Analysis of Beam Quality Optimization of Bucket Ion Source

The bucket ion source is widely used as the high energy beam source on the high power neutral beam injector system. A hot cathode bucket ion source is studied. The main parameters which influence the performance of bucket ion source are arc voltage, filament voltage, gas inlet rate and extracted voltage. The proton ratio is the dominate parameter for the ion source. In the experiment, the characteristics of ion source are got by regulate the parameter setting. Based on this, the beam proton ratio, are analyzed and optimized. The proton ratio of extracted beam increased from 28 % to 40 %. It is very useful for the experimental operation and study about the bucket ion source. INTRODUCTION The high power neutral beam injection (NBI) is wildly used for the realization of controlled thermonuclear fusion sciences. The high current ion source is one of the most important parts on NBI, and it is characterized as high plasma density, large dimensions and high proton ratio. In order to promote the performance of ion source, the researchers did many study and experiments, one of them is the proton ratio. The proton ratio is define the percentage of the number of atom ions in the over all species ions number. Consider the hydrogen as the experimental gas, it may generate ions of H1+, H2+, H3+, and the proton ratio[1] can be defined as