COHERENCE PROPERTIES OF SWISSFEL

The proposed SwissFEL project is an X-ray FreeElectron Laser, which operates down to a wavelength of 1 ˚ Angstrom. In comparison to other XFELs (LCLS, SCSS and European XFEL) SwissFEL has the lowest beam energy of 5.8 GeV. Therefore a low beam emittance is required for maximum overlap between the electron beam and the fundamental FEL mode and for a sufficient degree of transverse coherence at the saturation point. We present a numerical analysis of the radiation field properties along the undulator, with an emphasis on the degree of coherence at the saturation point and at the undulator exit.