A Research On PIC/MCC Simulation Of Multipactor In High Power Microwave Devices

With the growing demand for communication,the frequency band of satellites has been expanding and the power has been significanty increasing,which makes multipactor more likely to ocuur.Multipactor will affect the safety of the spacecraft in orbit.It may even damage the device and thus lead to the failure of spacecraft when multipactor becomes severe.Therefore,it has been an urgent need to research on how to accurately determine the threshold of multipactor,simulate the process of multipactor and effectively suppress the occurence of multipactor.The cycle of experimental research on multipactor is long while the cost is high and the difficulty is great.Only part of the macroscopic characteristics can be obtained because of limitation by various factors.It is still impossible to measure the key parameters such as multipactor threshold accurately at present.With the rapid development of computer,the advantages of numerical simulation are increasingly exposed and it is more frequently applied in research on multipactor,among which PIC/MCC method is the most widely used one.Up to now,scholars have done a lot of research on PIC/MCC numerical simulation of the physical process of multipactor.But there are still many complex physical processes and the mechanism is unknown.At the same time,the huge computational burden of PIC/MCC simulation program greatly limits its wide application in numerical simulation of multipactor.In this paper,based on the above research background and needs,the simulation algorithms and physical characteristics of multipactor are studied based on PIC/MCC method,mainly including the following aspects:1.The background of multipactor and its harm to satellite communication system are introduced;the necessity of multipactor research is explained;the problems existing in experimental research are pointed out;the advantages of numerical simulation in multipactor research are highlighted,and the commonly used numerical methods in the field of multipactor are enumerated;the research history and current progress of multipactor are broadly investigated,and the shortcomings of existing research work are pointed out.2.The fast PIC/MCC simulation algorithms of interaction in multipactor are described;Vaughan model and Furman model,known as two widely used secondary electron emission models,are investigated.Based on the full 3D electromagnetic fast PIC software developed by the team,a secondary electron emission module is added using Furman model with MCC method,and the simulation efficiency is improved by a particle merging algorithm using k-d tree.3.The SEY and EES curves of the secondary electron emission module are tested seperately,and compared with the data from the material library of a commercial software named CST particle studio.A rectangular waveguide is chosen to simulate multipactor using the complete program,and compared with CST particle studio from two aspects including particle phase space distribution and change in particle number.4.By using the PIC/MCC simulation software developed,the process of multipactor threshold detection is simulated in detail through one-step,two-step and coupling method.The influence of multipactor on macroscopic transmission characteristics of microwave devices such as S-parameters and spectrum are studied step by step,and the distribution of particles and the change in local field are analyzed.