Parameter study on phase I of the VUV-FEL at the TESLA test facility

Currently, a SASE-FEL in the VUV, driven by the TESLA test facility accelerator, is under construction at DESY. As a first phase of the project, three of the eight TTF accelerator modules will be installed to deliver an electron beam with a nominal energy of approximately 380 MeV with a peak current of 500 A. With this energy, employing an undulator with the same parameters as for the final design, the resonant wavelength is around 44 nm. For this wavelength, the transverse beam emittance and energy spread conditions can be relaxed as compared to the design wavelength of 6 nm in the final stage. The proposed length of the planar undulator with the integrated FODO lattice is about 15 m. s paper, we present a detailed study on how the performance around 300 MeV depends on the electron beam and undulator parameters. Also, the status of the project is briefly sketched.