COLLIMATION SYSTEM DESIGN AND PERFORMANCE FOR THE SWISSFEL

Electron beam collimation in SwissFEL is required for protection of the undulators against radiation damage and demagnetization. The design for the SwissFEL collimation for the hard X-ray undulator (Aramis) includes transverse collimation in the final accelerating linac sections, plus an energy collimator in a post-linac chicane. The collimation system must ensure efficient protection of the undulator for various machine modes providing varied final beam energy to the undulator. The performance of the transverse and energy collimation design is studied in simulations including evaluation of the transverse collimation for various beam energies, and the effect of grazing particles on the energy collimator. Collimator wakefields are also considered.