Application of Extremely Bright and Coherent Soft and Hard X-Ray Free-Electron Laser Radiation

The first soft x-ray free-electron laser (FEL) is providing extremely bright and coherent radiation since 2005 for a wide range of scientific applications from atomic physics to life sciences. Successful experiments using the FLASH facility at DESY, Hamburg depend critically on radiation parameters such as pulse duration, photon number and coherence properties and, in most cases, request the combination of these parameters in a single experiment. At the same time the transport and preservation of x-ray FEL radiation parameters leads to extreme requirements for x-ray optical elements. The construction of soft and hard x-ray FEL facilities for user experiments with many instruments operating nearly simultaneously led to specialized facility layouts described here for FLASH and for the European XFEL, Hamburg.