Post-undulator beam measurements with PolariX TDS in SwissFEL

Abstract

Radiofrequency (RF) transverse deflection structures (TDSs) are fundamental time-resolved diagnostics in x-ray free-electron lasers. Two x-band TDSs with variable polarization of the deflecting force were recently installed after the undulators of Athos, the soft x-ray beamline of SwissFEL. This contribution summarizes the experience gained over the last few months during the commissioning of the RF system and the measurements made during operations, focusing on the setup of the entire complex RF system, the calibration and the time-resolved measurement that, combined with an energy spectrometer, provides longitudinal phase-space measurements of extreme importance for the commissioning of the complex FEL schemes implemented in the Athos beamline.