Study on Production Mechanism of Multiply-Charged Heavy Ions in ECR Ion Source

本研究的目的是通过东京大学原子核研究所回旋加速器6.4 GHz微波功率的ECR离子源(SF-ECR)的设计、制造、调试和使用，研究ECR离子源中多电荷重离子的产生机理。SF-ECR于1988年开始生产电子束。此外，还研究了6.4 GHz和14.25 GHz微波频率的紧凑型ECR源(HiECR)。[1]研究了6.4 GHz微波频率的SF-ECR离子源(A)SF-ECR具有一个封闭的ECR区(模式I)。结果表明，该模式对Ar以下的气体离子具有很好的性能。(B)SF-ECR研究有两个封闭的ECR区(模式II)。(C)比较了磁场分布不同的两种模式的性能，发现模式II似乎比模式I有更大的潜力在高电荷态产生更大的离子电流。(D)在SF回旋加速器上安装了SF-ECR，并对整个系统进行了性能测试。[2]对6.4 GHz微波频率的HiECR离子源进行了研究，结果表明，这种紧凑型源也具有与SF-ECR相当的良好性能。低电荷态离子产生的电流比SF-ECR大，而高电荷态离子产生的电流较低。[3]14.25 GHz微波频率下HiECR性能研究在试验台上安装了14.25 GHz微波功率源系统。对HiECR性能的研究就是从这个频率开始的。

The aim of this research has been to investigate production mechanism of multiply-charged heavy ions in ECR ion source through designing, manufacturing, tuning, and using an ECR ion source(SF-ECR) with a 6.4-GHz microwave power source for the SF cyclotron of the Institute for Nuclear Study, University of Tokyo. SF-ECR started to produce beams in 1988. In addition, a compact ECR source(HiECR) was studied at 6.4-GHz and 14.25-GHz microwave frequencies.[1] Studies carried out on SF-ECR ion source at 6.4-GHz microwave frequency (a) SF-ECR was studied with one closed ECR zone (mode I). It was found that this mode has excellent performance for gassous ions up to Ar. (b) SF-ECR was studied with two closed ECR zones (mode II). It was found that this mode has similar performance to that of mode I. (c) Comparison between the performances of the two modes which have different magnetic field distributions, however, showed that the mode II seems to have larger potentiality than mode I for producing higher current of ions in higher-charge states. (d) SF-ECR was installed at the SF cyclotron and performance was tested as a whole system. Since it showed satisfactory results, SF-ECR started routine operation.[2] Studies carried out on HiECR ion source at 6.4-GHz microwave frequency This compact source turned out to have also a good performance comparable to SF-ECR. It produced higher current for ions in lower-charge states than SF-ECR, but lower current for ions in higher-charge states.[3] Studies on performance of HiECR at 14.25-GHz microwave frequency A 14.25-GHz microwave power-source system was installed at a test bench. Investigation on performance of HiECR started at this frequency.