Longitudinal crossover and the dynamics of uniform electron ellipsoids focused by a linear chirp
Longitudinal crossover and the dynamics of uniform electron ellipsoids focused by a linear chirp
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线性调频聚焦的均匀电子椭球的纵向交叉和动力学
DOI：
10.1103/physreve.103.023202
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发表时间：
2021
影响因子：
2.4
通讯作者：
Zerbe, B.
中科院分区：
文献类型：
--
作者：
Xiang, X.;Duxbury, P. M.;Zerbe, B.
高分辨率单次非相对论超快电子显微镜 (UEM) 依靠自适应光学器件使用射频 (RF) 腔压缩高强度电子束。我们全面讨论了当电子束经过射频腔后的纵向焦点时可用于表征束动力学的分析方法，其中空间电荷效应可能很大。在某些情况下，对库仑爆炸文献、加速器物理文献和为 UEM 开发的解析高斯模型中提取的方法进行了比较、利用和扩展。特别地，纵向焦点可能出现在两种不同的状态中，即反弹状态和交叉状态；我们在零发射模型中描述了分隔这些状态的临界点。将使用有效多极子方法的粒子模拟结果与理论模型进行比较，揭示需要扩展分析方法的特征；特别是讨论了发射增长和转移的机制。
High-resolution single-shot nonrelativistic ultrafast electron microscopy (UEM) relies on adaptive optics to compress high-intensity bunches using radio frequency (RF) cavities. We present a comprehensive discussion of the analytic approaches available to characterize bunch dynamics as an electron bunch goes through a longitudinal focal point after an RF cavity where space charge effects can be large. Methods drawn from the Coulomb explosion literature, the accelerator physics literature, and the analytic Gaussian model developed for UEM are compared, utilized, and extended in some cases. In particular the longitudinal focus may occur in two different regimes, a bounce-back regime and a crossover regime; and we characterize the critical point separating these regimes in the zero-emittance model. Results from-particle simulations using efficient multipole methods are compared to the theoretical models revealing features requiring extensions of the analytic approaches; and in particular mechanisms for emittance growth and transfer are discussed.