金属真空弧离子源引出强流离子束的数值模拟

Numerical simulation of high current ion beams extracted from a MEWA ion source

为了引出更高强度、更高亮度的铀离子束,以满足重离子研究中心(Gesellschaft fur Schwerionenforschung mbH,GSI)重离子同步加速器的需求,本文用三维的计算机程序KOBRA3-INP对金属真空弧离子源(Metal vapor vacuum arc ion source,MEVVA)引出强流铀离子束在引出系统和后加速系统中的动力学特性进行了研究,讨论了离子源发射束流密度对引出束性能的影响。结果表明,束流损失主要发生在引出系统和后加速系统之间的漂移区;在假设漂移区束流被空间电荷中和的情况下,模拟结果和实验结果符合;在发射束流密度为180-230 mA／cm2范围内,经后加速的束流强度变化不大。

To generate uranium ion beam with high current and high brightness to meet the requirement of the heavy ion synchrotron at GSI, KOBRA3-INP code has been used to simulate the behavior of the uranium ion beam in the extraction system and the post-acceleration system for a metal vapor vacuum arc ion source. The influence of the emission current density on the characteristics of the extracted ion beam is discussed. The results show that the losses of the extracted ion beam propagating through the beam line mainly occur in the drift space between the extraction system and the post-acceleration system. Simulation quantitatively supports the experimental results under the assumption that the ion beam has to be space charge compensated along the drift sections. Intensity of the ion beam behind the post-acceleration system is not sensitive to the emission current density in the range from 180 to 230 mA/cm^2.