A compact setup with a planar-cathode and grid-anode plus free field drift distance configuration (momentatron) has provided a new way to measure the transverse momentum and, hence, the emittance of the electron beam from a photocathode. This method has been used for analysis of the transverse momentum and emittance of the photoemitted electron beam from the photocathode in a stepwise manner during the fabrication process. The errors caused by the lensing effect from opening holes of the grid anode and misalignments caused by tilting and curving have been systematically analyzed. An analytical method has been developed, and a full three-dimensional electrostatic field particle tracing simulation has been performed to validate this measurement technique. The results show that a momentatron can provide an accurate measurement of transverse momentum and emittance of the photoemitted electrons. The reasonable experimental errors that may be encountered will only have a modest (few %) effect on the emittance measurement.

中文翻译：

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紧凑设置的系统分析，可测量光发射电子束的横向动量和发射率

具有平面阴极和网格阳极再加上自由场漂移距离配置（momentatron）的紧凑装置提供了一种测量横向动量的新方法，因此可以测量光电阴极的电子束发射。该方法已经用于在制造过程中以逐步的方式分析来自光电阴极的光电子束的横向动量和发射率。已经系统地分析了由栅极阳极的开孔引起的透镜效应引起的误差以及由倾斜和弯曲引起的未对准。已经开发出一种分析方法，并且已经进行了完整的三维静电场粒子追踪仿真以验证该测量技术。结果表明，减震器可以提供光电子的横向动量和发射率的准确测量。可能遇到的合理的实验误差只会对发射率测量产生中等（几％）的影响。