论文标题
基于空腔的X射线自由电子激光器的X射线腔中未对准的签名
Signatures of misalignment in x-ray cavities of cavity-based x-ray free-electron lasers
论文作者
论文摘要
基于空腔的X射线自由电子激光器（CBXFEL）将允许使用光腔反馈来支持Electron中电子中电子高光彩和稳定性的完全相干X射线的生成。 CBXFEL光腔包括刷新的扁平晶体镜，可确保X射线循环在封闭的轨道上，以及X射线折射透镜，可稳定轨道，并将X射线重新聚焦在Undulator中的电子上。根据空腔设计，光学元素的自由度数十个，永远无法完全对齐。在这里，我们研究了光学组件和波动源源的未对准的签名，目的是了解未对准对X射线束动力学的影响，了解未对准的耐受性并开发腔线对齐程序。 X射线束轨迹（对称和不对称）的BETATRON振荡是空腔未对准的特征特征。在通常情况下，振荡周期是腔体中X射线的非整数往返通行证。这个时期（与振荡的振幅和偏移不同）与未对准的类型无关，并且由腔参数定义。研究是在使用分析和数值波光学以及射线追踪技术的四个晶体矩形腔的示例上进行的。研究了共聚焦和通用稳定腔类型。
Cavity-based x-ray free-electron lasers (CBXFEL) will allow use of optical cavity feedback to support generation of fully coherent x-rays of high brilliance and stability by electrons in undulators. CBXFEL optical cavities comprise Bragg-reflecting flat crystal mirrors, which ensure x-rays circulation on a closed orbit, and x-ray refractive lenses, which stabilize the orbit and refocus the x-rays back on the electrons in the undulator. Depending on the cavity design, there are tens of degrees of freedom of the optical elements, which can never be perfectly aligned. Here, we study signatures of misalignment of the optical components and of the undulator source with the purposes of understanding the effects of misalignment on x-ray beam dynamics, understanding misalignment tolerances, and developing cavity alignment procedures. Betatron oscillations of the x-ray beam trajectory (both symmetric and asymmetric) are one of the characteristic signatures of cavity misalignment. The oscillation period is in the general case a non-integer number of round-trip passes of x-rays in the cavity. This period (unlike the amplitude and offset of the oscillations) is independent of the type of misalignment and is defined by cavity parameters. The studies are performed on an example of a four-crystal rectangular cavity using analytical and numerical wave optics as well as ray-tracing techniques. Both confocal and generic stable cavity types are studied.
