X波段光阴极注入器中用于产生高亮度束流的非线性光发射

中文摘要 AI 辅助

低成本紧凑型X射线光源的持续发展对增加原子尺度实验的数量至关重要。小型光源可工作在 blow-out 模式，该模式下高电荷、短束长的电子束会自压缩为均匀椭球形，此模式要求光阴极注入器的激光脉冲持续时间约为10² fs。在此情况下，采用紫外激光的线性光发射存在显著技术挑战，因为许多光学基底在该波长下会退化。本文提出一种替代设计，利用非线性光发射产生高电荷、短束长的电子束。该光阴极注入器设计产生的电子束束电荷最高达200 pC，RMS束长为140 fs，归一化横向发射度为1至1.4 mm·mrad，能量 spread 为10⁻⁴，由此得到的束流亮度为9.74×10¹⁸ A/m²，足以满足本束线的需求。当前正在开展的工作旨在通过使用空间光调制器对激光进行整形，进一步提高电子束亮度。

英文摘要

The ongoing development of low-cost and compact x-ray light sources is vital for increasing the number of experiments that can be performed at the atomic scale. Smaller sources can be operated in blow-out mode, in which a high-charge, short-bunch length electron beam self compresses into a uniformly ellipsoidal shape. This mode necessitates a photoinjector whose laser has a pulse duration on the order of $10^2$ fs. In this case, linear photoemission with an ultraviolet laser presents significant technical challenges, as many optical substrates degrade at these wavelengths. In this paper, we present an alternative design that uses nonlinear photoemission to produce electron beams with high charge and short bunch length. This photoinjector design produces an electron beam with a bunch charge of up to $200$ pC, an RMS bunch length of $140$ fs, a normalized transverse emittance of $1$ to $1.4$ mm$\cdot$mrad, and an energy spread of $10^{-4}$. This results in a beam brightness of $9.74\times10^{18}$ A/m$^2$, which is bright enough for our beamline's purposes. Ongoing efforts are aimed at further increasing the electron beam brightness by using a spatial light modulator to shape the laser

发表机构

• Biodesign Institute, Arizona State University（亚利桑那州立大学生物设计学院）
• Department of Physics, Arizona State University（亚利桑那州立大学物理系）
• Center for Applied Structural Discovery, Arizona State University（亚利桑那州立大学应用结构发现中心）

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