Accelerator-based MeV ultrafast electron microscope (MUEM) has been proposed as a promising tool to study structural dynamics at the nanometer spatial scale and picosecond temporal scale. Here we report experimental tests of a prototype MUEM where high quality images with nanoscale fine structures were recorded with a pulsed 3 MeV picosecond electron beam. The temporal and spatial resolution of the MUEM operating in single-shot mode is about 4 ps (FWHM) and 100 nm (FWHM), corresponding to a temporal-spatial resolution of 4e-19 s*m, about 2 orders of magnitude higher than that achieved with state-of-the-art single-shot keV UEM. Using this instrument we offer the demonstration of visualizing the nanoscale periodic spatial modulation of an electron beam, which may be converted into longitudinal density modulation through emittance exchange to enable production of high-power coherent radiation at short wavelengths. Our results mark a great step towards single-shot nanometer-resolution MUEMs and compact intense x-ray sources that may have wide applications in many areas of science.

中文翻译：

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使用 MeV 超快电子显微镜对相对论电子束进行纳米级空间调制成像

基于加速器的 MeV 超快电子显微镜 (MUEM) 已被提议作为研究纳米空间尺度和皮秒时间尺度的结构动力学的有前途的工具。在这里，我们报告了原型 MUEM 的实验测试，其中使用脉冲 3 MeV 皮秒电子束记录具有纳米级精细结构的高质量图像。MUEM 工作在单次模式下的时空分辨率约为 4 ps (FWHM) 和 100 nm (FWHM)，对应的时空分辨率为 4e-19 s*m，比 MUEM 高约 2 个数量级。这是通过最先进的单次 keV UEM 实现的。使用该仪器，我们提供了可视化电子束的纳米级周期性空间调制的演示，可以通过发射率交换将其转换为纵向密度调制，从而能够产生短波长的高功率相干辐射。我们的结果标志着朝着单次发射纳米分辨率 MUEM 和紧凑型强 X 射线源迈出了一大步，这些源可能在许多科学领域有广泛的应用。