【作者】 金晓林；

【导师】 杨中海；

【作者基本信息】 电子科技大学 ， 等离子体物理， 2007， 博士

【摘要】 电子回旋共振(Electron Cyclotron Resonance,简写为ECR)等离子体源由于具有高密度、高电离度、低运行气压、大体积、均匀、无电极污染、设备简单、参数易于控制、可产生高密度高电荷态离子束等优点而十分引人注目,它被广泛地应用于微电子工业、原子物理、核物理、高能物理与工业应用中。由于ECR等离子体源的广泛应用,对其需求与日剧增,因此对ECR放电及其生成等离子体源特性的研究有着非常重要的意义。本论文围绕ECR放电的理论分析与计算机模拟展开研究工作,主要工作和创新之处在于:(1)对ECR放电及ECR等离子体源的理论、计算机模拟方法进行了综述对ECR放电及ECR等离子体的理论、计算机模拟方法进行了综述、总结与对比。特别指出了模拟ECR放电电离过程的重要意义以及粒子模拟与蒙特卡罗相结合(particle-in-cell plus Monte Carlo Collision,简写为PIC/MCC)方法在模拟研究ECR放电及ECR等离子体特性中的优势。(2)ECR放电电离过程准三维理论分析以通常的ECR放电系统为基础,建立了物理模型,对ECR放电进行了准三维的理论分析,其中包括电磁场的求解、等离子体集体运动、粒子间的碰撞以及带电粒子与边界的相互作用。考虑了电子与中性粒子的弹性、激发、电离碰撞;离子与中性粒子的弹性、电荷交换碰撞;碰撞截面均是能量的函数。总结和发展了适用于ECR放电(可扩展至气体放电)计算机模拟的二次电子发射模型,包括了电子到达边界后被边界吸收、反射、产生真二次电子的三种情形,且具体发生过程依赖于边界材料属性和电子的入射能量与入射角度。(3)ECR放电电离过程准三维模拟在ECR放电电离过程准三维理论分析基础之上进行了数值分析,并编制了ECR放电电离过程的PIC/MCC模拟程序。采用时域有限差分方法并结合总场/散射场体系激励源、吸收边界条件来求解微波场,模拟了微波在ECR放电系统中的传播过程。采用PIC方法中的电磁模型描述了带电粒子与微波自洽的相互作用,MCC方法描述了粒子之间的碰撞过程及带电粒子与边界的相互作用,从而将PIC方法与MCC方法相结合,使得PIC方法处理集体相互作用和MCC方法处理粒子碰撞的优势得以兼顾。(4)ECR放电电离过程的诊断分析通过对ECR放电的PIC/MCC模拟,得到了大量的从放电初期至放电稳态过程中的关于带电粒子运动与微波场的微观信息,展现了电离过程中带电粒子与微波随时间、空间的演化;对如上大量微观信息进行了统计平均,给出了ECR放电及其生成ECR等离子体的部分宏观特性;研究了不同中性气压、外加静磁场形态、微波功率对ECR放电及其生成等离子体特性的影响,可以实现对ECR等离子体源特性的优化。更多还原

【Abstract】 Electron cyclotron resonance (ECR) microwave discharge plasma devices have received a great deal of attention as sources for micro-electronic fabrications, accelerators, atomic physics experiments, and industrial applications et al, due to their high reactive species density, high degree of ionization, low neutral pressure, big volume, uniform, electrodeless operation, and controllable. And the theoretical and computational simulation has been the important method to investigate the characteristics of ECR discharge or ECR plasma.A theoretical and computational model has been presented to study the ionization of the ECR discharge using a quasi-three-dimensional electromagnetic particle-in-cell plus Monte Carlo collision (PIC/MCC) method. The major achievements are listed as the following:(1)Particle, fluid, and hybrid models are focused on the theoretical and computer simulation of the ECR discharge and ECR plasma. In this paper, these three models are reviewed, summarized, and contrasted respectively. It is important to study the ionization of the ECR discharge. And the PIC/MCC method in particle model is preponderant in the simulation of the ECR discharge and ECR plasma.(2)A theoretical model has been proposed to study the ionized characteristics of the argon ECR discharge. The propagation of self-consistent microwave, plasma collective motion, collisions between particles, the interaction between the charged particles and the boundary are taken into account. Elastic, excitational, and ionizing electron-neutral collisions and elastic, charge exchange ion-neutral collisions are included. The cross sections are the functions of particle’s energy. And the secondary electron emission model has been summarized and developed to simulate the behavior of the electron which comes to the boundary in the gas discharge. The secondary emission coefficient is dependent on the impact energy and angle of incidence of the primaries, as well as the material properties of the target. (3)A quasi-three-dimensional electromagnetic PIC/MCC method is used. The simulation code is the original work. The Finite-Difference Time-Domain (FDTD) method plus the source of total/scattering field system and the absorbing boundary condition are used to calculate the propagation of microwave. The interaction between the charged particles and microwave fields are described by particle-in-cell method. The collision processes and the behavior of charged particle which reach the boundary are treated with Monte Carlo method. And the advantages both PIC method to plasma collective and MCC method to collisions are obtained.(4)The detailed microscopic information about the distributions of charged particles and electromagnetic fields from the initial stage to the steady state of ECR discharge are obtained, and the spatio-temporal evolution of the movements of charged particles and the propagation of microwave are shown. The macroscopic features of ECR discharge and ECR plasma are also found by the statistical treatment of the above microscopic information. The effects of neutral pressure, the profiles of external static magnetic and microwave power on the characteristics of the ECR discharge and ECR plasma are investigated to make optimization of the ECR plasma.更多还原