2006/09/07 by E.L. Saldin, E. L. Saldin, Saldin, E. L. +6
Engineering · Physics and Astronomy · #Accelerator Physics (physics.acc-ph) #Advanced X-ray Imaging Techniques #Crystallography and Radiation Phenomena #FOS: Physical sciences #Optics (physics.optics) #Particle Accelerators and Free-Electron Lasers #physics.acc-ph #physics.optics
paper · pdf · doi:10.48550/arxiv.physics/0609057
26 pages, 10 figures
arxiv created 2006/09/07 · openalex publication_date 2006/09/07 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a comprehensive analysis of coherence properties of the radiation from X-ray free electron laser (XFEL). We consider practically important case when XFEL is optimized for maximum gain. Such an optimization allows to reduce significantly parameter space. Application of similarity techniques to the results of numerical simulations allows to present all output characteristics of the optimized XFEL as functions of the only parameter, ratio of the emittance to the radiation wavelength, ε = 2πε/λ. Our studies show that optimum performance of the XFEL in terms of transverse coherence is achieved at the value of the parameter ε of about unity. At smaller values of ε the degree of transverse coherence is reduced due to strong influence of poor longitudinal coherence on a transverse one. At large values of the emittance the degree of transverse coherence degrades due to poor mode selection. Comparative analysis of existing XFEL projects, European XFEL, LCLS, and SCSS is presented as well.