We report observations of coherent optical transition radiation interferometry (COTRI) patterns generated by microbunched $\sim 200\text{−}\mathrm{MeV}$ electrons as they emerge from a laser-driven plasma accelerator. The divergence of the microbunched portion of electrons, deduced by comparison to a COTRI model, is $\sim 9\times$ smaller than the $\sim 3\mathrm{mrad}$ ensemble beam divergence, while the radius of the microbunched beam, obtained from COTR images on the same shot, is $<3\mu \mathrm{m}$. The combined results show that the microbunched distribution has estimated transverse normalized emittance $\sim 0.4\mathrm{mm}\mathrm{mrad}$.

中文翻译：

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激光驱动等离子加速器中电子微束的相干光学特征。

我们报告通过微束产生的相干光学跃迁辐射干涉术（COTRI）模式的观察结果 $〜200\text{-}\mathrm{病毒}$电子从激光驱动的等离子体加速器中出来。通过与COTRI模型进行比较得出的电子微束部分的发散度为$〜9\times$ 小于 $〜3\mathrm{姆拉德}$ 整体光束发散，而从同一次拍摄的COTR图像获得的微束光束的半径为 $<3\mu \mathrm{米}$。组合结果表明，微束分布具有估计的横向归一化发射率$〜0.4\mathrm{毫米}\mathrm{姆拉德}$。