在中性束离子源引出过程中,详细分析了引出束流的产生,这有利于得到更准确的引出功率和引出电极表面的热功率沉积情况。根据HL-2A装置中性束离子源引出电极的电连接方式和束流引出的物理过程,对离子源束流引出过程进行了分析,给出抑制极电流产生的主要来源。通过分析放电气压扫描实验中的结果发现：随着放电气压的增加,不同弧放电电流情况下抑制极电流均逐渐增加,且抑制极电流与引出电流的比值近似线性增加。针对引出离子束流经过引出电极的过程建立了物理模型。计算了抑制极电流与引出电流的比值与放电气压的依赖关系,计算结果与实验结果一致,验证了引出束流分析结果的合理性。

In the extraction process of neutral beam ion source, the production of extraction current and deceleration current is analyzed and it is helpful for obtaining reliable extraction power and heat deposition power on the grids’ surface. Based on the electric connection way of the extraction grids of neutral beam ion source on HL-2A and the basic physical process during ion beam extraction, beam extraction process is analyzed and the principle sources of deceleration current are given. Through analyzing the results in gas pressure scanning experiment, it is found that with gas pressure increasing, deceleration current increases, and the ratio of deceleration current to extraction current increases approximately linearly. A physical model is set up based on the process of extracted ion beam coming through the extraction grids. The dependence of the ratio of deceleration current to the acceleration current on the discharge gas pressure is calculated, and the result is consistent with the experimental result which shows the rationality of the analysis method.