Abstract: This paper introduces an improvement of mini permanent magnet (PM) 2.45 GHz microwave ion source's extraction system at the Institute of Heavy Ion Physics, Peking University. Through simulating and measuring, the magnetic field with or without a 10 cm long PM lens added 9 cm downstream from the PM ring of the ion source was compared. The simulations and experiments indicated that the PM lens can focus the beam effectively. Compared with solenoid lens, this method can simplify the beam transport system, save power and improve the vacuum at ion source region.

Key words: permanent magnet, lens, microwave ion source, extraction system

摘要： 介绍了北京大学重离子物理研究所2.45 GHz袖珍永磁微波离子源引出系统的一项改进，即在距该离子源永磁环9 cm处加一个长为10 cm的永磁透镜。通过计算机模拟和实际测量，对增加此透镜前后比较了磁场分布的变化。模拟计算和实验结果表明，永磁透镜产生的磁场可以有效地聚焦引出的束流，减小引出束流的束斑尺寸。与电磁螺线管透镜相比，该项改进简化了束流传输系统，节省了电功率，并有利于改善离子源区的真空。

关键词: 永磁, 透镜, 微波离子源, 引出系统