Influence of backstreaming ions from the target on spot size of focused 2 MeV electron beam was considered. The 2D version of the particle-in-cell code KARAT was used to study the formation of the ions stream and dynamics of the electron beam. It was shown that light species emitted from the target can disrupt the beam. The emission of low-ionized states of tantalum cannot disrupt the beam during about 30 ns or longer. A few non-invasive techniques of mitigation of the beam disruption were considered. Final magnetic lens with fast variation of magnetic field of several hundred Ampere-turns per nanosecond is capable to stabilize initial spot size of the compressed beam at the target.

中文翻译：

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回流离子对2 MeV电子束光斑尺寸的影响

考虑了来自靶的回流离子对聚焦的2 MeV电子束光斑尺寸的影响。二维粒子内编码KARAT用于研究离子流的形成和电子束的动力学。结果表明，从目标发出的光会破坏光束。钽的低电离态发射不会在约30 ns或更长时间内中断光束。考虑了一些减轻光束干扰的非侵入性技术。具有每纳秒几百安培匝数的快速磁场变化的最终磁透镜能够稳定目标处压缩光束的初始光斑大小。