The coherent radiation fraction of low‐emittance synchrotrons. (24th March 2017)

• Record Type: Journal Article
• Authors: Westfahl, Harry; Lordano Luiz, Sérgio A.; Meyer, Bernd C.; Meneau, Florian
• Is Part Of: Journal of synchrotron radiation. Volume 24:Part 3(2017)
• Page Start: 566
• Page End: 575
• Publication Date: 2017-03-24
• Subjects: coherence -- Gaussian–Schell -- diffraction‐limit storage ring; Synchrotron radiation -- Periodicals; Free electron lasers -- Periodicals; 539.73505
• DOI: 10.1107/S1600577517003058
• Languages: English
• ISSNs: 0909-0495

Abstract

Abstract : The coherent fraction of the X‐ray undulator radiation in a fourth‐generation storage ring is analyzed through numerical simulation and analytical models. Abstract : In this work the coherence properties of the synchrotron radiation beam from an X‐ray undulator in a fourth‐generation storage ring are analyzed. A slightly focused X‐ray beam is simulated using a wavefront propagation through a non‐redundant array of slits and the mutual coherence function is directly obtained and compared with the Gaussian–Schell approximation. The numerical wave propagation and the approximate analytical approaches are shown to agree qualitatively, and it is also shown that, when the coherent fraction is selected by a finite aperture before the focusing element, even achromatic focusing systems like total reflection mirrors become slightly chromatic. This effect is also well accounted for in the Gaussian–Schell model. The wavefront propagation simulation through the non‐redundant array was repeated with an imperfect mirror demonstrating that, although the wavefront is distorted, its coherent length is practically unchanged.