Electromagnetic Particle-in-Cell Simulation Method And Its Applications

Particle-in-cell (PIC) simulation is an important numerical simulation method for the interaction between charged particles and electromagnetic fields. It is also called the "first principle" method. Over the last recent decades, PIC simulation method and its applications have been significantly affected by the fast development of computer science. It has been widely applied in so many research areas and its applications are keeping growing in recent years.The models for PIC simulation method come in three types:electrostatic, magnetostatic and electromagnetic. The method using electromagnetic model is named electromagnetic PIC simulation method, which is the main topic of this thesis. The research work in this thesis is based on the universal electromagnetic PIC simulation software project supported by the National High Technology Research and Development Program of China.In this thesis, the fundamental theories and numerical analysis have been completely and deeply investigated. Then, some key technique and novel applications are explored and investigated.The main research work is as follows:1. The numerical analysis of electromagnetic PIC simulation method has been investigated in detail. The algorithms can be divided into three parts:electromagnetic field algorithms, charged particle algorithms and field-particle interaction algorithms. Each of them has been discussed respectively. In the first part, time-biased finite-difference time-domain (FDTD) algorithm has been studied and developed, which has been proven to be an effective method to filtrate highfrequency numerical noises. Frequency-domain electromagnetic and static field algorithms have also been studied. In the second part, algorithms for advancing particles in nonrelativistic and relativistic cases have been analyzed, as well as the initial condition and numerical stability for particles. In the third part, algorithms for acting fields on particles have been investigated firstly. Then the detailed formulae for calculating charge density and current density have been given.2. Various boundary conditions for electromagnetic PIC simulation problems have been investigated in detail. The boundary conditions can be divided into two parts:field boundary conditions and particle boundary conditions. Each of them has been discussed respectively. In the first part, excitation sources and absorbing boundary condition have been studied and developed, which have been proven to be practical in PIC simulations. General boundary conditions and other field boundary conditions have also been studied. In the second part, particle emission boundary conditions and other particle boundary conditions have been discussed.3. The design and realization of electromagnetic PIC simulation software have been investigated. Electromagnetic PIC software CHIPIC has been developed based on the fundamental theories and numerical analysis described before. The whole software can be divided into four parts:physical kernel, computer aided design (CAD) system, numerical diagnostics system and parallel computing system. Each of them has been discussed respectively. First of all, the design scheme of the physical kernel has been given. Then, the functions of the other parts have been analyzed, and the concrete design methods during the software development have been given.4. Some important applications of electromagnetic PIC simulation method have been investigated. Lots of research works have been focused on the applications in vacuum electronics science. First of all, the application in vacuum microwave devices has been investigated. A magnetically insulated transmission line oscillator (MILO) tube has been simulated and analyzed. The results are very consistent with experimental results and results described in references. Then, the application in vacuum terahertz sources has been investigated. An extended interaction oscillator (EIO) tube has been simulated and analyzed. The results are valuable for the future experimental work. After that, the application in vacuum electron accelerators has been investigated. An industrial electron accelerator has been simulated and analyzed. Some valuable results have been obtained. At last, the application in gas discharge cathodes has been investigated. The physical phenomena obtained from the simulation are very consistent with physical analysis and experimental results.