Study Of Three-dimensional Parallel Particle-in-cell Simulation Of 140GHz Gyrotron Cavity

The magnetrons of radars were emerged from World War II, and later the particle accelerators were widely used for scientific experiments. The vacuum devices have got great development, such as traveling wave amplifiers for communication and oscillations for the wave heating. The research about wave heating in use of gyrotron is always hot because of the ITER plan. The design of gyrotron needs rely on self-consistent linear theory and particle-in-cell simulation method. Starting from the 70 ’s of last century the PIC method established the basic mathematical framework, and with the development of applications the PIC method constantly got improved in order to adapt to different circumstances. Particle simulation solves the physical problems, while using computers for the solution and evolution of the nonlinear equation with the explicit physical models. The self-consistency and convergence of the equations, and the simplification or optimization of equations are difficulties. Especially the numerical calculations may take some unusual situations, like numerical divergent, numerical exception oscillation and numerical noise. So we try to introduce numerical methods such as some digital filters to get correct results.The emergence of particle simulation method of gyrotron which is much closer to the real physical situations is opposed to classical semi-analytical solution and half-simulation methods. There are more general particle simulation softwares such as MAGIC, KARAT, CST, VSIM. We study the basic algorithms for particle simulation, and use the algorithms for plasma particle simulation research in applications for the gyrotron.This paper is about the algorithm for particle simulation of the cavity for gyrotron. Contents include:1. We study the FDTD method in the Yee grid technology and the leapfrog model of particle simulation. We analyze the absorption of electromagnetic absorbing boundary of CPML. We study the algorithms of filter, and compare with the High_Q method and the time-biased algorithm.2. We study particle emission model, including beam models and meeting space-charge limited emission model, while discussing their reasonableness and advantages and disadvantages. We choose to use a beam model used in simulation.3. We study OpenMP parallel technologies, and set up parallel environment. With senting by implicitly based on shared-memory parallel serial program, parts of the codes get parallelized and the program speed up significantly.4. We calculate the particles with longitudinal stability spiral trajectory in a constant magnetic field case, and design a deflection of particle trajectory under static magnetic field. We choose the right swing model. we select the appropriate algorithm and model simulation based on current, voltage, and particle velocity parameters. We observe the beam-wave interaction processes and particle Velocity distribution in phase space. We compare the difference between simulation results and business software, and give the analysis.