摘要
全电磁粒子模拟方法可准确模拟强电磁场与电子束之间的非线性相互作用,被广泛应用于真空电子器件的数值模拟研究及参数的优化设计。传统全电磁粒子模拟方法采用电磁场时域有限差分(finite-difference time-domain,FDTD)方法计算器件内电磁场随时间的变化,但FDTD方法采用正六面体单元的结构网格,会带来阶梯误差;电磁场时域有限元(finite-element time-domain,FETD)方法采用非结构网格能准确描述复杂模型,可用于复杂结构的电磁场数值模拟,但需求解大型逆矩阵,无法适用于电大尺寸结构的数值模拟。为准确模拟复杂真空电子器件内电磁场与电子束之间的非线性相互作用,国内外学者在复杂结构共形全电磁粒子模拟技术方面取得了突破性研究进展,实现了基于共形FDTD方法的全电磁粒子模拟技术,开展了基于FETD方法的全电磁粒子模拟技术研究,并研制了数值模拟软件。为促进国内复杂结构共形全电磁粒子模拟技术研究及应用,本文首先对基于共形FDTD方法的全电磁粒子模拟技术研究中的关键技术进行了详细介绍,包括共形结构网格生成技术、电磁场共形FDTD技术、共形电子束发射技术;然后对基于FETD方法的全电磁粒子模拟技术中的关键技术进行了详细介绍,包括所采用的基函数、电磁场方程的求解、计算过程中满足的电荷守恒和高斯守恒定律;同时给出了两种模拟技术对典型真空电子器件的模拟结果。
The fully-electromagnetic particle-in-cell method can accurately simulate the nonlinear interaction between strong electromagnetic field and electron beam,this method is widely adopted in the design and parameter optimization in the vacuum electronic devices(VEDs).Traditional fully electromagnetic particle-in-cell method uses the finite-difference time-domain(FDTD)method to simulate electromagnetic wave in the device.The classical FDTD method uses the structured grid,which will bring the stair-cased error.The finite element method adopts the unstructured grid to accurately describe the complex model and can be used to simulate the electromagnetic field in complex structure,since this method needs to solve large inverse matrix,it is very difficult to employ this method to simulate large-scale structures.In order to accurately simulate the nonlinear interaction between electromagnetic field and electron beam in complex VEDs,researchers have made breakthrough in the field of conformal electromagnetic particle-in-cell(CEMPIC)method.The fully electromagnetic particle-in-cell method based on conformal FDTD method is realized,meantime,the electromagnetic particle-in-cell method based on finite-element time-domain(FETD)method is also proposed,and the numerical simulation codes are developed.To promote the research and application of CEMPIC for complex structures in China,firstly,the key techniques in the study of particle-in-cell method based on FDTD method for complex structures are introduced in this paper in details,including the conformal structured grid generation,conformal FDTD method,conformal electron beam emission.Secondly,the particle-in-cell method based on FETD method is also presented,the key technology including primary function,charge conservation and divergencecleaning algorithms developed in the finite-element particle-in-cell(FEMPIC)is also unveiled.Finally,the typical simulation results for typical VEDs by using the two simulation technologies are also presented.
作者
陈再高
唐泽华
CHEN Zaigao;TANG Zehua(National Key Laboratory of Intense Pulsed Radiation Simulation and Effect,Northwest Institute of Nuclear Technology,Xi’an710024,China)
出处
《电波科学学报》
CSCD
北大核心
2024年第5期808-817,共10页
Chinese Journal of Radio Science
基金
国家重点研发计划(2020YFA0709800)。
