兆瓦级离子源长脉冲稳定运行物理问题研究

The high power ion source is one of the key parts of neutral beam injector. According to the development of fusion science, the long pulse of high power ion source needs to be studied. For the hot cathode ion source, the plasma density tends to increase and can not operated with long pulse, which is contributes to the cathode self-heating and the energetic electrons backstreaming from the accelerator into the ion source arc chamber. In order to stude the characteristic of long pulse operation of high power ion source, the density feedbach control system is developed in the institute of plasma physics and the ion source can be operated with 100 seconds. The experimental results also shown that, the plasma density has 10% decrease, and it will be unstalbe for high power operation. Based on the physics principles of ion source, the main affecting factors are studied with long pulse operation, respectively. Then, to analyze the working characteristic of density feedback control system, and to optimize to get stable plasma. Further more, to develop the current feedback control system, which is based on the density feedbck control system. And analyze the characteriistic of ion source under the current feedback control, to gets stable long pulse operation. The current feedback control system can be used on the RF ion source in the future. The sutdy of this project can promote the development of high power ion source technology.

强流离子源是中性束注入系统的关键部件之一。随着聚变的发展，强流离子源的长脉冲运行是离子源的必然发展趋势。热阴极离子源由于阴极灯丝的自加热和束引出时高能反向电子流的影响，引起等离子体密度的增加而无法实现长脉冲运行。为了研究强流离子源的长脉冲运行特性，中科院等离子体物理研究所已成功研制了利用密度反馈系统，达到了100秒的长脉冲运行。但在实验中发现等离子体密度有约10%的降低，对高参数的离子源运行仍存在不稳定性。本项目拟从离子源物理原理出发，分别研究离子源运行的主要影响因素在长脉冲工作下是否产生不稳定性，同时针对密度反馈系统，研究其在长脉冲运行下工作特性并进行优化。最后针对兆瓦级强流离子源，基于现有的密度反馈系统，研制电流反馈系统，并分析采用电流反馈下离子源的工作特性，以获得稳定的离子源长脉冲运行，同时本系统可移植于未来的射频离子源等。本项目的研究可促进我国兆瓦级强流离子源技术的发展。

本项目针对热阴极离子源由于阴极灯丝自加热和束引出时高能反向电子流的影响而引起等离子体密度的增加而无法实现长脉冲运行的问题，从离子源物理原理出发，分别研究了离子源稳定运行的主要影响因素，分析了强流离子源稳定运行存在的问题和解决方案。针对热阴极强流离子源在长脉冲工作下的不稳定性研制了密度反馈系统，并研究了其在长脉冲运行下工作特性，同时开展了性能优化工作。此外，为了验证密度反馈系统的可靠性，并考虑事实反馈的可移植性，基于现有的密度反馈系统，研制了电流反馈系统和弧功率反馈系统，并在兆瓦级强流离子源进行了实验测试，分析了采用密度反馈、电流反馈和弧功率三种反馈下离子源的工作特性，并进行了优化，最终获得了强流离子源稳定的100秒长脉冲运行。本项目的研究成果可移植于未来的射频离子源等，研究成果将促进我国兆瓦级强流离子源技术的发展。