Speaker
摘要
获得超短电子束是超快科学研究的关键，然而二次及更高阶的非线性限制了束团的压缩极限，目前在不进行非线性补偿情况下，电子束仅能压缩到几飞秒的水平。传统射频高次谐波补偿方法可以将束长优化到亚飞秒尺度，但同时会带来无法忽略的能量损耗和射频抖动。本研究通过介质加载波导，利用太赫兹脉冲进行二次非线性补偿。模拟表明，通过高次谐波补偿，10fC电荷、MeV能量范围的电子束的长度可以被压缩到亚飞秒，同时，横向束流尺寸也可以优化至小于 20 微米。此类方法可应用于超快电子衍射（UED）、超快电子显微镜（UEM）和其他超快、时间分辨装置中，以实现更高的时间分辨率。
Abstract
Obtaining ultrashort electron bunches is the key to the studies of ultrafast science, yet second and higher order nonlinearities limits the bunch length to a few femtoseconds after compression. Traditional regulation methods using rf higher order harmonics have already optimized the bunch length to sub-fs scale, yet the energy loss and rf jitter are not negligible. In this paper we demonstrate the second order regulation with THz pulses through a dielectric-loaded waveguide. Simulations suggest that with higher order regulations, the MeV electron bunches with tens of fC charges can be compressed to sub-fs rms and the second order distortion can be compensated. The transverse beam size is also optimized to less than 20um rms. This scheme is feasible for a wide range of electron charges. The relatively short bunch length is expected to find a better time resolution in UED, UEM and other ultrafast, time-resolved studies.
| 关键词 | 束团压缩，超快电子衍射，太赫兹 |
|---|---|
| Keywords | beam compression, ultrafast electron diffraction, terahertz |
