Franssen J G H, Luiten O J
Struct Dyn. 2017 May 26;4(4):044026. doi: 10.1063/1.4984104. eCollection 2017 Jul.
The temporal resolution of sub-relativistic ultrafast electron diffraction (UED) is generally limited by the radio frequency (RF) phase and amplitude jitter of the RF lenses that are used to compress the electron pulses. We theoretically show how to circumvent this limitation by using a combination of several RF compression cavities. We show that if powered by the same RF source and with a proper choice of RF field strengths, RF phases, and distances between the cavities, the combined arrival time jitter due to RF phase jitter of the cavities is cancelled at the compression point. We also show that the effect of RF amplitude jitter on the temporal resolution is negligible when passing through the cavity at a RF phase optimal for (de)compression. This will allow improvement of the temporal resolution in UED experiments to well below 100 fs.
亚相对论超快电子衍射（UED）的时间分辨率通常受用于压缩电子脉冲的射频（RF）透镜的射频相位和幅度抖动限制。我们从理论上展示了如何通过组合使用多个RF压缩腔来规避这一限制。我们表明，如果由同一个RF源供电，并适当选择RF场强、RF相位和腔之间的距离，由于腔的RF相位抖动导致的组合到达时间抖动在压缩点处会被消除。我们还表明，当在（去）压缩的最佳RF相位下通过腔时，RF幅度抖动对时间分辨率的影响可以忽略不计。这将使UED实验中的时间分辨率提高到远低于100飞秒。
