnetic current into FDTD formulae.The analysis of the excitation source technology in PIC simulation and the formulae of the new method are also provided.According to the theoretical analysis,the new method has a compact form and can be easily introduced into FDTD formulae for numerical realization.According to the numerical validation,the new method needn't set an addisional scattering field region for scattering field calculation specially,and it has more than 20% higher efficiency and obvious lower requirement of computer memory than general excitation source methods based on the total/scattering field system,so it's very suitable for some time-consuming electromagnetic calculations such as PIC simulation.Further more,the practicability of this method is proved by computing relativistic klystron amplifier(RKA) in 2D cylindrical coordinate system as an example.