Scheme for simultaneous generation of three-color ten GW-level X-ray pulses from baseline XFEL undulator and multi-user distribution system for XFEL laboratory

摘要

The baseline design of present XFEL projects only considers the production ofa single photon beam at fixed wavelength from each baseline undulator. Atvariance, the scheme described in this paper considers the simultaneousproduction of high intensity SASE FEL radiation at three different wavelengths.We present a feasibility study of our scheme, and we make exemplifications withparameters of the baseline SASE2 line of the European XFEL operating insimultaneous mode at 0.05 nm, 0.15 nm and 0.4 nm. Our technique for generatingthe two colors at 0.05 nm and 0.15 nm is based in essence on a "fresh bunch"technique. For the generation of radiation at 0.4 nm we propose to use an"afterburner" technique. Implementation of these techniques does not perturbthe baseline mode of operation of the SASE2 undulator. The present paper alsodescribes an efficient way to obtain a multi-user facility. It is shown that,although the XFEL photon beam from a given undulator is meant for a singleuser, movable multilayer X-ray mirrors can be used to serve many userssimultaneously. The proposed photon beam distribution system would allow toswitch the FEL beam quickly between many experiments in order to make anefficient use of the source. Distribution of photons is achieved on the basisof pulse trains and it is possible to distribute the multicolor photon beamamong many independent beam lines, thereby enabling many users to work inparallel with different wavelengths.