Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

We show the design and the parameters of operation of the long-wavelength (U100) FEL at ELBE. First lasing has been shown in August, 2006. Since then, the laser has undergone thorough commissioning and is available for user experiments since fall, 2006. Besides in-house users the IR beam is available to external users in the FELBE (FEL@ELBE) program witch is a part of the integrated activity on synchrotron and free electron laser science in the EU. At the beginning of 2007 lasing in the full designed wavelength range from 20 µm to 200 µm was demonstrated. The laser power typically reaches several Watts in cw operation but drops for very long wavelengths depending on the size of the used out-coupling hole. However, there exists a serious problem with small gaps in the wavelength spectrum. We attribute this behaviour to the transmission characteristics of the overmoded partial waveguide used from the undulator entrance to the first mirror.