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Evaluation of High Current Negative Ion Source and Construction of Data Base for Negative Ion Based NBI Design

基于负离子的NBI设计的大电流负离子源评估及数据库构建

基本信息

批准号：
02044161
负责人：
KURODA Tsutomu
金额：
$ 2.3万
依托单位：
National Institute for Fusion Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

The objectives of this project are Evolution of high current negative ion source and Construction of data base which is needed for design of negative ion based NBI, especically high current negative ion sources. To attain the objectives we researched the present status of negative ion development at many laboratories in E. C and U. S. A under the collaboration with Culham Laboratory, Ecole Polytechnique and Berkeley Laboratory. Bucket type negative ion source was mainly researched for the optimization of source in pure volume production operation and operation with Cs because of its promissing experimental results. As the results of analysis of experimental data for some issues, the followings are obtained as data base for design of high current hydrogen negative ion source. 1. Experimets for optimization of pure volume source support Tandem model concept of negative ion production. Especially, the plasma parameter measurement by probe shows that the electron temperature in the extraction region is required to be less than 1eV. To realize this condition, a magnetic filter is important to separate the extraction region from the driver region. 2. In the operation mode with Cs, negative ions are mainly produced at low work function wall surface covered with Cs but it is still important condition to keep the electron temperature in the extraction region around 1eV. Detailed data for following physical and technical issues are obtained : 1. Position and strength of magnetic filter, 2. Relation between negative ion current density and extraction aperture radius, 3. Electron suppression in the beam extraction, 4. Bias potential to electrode, 5. R. F negative ion source which is expected as a steady operation source. At the present status of knowledge it is concluded that bucket type negative ion source wit h Cs is most promising high current negative ion source for NBI.

本项目的目标是研究强流负离子源的发展和数据库的建立，这是设计基于负离子的NBI，特别是强流负离子源所需要的。为了实现这些目标，我们与库勒姆实验室、理工学院和伯克利实验室合作，研究了欧美许多实验室的负离子发展现状。桶型负离子源因其良好的实验结果，主要用于纯量生产操作和Cs操作中的源优化研究。通过对有关问题的实验数据分析，得出以下结论，为大电流氢负离子源的设计提供依据。1.优化纯体积源的实验支持负离子产生的串联模型概念。特别是用探针法测量的等离子体参数表明，引出区的电子温度要求小于1 eV。为了实现这种情况，磁过滤器对于将提取区域与驱动区域分开是很重要的。2.在有Cs的工作模式下，负离子主要产生在被Cs覆盖的低功函数壁面，但保持萃取区的电子温度在1 eV左右仍然是重要的条件。获得了以下物理和技术问题的详细数据：1.磁滤光片的位置和强度；2.负离子电流密度与引出孔径半径的关系；3.引出过程中的电子抑制；4.电极的偏压；5.有望作为稳定运行源的Rf负离子源。在目前的认识状况下，带Cs的桶型负离子源是最有前途的NBI大电流负离子源。