The Berliner Elektronenspeicherring-Gesellschaft fuer Synchrotronstrahlung (BESSY) proposes a 2nd generation FEL Soft X-ray user facility (BESSY FEL) in addition to the currently operating 3rd generation light source BESSY II. The BESSY FEL will deliver photon pulses in the wavelength range of 51nm ≤ λ ≤ 1.2nm with pulse durations of a few tens of femtoseconds. To produce these short pulses and to ensure a high shot-to-shot stability a cascaded HGHG FEL scheme is proposed, where the wavelength and pulse duration is determined by an external seeding laser. It is expected to achieve a peak-brilliance of 1031 photons/(s mm2 mrad2 0.1%BW), with GW peak power over the full spectral range. The main components of the BESSY FEL are a photo-cathode injector, a superconducting 2.3 GeV CW-Linac and three independently operating HGHG FEL sections, serving a total of 9 beamlines. A status report is given, including a detailed description of the layout and of the numerical simulations, performed to optimize the machine.
M. Abo-Bakr, M. Abo-Bakr,
"Status of the BESSY soft x-ray FEL project", Proc. SPIE 5917, Fourth Generation X-Ray Sources and Optics III, 591702 (30 August 2005); doi: 10.1117/12.624507; https://doi.org/10.1117/12.624507