回流离子对强流相对论电子束传输的影响

摘要

The paper reports the experimental study of back-streaming ion effect in the target region of Dragon-I linear induction accelerator(LIA). The double-foil technique was used in the experiments. A thin target foil was used to generate back-streaming ions via interaction with electron beam, and a set of beam profile measurement system based on optical transition radiation (OTR) was used to record the time-resolved beam profiles. The study has proved the existence of backstreaming ions in the target region of Dragon-I LIA. The influences of backstreaming ions on high-current relativistic electron beam were observed by u-sing different foils. The beam will partially focus and partially defocus with a metallic foil (Mo) , while dramatic transverse motion will occur with a polymer foil (Kapton).%介绍了采用双膜法测量神龙一号直线感应加速器靶区回流离子效应的实验工作,通过一片厚度数十μm的靶膜产生回流离子,并采用基于光学渡越辐射的电子束剖面测量系统记录时间分辨的束斑,首次证实了神龙一号加速器靶区存在回流离子.通过采用不同材料的靶膜,实验观测到了不同离子发射情况下回流离子对强流相对论电子束传输的影响,结果发现采用金属靶膜时,回流离子导致电子束部分汇聚、部分发散,而采用聚合物薄膜时,回流离子会导致电子束剖面出现剧烈的变化.