At a soft X‐ray beamline with an undulator source, significant heat generation at the first‐mirror chamber and light emission at the viewport were found, which can be explained by photoelectrons from the mirror. The chamber temperature increases up to approximately 50°C over a period of several hours. A photoelectron shield consisting of thin copper plates not only prevents the heat generation and light emission but also improves the pressure of the vacuum chamber, if a voltage of a few tens of V is applied to the shield. The total electron yield of the shield reached as much as 58 mA under high heat‐load conditions, indicating the emission of numerous photoelectrons from the first mirror. Heat‐balance analyses suggest that approximately 30% or more of the heat load on the first mirror is transferred to the surroundings.

中文翻译：

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软X射线束线的第一面镜的光电子屏蔽

在带有起伏源的软X射线光束线上，发现在第一镜腔产生大量热量并在视口发出光，这可以通过镜中的光电子来解释。在数小时内，腔室温度升高到大约50°C。如果将几十伏的电压施加到屏蔽层上，则由薄铜板组成的光电子屏蔽层不仅可以防止热量的产生和发光，还可以提高真空室的压力。在高热负荷条件下，屏蔽的总电子产量高达58 mA，表明第一面反射镜发射了许多光电子。热平衡分析表明，第一面镜上约有30％或更多的热负荷传递到周围环境。