Characterization of helical APPLE X undulators with 90 mm period for the European XFEL

Abstract

European XFEL is going to provide full polarization control in the soft X-ray SASE line (SASE3). For this purpose, four helical APPLE X undulators with 90 mm period are installed downstream with respect to the planar undulators of the SASE3 undulator line consisting of 21 planar undulators with 68 mm period. In this contribution, the measurement technique, as well as the results of the measurements and tuning of the APPLE X undulators performed at European XFEL are presented.

Investigating ultrafast structural dynamics using high repetition rate x-ray FEL radiation at European XFEL

“…Additional schemes, where ‚fresh slices' of the bunch are used in the two sub-sequent undulators, are under investigation and can avoid some of the limitations set by the sequential 2-color mode. Tested, but not yet available for users are operation modes to deliver 30 keV x-ray pulses, generated at SASE2 with pulse energies in the few 100 μJ regime, and fully variable polarization in the soft x-ray regime, provided by means of four APPLE-X segments behind the SASE3 FEL [42]. make experiments at European XFEL simpler and less resource demanding.…”