First Results Attained With the Quasi 3-D Ellipsoidal Photo Cathode Laser Pulse System at the High Brightness Photo Injector PITZ

A demand on modern high brightness photo injectors required for a successful operation of linac-based free electron lasers is the possibility to generate beams with minimized beam emittance. A major way to optimize this parameter is the operation of photo cathode laser systems generating shaped laser pulses. Up to now flat-top laser pulses have been used at PITZ to achieve this goal. As a next step in the optimization of photo injectors operated in the space charge dominated regime, the implementation of a photo cathode laser system capable to produce quasi 3-D ellipsoidal laser pulses had been considered as a result of beam dynamics simulations. That show a significant improvement in electron beam emittance compared to conventional cylindrical pulses. The Institute of Applied Physics (IAP RAS, Nizhny Novgorod, Russia) has developed such a photocathode laser system in collaboration with the Joint Institute of Nuclear Research (JINR, Dubna, Russia) and the Photo Injector Test facility at DESY, Zeuthen site (PITZ). The laser pulse shaping is realized using spatial light modulators. The laser system is capable of pulse train generation. Just recently the delivery of the laser system and the implementation of it into the existing laser beam line at PITZ were finished. First electrons generated by the new laser system have been generated shortly after that. Although emittance measurements have not performed yet, the work presented there is a first significant step towards experimental investigation of the advantages of quasi 3-D ellipsoidal photo cathode laser pulses. In this contribution the overall setup, working principles and the actual progress of the development as well as first results of electron beam generation will be reported.