兆瓦级强流离子源弧效率优化研究

High power ion source is the key part of neutral beam injector. The operation efficiency is the key research point for the study of high power ion source. This project is based on the plasma generation and ion extraction, aim at the operation characteristic of mega-watt high current ion source, to study the primary ion generation, plasma confinement, ion extraction and ion source operation mode to gets ideal arc efficiency (the ratio of beam current to arc power). The numerical analysis and experiment research are carried out in this project to study the effects on the arc efficiency and optimize method. The type and distribution of cathode is simulation analyzed to study the effect on the primary electrodes and got the effect on the arc discharge which combines with the change of cathode. The effect of distribution of filaments and multi-pole cusped magnetic field on the confinement of primary electrons and plasma generation are simulation analyzed, and study its effect on the utilization of primary electrons and the production efficiency of plasma. The effect of magnetic field in the extraction area on the ion extraction is analyzed too. The optical characteristic of slit type accelerator is studied with the simulation software, to gets an accelerator with better ion extraction characteristics. The four megawatts high current ion source is optimized based on the theory analysis. The arc efficiency of high current ion source can be improved significantly, which is up to 0.6-0.7 A/kW. The study of this project has important implications for the development and performance optimization of high power ion source. It was also much important for the R&D of the steady-state operation ion source in the future.

强流离子源是中性束注入器的关键设备。离子源的运行效率是大功率离子源研究的重点之一。本项目从等离子体的产生和引出出发，针对兆瓦级离子源的运行特性，在初始电子产生、等离子体约束、引出和离子源运行模式等方面进行研究，以获得理想的弧效率（引出束流强度与弧功率的比值）。本项目通过计算模拟和实验结合的方法，研究弧效率的影响因素和优化方法。利用数值模拟，分析阴极的类型和分布对初始电子发射的影响；分析约束磁场对初始电子约束及等离子体产生的影响；分析引出区磁场对离子引出的影响，模拟分析缝型引出电极对引出光学特性的影响。根据理论研究结果对现有的4MW强流离子源进行优化，在不同灯丝位置、磁场约束位型下，在多种离子源运行模式下进行研究，使强流离子源的弧效率有明显提高,达到0.6-0.7A/kW，有效降低离子源自身功率损耗。本项目的研究对强流离子源的研制及性能优化提供支持，对发展未来稳态运行离子源的发展有重要意义。

本项目按照项目任务书的研究计划按年度开展各研究内容，研究了弧效率的影响因素和优化方法。首先开展了影响强流离子源弧效率的物理分析，并利用数值模拟的方法，分析了阴极的类型和分布对初始电子发射的影响；分析了约束磁场对初始电子约束及等离子体产生的影响；针对离子的引出和离子束的形成，模拟分析了缝型引出电极结构和不同电场对离子引出能力和束流光学特性的影响。根据理论研究结果对现有的4MW强流离子源进行优化，开展了不同运行参数对弧效率的影响分析，并针对模拟分析的结果开展了优化实验研究，包括不同磁场约束位型和不同引出电极对弧效率的影响，最高获得了0.72A/kW的弧效率，并且研究获得了提高强流离子源弧效率的方法。本项目的研究对强流离子源的研制及性能优化提供支持，对发展未来稳态运行离子源的发展有重要意义，从而圆满完成本项目的各项研究内容。