A high-brightniess superconducting photo-electorn injector for future FEL's

Most of the proposed electron accelerator projects for future FELs, ERLs, or 4th generation light sources require electron beams with an unprecedented combination of high-brightness, low emittance and high average current. While the concepts of DC- and NC-guns are well proofed, the SRF gun development still possesses a high risk. Challenges are the design of the superconducting cavity, the choice of the right photocathode type, its life time and possible cavity contamination. But in combination with SRF linacs, the SRF guns will be the best solution for high average currents and continuous wave operation.
The contribution will give an overview on the technical concept, the proposed performance, and the current status of the leading superconducting rf gun project developed in Dresden-Rossendorf. At the moment the cryomodule and a diagnostic beamline are installed next to the ELBE superconducting linear accelerator. During the first commissioning and test period the gun is operated in parallel to the existing dc thermionic gun, but at the end of 2008 it will be used to improve the beam quality of the ELBE accelerator significantly.
The first beam, using a copper cathode, was imaged on the screens on 12th November 2007. The UV-laser with an output power of 400mW at 100kHz rep. rate produced a beam current of 40nA and a corresponding bunch charge of 0.5pC. At next the commissioning of the diagnostic beamline, to measure all important beam parameters, will be finished and first high current tests using a Cs2Te-Cathode will be done.