• J. Grünert
  European X-ray Free Electron Laser Project Team, c/o DESY, Hamburg

The European XFEL will provide x-ray radiation with properties that challenge diagnostics. Especially its unique pulse train structure of up to 3000 pulses of 100 fs duration, each at only 200ns spacing between neighboring pulses, asks for new approaches to the characterization of these x-ray photons. Also, the highly intense peak power of 20 GW rules out many of the conventional techniques developed for 3rd generation SR sources. The intensity and position monitors will use the interaction of the photons with dilute gases, other online devices could also use parasitically available scattered light, while intrusive but removable detectors will be dedicated to commissioning and optimization before user runs. This is in particular the K-monochromator which ensures during the photon based undulator alignment that the magnetic gap and the phasing between modules are correctly adjusted. The paper presents an overview of the baseline components of the XFEL facility diagnostics system and the requirements to them which result from the extreme radiation conditions.