Björn Lautenschlager (DESY)
For pump-probe experiments, where the FEL photon pulses interact together with an external laser, a highly temporal stability is mandatory. The longitudinal beam-based feedback system at the European XFEL stabilizes the arrival time, measured by a bunch arrival time monitor (BAM). To compensate fast arrival time fluctuations of the bunch trains, the energy in front of a bunch compression chicane is modulated by the low level RF (LLRF) system of the superconducting RF (SRF) cavities. Measurements at the EuXFEL shows train-to-train arrival time stabilities down to the sub-10 fs level if the longitudinal intra bunch-train feedback (L-IBFB) is activated at the LLRF system.
Björn Lautenschlager (DESY) Christian Schmidt (DESY) Holger Schlarb (DESY) Jiri Kral (DESY) Julien Branlard (DESY) Marie Kristin Czwalinna (Deutsches Elektronen-Synchrotron) Sebastian Schulz (DESY) Sven Pfeiffer (DESY)