The coherent radiation fraction of low-emittance synchrotrons

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.

Source: Journal of Synchrotron Radiation - March 24, 2017 Category: Physics Authors: Westfahl H. Jr Lordano Luiz, S.A. Meyer, B.C. Meneau, F. Tags: coherence Gaussian – Schell diffraction-limit storage ring research papers Source Type: research