Hybrid method simulations of a soft x-ray beamline

A wavefront propagation analysis of a soft X-ray beamline using the HYBRID method is reported. All elements of the beamline: the energy dependence of the insertion device emission, the beamline mirrors and their measured figure errors, the variable-line-spacing grating and its measured figure error, and several exit slit settings, are included in the simulations. The analysis of the propagated undulator radiation through the beamline at two slightly different deflection parameter values demonstrates that, within the beamline angular acceptance and when the monochromator is tuned to the same energy, the flux is higher when the undulator is tuned to slightly higher energy than that of the monochromator. The energy resolution determined from the FWHM of the energy bandwidth transmitted through the exit slit is narrower when the undulator is tuned to higher energy than the monochromator. This is not the case when the resolution is based on the standard deviation of the transmitted energy band. The diffraction effects due to the exit slit size and their consequence on the spot size at the sample position are investigated for a few photon energies.