Commissioning of Multi-Segmented Undulators at the TESLA X-ray FEL

Abstract

Abstract Commissioning of the TESLA X-ray FEL undulator cells will start at low electron energy and long photon wavelength (∼6nm) corresponding to the bottom end of TTF phase II operation. Electron and photon diagnostic schemes will be used to monitor the beam trajectory through the various undulator segments. Furthermore, photon diagnostics has to control all undulator gaps and prove the phase tuning of adjacent segments. Using higher harmonics of the spontaneous radiation of individual undulator segments, the photon diagnostic station can cover a wide spectral range and will be able to cope with the progression towards lower SASE wavelength (∼1 A). The use of variable gap undulators allows to realize the photon diagnostic section in a single device located in the photon beamline downstream of the last undulator cell. PACS codes: 41.60.Cr; 42.60.Jf; 07.85.Qe;