Extreme ultraviolet (XUV) radiation is a tool of choice for studying ultrafast processes and atomic physics. Most experiments employing sources of XUV radiation, such as high harmonic generation (HHG) or x-ray lasers, benefit from knowing the number of photons delivered to target in every single shot, because of the possible shot-to-shot pulse fluctuation of the sources. Nonetheless, many setups lack noninvasive XUV pulse energy diagnostics, hindering the simultaneous measurement of pulse energy and utilization of the XUV beam for applications. We present an online XUV pulse energy monitoring method based on the detection of photoelectric charge from thin metallic foil filters transmitting the XUV beam, which can be easily implemented at every pulsed XUV source that includes a high-pass filter system in the form of metallic filters. Consequently, implementation of our method is as straightforward as connecting the filter to an oscilloscope. In the paper, we describe all the physics aspects of such measurement and show the dependence of measured photoelectric charge on the incident pulse energy. To prove the versatility of our approach, we performed this measurement on two different high-flux HHG beamlines, taking consecutive shots at 1 kHz.

中文翻译：

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来自金属过滤器的光电电荷：在线 XUV 脉冲能量诊断


极端紫外线 （XUV） 辐射是研究超快过程和原子物理学的首选工具。由于光源可能存在逐发脉冲波动，因此大多数使用 XUV 辐射源的实验，例如高谐波产生 （HHG） 或 X 射线激光器，都受益于了解每次发射中传送到目标的光子数量。尽管如此，许多设置缺乏无创 XUV 脉冲能量诊断，阻碍了脉冲能量的同步测量和 XUV 光束在应用中的利用。我们提出了一种在线 XUV 脉冲能量监测方法，该方法基于检测传输 XUV 光束的薄金属箔滤光片的光电电荷，该方法可以在每个脉冲 XUV 源上轻松实现，其中包括金属滤光片形式的高通滤光片系统。因此，我们的方法的实现就像将滤波器连接到示波器一样简单。在本文中，我们描述了这种测量的所有物理方面，并展示了测得的光电电荷对入射脉冲能量的依赖性。为了证明我们方法的多功能性，我们在两条不同的高通量 HHG 光束线上进行了这项测量，以 1 kHz 的频率连续拍摄。