DESY, Hamburg, Germany
Stockholm University, Stockholm, Sweden
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
TUL-DMCS, Łódź, Poland
Almost all accelerator-related diagnostic and steering systems require front-end electronic hardware and software for digitizing, synchronization, processing, controlling, and providing access to the control system. Increasingly high demands on resolution, bandwidth, stability, redundancy, low latency, real-time processing and distribution create the need for new technologies in order to fulfill those demands. For this reason, at the European XFEL and FLASH, the new, μTCA industry standard will be deployed. Over the last few years, significant achievements have been made in μTCA developments in collaboration with other research institutes and industry. In this paper, we give an overview of the required components of a typical μTCA system for diagnostics applications. The FLASH bunch arrival-time monitor will be used as an example.
DESY, Hamburg, Germany
The fs-stable timing information in the optical synchronization system at FLASH and the upcoming European XFEL is based on the distribution of laser pulses in optical fibers. The optical length of the fibers is continuously monitored and drifts in signal propagation time are actively compensated in order to provide a phase stable pulse train at the end of the fiber link. At present, optical cross-correlation is used to measure the optical length changes. To overcome some of the disadvantages of the current scheme, a different approach for the detection of the optical fiber link length variation was developed. This new scheme uses 10GHz photodiodes to measure the amplitude modulation of harmonics created by overlapping two pulse trains. The long-term stability of the prototype of this detector over 33h was demonstrated to be below 5fs (peak-to-peak) with a rms jitter of about 0.86fs. The detection principle itself is practically insensitive to environmental influences and needs only about 10% of the optical power, compared to the optical cross-correlator.
DESY, Hamburg, Germany
The free-electron lasers FLASH and European XFEL demand a high timing accuracy between the electron bunches and external laser systems for both exploitation of the short VUV and X-ray pulses in time-resolved pump-probe experiments and seeded operation modes. The required precision can only be achieved with laser-based synchronization schemes. The prototype system installed at FLASH is continuously evolving and subject to improvements. In this paper, we give an overview on the present status, report on the latest developments and extensions, and discuss future challenges. Particularly, the recent move to a new type of master laser oscillator led to a significant enhancement of the robustness and reliability. Consequently, research can focus on the implementation of the electron bunch arrival time feedback, new technologies for timing distribution and integration of Ti:sapphire lasers into the optical synchronization system.