Allaria Enrico, Cinquegrana Paolo, Danailov Miltcho B, Ferrari Eugenio, Pannek Fabian, Penco Giuseppe, Roussel Eleonore, Spezzani Carlo
Elettra-Sincrotrone Trieste SCpA, 34149 Basovizza, Trieste, Italy.
Deutsches Elektronen-Synchrotron, Notkestraße 85, 22607 Hamburg, Germany.
J Synchrotron Radiat. 2025 Jan 1;32(Pt 1):72-81. doi: 10.1107/S1600577524011585.
The operation of modern free-electron lasers (FELs) necessitates precise knowledge of electron beam properties at the undulator to ensure the level of control required by increasingly demanding experiments. In seeded FELs, where only electrons interacting with the seed laser contribute to the process, it is crucial to determine the local values of these properties. We present a novel method, based on accurate modeling of the FEL process in high-gain harmonic generation, to accurately retrieve the electron beam slice energy spread, current and laser-induced energy modulation. Understanding these values is essential for enabling advanced FEL schemes and optimally setting advanced seeding schemes such as echo-enabled harmonic generation. We describe the method and provide an experimental application to the FERMI FEL-1, where a slice energy spread in the range 40-100 keV with a few keV accuracy is measured.
现代自由电子激光器（FEL）的运行需要精确了解波荡器处电子束的特性，以确保日益严格的实验所需的控制水平。在种子注入型自由电子激光器中，只有与种子激光相互作用的电子才对该过程有贡献，因此确定这些特性的局部值至关重要。我们提出了一种基于高增益谐波产生中自由电子激光过程精确建模的新方法，以准确获取电子束切片能量展宽、电流和激光诱导的能量调制。了解这些值对于实现先进的自由电子激光方案以及优化设置诸如回声增强谐波产生等先进种子注入方案至关重要。我们描述了该方法，并给出了在FERMI自由电子激光器FEL-1上的实验应用，在该实验中测量了切片能量展宽在40 - 100 keV范围内，精度达到几keV。
