Open AccessThe coherent radiation fraction of low‐emittance synchrotrons
Author(s) -
Westfahl Harry,
Lordano Luiz Sérgio A.,
Meyer Bernd C.,
Meneau Florian
Publication year - 2017
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s1600577517003058
Subject(s) - wavefront , physics , optics , undulator , synchrotron radiation , achromatic lens , coherence (philosophical gambling strategy) , x ray optics , storage ring , radiation , beam (structure) , aperture (computer memory) , gaussian , x ray , quantum mechanics , acoustics
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.